CN1120750C - Catalyst for synthesizing methyl isobutyl ketone and preparation process thereof - Google Patents

Abstract

A catalyst for synthesizing methyl isobutyl ketone and a preparation method thereof. The weight percent composition of the catalyst is: Pd: 0.051-0.750%, ZSM-5 molecular sieve: 99.250-99.949%. The invention integrates three catalytic functions of acetone condensation, dehydration and hydrogenation, greatly simplifies the existing reaction process, not only reduces production cost, but also increases operability; the catalyst has high selectivity and simplifies the product separation step.

Description

Catalyst for synthesizing methyl isobutyl ketone and preparation method thereof

Technical field:

The invention belongs to a catalyst for synthesizing methyl isobutyl ketone and a preparation method thereof, in particular to a ZSM-5 catalyst for synthesizing methyl isobutyl ketone and a preparation method thereof.

Background technique:

Methyl isobutyl ketone (MIBK) is a fine organic chemical product with excellent performance and wide application. It is not only used in the production of organic solvents such as inks, paints, and epoxy resins, but also used in large quantities as antioxidants and isoflurane, etc. Organic synthesis intermediates. In recent years, with the continuous expansion of the application field, the demand at home and abroad has been increasing, so it is of great significance to research and develop new synthetic process routes.

At present, the traditional three-step method is still used in the industrial production of MIBK, that is, acetone is condensed under alkali catalysis to obtain dipropanol ketone, and then dipropanol ketone is dehydrated under acid catalysis to generate mesityl oxide, and then in nickel or copper system Action and hydrogenation under medium pressure finally give MIBK. The technological process is complicated, the production cycle is long, the cost is high and the energy consumption is large, so it lacks competitiveness.

In recent years, more and more attention has been paid to the research on the one-step synthesis of MIBK from acetone. This method integrates the three steps of acetone condensation, dehydration and hydrogenation in one reactor. It has the advantages of short process flow, low investment and low production cost. It represents the development direction of MIBK production technology and has broad application prospects.

But the technology of one-step synthetic MIBK also has its weak point, mainly shows in acetone one-pass conversion rate and MIBK selectivity low two aspects, as Wu Huixing etc. published a kind of one-step in " molecular sieve communication " (1993 (2) 5) Method for synthesizing MIBK. The method uses Ni-loaded basic zeolite, Pd-loaded transformed Y zeolite or Pd ZSM-5 as catalysts, and under the conditions of T=180-260°C and P=2.0-4.0Mpa, acetone is condensed, dehydrated, and hydrogenated to synthesize MIBK in one step. , the single-pass conversion of acetone is 41.8%, and the MIBK selectivity is 82.4%.

Invention content:

The purpose of the present invention is to provide a catalyst for synthesizing methyl isobutyl ketone with high selectivity and high conversion rate and its preparation method.

Catalyst weight percent of the present invention consists of:

Pd 0.051～0.750%

ZSM-5 molecular sieve 99.250～99.949%

The above-mentioned ZSM-5 molecular sieve is made by mixing the hydrogen ZSM-5 molecular sieve with a Si/Al molar ratio of 28-70 and additives selected from pseudo-thin water alumina or γ-Al ₂ O ₃ .

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

(1) First, the hydrogen-type ZSM-5 molecular sieve with Si/Al (mol) of 28-70 is roasted at 520-540° C. for 3-5 hours to remove the physically adsorbed impurities;

(2) Mix the molecular sieve after the step (1) with the auxiliary agent in a ratio of 72 to 63: 28 to 37 by weight, and grind evenly;

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

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

(5) PdCl ₂ is made into a solution with a molar concentration of 0.01 to 0.08 with deionized water, and it is necessary to add a solvent in an amount of not less than 1.5ml per gram of molecular sieve, stir evenly, and make an impregnating solution, which is composed of Pd according to the weight percentage of the catalyst. : 0.051～0.750%; ZSM-5 molecular sieve: 99.250～99.949%, immerse the ZSM-5 molecular sieve prepared in step (4) in the soaking solution for 3-6 hours, and stir once every 1-2 hours;

(6) drying the impregnated ZSM-5 molecular sieve at 100-120° C. for 10-12 hours, and then calcining at 200-250° C. for 3-4 hours to prepare the catalyst.

The additive mentioned above is pseudo-alumina or γ-Al ₂ O ₃ .

The solvents mentioned above are acetone or ethanol.

The advantages of the present invention are:

(1) It integrates three catalytic functions of acetone condensation, dehydration and hydrogenation, which greatly simplifies the existing reaction process, reduces production costs and increases operability.

(2) The selectivity of the catalyst is high, which can be increased by more than 15% compared with the result in the literature, so the product separation step can be simplified.

Detailed ways:

Example 1

(1) at first 20 grams of Si/Al (mol) is the hydrogen type ZSM-5 molecular sieve of 28 at 540 ℃ for 3 hours to remove the impurity that it adsorbs;

(2) 13 grams of molecular sieves and 7 grams of γ-Al ₂ O ₃ are simultaneously put into a mortar and mixed, and ground evenly;

(3) Add 3% nitric acid solution dropwise to the ground material and knead properly, press it into a Φ2 columnar shape 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 5 hours to remove nitric acid and moisture, and take them out when the temperature drops below 60 ° C;

(5) PdCl ₂ is prepared with deionized water into a 0.01mol PdCl ₂ solution, shake well and set aside;

(6) When the prepared Pd content is 0.08%, put 1.58ml _of PdCl solution into a beaker with 18.43ml of acetone and stir evenly, then impregnate 10 grams of molecular sieves therein for 5 hours, and stir once every 1 hour;

(7) Put it into an oven at 120° C. for 10 to 12 hours, then put it into a muffle furnace and bake it at 200° C. for 3 hours to prepare the catalyst.

Example 2

(1) at first 20 grams of Si/Al (mol) is the hydrogen type ZSM-5 molecular sieve of 35.3 roasting at 540 ℃ for 3 hours to remove its adsorbed impurities;

(2) 14 grams of molecular sieves and 6 grams of γ-Al ₂ O ₃ are simultaneously put into a mortar and mixed, and ground evenly;

(3) Add 3% nitric acid solution dropwise to the ground material and knead properly, press it into a Φ2 columnar shape 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) PdCl ₂ is prepared into 0.05mol PdCl ₂ solution with deionized water, shake well and set aside;

(6) When the prepared Pd content is 0.25%, put 0.98ml _of PdCl solution into the beaker with 19.02ml of acetone and stir evenly, then impregnate 10 grams of molecular sieves therein for 3 hours, and stir once every 1 hour;

(7) Put it into an oven at 120° C. for 10 hours, then put it into a muffle furnace and bake it at 200° C. for 3 hours to prepare the catalyst.

Example 3

(1) at first 20 grams of Si/Al (mol) is the hydrogen type ZSM-5 molecular sieve of 35.3 roasting at 540 ℃ for 3 hours to remove its adsorbed impurities;

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

(3) Add 2% nitric acid solution dropwise to the ground material and knead properly, press 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) PdCl ₂ is prepared with deionized water into 0.10mol PdCl ₂ solution, shake well and set aside;

(6) When the prepared Pd content is 0.45%, put 0.90ml _of PdCl solution into the beaker with 19.11ml of acetone and stir evenly, then impregnate 10 grams of molecular sieves therein for 8 hours, and stir once every 2 hours;

(7) Put it into an oven at 120° C. for 10 hours, then put it into a muffle furnace and bake it at 230° C. for 3 hours to prepare the catalyst.

Example 4

(1) at first 20 grams of Si/Al (mol) is the hydrogen type ZSM-5 molecular sieve of 67.8 at 540 ℃ for 3 hours to remove the impurity that it adsorbs;

(2) 12.8 grams of molecular sieves are mixed with 7.2 grams of γ-Al ₂ O ₃ in a mortar and ground evenly;

(3) Add 3% nitric acid solution dropwise to the ground material and knead properly, press it into a Φ2 columnar shape 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) PdCl ₂ is prepared with deionized water into 0.10mol PdCl ₂ solution, shake well and set aside;

(6) When the prepared Pd content was 0.65%, 1.29ml _of PdCl solution was added into a beaker with 18.72ml of ethanol and stirred evenly, then 10 grams of molecular sieves were impregnated therein for 4 hours, and stirred once every 1 hour;

(7) Put it into an oven at 120° C. for 10 to 12 hours, then put it into a muffle furnace and bake it at 200° C. for 3 hours to prepare the catalyst.

Example 5

(1) at first with 20 grams of Si/Al (mol) be the hydrogen type ZSM-5 molecular sieve of 52.5 at 540 ℃ for 3 hours to remove the impurity that it adsorbs;

(2) 12.8 grams of molecular sieves are mixed with 7.2 grams of γ-Al ₂ O ₃ in a mortar, and uniformly ground;

(3) Add 3% nitric acid solution dropwise to the ground material and knead properly, press it into a Φ2 columnar shape 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) PdCl ₂ is prepared into 0.05mol PdCl ₂ solution with deionized water, shake well and set aside;

(6) When the prepared Pd content is 0.65%, put 2.96ml _of PdCl solution and 17.05ml of acetone into the beaker and stir evenly, then impregnate 10 grams of molecular sieves therein for 6 hours, and stir once every 1 hour;

(7) Put it into an oven at 110° C. for 8 hours, then put it into a muffle furnace and bake it at 240° C. for 3 hours to prepare the catalyst.

Catalyst performance characterization and reactivity determination: NH3-TPD was used to measure the variation of strong and weak acids of different molecular sieves, see Table 1. Table 1

Catalyst evaluation: react with different contents of PdZSM-5 on a 2ml pressurized fixed reaction device, the conditions are as follows: T=220°C, P=2.5Mpa, LHSV=1.5hr ^-1 , the product is collected and condensed in an ice condenser Afterwards, it was taken out from the sampling bottle, and analyzed by a Japanese Shimadzu GC-7A hydrogen flame detector, and the chromatographic column was a polyethylene glycol 30-meter capillary column. The reaction results are shown in Table 2. Table 2

Claims (3)

1. A catalyst for synthesizing methyl isobutyl ketone, characterized in that the weight percentage of the catalyst is composed of: Pd: 0.051～0.750% ZSM-5 molecular sieve: 99.250～99.949%; The ZSM-5 molecular sieve is made by mixing the hydrogen ZSM-5 molecular sieve with a Si/Al molar ratio of 28-70 and additives selected from pseudo-thin water alumina or γ-Al ₂ O ₃ . 2. a kind of preparation method of synthetic methyl isobutyl ketone catalyst as claimed in claim 1, is characterized in that the preparation method of catalyst comprises the steps: (1) First, the hydrogen-type ZSM-5 molecular sieve with Si/Al (mol) of 28-70 is roasted at 520-540° C. for 3-5 hours to remove the physically adsorbed impurities; (2) Mix the molecular sieve after the step (1) with the auxiliary agent in a ratio of 72 to 63: 28 to 37 by weight, and grind evenly; (3) Add nitric acid to a solution of 2-4% dropwise into the material ground in step (2), knead properly, extrude, and dry at 100-120°C; (4) Pulverize the dried material in step (3) to 10-40 meshes, then roast at 500-520° C. for 3-5 hours to remove nitric acid and moisture; (5) PdCl ₂ is made into a solution with a molar concentration of 0.01 to 0.08 with deionized water, and it is necessary to add a solvent in an amount of not less than 1.5ml per gram of molecular sieve, stir evenly, and make an impregnating solution, which is composed of Pd according to the weight percentage of the catalyst. : 0.051～0.750%; ZSM-5 molecular sieve: 99.250～99.949%, immerse the ZSM-5 molecular sieve prepared in step (4) in the soaking solution for 3-6 hours, and stir once every 1-2 hours; (6) drying the impregnated ZSM-5 molecular sieve at 100-120° C. for 10-12 hours, and then calcining at 200-250° C. for 3-4 hours to prepare the catalyst. 3. a kind of preparation method of synthetic methyl isobutyl ketone catalyst as claimed in claim 2 is characterized in that described solvent is acetone or ethanol.