CN1544151A - A kind of molecular sieve catalyst and preparation method thereof - Google Patents

Abstract

A molecular sieve catalyst is composed of La0.5-3.0ZrHZSM-5 molecular sieve 97.0-99.5 in weight percentage, and the heteroatom molecular sieve ZrHZSM-5 is modified by using lanthanum. The preparation method has the advantages of simple and easy preparation method, strong catalyst stability, and single-pass service life of more than 450 hours.

Description

A kind of molecular sieve catalyst and preparation method thereof

Technical field:

The invention belongs to a molecular sieve catalyst and a preparation method thereof, in particular to a high-stability molecular sieve catalyst and a preparation method thereof for producing diesel oil fractions by lamination of olefins.

Background technique:

An important chemical reaction in which olefin monomers are stacked to form compounds containing one or more structural units that are repeatedly connected. It is an effective way to synthesize liquid fuels, plastics, drugs, dyes, resins, detergents, lubricating oils, and additives . Edited by Gao Zi, Sinopec Press's "Zeolite Catalysis and Separation" (1999) pointed out that low-carbon olefin oligomerization (such as propylene, butene) can be used to synthesize environmentally friendly liquid fuels, and the content of aromatics in the product is very low. Catalysts used in the conversion process in industry can be mainly divided into two types of acidic catalysts: molecular sieve and non-molecular sieve; among them, molecular sieve catalysts have the advantages of high activity, good selectivity, high stability and strong anti-toxicity. It can promote the transformation of low-carbon olefins into gasoline, diesel and other liquid fuels. The SKP zeolite catalysts currently used in industry are mainly used in the process of olefin oligomerization to produce gasoline. However, with the current rapid increase in diesel consumption and environmental protection requirements, my country's resources The current state of technology and technology determines that the diesel-steam ratio in the production of liquid fuels using petroleum as raw material is low, and the grade is low, which is far from meeting the demand. Recently, many researchers at home and abroad have conducted a lot of research on catalysts and catalytic processes for the oligomerization of light olefins. We have used modified molecular sieve ZrZSM-5 as a catalyst for olefin oligomerization, because the presence of Zr has adjusted the reaction characteristics of the ZSM-5 molecular sieve catalyst, so the catalyst has high selectivity, and the diesel fraction C ₁₂ -C ₁₈ fraction in the product can reach 78 %, (referring to patent: 01119414.6H type ZSM-5 molecular sieve catalyst in the application of low-carbon olefin synthesis C ₁₂ -C ₁₈ ), but this catalyst is in long-term continuous operation, and its one-way life is below 350 hours, so it will The frequent regeneration of the catalyst is not only costly, but also cumbersome to operate, so it is far from meeting the needs of actual industrial production.

Invention content:

The object of the present invention is to provide a long-life and high-stability La/ZrHZSM-5 molecular sieve catalyst, its preparation method and its application in the synthesis of C ₁₂ -C ₁₈ from low carbon olefins.

Catalyst weight percent of the present invention consists of:

La: 0.5-3.0

ZrHZSM-5 molecular sieve: 97.0-99.5.

The aforementioned ZrHZSM-5 molecular sieve has an nSiO ₂ /nAl ₂ O ₃ ratio of 20-200, and the Zr content in the molecular sieve is 0.5-3.0 wt%.

The preparation method of catalyst of the present invention comprises the steps:

(1) silicon source, sodium salt and deionized water are prepared into solution A; aluminum source, acid and deionized water are prepared into solution B in molar ratio; zirconium source and deionized water are prepared into solution C, and the Under stirring, add solution B to solution A dropwise, then add organic template, then add solution C, stir to mix evenly, age, crystallize, separate solid and liquid, dry and roast the filter cake to obtain molecular sieve powder , and then exchanged with HCL solution, after roasting, the ZrHZSM-5 molecular sieve with nSiO ₂ /nAl ₂ O ₃ ratio of 20-200 and Zr content of 0.5-3.0wt% can be obtained. For the detailed preparation method, see the patent application number 03124261.8 A method for rapidly synthesizing ZSM-5 molecular sieves containing zirconium atoms;

(2) Roasting the ZrHZSM-5 molecular sieve of step (1) at 520-540° C. for 3-5 hours to remove its physically adsorbed impurities;

(3) Mix the molecular sieve after step (2) with the auxiliary agent in a weight ratio of 63-72:28-37, and grind evenly;

(4) Add nitric acid into a 2-4% solution dropwise into the material ground in step (3), knead properly, extrude, and dry at 100-120°C;

(5) Pulverize the dried material in step (4) to 10-40 mesh, then roast at 500-520° C. for 3-5 hours to remove nitric acid and moisture;

(6) The inorganic acid is prepared into a solution with a concentration of 0.1-0.5mol;

(7) The lanthanum salt and the above-mentioned inorganic acid solution are prepared into an ion-exchange modifying solution Y with a concentration of lanthanum in the solution of 0.1-0.5mol;

(8) Carry out ion exchange for 1-3 hours under electromagnetic stirring at 20-80° C. according to the ratio of 1 gram of catalyst weight with 6-8 ml ion exchange liquid;

(9) Then filter the solution and wash it with ion-free water until the pH value is 6-7, keep it in an oven at 100-120°C for 3-8 hours, and then bake it at 300-500°C for 3-5 hours to obtain catalyst.

As mentioned above, lanthanum salts are water-soluble or dilute acid-soluble salts such as lanthanum nitrate, lanthanum acetate, and lanthanum sulfate;

As mentioned above, the inorganic acid is nitric acid, sulfuric acid, hydrochloric acid, etc.;

The additives mentioned above are common molecular sieve forming binders such as γ-alumina, thin water alumina, and diatomaceous earth.

The application conditions of the catalyst are that the reaction raw material is mixed light olefins, the reaction temperature T is 250-290°C, the reaction pressure P is 2.5-4.0Mpa, and the LHSV is 0.5-2.0hr ^-1 .

The advantages of the present invention are:

(1) The heteroatom molecular sieve ZrHZSM-5 is modified with lanthanum, and the preparation method is simple and feasible.

(2) The catalyst has strong stability, and the single-pass life can reach more than 450 hours.

Detailed ways:

Example 1

(1) SiO ₂ : Na ₂ O : H ₂ O = 0.02 : 0.006 : 1 is formulated into A solution by molar ratio of silicon source, sodium salt and deionized water; Aluminum source: acid: deionized water = 0.001: 0.04: 1 to prepare solution B; zirconium source and deionized water in molar ratio to zirconium source: deionized water = 0.001: 1 to prepare solution C.

The ingredients are operated in the following order: under vigorous stirring, add 200ml of B solution to 500ml of A solution dropwise, and stir evenly. Then add 22.4g hexamethylenediamine, then add 200ml solution C, stir for 30 minutes, make it mix well. Finally, transfer the prepared gel mixture into a synthesis kettle and seal it.

Under uniform stirring, the temperature was raised to 120°C at a heating rate of 1°C/min, and kept at a constant temperature for 40 hours. Then continue to heat up to 170°C at a heating rate of 1°C/min, and keep the temperature for 30 hours to complete. Cool rapidly with ice water to stop the crystallization, and remove the mixture in the synthesis kettle.

The above mixture is subjected to solid-liquid separation, and the obtained solid is washed with deionized water until the pH of the washing solution is 8-9. Dry at 120°C for 12 hours to obtain the raw molecular sieve powder. Then roast at 540°C to remove the template agent, and then exchange it with 0.5mol/l HCL solution for 3 hours, and then roast to obtain the ZrHZSM-5 molecular sieve with a molecular sieve nSiO ₂ /nAl ₂ O ₃ ratio of 24 and a Zrwt% of 0.82.

(2) Roasting 20 grams of the molecular sieve obtained in (1) at 540° C. for 3 hours to remove its adsorbed impurities;

(3) 13 grams of molecular sieves treated in step (2) and 7 grams of γ-Al ₂ O ₃ were mixed in a mortar and ground evenly;

(4) Add 3% nitric acid solution dropwise to the ground material and knead properly, extrude it into a columnar shape of Φ2 with a manual screw extruder, put it in an oven and dry it at 120°C;

(5) Then crush strip molecular sieves to 10-40 mesh, put them in a muffle furnace and heat up to 520 ° C for 5 hours to remove nitric acid and moisture, and take them out when the temperature drops below 60 ° C;

(6) Accurately weigh 1.97 grams of 32% hydrochloric acid and put it into a volumetric flask, add deionized water to 200ml and be mixed with a solution Y of _0.1mol ; then weigh 2.34 grams of lanthanum nitrate and add it to the solution _Y1 , and stir until until it becomes a colorless transparent liquid;

(7) Weigh 10 grams of molecular sieve prepared in step (4) and put it into the Erlenmeyer flask, add 120ml of solution J, and maintain it at 80°C for 2 hours on the electromagnetic stirring heater;

(8) Filter the solution after cooling down, and wash with deionized water until the pH value is about 6;

(9) Put it into an oven at 110° C. for 5 hours, then put it into a muffle furnace and bake it at 200° C. for 3 hours to obtain a catalyst, wherein the La content is 0.52 wt % and the ZrHZSM-5 molecular sieve is 99.48 wt %.

Example 2

(1) First, the ZrHZSM-5 molecular sieve with nSiO ₂ /nAl ₂ O ₃ ratio of 68.6, Zr(wt)%: 1.21 was roasted at 540°C for 3 hours to remove the adsorbed impurities; the specific preparation process of ZrHZSM-5 Refer to the synthetic method of a kind of rapid synthesis zirconium atom-containing ZSM-5 molecular sieve of patent 03124261.8, the following examples are the same;

(2) Combine 13 grams of molecular sieve treated in step (1) with 6 grams of γ-Al ₂ O ₃ . At the same time, put it into the mortar and mix it, and grind it evenly;

(3) Add 3% nitric acid solution dropwise to the ground material and knead appropriately, extrude it into a columnar shape of Φ2 with a manual screw extruder, put it in an oven and dry it at 105°C;

(4) Then crush the strip molecular sieve to 10-40 mesh and put it in a muffle furnace and heat it up to 510°C for 3 hours to roast to remove nitric acid and moisture, and take it out when the temperature drops below 60°C;

(5) Accurately weigh 7.0 grams of 36% nitric acid and put it into a volumetric flask, add deionized water to 200ml to be mixed with a 0.2mol solution Y ₂ ; then weigh 4.0 grams of lanthanum nitrate and add it to solution J, and stir until it becomes until it is a colorless and transparent liquid;

(6) Weigh 10 grams of the molecular sieve prepared in step (4) and put it into the Erlenmeyer flask, add 150ml of solution Y ₂ , and maintain it at 60°C for 2 hours on the electromagnetic stirring heater;

(7) Filter the solution after cooling down, and wash with deionized water until the pH value is about 6;

(8) Put it in an oven at 105°C for 7 hours, then put it in a muffle furnace and bake it at 450°C for 3 hours. The La content is 0.89 (wt)%, and the ZrHZSM-5 molecular sieve is 99.11wt %.

Example 3

(1) First, the ZrHZSM-5 molecular sieve with nSiO ₂ /nAl ₂ O ₃ ratio of 131, Zr(wt)%: 2.15 was roasted at 540°C for 3 hours to remove the adsorbed impurities;

(2) 14.4 grams of molecular sieves treated in step (1) are mixed with 5.6 grams of pseudo-thin water alumina in a mortar and mixed, evenly ground;

(3) Add 2% nitric acid solution dropwise to the ground material and knead appropriately, extrude it into a columnar shape of Φ2 with a manual screw extruder, put it in an oven and dry it at 115°C;

(4) Then crush strip molecular sieves to 10-40 mesh, put them in a muffle furnace and heat up to 520 ° C for 3 hours to remove nitric acid and moisture, and take them out when the temperature drops below 60 ° C;

(5) Accurately weigh 4.0 grams of 98% sulfuric acid and put it into a volumetric flask, add deionized water to 200ml and be mixed with 0.2mol solution J; then weigh 6.04 grams of lanthanum nitrate and add it into solution _Y3 , and stir until it becomes until it is a colorless and transparent liquid;

(6) Weigh 10 grams of the molecular sieve prepared in step (4) and put it into the Erlenmeyer flask, add 180ml of solution Y ₃ , and maintain it at 60°C for 2 hours on the electromagnetic stirring heater;

(7) Filter the solution after cooling down, and wash with deionized water until the pH value is about 7;

(8) Put it into an oven at 120° C. for 8 hours, then put it into a muffle furnace and bake it at 240° C. for 5 hours to prepare the catalyst. Its La content was 1.34 (wt)%. ZrHZSM-5 molecular sieve is 98.66wt%.

Example 4

(1) At first 20 grams of nSiO ₂ /nAl ₂ O ₃ ratio is 192, Zr(wt)%: 1.89 ZrHZSM-5 molecular sieve is roasted at 540 ℃ for 3 hours to remove its adsorbed impurities;

(2) Combine 12.8 grams of molecular sieve treated in step (1) with 7.2 grams of γ-Al ₂ O ₃ . At the same time, put it into the mortar and mix it, and grind it evenly;

(3) Add 3% nitric acid solution dropwise to the ground material and knead properly, extrude it into a columnar shape of Φ2 with a manual screw extruder, put it in an oven and dry it at 120°C;

(4) Then crush strip molecular sieves to 10-40 mesh, put them in a muffle furnace and heat up to 520 ° C for 3 hours to remove nitric acid and moisture, and take them out when the temperature drops below 60 ° C;

(5) Accurately weigh 4.6 grams of 85% phosphoric acid and put it into a volumetric flask, add deionized water to _200ml and be mixed with _0.2mol solution Y until it becomes a colorless transparent liquid;

(6) Weigh 10 grams of molecular sieve prepared in step (4) and put it into an Erlenmeyer flask, add 180ml of solution Y ₄ , and maintain it at 80°C for 2 hours on an electromagnetic stirring heater;

(7) Filter the solution after cooling down, and wash with deionized water until the pH value is about 7;

(8) Put it into an oven at 120° C. for 6 hours, then put it into a muffle furnace and bake it at 200° C. for 3 hours to obtain a catalyst. The La content is 2.01 (wt), and the ZrHZSM-5 molecular sieve is 97.99 wt%.

Example 5

(1) at first 20 grams of nSiO ₂ /nAl ₂ O ₃ ratio is 135, Zr(wt)%: ZrHZSM-5 molecular sieve of 2.83 is roasted at 540 ℃ for 3 hours to remove its adsorbed impurities;

(2) Combine 12.8 grams of molecular sieve treated in step (1) with 7.2 grams of γ-Al ₂ O ₃ . At the same time, put it into the mortar and mix it, and grind it evenly;

(3) Add 3% nitric acid solution dropwise to the ground material and knead properly, extrude it into a columnar shape of Φ2 with a manual screw extruder, put it in an oven and dry it at 120°C;

(4) Then crush strip molecular sieves to 10-40 mesh, put them in a muffle furnace and heat up to 520 ° C for 3 hours to remove nitric acid and moisture, and take them out when the temperature drops below 60 ° C;

(5) Accurately weigh 4.6 grams of 85% phosphoric acid and put it into a volumetric flask, add deionized water to 200ml and be mixed with 0.2mol solution _Y5 ; then weigh 12.74 grams of lanthanum nitrate and add it into solution _Y5 , and stir until until it becomes a colorless transparent liquid;

(6) Weigh 10 grams of molecular sieve prepared in step (4) and put it into the Erlenmeyer flask, add 180ml of solution Y ₅ , and maintain it at 60°C for 2 hours on the electromagnetic stirring heater;

(7) Filter the solution after cooling down, and wash with deionized water until the pH value is about 7;

(8) Put it into an oven at 110° C. for 5 hours, then put it into a muffle furnace and bake it at 240° C. for 3 hours to obtain a catalyst. The La content is 2.83 (wt), and the ZrHZSM-5 molecular sieve is 97.17 wt%.

The acidic characterization of the catalyst prepared in the example was carried out by NH ₃ -TPD method, as shown in Table 1, it is obvious that at an appropriate content, the special properties of the rare earth element lanthanum can greatly improve the distribution of the acid active center of the catalyst, Greatly increase the total acid content of the catalyst and improve its reaction stability.

Table 1 Example La(wt)% Total acid amount mmol/g catalyst Example 1 0.52 0.558 Example 2 0.89 0.589 Example 3 1.34 0.665 Example 4 2.01 0.630 Example 5 2.83 0.591 Reference ratio 0 0.501

The catalyst prepared in the examples was evaluated on the reaction activity on a 2ml pressurized continuous flow fixed-bed reactor, and the reaction conditions were as follows: T=260° C. P=4.0Mpa mixed light hydrocarbons (composition (wt) %: propylene-31.90, Propane-14.01; n-, iso-butene-13.51; cis-, trans-butene-10.85; isobutane-18.34; n-butane-9.71) LHSV=2.0hr ^-1 , the product is collected in the ice condenser and taken out from the sampling bottle , was analyzed by Japan Shimadzu GC-7A hydrogen flame detector, and the chromatographic column was a 0.25×50-meter capillary column coated with OV1-101. The temperature was programmed from 30°C to 200°C at 2°C/min. The results of the reactions are shown in Table 2.

Table 2

Claims (7)

1. molecular sieve catalyst is characterized in that catalyst weight percentage consists of:

La：????????????????????????0.5-3.0

ZrHZSM-5 molecular sieve: 97.0-99.5.

2. a kind of molecular sieve catalyst as claimed in claim 1 is characterized in that described ZrHZSM-5 molecular sieve is nSiO ₂/ nAl ₂O ₃Be 20-200, Zr is 0.5-3.0wt% at the content of molecular sieve.

3. the preparation method of a kind of molecular sieve catalyst as claimed in claim 1 or 2 is characterized in that comprising the steps:

(1) silicon source, sodium salt and deionized water are mixed with A solution; With aluminium source, acid and deionized water in molar ratio for being mixed with B solution; Zirconium source, deionized water are mixed with C solution, under vigorous stirring, the B drips of solution is added in the A solution, add organic formwork agent then, add solution C again, stirring mixes it, aging, crystallization, Separation of Solid and Liquid, to obtaining molecular screen primary powder after filtration cakes torrefaction, the roasting, with the exchange of HCL solution, can obtain nSiO again through roasting ₂/ nAl ₂O ₃Than being that 20-200, Zr content are the ZrHZSM-5 molecular sieve of 0.5-3.0wt%, detailed preparation method sees that number of patent application is 03124261.8 a kind of synthetic fast synthetic method that contains zirconium atom ZSM-5 molecular sieve;

(2) with (1) step the ZrHZSM-5 molecular sieve at 520-540 ℃ of following roasting 3-5 hour to remove the impurity of its physical absorption;

(3) molecular sieve after the processing of (2) step is mixed with the part by weight of auxiliary agent by 63-72: 28-37, evenly grind;

(4) drips of solution that nitric acid is mixed with 2-4% adds to mix in the ground material of (3) step and pinches suitable back extrusion modling, 100-120 ℃ of oven dry down;

(5) material after the oven dry of (4) step is crushed to the 10-40 order, then at 500-520 ℃ of roasting 3-5 hour, to take off nitric acid and moisture;

(6) inorganic acid is mixed with the solution of 0.1-0.5mol concentration;

(7) again lanthanum salt and above-mentioned inorganic acid solution are mixed with the ion-exchange upgrading liquid Y that the concentration of lanthanum in solution is 0.1-0.5mol;

(8) under 20-80 ℃ electromagnetic agitation, carry out 1-3 hour ion-exchange in catalyst weight 1 gram with the ratio of 6-8ml ion exchange liquid;

(9) then solution is filtered be washed till the pH value and be 6-7 with deionized water after, it was kept in 100-120 ℃ baking oven 3-8 hour, made catalyst then at 300-500 ℃ of roasting 3-5 hour.

4. the preparation method of a kind of molecular sieve catalyst as claimed in claim 3 is characterized in that described lanthanum salt is the salt of water-soluble or diluted acid.

5. the preparation method of a kind of molecular sieve catalyst as claimed in claim 4 is characterized in that described lanthanum salt is lanthanum nitrate, lanthanum acetate, lanthanum sulfate.

6. the preparation method of a kind of molecular sieve catalyst as claimed in claim 3 is characterized in that described inorganic acid is nitric acid, sulfuric acid or hydrochloric acid.

7. the preparation method of a kind of molecular sieve catalyst as claimed in claim 3 is characterized in that described auxiliary agent is gama-alumina, thin water aluminium oxide or diatomite.