CN100377784C - A kind of metal-modified SAPO-34 molecular sieve and its application - Google Patents

Abstract

The present invention discloses a metal modified SAPO-34 molecular sieve. The present invention is characterized in that the chemistry expression of the molecular sieve without water is (0.1 to 15) M2O3. (0.9 to 72) Al2O3. (1 to 78) P2O5. (0.4 to 97) SiO2 according to the mass of oxide, wherein M is selected from one or two kinds of the transmission metal of Fe, Co and Ni. The molecular sieve is applied to the cracking process of petroleum hydrocarbon as an active component for catalysis; compared with the molecular sieve provided by the prior art, the present invention increases the yield and the selectivity of C2 to C4 olefins, and has higher yield of liquid gas.

Description

A kind of metal-modified SAPO-34 molecular sieve and its application

technical field

The present invention relates to a molecular sieve and its application, more specifically to a metal-modified SAPO-34 molecular sieve and the application of the molecular sieve to increase the content of propylene in the product under cracking reaction conditions.

technical background

Steam thermal cracking and catalytic cracking of hydrocarbons are important industrial processes for the production of propylene, of which propylene in FCC units provides about 30% of the demand. Due to the sheer volume of production, small improvements in operational efficiency can translate into significant gains. Catalysts play an important role in the more selective conversion of hydrocarbons to olefins.

Catalysts containing mesoporous zeolites can crack naphtha into small olefin molecules such as ethylene, propylene and butene. Such as ZSM-5 zeolite with MFI structure: In USP3,758,403, it is disclosed that adding ZSM-5 molecular sieve to the catalytic cracking catalyst can increase the octane number of gasoline and increase the yield of C ₃ -C ₄ olefins. USP 4,922,051 describes the cracking of C2-C12 paraffins with a composite catalyst preferably comprising 25% ZSM-5 with a conversion greater than 90% and a product containing at least 55% C2-4 and C6-C8 aromatics . This type of zeolite catalyst belonging to crystalline aluminosilicate has many invention patents in this field.

In addition, USP 4,440,871 proposes the selective production of light hydrocarbons and olefins by cracking hydrocarbon feedstocks with silicoaluminophosphate (SAPO) molecular sieves. SAPO molecular sieves have AlO ₄ , SiO ₄ and PO ₄ tetrahedral networks connected by oxygen atoms, pores in the crystal, acidity produced by substitution of P(V) or Al(III) by tetravalent Si or substitution by metal Me(II) The acidity produced by Al(III) makes the molecular sieve play an important role in separation and catalysis. It is proposed in CN1305445A that under cracking conditions, hydrocarbons are contacted with SAPO, MeAPO (aluminum phosphorus molecular sieve with metal isomorphous substitution of Al), MeASPO (silicon aluminum phosphorus molecular sieve with metal isomorphous substitution of Al) etc. to improve the cracking of hydrocarbon raw materials into propylene. Selective methods, especially SAPO-11 and SAPO-34 are proposed to obtain better propylene selectivity than ZSM-5 in the cracking process of hexene feedstock.

However, the performance of SAPO-34 molecular sieves with a pore size of only 3.8 x 3.8 Angstroms in hydrocarbon cracking conversion after modification with metals has not been recognized in the art.

Contents of the invention

One of the objectives of the present invention is to provide a metal-modified SAPO-34 molecular sieve, and the second objective is to provide the application of the molecular sieve in the cracking process.

The metal-modified SAPO-34 molecular sieve provided by the present invention has an anhydrous chemical expression of (0.1～15)M _x O _y ·(0.9～72)Al ₂ O ₃ ·(1～ 78)P ₂ O ₅ ·(0.4～97)SiO ₂ , preferably (0.5～10)M _x O _y (5～50)Al ₂ O ₃ ·(10～70)P ₂ O ₅ ·(5～50) SiO ₂ , wherein M is selected from one or two transition metal elements Fe, Co and Ni, preferably Fe, x represents the number of atoms of M, and y represents a number required to satisfy the oxidation state of M.

We know that SAPO molecular sieve has a three-dimensional microporous crystal framework structure of PO ₂ ⁺ , AlO ₂ ⁺ and SiO ₂ tetrahedral units, and its chemical composition (anhydrous) is: mR: ( _Six Al _y P _z )O ₂ , where "R" is the _organic template agent existing in the intracrystalline pore system, "m" is the number of moles of "R" present per _mole of ( _SixAlyPz ) _O2 , and its value is 0-0.3, "x ", "y", and "z" are respectively the mole fractions of silicon, aluminum and phosphorus, and satisfy x+y+z=1. Typical SAPO molecular sieves are SAPO-17, SAPO-18, SAPO-34, SAPO-44, etc. Among them, SAPO-34 molecular sieve is an 8-membered ring channel with a CHA structure, and the pore size is 3.8×3.8 angstroms. The method for synthesizing the molecular sieve is disclosed in documents such as CN1096496A and USP4,440,871.

The metal-modified SAPO-34 molecular sieves provided by the present invention are usually water-soluble salts of metal elements, such as ferric sulfate, ferrous sulfate, ferric nitrate, ferric chloride, ferrous chloride, cobalt sulfate, cobalt nitrate, chlorine Cobalt oxide, nickel sulfate, nickel nitrate or nickel chloride, etc., according to the amount to be loaded on the molecular sieve, they are dissolved in a solution consisting of 0-90% by weight of ethanol and 10-100% by weight of water to make impregnation liquid, and then according to the conventional equal impregnation method, the zeolite is impregnated in the impregnating liquid, and after drying, it is obtained by roasting at 400-800°C for 0.5-8 hours, wherein the roasting process can also be carried out under a steam atmosphere. conduct.

The metal-modified SAPO-34 molecular sieve provided by the invention has better performance of increasing the propylene content in the petroleum hydrocarbon cracking process. For example, at the weight ratio of basic catalyst:molecular sieve=95:5, reaction temperature 500°C, regeneration temperature 600°C, agent-to-oil ratio 2.94, under the catalytic cracking fixed bed micro-reaction evaluation conditions of 5 grams of catalyst reserve, adopt the present invention to provide Under the condition that the conversion rate of the molecular sieve does not change much and the increase of coke and dry gas is not large, the ratio of C ₃ ⁼ /total C ₃ is 0.70-0.75, the concentration of propylene in the liquefied gas is 41.61-43.08, and the yield of propylene is 12.75-13.79 , the yield of liquefied gas is 30.64-32.01, while the corresponding values of comparative examples are 0.35-0.60, 35.61-37.04, 7.66-11.03, 21.51-29.78.

The metal-modified SAPO-34 molecular sieve provided by the present invention can be used as an active component of a catalyst or an auxiliary agent in the cracking process of petroleum hydrocarbons, and its content is about 1 to 50% based on the proportion in the catalyst or auxiliary agent. Heavy%.

Detailed ways

The following examples will further illustrate the present invention, but do not thereby limit the present invention.

In each example and comparative example, the content of Fe ₂ O ₃ , Co ₂ O ₃ , Ni ₂ O ₃ , Al ₂ O ₃ , SiO ₂ and P ₂ O ₅ in the product molecular sieve was determined by X-ray fluorescence method (see "Petroleum Chemical Analysis Methods (RIPP Experimental Method), edited by Yang Cuiding et al., Science Press, published in 1990).

Comparative example 1

In this comparative example, SAPO-34 molecular sieves were prepared according to the process provided in CN1096496A.

In 250 grams of deionized water, add 105.6 grams of orthophosphoric acid solution containing H ₃ PO ₄ 85wt% and 58.8 grams of pseudo-boehmite powder containing 72.18 weight percent of Al ₂ O ₃ , stir well until uniform, then add 49.5 grams of SiO ₂ 40% by weight silica sol, 118 grams of deionized water and 72 grams of diethylamine. Stir well to make a gel, pack it into a stainless steel autoclave lined with polytetrafluoroethylene, age at 100°C for 24 hours, and react at 200°C for 72 hours. Then _the solid product was filtered out, washed _with water, _{dried ,} and roasted at 550°C for 4 hours to remove the organic amine to obtain a molecular sieve _.

Comparative example 2

According to CN1465527A, a phosphorus-iron modified molecular sieve with MFI structure was prepared.

20gNH ₄ Cl was dissolved in 1000g water, and 100g (dry basis) crystallization product ZSM-5 molecular sieve (manufactured by Changling Catalyst Factory, synthesized without amine, SiO ₂ /Al ₂ O ₃ =30) was added to this solution. After exchanging at 90°C for 0.5h, filter the filter cake; add 3.2gH ₃ PO ₄ (concentration 85%) and 8.7g Fe(NO ₃ ) ₃ 9H ₂ O to dissolve in 90g water, mix with the filter cake, immerse and dry; the obtained sample Baking treatment at 550°C for 2 hours. The elemental analysis chemical composition is 0.1Na ₂ O·4.8Al ₂ O ₃ ·2.0P ₂ O ₅ ·1.7Fe ₂ O ₃ ·91.4SiO ₂ .

Example 1

6.6gFe(NO ₃ ) ₃ .9H ₂ O was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with the SAPO-34 molecular sieve prepared according to the process provided in CN1096496A with 100g (dry basis), impregnated and dried, the obtained sample was in Calcined at 550°C for 2 hours to obtain molecular sieves, the chemical composition of which is as follows: 1.3Fe ₂ O ₃ ·20.1Al ₂ O ₃ ·52.2P ₂ O ₅ ·26.4SiO ₂

Example 2

_3.1gFeCl was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with 100g (dry basis) SAPO-34 molecular sieve prepared according to the process provided in CN1096496A, impregnated and dried, and the obtained sample was roasted at 550°C for 2 hours to obtain Molecular sieve, its elemental analysis chemical composition is: 1.5Fe ₂ O ₃ 6.5Al ₂ O ₃ 44.7P ₂ O ₅ 47.3SiO ₂

Example 3

Dissolve 4.6g FeSO ₄ 6H ₂ O in a mixed solution of 90g water and 10g ethanol, mix with 100g (dry basis) SAPO-34 molecular sieve prepared according to the process provided in CN1096496A, impregnate and dry; the obtained sample is roasted at 550°C After 2 hours, the molecular sieve was obtained, and its elemental analysis chemical composition was: 1.4Fe ₂ O ₃ 48.1Al ₂ O ₃ 45.2P ₂ O ₅ 5.3SiO ₂

Example 4

7.4gCo(NO ₃ ) ₂ 6H ₂ O was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with 100g (dry basis) according to the SAPO-34 molecular sieve prepared by the process provided in CN1096496A; Calcined at 550°C for 2 hours to obtain molecular sieves, the chemical composition of which is as follows: 2.0Co ₂ O ₃ ·19.9Al ₂ O ₃ ·51.9P ₂ O ₅ ·26.2SiO ₂

Example 5

6.7gNi(NO ₃ ) ₂ 6H ₂ O was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with the SAPO-34 molecular sieve prepared according to the process provided in CN1096496A with 100g (dry basis) impregnated and dried; Gained sample was in Calcined at 550°C for 2 hours to obtain molecular sieves, the chemical composition of which is as follows: 1.8Ni ₂ O ₃ ·19.6Al ₂ O ₃ ·52.3P ₂ O ₅ ·26.3SiO ₂

Example 6

2.6gFe(NO ₃ ) ₃ .9H ₂ O was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with the SAPO-34 molecular sieve prepared according to the process provided in CN1096496A with 100g (dry basis) and impregnated and dried; Gained sample was in Calcined at 550°C for 2 hours to obtain molecular sieves, the chemical composition of which is as follows: 0.5Fe ₂ O ₃ ·17.2Al ₂ O ₃ ·67.8P ₂ O ₅ ·14.5SiO ₂

Example 7

28.3gFe(NO ₃ ) ₃ .9H ₂ O was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with the SAPO-34 molecular sieve prepared according to the process provided in CN1096496A with 100g (dry basis); Calcined at 550°C for 2 hours to obtain molecular sieves, the chemical composition of which is as follows: 5.2Fe ₂ O ₃ ·38.7Al ₂ O ₃ ·10.5P ₂ O ₅ ·45.6SiO ₂

Example 8

57.9gFe(NO ₃ ) ₃ .9H ₂ O was dissolved in the mixed solution of 90g water and 10g ethanol, mixed with the SAPO-34 molecular sieve prepared according to the process provided in CN1096496A with 100g (dry basis); Calcined at 550°C for 2 hours to obtain molecular sieves, the chemical composition of which is as follows: 10.1Fe ₂ O ₃ ·17.7Al ₂ O ₃ ·48.2P ₂ O ₅ ·24SiO ₂

Example 9

5.9gFe(NO ₃ ) ₃ 9H ₂ O and 3.8g Co(NO ₃ ) ₂ 6H ₂ O were dissolved in a mixed solution of 90g water and 10g ethanol, and 100g (dry basis) was prepared according to the process provided in CN1096496A SAPO-34 molecular sieves were mixed, impregnated and dried; the obtained sample was roasted at 550°C for 2 hours to obtain a molecular sieve, and its elemental analysis chemical composition was: 1.0Fe ₂ O ₃ ·1.1Co ₂ O ₃ ·18.7Al ₂ O ₃ ·49.3P ₂ O ₅ ·29.9SiO ₂

Example 10

5.9gFe(NO ₃ ) ₃ 9H ₂ O and 6.0gNi(NO ₃ ) ₂ 6H ₂ O were dissolved in a mixed solution of 90g water and 10g ethanol, and 100g (dry basis) was prepared according to the process provided in CN1096496A SAPO-34 molecular sieves were mixed and impregnated and dried; the obtained samples were roasted at 550°C for 2 hours to obtain molecular sieves. The chemical composition of the elemental analysis was: 1.1Fe ₂ O ₃ ·1.4Ni ₂ O ₃ ·19.6Al ₂ O ₃ ·45.4P ₂ O ₅ ·32.5SiO ₂

Example 11

This example illustrates the effect of the molecular sieve provided by the present invention in the catalytic cracking probe reaction of pure hydrocarbons.

The samples prepared in the above examples and comparative examples were subjected to aging treatment at 800°C and 100% water vapor for 4 hours on a fixed bed aging device, and pressed into tablets to screen out 20-40 mesh particles. For evaluation, the raw material for cracking is hexane, and the evaluation conditions are as follows: feed amount 1g, reaction temperature 600°C, and catalyst storage amount 1g. The evaluation results are listed in Table 1.

Table 1

instance number Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative example 1 Comparative example 2 H2, w% 6.41 5.27 5.67 5.48 5.81 5.43 6.13 5.77 5.87 5.75 5.58 5.64 CH4, w% 14.10 13.19 15.84 13.82 12.87 13.09 14.02 13.76 13.94 13.90 5.85 12.84 C2H6, w% 8.33 9.23 8.04 8.75 8.92 9.14 8.46 8.66 8.58 8.63 10.13 8.67 C2H4, w% 17.31 16.04 18.91 16.95 16.10 16.06 17.20 16.94 17.10 17.06 10.92 16.51 C3H8, w% 10.90 13.63 10.64 14.13 14.75 13.97 11.87 13.52 12.77 13.18 37.13 18.59 C3H6, w% 33.65 33.63 33.57 32.11 31.78 33.08 33.19 32.32 32.76 32.56 15.01 28.00 IC4H10, w% 1.28 1.32 0.95 1.37 1.57 1.40 1.31 1.38 1.33 1.34 4.01 1.87 NC4H10, w% 2.24 2.42 2.13 2.54 2.66 2.49 2.33 2.50 2.41 2.45 5.63 3.18 C4=,w% 1.60 1.32 1.18 1.24 1.42 1.35 1.49 1.35 1.39 1.35 1.08 1.15 IC4=, w% 1.28 1.54 0.95 1.34 1.52 1.53 1.30 1.35 1.32 1.32 2.49 1.41 Inverse C4=, w% 1.60 1.32 1.18 1.25 1.44 1.36 1.50 1.36 1.40 1.36 1.22 1.19 Shun C4=, w% 1.28 1.10 0.95 1.02 1.17 1.12 1.20 1.10 1.13 1.10 0.95 0.95 C3＝/∑C3 0.76 0.71 0.76 0.69 0.68 0.70 0.74 0.70 0.72 0.71 0.29 0.60 C2＝/∑C2 0.68 0.63 0.70 0.66 0.64 0.63 0.67 0.66 0.67 0.66 0.52 0.66 C2＝+C3＝ 50.96 49.67 52.48 49.06 47.88 49.13 50.39 49.26 49.86 49.62 25.93 44.52 C3＝/C2＝ 1.94 2.10 1.78 1.89 1.97 2.06 1.93 1.91 1.91 1.91 1.37 1.70 C3＝/C4＝ 5.83 6.38 7.89 6.62 5.73 6.19 6.07 6.38 6.29 6.39 2.61 5.95

As can be seen from Table 1, using the metal-modified SAPO-34 molecular sieve provided by the present invention in the hexane cracking reaction, compared with the results of Comparative Examples 1 and 2, under the condition that the hydrogen is substantially constant, the selection of low-carbon olefins Remarkably increased, C ₃ ⁼ /∑C ₃ ratio greatly increased.

Example 12

This example illustrates the effect of using the molecular sieve provided by the present invention in the catalytic cracking of petroleum hydrocarbons on the yield and selectivity of C ₂ -C ₄ olefins.

The sample that above-mentioned example and comparative example are made carries out 800 ℃, 100% water vapor aging treatment on fixed-bed aging device respectively for 4 hours, and presses tablet and sieves out 20-40 mesh particle, then uses catalyst DOCP (Changling Catalyst Factory Production) industrial balancer as the basic catalyst, respectively mixed with each molecular sieve at a weight ratio of 95:5 evenly, and then evaluated on the catalytic cracking fixed bed micro-reactor, the evaluation conditions were reaction temperature 500 ° C, regeneration temperature 600 ° C, The agent-to-oil ratio is 2.94, and the catalyst reserve is 5 grams.

The properties of raw oil are shown in Table 2. The evaluation results are listed in Table 3.

Table 2

project analyze data Density (20°C)/g/cm³ Refraction (70°C) Viscosity (80°C)/mm²/s Vacuum distillation range/°C Initial boiling point 5% 10% 30% 50% 70% 90% acid value/mgKOH/g residual carbon/% ash/%S content/%N content/%C, H content/%CH 0.87311.468217.5618939841845749754973.5%, 560°C 0.070.70.050.120.1186.4313.53

table 3

instance number Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative example 1 Comparative example 2  Material balance/m% dry gas 2.02 2.01 1.95 1.90 1.95 1.99 1.98 1.97 1.95 1.94 1.84 1.96 Liquefied gas 31.38 31.25 32.01 31.03 30.64 31.07 31.28 30.82 31.18 31.15 21.51 29.78 gasoline 42.35 43.01 43.56 44.86 44.07 43.33 43.10 43.75 43.80 44.02 51.44 45.01 diesel fuel 12.11 11.90 10.19 9.64 10.79 11.57 11.37 11.12 10.68 10.47 11.54 11.51 heavy oil 9.28 9.15 9.71 9.62 9.55 9.27 9.38 9.43 9.48 9.50 10.95 9.02 Coke 2.86 2.68 2.58 2.95 3.00 2.78 2.89 2.90 2.91 2.92 2.72 2.72 Conversion rate/m% 78.61 78.95 80.10 80.74 79.66 79.16 79.25 79.45 79.85 80.02 77.51 79.47 Propylene, m% 13.34 13.22 13.79 12.96 12.75 13.08 13.23 12.89 13.12 13.09 7.66 11.03 Propylene concentration in liquefied gas, % 42.51 42.30 43.08 41.77 41.61 42.09 42.29 41.82 42.08 42.02 35.61 37.04 Total butene, m% 10.43 10.12 10.77 10.03 9.98 10.08 10.31 10.02 10.20 10.16 6.73 9.32 C₂^＝/total C₂ 0.74 0.73 0.74 0.70 0.73 0.73 0.73 0.73 0.72 0.71 0.63 0.71 C₃^＝/total C₃ 0.75 0.77 0.74 0.71 0.70 0.75 0.74 0.72 0.73 0.72 0.35 0.60

As can be seen from Table 3, after adding the metal-modified SAPO-34 molecular sieve provided by the present invention in the catalytic cracking catalyst, compared with the results of the comparative examples, the change in conversion rate is little, coke, dry gas increase rate is little Under certain conditions, the C ₃ ⁼ /total C ₃ ratio increases, the propylene concentration in the liquefied gas increases, the propylene yield and selectivity increase, and the liquefied gas yield is higher.

Claims (6)

1. metal-modified SAPO-34 molecular sieve is characterized in that the anhydrous chemical expression of this molecular sieve, counts (0.1～15) M with the quality of oxide _xO _y(0.9～72) Al ₂O ₃(1～78) P ₂O ₅(0.4～97) SiO ₂Wherein, M is selected from transition metal Fe, among Co and the Ni one or both, x represents the atomicity of M, y represents to satisfy the required number of M oxidation state, metal-modified process is the water soluble salt with transition metal, according to the amount of on the SAPO-34 molecular sieve, intending load, they are dissolved in the solution of being made up of the water of the ethanol of 0～90 weight % and 10～100 weight % make maceration extract, according to the equivalent impregnation method of routine the SAPO-34 molecular sieve is flooded in maceration extract, dry back obtained metal-modified SAPO-34 molecular sieve in 0.5～8 hour 400～800 ℃ of following calcination process again.

2. according to the molecular sieve of claim 1, it is characterized in that anhydrous chemical expression, count (0.5～10) M with the quality of oxide _xO _y(5～50) Al ₂O ₃(10～70) P ₂O ₅(5～50) SiO ₂

3. according to the molecular sieve of claim 1 or 2, said transition metal is Fe.

4. according to the molecular sieve of claim 1 or 2, said transition metal is Fe and Co.

5. according to the molecular sieve of claim 1 or 2, said transition metal is Fe and Ni.

6. claim 1 or 2 molecular sieve are applied in the cracking process of petroleum hydrocarbon as the active component of catalyst or auxiliary agent, and its content is counted 1～50 weight % with proportion in catalyst or auxiliary agent.