PROCESS FOR PRODUCING MONOAROMATIC HYDROCARBONS FROM A HYDROCARBON FEED COMPRISING POLYAROMATICS

Abstract

The present invention relates to a process for producing monoaromatic hydrocarbons from a hydrocarbon feed comprising polyaromatics, the process comprising contacting the feed at process conditions with a catalyst comprising a mixture of zeolite Y and a hydrogenation catalyst comprising one or more hydrogenation metals on a solid catalyst support.

Claims

1. A process for producing monoaromatic hydrocarbons from a hydrocarbon feed comprising polyaromatics, the process comprising: contacting the feed at process conditions comprising a temperature of 350-550 C., a pressure of 2000-7000 kPa, a WHSV of 0.1-10 h.sup.1 and a H.sub.2/HC molar ratio of 3-12, with a catalyst comprising a mixture of zeolite Y having a SiO.sub.2/Al.sub.2O.sub.3 ratio of 10-80 and a hydrogenation catalyst comprising a hydrogenation metal on a solid catalyst support, wherein said hydrogenation catalyst is selected from the group consisting of: a catalyst comprising: 1-30 wt-% of Mo and/or W, based on the total weight of the hydrogenation catalyst and, 0.1-10 wt-% of Co and/or Ni, based on the total weight of the hydrogenation catalyst; and a catalyst comprising 0.05-2 wt-% of an element selected from Groups 8-10 of the Periodic Table of Elements, based on the total weight of the hydrogenation catalyst.

2. The process according to claim 1, wherein the process conditions comprise a temperature of 400-475 C.

3. The process according to claim 1, wherein the zeolite Y has a SiO.sub.2/Al.sub.2O.sub.3 ratio of 10-40, and the process conditions comprise a pressure of 2000-7000 kPa.

4. The process according to claim 1, wherein the zeolite Y has a SiO.sub.2/Al.sub.2O.sub.3 ratio of 40-80, the hydrogenation catalyst comprises 0.05-2 wt-% based on the total weight of the hydrogenation catalyst of one or more elements selected from Groups 8-10 of the Periodic Table of Elements and the process conditions comprise a pressure of 4000-7000 kPa.

5. The process according to claim 1, wherein the hydrogenation catalyst comprises 3-20 wt-% of Mo and/or W based on the total weight of the hydrogenation catalyst and 0.7-7 wt-% of Co and/or Ni based on the total weight of the hydrogenation catalyst.

6. The process according to claim 1, wherein the hydrogenation catalyst comprises one or more selected from the group consisting of: Co and Mo; Ni and Mo; Ni and W; and Co and W.

7. The process according to claim 1, wherein the hydrogenation catalyst comprises Mo and/or W and Co and/or Ni in sulfide form.

8. The process according to claim 1, wherein the hydrogenation catalyst comprises 0.1-1.25 wt-% based on the total weight of the hydrogenation catalyst of an element selected from Groups 8-10 of the Periodic Table of Elements.

9. The process according to claim 1, wherein the element is Pd and/or Pt.

10. The process according to claim 1, wherein the zeolite Y comprises super cages having a size of 12-14 .

11. The process according to claim 1, wherein the heavy hydrocarbon feed comprises at least 30 wt-% polyaromatics.

12. The process according to claim 1, wherein the heavy hydrocarbon feed comprises at most 200 wppm sulfur.

13. The process according to claim 1, wherein the hydrocarbon feed is selected from the group consisting of heavy cycle oil, light cycle oil, carbon black oil, cracked distillate and pyoil.

14. The process according to any one of claim 8, wherein the element is Pd and/or Pt.

15. A process for producing monoaromatic hydrocarbons from a hydrocarbon feed comprising polyaromatics, the process comprising: contacting the feed at process conditions comprising a temperature of 400-475 C., a pressure of 2000-7000 kPa, a WHSV of 0.1-10 h.sup.1 and a H.sub.2/HC molar ratio of 3-12, with a catalyst comprising a mixture of zeolite Y having a SiO.sub.2/Al.sub.2O.sub.3 ratio of 10-40 and a hydrogenation catalyst comprising a hydrogenation metal on a solid catalyst support, wherein said hydrogenation catalyst is selected from the group consisting of: a catalyst comprising: 1-30 wt-% of Mo and/or W, based on the total weight of the hydrogenation catalyst and, 0.1-10 wt-% of Co and/or Ni, based on the total weight of the hydrogenation catalyst.

16. The process according to claim 15, wherein the hydrogenation catalyst comprises 3-20 wt of the Mo and/or the W, and 0.7-7 wt-% of the Co and/or the Ni, based on the total weight of the hydrogenation catalyst.

17. The process according to claim 16, wherein the hydrogenation catalyst comprises one or more selected from the group consisting of: Co and Mo; Ni and Mo; Ni and W; and Co and W.

18. A process for producing monoaromatic hydrocarbons from a hydrocarbon feed comprising polyaromatics, the process comprising: contacting the feed at process conditions comprising a temperature of 400-475 C., a pressure of 4000-7000 kPa, a WHSV of 0.1-10 h.sup.1 and a H.sub.2/HC molar ratio of 3-12, with a catalyst comprising a mixture of zeolite Y having a SiO.sub.2/Al.sub.2O.sub.3 ratio of 40-80 and a hydrogenation catalyst comprising a hydrogenation metal on a solid catalyst support, wherein said hydrogenation catalyst is selected from the group consisting of: a catalyst comprising 0.05-2 wt-% of an element selected from Groups 8-10 of the Periodic Table of Elements, based on the total weight of the hydrogenation catalyst, wherein the zeolite Y has a SiO.sub.2/Al.sub.2O.sub.3 ratio of 40-80.

19. The process according to claim 18, wherein the hydrogenation catalyst comprises 0.1-1.25 wt-% Pd and/or Pt.

Description

EXAMPLE

Catalyst Preparation

Physical Mixture Catalyst:

[0035] All catalyst mixtures are based on a 1:1 or a 1:2 weight ratio of the hydrogenation catalyst and the zeolite Y. Particle size of all catalysts was in the order of 100 to 150 m and obtained by ball milling and sieving. As the zeolite was available as a powder it first had to be bounded with alumina to increase the particle size. This was done by using Disperal. The procedure is as follows: Zeolite, Disperal and water are mixed in 7:3:40 weight ratio respectively. The slurry is then ball milled for 15 minutes at 600 rpm with balls of 1.3 mm diameter. After milling the slurry is dried at 120 C. in an open beaker after which the particles are transferred into a hotbox for overnight drying at 110 C. The next day the material was calcined at 300 C. for 6 hours.

Experimental Set-Up

[0036] The loading of catalysts into the reactor was done carefully in order to obtain a homogeneous mixture. The following catalysts were used: hydrogenation catalyst: UOP R12 (commercially available) and zeolite Y: Zeolyst CBV780 and CBV712 (both commercially available).

Catalyst Activation:

[0037] All catalyst mixtures were activated in situ. First the reactor was purged with nitrogen up to 60 C. Then a flow of hydrogen was introduced and the reactor was heated at 1 C./min to a temperature of 400 C. This temperature was maintained for 2 hours before the reactor was allowed to cool in hydrogen flow.

[0038] Tests have been performed to process in a single step a di- and tri-aromatics containing hydrocarbon stream into mono-aromatics and LPG. To mimic Light Cycle Oil (LCO) a model feed was used with the composition given in Table 1. All experiments were performed with a 10 to 1 hydrogen to hydrocarbon molar ratio.

TABLE-US-00001 TABLE 1 Model feed composition details. Model Feed Decane 25 wt % Propylbenzene 20 wt % Naphthalene 25 wt % 1-Methylnaphthalene 15 wt % 2-Methylnaphthalene 10 wt % Anthracene 2 wt % Phenantrene 3 wt %

[0039] The model feed was exposed to different catalyst mixtures (UOP R12 and CBV712 with both 1:1 and 1:2 weight ratio, UOP R12 and CBV780 with 1:1 weight ratio) in a single fixed bed at 30, 60 and 100 bars and temperatures ranging from 250 to 450 C. in a 16 parallel reactor setup. FIG. 1 summarizes the results obtained for different catalyst systems, pressures and space velocities at temperatures of 350, 400 and 450 C. The plot shows the number of moles of mono-aromatics gained vs. the number of moles of ring opened di- and tri-aromatics. If the ratio of the two is 1:1 the mono-aromatics selectivity is 100%. That means that each multi ring component being ring opened results in the yield of a mono-aromatic component.

[0040] The results were calculated using the following formulas:

Monoaromatics gain=monoaromatics.sub.outmonoaromatics.sub.in

Ring openened di- and triaromatics=diaromatics.sub.in+triaromatics.sub.inany component consisting of 2 or more rings.sub.out

Ring opening conversion=(diaromatics.sub.in+triaromatics.sub.inany component consisting of 2 or more rings.sub.out)/(diaromatics.sub.in+triaromatics.sub.in)

Monoaromatics selectivity=monoaromatics gain/ring opened di- and triaromatics=(monoaromatics.sub.outmonoaromatics.sub.in)/(diaromatics.sub.in+triaromatics.sub.inany component consisting of 2 or more rings.sub.out)

[0041] The monoaromatics gain is defined as the amount of moles of monoaromatics in the reactor effluent minus the amount of moles of monoaromatics present in the feed per quantity of feed processed.

[0042] The amount of ring openened di- and tri-aromatics is defined as the amount in moles of di-aromatics and tri-aromatics present in the feed minus the total amount in moles of any component having two or more rings present in the effluent per quantity of feed processed.

[0043] The ring opening conversion is obtained by dividing the difference in moles of di-aromatics plus triaromatics present in the feed and the total amount in moles of any component having two or more rings present in the effluent, by the amount in moles of di-aromatics plus tri-aromatics present in the feed

[0044] Monoaromatics selectivity is defined as the monoaromatics gain (as defined before) divided by the amount of ring openened di- and triaromatics (as defined before)

[0045] FIG. 1 describes the mono-aromatics gain versus extent of ring opening for catalyst mixtures at three different temperatures. The plot on right is a zoom on the low conversion range. The data from the experiment at highest temperature (450 C.) gives the steepest slope indicating that the selectivity towards mono-aromatics is highest at this temperature.

TABLE-US-00002 TABLE 2 Ring opening conversion and mono-aromatics selectivity for various pressure/temperature combinations. For each condition the highest mono-aromatics gain (grey line) case was selected. Reaction Ring open Monoaromatics Monoaromatics conditions conversion (%) selectivity (mol %) gain (w %) 350 C., 30 bar 6.9 29.2 0.9 350 C., 60 bar 8.5 20.1 0.6 350 C., 100 bar 7.9 9.5 0.2 400 C., 30 bar 15.3 30.9 1.7 450 C., 30 bar 36.8 69.4 8.2 450 C., 60 bar 92.8 77.7 20.4 450 C., 100 bar 96.2 63.1 15.3

[0046] Table 2 gives an overview of the cases of highest mono-aromatics yield for each individual pressure/temperature combination tested. This means that results can be obtained with different catalysts and weight hourly space velocities. Activity increases with both an increase in temperature as an increase in pressure. However, higher pressures tend to cause a decrease in selectivity towards aromatics saturation. The optimum combination is found for the system tested at 60 bars and 450 C. which has the highest mono-aromatics yield: a gain of 20 w %.

TABLE-US-00003 TABLE 3 Ring opening conversion and mono-aromatics selectivity at 450 C. for two zeolite Y acidities and pressures of 60 and 30 bars. Used zeolite Si/Al.sub.2 ratio and Ring open Monoaromatics reaction pressure conversion (%) selectivity (mol %) Si/Al.sub.2 = 80, 60 bar 92.8 77.7 Si/Al.sub.2 = 12, 60 bar 72.9 77.1 Si/Al.sub.2 = 12, 60 bar 67.9 76.3 Si/Al.sub.2 = 80, 30 bar 36.8 69.4 Si/Al.sub.2 = 12, 30 bar 21.5 75.5 Si/Al.sub.2 = 12, 30 bar 18.2 73.0

[0047] Table 3 shows results on activity and selectivity when zeolites with two different SiO.sub.2/Al.sub.2O.sub.3 ratios are used. The effect on selectivity is only marginal whereas there is a clear activity advantage for catalyst mixtures using the zeolite Y with a SiO.sub.2/Al.sub.2O.sub.3 ratio of 80. Therefore, the use of this zeolite will result in the highest mono-aromatics yields.