Patent GB-577747-A (GB)
Title: Process for the preparation of aviation fuels from gaseous hydrocarbons
IPC: C10L1/06
Filed: 1943-02-09
Abstract: <PICT:0577747/IV/1> Butenes in a C4 cut are copolymerized with hot sulphuric acid as catalyst to form i-octenes boiling mainly above 225 DEG  F., the hydrocarbon product is hydrogenated and fractionated to separate the liquid isoparaffinic product from the C4 paraffins, the latter used to alkylate olefins in a C2-C3 cut with a boron fluoride-water catalyst producing an alkylate boiling mainly above 130 DEG  F., and said alkylate is combined with said liquid isoparaffinic product to give an aviation fuel.  The C4 cut is treated at about 125-250, preferably 160-175 DEG  F. while in liquid phase at 150-450 lbs./sq. in. with 50-75, preferably 60-70 per cent acid for about 2-30, preferably 10-20 mins.  Hydrogenation is effected at about 200-650 DEG  F. and 200-3000 lbs./sq. in. for 10-60 mins. or more using metal, metal oxide or metal sulphide catalysts alone or on carriers.  The alkylation is preferably performed with an olefinic fraction wherein the ratio of ethylene to propylene is at least 1.5 : 1 and preferably 4 : 1 or more. The isobutane to olefin ratio should be at least 2 : 1 and preferably 3 : 1 or higher.  The catalyst preferably contains at least 70 per cent BF3 and the ratio of catalyst to hydrocarbon is about 1 : 1 or 1 : 2.  Temperature is about 60-80 DEG  F. and pressure 100-250 lbs./sq. in. to maintain liquid phase.  Refinery gases containing C2 to C4 olefins and paraffins are fed by line 1 to a fractionator 2 where a C4 cut is separated and fed through heater 5 to polymerizer 6. C2 to C3 cuts are led off by lines 7, 71 through cooler 10 to alkylator 11.  To reduce the C3 content, part of the stream 71 may be eliminated. Lighter gases are expelled through line 13 and may be fed by lines 14, 15, together with natural or refinery gas from line 18, to a heater 16 for cracking or for heating with subsequent cracking or dehydrogenating in a catalytic reactor 17 containing, e.g., active alumina or silica, clays or metal oxides.  The products pass by cooler 21 to fractionator 2.  Hydrocarbons above C4 leave as bottoms. The C4 cut is converted into i-octenes in polymerizer 6, acid is separated in 27 for recycling, and the hydrocarbons washed, heated and hydrogenated in reactor 39. Hydrogen is separated in 43 and the hydrocarbons fractionated in tower 46 to obtain a 225-245 DEG  F. fraction from line 54 and a 200-225 DEG  F. fraction from line 55. Uncondensed gases, mainly butanes, pass through reflux analyser 50 and by line 52 to mix with the C2 to C3 cut passing to alkylator 11. Catalyst is introduced at 56 and recycled by line 57.  Under the conditions specified, an alkylate having a substantial 130-138 DEG F. fraction is formed.  The alkylate is separated in fractionator 69 into a 130-138 DEG  F. cut withdrawn through line 72 for combining with the hydrogenated polymer fraction from line 54, a butane cut from line 78 which may be isomerized, unconverted C2 to C3 hydrocarbons which may be recycled by lines 74, 75, and heavy bottoms.  Other fractions may be separated in fractionators 46 and 69 for use in motor fuels.  In an example, a hydrogenated polymer fraction boiling at 225-245 DEG  F. is combined with an alkylate cut boiling at 130-138 DEG  F. in ratios of 80 : 20, 70 : 30 and 50 : 50 per cent by volume to give aviation spirit which may be blended with T.E.L.