CN1043520A - A kind of catalyst for cracking of producing low-carbon alkene - Google Patents

Abstract

A cracking catalyst, the carrier is 0-70% by weight of clay and 5-99% by weight of inorganic oxide, and its active component is a mixture of 1-50% by weight of ZSM-5 and Y-type molecular sieve. ZSM-5 molecular sieve accounts for 75-100% by weight in active components, and Y-type molecular sieve accounts for 0-25% by weight. The cracking catalyst is suitable for producing light olefins, especially propylene and butene. The catalyst is suitable for raw oils of various distillation ranges including heavy oils.

Description

The invention relates to a catalyst for the catalytic cracking process of petroleum hydrocarbons, especially a catalyst for producing low-carbon olefins through the catalytic cracking process of petroleum hydrocarbons.

Low-carbon olefins are widely used petrochemical raw materials. To produce low-carbon olefins from petroleum hydrocarbons, methods such as thermal cracking with natural gas, naphtha or light diesel oil as raw materials and heat carrier cracking of heavy hydrocarbons are generally used. Petroleum hydrocarbon catalytic cracking process produces gasoline and light diesel oil, and also by-products low-carbon olefins, and its output only accounts for less than 15% of the raw oil.

There have been many patent reports on the production of light olefins from hydrocarbons by using catalytic cracking methods. In some patents, metal-supported catalysts are used. The carrier can be silicon oxide, aluminum oxide or other oxides. Most of the metal elements used belong to IIB, ⅤB, VIIB and ⅧB group elements, they all have hydrogenation and dehydrogenation activity, and show dehydrogenation activity under high temperature and low pressure cracking reaction conditions, thereby accelerating the formation of low carbon olefins (USP3, 541, 179; USP3, 647, 682; DD225-135, SU1, 214, 726). For example, USP3,541,179 uses elements such as copper, manganese, chromium, vanadium, zinc, silver or cadmium as active components, and aluminum oxide or silicon oxide as a carrier. When using this kind of catalyst, since metal elements have dehydrogenation performance, while the cracking reaction is going on, the main side reaction related to the dehydrogenation performance, that is, the coking reaction of polymerization, is also accelerated accordingly, resulting in more carbon formation on the catalyst, so it can only be used Use light raw materials (final boiling point is generally less than 220 ° C).

In addition, some patents use solid acid catalysts. DD152, 356 introduces the use of amorphous silica-alumina as a catalyst to carry out catalytic cracking reactions of gasoline and vacuum gas oil at 600-800 ° C to produce low-carbon olefins, C ₂ ~30% yield of ~ _C4 olefins (e.g., ethylene 13.5%, propylene 6.3%, butene 10.5%). JP60-224, 428 introduces the use of ZSM-5 molecular sieve as the active component and alumina as the carrier catalyst, at a reaction temperature of 600-750 ° C, catalytic cracking of C ₅ -C ₂₅ paraffin raw materials, C ₂ -C ₄ The yield of olefins is about 30% (for example: space velocity 20-300 hours ^-1 , naphtha as raw material, ethylene 16%, propylene 14.1%; butene 1.8%). When the above technology is used, the reaction temperature is high, the requirements for equipment materials are high, the boiling point range of the reaction raw material is narrow, the raw material oil is light, and there is more ethylene in the product.

In recent years, in order to increase the octane number of gasoline produced by the catalytic cracking process, people add a small amount of shape-selective additives (USP4,309,280, USP4,521,298, USP4,552,648, USP3, 894, 933, USP 4, 522, 705). It is reported in USP4,309,280 that HZSM-5, which will account for 0.01-1% of the catalyst weight, is added to the reaction device separately. USP3,758,403 describes the use of ZSM-5 molecular sieves and macroporous molecular sieves (such as X, Y types) (the ratio of the two can be 1:10 to 3:1) as active components, and the carrier can have (the carrier is Inorganic oxides and carriers account for 99-5% of the weight of the catalyst). Using this catalyst, while increasing the octane number of gasoline, it also increases the yield of C ₃ and C ₄ olefins, but the amount is very small, for example , the yield of dry gas is about 8% by weight, and the yield of C ₃ -C ₄ olefins is about 10% by weight.

The object of the present invention is to provide a cracking catalyst for producing low-carbon olefins, especially propylene and butene, and concurrently producing gasoline and diesel oil.

The carrier of the catalyst provided by the invention is 0-70% (by catalyst weight) of clay and 5-99% of inorganic oxides, and the active component is a mixture of 1-50% ZSM-5 and Y-type molecular sieve; the active component Among them, ZSM-5 accounts for 75-100% by weight, and Y-type molecular sieve accounts for 0-25% by weight.

ZSM-5 molecular sieve is preferably HZSM-5 molecular sieve with SiO ₂ /Al ₂ O ₃ ratio of 20 to 200; Y-type molecular sieve can be Y-type that has been exchanged with rare earth metal ions or treated by physical and/or chemical methods Molecular sieves, preferably Y-type molecular sieves stabilized by physical and/or chemical methods; inorganic oxides can be silica, alumina or amorphous silica-alumina; clays can be natural or synthetic, usually used in Various clays for cracking catalyst supports, such as kaolin, halloysite, etc.

The preparation method of catalyst provided by the invention can have following two kinds:

Method I:

(1) Prepare aluminum sol, silica sol or silica-alumina sol or gel according to conventional methods. The colloidal solution can be acidic, preferably with a pH of 2 to 4. Add clay accounting for 0 to 70% of the weight of the catalyst and stir evenly , heating up to 50-100°C, standing for aging for 0.5-2 hours,

(2) A predetermined amount of ZSM-5 molecular sieve or a mixture of ZSM-5 and Y-type molecular sieve is added to the product of step (1) after beating with water, mixed evenly, and then formed, washed, filtered and dried according to the conventional method, namely Get the finished product.

Method II:

(1) The clay is beaten with water, and one of the inorganic acids including hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, etc. is added to make the slurry acidic, preferably PH2~4, and then add alumina and its precursors, oxidation An inorganic oxide including silicon and its precursors, silicon oxide-alumina and its precursors, stirred evenly, heated to 50-100°C, and aged for 0.5-2 hours.

(2) A predetermined amount of ZSM-5 molecular sieve or a mixture of ZSM-5 and Y-type molecular sieve is added to the product of step (1) after beating with water, mixed evenly, and then formed, washed, filtered and dried according to the conventional method, namely Get the finished product.

The ZSM-5 molecular sieve mentioned in the present invention can be prepared by conventional methods for preparing ZSM-5, such as hydrothermal synthesis. For example, use a certain amount of water glass, aluminum sulfate, water and template as raw materials, and react for a certain period of time under stirring at 100-170°C to obtain sodium-type ZSM-5 molecular sieve; through the conventional ion exchange process, that is Available ammonium type; the latter can be converted into hydrogen type by roasting. The template used can be various organic ammonia, inorganic ammonia or non-ammonia compounds commonly used as templates.

The prepared catalyst can be treated by processes such as ion exchange and/or roasting.

Adopting catalyst provided by the invention to carry out the catalytic cracking reaction of petroleum hydrocarbons has the following advantages to produce light olefins:

(1) The reaction temperature is 500-650°C, preferably 550-620°C, which is lower than the reaction temperature (600-800°C) in the prior art.

(2) The total yield of C ₂ -C ₄ olefins is as high as 40% by weight of the raw material (the prior art is 15-30% by weight).

(3) Among the C ₂ -C ₄ olefins, propylene and butene account for the vast majority (for example, C ₂ = 6.1%, C ₃ = 21.0%, C ₄ = 14.3%), and most of the existing technologies have relatively the highest amount of ethylene (For example, in JP60-222,428, C ₂ =16%, C ₃ =14.1%, C ₄ =1.8%).

(4) When the catalyst of the present invention is used, the octane number of the obtained gasoline is higher than that of conventional catalytic cracking gasoline, and the content of BTEX aromatics in gasoline is also high.

The present invention will be further described below by example.

Example 1

Mix 300 grams of distilled water with 100 grams of kaolin (Suzhou Jixuan 2 ^# ) (on a dry basis), add 10 milliliters of hydrochloric acid (Beijing Chemical Plant) solution with a concentration of 33% by weight, and then add 50 grams of quasi-thin water Bauxite (produced by Shandong Aluminum Factory) (calculated on a dry basis), and stirred evenly. Aging the slurry at 60-70°C for 1 hour, and then mixing it with a certain amount of HZSM-5 (Shanghai Dyeing No.7 Factory, SiO ₂ /Al ₂ O ₃ ratio of 60) with a solid content of 40% by weight , filtered, washed, dried at 250°C for 2 hours, and ground into powder to obtain catalyst A containing 18% by weight of HZSM-5 molecular sieve, 54.7% by weight of kaolin and 27.3% by weight of Al ₂ O ₃ .

Example 2

Mix 675 grams of water glass (Zhoucun Catalyst Factory of Qilu Petrochemical Corporation, containing SiO ₂ 124 g/L, modulus 3.3) with 452 grams of water and stir for 10 minutes, add 50 ml of hydrochloric acid solution with a concentration of 30% by weight, and stir for 10 minutes Then add 9 milliliters of hydrochloric acid solution, stir evenly, age for 1.5 hours, adjust the pH of the solution to 3.0 to 3.5 with hydrochloric acid solution, then add 176 grams of 28% by weight aluminum trichloride (Jinshan Chemical Plant) solution, mix well, add 74 Milliliter 16% by weight of ammonia water (Beijing Jinzhan Chemical Factory) solution, mix well, finally add 3 grams of HZSM-5 and stir evenly, then filter, wash, dry at 200°C for 2 hours, grind and pulverize to obtain 2% by weight of HZSM - Catalyst B of 5 and 98 wt% amorphous silica-alumina.

Example 3

Catalyst C is prepared in the same manner as Example 1, except that the HZSM-5 slurry is replaced by a certain amount of ultra-stable Y-type molecular sieve (USY) and HZSM-5 mixed slurry, and the prepared catalyst C contains 17.1% by weight of HZSM -5, 1.9% by weight of USY, 54.0% by weight of kaolin and 27.0% by weight of Al ₂ O ₃ .

The preparation of ultra-stable Y-type molecular sieve is as follows:

NaY molecular sieve (SiO ₂ /Al ₂ O ₃ ratio is 5.28, unit cell constant is 24.65) is double-crossed and double-baked, that is, exchanged with (NH ₄ ) ₂ SO ₄ solution, calcined in the environment of air and water vapor, and then exchanged and roasting once to obtain USY molecular sieve; the exchange conditions are: the weight ratio of water/NaY (on dry basis) is 15-20, and the weight ratio of (NH ₄ ) ₂ SO ₄ /NaY (on dry basis) is 0.5- 1.0, PH3, temperature 80-100°C, exchange time 60 minutes; roasting conditions: temperature 600-700°C, time 90-120 minutes, water vapor content 50%.

Example 4

Catalyst D was prepared in the same manner as in Example 3, except that catalyst D contained 15.9% by weight of HZSM-5, 4.4% by weight of USY, 53.1% by weight of kaolin and 26.6% by weight of alumina.

Example 5

Catalyst E was prepared in the same manner as in Example 1, except that catalyst E contained 48.1% by weight of HZSM-5 molecular sieve, 34.6% by weight of kaolin and 17.3% by weight of alumina.

Example 6

Mix 300 grams of water and 200 grams of pseudo-boehmite (produced by Shandong Aluminum Plant) evenly, add a mixture of 50 grams of HZSM-5 (on a dry basis) and 100 grams of water, stir evenly, and then filter, spray dry, After washing and drying at 400°C for 2 hours, a catalyst F containing 200% by weight of HZSM-5 and 80.0% by weight of alumina was obtained.

Example 7

In a small fixed fluidized bed reaction device, the catalytic cracking reaction of vacuum gas oil (see Table 1 for performance) was carried out to evaluate the performance of catalysts A, B, C and D, and compared with industrial cracking catalyst CRC-1 (weekly Village catalyst factory product, rare earth Y-type semi-synthetic cracking catalyst) and ZCM-7 (Zhoucun catalyst factory product, ultra-stable Y-type semi-synthetic cracking catalyst) for comparison. The catalyst was aged in 100% steam at 750°C for 4 hours before the reaction. Reaction conditions: temperature 580°C, weight space velocity 1 hour ^-1 , agent-oil ratio 5:1, water vapor/feed ratio 0.3, catalyst loading 180 g, the results are shown in Table 2.

In Table 2, the conversion rate is the weight percentage of the sum of cracked gas, gasoline fraction (that is, C ₅ ~205°C fraction), coke and losses in the feedstock. Diesel fractions are 205-330°C fractions.

Table 1 Density, 20°C, kg/ ^m3 carbon residue, heavy aniline point, °C sulfur, weight% nitrogen, weight% freezing point, °C molecular weight, distillation range, °C initial boiling point 5% 10% 50% 70% 90% 95% dry point 8730.15>1050.0730.10>50442346397411462489523535540

It can be seen from the table that the catalyst provided by the present invention has an activity level closer to that of the daily cracking catalyst, higher yield of low-carbon olefins and better selectivity of low-carbon olefins.

Example 8

On the normal pressure pulse microreactor, use catalyst A, C, E or F to carry out n-hexane cracking reaction, reaction conditions: temperature 580 ° C, catalyst 0.255 g, n-hexane is analytically pure, injection volume 1 microliter. The reaction results are shown in Table 3.

It can be seen from the table that the catalyst provided by the invention has good yield and selectivity of light olefins.

Example 9

Under different reaction conditions, catalyst A was used in the continuously regenerated fluid catalytic cracking small reactor to carry out cracking reactions of different feedstock oils. The results are shown in Table 4. In addition, the composition and octane number of gasoline produced by reacting vacuum gas oil with paraffin vacuum gas oil at 580°C were measured, and the results are shown in Table 5.

It can be seen from Table 4 that under different reaction conditions and using different raw material oils for reaction, the catalysts provided by the present invention all exhibit good activity and low-carbon olefin selectivity. It can be seen from Table 5 that the octane number of gasoline is as high as 84.6, while the octane number of gasoline produced by the conventional catalytic cracking process is generally about 78. In addition, the total aromatics content in gasoline can reach 50.46%. Among them, the currently widely used chemical raw materials- BTEX aromatics (that is, aromatics below C ₈ ) has 32.36%.

table 5 Occupying gasoline distillation points, heavy % saturated hydrocarbons 10.64 olefin 38.90 aromatics 50.46 bases, benzene 3.37 toluene 12.14 athylene 2.16 rooms, pacelene 11.00 toluene 3.69 rooms, toloorne 3.391, 3, 5 one triopene 1.58 tolozenezide 0.771, 3, 4-trimethylbenzene 5.57 other aromatics 6.79 Motor octane number 84.6

Example 10

Catalyst G is prepared on the industrial device according to the formula, flow process and process conditions of Example 1, and its physical and chemical properties are shown in Table 6. Use this catalyst in the medium-sized fluidized bed catalytic cracking reaction device to carry out the reaction of vacuum gas oil, and with The reaction results of the industrial catalyst ZCM-7 in the medium-sized riser catalytic cracking reactor were compared, and the results are shown in Table 7. The reaction conditions when catalyst G is used are: reaction temperature 580°C, reaction pressure (absolute pressure) 1.7×10 ⁵ Pa, solvent-to-oil ratio 9.8, weight space velocity 4.1 hr ^-1 . Reaction conditions when catalyst ZCM-7 is used: riser outlet temperature 494°C, reaction pressure 2.33×10 ⁵ Pa, agent-oil ratio 5.9. The catalyst is aged before the reaction. Catalyst G: 750°C, 6 hours, 50% water vapor, Catalyst ZCM-7: 780°C, 10 hours, 50% water vapor (after treatment, the micro reaction activity is 70).

Table 6 Chemical composition, weight % Al ₂ O ₃ Na ₂ OFe ₂ O ₃ SO ₄ 2- 51.00.0660.0561.4 Skeleton density, g/ml apparent density, g/ml pore volume, ml/g specific surface, ^m2 /g wear index, % ignition loss, weight % 2.40.80.221912.812.0 Sieve composition, weight%<20μm20~8040~80>80 4.223.662.010.2

As can be seen from Table 6 and Table 7, the catalyst provided by the present invention prepared by industrial equipment has qualified physical and chemical properties, and higher catalytic rate than industrial cracking catalysts, low carbon olefin yield and C ⁼ ₃ and C ⁼ ₄ Olefin selectivity.

Claims (8)

1, a kind of catalyst for cracking, it is characterized in that its carrier is the clay of 0～70% (in catalyst weight) and 5～99% inorganic oxide, its active ingredient is 1～50% the ZSM-5 and the mixture of Y zeolite, ZSM-5 accounts for 75～100 heavy % in the active ingredient, and Y zeolite accounts for 0～25 heavy %.

2, catalyzer according to claim 1 is characterized in that preferably its SiO of said ZSM-5 ₂/ Al ₂O ₃Than the HZSM-5 molecular sieve that is 20～200.

3, catalyzer according to claim 1 is characterized in that said inorganic oxide is aluminum oxide, silicon oxide or amorphous aluminum silicide.

4, catalyzer according to claim 1, it is characterized in that said Y zeolite be through rare earth exchanged or through physics and/Y zeolite that chemical process was handled.

5, according to claim 1,2,3, one of 4 described catalyzer, it is characterized in that its preparation method is:

(1) in aluminium colloidal sol, silicon sol, silicon-aluminum sol or the gel, adding accounts for catalyzer and weighs 0～70% clay, stirs, and is warming up to 50～100 ℃, leaves standstill aging 0.5～2 hour;

(2) after the mixture of ZSM-5 molecular sieve or ZSM-5 and Y zeolite adds the water making beating, add in (1) the step gains, mix moulding, washing, drying.

6, according to claim 1,2,3, one of 4 described catalyzer, it is characterized in that its preparation method can be:

(1) clay adds the water making beating, add a kind of in the mineral acid comprise hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, make slurries be acid, add a kind of among silicon oxide or its precursor, aluminum oxide or precursor, amorphous aluminum silicide or the precursor then, stir, be warming up to 50～100 ℃, left standstill aging 0.5～2 hour;

(2) mixture of ZSM-5 molecular sieve or ZSM-5 and Y zeolite adds the deionized water making beating, is added in (1) the step gains, mixes, moulding, washing, drying.

7, catalyzer according to claim 5 is characterized in that said aluminium colloidal sol, silicon sol, silicon-aluminum sol or gel are tart, preferably PH2～4.

8, catalyzer according to claim 6, the PH that it is characterized in that the clay slurry in said (1) step preferably 2～4.