GB2136013A - Olefin conversion process - Google Patents

Description

1 GB 2 136 013 A 1

SPECIFICATION

0Iefin conversion process This invention relates to the production of distillate 70 (diesel fuel).

In accordance with the invention it has been unexpectedly found that gasoline feedstocks pre pared in a particular manner can be readily processed into a hydrocarbon productwith a significant fraction boiling in the distillate range.

The said gasoline feedstocks are prepared by conversion of lightolefins, using a zeolite catalyst that is modified as hereinafter described.

The subsequent processing of the said gasoline feedstocks in accordance with the invention may be carried out using a conventional Friedel-Crafts catalyst.

The oligomerisation of light olefins over acid catalysts is well known -see e.g. Kirk-Othmer 85 "Encyclopaedia of Chemical Technology" 3rd Edition 1978 John Wiley-Vol. 4. p.362-this gives a material useful for gasoline blending stock. Higher severity oligomerisation to materials in the distillate range is possible, butthe product, because of much 90 skeletal isomerisation and branching, suffers from low cetane number e.g. tetra-iso-butylene-olefin oli gomer of isobutylene, cetain No. 15, compared with n-hexadecane (cetane), cetane No. 100.

U.S. Patent Nos. 3,894,106,4,062,905 and 4,052,479 95 disclosethe conversion of alcohols and ethers to higher hydrocarbons by contactwith zeolite catalyst having a silica to alumina ratio of at least 12 at about 260to 45M. The preferred zeolite catalysts have crystal densities which are not substantially below 1.6 100 grams per cubic centimeter. These special catalysts are exemplified byZSM-12, as in West German Offenlegungssch rift No. 2,213,109, ZSM-21 and cer tain modified naturally occurring zeolites. The synthe ticzeolites made using an organic cation are pre- 105 ferred.

Aromatization of hydrocarbon feedstocks over zeolites is well known. U.S. Patent No. 3,760,024 discloses an aromatization process for a feedstock comprising C2tO C4 paraffins and olefins comprising 110 contacting such a feedstockwith crystalline alumino silicates of the ZSM-5family. U.S. patent No. 3,756,942 discloses contacting a feedstock having a boiling range of C5to about 250'Fwith a crystalline alumino silicate zeolite of the ZSM-5 type, and US patent 115 4,150,062 describes an invention which relates to improved processing of light olefins of from 2 to 4 carbon atomsto product comprising high octane gasoline components. The process comprises con tacting feedstock in the presence of co-fed water with 120 a catalyst comprising a zeolite characterized by a silicalalumina molar ratio of at least 12.

The crystalline aluminosilicate zeolites used in the catalyst composition of the process of this latter invention are referred to generally asthe ZSM-5 family, or as behaving like ZSM-5, and include ZSM-5, ZSM-1 1, ZSM-1 2, ZSM-35 and ZSM-38.

Olefin oligomerisation overzeolite of the ZSM-5 familysuch as ZSM-1 2 has also been described in US Patent 4,254,295. This disclosed a process for the selective o5gornerization of linear and branched chain C2tO C12 olefins and comprised contacting the olefins, in the liquid phase, with a ZSM-1 2 zeolite attemperatures from about 80'Fto about400'F. ltwas found that the process provided selective conversion of the olefin feed to oligomer products with high selectivity, the product containing little or no light cracked products, paraffins,etc.

Light olefins can be synthesised from alcohols such as methanol using zeolite catalysts similarto those described above, as in for example US Patent 4,025,576. This shows that a feed comprising one or more compounds selected from the lower monohydric alcohols with up to four carbon atoms, and their simple or mixed ether derivatives, at subatmospheric partial pressure, is completely converted to a Mixture comprising mainly light olefins, by contactwith a particulartype of crystalline aluminosilicate catalyst.

Although it is a generally accepted factthat zeolites in the alkali metal form are of substantially less catalytic activity, in some cases completely inactive, the conversion of methanol over alkali metal modified zeolites has been described in US Patent3899544. For conversion of alcohols and ethersto higher hydrocarbons byzeolite catalysts, if thezeolite isfully exchanged so that its cation content is substantially alkali metal, it loses most of its activityto catalysethis reaction. Such high alkali metal contentzeolites do however retain activityfor some catalytic roles, notably the dehydration of alcoholsto ethers.

When most of the alkali metal is exchanged outof the zeolite and replaced by acid sites, (for example by ammonium exchange followed by calcination to liberate ammonia and leave a proton within the zeolite, or as in the case of acid stable zeolites such as ZSM-5, by direct exchange in acidic media) the catalyst is extremely active for converting alcohols andlor ethersto higher hydrocarbons. For example, in the conversion of methanol to hydrocarbons in contactwith an WZSM-5 zeolite catalystfrom which most of the alkali metal (usually sodium) has been removed, the hydrocarbon yield at 100% feed conversion is consistently about44weight percent, based upon methanol fed (i.e. little conversion to dimethyl ether and other oxygenates). Where none of the alkali metal has been removed the hydrocarbon yield is zero.

It is an object of the present invention to provide an improved processforthe conversion of light olefins into a hydrocarbon stock a substantial portion of which boils in the distillate range with only a minor portion boiling in the gasoline range.

In accordance with and fulfilling this object, one aspect of this invention resides in the discovery that when the conversion of lower olefins, by which we mean C3-C6 olefins and mixtures thereof, to higher hydrocarbons, particularly hydrocarbons boiling in the gasoline boiling range, e.g. C5 to 196'C, is carried out over a zeolite modified in a particular manner,the resulting gasoline can be readily processed, using for example a Friedel- Crafts catalyst, into a hydrocarbon stockwith a sig nif ica nt fraction boiling in the distillate range. The conversion is carried out at about 100'Cto 4500C, preferably300to 450'C, upto about 50 atmospheres, and about 0.5 to 50 liquid hourly space 2 GB 2 136 013 A 2 velocity.

The catalyst modification which makes possiblethe improved operation described herein isto ensurethat a significant portion of the cation sites of the aforementioned zeolite is occupied by basic cations, notably Lewis or Bronsted bases such as elements of Group]a, lla orVa of the Periodictable. Specific cationswhich have been foundto be particularly useful arethose which contain sodium, potassium, calcium, nitrogen and phosphorus, eitheralone or in 75 appropriate cationic complexform.

The zeolites used as catalysts are usually obtained from a composition containing an organic cation.

After initially producing the zeolite crystal structure desired with its original organic and alkali metal - 80 cations, it is dried, and then may be directly calcined, in which casethe organic cations are removed by oxidation to produce a zeolite containing alkali metal cations. The alkali metal can be exchanged eitherwith other metal ions orwith ammonium ions or both. 85 Where acid sites are desired ammonium cations are used. The ammonium form of the zeolite, upon calcination to remove ammonia, leaves the hydrogen form of the zeolite. The orderof exchange and calcination is variable with several different sequ- 90 ences of operation reported to give special results for particular purposes well known in the art.

The catalyst of this invention can be prepared by converting all of the cationic sites to the alkali metal form and then exchanging a proportion of the alkali 95 metal cations for acid or other "active" cations.

Alternatively an acid form zeolite can be subjected to exchange with appropriate alkali metal moieties.

Another method of obtaining the catalyst of this invention is to mix the hydrogen (acid) form of the 100 zeolite with a solid matrix or binder which has available alkali-cations. Although we do not wish to be limited by any theoretical orpostulated mechanism fortheobserved beneficial results, we observe that, afterthe influenceof calcination, the composite 105 catalyst performs as if a portion ofthezeolite componenthad been exchanged byalkali metal.

Another method of obtaining the catalyst of this invention isto use the as-made zeolite; that is, a zeolite containing both organic and alkali metal cations, and 110 calcining the zeolite (with orwithout binder, as powder or pellet) so as to remove a portion of the organic cations. Itwill be appreciated thatthe relative amount of organic and alkali-metal cation will be dependent on such things as the nature of the organic moiety, the relative concentrations of organic and alkali-metal in the synthesis-gel and to some extent the silica-alumina ratio of the zeolite, the relative proportion of which can be adjusted by methods well known to those ski] led in the art. It will also be appreciated that in this embodiment, the catalyst is not subjected to ion exchange after synthesis (see examples 13,20,27 and 32 below).

Accordingly,the invention provides a process for conversion of lower olefinsto hydrocarbons boiling in 125 the gasoline boiling range, characterised in thatthe lower olefins are converted by contactwith a zeolite catalystwhich has been modified bysubstituting a significant portion of the cation sitesthereof by basic cations, wherebythe gasoline produced is capable of 130 further processing into a hydrocarbon product with a significantfraction boiling in the distillate range.

In a preferred embodiment of the invention the catalyst comprises a zeolite and a binder, said catalyst containing at least 0.2%, preferably at least 0.3%, of exchangeable basic cations, determined as oxide, on thetotal weight of the catalyst.

The catalyst may comprise up to 90% byweight binder, such as bentonite or alumina, but is preferably within the range of 25% to 75%.

The zeolite is preferably of the ZSM family, having an A1203 content of at least 1 % byweight. Whilstthe lower limits of alumina, and hence alkali metal, in the zeolite are determined bythe need forsufficient catalytic activity,the upper limits are determined by the maximum level of zeolitic alumina that can be tolerated by a given zeolite. Forexample, it!swell known thatZSM-5 will typically have maximum alumina contents at about 4.5% byweight; in this case the maximum alkali-metal contentwould correspond to about80% of thisvalue, calculated on a molar basis. Otherzeolites can have much higher alumina contents,so thatthe corresponding maximum alkali contentwould be proportionally higher.

Those skilled in the artwill realizethat, on the basis of the above,the catalyst (zeolite plus binder) of the present invention preferably has 20% of the exchangeable basic cations on a molar basis relative to the alumina content of the zeolite. More preferably the figureis30%.

In a further preferred embodiment of the invention a process for production of diesel fuel comprises the following steps:- (a) converting lower olefins attemperatures between about 100to 450'C, preferably between 260to 450'C and more preferably between 300 and 450'C, pressures up to about 50 atmospheres, and LI-ISV of about 0.5 to 50hr-, in contactwith a zeolite catalyst which has been modified bysubstituting a significant portion ofthe cation sitesthereof by basiccations, preferably a catalyst comprising a zeolite and a binder, said catalyst containing at least 0.2%, and preferably at least 0.3%, of exchangeable basic cations, determined as oxide, on the total weight of the catalyst, to produce a first hydrocarbon product containing hydrocarbons boiling in the gasoline boiling range; (b) converting the said first hydrocarbon product by contact with a Friedel-Crafts catalyst into a second hydrocarbon product a substantial portion of which boils in the distillate range with only a minor portion boiling in the gasoline range.

Preferablythe second hydrocarbon product comprises at least40%, and more preferably at least50%, byweight distillate boiling at >2350C, and preferably less than 50%, and more preferably less than 40%, by weightgasoline.

It has been noted that a zeolite catalyst of this invention has alkali metal and acid cationic sites. It may also have other cationic sites, such as hydrogenation/dehydrogenation components, incorporated for given purposes. These other sites are to be considered as part of the acid site group and are notto be considered as replacing alkali metal cation moieties. These additional components can be incorporated with the zeolite catalyst by impregnation, vapor c 3 GB 2 136 013 A 3 deposition orexchange, as may seem desirable.

It has been ascertained thatthe catalysts of this invention are capable of converting alcohols such as methanol into an olefinic gasoline, butthe catalyst deactivates quickly, e.g. over a period of about five hours on line, making practical use of these catalysts foralcohol conversion difficult. Surprisingly, ithas been found that olefin conversion over the catalysts continuesto giveuseful yieldsof liquid productfor - much longerperiods, e.g. greater than thirty hours on line before reactivation, by for example air-calcina tion, is required.

The present invention hasfurther ascertained that the product hydrocarbon stock produced from olefins over alkali-metal containing zeolites such as described above can be easily converted bytreatmentwith a Lewis acid catalyst such as aluminium chloride into a product rich in distillate fraction. The catalyst particu larly useful forthe conversion of the hydrocarbon stock can be termed a Friedel-Crafts catalyst, a detailed description of which can be fou nd in -Friedel-

Crafts and Related Reactions" G. A. Olah (ed) Vols 1-4, Interscience, 1963-65.

The invention will be further illustrated bythe following non-limiting examples.

Example 1

This example describesthe synthesis of ZSM-5with a high sodium content.

Aluminium wire (2.519) was dissolved in sodium hydroxide solution (15.29 in 1009 water). The solution was then added to colloidal silica (6679 of Ludox HS40 90 (trade mark), 40% Si02) and stirred. Tetrapropylam monium bromide (1 47.8g) in water (1 000g) was then added and the whole vigorously stirred to a homogeneous gel. The gel was stiffened bythe addition of sodium chloride (250g). The zeolite was crystallized from the mixture by heating the gel in an autoclaveto 17WC, with stirring, for 16 hours. The zeolitewas obtained from the mother liquor by filtration and washing with distilled water. The as made zeolite was then washed with 2M-hydrochloric acid and then calcined (50WC in moist airfor 16 hrs.).

The productanalysed at 1.46% A1203 and 1.74% Na20 (i.e. all AI expressed as Wt % A1203 and all Na expressed at Wt % Na20).

Example 2

This example describes a further synthesis of high sodium content ZSM-5.

The zeolite was prepared in an analogous mannerto that described in Example 1 exceptthat the weig hts of active corn ponents were: aluminium wire (1.28g) sodium hydroxide (7.5g); colloidal silica (336.6g), tetra-n-propylammonium bromide (73.9g). The same quantities of waterand sodium chloridewere used as for Example 1. After acid washing, calcination and drying, the productwas analysed at 1.18% A1203 and 0.8% Na20.

Example3

This describesthe conversion of propylene over high sodium ZSM-5.

Samples of zeolite from examples 1 and 2 were mixed with bentonite (33% by weight bentonite) and water, then extruded. The extrusions (3mm) were dried and calcined at 50WC. They were then charged (72g plus 40g of inert alumina spheres) into a downflowtubular reactor. Propylene was passed at 36 litres/hr overthe catalyst at about 30WC and the liquid products condensed (1 23g of liquid). The liquid was analysed by gas-chromatography (12.5m, SP21 00, fused silica column) and a simulated distillation profile obtained. The results are shown in Table 1 and indicate the product consists predominantly of material boiling in the gasoline-range. Table 1 Simulated Distillation Profile of Liquid Product from Example 3.

Fraction Simulated Boiling Range wt % gasoline <l96UC 93.4 jet-fuel 196 2350C 4.3 middle distillate 1 235 - 317'C 1.7 middle distillate 2 >317'C 0.7 Example 4

This describes the conversion of the liquid product obtained in Example 3 into material boiling in the distillate range.

The liquid (30g) and anhydrous aluminium chloride (10g) were refluxed (for3 hours).The mixture was then hydrolysed by shaking with water (approx. 200 cc) and the hydrocarbon fraction obtained by separation and filtration. The liquid productwas subjected to the same chromatographic analysis as in Example 3; the results of the simulated distillation profile are shown in Table 2 and clearly demonstrate the increase in boiling points obtained byAlC13treatment. Table 2 Simulated Distillation Profile of Liquid Product from Example 4.

Fraction Simulated Boiling Range Wt % 1 gasoline <196 C 28.6 jet-fuel 196 - 235'C 12.9 middle distillate 1 234 - 317'C 27.8 middle distillate 2 M7'C 30.

6 Example 5

This describesthe conversion of propylene over 95 acid ZSM-5 (H-ZSM-5).

H-ZSM-5was obtained by a preparation similarto that described in Example 1. Thefinal product was converted into a low sodium form by further washing the produetwith 2M hydrochloric acid,then giving the product a further calcination. The productwas fabricated into extrudates (as described in Example 3) and used to convert propylene (251- 1hr over47g of catalyst at approx. 350'C). The resulting liquid product (629) was subjected to the same gas-chromatog- raphic analysis as described in Example 3. The results are shown in Table 3 and illustratethe product had a very similar boiling-point profile as the product of Example3. Table 3 Simulated Distillation Profile of Liquid Product from Example 5.

Fraction Simulated Boiling Range wt % gasoline <l9CC 91-9- jet-fuel 196 2350C 5.7 middle distillate 1 235 - 3170C 2.2 middle distillate 2 317'C 0.5 Example 6 The liquid productof Example 5wasthentreated 4 GB 2 136 013 A 4 with aluminium chloride as hydrolysed as described in Example 4. The resultant liquid was again analysed by gas-chromatography and the simulated distillation profile obtained (Table 4). Comparison of Tables 4 and 2 demonstrated the ineffectiveness of the Friedel-Crafts treatment in Example 6 in that the major portion of the product remains in the gasoline boiling-range. Table4 Simulated Distillation Profile of the Product obtained from Aluminium Chloride Treatment of Liquid Product obtained from Example 5.

Fraction Simulated Boiling Rapge Wt % gasoline 196'C 76.9 jet-fuel 196 2350e 5.7 middle distillate 1 235 - 3170C 4.6 middle distillate 2 3170C 12.8 Examples 7-13

These examples describe the characteristics of 35 catalysts used in following examples.

Table 5 (a) hot spot temperature.

(b) gg-1 of propylene converted.

(c) Ratio of aromatic proton intensitylolefin proton intensity by1H N.M.R.

(d) from G.L.C.

Examples 14and 15 illustrate that extensive exchange of thezeoliteto remove alkali-cation results 70 in higher aromatic content gasoline than if the zeolite is ion-exchanged and calcined just once (Examples 16-18). Example 19 illustrates that excessive back exchange with sodium ions may reduce unduly the activity of the catalyst (liquid yield -0.34gg-1 (a) analyses, on a weight basis, of a 211,zeolitel bentonite extrusion, expressing all metal as its oxide. (b) notdetermined.

(c) molar. (d) impurity in bentonite.

The zeolites were synthesised by crystallisation of silicalalumina gels using tetra-n-propylammonium cation as organictemplating cation. Theywere modified to differing sodium content as illustrated in Table 5. In examples7 and 8the catalystswere made from the "as-made"zeolites by [onexchanging with hydrochloric acid (2Mand calcining the catalyst twice. The sodium contentof the zeolitabefore fabrication was very low. The zeolites werethen mixed with bentonite 211, Mw and formed into extrusions. For catalysts in Examples 9, 10, 11, the zeolites (from separate syntheses) were ion-exchanged and calcined only once. The catalyst of Example 12 wasthe same as Example 11, butwas furtherwashed with ammoniumlsodium ion solution. The catalyst of Example 13 wasthe "as-mad&' zeolite i.e. received no ion-exchangesorcalcinations before mixing with bentonite and forming into a catalyst. This illustrates the effect of leaving the tetra-n- propylammonium cations in the zeolite. Examples 14-20 These examples illustratethe use of catalysts of Examples 7-13to prepare gasolines of varying olefinic content. Propylene, at 1 atm. pressure,was passed over a packed bed ofthe catalyst held at 3000C. After cooling to ambientthe product gasolines were collected and the quantity of aliphatics present determined by N MR and GLC, and the gasolines characterised by RON (clear). The results are given in Table 6.

-W Zeolite Catalyst Analysis (a) Analysis Example Code sio 2 /AI 2 0 3 14sio 2 /AI 2 0 3 %Na 20 We 2 0 3 (c) (d) 7 AI 95 86.o 7.4 0.56 (b) 8 A2 40 80.8 8.0 0.88 (b) 9 A3 95 85.9 7.6 0.68 1.33 A4 40 78.5 8.0 1.31 1.19 11 AS 95 77.5 6.4 1.18 1.08 12 A6 95 82.0 7.0 1.28 1.21 13 A7 95 79.2 7.2 1.50 1.26 Example Catalyst WHSV Max Te.p Liquid I(A10) 7liphatics RON (hr-1 (OC), (a) Yield (clea) (b) (c) (d) 14 W 2.4 483 0.50 9.0 41.3 100.0 is Ex8 1.5 455 0.47 4.7 53.5 98.6 16 EX9 2.2 445 0.49 0.5 79.5 95.5 17 Ex10 1.6 449 0.59 1.7 80.9 96.8 18 EX11 2.6 410 0.47 0.19 81.5 95.5 19 Ex12 2.8 433 0.34 0.20 83.3 92.3 Exl.3 0.9 383 0.58 0.34 75.2 J 1 propylenefed). Example 20 illustratesthat "as- made- catalystswhich may retain significant portions of alkyl quaternary cations andlor their decomposition products are effective catalysts. It should be noted that all products were acceptable as gasolines of high (> 90) RON (clear). Examples21-27 These illustrate the conversion of the gasolines described in Examples 14- 20 into products boiling greaterthan 1960C.

Samples of gasolines described in Examples 14-20 weretreated with anhydrous aluminium chloride GB 2 136 013 A 5 under ref lux conditions. After three hours the reaction was stopped by adding water. The organic phase was separated and analysed by a G.L.C. simulated distillation technique and by N.M.R. The results are 5 giveninTable7. Table 7 Product B.P. - (simulated distillation) Example Product I(A/0) <196 196-235 235-317 >317 From 0 c oc 0 c 0 c 21 Ex 14 6.8 69.4 10.0 9.3 11.3 22 EX 15 2.7 51.2 10.0 16.3 22.5 23 EX 16 0.4 49.1 8.4 20.2 22.4 24 EX 17 0.4 45.1 17.0 22.4 15.6 EX 18 0.3 25.6 12.2 29.6 32.6 26 EX 19 0.4 33.6 8.7 25.1 32.6 27 Ex 20 0.3 30.3 11.1 27.0 31.6 Although all the gasoline feedstocks gave some products higher in boiling pointthan gasoline (<l WC),the products of Examples 21 and 22 in which the zeolite had received multiple ion exchange and calcination were inferiorto the other products. Although Example 23 is similar to 22, the perform- ance in the former case is preferred because more product in the middle distillate range (235-317oC) is obtained. These examples serve to illustrate that good yields of middle distil late and higher products can be obtained from propylene by using catalysts of high exchangeable alkali-content, and that excessive removal of the alkali by ion-exchange hindersthe production of distillate boiling products (Examples 21 and 22).

From the above itwill be evidentthat preferred catalysts are represented by Examples 1, 2,9, 10, 11 and 13.

Examples 28,29 These examples serve to illustrate the effect of on-stream time on the conversion of propylene to gasoline over the alkali-metal containing zeolites.

The results are given in Table 8. As can be seen the performance of both catalysts changes with time-onstream, butthe preferred catalyst (Example 29) is that one containing a zeolite with only one ion-exchange treatment and where the change in performance is less severe. Both catalysts produce high yields of aromatics at early time on line butfor the preferred catalyst, this aromaticyield rapidlyfallsto a very low valuewithin 340 min. on-stream- time. Table 8 ExamDle 28 Catalyst Ex-8, WHSV = 1.1hr -1 Time Max Temp Liquid I(A/0) Mliphatics on- (,c) Yield stream (9g-1 propene (min) converted) 455 0.41 17.6 33 309 449 0.51 6.1 46 509 (424) 0.57 1.8 49 751 433 0.53 1.2 60 996 452 0.39 0.8 67 1212 447 0.41 0.6 66 ExamDle 29 Catalyst EX-10, WHSV 1.6hr -1 Time Max Temp Liquid(a) I(A/0) Mliphatics on- (OC) Yield stream (gg-1 propene (min) converted) 449 0.54 8.6 45.0 340 437 0.65 0.4 71.0 475 423 0.65 0.1 90.0 610 424 0.64 0.2 83.5 820 416 0.61 0.3 87.6 920 413 0.59 0.3 90.6 1105 398 0.49 0.01 89.4 1260 392 0.47 0.01 90.8 Examples30,31

These illustrate the conversion of butylenes over the preferred catalyst as described in Exam ple 9. The resu Its a re given i n Ta ble 9. These resu Its show that lig ht olefins such as 1 -butene a nd isobutene can be converted to ol efin ic gaso 1 i nes over the a] ka 1 i-m etal containing catalysts.

Experi ments usi ng ethyl ene fai 1 ed to 9 ive sig nifica nt yields of gasol ines u nder si mi la r conditio ns.

6 GB 2 136 013 A 6 Example 30 1Butene Feed WHSV 1hr- 1 Max Time On-Line Temp Liquid Yield X(A/0) %Aliphatics (min) (0c) (gg-1 1-butene converted) 1180 366.64 0.5 76.4 335 361.76 0.2 74.6 359.77 0-2 76.4 358.73 0-1 79.1 28 718 354.78 0.1 77.7 Example 31 Isobutene Feed WHSV = 1hr-1 Time On Line TOC Liquid Yield I(A/0) %Aliphatics (min) (max) (9g-1 isobutene converted) 348.64 0.4 70.9 290 344.73 0.2 75.8 445 342.73 0.1 78.6 595 340.72 0.1 78.4 760 340 -80 0.1 77.7 970 340.71 0.08 78.2 1270 340.78 0.07 80.4 1425 325.64 0.07 80.1 (a) g.g. of propylene fed, average value.

The calcium treated zeolite (Example 33) gives an olefinic gasoline with acceptable yield. The zinc treated catalyst (Example 34) appears only useful at lowtemperatures, higher temperatures giving higher yields of aromatics. Examples 35-42 These examples serve to illustrate that olefinic gasolines produced bythe preferred catalysts can be converted, by a variety of catalysts, into a product containing significant quantities of kerosene, distillate and fuel-oil. The results are shown in Table 11, where an olefinic gasolinefeed was obtained from propylene using the catalyst described in Example 9.

From the results, aluminium chloride, boron trifluoride on silica-alumina, aluminium chloride on silica alumina, and phosphoricacid on kieselguhr gave reasonable yields of products higher in boiling pointthan gasoline. Hydrogen fluoride treated silica- alumina gave somewhat loweryields, as did the zeolite of Example 42.

These results illustrate that distillate range products can be produced from the olefinic gasolines described above by a wide variety of solidacid catalysts, as well as homogeneous catalysts such as aluminium chloride. Table 11 Example 32

This il iustrates the beneficial use of potassium as alkali-metal to influence the performance of the zeolite.

A catalyst was formed in a similar mannerto that described in Example 13 except in thatthe starting gel contained only potassium as the alkalimetai.

Reaction with propylene, in a similar manner to that described in Example 20, gave a gasoline of very low aromaticcontent (I(A10) <0.1) with a RON (clear) of 96.1. Examples33and34 These illustratethat alkaline earth cations of Group lla beneficially produce an olefinic gasoline butthose of Group lib give an aromatic gasoline.

Zeolites similarto those described in Examples 7 and 1 were treated with calcium and zinc exchange solutions respectively. After exchange and forming into extrusions (211, zeolitelbentonite) the catalysts contained 3.50% CaO and 0.77% ZnO respectively.

Propylene was passed overthe catalysts in a similar mannerto that described for example 14-20.

The results are given in Table 10. Table 10 Exchange WHSY T'C Example Cation (hr-1) (max) Yield (a) I(A/0) 33 Ca 0.9 412 0.50 0.36 34 Zn 1.84267 0.42 0.63 466 i 0.22 16.7 i T 7 GB 2 136 013 A 7 Catalyst Treatment Simulated Distillation Fuel Gasoline Kerosene Distillate Oil Starting Nil 91.6 3.4 3.6 1.4 Gasoline Ex 35 AIC1 3 Reflux 45.5 13.8 32.5 8.2 mins.

t.% A1C1 3 Ex 36 BP on 130'C 55.3 11.5 21.4 11.8 Sii.a- overnight alumina 25 t.% catalyst Ex 37 BP on 1300C 62.6 11.5 17.1 8.9 Si7i.-- overnight alu.ina 12.5 t.% catalyst Ex 38 A1C1 3 on 130oC 68.6 10.4 13.9 7.2 silicaovernight alu.ina 25 wt.% catalyst Ex 39 H PO on 1300C 80.0 10.6 7.6 1.8 k 3e.4 overnight I elguhr wt.% catalyst Ex 40 HF on 130oC 84.8 7.4 5.6 2.3 silica- overnight alumina 25 wt.% catalyst Catalyst Treatment Simulated Distillation Fuel Gasoline Kerosene Distillate Oil x 41 BP 3, HF 1300C 87.1 6.1 4.6 2.2 on silica- overnight alumina 25 wt.% catalyst Ex 42 Example 7 1300C for 87.3 5.0 4.8 2.9 hours wt.% catalyst Example43

Thisexample illustrates that methanol conversion overthe preferred catalyst is unstable,and conversion can onlybe maintainedfora limited onstream5 time.

A down flow reactorwas chargedwith 709 of a catalystformed as in Example9. Methanol (atWHSV -2.1hr-1)was passed over the catalyst at 360'C. A hotspot developed nearthetop ofthe bed, reaching 564C.Afterfive hours on streamthe hotspot had travelledtothe bottom ofthe bed indicating deactivation ofthecatalyst. Itiswell known that conversion fallstovery low levelswhenthe hotspotis lostfrom the catalystbed, hencethe effective useful on- 15. stream-time for methanol conversion was only 5 hours.

Example 44

This example illustrates the conversion of di methylether (1) M E) over a h ig h sodiu m cata lyst.

Dimethylether (1000 m 1 mi n- 1) was passed over a catalyst (70g) as described in Example 43. The details of the conversion are given in Table 12.

8 GB 2 136 013 A 8 Table 72

Time on Set Te.p. Max WIE in Hot spot position line C) Temp gas phase (min Cc) products cumulative) (a) 350 547 nil top of bed 300 350 572 1.8 bottom of bed 420 400 566 6.9 middle of bed 66o 475 579 1.1 bottom of bed 750 475 557 54.4 bottom of bed (a) Liquid products condensed out at ambient temperature.

These results illustrate that the preferred catalysts, although capable of converting dimethylether, can only do so for a limited time on-line and that increasing the bed temperature fails to overcome the activity decay. This is in contrastto conversion of light olefins, propylene, butylene etc., which are able to undergo conversion for much longer periods before regeneration is required.

Claims (19)

1. Process for conversion of lower olefins to hydrocarbons boiling in the gasoline boiling range, characterised in thatthe lower olefins are converted by contact with a zeolite catalyst which has been modified by substituting a significant portion of the cation sites thereof by basic cations, whereby the gasoline produced is capable of further processing into a hydrocarbon productwith a significant fraction boiling in the distillate range.

2. Process according to Claim 1 in which the said basic cations are selected from one or more elements of Group fa, lla orVa of the Periodic Table.

3. Process according to Claim 2 in which the basic 70 cations are selected from one or more of sodium, potassium, calcium, nitrogen and phosphorous, either alone or in appropriate cationic complex form.

4. Process accordingto anyone of Claims 1 to 3 in which the zeolite catalyst includes alkali metal and acid cationic sites.

5. Process for production of diesel fuel, characte rised in that lower olefins are converted into gasoline bythe method of anyone of Claims 1 to4and the gasoline is converted by contact with a Friedel-Crafts catalyst into a hydrocarbon product having a signifi cant fraction boiling in the distillate range.

6. Process for production of diesel fuel, which comprises converting a gasoline produced bythe process of anyone of Claims 1 to 4 bycontactwith a 85 Friedel-Crafts catalystto produce a hydrocarbon producta substantial portion of which boils in the distillate rangewith only a minor portion boiling in the gasoline range.

7. Process for conversion of lower olefi ns to hydrocarbons boiling in the gasoline boiling range, characterised in thatthe lower olefins are converted by contact with a catalyst comprising a zeolite and a binder, said catalyst containing at least 0.2% by weight of exchangeable basic cations, determined as oxide, on the total weight of the catalyst, wherebythe gasoline produced is capable of fu rther processing into a hydrocarbon productwith a significant fraction boiling in the distillate range.

8. Process according to Claim 7 in which the catalyst contains at least 0.3% byweight of exchangeable basic cations, determined as oxide, on the total weight of the catalyst.

9. Process according to Claim 7 or Claim 8 in which the said basic cations are selected from one or more elements of Group]a, lla orVa of the Periodic Table.

10. Process according to Claim 9 in which the basic cations are selected from one or more of sodium, potassium, calcium, nitrogen and phosphor- us, either alone or inappropriate cationic complex form.

11. Process according to anyone of Claims 7 to 10 in which the catalyst includes alkali metal and acid cationicsites.

12. Process for production of diesel fuel, characterised in that lower olefins are converted into gasoline bythe process of anyone of Claims7to 1 land the gasoline is converted by contactwith a Friedel-Crafts catalyst into a hydrocarbon product having a signifi- cantfraction boiling in the distillate range.

13. Process for production of diesel fuel, which comprises converting a gasoline produced bythe process of anyone of Clairns7to 11 bycontactwith a Friedel-Crafts catalyst to produce a hydrocarbon product a substantial portion of which boils in the distillate range with only a minor portion boiling in the gasoline range.

14. Process for production of diesel fuel which comprises the following steps:(a) converting lower olefins at temperatures between about 1 00to 45WC, pressures up to about 50 atmospheres, and LI-ISV of aboutO.5 to 5OhC', in contact with a zeolite catalyst which has been modified by substituting a significant portion of the cation sites thereof by basic cations, to produce a first hydrocarbon product containing hydrocarbons boiling in the gasoline boiling range; 2 1 1 -A r# f 9 (b) converting the said first hydrocarbon product by contact with a Friedel-Crafts catalyst into a second hydrocarbon product a substantial portion of which boils in the distillate range with only a minor portion 5 boiling in the gasoline range.

15. Process for production of diesel fuel which comprisesthe following steps:(a) converting lower olefins attemperatures between about 100to 450T, pressures upto about 50 atmospheres, and WSV of about 0.5 to 50hr-, in contactwith a catalyst comprising a zeolite and a binder, said catalyst containing at least 0.2% of exchangeable basic cations, determined as oxides, on thetotal weight of the catalyst, to produce a first hydrocarbon product containing hydrocarbons boiling in the gasoline boiling range; (b) converting the said first hydrocarbon product by contactwith a Friedel-Crafts catalyst into a second hydrocarbon product a substantial portion of which boils in the distillate range with only a minor portion boiling in the gasoline range.

16. Process according to Claim 15, in which the first-mentioned catalyst contains at least 0.3% of exchangeable basic cations, determined as oxide, on thetotal weight of the catalyst.

17. Process according to Claim 15 or Claim 16 in which the binder comprises up to 90% byweight of the first-mentioned catalyst.

18. Process according to anyone of the preceding claims in which the zeolite is of the ZSM family having an A1203 content of at least 1.0%.

19. Process substantially as described in anyone of Examples 3 to 6 or Examples 14to 33 or Examples 35to 42 or any combination thereof.

Printed in the United Kingdom for Her Majesty's Stationery Office, 8818935, 8184, 18996. Published at the Patent Office, 25 Southampton Buildings, London WC2A lAY, from which copies may be obtained.

GB 2 136 013 A 9