CATALYST LOADING METHOD TO DISPERSE HEAT IN HYDROCONVERSION REACTOR

Abstract

The invention relates to a method for modulating and controlling heat produced during an exothermic catalytic reaction. By combining two or more catalysts with differing activation energies, one can control the amount of heat change produced while the action proceeds. Among the advantages of such a process is the control of temperatures so that the change is within reactor tolerance.

Claims

1. A method for dispersing heat generated by a catalytic reaction comprising, combining at least two catalyst which have different activity temperatures and same functions in a catalysts being combines in a ratio sufficient to maintain an end of run temperature below a tolerance temperature of said reactor.

2. The method of claim 1, comprising admixing said at least two catalysts to form a uniform composition.

3. The method of claim 1, comprising providing a plurality of individual layers of said at least two catalysts in said catalytic reactor.

4. The method of claim 1, wherein said at least two catalysts are hydrocracking catalysts.

5. The method of claim 1, wherein at least one of said catalysts is an amorphous based catalyst, and at least one of said catalysts is a zeolite based catalyst.

6. The method of claim 5, wherein said amorphous based catalyst contains Ni and Mo or Ni and W.

7. The method of claim 1, wherein at least one of said at least two catalysts contains Co and Mo, Ni, and Mo, or Pt and Pd.

8. The method of claim 1, wherein said at least two catalysts are present in a range from 1/99 to 99/1 ratio.

9. The method of claim 8, wherein said at least two catalysts are an amorphous catalyst and a zeolite catalyst. The method of claim 1, wherein said catalytic reactor has a tolerance of from 25? C. to 40? C. higher than said activity temperature for one of said at least two catalysts having highest activity temperature of said at least two catalysts.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] FIG. 1 shows a typical system of catalysts and reactors known to the art.

[0041] FIG. 2 shows a catalyst and reactor system in accordance with the invention where then layers of two catalysts are used while two are shown, more than two are possible.

[0042] FIG. 3 depicts an embodiment of the invention where the catalysts are mixed to form a uniform combination of two or more catalysts, while two are shown, more than two are possible.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0043] As noted, supra, the prior art shows the use of single catalysts, in reactor beds separated by quencher zones (FIG. 1). FIG. 2 shows a reactor 201, lacking quencher zones, in which alternating layers of catalysts are placed. These can be a zeolite catalyst and an amorphous catalyst (202 and 203), as described supra, or can include more than two catalysts, i.e., more than one amorphous catalyst, or more than one zeolite catalyst, or more than one of both.

[0044] In FIG. 3, reactor 301 contains a uniform mixture of the catalysts 202 and 203, discussed supra. As with the embodiment of FIG. 2, more than two different catalyst may be used.

Example 1

[0045] A feedstock blend is hydrocracked in a first stage of a hydrocracker unit. The feedstock contained 15 V % demetalized oil (DMO), and 85 V % vacuum gas oil (VGO) of which 64% is heavy VGO (HVGO) and 21% is light VGO (LVGO). The feedstock had a specific gravity of 0.918 contained 2.2 wt % of sulfur, 751 ppmw nitrogen, and had a bromine number of 3.0 g/100 g feedstock. Other properties included 12.02 wt % hydrogen, an IBP (initial boiling point) of 210? C., a 10/30 of 344/411? C., a 50/70 of 451/498? C., a 90/95 of 595/655? C., and a 98 of 719? C.

[0046] The simulations were carried-out using in-house kinetic models, which were based on extensive pilot plant data spanning 440 days of operations. An amorphous catalyst was used in the process and the hydrogen partial pressure, LHSV are set at 115 bars 0.435 h.sup.?1, respectively. In the simulations, the maximum delta T was set at 40? C. and the resultant conversion level and the required operating temperature are calculated. As seen, the temperature at the top bed is 396 and the bottom of the bed is 436? C. So with the amorphous catalyst the start-of-run (SOR) temperature at the top bed is 396? C. is needed to achieve the 47.2 V % conversion, which is close to the targeted 50 V % conversion.

[0047] The simulation reveals that a high operating temperature was necessary to achieve 47.1 V % conversion, which is close to 50 V %, within the acceptable delta temperature across the bed.

TABLE-US-00001 Temperature Conversion Delta T Cumulative Bed# ? C. W % ? C. 1Top 395 2.7 2.4 1Bot-2Top 399 3.0 5.0 2Bot-3Top 401 3.4 8.0 3Bot-4Top 404 3.9 11.4 4Bot-5Top 408 4.6 15.3 5Bot-6Top 412 5.5 20.0 6Bot-7Top 416 6.7 25.7 7Bot-8Top 422 8.6 32.8 8Bot-9Top 429 11.5 42.2 9Bot 438 47.1 39.9

Example 2

[0048] The simulation was repeated using a zeolite catalyst. The results which follow, show that a 49.6% conversion (very close to desired 50%), was achieved at a temperature of 375? C. at the top of the bed and 415? C. at the bottoms of the bed, significantly less than the 438? C. for the amorphous catalyst.

[0049] Similarly, the maximum delta T was set at 40? C. with the zeolitic catalysts. As seen, the SOR temperature at the top bed is 375? C. and the bottom of the bed is 415? C. So with the zeolitic catalyst the temperature requirement decreased substantially (21? C. less) to achieve the 49.6 V % conversion which is very close to 50 V % target. The heat can be managed as the SOR temperature is low. However, this catalyst is very sensitive to temperature changes as its activation energy is high, i.e., >50 Kcal/mol. Any slight increase in temperature will result in high heat release and the delta temperature across the reactor will exceed the maximum 40? C. limit. So this catalyst will not be recommended for this operation.

TABLE-US-00002 Temperature Conversion, Delta T Cumulative Bed# ? C. W % ? C. 1Top 375 1.5 1.3 1Bot-2Top 376 1.7 2.8 2Bot-3Top 378 2.0 4.6 3Bot-4Top 380 2.4 6.7 4Bot-5Top 382 3.0 9.3 5Bot-6Top 384 4.0 12.7 6Bot-7Top 388 5.7 17.6 7Bot-8Top 393 9.2 25.2 8Bot-9Top 400 19.0 40.0 9Bot 415 40.0 48.6

Example 3

[0050] In this example, a 50/50 blend of the amorphous and zeolite catalysts of the first two examples was used. Again, the conditions of Example 1 were used. The results show a temperature increase of 10? C. at the top of the bed versus the zeolite (375? C. vs. 385? C.), and a 10? C. increase at the bottom of the bed (415? C. versus 425? C.), to achieve a 47.5% conversion.

[0051] Similarly, the maximum delta T was set at 40? C. with the zeolitic/amorphous catalysts. As seen, the temperature at the top bed is 385? C. and the bottom of the bed is 425? C. So with the blend catalysts system the temperature requirement increased by 10? C. to achieve the 48.6 V % conversion which is very close to 50 V % target compared to the pure zeolitic system and the heat in the reactor can be managed:

TABLE-US-00003 Temperature Conversion Delta T Cumulative Bed# ? C. W % ? C. 1Top 385 2.2 1.9 1Bot-2Top 387 2.5 4.1 2Bot-3Top 389 2.8 6.5 3Bot-4Top 392 3.3 9.3 4Bot-5Top 395 3.9 12.7 5Bot-6Top 398 4.9 16.9 6Bot-7Top 402 6.3 22.2 7Bot-8Top 408 8.7 29.5 8Bot-9Top 415 13.0 40.0 9Bot 425 40.0 47.5 40

[0052] This clearly shows that the zeolitic catalysts are much more active than the amorphous catalysts and the heat generated from a blended catalyst system can be managed easily.

Example 4

[0053] Finally, a system using a stacked bed of amorphous/zeolite was used, rather than a mix.

[0054] The results follow, and show a necessary starting temperature of 377? C., very close to the pure zeolite system, and an ending temperature of 417? C., to 48.8 W % of the feedstock.

[0055] These results also show that most of the conversion takes place with the zeolite catalyst.

[0056] Similarly, the maximum delta T was set at 40? C. with the zeolitic/amorphous stacked bed catalysts (50:50 V %). As seen, the temperature at the top bed is 377? C. and the bottom of the bed is 417? C. So with the stacked bed catalysts system the temperature requirement is close to the zeolitic system to keep the delta temperature at max level, 40? C. to achieve the 48.6 V % conversion which is very close to 50 V % target compared to the pure zeolitic system. As seen, the amorphous catalyst system is underutilized as most of the conversion is taking place on the zeolitic catalysts. If both catalysts need to be utilized to benefit from both catalysts, different reactors must be used and run at different temperatures: 1.sup.st reactor with amorphous catalysts operating at higher temperature and 2.sup.nd reactor operating at lower temperature, which means 1.sup.st reactor effluents must be cooled down.

TABLE-US-00004 Temperature Conversion Bed# ? C. W % Delta T Cumulative 1Top 377 1.2 1.1 1Bot-2Top 378 1.3 2.2 2Bot-3Top 379 1.4 3.5 3Bot-4Top 381 1.5 4.8 4Bot-5Top 382 1.6 6.1 5Bot-6Top 383 4.2 9.7 6Bot-7Top 387 6.0 14.8 7Bot-8Top 392 10.0 23.1 8Bot-9Top 400 21.7 39.6 9Bot 417 39.6 48.8

[0057] What the results show in addition to the data tables presented, if one seeks the benefits of both catalysts, different reactors are needed, because the very high temperatures needed for the amorphous catalyst, require quenching or cooling of the products before they are applied to the zeolite catalyst.

[0058] Other features of the invention will be clear to the skilled artisan and need not be reiterated here.

[0059] The terms and expression which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expression of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.