PROCESS FOR THE PRODUCTION OF ALKYL AROMATIC HYDROCARBONS

Abstract: A process for the production of gasoline from a C4-fuel gas containing ethene and propene and catalytic reformate containing C6 to C8 aromatic hydrocarbons. The C4-fuel gas in stream (28) is obtained by catalytic cracking of the vacuum gas oil fraction (7) obtained by distillation of a crude feed (1) in a distillation apparatus (2). The reformate C6-C8 aromatic hydrocarbons in stream (15) is obtained by hydrotreating naphta (5) in zone (9), followed by reforming in zone (13). The C4-fuel gas (28) and C6-C8 aromatic reformate (15) are mixed and contacted in a catalytic reactor (29) with a zeolite catalyst to convert ethene and propene in the fuel gas to C5+ aliphatic and aromatic hydrocarbon gasoline and to convert C6 to C8 aromatics in the reformate into C7 to C11 hydrocarbon gasoline. In a preferred embodiment, the process comprises maintaining a fluidized bed of zeolite catalyst particles in a turbulent reactor be at a temperature of 350-900 DEG C and a pressure of 20-650 psig (240-4580 kpa). The weight ratio or aromatics to olefins is at least 5:1.

Description: FROCESS FOR THE 3?RODCCTION OF AIKY ARCMA IC HYraPCRRBONS The present Invention relates to a process for the production of alkyl arαnatic hydrocarbons suitable as gasoline blending stock. The fluid catalytic cracking of hydrocarbons in modern refinery operations produces large amounts of C.- fuel gas ∞ritaining light olefins of essentially no gasoline product value. In addition, the catalytic refo__ming of hydrocarbons produces large amounts of C g to C_ arαnatic hydrocarbons which, thcug having value as gasoline blending stock, are produced in excessive amounts. The present invention provides a catalytic process for a2_kylating C g to C g arαnatics contained in reformate with li t olefins contained in C.- fuel gas.to form alkyl arαnatic hydrocarbons useful as gasoline blending stock. Chen US Patent No. 3,729,409 discloses a process for iπjaxiving the yield-octane number of a reformate by contacting the refαπnate in the presence of hydrogen with a zeolite catalyst. Garwood et al US Patent No. 4,150,062 discloses a process for the conversion of c_ to C. olefins to gasoline vzhich. comprises oantacting the olefins with water in the presence of a zeolite catalyst. US Patent Nos 4,016,218 and 3,751,506 disclose processes for the alkylatiαn of benzene with olefins over ZSM-5. US Patent No. 4,209,383 discloses the catalytic alkylatiαn of benzene in reformate with C--C. olefins to produce gasoline. The present invention resides in a process for producing an alkyl arαnatic product, useful inter alia as a gasoline blending stock, cαrprising contacting a feed stream ccmprising C.- olefins with a feed stream ccπprlsing C g to C g arαnatic hydrocarbons at an arαnatic to olefin weight ratio of at least 5:1 in the presence of a fluidized zeolite catalyst in a riser reactor having multiple olefin feed injection points to alkylate the C g to C- aranatics with the olefins to produce the required alkyl arαnatic product. The process of the present invention, because of the use of multiple olefin feed injection points in the riser reactor, maintains a high weight ratio of arαnatics to olefins during the reaction and obtains a maximum conversion of light olefins and arαnatics to alky! arαnatics. The high weight ratio of arαnatics to light olefins in the riser reactor also m__n__mizes olefin oligαnerizatiαn reactions and reduces coke formation. The present invention allows conventional petroleum refining steps inclu ing fracticnation, hydrotreating, catalytic reforming and fluidized catalytic cracking to be combined with a novel zeolite-catalysed process utilizing a riser reactor to upgrade the fuel gas and reformate process streams. A gasoline boiling range alkyl arαnatic hydrocarbon product is thereby produced frαn the fuel gas stream frαn the fluidized catalytic cracking process step and the reformate stream from the catalytic reforming step. Typically, when the process of the present invention is employed in a conventional oil refinery, the crude oil feed is initially subjected to distillation to separate several hydrocarbon streams including a light gas, a gasoline boiling range light distillate naphtha, a middle distillate, a vacuum gas oil and a bottαns or reduced crude stream. The naphtha .stream is hydrσtreated to remove sulfur and nitrogen cαrpounds and then fed to a catalytic reforming zone wherein the octane value of the naphtha stream is increased, the αxiσeπtraticn of arαnatic hydrocarbons is increased and hydrogen is produced as a by-product. The middle distillate stream is also hydrσtreated to produce products such as kerosene and jet fuel. The vacuum gas oil is fed to a fluidized catalytic cracking (FCC) zone in which there is produced a light gasoline boiling range distillate, a fuel gas containing C. to C. olefins and paraffins and a heavy distillate. The FCT unit includes a fluidized bed molecular sieve catalytic cracker and a catalyst regenerator. The molecular sieve catalyst is αantinuously regenerated in the regenerator by oxidatively renewing coke deposits frαn the catalyst by burning with air regeneration gas. The reduced crude may be fed into a subatmospheric pressure or vacuum fractiαning column. The reduced crude may also be subjected to processing steps such as propane deasphalting and hydrrocracking. In accordance with the present invention, the catalytic reformate containing Cg to Cg arαnatic hydrocarbons and the PCC fuel gas stream containing C χ to C 4 olefins and paraffins are fed to a fluidized zeolite catalyst reaction zone in a riser reactor. The riser reactor cxsitaining the zeolite catalyst is operated under conditions such that the weight ratio of arαnatics to olefins is at least 5:1, preferably 10:1 to 15:1, whereby the C.- olefins, e.g. ethene and propene, in the fuel gas feed stream alkylate the C g to C g arαnatic hydrocarbons, particularly benzene, in the reformate feed stream to for C, to C^ alkyl arαnatic hydrocarbons such as toluene, xylene, ethyl benzene, methyl ethyl benzene, diethyl benzene, prcpyl benzene and methyl prcpyl benzene. The catalyst in the riser reactor is continuously or intermittently withdrawn and regenerated in a catalyst regeneration zone. The catalyst can be regenerated by contact with a hydrogen containing regeneration gas or with an oxygen containing regeneration gas. Prior to carrying out the regeneration step the catalyst can be contacted in a stripping zone with an inert stripping gas such as nitrogen or steam to remove hydrocarbons absorbed on the catalyst. 11266 -4- The effluent hydrocarbon stream from the riser reactor is passed into a separator in which a light hydrocarbon overhead stream, e.g. C.- hydrocarbons, is withdrawn and fed to an absorber in which a major portion of the C_+ hydrocarbons are absorbed and removed. The remaining C - hydrocarbons are taken overhead and can be recycled to the zeolite catalyst reaction zone. The bσtαns ftαn the separator contain ς.+ hydrocarbons including the C_ to C . alkyl arαnatic hydrocarbons and are fed to a debutanizer from which an overhead C.- gas stream is removed. The debutanized gasoline product is removed as a bottoms product and is fed to the gasoline product pool. The zeolite alkylatiαn catalyst used in the riser reactor is preferably a medium pore shape-selective crystalline aliirninosilicate zeolite having a sHira-to-alumina ratio of at least 12, a constraint index of 1 to 12 and acid c_racking activity of 1-200. In an operating reactor, the coked catalyst may have an apparent activity (alpha value) of 1 to 80 under the process conditions to achieve the required degree of reaction severity. Representative of the preferred zeolites are ZStf-5, ZSM-11, ZSM-12, ZSZ*-22, ZSM-23 and ZSM-35. ZSM-5 is the most preferred zeolite and is disclosed in US Patent No. 3,702,886 and US Patent Reissue No. 29,948. Other suitable zeolites are disclosed in U. S. Patents 3,709,979; 3,832,449; 4,076,979; 4,076,842; 4,016,245 and 4,046,839; 4,414,423; 4,417,086; 4,517,396 and 4,542,251. While suitable zeolites having a s__Hσa-to-alι_mina molar ratio of 20:1 to 200:1 or higher may be used, it is advantageous to eπplqy ZSM-5 having a si_Uca-to-alu_rdna molar ratio of 25:1 to 70:1. m practice, the zeolite will normally be bound with 5 to 95% of a suitable i_∞rganic oxide binder. A preferred catalyst ccπprises 25% to 65% HZSM-5 catalyst contained within a s_llica-alιmιina matrix binder. Typically, in order to allow the catalyst to be maintained in the required fluidized condition, 1266 -5- the bound catalyst has a particle size of 1-150 microns, with the average particle size being 20-100 microns, or more preferably 40-80 microns. The preferred light olefin gas feedstock contains C to c. alkenes (mono-olefins), wherein the total C--C. alkenes are in the range of 10 to 40 wt %. Non-deleterious components, such as methane, C_ to C. paraffins and inert gases, may be present. S ne of the paraffns will be converted to C.+ hydrocarbons depending an the reaction conditions and catalyst employed. A particularly useful feedstock is a light gas by-product of P0C gas oil cracking units containing 10-40 mol % C--C olefins and 5-35 mol % a, with varying amounts of C χ to C 3 paraffins and inert gas, such as N 2 . The feedstock can contain primarily ethene, propene and or butene. -me l± t olefin feed gas is described in more detail in the Table 1 below. Tfrttle Weiαht% Broad Intermediate Preferred 0-10 1-10 1-4 Shene 1-99 8-50 8-35 Propene 0-99 3-50 3-40 Ifchene/Ercpene 1-99 5-80 5-60 The catalytic reformate feedstock contains C- to C Q arαnatic hydrocarbons and C_ to C_ paraffinic hydrocarbons. The Cg to C g arαnatic hydrocarbons include benzene, toluene, xylene and ethyl benzene. All or part of the ς. to C g paraffinic hydrocarbons may be removed frαn the reformate stream prior to reacting the reformate with the light olefins. The catalytic reformate feedstock is described in more detail below Table 2. -6- Table 2 Broad intermediate Preferred Specific Gravity 0.72-0. 88 0.76-0.88 0.76-0.83 Boiling Range, "F 60-400 80-400 120-320 • C 16-204 27-204 49-160 Weiφt% Broad Intermediate Preferred Benzene 1.0-99 2-60 10-40 Toluene ... 2.0-60 10-40 10-35 C 8 Arαnatic {±} 0-60 0-50 0-8 Cg-C 8 Arαnatics 5-100 10-95 35-75 (l) Xylene and ethyl benzene ccπpαneπt. The ethene and propene in the light olefin feed are converted to alkyl arαnatics in can amount of 80 to 100, preferably 90 to 100 and mate preferably 95 to 100 wt.% of the olefin feed. The Cg to C_ aromatics in the catalytic reformate feed, including benzene, toluene and C_ arαnatics, are converted to al_kyl arαnatics in an amount of 5 to 80 and preferably 20 to 50 wt.% of the feed. Dhreaσted arαnatic feed can be recycled to the riser reactor. As previously stated, the process of the present invention is carried out in a riser reactor having multiple olefin feed injection points in the riser section of the reactor. The reaction between the arαnatic hydrocarbons and the light olefins occurs primarily in the riser section of the reactor, although sane conversion can take place in an upper fluidized bed section of the reactor. The reaction temperature in the riser section of the reactor is 350 to 900'F (177 to 482*C), preferably 500 to 800 β F (260 to 427'C) and more preferably 600 to 750 β F (315 to 399 β C). The reaction pressure in the riser section of the reactor is 20 to 650 psig (240 to 4580 kPa), preferably 120 to 420 psig (930 to 3000 KPa) and more preferably 150 to 250 psig (1140 to 1830 kPa). The weight ratio of catalyst to reformate feed can be 0.5:1 to 50:1, preferably 1:1 to 10:1 and more preferably 3:1 to 11266 -7- 7:1. The weight ratio of arαnatic hydrocarbon to olefin hydrocarbon throughout the reaction is at least 5:1, typically 7:1 to 20:1, preferably 10:1 to 20:1 and more preferably 12:1 to 15:1. The transfer gas velocity in the riser transfer regime section of the reactor is typically 5 to 100 ft sec (1.5 to 30 τa/sec), preferably 5 to 30 ft/sec (1.5 to 9.1 π^sec) and more preferably 10 to 20 ft sec (3 to 6.1 τa/sec) . The use of an upper fluidized bed is an alternative embodiment of the invention. The riser reactor can be used without an upper fluidized bed. The fluidizing gas velocity in the upper fluid bed section of the reactor, when the upper fluidized bed is used, is 0.3 to 4 ft/sec (0.1 to 1.2 msec), preferably 1 to 3 ft sec (0.3 to 0.9 msec) and more preferably 1 to 1.5 ft sec (0.3 to 0.5 ■ a sec). The upper fluid bed section of the reactor is preferably operated as a turbulent regime fluidized bed. The hydrocarbon feed and catalyst contact time in the riser section of the reactor is typically 1 to 20 seconds and preferably 3 to 10 seconds. The riser section of the reactor can be 10 to 100 ft (3 to 30 m), typically 20 to 60 ft (6 to 18 m) in height. The diameter of the riser section can be 0.1 to 1 ft (0.03 to 0.3 m), typically 0.1 to 0.5 ft (0.03 to 0.15m). There can be 2 to 8, e.g.2 to 6, typically 2 to 4 olefin feed injection points along the height of the riser reactor. This number of feed injection points includes the feed injection point at the bottαn of the riser reactor. The multiple feed injection points are spaced 5 to 25 ft (1.5 to 7.6 m), typically 5 to 15 ft (1.5 to 4.6 m) apart, along the height of the reactor, preferably along the height of the riser section, with the first one in the bσttαn of the reactor. 11266 -8- An olefin feed injection point can, however, be provided in the upper fluidized catalyst bed section of the reactor, and would be included in the above numbered olefin feed injection points. The multiple olefin feed injection maintains the desired high arαnatic to olefin ratios in the reaction zone during the reaction. The olefin feed can be substantially uniformly distributed through the multiple feed points so as to maintain in the riser reactor a weight ratio of arαnatics to olefins in the riser section of the reactor and or in the upper fluidized catalyst bed section of 7:1 to 20:1, preferably 10:1 to 15:1. The fluidized bed section of the riser reactor, when used, can be 5 to 30 ft (1.5 to 9.1 m), typically 5 to 20 ft (1.5 to 6 m) in height. The fluidized bed diameter can be 1 to 30 ft (0.3 to 9.1 m), typically 2 to 6 ft (0.6 to 1.8 ). Catalyst particles are disengaged frαn the hydrocarbon gas product in a top dilute pha.se of the reaction zone in one or more internal gas solid separation cyclones or in an external sintered metal filter. All or at least a portion of the separated catalyst is returned to the riser reactor. The alkyl arαnatic hydrocarbon product gas is removed from the top of the reactor at a teπperature of 400 to 800'F (204 to 427*C), preferably 600 to 750*F (315 to 399'C) and more preferably 650 to 750 β F (343 to 399*C) and taken for further processing. The α_tϊt_acting of the light olefin gas feed with the catalytic reformate feed over the zeolite catalyst in accordance with the present invention produces the follcwing products. The ethene and propene cαtpαnents of the light olefin gas feed react with and alkylate the co, to Co. arαnatics in the catalytic reformate feed to produce primarily G_ to C.. alkyl arαnatic hydrocarbons which may themselves rearrange and transalkylate over the zeolite catalyst. /11266 -9- The C to C.. alkyl arαnatic hydrocarbon product obtained includes C χ to C 4 lower alkyl substituted arαnatic hydrocarbons such as methyl, ethyl, prcpyl and butyl benzene cαtpcunds. The CL to C-. alkyl arαnatic hydrocarbon product may contain one or more of the foregoing lower alkyl sutetituents, providing however that the total number of carbon atoms in the substituents does not exceed 5. Typical C_ to C.. arαnatic hydrocarbons, i. e. alkyl aromatic hydrocarbons, include toluene, ethyl benzene, xylene methyl ethyl benzene, prcpyl benzene, trimethyl benzene methyl prcpyl benzene, butyl benzene, tetramethyl benzene, methyl butyl benzene and diethyl benzene. The G- to G j - alkyl arαnatic hydrocarbons have a higher octane value than the starting materials and enrich the overall octane quality of the gasoline blending stock. The alkylatiαn reaction converts a small portion of the light olefin feed to undesirable coke by-product primarily due to olefin oligαnerizatiαn reactions which coke deposits on the catalyst and as the coke builds up partially deactivates the catalyst. The partially deactivated catalyst containing deposited coke and absorbed hydrocarbons can be regenerated by contacting the catalyst in a catalyst regeneration zone with a hydrogen ∞πtaining gas or by contacting the catalyst with an oxygen containing gas. Hi order to regenerate the catalyst and to recover the absorbed hydrocarbon product contained in the catalyst pores and voids, a portion of the partially deactivated catalyst σσπta__ning the deposited coke and absorbed hydrocarbon product is continuously or intermittently withdrawn frαn the upper portion of the riser reactor or from the fluidized bed (when used) and transferred to a catalyst regeneration zone. The catalytic coke make is typically 0.005 to 1 wt.%, e.g. 0.005 to 0.3 wt.% and more typically 0.005 to 0.1 wt.% of the olefin feed. In accordance with an embod_Lmeπt of the present iπveπtiαn the coke make is within the range of 0.001 to 0.025, for example 0.001 to 0.02 wt.% based on olefin feed. To effect hydrogen regeneration, the partially deactivated catalyst is contacted in a catalyst regenerator with hydrogen gas from the catalytic reformer. 4 to 800 %hr, preferably 10 to 200%hr and more preferably 12 to 170%hr of the catalyst inventory in the riser reactor is withdrawn for regeneration. The hydrogen gas is fed into the bottom of the regenerator at a sufficient rate to maintain the catalyst as a fluidized bed. The catalyst regeneration zone temperature is maintained at 450 to 1400 β F (232 to 760'C), preferably 700 to 1200 β F (371 to 649*C) airf more preferably 700 to 1000 β F (371 to 538*C). The catalyst regeneration zone pressure is generally maintained at about the same operating pressure as the riser reactor. The regenerator, however, can be operated at lower pressures, for example, at about ambient pressure. The catalyst residence time in the regenerator is 0.1 to 1 hr and typically 0.5 to 1 hr. In order to effect oxygen regeneration, a portion of the partially deactivated catalyst containing absorbed hydrocarbon product in the catalyst pores is continuously or intermittently withdrawn frαn the upper fluidized portion of the riser reactor, e.g. frαn the fluidized bed, if used, and transferred to a stripping zone in which the absorbed hydrocarbons are stripped with an inert gas. The stripped catalyst is then transferred to a catalyst regeneration zone in which the deposited coke is oαάdatively removed by combustion of the coke with an oxygen cxsitaining gas such as air. Typically, 1 to 400%/hr, preferably 5 to 200 %/hr and more preferably 10 to 150 %/hr of the catalyst inventory in the riser reactor is withdrawn for stripping and regeneration. The partially deactivated catalyst is transferred to the stripper vessel and is maintained in the stripper vessel as a fluidized bed at a tetπperature of 10 to 200'F (5 to 110 β C) less than the temperature in the riser reactor. The stripper vessel is maintained at a pressure within in abcut plus or minus 20 psi (140 Pa) of the pressure in the regenerator. The catalyst is maintained as a fluidized bed by the introduction of an inert stripping gas such as nitrogen or steam at a sufficient rate to fluidize the bed. The partially deactivated catalyst in the stripping zone is stripped of substantially all of the alkyl arαnatic product, which is recovered, leaving on the catalyst substantially only the deposited coke. The stripped catalyst is withdrawn frαn the .stripping zone and is transferred to the catalyst regeneration zone in which the catalyst is maintained in a fluidized bed. The partially deactivated catalyst is contacted in the fluidized bed with an oxygen α_ntain__ng regeneration gas, such as air, to effect combustion of the coke deposited on the catalyst and removal of the coke frαn the catalyst and regeneration of the catalyst. The preferred regeneration gas is air which contains about 21% oxygen, because of its ready availability and low cost. A readily available refinery source of air regeneration gas is from the air regeneration gas feed to the FCC catalyst regenerator unit. A sufficient excess amount of the oxygen containing regenerating gas is fed to the bottom of the regenerator through a distribution plate to the regeneration zone to maintain a temperature in the regeneration zone of 700 to 1000'F (371 to 538 β C), preferably 700 to 950 β F (371 to 510*C), and more preferably 800 to 900 β F (427 to 482°C) and to provide sufficient fluidizing gas to maintain the catalyst in a fluidized condition. Cooling coils may be used in the regenerator to help control the regeneration teπperature. The regeneration zone can be operated at a higher or lower pressure than the riser reactor. The pressure in the regenerator is maintained at 30 to 450 psig (310 to 3200 pKa), for example, 30 to 200 psig (310 to 1480 pKa) and typically at about the pressure of riser reactor. The catalyst particles are disengaged frαn the fluidizing gas, including the cxπbustion products of the coke and oxidizing gas, in the top dilute phase of the regeneration zone by one ormore gas-solid separation cyclones and the separated catalyst is returned to the regenerator. The excess oxygen in the regenerating gas and the cαπbusticn products including carbon dioxide and water are removed frαn the regenerator as effluent gases.The effluent gases are conveniently fed to the PCC catalyst regenerator unit in whic the excess oxygen is burned. The regenerated catalyst contains only a small residual amount of carbon in the amount of 0.001 to 0.2 wt%, preferably 0.01 to 0.1 wt% and more preferably 0.01 to 0.05 wt% based on the weight of catalyst and is withdrawn frαn the regeneration zone and introduced to the reaction zone and contacted with fresh arαnatic and olefin feed. The invention will now be more particularly described with reference to the aσoαipaπying drawings, in which: Figure 1 is a flow diagram of part of an oil refinery iiTCorporating an alkylatiαn process according the present invention, Figure 2 is a schematic representation of apparatus for performing an alkylatiαn process according to one example of the invention, and Figure 3 is a schematic representation of apparatus for performing an alkylatiαn process according to a further example of the invention. Referring to Figure 1, in the refinery shown a crude oil feed is fed through line 1 to a crude oil distillation unit 2 and is separated into fractions having different boiling point ranges. The C. to C. light hydrocarbons and any gases dissolved in the feed are removed overhead through line 3 and passed to a gas recovery zone (not shwn). The light normally liquid hydrocarbons are removed as a light distillate naphtha stream through line 5, a middle distillate stream through line 6, and a vacuum gas oil stream through line 7. The remaining reduced crude is removed through line 8 for further processing. The naphtha fraction and the middle distillate fraction are passed to hydrotreating zones 9 and 10, respectively. The middle distillate hydrotreated stream is removed in line 11 and is in the kerosene boiling range hydrocarbons. The hydrotreated naphtha stream is passed through line 12 to a reformer 13 where it is catalytically reformed to produce a reformate containing C g to C g arαnatic hydrocarbons and C g + paraffinic hydrocarbons and hydrogen. The hydrogen is removed, as a by-product, overhead in line 14. The catalytic reformate is fed through line 15 to a fractionating column or splitter 16 in which a portion of the C g + paraffinic hydrocarbons can be removed through line 23 and fed to the gasoline product pool. The remainder of the reformate, containing C g to C_ arαnatic hydrocarbons, particularly benzene, any remaining υnseparated C g + paraffinic hydrocarbons and possibly C 8 - paraffinic hydrocarbons, is fed frαn the fractiαnatiαn column 16 via line 17 to the riser reactor 29. The fractionation column 16 thereby functions to control the amount and opposition of the C 6 -C 8 light arαnatic hydrocarbon stream that is fed to reactor 29. Alternatively, particularly with light reformate streams, the fractionating step can be omitted and the entire reformate effluent stream can be fed directly to the riser reactor 29. The vacuum gas oil removed through line 7 is fed to a fluidized bed catalytic cracking zone 18 which includes a fractionating column 19. The overhead vapor stream from the fractionating column 19 is removed in line 20, compressed in compressor 20a and cooled and condensed in condenser 21 and then fed to receiver 22. The condensate collected in receiver 22 is fed through line 24 to a primary absorber 25. The uncondensed gases in receiver 22 containing C.- olefins are removed overhead through line 26 and fed to primary absorber 25. Alternatively, the uncondensed gases in receiver 22 containing the c 4 - olefins can be fed via lines 26, 26a and 28 directly to the riser reactor 29. A liquid stream is removed from the fluid catalytic cracker fractionating column 19 through line 27, is cooled in heat exchanger 27a and is fed to the top of the primary absorber 25. An overhead gas stream including c 4 - olefins is removed from absorber 25 in line 28 and is fed through lines 28a and 28b to zeolite catalyst riser reactor 29 in which it is contacted with the catalytic reformate including C g to C_ arαnatics fed through the line 17. The bσtt n line 30 from the primary absorber 25 containing C~ gasoline product is debutanized and treated, by means not shown, and is fed to the gasoline product pool. The ethene and propene in the C - feed in lines 28, 28a and 28b are contacted with the Cg to C g arαnatics in the riser reactor 29 to alkylate the arαnatics and form alkyl arαnatic hydrocarbon gasoline product. The riser reactor 29 product is removed from the reaction zone via line 31 and passed to separator 32. The overhead vapor products frαn separator 32 are fed via line 38 to absorber 33 and contacted with a suitable absorber oil fed through line 34 to remove C-+ hydrocarbons and absorber oil via line 35. The overhead line 36 frαn absorber 33 contains C3- hydrocarbons. Bie absorber oil and C 3+ hydrocarbons in line 35 are treated to separate the C 3 + hydrocarbons and recycle the absorber oil. The bottoms frαn separator 32, comprising the C 5 + hydrocarbon and C_ to CL. alkyl arαnatic hydrocarbon gasoline products, are removed via line 37 and fed to debutanizer 40 frαn which an overhead C 4 gas stream is removed via line 41. The debutanized alkylated arαnatic hydrocarbon gasoline product is removed via line 42 and is fed to the gasoline product pool. Referring to Figure 2, in said one preferred example, the Cg to C g arαnatic reformate fraction is removed frαn the splitter 16 through line 17 via pump 101 and heat exchanger 102 to a distribution plate 105 in the bottom of riser reactor 29. The heat exchanger 102 preheats the Co. to Co 0 reformate prior to feeding it to the riser reactor. A C. paraffin stream can be removed through line 103 and via valve means 104 and sent to the gasoline pool. The remainder of the CL paraffins can be recycled thrαu ι line 104a to the splitter 16. The C.- li t olefin fuel gas in line 28 is separated into three portions as lines 28a, 28b and 28c.20 to 50% of the fuel gas is fed through line 28a, mixed with the C 8 -C 8 reformate feed in line 17 and fed to the distribution plate 105 in the bottom of the riser reactor. 20 to 40% of the fuel gas feed is fed through line 28b at an intermediate point in the height of the riser section of the reactor and the remaining 20 to 40% of the fuel gas feed is fed at an upper point in the height of the riser section of the reactor through line 28c and through line 28d in the upper fluidized catalyst bed section. The C - fuel gas feed is distrituted through lines 28a, 28b, 28c and 28d in a manner such that the wei t ratio of C g to C g arαnatics to C_ and C 3 olefins in the fuel gas feed in the riser section and the upper fluidized catalyst bed section of the reactor during the reaction is maintained at 12:1 to 15:1. The Cg-Cg arαnatics and the C.- fuel gas are contacted with regenerated ZSM-5 catalyst fed to the bottom of riser reactor 29 through catalyst return line 106 via flow control means 107 and with recycled catalyst fed through catalyst recycle line 112. The regenerated and recycled catalyst are lifted in the riser section 108 of the reactor to the upper fluidized catalyst bed section 109. The Cg- arαnatics, the C 4 ~ fuel gas and the alkyl aromatic product act as the lift gas for the catalyst in the riser section of the reactor. The alkylatiαn reaction is carried cut primarily in the riser section 108 at a teπperature of 600 to 700 β F (315 to 371"C) and at a pressure of 150 to 250 psig (1135 to 1825 kPa). The reaction heat can be partially or completely removed from the reaction zone by using cold or only partially preheated reformate and cold or only partially preheated C.- fuel gas feed. The transfer gas velocity in the riser section of the reactor is 10 to 20 ft/sec (3 to 6 m sec). A dilute solids gas phase is withdrawn frαn the top of the reactor and fed to a gas solids separation zone 111 which contains a sintered metal filter and in which the solid catalyst particles are disengaged and separated frαn the hydrocarbon product gas. All of or at least a portion of the separated catalyst particles are returned to the bottom of the riser reactor through catalyst recycle line 112 and mi ed with regenerated catalyst introduced through catalyst return line 106. The separated hydrocarbon product is withdrawn through line 113 and fed to separation vessel 114. The Cg+ gasoline hydrocarbon stream containing the allyl aromatic product is withdrawn through line 115. An overhead stream cxxitaining C.- hydrocarbons is withdrawn th__ough line 116 and is fed to the FCC sponge absorber. The residence time of the reformate feed and fuel gas feed in the riser reactor is 3 to 7 sec. In this exaπple regeneration of the partially deactivated catalyst is effected with hydrogen. Thus 12 to 170 %/hr of the catalyst inventory is continuously withdrawn frαn the upper fluidized bed section of the reactor and transferred by catalyst outlet means 117 through valve control means 118 to catalyst regenerator 119. The partially deactivated catalyst in line 117 is entrained in hydrogen regeneration gas provided from the reformer 13 via line 120 and transported via riser 121 to the top portion of the regenerator vessel 119. The main portion of the hydrogen regeneration gas is introduced into the regenerator 119 via line 122 and distributor plate 123 to effect fluidizatiαn of the catalyst in the fluidized bed 124. A sufficient amount of hydrogen regeneration gas is fed to the regenerator to maintain the catalyst as a fluidized bed. The teitperature in the regenerator is maintained at 700 to 1200*F (371 to 649*C) and at about the same pressure as the riser reactor. The stripped hydrocarbons and the hydrogenated coked hydrocarbons are removed from the regenerator 119 through line 125 and taken far separation and further processing. Alternatively all or a partial of the withdrawn hydrocarbons can be returned to the riser reactor through line 126. Catalyst particles in the dilute phase 127 of the regenerator are disengaged from the fluidizing gas in cyclone separator 28 and returned to the regeneration zone through dip leg 129. The effluent gases from the regenerator can be treated to separate the hydrogen regeneration gas frαn the hydrocarbon products and the separated hydrogen can be recycled to the regenerator or recovered. The regenerated catalyst ccπta__ning only a small residual amount of carbon is withdrawn from the regenerator through catalyst withdrawal line 106 via valve control means 107 and fed to the bottom of the riser reactor 29 and is contacted with fresh reformate and fuel gas feed. Referring to Figure 3, the constrtictiαn and operation of the riser reactor in this further example are similar to those of the Figure 2 example. However, in the Figure 3 example regeneration of the partially deactivated catalyst is effected with oxygen. Thus 5 to 150 %/hr of the catalyst inventory is continuously withdrawn frαn the upper fluidized bed section of the reactor and transferred by catalyst outlet means 130 through valve control means 131 to catalyst stripper vessel 132. The partially deactivated catalyst is maintained as a fluid bed in the stripper zone 133 at a pressure within about plus or minus 20 psi of the pressure in the regenerator and is contacted with an inert stripping gas such as nitrogen. The nitrogen stripping gas is introduced into the bottom of the stripping zone through line 134 and distribution plate 135 at a sufficient rate to maintain a fluidized bed in stripping zone 133. The partially deactivated catalyst in the stripping zone is stripped of substantially all of the hydrocarbon product, leaving on the catalyst substantially only deposited coke. The stripped hydrocarbon product is returned to the reactor through outlet line 136 and 137 far recovery of the hydrocarbon. The stripped catalyst containing deposited coke is withdrawn frαn the stripping zone through stripped catalyst cutlet line 138 and valve control means 139. The stripped catalyst is entrained in an air regeneration gas provided via line 140 and transported via riser 141 to the top portion of the regenerator vessel 142. The main portion of the regeneration gas is introduced into the regenerator 142 via line 143 and distributor plate 144 to effect fluidizatiαn of the stripped catalyst in the fluidized bed 145 of the regeneration zone. The stripped partially deactivated catalyst is contacted in the fluidized bed of the regenerator 142 with an oxygen containing regeneration gas such as air to effect combustion of the coke and removal of the coke frαn the catalyst and regeneration of the catalyst. A sufficient amount of the oxygen containing regenerating gas is fed to the regeneration zone via line 143 and distribution plate 144 to maintain the catalyst as a fluidized bed. The teπperature in the fluidized bed is maintained at 800 to 900 β F (427 to 482 β C) by controlling the amount of oxygen containing gas introduced to the regeneration zone. The pressure in the regenerator is about the same pressure as that in the riser reactor. The regeneration gas advantageously can be provided from the air regeneration gas feed to the FCC catalyst regenerator. The catalyst particles are disengaged frαn the fluidizing gas, including cxxribustiαn products of the coke and oxidizing gas, in the top dilute phase 146 of the regenerator in cyclone separator 147. The separated catalyst is returned to the regeneration zone through dipleg 148. The effluent gases containing the regeneration combustion gases and excess oxygen withdrawn frαn the regenerator through cutlet line 149 and are conveniently fed to an FCC catalyst regenerator in which the excess oxygen is burned. The residence time of the catalyst in the oxygen regeneration zone is 20 to 180 minutes. The regenerated catalyst cxjπtaining only a small residual amount of carbon typically less than 0.05 wt%, for exaπple, in the amount of about 0.01 to 0.05 wt% based on the weight of catalyst is withdrawn frαn the regenerator through catalyst withdrawal line 106 via valve control means 107 and fed to the bottom of the riser reactor 29 and is contacted with fresh reformate and fuel gas feed. The stripped hydrocarbons in line 136 can be treated to separate and recycle the nitrogen to the stripping zone prior to feeding the stripped hydrocarbons to riser reactor 29. Alternatively the .stripped hydrocarbons can be separately treated to recover the nitrogen and hydrocarbons. The present invention is further illustrated by the following example. Examole The process is carried out in a fluidized bed riser reactor using the apparatus and method of the Figure 2 eα_ιbcd___τ_sπt of the invention. An H-ZSM5 zeolite catalyst having an average steady state cilpha value of 510 is used. The temperature in the riser section of the reactor is about 850*F (454 * C) and the pressure is about 150 psig (1135 kPa). The olefin feed is fed through three injection feed points spaced along the height of the riser reactor. The olefin feed is distributed through the three injection points in a manner such as to maintain an arαnatic to olefin weiφt ratio in the riser section of the reactor of 7:1. The olefin and reformate feed stream compositions are given in Table 3 below. Table 3 Feedstream Compositions Olefin Gas Wt% Hydrogen 2.3 Ethene 12.2 Propene 12.1 Reformate Wt% Benzene 5 Toluene 11.5 CL Arαnatics 18 For purposes of comparison the process is repeated with the exception that all of the olefin feed is introduced in the bottom of the riser reactor and mixed with the reformate feed. The weight ratio of aromatics to olefins in the riser section of the reactor as a result of the single point injection of the olefin feed is 3.5 to 1. The effluent hydrocarbon gas stream in each case is analyzed and the results obtained are reported in Table 4 belcw. Table 4 Wt Ratio Wt% Conversion Wt% Conversion Wt% Oαke Arαnatics/ Arαnatics To Olefin Feed To Based On Olefins Alkyl Aromatics Alkyl Aromatics Olefins Invention 7:1 30 90 0.007 Ccnparisαn 3.5:1 26 85 0.030 Tiie above data show that by maintaining a high weight ratio of arαnatic to olefin feed using multi olefin feed injection in a riser reactor that there is an increase in the conversion of arαnatic hydrocarbons and an increase in the conversion of olefin hydrocarbons to alkyl arαnatic hydrocarbons and a substantial decrease in the coke make.

Claims: WO 90/11266 -22- Clai-ms 1. A process for producing an alkyl arαnatic product, ccnprising contacting a feed stream ccnprising C.- olefins with a feedstream ccnprising C- to C„ arαnatic hydrocarbons at an arαnatic to olefin weight ratio of at least 5:1 in the presence of a fluidized zeolite catalyst in a riser reactor having multiple olefin feed injection points to alkylate the C -C arαnatics with the olefins and produce the required alkyl arαnatic hydrocarbon product. 2. The process of claim 1 wherein the riser reactor comprises a lower riser section and an upper fluidized catalyst bed section and the multiple olefin feed injection points are spaced along the height of the riser section or along the height of the riser section and the upper fluidized catalyst bed section of the reactor. 3. The process of claim 1 wherein the contacting of the C.- olefinic feed stream and the C g to C g aromatic hydrocarbon feed stream is effected at a teπperature of 350 to 900"C (177 to 482*C) and a pressure of 20 to 650 psig (240 to 4580 kPa). 4. The process of claim 3 wherein the contacting is effected at a teπperature of 500 to 800 β F (260 to 427'C) and a pressure of 120 to 420 psig (930 to 3000kPa). 5. The process of claim 1 wherein the zeolite catalyst comprises a zeolite having a s__Hca-tx_*-alumina molar ratio of at least 12 and a cαnstaint index of 1-12. 6. The process of claim 1 wherein the zeolite catalyst comprises ZSM-5. /11266 -23- 7. The process of claim 1 wherein the CL- hydrocarbon feed stream ccπprises 8 to 50 wt.% ethene and 3 to 50 wt.% propene and the aromatics feed stream comprises 10 to 95 wt.% C g to Cg arαnatics. 8. The process of claim 1 and further ccnprising withdrawing a portion of the catalyst frαn the riser reactor, contacting the withdrawn catalyst with hydrogen in a regeneration zone at a teπperature of 700 to 1200 β F (371 to 649*C) to strip absorbed hydrocarbon products, remove coke from the catalyst and regenerate the catalyst and then __eturning the regenerated catalyst to the riser reactor. 9 The process of claim 1 and further comprising withdrawing a portion of the catalyst from the riser reactor, contacting the withdrawn catalyst in a catalyst stripping zone with an inert stripping gas to strip frαn the catalyst the absorbed hydrocarbon product, then transferring the catalyst to a regeneration zone in which the catalyst is contacted with an oxygen-containing gas at a teπperature of 700 to 950 β F (371 to 510 * C) to remove coke frαn the catalyst and regenerate the catalyst and returning the regenerated catalyst to the riser reactor. 10. The process of claim 1 wherein the weicfrt ratio of aromatic hydrocarbons to olefins is 10:1 to 15:1.

Inventors: HARANDI MOHSEN NADIMI, KUSHNERICK JOHN DOUGLAS, OWEN HARTLEY NMN, HARANDI, MOHSEN, NADIMI, KUSHNERICK, JOHN, DOUGLAS, OWEN, HARTLEY (NMN)
Applicants: MOBIL OIL CORP, MOBIL OIL CORPORATION
Application year: 1990
Main classification: C07C2
IPC codes: B01J29, C07B61, C07C2, C07C15, C10G35