Process for producing cumene and/or sec-butylbenzene using a mixed olefins stream as alkylation agent

Abstract

The present invention relates to a process for producing cumene and/or sec-butylbenzene comprising contacting benzene with a mixed olefins stream comprising ethylene and an alkylation agent in the presence of a selective alkylation catalyst under selective alkylation conditions.

Claims

1. A process for producing cumene and/or sec-butylbenzene, the process comprising contacting benzene with a mixed olefins stream comprising ethylene and an alkylation agent in the presence of a selective alkylation catalyst under selective alkylation conditions, wherein the alkylation agent is propylene and/or butylene, wherein said selective alkylation catalyst comprises a zeolite having a 12-membered ring structure and a 3D cage structure, wherein the selective alkylation conditions comprise a weight hourly space velocity of at least 10 h.sup.1, a pressure of 1000-5000 kPa and a temperature of 100-250 C., wherein there is a stoichiometric excess of benzene relative to olefins, and wherein the ethylbenzene yield of the process is less than 0.2%.

2. The process according to claim 1, wherein the zeolite further has a pore size of 6.4-8.5 .

3. The process according to claim 1, wherein the mixed olefins stream is produced by a process selected from the group consisting of catalytic cracking, steam cracking, and syngas-to-olefins process.

4. The process according to claim 1, further comprising separating the cumene and/or sec-butylbenzene and subjecting the cumene and/or sec-butylbenzene to oxidation and subsequent cleavage to produce phenol and ketone.

5. The process according claim 4, wherein said separating the cumene and/or sec-butylbenzene comprises a gas-liquid separation to separate a gaseous stream comprising C1-C4 hydrocarbons and hydrogen from the cumene and/or sec-butylbenzene.

6. The process according to claim 4, wherein said separating the cumene and/or sec-butylbenzene comprises a distillation step to separate the C6+ hydrocarbons and wherein the thus obtained C6+ hydrocarbons are subjected to distillation to separate the cumene and/or sec-butylbenzene.

7. The process according to claim 6, wherein the distillation to separate the C6+ hydrocarbons further provides a C6 stream, wherein the thus obtained C6 stream is recycled to the alkylation.

8. The process according to claim 6, wherein the distillation of C6+ hydrocarbons further provides a stream comprising heavies, wherein the thus obtained heavies are recycled to the catalytic cracking.

9. The process according to claim 5, wherein the gaseous stream obtained by the gas-liquid separation is contacted with benzene in the presence of an ethylene alkylation catalyst under ethylene alkylation conditions, wherein the alkylation agent is ethylene and wherein the ethylene alkylation catalyst comprises beta zeolite, zeolite Y, ZSM-12, MCM-22 and mordenite and the ethylene alkylation conditions comprise a temperature of 120-250 C., a pressure of 1000-5000 kPa gauge, a Weight Hourly Space Velocity (WHSV) of 0.5-20 h.sup.1, and a benzene/ethylene molar ratio of 2-10.

10. The process according to claim 9, wherein the product produced by ethylene alkylation is subjected to gas-liquid separation to separate a gaseous stream comprising C1-C4 alkanes and hydrogen.

11. The process according to claim 10, wherein the liquid stream provided by the gas-liquid separation of the product produced by ethylene alkylation is subjected to distillation to provide ethylbenzene.

12. The process according to claim 4, wherein the cumene and sec-butylbenzene oxidation and subsequent cleavage comprises an oxidation step comprising contacting the cumene and/or sec-butylbenzene with an oxidation catalyst and air under oxidation conditions to produce sec-butylbenzene hydroperoxide and/or cumene hydroperoxide and a cleavage step comprising contacting the sec-butylbenzene hydroperoxide and/or cumene hydroperoxide with a cleavage catalyst under cleavage conditions to produce phenol and/or ketone, wherein said oxidation catalyst comprises a transition metal and the oxidation conditions comprise a temperature of 50-150 C., and a pressure of atmospheric to 1000 kPa and wherein said cleavage catalyst is a homogeneous or heterogeneous acid catalyst and the cleavage conditions comprise a temperature of 40-120 C., a pressure of atmospheric to 1000 kPa gauge and a LHSV between 1-50 h.sup.1.

13. The process according to claim 9, wherein the ethylene alkylation conditions comprise a temperature of 200-240 C., a pressure of 2000-3000 kPa gauge, a Weight Hourly Space Velocity (WHSV) of 1-10 h.sup.1 and a benzene/ethylene molar ratio of 3-6.

14. The process according to claim 1, wherein the zeolite is a Y zeolite.

15. The process according to claim 1, wherein a partial pressure of ethylene is 400-700 kPa.

16. The process according to claim 15, further comprising a propylene partial pressure of 100-200 kPa.

Description

(1) The present invention will now be more fully described by the following non-limiting Examples.

(2) FIG. 1 shows the conversion and product selectivities of the selective alkylation process of the present invention using a beta zeolite-based catalyst.

(3) FIG. 2 shows the conversion and product selectivities of the selective alkylation process of the present invention using a zeolite Y-based catalyst.

EXAMPLE 1

(4) Selective Alkylation

(5) Mixed olefin feed was obtained by mixing 30 wt % ethylene and 10 wt % propylene with 60 wt % of nitrogen. Similarly, synthetic C6 heart cut composition was obtained by mixing 50 wt % Benzene with other C6 paraffins such as iso-hexane (34 wt %), n-hexane (13 wt) and cyclo-hexane (3 wt %).

(6) Alkylation catalysts were obtained as follows. Beta zeolite with Si/Al ratio of 19 and surface area of 710 m.sup.2/g in NH.sub.4 form was first calcined in air at 100 C. for three hours then heated to 300 C. for three hours with ramp rates of 3 C./min to remove ammonia and to obtain beta zeolite in the hydrogen form. Further, Y zeolite based catalyst having a Si/Al ratio of 2.6 and a surface area of and 660 m.sup.2/g in the hydrogen form was used. Both beta zeolite and Y zeolite were sized by pressing in a die to 69 MPa (10,000 psi) then breaking up the wafer and sieving the catalyst particles to obtain the desired particle size of 125-160 m.

(7) Alkylation of synthetic C6 heart cut with mixed olefin feed having the above-indicated composition was carried out in high throughput micro catalytic reactor with an internal diameter of 3.5 mm with isothermal heating zone length of 14 cm. In this study, nine parallel micro catalytic reactors were used, wherein the first four reactor were filled with the above-described beta zeolite catalyst with different mass of catalyst to maintain the WHSV of 2, 4, 10 and 2 h.sup.1. A second set of four parallel reactors were filled with the above described Y zeolite catalyst with different mass of catalyst to also maintain a WHSV of 2, 4, 10 & 2 h.sup.1. The ninth reactor was filled with inert quartz particles to check any reactivity in absence of catalyst activity.

(8) FIGS. 1 and 2 show the result of the alkylation experiments at the temperature of 200 C., partial pressure of ethylene & propylene 570 and 130 kPa, respectively and benzene/olefins ratio of 4 with varying WHSV from 2 to 10 h.sup.1. From these experiments, it is very clear that conversion of propylene is 100% irrespective of catalyst and other parameters. Similarly, complete conversion of ethylene is noticed with both Y Zeolite with WHSV of 2 h.sup.1 and Beta zeolite with WHSV 2 & 4 h.sup.1. In all cases product selectivity towards ethylbenzene was 75% and cumene 90% and the main by-products were di-ethylbenzenes and di-isopropylbenzenes. Surprisingly, Y zeolite catalyst at a space velocity of WHSV 10 h.sup.1 or more shows very negligible in ethylene conversion of (0.2%), particularly when compared with beta zeolite catalyst.

(9) The above experiment clearly demonstrate that WHSV is playing major role for selective alkylation of benzene with propylene in presence of ethylene. In addition, selective alkylation is also affected by nature of catalyst. Compared to beta zeolite catalyst, Y zeolite catalyst at 180 to 200 C., a partial pressure of ethylene & propylene 570 and 130 kPa, respectively, and a benzene/olefins ratio of 4, is showing best result for selectively alkylate benzene with propylene at WHSV of 10 h.sup.1.

(10) The other C6 component (iso-hexane, n-hexane and cyclo-hexane) present in the diluted benzene feed conversion was also calculated in the same experimental conditions for the beta zeolite catalyst and the Y zeolite catalyst. Here, it was found that co-feed conversion of the n-hexane, cyclohexane and isohexanes is very limited (<1%) at T=180-200 C. for beta zeolite catalyst and Y zeolite catalyst. In the case of Y zeolite catalyst with WHSV 2 h.sup.1 shows little higher conversion of 5% for iso-hexane at 200 C.

(11) In the context of the present invention, the equations used to calculate conversion, selectivity and WHSV were calculated as describe in the following Table 1

(12) TABLE-US-00001 TABLE 1 $\mathrm{Conversion}\mathrm{of}\mathrm{benzene}=\frac{{\mathrm{Benzene}}_{\left(\mathrm{in}\right)}-{\mathrm{Benzene}}_{\left(\mathrm{out}\right)}}{{\mathrm{Benzene}}_{\left(\mathrm{in}\right)}}$ $\mathrm{Conversion}\mathrm{of}\mathrm{Ethylene}=\frac{{\mathrm{Ethylene}}_{\left(\mathrm{in}\right)}-{\mathrm{Ethylene}}_{\left(\mathrm{out}\right)}}{{\mathrm{Ethylene}}_{\left(in\right)}}$ $\mathrm{Conversion}\mathrm{of}\mathrm{Propylene}=\frac{{\mathrm{Propylene}}_{\left(\mathrm{in}\right)}-{\mathrm{Propylene}}_{\left(\mathrm{out}\right)}}{{\mathrm{Propylene}}_{\left(\mathrm{in}\right)}}$ $\mathrm{Selectivity}\mathrm{of}\mathrm{Ethyl}\mathrm{benzene}\left(\mathrm{Yi}\right)=\frac{\mathrm{Ethyl}\mathrm{benzene}\left(\mathrm{Yi}\right)}{\mathrm{Total}\mathrm{aromatics}}$ $\begin{array}{c}\mathrm{Weight}\mathrm{Hour}\mathrm{Space}\mathrm{Velocity}\\ \left(\mathrm{WHSV}\right)\end{array}=\frac{{\mathrm{Benzene}}_{\left(\mathrm{in}\right)}-{\mathrm{Benzene}}_{\left(\mathrm{out}\right)}}{\mathrm{Catalyst}\mathrm{weight}}$

EXAMPLE 2

Comparative

(13) Alkylation experiment was also performed with the above-mentioned feed and conditions with zeolite ZSM-5 having Si/Al ratio of 80 & 280 and Mordenite. It is observed that the conversion of benzene and olefins (ethylene and propylene) is not appreciable compared to Beta and Y zeolite and not suitable for selective alkylation.

(14) The alkylation catalysts as used in Examples 1 and 2 are further described in the following Table 2

(15) TABLE-US-00002 TABLE 2 Beta Mordenite Zeolite Y ZSM-5 ZSM-5 Si/Al (mol 38 13 5.2 80 280 ratio) Area (m.sup.2/g) 710 425 660 425 425 Cage 3D 1D 3D 3D 3D Structure Pore Size 7.6 6.4 6.5 7.0 7.4 5.4 5.6 5.4 5.6 () Ring 12 12 12 10 10 structure type