FUEL COMPOSITION

Abstract: Unleaded blend compositions, as well as formulated gasolines containing them have a Motor Octane Number (MON) of at least 80 comprising at least 2 % of component (a), which is at least one branched chain alkane of MON value of at least 90 and of boiling point 15-160 DEG C or a substantially aliphatic hydrocarbon refinery stream, of MON value of at least 85, at least 70 % in total of said stream being branched chain alkanes, said stream being obtainable or obtained by distillation from a refinery material as a cut having Initial Boiling Point of at least 15 DEG C and Final Boiling Point of at most 160 DEG C, said Boiling Points being measured according to ASTMD2892, and as component (g) at least 5 % of at least one paraffin, liquid hydrocarbon or mixture thereof e.g. aromatic hydrocarbon compound or olefinic hydrocarbon of bp60-160 DEG C, especially of MON value at least 70 and RON at least 90 or as component (g) at least 20 % of one or more refinery streams. The component (a) gives rise to reduced emissions to the composition or gasoline on combustion.

Description: FUEL COMPOSITION This invention relates to fuel compositions, in particular a gasoline composition for use in motor vehicles, for or for use in aircraft. For many years manufacturers of spark ignition combustion engines have been striving for higher efficiency to make optimum use of hydrocarbon based fuels. But such engines require gasolines of good octane number has been achieved in particular by addition of organo lead additives, and latterly with the advent of unleaded gasolines, by addition of MTBE. But combustion of any gasoline gives rise to emissions in the exhaust gases, e.g- of carbon dioxide, carbon monoxide, nitrogen oxides (NOx) and toxic hydrocarbons and such emissions are undesirable- Unleaded Motor gasolines have been discovered producing low emissions on combustion- In a first aspect the present invention provides use of component (a), which is at least one of (i) a substantially aliphatic hydrocarbon refinery stream of MON value of at least 85, at least 70% in total of said stream being branched chain alkanes, said stream being obtainable or obtained by distillation from a refinery material as a cut having Initial Boiling Point of at least 15°C and a Final Boiling Point of at most 160°C, said Boiling Points being measured according to ASTMD2892, and (ii) at least one branched chain alkane of MON value of at least 90 and boiling point in the range 15-160°C, especially apart from 2,2,3-trimethylbutane and 2,2,3-trimethylpentane, in an unleaded gasoline of MON at least 80 to reduce the emission levels on combustion of said gasoline. v In a second aspect the present invention provides a method of reducing emissions of exhaust gases in the combustion of an unleaded gasoline fuel of MON at least 80 which comprises having present in said gasoline at least 10% of component (a) as defined above. In a third aspect the present invention provides use in a spark ignition combustion engine of an unleaded gasoline fuel of MON at least 80 which comprises at least 10% of component (a) as defined above to reduce emissions of exhaust gases. In a fourth aspect the present invention provides an unleaded composition having a Motor Octane Number (MON) of at least 80 comprising at least 2 or at least 5%, in particular at least 10%, such as 5-70% (by volume of the total composition) of component (a), which is a substantially aliphatic hydrocarbon refinery stream, of MON value of at least 85, at least 70% in total of said stream being branched chain alkanes, said stream being obtainable or obtained by distillation from a refinery material as a cut having Initial Boiling Point of at least 15°C and Final Boiling Point of at most 160°C, said Boiling Points being measured according to ASTMD2892, and as component (g) at least 5% of at least one paraffin, aromatic hydrocarbon compound or olefinic hydrocarbon of bp60-160°C, with not more than 5% of the total composition, e.g. less than 1%, of hydrocarbon of bp more than 160°C, especially compounds with at least 2 hydrocarbyl rings such as naphthenes, and preferably less than 5% e.g. less than 4% of triptane or 2,2,3 trimethyl pentane. All boiling points quoted herein are at atmospheric pressure. In a fifth aspect the present invention also provides an unleaded composition having a Motor Octane Number (MON) of at least 80 comprising at least 5% in particular at least 10%, such as 5-70% (by volume of the total composition) of component (a), which is at least one branched chain alkane of MON value of at least 90 and of boiling point in the range 15-160°C e.g. 15-100°C, said alkane being preferably present in amount of at least 10, 20 or 30% (especially 10-50%) of the total saturated content of said composition, and as component (g) at least 5% of at least one paraffin, aromatic hydrocarbon compound or olefinic hydrocarbon of bp60-160°C, with not more than 5% of the total composition, e.g. less than 3%, of hydrocarbon of bp more than 160°C, especially naphthenes and preferably less than 5% e.g. less than 4% of triptane or 223 trimethyl pentane. In a sixth aspect the present invention provides an unleaded blend composition having a Motor Octane Number (MON) of at least 81 or 85 and Research Octane Number (RON) of at least 91 or 94 which comprises component (a) a total of at least 15% by volume of the blend composition of at least one branched chain hydrocarbon, which is an alkane of 8-12 carbon atoms with 3 methyl or ethyl branches (hereinafter called a compound (A)) there being a minimum of at least 10% by volume (of the blend composition), of at least one individual compound (A) and component (g) at least one liquid hydrocarbon (e.g. paraffin, aromatic hydrocarbon or olefin) or mixture thereof of bp60-160°C having a MON value of at least 70 and RON value of at least 90, the total amount of component (g) being at least 20%, with the preferred proviso that the blend composition contains less than 5% of 223 trimethyl pentane, and especially less than 1 or 0.5%, and especially less than 0.5%, in total of 223 trimethyl butane and 223 trimethyl pentane. In a seventh aspect of the present invention provides an unleaded blend composition of MON value of at least 81 or 85 and RON value of at least 91 or 94 which comprises component (a) as defined in the previous paragraph and as component (g) at least 20% in total of one or more refinery streams (e.g. such as those described below in relation to any of (b) to (e) below)), such that the blend composition contains in total at least 70% of saturated hydrocarbons. In the first aspect the substantially aliphatic refinery stream contains at least 90% aliphatic hydrocarbons (e.g. at least 95%) and at most 10% in total (e.g. at most 5%) of nonaliphatic hydrocarbons, such as cycloaliphatics e.g. cyclopentane, cyclohexane, alkenes such as linear or branched, ones e.g. butenes, pentenes, hexenes, heptenes and octenes, and possibly, but preferably not, aromatic hydrocarbons such as benzene and toluene. The MON value of said stream is at least 85, e.g. at least 87, or 90 or 92, in particular less than 100, e.g. 85-96 or 87-95, such as 87-90 or 90-95. The RON value of said stream may be 0.5-3.5 especially 1.0-3.5 or 0.5-2.5 units above its MON value, such as RON values of 88-98, or 89.5-96. In said stream at least 70% in total are branched chain alkanes, there being 1 or at least 2 e.g. 2-10 of such alkanes; especially present are 2-4 such alkanes, each in amount of at least 10% or especially 20% e.g. 20-60% in said stream. Thus the stream may contain at least 70% isopentane, or at least 10% (e.g. 10- 40%) of each of 2,3dimethyl butane (e.g. 20-40%), isopentane, 2,3 dimethyl pentane (e.g. 20-40%) and 2,4 dimethyl pentane (e.g. 20-40%), or at least 10% (e.g. 10-40%) of each of 2,3 dimethyl butane, 23 and 24 dimethyl pentanes (e.g. 20-40%), and isooctane (e.g. 20-40%). Streams containing less than 30% isopentane e.g. 5-25% isopentane may be preferred, especially if the composition contains at least 5% of triptane or 2,2,3 trimethyl pentane. The total of branched chain alkanes in said stream is at least 70% such as 70-85%, the remainder if any being linear alkanes such as n-butane, n-pentane and/or non aliphatics as described above. The aliphatic refinery stream is usually derived from a refinery material which is an alkane conversion product, made by reacting one or more alkanes or alkenes, e.g. of 3-5 carbon atoms, especially branched compounds, such as reaction of an alkane and an alkene e.g. isobutane and isobutene. Examples of such a conversion product are alkylates, which may be made by such a reaction. Alkylates are known refinery products, see e.g. Our Industry Petroleum, by British Petroleum Co., London, 4th Ed. Publ. 1970 page 187. Acid catalysts are usually used in such reactions. These may be soluble catalysts such as protic acids e.g. hydrogen fluoride or sulphuric or phosphoric acids, or insoluble catalysts such as zeolites or heteropoly acids from Mo or W. The alkylates usually have a boiling range with IBP of at least 15°C and FBP in the range 170-210°C, e.g. 175-190 or 185-205°C. The refinery stream for use in the compositions of the invention is preferably made as a distillation cut from said material e.g. alkylate, the cut being at 15-60 (e.g. 30-60), 60-80, 80-90, 90-95, 95-100, 100-103, 103-106, 106-110, 1 10-1 15, 1 15-125, 125-140 or 140-160°C; a blend of different cuts may be used e.g. 15- 60, with at least one of 60-80, 80-90, 90-95 and 95-100 or 60-80 with at least one of 80- 90, 90-95, 95-100, 100-103 or 103-106°C or a combination e.g. 80-106 or 90-106°C. Preferably the cut is of product distilled from alkylate over a temperature range of 15- 160° or 15-140°C, especially 15-100 or 30-100°C or 60-160°C, 60-140 e.g. 60-100 or 90-125°C. Cuts with temperatures in the range 15-160°C especially 90-125°C or 15-100°C such as 60-100°C have been found to give unleaded gasolines which on combustion gave reduced total hydrocarbon emissions and reduced carbon oxide, e.g. CO 2 emissions, compared to those from whole alkylate or in particular cuts above 160°C. The cut from alkylate above 160°C can be used in jet fuel, diesel or kerosene, while the cut from alkylate from 160°C or 100°C downwards can be used in gasolines. Cuts of 60- 160°C can be used in summer gasolines because of their reduced Reid Vapour Pressure. Cuts below 100°C can also be used to boost the volatility of unleaded gasolines e.g. to help provide gasolines with % evaporated at 100°C values of at least 46. Advantageously the cut has a boiling range of at least part of 90-106°C, e.g. 90-95, 95-100, 100-103 or 103-106°C, as these give optimum octane rating coupled with good emissions. These cuts may be used as such in the compositions and gasolines of the invention but may be mixed with at least one cut of higher bp e.g. 106-110, 110-115, 115-125 or 125-140°C such as 106-125°C (preferably in proportion of 5: 1 to 1 :30 or at least one cut of lower bp e.g. 60-80 or 80-90, such as 60-90°C (preferably in proportions of 9: 1 to 1 :9 such as 5: 1-1 : 1). Preferably however the cut in at least part of bp 90-106°C is used as sole or main component (a) in the compositions, gasolines and uses of this invention with component (g); these can provide clean high octane unleaded gasolines, in particular ones free of oxygenate, with RON value of at least 97 and MON value at least 86 with low emissions. Example of such compositions and gasolines are those with RON, 97-99.5 or 97.5-99, MON 86.5-89, RVP 55-65 kPa e.g. 55-60 kPa, % evaporated at 70°C, 12-35%, % evaporated at 100°C 46-62%, % evaporated at 150°C 95-100%, % evaporated at 180°C 97.5-100%, density 0.715 to 0.74 e.g. 0.72-0.738 kg/1, benzene 0.5-1.5% e.g. 0.5-1%, aromatics 16-28% e.g. 16-23%, olefins 3-14% such as 4-12%. They may be made from mixtures of butane 0 or 0.5-6.6%, full boiling range alkylate 1-25% e.g. 5-20%, light hydrocrackate 0 or 15-25%, full range steam cracked spirit 10-45% naphtha 0 or 0.5- 5%, full range catalytically cracked spirit 0 or 1-5% 2,2,4 trimethylpentane 0 or 0.5-25% such as 0.5-5%, and alkylate cut(s) usually in total amount 25-45%. The amounts of the latter may be cut bp (90-95, 95-100, 100-103, 103-106°C) used alone 25-45%, or blends of one or more of those cuts 1-40% (in total in overall composition) and 5-40% of cuts bp 15-60, 60-80 (especially 3-15%) bp 106-1 10, 1 10-1 15, 115- 125°C (especially 7-40%, e.g. 7-20%). In addition the remaining cuts i.e. those above and below the 90-106°C cut especially those boiling in part of the 15-80°C range and those boiling in part of the 106- 125°C range, can be combined e.g. in proportion 5: 1-1 :5, and the combination used as component (a) in composition, gasolines and uses of this invention with component (g); these can provide clean lower octane unleaded gasolines, in particular ones free of oxygenates, with RON values of at least 92 and MON values of at least 80 also with low emissions. Example of such compositions and gasolines made from a blend of high and low bp cuts are those with RON 92-98 e.g. 92-95 or 95-98, MON 80-88 e.g. 80-84 or 84-88, RVP 50-65 kPa e.g. 50-55 or 55-60 kPa, % evaporated at 70°C, 12-35%, % evaporated at 100°C 46-62%, % evaporated at 150°C 94-100%, % evaporated at 180°C 97.5-100%, density 0.715 to 0.74 e.g. 0.72-0.738 kg/1, benzene 0.5-1.5% e.g. 0.5-1%, aromatics 13-28% e.g. 13-20%, olefins 3-14% such as 3-10%. They may be made from mixtures of butane 0 or 0.5-3%, full boiling range alkylate 10-40% e.g. 15-30%, full range steam cracked spirit 15-50% e.g. 15-35%, naphtha 0 to 10-20%, and alkylate cut(s) usually in total amount 25-45%. The amounts of the latter may be 5-25% (in total of the overall composition) of one or more of cuts of 15-60, 60-80 and 80-90°C and 10- 30% in total (of the overall composition) of cuts of 106-110, 110-115, 115-125°C especially 110-125°C. By this means, substantially all the alkylate can be converted into 2 clean fuel products of higher and lower octane level. Thus in a further aspect the present invention also provides a process for preparing at least 2 clean compositions suitable for production of gasolines, which comprises fractionating a reaction product comprising a majority of isoalkanes e.g. isomerization or alkylation product e.g. of bp 15-160°C to produce a first cut boiling in at least part of the range 90-106°C, and a second cut boiling at a temperature lower than said first cut and third cut boiling at a temperature above said first cut, blending said first cut as component (a) with component (g) as defined above to produce a first high octane unleaded gasoline composition of RON at least 97 and MON value at least 86 with low emissions on combustion, and incorporating said second and third cuts as component (a) with component (g) as defined above to produce at least one second high octane unleaded gasoline composition of RON at least 92 and MON value at least 80 with low emissions on combustion. In both cases these gasolines can be obtained without the need of oxygenate octane booster. The present invention also provides a method of producing fuels which comprises distilling said reaction product e.g. alkylale to produce a first cut above 160°C and a second cut below 160°C, and mixing said first cut with other liquid hydrocarbon blend ingredients to form a jet fuel, diesel or kerosene, and mixing said second cut with other liquid gasoline blend ingredients to form motor gasoline. Component (g) present in the compositions of the invention is usually at least one paraffin, aromatic and/or olefinic hydrocarbon of bp less than 160°C. Examples of said components are components (b)-(f) below, each of which or 2 or more of which may be present. In the second aspect of the invention, examples of the branched chain alkane (usually of 4-12 e.g. 4-8 carbons) which is component (a) are iso alkanes of 4-8 carbons, in particular isobutane, isopentane and isooctane, and dimethyl alkanes, such as 2,3- dimethyl butane. The branched chain alkane usually has at least one, preferably two methyl groups on carbon atom 2 in the alkane chain. The branched alkane usually provides at least 30% e.g. 30-80%, such as 50-80% of the total saturated content of the composition or of the total saturated content of the alkylation cut, the remainder being substantially other branched chain alkanes not meeting the specified definition e.g. of bp of 100-160°C, or lower MON value and/or linear hydrocarbons e.g. of 4-8 carbons as described above. Small amounts of cycloalkanes as described above may also be present in the saturate content. The compositions of the invention usually contain less than 5% triptane or 223 trimethyl pentane, especially less than 4.9% or 1%, and in particular are substantially free of triptane and 223 trimethyl pentane (e.g. with less than 0.5% or 0.1% in total of both if present). However, if desired and especially with cuts boiling above 60°C e.g. 60-160 or 60-100°C, triptane and/or 223 trimethyl pentane may be present in amount of at least 5 or 8%> such as 5-20% in the composition. In the composition of the invention, component (g) may be component (b) which is at least one saturated liquid aliphatic hydrocarbon having 4 to 12, 4-10 such as 5-10 e.g. 5 - 8 carbon atoms. In another embodiment component (b) is contained in at least one of isomerate, full range alkylate with FBP more than 170°C, straight run gasoline, light reformate, light hydrocrackate and aviation alkylate. Preferably the composition comprises at least one of an olefin (e.g. in amount of 1-30% e.g. 8-18%) and/or at least one aromatic hydrocarbon (e.g. in amount of 1-50%, especially 3-35%) and/or less than 5% of benzene. The composition may preferably comprise 5-40% component (a), less than 1% benzene and have a Reid Vapour Pressure at 37.8°C measured according to ASTMD323 of 30-120kPa. The composition is usually an unleaded motor gasoline base blend composition. The branched chain alkanes e.g.compounds A may be alkanes of 8-12 carbon atoms (especially 8-10 or 8 or 10 carbons) with 3 methyl and/or ethyl branches. Methyl branches are preferred. The compounds usually have their longest chain of carbon atoms, hereinafter called their backbone chain, with 4-6 chain carbon atoms (especially 4 or 5) to which the methyl, and/or ethyl branches are attached. Advantageously, especially in relation to the first to tenth groupings as described further below, there are no branched groups constituting the branches other than methyl or ethyl, and, in the backbone chain of carbon atoms, there are especially no linear alkyl groups of more than 2 carbons nor 1,2 ethylene or 1,3 propylene groups in the chain, and especially no methylene groups in the chain except as part of an ethyl group; thus there are especially no n-propyl or n-butyl groups forming part of the backbone chain. Preferably, when in the composition there is at least one compound (A) alkane of 9-12 e.g. 9 or 10 carbons, there is usually as well less than 50% or 10% of an 8 carbon alkane compound (A). The compounds can have 1 or 2 methyl or ethyl groups attached to the same carbon atom of the backbone chain, especially 1 or 2 methyl groups and 0 or 1 ethyl groups. The carbon atom in the backbone at which the branching occurs is non-terminal i.e. is an internal carbon in the backbone chain, especially the 2, 3 and/or 4 numbered carbon in the backbone. Thus advantageously the compound has geminal methyl substituents on position 2, 3 or 4 carbon atom, especially position 2, but in particular position 3. In a first grouping of compounds A, there is one pair of geminal methyl branch substituents, and they are on position 2. In a second grouping of the compounds A there is 1 pair of geminal methyl branch substituents on a 4-6 carbon chain backbone. The compounds of the second grouping advantageously have a MON value of at least 100. In a third grouping of the compounds, there is one geminal methyl branch grouping i.e. -CMe 2 - on the backbone, while on one of the adjacent carbon atoms of the backbone, there is a methyl or ethyl branch, especially a methyl branch. In a fourth grouping of the compounds there is one pair of geminal methyl branches on the 2 position backbone carbon and there is a methyl branch on the 3 position backbone carbon. Such compounds usually have a RON value of at least 111. Advantageously the compounds are of 8 or 10 carbon atoms. In a fifth grouping the compound A has 3 methyl or ethyl substituents on different back bone carbon atoms, especially on vicinal carbon atoms. In a sixth grouping the compounds have a linear backbone chain of 4 or 6 carbons and have 3 methyl branches, one pair of which is one geminal group (CMe ) especially in the absence of a 1,2 ethyl group in the backbone. In a seventh grouping, the compounds have a linear backbone chain of 5 or 6 carbons and have 3 branches one pair of which is in one geminal group, are usually liquid at 25°C and generally have a RON value of greater than 105. Especially there are only methyl branches; such compounds usually have a MON value of at least 101. Advantageously in an eighth grouping the compounds A contain 1 chain carbon atoms with geminal methyl branches, with one branch on the vicinal carbon atom to the geminal one, and any ethyl -C- chain group in the backbone chain has 5 carbon atoms i.e. is (Ethyl) 2 CH or Ethyl CMe 2 -. A particularly preferred sub-class (ninth grouping) for the compound A is alkanes with 3 methyl or ethyl substituents which are (i) on vicinal internal carbon atoms, with a total of 4, 5 or 6 carbon atoms in said substituents. Or (ii) with a total of 3 carbon atoms in said substituents and a one terminal CHMe 2 group. Or (iii) with a total of 3 carbon atoms in said substituents and contain only secondary internal carbon atoms in the longest carbon atom chain. Among this sub-class are preferred (i) and (ii) and especially with geminal methyl groups on an internal chain carbon atom. In another aspect of the invention there is provided an unleaded blend composition having a MON value of at least 81 or 85 and RON value of at least 91 or 94, which comprises component (a) a total of at least 15% of one or more branched alkane compounds A 1 of 8-12 carbons (especially with 4-6 backbone carbon atoms), with 3 methyl or ethyl branches and at least 2 backbone carbon atom which are secondary and/or tertiary carbon atoms, (subject of course to there being not more than one tertiary backbone carbon atom) with the proviso that if there are only 2 such carbon atoms, then one is tertiary, there being a minimum of at least 10% (by volume of the composition) of at least one individual compound A 1 , and component (b) of nature and in amount as described herein, with the preferred proviso as described above. In the above component A 1 , which may be the same or different from A, there may thus in a tenth grouping be in the backbone internal (i.e. non-terminal) carbon atoms which are (i) 1 tertiary and 1 sec, in particular (ii) with the tert and a sec. carbon vicinal or (iii) 1 tertiary 1 sec. and 1 primary especially with vicinal tert and sec. carbons or vicinal or non-vicinal sec. carbons or (iv) 3 sec. carbons, with at least 2 e.g. 3 vicinal. The compounds A 1 usually are free from 2 primary internal backbone carbon atoms on vicinal carbons i.e. as in 1,2-ethylene group. Preferably any primary internal backbone carbon atoms are not between, e.g. adjacent on both sides to, a tert. and/or sec. carbon on the one hand and a sec. carbon on the other hand. Especially at least the said 2 backbone carbon atoms above in compounds A 1 are vicinal. In another category, the eleventh grouping is of compounds A 1 which contain (with proviso that they only have 3 branched groups )(i) as one end of the backbone a group of formula CHR'R 2 where each of R 1 and R 2 , which are the same or different is a methyl or ethyl group or (ii) as one end of the backbone a group of formula CR L R 2 R 3 where R 1 and R 2 are as defined above and R 3 is methyl or ethyl. Preferred are such compounds A 1 which have both (i) and (ii), especially when the CHR'R 2 group is CHMe 2 when the compound has 8 carbons or a backbone of 5 carbons and when all internal carbon atoms in the backbone chain are secondary or tertiary (subject to a total of 3 branched groups). The compounds A or A 1 may have a boiling point at 1 bar pressure of 129-150°C 1 10-129°C, or 90-109°C. In particular the boiling point is preferably at least 105°C e.g. 105-175°C, with the proviso that compound A or A 1 is Not 223 trimethyl pentane or is at least 112°C such as 112-175°C. In another category the compounds A or A 1 may have 3 methyl and/or ethyl branches on a 4-6 carbon backbone, and especially a ratio of carbon atom in branches to carbon atoms in the backbone chain of at least 0.55: 1 e.g. 0.55-0.9: 1 such as 0.63-0.9: 1. The compounds usually have 9 carbons, unless the above ratio is at least 0.63 or 0.75. Preferred compounds are 223 trimethyl pentane (A3), 224 trimethyl pentane (isooctane) (A4) 22 Me 2 3 ethyl pentane (A5), 233 trimethyl pentane (A6) 24 dimethyl 3 ethyl pentane (A8), and 234 trimethyl pentane (A9). The branched hydrocarbon may also not be 224 trimethyl pentane and/or 223 trimethyl pentane. The compounds A and A 1 are either known compounds and may be made according to the published literature, or are novel and may be made by conventional methods known per se in the literature (e.g. as described in Kirk Othmer Encyclopaedia of Chemical Technology 3rd Ed. Publ. Wiley). Examples of suitable methods of preparation are known carbon-carbon coupling techniques for making alkanes. The technique may involve reactions of one or more usually 1 or 2 alkyl chlorides, bromides or iodides with an elemental metal of Group IN UN IB or IIB of the Periodic Table in Advanced Inorganic Chemistry by F.A.Cotton + G.wilkinson, Pub. Interscience New York 2nd Ed. 1966, especially sodium, magnesium, or zinc. The alkyl halide is usually a branched chain one of 3-6 carbons, in particular with methyl or ethyl branches, and especially with the halogen atom attached to a CMe 2 group in one of the alkyl halides. Preferably a halide is of formula MeCMe 2 X or EtCMe 2 X, where X is CI, B or I and the other halide is a secondary halide e.g. of formula RR'CH-X where each of R and R 1 is methyl or ethyl, such as isopropyl or sec butyl or sec amyl halide or a primary branched alkyl halide e.g. of formula R π CH 2 X, where R 11 is a branched alkyl group 3-5 carbons with methyl or ethyl branches, such as isopropyl, isobutyl or isoamyl. Alternatively both halides can be secondary e.g. of formula RR'CHX, as defined above and R^'R^CHX where R 111 is methyl or ethyl and R™ is as defined for R 11 , such as isopropyl or one can be secondary (as above) and one can be primary e.g. methyl or ethyl halide. The methods of coupling optimum for any particular compound A or A 1 depend on availability of the precursor alkyl halide(s) so that in addition to the above kinds, coupling via methyl or ethyl halides with branched alkyl halides of 6-9 carbons may also be used. The alkyl halide(s) can react together in the presence of the metal (as in a Wurtz reaction with sodium), or one can react first with the metal to form an organometallic compound e.g. a Grignard reagent or organo zinc, followed by reaction of the organometallic with the other alkyl halide. If desired the Grignard reagent reaction can be in the presence of a metal of Group IB or IIB, such as silver, zinc or copper (especially high activity copper). If desired the Grignard reagent from one or both alkyl halides can be reacted with the latter metal to form other alkyl metallic species e.g. alkyl silver or alkyl copper compounds, which can disproportionate to the coupled alkane. The Grignard reagent(s) can also react with a cuprous halide to form alkyl copper species for disproportionation. Finally an organometallic compound, wherein the metal is of Group IA or IIA e.g. Li or Mg can be coupled by reaction with a cuprous complex to give a coupled alkane. The above organometallic reactions are usually conducted under inert conditions, i.e. anhydrous and in the absence of oxygen e.g. under dry nitrogen. They are usually performed in an inert solvent e.g. a dry hydrocarbon or ether. At the end of the reaction any residual organometallic material is decomposed by addition of a compound with active hydrogen e.g. water or an alcohol, and the alkanes are distilled off, either directly or after distribution between an organic and aqueous phase. Examples of preparations of highly branched alkanes are described in F L Howard etal, J Res. Nat. Bur. Standards Research Paper RP1779, Vol 38 March 1947 pp 365- 395. The disclosures of is document is incorporated herein by reference. The crude alkanes made by the above processes may be used as such in the blends of the invention or may be purified further e.g. by distillation first. If desired the compounds, especially of 8 carbon atoms may be obtained by fractional distillation of refinery streams e.g. straight run gasolines, or alkylation products e.g. of isoalkanes of 3-5 carbons with alkanes of 3-5 carbons (as described above) Other known methods of making the alkanes A or A 1 , are reaction of alkyl metallic compounds e.g. Grignard reagents with carbonyl compounds such as aldehydes, ketones, esters, or anhydrides to form branched chain carbinols, which are dehydrated to the corresponding olefin, which is hydrogenated to the alkane. Thus 2,3,4-trimethyl pentane may be made from isopropyl magnesium bromide and methyl isopropyl ketone (followed by dehydration and hydrogenation), and 2,2-dimethyl 3 ethyl pentane, from ethyl magnesium chloride and di isopropyl ketone. The present invention also provides an unleaded formulated motor gasoline which comprises said composition of the first to seventh aspects of the invention and at least one gasoline additive e.g. motor or aviation gasoline additive- The component (a) may be present in amount of 5-95% or 8-90% such as 10- 90%, or 15-65% e.g. 20-55% or 10-40% such as 20-35% by volume or 40-90% such as 40-55% or 55-80% or 8-35% such as 8-20% by volume. Unless otherwise stated all percentages in this specification are by volume, and disclosures of a number of ranges of amounts in the composition or gasoline for 2 or more ingredients includes disclosures of all sub-combinations of all the ranges with all the ingredients. The invention in its first to fourth aspects will be further described with alkylate cuts exemplifying the refinery stream component (a) but others may be used instead or as well. The composition of the invention may also contains as component (b) at least one liquid saturated hydrocarbon of 5-10 carbons especially predominantly branched chain C 7 or C 8 compounds e.g. iso C 7 or iso C 8 . This hydrocarbon may be substantially pure e.g. n-heptane, isooctane or isopentane or a mixture e.g. a distillation product or a reaction product from a refinery reaction e.g. alkylate. The hydrocarbon may have a Motor Octane Number (MON) of 0-60 but preferably has a MON value of 60-96 such as isomerate (bp 25-80°C). Research Octane Number RON may be 80-105 e.g. 95-105, while the ROAD value (average of MON and RON) may be 60-100. Component (b) which is different from component (a) may comprise a hydrocarbon component having boiling point (preferably a final boiling point) of at least 82°C, such as 85-150°C but less than 225°C e.g. less than 170°C or 160°C and usually is of Motor Octane Number of at least 92 e.g. 92-100; such components are usually alkanes of 7-10 carbons especially 7 or 8 carbons, and in particular have at least one branch in their alkyl chain, in particular 1-3 branches, and preferably on an internal carbon atom and especially contain at least one -C(CH 3 ) - group. The volume amount of the component (b) in total (or the volume amount of mixtures comprising component (b), such as the total of each of the following (if present) (i)-(iv)) (i) catalytic reformate, (ii) heavy catalytic cracked spirit, (iii) light catalytic cracked spirit and (iv) straight run gasoline in the composition is usually 10-80%) e.g. 25-70%, 40-65% or 20-40%, the higher percentages being usually used with lower percentages of component (a). Component (b) may be a mixture of the liquid saturated hydrocarbons e.g. a distillation product e.g. naphtha or straight run gasoline or a reaction product from a refinery reaction e.g. alkylate including full range alkylate (bp 30-190°C) isomerate (bp 25-80°C), light reformate (bp 20-79°C) or light hydrocrackate. The mixture may contain at least 60% or at least 70% w/w e.g. 60-95 or 70-90% w/w liquid saturated aliphatic hydrocarbon. The compositions of the invention may contain mixtures of component (a) e.g. alkylate cut of 15-100°C with full range boiling alkylate (i.e. of FBP greater than 170°C e.g. 190°C) in a ratio of 9: 1 to 1 :9 in particular 5-9:5-1 or 1-3:9-7. If desired such mixtures may be made by dividing the full range alkylate into first and second portions, a first portion being distilled to provide the desired cut and then the cut mixed with the second portion. The residue from the cut can be used elsewhere as described above. Volume amounts in the composition of the invention of the component (b) mixtures (primarily saturated liquid aliphatic hydrocarbon fractions e.g. the total of isomerate, full range alkylate, naphtha and straight run gasoline (in each case (if any) present in the composition) may be 4-60%, such as 4-25% or preferably 10-55% such as 25-45%. Full range alkylate or straight run gasoline are preferably present for component (b), optionally together but preferably in the absence of the other, in particular in amount of 2-50% such as 10-45 e.g. 10-25%, 25-45% or 25-40%. The compositions of the invention may also comprise naphtha e.g. in volume amount of 0- 25% such as 2-25%, 10-25% or 2-10%. The compositions may comprise as component (c) a hydrocarbon component which is a saturated aliphatic hydrocarbon of 4-6 carbons and which has a boiling point of less than 80°C under atmospheric pressure, such as 20-50°C, and especially is itself of Motor Octane Number greater than 88 in particular at least 90 e.g. 88-93 or 90-92. Examples of the hydrocarbon component include alkanes of 4 or 5 carbons in particular iso-pentane, which may be substantially pure or crude hydrocarbon fraction from reformate or isomerate containing at least 30% e.g. 30-80% such as 50-70%, the main contaminant being up to 40% mono methyl pentanes and up to 50% dimethyl butanes. The hydrocarbon component may be an alkane of boiling point (at atmospheric pressure) -20°C to +20°C e.g. n and/or iso butane optionally in blends with the C 5 alkane of 99.5:0.5 to 0.5:99.5, e.g. 88: 12 to 75:25. n Butane alone or mixed with isopentane is preferred, especially in the above proportions, and in particular with a volume amount of butane in the composition of up to 20% such as 1-15% e.g. 1-8, 3-8 or 8-15%. Cycloaliphatic hydrocarbons e.g. of 5-7 carbons such as cyclopentane or cyclohexane may be present but usually in amounts of less than 15% of the total e.g. 1- 10%. Volume amounts in the composition of the total of isomerate, full range alkylate, naphtha, straight run gasoline, 4-6 carbon liquid aliphatic hydrocarbon (as defined above) and cycloaliphatic hydrocarbon (in each case if present) may be 5-60%, such as 8-25%, 15-55% such as 30-50%. The compositions of the invention also preferably contain as component (d) at least one olefin, (in particular with one double bond per molecule) which is a liquid alkene of 5-10 e.g. 6-8 carbons, such as a linear or branched alkene e.g. pentene, isopentene hexene, isohexene or heptene or 2 methyl 2 pentene, or a mixture comprising alkenes which may be made by cracking e.g. catalytically or thermally cracking a residue from crude oil, e.g. atmospheric or vacuum residue; the mixture may be heavy or light catalytically cracked spirit (or a mixture thereof). The cracking may be steam assisted. Other examples of olefin containing mixtures are "C6 bisomer", catalytic polymerate, and dimate. The olefinic mixtures usually contain at least 10% w/w olefins, such as at least 40% such as 40-80% w/w. Preferred mixtures are (xi) steam cracked spirit (xii) catalytically cracked spirit (xiii) C6 bisomer and (xiv) catalytic polymerate, though the optionally cracked catalytically spirits are most advantageous. Amounts in the total composition of the olefinic mixtures especially the sum of (xi) - (xiv) (if any present) maybe 0-55, e.g. 10-55 or 18-37 such as 23-35 or 20-55 such as 40-55% or 23-40% Amounts of (xi) and (xii) (if present) in total in the composition are preferably 18-55, such as 18-35, 18-30 or 35-55% (by volume). The olefin or mixture of olefins usually has an MON value of 70-90, usually a RON value of 85-95 and a ROAD value of 80-92. The volume amount of olefin(s) in total in the gasoline composition of the invention may be 0% or 0-30%, e.g. 0.1-30% such as 1-30% in particular 2-25, 5-30, (especially 3-10), 5-18.5, 5-18 or 10-20%. Preferably the composition contains at least 1% olefin and a maximum of 18% or especially a maximum of 14%, but may be substantially free of olefin. The compositions may also contain as component (e) at least one aromatic compound, preferably an alkyl aromatic compound such as toluene or o, m, or p xylene or a mixture thereof or a trimethyl benzene. The aromatics may have been added as single compounds e.g. toluene, or may be added as an aromatics mixture containing at least 30% w/w aromatic compounds such as 30-100% especially 50-90%. Such mixtures may be made from catalytically reformed or cracked gasoline obtained from heavy naphtha. Example of such mixtures are (xxi) catalytic reformate and (xxii) heavy reformate. Amounts of the single compounds e.g. toluene in the composition may be 0- 35%, such as 2-33% e.g. 10-33%, while amounts of the aromatics mixtures especially the total of the reformates (xxi) & (xxii) (if any) in the composition may be 0-50%, such as 1-33% e.g. 2-15% or 2-10% or 15-32% v/v, and total amount of reformates (xxi), (xxii) and added single compounds (e.g. toluene) may be 0-50% e.g. 0.5-20% or 5-40, such as 15-35 or 5-25% v/v. The aromatics usually have a MON value of 90-1 10 e.g. 100-1 10 and a RON value of 100- 120 such as 110-120 and a ROAD value of 95-1 10. The volume amount of aromatic compounds in the composition is usually 0% or 0-50% such as less than 40% or less than 28% or less than 20% such as 1-50%, 2-40%, 3-28%, 4-25%, 5-20% (especially 10-20%), 4-10% or 20-35% especially of toluene. The gasoline composition may also be substantially free of aromatic compound. -Amounts of aromatic compounds of less than 42%, e.g. less than 35% or especially less than 30% are preferred. Preferably the amount of benzene is less than 5% preferably less than 1.5% or 1% e.g. 0.1-1% of the total volume or less than 0.1% of the total weight of the composition. The compositions may also contain as component (f) at least one oxygenate octane booster, usually of Motor Octane Number of at least 96-105 e.g. 98-103. The oxygenate may be any organic liquid molecule containing and preferably consisting of, CH and at least one oxygen atom e.g. 1-5 of bp less than 225°C. The octane booster is usually an ether e.g. a dialkyl ether, in particular an asymmetric one, preferably wherein each alkyl has 1-6 carbons, in particular one alkyl being a branched chain alkyl of 3-6 carbons in particular a tertiary alkyl especially of 4-6 carbons such as tert-butyl or tert-amyl, and with the other alkyl being of 1-6 e.g. 1-3 carbons, especially linear, such as methyl or ethyl. Examples of such oxygenates include methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether and methyl tertiary amyl ether. The oxygenate may also be an alcohol of 1-6 carbons e.g. ethanol. The oxygenate may also be an organic carbonate e.g. a dialkyl carbonate with 1-3 carbon atoms in each alkyl e.g. dimethyl carbonate. The volume amount of the oxygenate may be 0 or 0-25% such as 1-25%, 2-20%, 2-10% or 5-20% especially 5-15%, but advantageously less than 3% such as 1-3% (especially of MTBE and/or ethanol). The oxygenate may also be substantially absent from the composition or gasoline of the invention. Thus the present invention produces an unleaded blend composition of MON value at least 81 or 85 and RON value at least 91 or 94 which comprises (a) a total of at least 15% of one or more branched hydrocarbon compound A or A 1 there being a minimum of at least 5% of at least one individual compound A or A 1 and (b) at least 20% of at least one different liquid hydrocarbon of bp60-160°C having a MON value of at least 70 and RON value at least 90 especially when (b) is not within the definition of A or A 1 , in particular when (a) is a trimethyl pentane. Examples of the liquid hydrocarbons are paraffins, such as linear or branched chain alkanes of 4-8 carbons, such as isobutane, butane, isopentane, dimethyl alkanes such as 23 dimethyl butane, cycloalkanes, such as cyclopentane and cyclohexane, aromatics and olefins. Another unleaded blend composition of the invention of MON value of at least 81 or 85 and RON value of at least 91 or 94 comprises component (a) as above and component (b) at least 20% of at least one of a straight run naphtha, alkylate isomerate (bp25-80°C) heavy reformate, light reformate (bp20-79°C), hydrocrackate, aviation alkylate (bp30-190°C), straight run gasoline, cracked spirit, such as heavy or light catalytic cracked spirit or steam cracked spirit. The straight run products are produced directly from crude oil by atmospheric distillation. The naphtha may be light naphtha of bp30-90°C or medium naphtha of bp90-150°or heavy naphtha of bpl50-220°C. In the blends of the invention, the amount of at least one individual compounds A or A 1 is usually at least 5%, or at least 10 or 15%, such as 5-60%, e.g. 15-60%, or 8- 25%, 20-35% or 30-55% or 2-10%. The amount of compound A4 if present is usually at least 10% of the composition. Total amounts of trimethyl pentanes in the blend are preferable less than 69% of the blend, but advantageously at least 26% (especially when the amount of aromatics is less than 17%. If a 9 or 10 carbon alkane is (a), then the amount of 2,2,4-trimethyl pentane is especially less than 70 or 50%. More than one such compound A or A 1 may be present e.g. of higher and lower RON in weight ratios of 9: 1 to 0.5:99.5, such as 0.5: 1 to 5: 1 or 5:95 to 20:80, particularly for mixtures of compounds with higher or lower boiling points (atmospheric pressure) e.g. those in which the compounds A and/or A 1 have boiling points differing by at least 10°C e.g. at least 40°C such as 10-70°C or 20-50°C the relative amounts being as described above. Total amounts of all compounds A and A 1 (if any) in the blend may be 15-70 e.g. 15-60, 15-40 or 30-55% or 40-60%. The blend may also comprise predominantly aliphatic refinery streams such as naphtha, straight run gasoline (also known as light naphtha bp 25-120°C), alkylate and isomerate. Amounts in total of these may be 10-70%, such as 10-30, 30-70 or 35-65%. Amounts of naphtha may be 0-70% or 1-70% such as 10-30, 30-70 or 35-65%, while amounts of light naphtha may be 0 or 1-70 such as 1-20 or especially 30-65%, and amounts of medium naphtha may be 0 or 1-55, such as 3-20 or 15-55%. The volume ratio of light to medium naphtha may be 50:1 to 1 :50, such as 0.5-20: 1 or 1 :0.5-50. Amounts of alkylate or isomerate (if present) may be 0.5-20% such as 1-10%, while amounts of hydrocrackate may be 0.5-30% e.g. 10-30%. The blends of the invention usually contain in total at least 70% of saturates, such as 70-98% or 70-90% or 90-98%. If desired and especially for aviation gasoline, the blends may contain a hydrocarbon component which is a saturated aliphatic hydrocarbon of 4-6 carbons and which has a boiling point of less than 80°C under atmospheric pressure, such as 20-50°C, and especially is itself of Motor Octane Number greater than 88 in particular at least 90 e.g. 88-93 or 90-92. Examples of the hydrocarbon component include alkanes of 4 or 5 carbons in particular iso-pentane, which may be substantially pure or crude hydrocarbon fraction from reformate or isomerate containing at least 30% e.g. 30-80% such as 50- 70%, the main contaminant being up to 40% mono methyl pentanes and up to 50% dimethyl butanes. The hydrocarbon component may be an alkane of boiling point (at atmospheric pressure) -20°C to +20°C e.g. n and/or iso butane optionally in blends with the C 5 alkane of 99.5:0.5 to 0.5:99.5, e.g. 88: 12 to 75:25. n Butane alone or mixed with isopentane is preferred, especially in the above proportions, and in particular with a volume amount of butane in the composition of up to 20% such as 1-15% e.g. 1-8, 3-8 or 8-15%, especially 1-3.5%. The hydrocarbon component boiling less than 80°C, in particular isopentane, may also be present in compositions of the invention which contain at least one compound A or A of at least 10 carbon atoms. Relative amounts of these compounds A or A 1 to the low boiling component e.g. isopentane, may be 1-9:9-1 such as 5-9:5-1, especially with less than 20% of A or A 1 in the composition. Cycloaliphatic hydrocarbons e.g. of 5-7 carbons such as cyclopentane or cyclohexane may be present but usually in amounts of less than 15% of the total e.g. 1- 10%. The blend of the invention contains at least one component (a) and component (g) and, (optionally (c) to (f), as well, and the formulated unleaded gasoline also contains at least one gasoline additive e.g. a motor gasoline or aviation gasoline additive, for example as listed in ASTM D-4814 the contents of which is herein incorporated by reference or specified by a regulatory body, e.g. US California Air Resources Board (CA-RB) or Environmental Protection Agency (EPA). These additives are distinct from the liquid fuel ingredients, such as MTBE. Such additives may be the lead free ones described in Gasoline and Diesel Fuel Additives, K Owen, Publ. By J.Wiley, Chichester, UK, 1989, Chapters 1 and 2, USP 3955938, EP 0233250 or EP 288296, the contents of which are herein incorporated by reference. The additives maybe pre-combustion or combustion additives. Examples of additives are anti-oxidants, such as one of the amino or phenolic type, corrosion inhibitors, anti-icing additives e.g. glycol ethers or alcohols, engine detergent additives such as ones of the succinic acid imide, polyalkylene amine or polyether amine type and anti-static additives such as ampholytic surface active agents, metal deactivators, such as one of thioamide type, surface ignition inhibitors such as organic phosphorus compounds, combustion improvers such as alkali metal salts and alkaline earth metal salts of organic acids or sulphuric acid monoesters of higher alcohols, anti valve seat recession additives such as alkali metal compounds, e.g. sodium or potassium salts such as borates or carboxylates e.g. sulpho succinates, and colouring agents, such as azodyes. One or more additives (e.g. 2-4) of the same or different types may be used, especially combinations of at least one antioxidant and at least one detergent additive. Antioxidants such as one or more hindered phenols e.g. ones with a tertiary butyl group in one or both ortho positions to the phenolic hydroxyl group are preferred in particular as described in Ex.1 hereafter. In particular the additives may be present in the composition in amounts of 0.1-lOOppm e.g. l-20ppm of each, usually of an antioxidant especially one or more hindered phenols. Total amounts of additive are usually not more than lOOOppm e.g. 1-lOOOppm. The compositions and gasolines are free of organolead compounds, and usually of manganese additives such as manganese carbonyls. The compositions and gasolines may contain up to 0.1% sulphur, e.g. 0.000- 0.02% such as 0.002-0.01%w/w. The motor gasoline compositions of the invention in particular those based on the distillation cuts e.g. alkylate cuts usually have a MON value of 80 to less than 98, such as 80-95, 83-93, 85-90 or 93-98. The RON value is usually 90-115 e.g. 102-115 or preferably 90-102 preferably 90-100 e.g. 90-99, such as 90-93 e.g. 91, or 93-98 e.g. 94.5-97.5, or 97-101 while the ROAD value is usually 85-107 e.g. 98-106 or preferably 85-98 such as 85-95 e.g. 85-90, or 90-95 or 95-98. Preferred gasoline compositions have MON 80-83, RON 90-93, and ROAD 85-90, or MON 83-93, RON 93-98 and ROAD 85-95 or MON 85-90, RON 97-101 and ROAD 91-96. The Net calorific value of the gasoline (also called the Specific Energy) is usually at least 18000 Btu/lb e.g. at least 18500, 18700 or 18,900 such as 18500-19500, such as 18700-19300 or 18900- 19200; the calorific value may be at least 42MJ/kg e.g. at least 43.5 MJ/kg such as 42-45 or 43-45 such as 43.5 -44.5 MJ/kg. The gasoline usually has a boiling range (ASTM D86) of 20-225°C, in particular with at most 5% e.g. 0-5% or 1-3% boiling in the range 161-200°C. The gasoline is usually such that at 70°C at least 10% is evaporated while 50% is evaporated on reaching a temperature in the range 77-120°C preferably 77-116°C and by 185°C, a minimum of 90% is evaporated. The gasoline is also usually that 8-50% e.g. 10-50% may be evaporated at 70°C, 40-74% at 100°C,70-99.5% e.g. 70-97% at 150°C and 90-99% may be evaporated at 180°C; preferably at least 46% e.g. 46-65% has been evaporated by 100°C. The Reid Vapour Pressure of the gasoline at 37.8°C measured according to ASTM D323 is usually 30-120, e.g. 40-100 such as 61-80 or preferably 50-80, 40-65, e.g. 40-60 or 40-50Kpa. The unleaded motor gasolines of the invention preferably comprise the component (a) and have a RON value of at least 98, MON value of at least 87.8, an RVP of less than 60 K Pa e.g. 40-60 kPa less than 35% aromatics, less than 15% olefins, 10-45% evaporated at 70°C, 46-60% evaporated at 100°C, and more than 88% evaporated at 150°C. Their density is preferably at least 0.71 e.g. 0.71 to 0.78 such as at least 0.7122 or at least 0.72 such as 0.7122 to 0.7264 kg/1. The gasoline compositions of the invention in particular those based the branched chain alkanes for component (a) in particular in its fifth to seventh aspects usually have a MON value of 80 to 94 such as 85-90, or 90-94-. The RON value is usually 90-105 e.g. 98-102 , or 93-98 e.g. 94.5-97.5, or 97-101 while the ROAD value is usually 85-102 e.g. 98-102 or 85-95. Preferred gasoline compositions have MON 83-93, RON 93-98 and ROAD 85-95 or MON 85-90, RON 94-101 and ROAD 89-96. The Net calorific value of the gasoline (also called the Specific Energy is usually as described above as are the boiling ranges measured according to ASTM D86 and the RVP. The gasoline compositions, when free of any oxygenates usually have a H:C atom ratio of at least 1.8: 1 e.g. at least 2.0: 1 or at least 2.1 or 2.2: 1, such as 1.8-2.3: 1 or 2.0- 2.2: 1. Advantageously the gasoline composition meets the following criteria. Atom H:C x [1 + oxy] x [ Net Heat of Combustion + ROAD] > y, 200 wherein Atom H:C is the fraction of hydrogen to carbon in the hydrocarbons in the composition, oxy means the molar fraction of oxygenate, if any in the composition, Net Heat of Combustion is the energy derived from burning lib (454g) weight of fuel (in gaseous form) in oxygen to give gaseous water and carbon dioxide expressed in Btu/lb units [MJ/kg times 430.35], and y is at least 350, 380, 410 or 430, in particular 350-440 e.g. 380-420 especially 400-420. Preferably the motor gasoline of this invention comprises 10-90% of component (a), 10-80% of component (b), 0-25% naphtha, 0-15% of butane, 5-20% of olefin, 3- 28% aromatics and 0-25% oxygenate, in particular with 5-20% aromatics and 5-15% olefins. In a preferred embodiment of this invention the motor gasoline of this invention contains 8-65% of component (a) (especially 15-35%), 0.1-30% such as 2-25% olefins, especially 3-14% and 0-35% aromatics such as 0-30% e.g. 5-35, 5-20 (especially 5-15%) or 20-30%, and 5-50% component (b) mixtures e.g. 10-45% such as 20-40%. Such gasolines may also contain oxygenates, such as MTBE especially in amount of less than 3% e.g. 0.1-3% and especially contain less than 1.0% benzene e.g. 0.1-1% and especially olefins less than 18% e.g. 0.1-15%. Such gasolines preferably have RON of 96-99, MON 86-90 and ROAD values of 91-94.5. Examples of motor gasolines of the invention are ones with 5-25% component (a), 5-15% olefins, 15-35% aromatics and 40-65% component (b), in particular 15-25% component (a), 7-15%, olefins 15-25% aromatics and 45-52% component (b) mixture of RON value 96.5-97.5, or 5-15% component (a), 7-15% olefins, 15-25% aromatics and 55-65% compound (b) of RON value 94.5-95.5. Examples of motor gasolines of the invention are ones having 1-15% e.g. 3-12% butane, 0-20% e.g. 5-15% ether e.g. MTBE, 20-80 e.g. 25-70% of refinery mixed liquid (usually C 6 -C )streams (apart from naphtha) (such as mixtures of (i)-(iv) above), Q-25% e.g. 2-25% naphtha, 5-70% e.g. 15-65% component (a), with RON 93-100 e.g. 94-98, MON 80-98 e.g. 83-93 or 93-98, and RVP 40-80 such as 40-65Kpa. Such gasolines usually contain 1-30% e.g. 2-25% olefins and 2-30% e.g. 4-25% aromatics. Amounts of olefins of 15-25% are preferred for RON values of 94-98 e.g. 94-96 and 2-15% e.g. 2- 7% for RON values of 96-100 such as 96-98. Other examples of fuel compositions of the invention contain 8-18% component (a), 10-50% e.g. 25-40% of total component (b) mixture, 5-40% e.g. 20-35% of total aromatics mixture 15-60, e.g. 15-30% or 40-60% of total olefinic mixture and 0-15% total oxygenate e.g. 3-8% or 8-15%. Especially preferred compositions have 8-18% component (a), 25-40% total mixed component (b) mixture, 20-35% total aromatics, and 15-30%) total olefinics, or 8-18% component (a), 15-40% total mixed component (b) mixture, 3-25% total aromatics mixture, and 40-60% total olefinic mixture. Further examples of fuel compositions contain 20-40% component (a), 8-55% of the total component (b) mixture, e.g. 5-25% or 35-55%, and 0 or 5-25% e.g. 18-25% total aromatics mixture, 0-55 especially 10-55 or 40-55% total olefin mixture, especially preferred compositions having 20-40% component (a), 5-25% total component (b) mixtures, 3-25% total aromatics mixture and 40-60% total olefinic mixture, or 20-40%) component (a), 35-55% total component (b) mixture 15-30% total aromatics mixture and 0-15%) e.g. 5-15% total olefin mixture, or in particular 20-40% component (a), 25- 45% or 30-50%) total component (b) mixture, 2-15% total aromatics mixture 18-35%) total olefins mixture, and especially 3-10% or 5-18% olefins, and 10-35% such as 10- 20% aromatics (e.g. 10-18%). Other examples of fuel compositions contain 30-55% e.g. 40-55% component (a), 5-30% total component (b) mixture, 0-10% total aromatic mixture, 10-45% olefinic mixture and 0-15% oxygenates especially with the total of oxygenates and olefinic mixture of 20-45%. Other examples of fuel compositions contain 55-70% component (a), 10-45% total component b, e.g. 10-25% or 35-45%, and 0-10% e.g. 0 or 0.5-5% total aromatics Mixture, and 0-30% total olefinics mixtures, e.g. 0 or 15-30%, especially 55-70% component (a), 10-25% total component (b) 0 or 0.5-5% total aromatics mixture and 15-30% total olefinic mixture. Particularly preferred examples of fuel composition comprise 15-35% e.g. 20-35% component (a), 0-18.5% e.g. 2-18.5% olefin, 5-40% e.g. 5-35% aromatics 25-65% saturates and less than 1% benzene, and 18-65% e.g. 40-65% component (a), 0-18-5% e.g. 5-18.5% olefins, 5-42% e.g. 5-28% aromatics, 35-55% saturates and less than 1% benzene. Another fuel composition may comprise 25-40% e.g. 30-40% such as 35% of alkylate (especially full bp range alkylate with IBP 30°C or more and FBP greater than 165°C), 10-25% e.g. 15-25% such as 20% of isomerate, 10-25% e.g. 15-25% such as 20% of light hydrocrackate and 20-35% e.g. 20-30% such as 25% of component (a) and optionally 0-5% butane. Such a composition is preferably substantially paraffinic and is substantially free of olefins and aromatics. A further gasoline composition which provides a specific aspect of the present invention comprises 2-20% e.g. 5-15% component (a) especially an alkylate cut at 15- 100°C, 20-40% e.g. 25-35% full boiling range alkylate e.g. of FBP 175-200°C (especially with a sum of component (a) and alkylate of 35-45%) 25-40%> olefinic mixtures such as steam cracked spirit, 5-20% e.g. 7-15% reformate, 10-25% e.g. 12-20% toluene and 0.1-3% e.g. 0.5-2.0% butane. A preferred gasoline of the invention e.g. the last one usually RON 98-101, MON 86-89 E100°C (% evaporated at 100°C) 45-55 e.g. 48-52, aromatics 30-40% such as 30-35%, olefins 3-15% e.g. 5-10%, and total saturates of 50- 65%) e.g. 55-60%. Such a composition is free of added oxygenates. The toluene may be replaced by an equal volume of heavy reformate. A further gasoline composition of particular value comprises 0.5-5% e.g. 2-4% butane, 10-30% e.g. 15-25% full range alkylate (e.g. of FBP 175-200°C), 10-40% such as 20-35%) component (a), especially of alkylate cut 1 10-1 15, 115-125, 15-160, or 15- 100°C (in particular with the total of alkylate and component (a) of 35-60% e.g. 40- 55%, catalytic reformate 30-50%, and bisomer 5-15%, MON 87-90, RON 98-101 and ROAD 93-95. Such a composition is also free of oxygenate. Other motor fuel compositions of the invention may have different ranges of the Antiknock Index (also known as The ROAD Index), which is the average of MON and RON. For ROAD Indexes of 85.5-88.5, the compositions may comprise 8-30% component (a) e.g. 15-30%, and 10-50% e.g. 20-40% total component (b) mixture, 5- 30%, e.g. 5-20% total olefins and 10-40 e.g. 15-35% total aromatics, or 8-30% component (a), 10-50% total component (b) mixture, 5-40% total aromatic mixtures e.g. 20-30% and 10-60% e.g. 30-55% total olefinic mixtures. For ROAD Indexes of 88.5-91.0 the compositions may comprise 5-25% (or 5- 15%) component (a), 20-45% total component (b) mixture, 0-25% e.g. 1-10 or 10-25% total olefins, and 10-35% e.g. 10-20% or 20-35% total aromatics or 5-25% (5-15%) component (a), 20-45% total component (b) mixture, 0-35% total aromatic mixtures e.g. 1-15 or 15-35%, and 5-65% e.g. 5-30 or 30-65% total olefinic mixtures. For ROAD Indexes of 91.0-94.0 the fuel compositions of the invention may comprise 5-65% e.g. 5-20, 20-30, 30-65 or 40-65% component (a) and 5-40% (5-35%) e.g. 5-12 or 12-40% (12-30%) total component (b) mixture 1-30% e.g. 1-10 or 10-25% total olefins and 5-55% e.g. 5-15 or 15-35 or 35-55%o total aromatics, or the above amounts of component (a) with 0-55 e.g. 0.5-25% e.g. 10-25% or 25-55% of aromatic fractions and 0 or 10-60% e.g. 10-30% or 35-60% total olefin fractions. For ROAD values of 94-97.9, the fuel compositions may comprise 20-65% component (a) e.g. 40-65% component (a), 0-15% e.g. 5-15% total olefins, 0-20% e.g. 5-20% total aromatics and 5-50 e.g. 30-50% total component (b) mixture, or the above amounts of component (a) and total component (b) mixture with 0-30% e.g. 10-30% aromatic fractions and 0-30 e.g. 5-30% olefinic fraction, or the above amounts of component (a) e.g. 20-40% component (a), total component b mixture, total olefins and total aromatics, with 2-15% aromatic fractions and 18-35% olefinic fractions. Among preferred blends of the invention especially for the fifth to seventh aspects are unleaded blends comprising as component (a) at least 10% of at least one individual compound A or A 1 and component (b) as defined above, with the provisos that (i) when the compound A or A 1 is a trimethylpentane, then the blend contains 10-65% of total trimethyl pentanes, and at least 10% of an alkane of 6 or 7 carbons and MON value of at least 70 and RON value of at least 90, and preferably contains less than 5% of 2,2,3- trimethylpentane and 2,2,3-trimethyl butane, and (ii) when the compound A or A 1 is an alkane of 9 or 10 carbon atoms, then blend contains at least 10% of an alkane of 6 or 7 carbons of MON at least 70 and RON at least 90, and preferably contains less than 5% in total of 2,2,3-trimethyl pentane and 2,2,3-trimethyl butane. In the case of proviso(i) this blend preferably comprises at least 26% (or 30%) in total of alkanes of 7 or 8 carbons of MON at least 70 and RON at least 90, and/or contains less than 17% in total of aromatics. Preferred formulated unleaded gasolines of the invention comprise at least one gasoline additive and the preferred unleaded blend in the previous paragraph with the proviso (iii) when the compound A or A 1 is a trimethyl pentane, then the blend contains 10-65% of total trimethyl pentanes and less than 5% of 2,2,3-trimethyl pentane and 2,2,3-trimethyl butane, and (iv) when the compound A or A 1 is an alkane of 9 or 10 carbon atoms, the blend preferably contains less than 5% in total of 2,2,3-trimethyl pentane and 2,2,3-trimethyl butane. Preferred blends and gasolines of the invention especially in the fifth to seventh aspects can have MON values of 80-94 e.g. 80-85 or 90-94, RON values of 90-105 e.g. 90-95 or 97-105, ROAD values of 85-102, compound A or A 1 contents of 30-60% e.g. 40-60%> (comprising 1 or 2 compounds A or A 1 ), total naphtha contents of 35-65% (e.g. 35-55%) and l-5%> butane, the blends containing 1-8% e.g. 2-6% aromatics, 0-1% olefins and 91-99% (e.g. 94-98%) saturates. These are substantially aliphatic blends and gasolines of high octane numbers, without the use of oxygenates such as MTBE, and also substantially saturated. Other high octane blends and gasolines of the invention especially in the fifth to seventh aspects can have MON values of 80-95 e.g. 85-95, RON values of 90-100 e.g. 95-100, ROAD values of 85-97, compound A or A 1 contents of 30-60% e.g. 30-50% (comprising 1 or 2 compounds A or A 1 , medium naphtha contents of 5-30% and contents of total olefinic fraction such as steam cracked spirit of 30-50% and 1-5% butane, the blends containing 10-25% aromatics e.g. 12-18% aromatics, 4-14% olefins e.g. 6-12%), and 60-90% such as 70-80% saturates. These high octane materials are obtained without the use of oxygenates. Further blends and gasolines of the invention can have MON values of 84-90, RON values of 93-98, ROAD values of 86-94, and contain compound A or A 1 in amount of 15-35%, total naphtha of 40-65%> and olefinic fractions such as steam cracked spirit of 15-45% and 0 or 1-5% butane, with aromatic contents of 5-25% such as 10-18% olefin contents of 2-14% and saturate contents of 70-90%. Other blends and gasolines of the invention can contain 10-35% compound A or A 1 , and naphtha 30-50%, hydrocrackate 10-30% alkylate and/or isomerate 2-10%, and reformate 3-12%. The present invention also provides a blend comprising component (a) and usually at least one motor gasoline additive, e.g. as described above, in particular with the blend comprising not more than 5% in total e.g. less than 1% of hydrocarbon of bp more than 160°C, and preferably less than 5%, e.g. less than 4% of triptane or 223 trimethyl pentane. Examples of component (a) are described above, but it is preferably an alkylate cut, in particular a cut of 15-100°C. The invention can provide gasolines e.g. motor or aviation gasoline, in particular of 91, 95, 97, 98 RON values, with desired high Octane Levels but low emission values on combustion in particular of at least one of total hydrocarbons, NOx, carbon monoxide, and carbon dioxide, especially of both total hydrocarbons and carbon dioxide. Thus the invention also provides the use of a component (a) particularly a compound A or A 1 e.g. A3, 4, 6 or 9 or an alkylate cut of 15-160°C e.g. bpl5-100°C especially 15-60°C or 90- 106 in unleaded gasoline e.g. motor or aviation gasoline of MON at least 80 e.g. 80 to less than 98, e.g. as an additive to or component therein, to reduce the emission levels on combustion, especially of at least one of total hydrocarbons, NOx, carbon monoxide and carbon dioxide especially both of total hydrocarbons and carbon dioxide. The invention also provides a method of reducing emissions of exhaust gases in the combustion of unleaded gasoline e.g. motor or aviation gasoline fuels of MON of at least 80 which comprises having at least 10% component (a), in particular a compound A or A 1 e.g. A3, 4, 6 or 9 or an alkylate cut of bp 15-160°C or 15-100°C especially 15-60°C or 90- 106°C present in the fuel which is a gasoline of the invention. The invention also provides use of an unleaded gasoline of the invention in a spark ignition combustion engine to reduce emissions of exhaust gases. The compositions of the invention may be used in supercharged or turbocharged engines, or in normally aspirated ones. The component (a), preferably a compound A or an alkylate cut of bp 15-160°C or bp 15- 100°C especially 15-60°C or 90 to 106°C can reduce one or more of the above emission levels better than amounts of alkylate or a mixture of aromatics and oxygenate at similar Octane Number and usually decrease the fuel consumption as well. Automobile exhaust emissions vary very much depending on the vehicle technology and whether the engine is hot or cold, even with engines whose exhaust gases pass through a catalytic converter before reaching the outside environment. In a cold engine, the effects of friction, lubricants and the nature of fuel vapourisation among others, differ from those with a hot engine in an unpredictable way, and it is with cold engines that most tailpipe emissions are produced, because of enriched fuelling and, for those vehicles with catalytic converters, because the catalytic converter becomes increasingly effective at reducing emissions when it becomes hot. For the latter vehicles as well, a Lambda sensor upstream of the converter controls the fuel/air ratio entering the engine, but this is not effective with a cold engine (resulting in an unregulated fuel/air ratio). It is only after the cold start period that the sensor quickly becomes effective, (resulting in a regulated fuel air ratio), even when the catalyst is not yet hot enough to be effective. Thus cold start operations are different from hot running operations and yet contribute to a large amount of tailpipe emissions. The period of cold start relates to a period of time or distance, which may vary, depending on how the car is driven and/or ambient conditions e.g. up to 2 km or 4 or 2 min, or a temperature at which the engine coolant (e.g. radiator water temperature) is below 50°C. The car engine may also be deemed cold if it has not been operated for the previous 4hr before start, usually at least 6hr before start. Gasolines of the invention with component [a], especially one which is a stream obtained by or obtainable by distillation as a cut of B.Pt. 15-100C, give reduced emissions on cold start compared to base fuel. Thus the present invention also provides of method of reducing emissions of exhaust gases in the combustion of unleaded gasoline fuels of MON of at least 80 e.g. 80 to less than 98 from cold start of a spark ignition combustion engine, which comprises having a component[a] present in the fuel which is a gasoline of the invention. In the compositions, gasolines, methods and uses of the invention the component (a) is preferably used in an emission-reducing effective amount, in particular at cold start. The gasolines of the invention may be used in internal combustion spark ignition engines. They may be used to power moving vehicles on land and/or sea and/or in the air; the invention also provides a method of moving such vehicles by combustion of a gasoline of the invention. The vehicle usually has a driver and especially means to carry at least one passenger and/or freight. The engine sizes for motor gasoline use are usually at least 45cc e.g. 45-10000cc e.g. at least 200cc, such as 500-10000cc, in particular 950-2550, such as 950-1550, or 1250-1850cc, or 2500-10000cc such as 2500-5000 or 5000-9000cc. The engines have at least 1 cylinder, but preferably at least 2 or 3 cylinders, e.g. 3-16, especially 4-6 or 8 cylinders; each cylinder is usually of 45-1250cc e.g. 200-1200cc, in particular 240-520cc or 500-lOOOcc. The engines may be 2 stroke engines, but are preferably 4 stroke. Rotary engines e.g. of the Wankel type may be used. The motor engines may be used to power vehicles with at least 2 wheels e.g. 2-4 powered wheels, such as motor bicycles, tricycles, and 3 wheeled cars, vans and motor cars, in particular those vehicles legislated for use on a public highway but also off road e.g. 4 wheeled drive vehicles, sports cars for highway use, and racing cars, including drag racing cars and track racing cars. Power from the engine will preferably be connected to the driving wheels via a gearbox and clutch system, or other form of drive train system, to achieve the transition from a stationary to a mobile state. The engine and drive train will best allow a range of actual vehicle road speed of between l-350km/h, preferably between 5-130km/h and allow for continuous variation of speed thereof. The road speed of the vehicle is usually reduced by a braking mechanism fitted to the vehicle, the braking being generally applied by friction. The engine may either by air or water cooled, the air motion induced by a moving vehicle being used to directly, or indirectly cool the engine. The vehicle comprises a means to facilitate a change of vehicle direction, e.g. a steering wheel or stick. Usually at least 10% of the vehicle distance travelled is carried out at greater than 5km h. The engines using aviation gasoline are usually in piston driven aircraft, i.e. with at least one engine driving a means for mechanically moving air such as at least one propeller. Each engine usually drives at least one propeller driving shaft with 1 or 2 propellors. The aircraft may have 1-10 propellers e.g. 2-4. The aircraft engines usually have at least 2 cylinders, e.g. 2 to 28 cylinders, each of which is preferably greater than 700cc in volume, such as 700-2000cc e.g. 13 l Occ. The total engine size is usually 3700- 50000cc e.g. 3700 to 12000cc for single or twin engined passenger light aircraft, 12000 to 45000cc for 2 or 4 engined freight or airline use (e.g. 15-200 passengers, such as 50 to 150 passengers). The engines may have an engine power to weight ratio of at least 0.3Hp/lb wt of engine, e.g. 0.3-2Hp/lb, and may have a power to cylinder volume of at least 0.5 (Hp/cu.in) e.g. 0.5-2. Cylinders may be arranged in rows, V formation, H formation, flat ('horizontally opposed') or radially around a common propeller drive shaft. One or more rows/circles of cylinders may be used, e.g. flat 2, flat 4, flat 6, V12, 2 or 3 circles of 7 cylinders etc. Every cylinder has one and more preferably at least two spark plugs. A gear system may optionally be used to drive the propeller and or a supercharger. Alternatively, an exhaust turbo charger may also be present. Exhaust outlets may be individual or run into a common manifold and preferably point in the opposite direction to forward flight. Fins may be present on the exterior of the engine for air cooling. Greater than 90% of the distance travelled by the engine, when in use, is usually spent at 500 feet or more above ground level. Typically, during greater than 90% of the time when the engine is running, the engine operates at above lOOOrpm e.g. between 1000 to 3500 rpm. The aircraft usually has at least one tank having a capacity of at least 1001, especially with a total capacity of at least 10001. The gasolines of the invention may be made in a refinery by blending the ingredients to produce at least 200,0001/day of gasoline such as 1-lOmillion 1 day. The gasoline may be distributed to a plurality of retail outlets for motor gasoline, optionally via wholesale or bulk outlets e.g. holding tanks, such as ones of at least 2 million 1 capacity e.g. 5-15 million 1. The distribution may be by pipeline or in tanks transported by road, rail or water, the tanks being of at least 50001 capacity. At the retail sites e.g. filling station, the motor gasoline is dispensed to a plurality of users, i.e. the drivers of the vehicles, e.g. at a rate of at least 100 or 1000 different users per day. For aviation use, the gasoline is usually made in a refinery to produce at least 1000 barrels per day (or 100,0001/day) such as 0.1-2 million 1/day. The avgas is usually distributed by tanker by road, rail or water, or pipelines directly to the airport distribution or holding tanks, e.g. of at least 300,0001 capacity, from whence it is distributed by pipeline or tanker (e.g. a mobile refuelling bowser to fuel a plurality of aircraft, e.g. at least 5/day per tank; the aircraft may have one or more on-board tank each of at least 1001 capacity. The aviation gasolines of the invention comprising component (a) preferably have RVP of 38-49 kPa, 10-40% evaporated at 75°C, at least 50% evaporated at 105°C at least 90% evaporated at 135°C and the sum of temperature of 10% evaporated with that of 50% evaporation greater than 135°C. The present invention is illustrated in the following Examples. Example 1 An alkylate of IBP 31.9°C and FBP 191 3°C was a refinery grade product obtained commercially by HF catalysed reaction of refinery grade isobutene and isobutane. This alkylate was then distilled according to ASTMD2892 to give a series of cuts at the temperatures below in Table 1 with the analyses give in % w/w for their main components (present in at least 1% w/w). Table 1 Analyses A. Butane 9.1, isopentane 74.8, n-pentane 5.9, 2, 3 -Dimethyl butane 5.6, 2-Methyl pentane 1.8. B. Isopentane 12.9, n-Pentane 3.8, 2,3-dimethyl pentane 20.7, 2-methyl pentane 7.4, 3-methyl pentane 3.8, 2,4-dimethyl pentane 26.8, Benzene 1, 2,3-dimethyl pentane 12.2, isooctane 8.0. C. Isopentane 2.3, 2,3-dimethyl butane 10.4, 2-Methyl pentane 3.8, 3-Methyl pentane 2.1, 2,4-dimethyl pentane 23.4, 2,3-dimethyl pentane 20.4, isooctane 31.5. D. 2,3-dimethyl butane 3.5, 2-Methyl pentane 1.3, 2,4-dimethyl pentane 16.5, 2,3- dimethyl pentane 19.9, isooctane 51.5. E. 2,4-dimethyl pentane 7.2, 2,3-dimethyl pentane 14.3, isooctane 67.1, 2,5-dimethyl hexane 1.8, 2,4-dimethyl hexane 2.0, 2,3,4-trimethyl pentane 2.1, toluene 1.2, 2,3,3- trimethyl pentane 1.0. F. 2,4-dimethyl pentane 1.8, 2,3-dimethyl pentane 7.5, isooctane 68.2, 2,5-dimethyl hexane 4.1, 2,4-dimethyl hexane 4.7, 2,3,4-trimethyl pentane 6.0, toluene 1.4, 2,3,3- trimethyl pentane 3.1, high boilers 1.3 G. 2,3-dimethyl pentane 4.5, isooctane 57.8, 2,5-dimethyl hexane 6.0, 2,2,3-trimethyl pentane 1.3, 2,4-dimethyl hexane 7.0, 2,3,4-trimethyl pentane 1 1.4, toluene 1.3, 2,3,3- trimethyl pentane 6.3, higher boilers 3.0. H. 2,3-dimethyl pentane 1.3, isooctane 39.5, 2,5-dimethyl hexane 7.9, 2,2,3-trimethyl pentane 1.7, 2,4-dimethyl hexane 9.2, 2,3,4-trimethyl pentane 20.1, toluene 1.1, 2,3,3- trimethyl pentane 12.1, high boilers 6.9. Examples 2 and 3 A base Fuel was blended from 3.0 parts butane, 22.0 parts full range alkylate (as used as feed in Ex.1) 40 parts catalytic reformates 10 parts bisomer ,75 parts of this base fuel were blended with 25 parts of alkylate cut J to give blend Ex.2, and also separately with 25 parts of alkylate cut K to give blend Ex.3, and 25 parts of heavy reformate to give Comp. Blend. 3 Formulated gasolines were made, each containing one of the above blends and a 15mg/l of a phenolic antioxidant 55% minimum 2,4 dimethyl-6-tertiary butyl phenol 15%> minimum 4 methyl-2, 6-ditertiary-butyl phenol with the remainder as a mixture of monomethyl and dimethyl-tertiary butyl phenols. The gasolines of Ex.2 and 3 meet the European 2005 specification without use of oxygenates. In each case the gasolines were tested for MON and RON, and their Reid Vapour Pressure at 37.8°C. The results are shown in table 2, which also shows these properties for alkylate cuts A-M. The distillation properties of the blend Ex.2,3 and comp. Blend were tested according to ASTM D86 and shown in Table 3. Table 2 Table 3 Example 4 The emission characteristics on combustion of the formulated gasolines of comp. Blend, Ex.2 and 3, and the cuts A-N were compared. The fuels were tested in a single cylinder research engine at a speed/load of 50/14.3 rps/Nm with a LAMBDA setting of 1.01, and the ignition setting was optimized for the comparative blend. The emissions of CO, CO 2 , total hydrocarbons, Nox, were measured from the exhaust gases. The results were averaged. The results were as follows as shown in Table 4 expressed as the change in emissions compared to comp. Blend and in addition the percentage gravimetric change in the Fuel Consumption. Table 4 As the research engines were not fitted with catalysts in their exhausts, the reductions in emissions provide an indication of the benefits of reduced emissions downstream of the exhaust catalyst before any exhaust catalyst has heated up and became operable; this corresponds to cold start condition. Examples 5 and 6 Blends are made in the manner of Ex.2 and 3 from the base Fuel (75 parts) and cut A (25 parts) to give Ex.5 and separately with combined cuts B-E (25 parts) to give Ex.6. Formulated gasolines are made as in Ex.2 and 3. They give reduced emissions compared to the Comp. Blend. Example 7 A blend is made up with the following ingredients, steam cracked spirit 32.0%, full range alkylate (as the feed to Ex. l) 30%, cut A-E 10%, Reformate 11.0%, toluene 16.0%, butane 1.0%. A formulated gasoline also contains 15mg/l of the antioxidant of Ex.2/3. The properties of the fuel are as follows in Table 5 Table 5 This gasoline also gives reduced emissions. Examples 8-1 1 and Comparative Ex. A Various unleaded blends were made up with each of compounds A4, A6, A9, 225 trimethyl hexane in each case blended with various refinery streams as shown in Table 5, as well as Comp Ex. A with heavy reformate. 6 formulated gasolines were made, each containing one of the above blends " and 15mg/l of the phenolic antioxidant used in Ex.2-3. In each case the gasolines were tested for MON and RON, and their Reid Vapour Pressure at 37.8°C. The results are shown in table 5, which also shows their analyses and distillation profile (according to ASTM D86). The emission characteristics on combustion of the formulated gasolines of Ex. 8-11 and Comp. A were determined. The fuels were tested as in Ex. 4 in a single cylinder research engine at a speed/load of 20/7/2rps/Nm with LAMBDA setting of 1.01, and the ignition setting was optimised for the comparative blend A. The emissions of CO, CO 2 total carbon oxides, total hydrocarbons, No x were measured from the exhaust gases as was the Fuel Consumption (expressed in g/h'Whr). The results were averaged and compared to the comparative Ex. A. The degrees of change were as given in Table 6. Table 5 Figures denote % change relative to base (Fuel (Comp. A) ω co Examples 12-23 Blends were made up from the following ingredients, butane, full boiling range alkylate (as used in the feed in Ex. 1) catalytic reformate, light hydrocrackate full boiling range steam cracked spirit, naphtha, straight run gasoline full range catalytically cracked spirit and 2,2,4 trimethyl pentane. In addition most of the blends contained one or more alkylate cuts as described in Ex. 2 and 3. The analyses of the blends and their properties were as shown in Table 7. Table 7 The blends give reduced emissions on combustion. Table 7 (continued) The blends give reduced emissions on combustion. Examples 24-28 Blends were made up from the following ingredients, butane, full boiling range alkylate (as used in the feed in Ex. 1 ) catalytic reformate, full boiling range steam cracked spirit, naphtha. In addition the blends contained two or more alkylate cuts as described in Ex. 2 and 3. The analyses of the blends and the properties were as shown in Table 8. Table 8 The blends give reduced emissions on combustion.

Claims: Claims: 1. Use of component (a), which is a least one of (i) a substantially aliphatic hydrocarbon refinery stream of MON value of at least 85, at least 70% in total of said stream being branched chain alkanes, said stream being obtainable or obtained by distillation from a refinery material as a cut having Initial Boiling Point of at least 15°C and a Final Boiling Point of at most 160°C, said Boiling Points being measured according to ASTMD2892, and (ii) at least one branched chain alkane of MON value of at least 90 and boiling point in the range 15-160°C apart from 2,2,3-trimethylbutane and 2,2,3- trimethylpentane, in an unleaded gasoline of MON at least 80 to reduce the emission levels on combustion of said gasoline. 2. A method of reducing emissions of exhaust gases in the combustion of an unleaded motor gasoline fuel of MON at least 80 which comprises having present in said gasoline at least 10% of component (a) as defined in claim 1. 3. Use in a spark ignition combustion engine of an unleaded motor gasoline fuel of MON at least 80 which comprises at least 10% of component (a) as defined in claim 1 to reduce emissions of exhaust gases. 4. Use or method according to any one of claims 1-3 wherein the gasoline is an unleaded motor gasoline. 5. Use or method according to any one of claims 1-3 wherein the gasoline is an unleaded aviation gasoline- 6. Use or method according to any one of claims 1-5 wherein the gasoline comprises a composition having a Motor Octane Number (MON) of at least 80 comprising at least 2% (by volume of the total composition) of said component (a)(i) which is a cut from an alkylation product, and as component (g) at least 5%> of at least one paraffin, aromatic hydrocarbon compound or olefinic hydrocarbon of bp60-160°C, with not more than 5% of the total composition of hydrocarbon of bp more than 160°C, and less than 5% of 2,2,3-trimethylbutane or 223 trimethyl pentane. 7. Use or method according to claim 6 wherein the component (a) is a stream which is a alkylate cut of Boiling Point of 60-140°C, especially 60-100°C, or 90-106°C. 8. Use or method according to any one of the preceding claims wherein the gasoline comprises 20-55% preferably 20-35% of said component (a). 9. Use or method according to any one of the claims 1-5 wherein said branched chain hydrocarbon has 4-12 carbon atoms. 10. Use or method according to claim 9 wherein said branched chain hydrocarbon has 4-8 carbon atoms and boiling point 15-100°C and is present in at least 5% in said composition. 11. Use or method according to claim 9 wherein said gasoline comprises at least 15% by volume of said branched chain hydrocarbon which has 8-12 carbons. 12. Use or method according to any one of claims 1-5 and 9-1 1 wherein said branched chain hydrocarbon has an alkane chain of carbon atoms with two methyl groups on carbon atom 2 in the chain. 13. Use or method according to claim 12 wherein said hydrocarbon is isooctane. 14. Use or method according to any one of claims 9 or 1 1-13 wherein said gasoline comprises at least 15% by volume of at least one branched chain hydrocarbon, which has 8-12 carbons and 3 methyl or ethyl branches, and there being a minimum of at least 10% by volume of at least one of such individual branched chain hydrocarbons. 15. Use or method according to claim 14, wherein said branched chain hydrocarbon has 8-10 carbons. 16. Use or method according to claim 15 wherein said hydrocarbon is isooctane. 17. Use or method according to claim 15 wherein said hydrocarbon is not 2,2,4- trimethylpentane. 18. Use or method according to any one of claims 9-17 wherein said gasoline comprises a blend composition with a MON value of at least 81 and RON value of at least 91 and also comprises at least one component (g), which is at least one liquid hydrocarbon or mixture thereof of bp60-160°C having a MON value of at least 70 and Ron value of at least 90, the total amount of component (g) being at least 20%. 19. Use or method according to any one of claims 9-17 wherein said gasoline comprises a composition of MON value at least 81 and RON value of at least 91 which also comprises at least one component (g) which is at least 20% in total of one or more refinery streams, such that said blend composition contains in total at least 70%> of saturated hydrocarbons. 20. Use or method as claimed in any one of the preceding claims wherein the gasoline or blend composition has RON value of at least 97 e.g. 97- 101. MON value of 85-90 such as at least 86, aromatics content of less than 35%, olefins content of less than 14%, benzene less than 1%, % evaporated at 70°C 10-50% e.g. 10-45%, % evaporated at 100°C at least 46% such as 46-60%, % evaporated at 150°C 70-97% e.g. at least 88% and RVP of 60 kPa or less e.g. 40-60 kPa 21. A formulated unleaded gasoline which comprises at least one motor or aviation gasoline additive, and at least one of an unleaded gasoline of MON at least 80 and a blend composition, each as defined in any one of claims 1-20. 22. An unleaded gasoline according to claim 21 in which when the branched chain hydrocarbon is a trimethyl pentane, then the blend composition contains 10-65% of total trimethyl pentanes. 23. A gasoline according to claim 21 or 22 which is a motor gasoline. 24. An unleaded composition having a Motor Octane Number (MON) of at least 80 comprising at least 2% (by volume of the total composition) of component (a), which is a substantially aliphatic hydrocarbon refinery stream, of MON value of at least 85, at least 70% in total of said stream being branched chain alkanes, said stream being obtainable or obtained by distillation from a refinery material as a cut having Initial Boiling Point of at least 15°C and Final Boiling Point of at most 160°C, said Boiling Points being measured according to ASTMD2892, and as component (g) at least 5% of at least one paraffin, aromatic hydrocarbon compound or olefinic hydrocarbon of bp60- 160°C, with not more than 5% of the total composition of hydrocarbon of bp more than 160°C, and less than 5% 2,2,3-trimethylbutane or 2,2,3-trimethylpentane. 25. An unleaded composition having a Motor Octane Number (MON) of at least 80 comprising at least 5%> (by volume of the total composition) of component (a), which is at least one branched chain alkane of MON value of at least 90 and of boiling point in the range 15-160°C and as component (g) at least 5% of at least one paraffin, aromatic hydrocarbon compound or olefinic hydrocarbon of bp60-160°C, with not more than 5% of the total composition of hydrocarbon of bp more than 160°C, and less than 5% of 2,2,3 -trimethylbutane or 2,2,3-trimethylpentane. 26. An unleaded blend composition having a Motor Octane Number (MON) of at least 81 and Research Octane Number (RON) of at least 91 which comprises component (a) a total of at least 15% by volume of the blend composition of at least one branched chain hydrocarbon, which is an alkane of 8-12 carbon atoms with methyl or ethyl branches (hereinafter called a compound (A)) there being a minimum of at least 10% by volume (of the blend composition), of at least one individual compound (A), and component (g) at least one liquid hydrocarbon or mixture thereof of bp60-160°C having a MON value of at least 70 and RON value of at least 90, the total amount of component (g) being at least 20%, with the proviso that the blend composition contains less than 5% of 223 trimethyl pentane, and less than 1% in total of 2,2,3-trimethylbutane and 2,2,3- trimethylpentane. 27. A blend composition according to claim 24 or 25 comprising as component (a) at least 10% of at least one individual compound of said branched chain hydrocarbons and component (g) as defined in claim 25 or 26, with the provisos that (i) when the said branched chain hydrocarbon is a trimethylpentane, then the blend contains 10-65% of total trimethyl pentanes, and at least 10% of an alkane of 6 or 7 carbons and MON value of at least 70 and RON value of at least 90, and (ii) when the said branched chain hydrocarbon is an alkane of 9 or 10 carbon atoms, then blend contains at least 10% of an alkane of 6 or 7 carbons of MON at least 70 and RON at least 90. 28. An unleaded blend composition of MON value of at least 81 and RON value of at least 91 which comprises component (a) as defined in claim 25 and as component (b) at least 20% in total of one or more refinery streams, such that the blend composition contains in total at least 70% of saturated hydrocarbons. 29. A process for preparing at least 2 clean compositions suitable for production of gasolines, which comprise fractionating an alkylation product to produce a first cut boiling in at least part of the range 90-106°C, and a second cut boiling at temperature lower than said first cut and a third cut boiling at a temperature above said first cut, blending said first cut as component (a) with component (g) to produce a first high octane unleaded gasoline composition of RON at least 97 and MON value at least 86 with low emissions of combustion, said components (a) and (g) and composition being as defined in any of claims 6-8, 18-20, 24-28 and incorporating said second and third cuts as component (a) with said component (g) to produce at least one second high octane unleaded gasoline composition of RON at least 92 and MON value at least 80 with low emissions on combustion. 30. A process according to claim 29 wherein said compositions and gasolines are substantially free of oxygenates

Inventors: CLARK ALISDAIR QUENTIN, HOWARD PHILIP, PARKER ANTHONY GEORGE WILLIAM, CLARK, ALISDAIR, QUENTIN, HOWARD, PHILIP, PARKER, ANTHONY, GEORGE, WILLIAM
Applicants: BP OIL INT, CLARK ALISDAIR QUENTIN, HOWARD PHILIP, PARKER ANTHONY GEORGE WILLIAM, BP OIL INTERNATIONAL LIMITED, CLARK, ALISDAIR, QUENTIN, HOWARD, PHILIP, PARKER, ANTHONY, GEORGE, WILLIAM
Application year: 2000
Main classification: C10L1
IPC codes: C10L1