GB2246365A - Hydrocarbon treatment - Google Patents

Abstract

Olefins, which may be sulphur-contaminated, are oligomerized using a supported nickel catalyst having a nickel content of at least 35% by wt. The support may comprise silicon and calcium in a Si: Ca wt. ratio of at least 8:1.

Description

HYDROCARBON TREATMENT This invention relates to the treatment of hydrocarbon feedstocks. In particular, the invention relates to treatment of oleo in feedstocks, especially to a dimerization or other oligomerization process.

Oleo in oligomers are used in various industries in many ways. For example dimers of propylene are used to improve octane ratings in gasoline. Dimers of butene are used in the manufacture of plasticizers; dimers of hexene or trimers of butene are used as intermediates in numerous organic syntheses, e.g., in the preparation of detergents, lubricants, pharmaceuticals, perfumes, and dyestuff 5.

Oligomerization is generally carried out by passing the oleo in feedstock over a suitable catalyst at elevated pressure and, usually, elevated temperature, the combination of temperature and pressure being such that normally the feedstock is in liquid form, separating the resulting higher molecular weight product and, if desired, recycling the unreacted components of the feedstock to the process.

Oleo in feedstocks frequently have sulphur-containing impurities. Thiols, thiophenes, hydrogen sulphide, and other sulphur-containing compounds may make the feed unacceptable because of the propensity for the sulphur rapidly to poison the catalysts used, either in the oligomerization or a subsequent treatment process.

To remove the sulphur from the feedstock before it is passed over the oligomerization catalyst entails an additional step and there accordingly remains a need for a process in which sulphur-bearing olefinic feedstocks can be catalytically oligomerized, and for.a catalyst that is suitable for such a process.

In one aspect of the invention, there is provided a process for the oligomerization of an olefinic hydrocarbon, which comprises treating the hydrocarbon in the presence of a nickel catalyst on a porous support, the catalyst containing at least 35% by weight nickel, based on the total weight of catalyst including support, the support containing silicon and, optionally, calcium, the ratio of silicon:calcium by weight being at least 8:1, in oligomerization conditions and recovering the resulting oligomer.

In a second aspect of the invention, there is provided the use of the said nickel catalyst in the oligomerization of an olefinic hydrocarbon feedstock.

The catalyst has proved remarkably resistant to contamination by sulphur-containing impurities and the invention is directed more especially to a process, and a use, in which such impurities are present in the olefinic hydrocarbon.

The oleo in feedstock may contain C3 to C18, advantageously C3 to C12, more advantageously C4 to C6, olefins, and preferably comprises butene, pentene or hexene. The olefins in the feedstock may be linear or branched and the unsaturation may be internal or terminal. Functional groups or substituents that do not interfere with the reaction may be present in the hydrocarbon. The process is predominantly one of dimerization, especially when the feedstock is a butene, pentene, or hexene.

The feedstock is advantageously contacted with the nickel-containing catalyst at a temperature and under a pressure such that the feedstock is liquid. Appropriate conditions will depend to some extent on the feedstock; for hexene, for example, a pressure within the range of 25 to 35 Bar and a temperature within the range of from 160 to 240"C, advantageously 180 to 2000C, are generally preferred, the precise temperature range depending also on the catalyst. Temperatures above the range indicated above are to be avoided if excessive formation of higher molecular weight oligomers is to be avoided. Within the effective range, optimum temperature will depend also on the catalyst and, during operation, its sulphur loading, higher loadings corresponding to somewhat higher temperatures.

As nickel-containing catalyst, there may be mentioned more especially a catalyst supported on a refractory material, e.g., an inorganic oxide, for example silica, clay, diatomaceous earth (e.g., Kieselguhr), a zeolite, or mixtures of any two or more such materials provided that silicon is present. The silicon:calcium weight ratio is advantageously at least 10:1, and more advantageously at least 20 to 1, and preferably about 30:1, if calcium is present.

Advantageously, the silicon content (of catalyst including support) is at least 5% by weight, preferably 10 to 12% by weight. Advantageously the calcium content (of catalyst including support) is at most 1% by weight and there may be substantially no calcium present at all.

A preferred support is one having a particle size of from 0.5 to 3.0 mm, surface area of at least 50m2/g, a bulk density of from 0.3 to 1.5 g/ml, an average pore volume of from 0.1 to 1.1 ml/g and an average pore diameter of about 3 to 500 nm.

The catalyst is advantageously a reduced nickel catalyst. In particular, it is preferred that the catalyst should be substantially fully reduced, and advantageously at least 80%, preferably, at least 90%, of the nickel present should be in the metallic state at the beginning of the operation. It is believed that during operation on a sulphur-containing olef in, a sulphide of nickel, or a mixture of sulphides of nickel, is formed.

At any time during the reaction, advantageously at most 20%, and preferably at most 10%, of the nickel present is in the form of an oxide.

Advantageously, the catalyst has a nickel content of at least 35%, preferably at least 40%, and most preferably from 45 to 65%, by weight, based on the total weight of catalyst including support if present.

As examples of suitable catalysts there may be mentioned Girdler G-49 RS, a nickel catalyst supported on Kieselguhr, or Girdler G-134 A RS; Ni 5124T or Ni-5126T (which has a Si:Ca weight ratio of 15:1), or Hoechst Ni55/STS.

The rate at which the olefin may be passed over the catalyst will vary with the olef in, the catalyst, the maximum proportion of sulphur tolerable in the treated product, and the level of sulphur already in the catalyst. Advantageously, however, a space velocity in the range of 1.4 to 2.2 v.v.hr1, and preferably 1.6 to 1.8 v.v.hr1, is employed.

The reaction is advantageously carried out in substantially non-hydrogenating conditions, preferably under completely non-hydrogenating conditions, with substantially complete exclusion of hydrogen.

Advantageously, also, the presence of oxygen or oxidizing atmospheres generally is also avoided.

It has surprisingly been found that spent nickel catalyst from other operations carried out on sulphurfree feedstock, e.g., hydrogenation, may be used as the catalyst. Such catalysts contain carbon, or carbon compounds, at a level, measured as carbon, of up to 20, more usually 5 to 20, and more specifically 8 to 15 per cent, by weight based on the weight of catalyst including support. The present invention accordingly also provides a process for oligomerization of an olefin-containing hydrocarbon feed using a spent hydrofining nickelcontaining catalyst. The invention still further provides the use of a spent hydrofining nickel-containing catalyst for oligomerization of an olefin-containing hydrocarbon feed, more especially one containing sulphur.

The process of the invention has the considerable advantage that there is little or no hydrogenation of the olefins, the paraffin content of the products not differing significantly from that of the feed.

The following Examples illustrate the invention: Comparison Example A A tubular reactor of 13.7 mm diameter, 207 mm length, was loaded with 29.0 g of fresh Harshaw Ni-5124T catalyst, which contains 61% nickel, 4% silicon, and 0.4% calcium, as well as 6% aluminium and 0.1t iron, by weight. After a nitrogen purge at ambient temperature, the reactor was immersed in a fluidized sandbath to maintain it at a constant temperature within a desired, in this example 1650C to 1750C, operating range. An olefinic (primarily hexene) feedstock having the analysis shown in Table 1 was passed through the reactor.

TABLE 1 Carbon number distribution - see Table 3 Paraffin content (C6) 9.8% Sulphur 120 ppm Chlorine 2 ppm S.G. (20/200C) 0.693 Maleic Anhydride Value 0.25 mg/g ASTM D1078 Distillation - see Table 4 The catalyst was on stream for a total of 473 hours; although during operation there was a steady build up of sulphur on the catalyst, the sulphur content of the product after run No. 2 at no time exceeded 2 ppm and for much of the time was below 1 ppm. Substantially sulphurfree products were also obtained in the examples according to the invention. The details of reaction conditions at various intervals are shown in Table 2.

TABLE 2

RUN TOTAL REACTOR VVH NUMBER TINE TEMPERATURE ON STREAM A- hrs OC hr~l 1 19 165 1.90 2 43 165 1.50 3 114 170 1.48 4 142 170 1.49 5 162 170 1.48 6 186 170 1.47 7 210 170 1.47 8 281 170 1.45 9 330 170 1.45 10 378 170 1.44 11 449 175 1.47 12 473 175 2.17 The carbon number distributions and wt% paraffins in Table 3 below show that the hydrocarbon make-up of the feedstock was substantially unaffected using the specified catalyst, results confirmed by the distillation pattern shown in Table 4.

TABLE 3 CARBON NUMBER DISTRIBUTIONS FOR HEXENE FEED AND DESULPHURIZED PRODUCTS

CARBON NUMBER NUMBER FEED A-3 A-8 A-9 A-10 A-Il wt% < C5 0.12 0.18 0.04 0.03 0.04 0.04 C6 83.95 83.40 83.83 85.73 85.33 83.23 C7 15.23 15.57 15.22 13.40 13.76 15.60 C8 - - - - - Cg 0.02 0.02 0.01 0.01 0.01 0.02 Clo 0.14 0.14 0.14 0.13 0.14 0.15 C11 0.18 0.17 0.17 0.15 0.16 0.17 C12 0.37 0.43 0.50 0.47 0.48 0.66 C13 0.07 0.08 0.09 0.08 0.08 0.11 C14 0.01 0.01 - - - wt t paraffin 9.85 9.98 9.95 9.82 9.86 9.89 Temperature Reactor C - 170 170 170 170 175 vvHhr-1 - 1.48 1.45 1.45 1.44 1.47 TABLE 4 ASIM DISTILLATION (D-1078) FOR HEXNE FEED AND PRaYXnS

ASTM DISTIIIA- FEED TION, C A-3 A-8 A-9 A-10 A-il IBP 66.4 65.7 65.9 66.0 66.1 66.0 25 % 67.8 67.5 67.6 67.7 67.6 67.5 50 % 68.4 68.2 68.3 68.3 68.2 68.2 75 % 69.4 69.3 69.3 69.3 69.4 69.3 95 % 72.8 73.5 73.1 73.0 73.6 72.7 DP 73.8 74.5 74.5 74.5 74.5 74.9 EXAMPLE 1 The procedure of Example A was repeated, except that the hydrofinishing catalyst was spent hydro-finishing Girdler G-49 RS (initial analysis: 46% Ni; 9.0% Si; 0.6% Al; 0.3% Ca; 0.2% Fe) and the sulphur content of the feed was 180 ppm.Results are shown in Tables 5 and 6.

TABLE 5

RUN TOTAL REACTOR VVH NUMBER RUNTIME TEMPERATURE 1- hrs C hr-1 1 24 170 - 1.83 2 48 170 1.63 3 71 167 1.74 4 139 175 1.69 5 187 175 1.69 6 239 180 1.75 7 305 185 1.77 TABLE 6 CARBON NUMBER DISTRIBUTION FOR HEXENE FEED AND PRODUCTS

CAXN NUMBER FEED RUN 2-5 RUN 2-6 RUN 2-7 wt % C5 0.3 0.3 0.4 0.3 C6 87.4 85.7 85.4 84.9 C7 11.5 12.2 12.1 12.3 C8 - - - Cs - - C10 0.1 0.1 0.1 0.1 C11 0.3 0.3 0.2 0.3 C12 0.3 1.3 1.6 1.9 C13 0.1 0.1 0.2 0.2 C14 - - Temperature - 175 180 185 Reactor C VUH hr -1 - 1.69 1.75 1.77 EXAMPLE 2 The procedure of Example A was followed, but using fresh Girdler Catalyst G-134 A RS (analysis: 48% Ni; 6.8% Si; 6.8% Al; 0.3% Ca; 0.2% Fe).As Tables 7 and 8 show, an increase in temperature from 1800C to 1850C gave increased dimerization. It is also possible that there is an induction period with this catalyst, during which the surface oxide layer on the fresh material is reduced to nickel metal or converted to nickel sulphide.

TABLE 7

RUN TOTAL REACTOR VVH NUMBER TIME ON TEMPERATURE STREAM 2- hrs OC hr'l 5 164 180 1.39 6 188 180 1.37 7 212 180 1.36 8 237 185 1.41 9 308 185 1.43 TABLE 8 CARBON NUMBER DISTRI CARBON NUMBER DISTRIBUTION FOR HEXENE FEED AND PRODUCTS

CARBON NUMBER FEED RUN 2-6 RUN 2-7 RUN 2-8 RUN 2-9 wt % S Cg 0.3 0.7 0.5 0.6 0.5 C6 87.4 84.6 84.4 83.2 81.4 C7 11.5 12.2 12.0 12.0 12.1 C8 - - - - - Cs - - - - Clo 0.1 0.1 0.1 0.1 0.1 C11 0.3 0.4 0.4 0.4 0.4 C12 0.3 1.8 2.3 3.4 1 4.9 C13 0.1 0.2 0.2 0.3 0.5 C14 - - - - - wt 96 paraffin 21.6 22.5 22.1 22.2 21.4 Temperature - 180 180 185 185 Reactor C VVH hr -l i 1.37 1.36 1.41 1.43 Comparison Example B Following the procedure of Example A, fresh Harshaw Ni-3288 catalyst is charged to the reactor. The catalyst contains 60% nickel, 4% aluminium, 3.5% silicon, 1.8% calcium, and 0.2% iron. A sulphur bearing hexene feed was passed over the catalyst for a period of 900 hours, the temperature being raised at 5 C intervals from 1700C to 1850C during this period. Dimer formation was negligible.

In a second experiment, spent Ni-3288 catalyst was employed. An operating temperature of 1800C to 1850C was used; dimer formation was again negligible.

Example 3 The procedure of Example A was followed, but using fresh Girdler G-49 RS catalyst. The results are as shown in Tables 9, 10 and 11.

TABLE 9

RUN TOTAL REACTOR VVH NUMBER RUN TIME TEMPERATURE 3- hrs C hr-l 1 22 170 1.74 2 94 175 1.70 3 118 175 1.69 4 142 180 1.76 5 166 180 1.78 6 6 190 185 1.79 7 261 185 1.81 TABLE 10 CARBON NUMBER DISTRIBUTIONS FOR HEXENE FEED AND PRODUCTS

RUN CARBON NUMBER FEED 3-1 3-2 3-3 3-4 3-5 3-6 3-7 wt% < C5 0.3 0.9 0.9 1.2 0.9 0.8 0.7 0.7 C6 87.4 70.6 70.1 70.4 69.0 69.1 66.3 66.9 C7 11.5 11.7 12.2 11.8 12.1 12.3 12.2 12.1 C8 - 0.2 0.2 0.2 0.3 0.3 0.3 0.3 Cs - 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Clo 0.1 0.6 0.4 0.4 0.4 0.4 0.5 0.5 C11 0.3 1.9 1.4 1.3 1.3 1 1.3 1.7 1.6 C12 0.3 10.6 ; 11.7 11.9 13.1 12.9 14.3 14.2 C13 0.1 2.4 2.4 2.3 2.5 2.5 3.1 3.0 C14 - 1.0 0.6 0.4 0.3 0.3 0.9 0.6 wt % paraffin 21.6 19.4 18.9 18.5 18.6 18.1 19.1 19.2 BB ae Reactor OC - 170 175 175 180 180 185 185 hr-1 - 1.74 1.70 1.69 1.76 1.78 1.79 1.81 Delta wt % C12 + C13 - 12.6 13.7 13.8 15.2 15.0 17.0 16.8 TABLE 11 ASTM DISTILLATION (D-1078) FOR HEXENE FEED AND PRODUCTS

RUN ASTM FEED 3-l 3-4 3-7 DISTILLATION RESULTS C IBP 65.8 63.2 64.3 63.9 25% 67.9 67.0 67.3 67.2 50% 68.5 68.2 68.8 68.8 75% 71.2 73.5 77.4 76.4 95% 72.9 204.0 201.7 204.6 DP 74.8 204.6 202.0 205.4

Claims (20)

Claims:

1. A process for the oligomerization of an olefinic hydrocarbon which comprises subjecting the hydrocarbon to oligomerization conditions in the presence of a nickel catalyst on a porous support, the catalyst containing at least 35% by weight nickel, based on the total weight of the catalyst including support, the support comprising silicon and optionally calcium, the weight ratio of silicon to calcium if present being at least 8:1, and re-covering the resulting oligomer.

2. A process as claimed in claim 1, wherein the catalyst silicon:calcium weight ratio is at least 10:1.

3. A process as claimed in claim 1, wherein the catalyst silicon:calcium weight ratio is at least 20:1.

4. A process as claimed in any one of claims 1 to 3, wherein the catalyst silicon:calcium weight ratio is about 30:1.

5. A process as claimed in any one of claims 1 to 3, wherein the catalyst contains at most 1% by weight of calcium.

6. A process as claimed in any one of claims 1 to 3, wherein the catalyst is substantially calciumfree.

7. A process in any one of claims 1 to 6, wherein the catalyst contains at least 5% of silicon by weight.

8. A process in any one of claims 1 to 6, wherein the catalyst contains from 6 to 12% by weight of silicon.

9. A process as claimed in any one of claims 1 to 8, wherein the catalyst contains at least 40% by weight of nickel.

10. A process as claimed in claim 9, wherein the catalyst contains from 45 to 65% by weight of nickel.

11. A process as claimed in any one of claims 1 to 10, wherein the olefinic hydrocarbon comprises sulphur-containing impurities.

12. A process as claimed in any one of claims 1 to 11, wherein the olefinic hydrocarbon is a feedstock comprising C3 to C18 olefins.

13. A process as claimed in any one of claims 1 to 11, wherein the olefinic hydrocarbon is a pentene or a hexene.

14. A process as claimed in any one of claims 1 to 13, which is a dimerization process.

15. A process as claimed in claim 1, conducted substantially as described in any one of the numbered examples herein.

16. The use of a catalyst as defined in any one of claims 1 to 10 as a catalyst in the oligomerization of olefinic hydrocarbons.

17. The use as claimed in claim 16, wherein the catalyst is a spent catalyst.

18. The use as claimed in claim 16 or claim 17, wherein the olefinic hydrocarbon comprises sulphurcontaining contaminants.

19. Oligomers, whenever produced by the process of any of claims 1 to 15.

20. Any new feature hereinbefore described or any new combination of hereinbefore described features.