Process for producing LPG from a heavy hydrocarbon feed

Abstract

A process comprising contacting said feed in the presence of hydrogen with a M/zeolite catalyst under hydrocracking process conditions.

Claims

1. A process for producing LPG from a hydrocarbon feed comprising polyaromatics, the process comprising contacting the feed in the presence of hydrogen with a M/zeolite catalyst at a pressure of 65-150 bara, a temperature of 350-500 C., a WHSV of 0.1-10 h.sup.1 wherein said M/zeolite catalyst comprises 0.05-2.5 wt-% of element M, wherein said element M is one or more elements selected from Group 10 of the Periodic Table of Elements; and an aluminosilicate zeolite having a pore size of 6-8 and a SiO.sub.2/Al.sub.2O.sub.3 ratio of 50-120.

2. The process according to claim 1, wherein the process conditions comprise a pressure of 70-120 bara.

3. The process according to claim 2, wherein the process conditions further comprise a temperature of 400-470 C.and a WHSV of 1-3 h.sup.1.

4. The process according to claim 1, wherein the M/zeolite catalyst comprises an aluminosilicate zeolite having a SiO.sub.2/Al.sub.2O.sub.3 ratio of 60-100.

5. The process according to claim 1, wherein the M/zeolite catalyst comprises 0.5-2 wt-% of element M.

6. The process according to claim 1, wherein element M is one or more elements selected from the group consisting of Pd and Pt.

7. The process according to claim 1, wherein the aluminosilicate zeolite has a 12-ring structure.

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

9. The process according to claim 8, wherein the aluminosilicate zeolite is zeolite Y.

10. The process according to claim 9, wherein the zeolite Y is partially dealuminated.

11. 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.

12. The process according to claim 1, wherein element M is Pt.

13. The process according to claim 12, wherein the hydrocarbon feed comprises at least 10 wt-% polyaromatics.

14. The process according to claim 13, wherein the aluminosilicate zeolite is zeolite Y.

15. The process according to claim 12, wherein the M/zeolite catalyst comprises 0.5-2 wt-% of Pt.

16. The process according to claim 1, wherein the hydrocarbon feed comprises at least 10 wt-% polyaromatics.

17. The process according to claim 1, wherein an amount of the LPG produced is at least 70 wt-% based on a total product.

18. The process according to claim 17, wherein an amount of methane produced is less than 1 wt-% based on a total product.

19. The process according to claim 1, wherein an amount of methane produced is less than 1 wt-% based on a total product.

Description

EXAMPLE

Catalyst Preparation

(1) Physical Mixture Catalyst:

(2) The physical mixtures of hydrogenation and solid acid catalysts are composed of commercially available catalyst samples. The hydrogenation catalyst is a Pt/Al.sub.2O.sub.3 from UOP, namely R-12. The zeolite is an unmodified zeolite Y from Zeolyst, namely CBV 780. These samples have been mixed in a 1 to 1 weight ratio.

(3) Bifunctional Pt/Zeolite Y Catalyst:

(4) 65 grams of Zeolyst CBV 780 are divided into 3 ceramic dishes and calcined in air at 100 C. for 3 hours to 300 C. and then to 550 C. for 10 hours using a ramp rate of 3 C./min.

(5) After calcination, 15 grams of pre-dried sample are dispersed in 1 liter of deionized water and stirred at 65 C. overnight. The next day the temperature is raised to 70 C. and a solution of 0.317 g of Pt(NH.sub.3).sub.4 (NO.sub.4).sub.2 is dissolved in 76.4 g of DI-H20 and added drop wise over a period of 7 hours. The material is allowed to stir overnight at 70 C. prior to filtering off the liquid. The filter cake is re-suspended in 1 liter of fresh DI-H20 and allowed to stir for 15 min and subsequently filtered again. The washing step is repeated twice more. The material is then allowed to dry overnight on filter paper at room temperature. Next, the material is dried at 80 C. for 3 hours, pressed (10,000 psi), crushed and sieved (35-60 mesh sizing scheme). The sized material is loaded in a tube furnace with an air flow rate of 2.2 L/min. The furnace is heated to 100 C. for 3 hours then to 300 C. for 3 hours at a ramp rate of 0.2 C./min. Subsequently, the material is further calcined to 350 C. at 0.2 C./min for 3 hours. The flows rates are then turned down to down to 1 L/min for 1 hour then to 345 ml/min for 1 hour while 350 C. is maintained. The material is then transferred to the calcination oven and calcined for 3 hours in air using the same ramp rate of 0.2 C./min.

Experimental Set-Up

(6) The experimental program was conducted on a fully automated 16-fold trickle-flow hydro process unit allowing uninterrupted catalyst testing. The operating range of this unit is summarized in Table.

(7) The 16-fold trickle-flow hydro processing unit operates as follows: The feed is preheated and mixed with hydrogen prior to entering the evaporation zone located on the top part of the set-up. Therein the mixture is heated to the selected reaction conditions. The pressure in the reaction section is maintained with a nitrogen pressure hold gas system (PHG) at the reactor outlet. The reactor section is composed of a 5 mm internal diameter tube with an isothermal zone of 50 mm at the highest operating temperature. Once the reaction has taken place the effluent is sent to a condenser kept at 75 C. Therein the gas is separated from the liquid and sent to an online GC (every 90 min). The liquid collected during reaction is stored and subsequently analyzed offline in a GC-MS. Both, the gas and liquid flows are precisely measured to obtain the combined effluent composition.

(8) TABLE-US-00001 TABLE 1 16-fold trickle-flow hydro processing unit specifications. Set-up specifications Temperature up to 500 C. Pressure up to 100 bara Operation mode Trickle-bed Catalysts volume up to 1.92 ml Reactor inner diameter 5 mm Gases H.sub.2, N.sub.2, Ar

Model Feed Composition

(9) The experiments have been carried out with a synthetic feed composed of paraffin's (25 wt %), mono-aromatics (20 wt %), di-aromatics (55 wt %) and tri-aromatics (5 wt %). This is summarized in table 2.

(10) TABLE-US-00002 TABLE 2 Model feed composition details. Model Feed Decane 25 wt % Propylbenzene 20 wt % Naphthalene 25 wt % 1-Methylnaphthalene 10 wt % 2-Methylnaphthalene 15 wt % Anthracene 2 wt % Phenantrene 3 wt %

Catalyst Preparation and Reactor Loading:

(11) The series of catalysts tested displayed different sizes and shapes. To minimize the influence of external mass transfer limitations and compare the intrinsic reactivity of each catalyst, similar sieved fractions were used. To this end, zeolite powders were bound with alumina sol, dried, calcined and sieved to the desired size. The zeolite containing samples (namely, solid acid catalysts and/or bifunctional catalysts) were mixed in a 7 to 3 ratio with Dispersal(R) and the resulting mixture mixed with water (1 to 5 ratio). Subsequently, the slurry was milled (5 min, 600 rpm), dried in a hot box (110 C., overnight), calcined in air (300 C., 6 h) and sieved to a target fraction of 125-160 m. On the other hand, the hydrogenation catalysts were milled and sieved to the same target fraction as the zeolite containing samples.

(12) The catalysts were loaded in the reactors together with silicon carbide diluent to form a bed which is ring shaped around a thermowell. A thorough calibration was performed to determine the isothermal zone of the 16 parallel reactor set-up under the temperature conditions tested.

Activation Protocol

(13) The activation and soaking protocol details are summarized in Table 3. After loading the catalyst in the reactor the activation procedure is performed to reduce the metal particles contained in the catalyst. Subsequently, the hydrogen feed is replaced by a mixture of hydrogen and the hydrocarbon feed used in the experiments while the sample is heated up slowly to reaction conditions. This is the so-called soaking procedure.

(14) TABLE-US-00003 TABLE 3 Activation and soaking protocol details. Activation procedure Soaking procedure Temperature 60-400 C. Temperature 60 C. Heating ramp 1 C./min, 2 h hold WHSV 2 h.sup.1 at 400 C. Purge step N.sub.2 during 10 min Purge step N.sub.2 during 10 min Reduction H.sub.2 H.sub.2 flow 10 (l/h) step Pressure 30 bara H2 flow 41.5 (l/h) Duration 16 h Pressure 30 bara Duration 460 min + Cool down

Experimental Results

(15) The physical mixture catalyst and bifunctional Pt/Zeolite Y catalyst, all prepared as described herein above, were contacted with the model feed using the following reaction conditions: a WHSV of 2 h.sup.1, a temperature of 450 C., a H.sub.2:HC ratio of 10 and a pressure of 60 bara or 100 bara. The process was performed in a continuous system that operated in steady state conditions. In Table 4 the experimental results are describes as as an average result of a measuring period of 24 h. Data were generated using GC-MS as described herein above.

(16) TABLE-US-00004 TABLE 4 Experimental results (all data provided in wt % except when indicated otherwise) Mono- Total catalyst Pressure C1 C2 C3 C4 C5-C9 aromatics LPG Pt/ 60 bara 0.8 3 28.1 47.6 5.7 3.2 78.7 Zeolite Y Physical 60 bara 0.2 0.9 12 18 3.8 40.4 31 mixture Pt/ 100 bara 0.9 2.3 28.6 47.3 9.3 2.7 78.6 Zeolite Y Physical 100 bara 0.3 1.7 16.9 29.3 6.3 27 52.2 mixture