KR19990021570A - Preparation of Acrolein and Methacrolein Production Catalyst - Google Patents

Abstract

The present invention relates to a method for producing an oxide catalyst of molybdenum, bismuth, cobalt, iron, etc., in which propylene, secondary propanol and isobutylene or tertiary butanol are partially oxidized with oxygen in air to produce acrolein and methacrolein, respectively. The present invention provides a method for preparing a catalyst slurry having a solid content of 62 to 72% without decreasing the performance of the catalyst by decreasing the slurry temperature when preparing the catalyst slurry of the supersaturated solution of molybdenum.

Description

Preparation of Acrolein and Methacrolein Production Catalyst

The present invention relates to oxide catalysts such as molybdenum, bismuth, cobalt, iron and the like which are used in the reaction of partially oxidation of propylene and isobutylene with oxygen to produce acrolein and methacrolein as the main products, respectively.

The present invention also relates to an improved method for producing a catalyst and a method for producing acrolein and methacrolein using the catalyst.

In general, catalysts used for the partial oxidation of propylene and isobutylene are formed into pellets or tablets or various other shapes. The process of forming such catalysts is carried out through catalyst synthesis (catalyst slurry production) and drying. , Grinding, shaping and firing.

The present invention relates to a catalyst slurry preparation and drying process during such catalyst preparation. When preparing the catalyst slurry, the solvent (mostly water) that dissolves the metal salt is mostly evaporated during the drying process. In the prior art known to the art, it is known to prepare a catalyst slurry by dissolving each metal salt in an excess of water to form a metal salt solution and precipitating these metal salt solutions with each other. The catalyst slurry prepared by using a metal salt solution using excess water has a solid content of only about 30-50%, so that 50-70% of the water is evaporated during the drying process in proportion to the amount of water to be evaporated. It takes energy and time. For example, US Pat. No. 4,049,577 and US Pat. No. 4,129,600 produce catalyst slurries having a solids content of 44.6% at 90 ° C. and dry them at 100 ° C., while US Pat. A catalyst slurry of% was prepared. These catalysts have a low solids content in light of the new findings of the inventors (catalyst slurries degrade at high temperatures (above 40 ° C.) for long periods of time), resulting in longer solids at drying temperatures (more than 2 hours). ), And it takes a lot of energy to dry. Therefore, there has been a need for a method for reducing the amount of water evaporated during catalyst preparation.

In the present invention, the solid content is defined as follows for convenience.

Solids content = (gross weight of slurry-mass) / gross weight of slurry

In general, the catalyst slurry is cobalt nitrate (Co (NO ₃ ) ₃ .6H ₂ O), bismuth nitrate in a solution of ammonium para molybdate ([(NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O]) A mixed solution of (Bi (NO ₃ ) ₃ · 5H ₂ O), nickel nitrate (Ni (NO ₃ ) ₃ · 9H ₂ O), ferric nitrate (Fe (NO ₃ ) ₃ · 9H ₂ O), etc. The catalyst slurry is prepared by addition and precipitation.

The present inventors observed that when preparing a catalyst slurry, the amount of water and the addition of a solution such as cobalt, bismuth, iron, etc., resulted in the formation of precipitates, and the increase in the amount of the precipitates resulted in severe entanglement of the slurry. It was observed that the catalyst activity when the catalyst slurry was agglomerated was significantly lower than the catalyst activity when there was no agglomeration, and this slurry agglomeration was closely related to the amount of water. That is, when the catalyst slurry is prepared using a lot of water, no agglomeration phenomenon occurs, and when the catalyst slurry is prepared using less water, the agglomeration phenomenon becomes very severe and the performance of the catalyst is lowered. If less water is used, agglomeration occurs and the catalyst performance is lowered. Therefore, there is a limit to reducing the amount of water used when preparing the catalyst slurry. Therefore, a technique for maintaining catalyst performance while increasing energy efficiency by reducing the amount of water in preparing a catalyst slurry has been recognized as a goal of researchers.

The inventors have found that the slurry entanglement is closely related to the catalyst slurry temperature as well as the amount of catalyst used in the preparation of the catalyst slurry, thereby finding a method of maintaining the catalyst efficiency by reducing the amount of water and suppressing the entanglement. To complete. In other words, when the catalyst slurry is prepared at a high temperature, the slurry agglomeration is increased, and when the catalyst slurry is prepared at a low temperature, the agglomeration is hardly generated. Thus, the catalyst slurry is prepared by preparing the catalyst slurry using less water. The catalyst slurry with a high solid content could be manufactured by lowering slurry temperature in the inside. That is, by dropping the catalyst slurry temperature maintained at the first 40 ~ 90 ℃ to 40 ℃ or less while adding a solution of cobalt, nickel, bismuth, ferric, etc. to obtain a catalyst slurry having a solid content of 62 to 72% without entanglement Could be manufactured.

On the other hand, if the amount of water (less than water / ammonium para molybdate = 0.5 ~ 1.0 or less) at 40 ℃ or less is used, ammonium para molybdate is not completely dissolved. When the catalyst slurry was prepared by adding a cobalt, nickel, bismuth, and iron solution to a solution in which an ammonium para molybdate solution was dissolved and an undissolved ammonium para molybdate solution, it was confirmed that the catalyst performance was deteriorated. Therefore, it was found that the catalyst slurry should be prepared in a state in which ammonium para molybdate was completely dissolved.

Therefore, a solution of cobalt, nickel, bismuth, and ferric iron is added to an aqueous solution in which ammonium para molybdate is completely dissolved at 40 ° C. or higher, thereby reacting with ammonium para molybdate dissolved in the aqueous solution to form a precipitate. It is not related to precipitation. As a precipitate forms, the ammonium para molybdate in the aqueous solution is transferred onto the precipitate, leaving room for more ammonium para molybdate to be dissolved. From the point of view of solubility, the lowering of the temperature decreases the solubility of ammonium para molybdate, so precipitation should occur. There is a margin of so that reprecipitation does not occur and can continue to exist in the aqueous solution. Thus, even at a drop in temperature, ammonium para molybdate could continue to be present in the aqueous solution to prepare a catalyst slurry without performance loss. In addition, entanglement could be eliminated by lowering the temperature to prepare a catalyst slurry.

This catalyst slurry production method is a catalyst for converting propylene, secondary propanol, isobutylene or tert-butanol to acrolein and methacrolein to the main product, i.e., the following general formula (1)

MoaBibFecXdYeZfOg… (One)

It can be used when preparing a catalyst containing a composition represented by (wherein X is at least one element selected from Co and Ni, Y is 1 selected from Li, Na, K, Rb, Cs and Tl) Z is W, Be, Mg, S, Ca, Sr, Ba, Te, Se, Ce, Ge, Mn, Cr, Ag, Sb, Pb, As, B, P, Nb, Cu, Cd At least one element selected from among Sn, Al, Zr, Ti, and Si: a, b, c, d, e, f, g represent an atomic ratio of each element, and a is based on a When = 12, b = 0.1-20, c = 0.1-20, d = 0.52-20, e = 0.01-2, f = 0-10, g is an atom of oxygen necessary to satisfy the valence of each of the above components. Number).

The catalyst slurry prepared by reducing the amount of the material by the method of the present invention is shown in Example 1, and the slurry prepared by a conventional method is shown in Comparative Examples 1 and 2.

Example 1

760 g of ammonium para molybdate were dissolved while heating 600 g of water at 60 ° C (solution A). 420 g of cobalt nitrate was dissolved in 100 g of water (solution B). In a solution in which 150 g of ferric nitrate and 2.4 g of rubidium nitrate were dissolved in 100 g of water, 60 g of nitric acid and 170 g of bismuth nitrate were dissolved and mixed in 150 g of water (solution C). Then, 270 g of silica sol (solution D) is prepared.

Solution B and C were dropped simultaneously with vigorous stirring of solution A, and then solution D was added to prepare a catalyst slurry having a solid content of 65.9%. The catalyst slurry is entangled during the dropping of solutions B and C. At this time, the slurry temperature is dropped from 60 ° C. to 25 ° C. (slurry entanglement occurs when the solution B and C is about 1/3 added). The prepared catalyst slurry was dried in an oven at 120 ° C., dried, and the dried catalyst cake was pulverized into fine powder, and pellets having a diameter of 6.0 mm and a length of 6 mm were formed by using an extruder by adding an appropriate amount of water. The formed pellets were calcined at 450 ° C., and the metal atom composition of the obtained catalyst was shown in the following equation (2).

Mo ₁₂ Co ₄ Bi ₁ Fe ₁ Rb _0.04 Si ₅ . (2)

The catalyst obtained was filled in a steel reaction tube with an inner diameter of 15 mm, and a mixture gas of 6.5% by volume of propylene, 11.7% by volume of oxygen, 71.8% by volume of nitrogen, and 10.0% by volume of water vapor was flowed at a space velocity of 1350 hr < -1 > The reaction was carried out while maintaining at 占 폚.

The reaction resulted in 96.8% propylene conversion, 89.3% acrolein selectivity, and 6.3 acrylic acid selectivity, yielding 92.5% acrolein + acrylic acid.

Comparative Example 1

760 g of ammonium para molybdate were dissolved while heating 2500 g of water at 60 ° C. (solution A). 420 g of cobalt nitrate was dissolved in 200 g of water (solution B). In a solution in which 150 g of ferric nitrate and 2.4 g of rubidium nitrate were dissolved in 100 g of water, 60 g of nitric acid and 170 g of bismuth nitrate were dissolved and mixed in 150 g of water (solution C). Then, 270 g of silica sol (solution D) is prepared.

Solution B and C were simultaneously dropped while vigorously stirring solution A, and then solution D was added to prepare a catalyst slurry having a solids content of 39.1%. The prepared catalyst slurry was dried in an oven at 120 ° C., dried, and the dried catalyst cake was pulverized into fine powder, and pellets having a diameter of 6.0 mm and a length of 6 mm were formed by using an extruder by adding an appropriate amount of water. The formed pellets were calcined at 450 ° C., and the metal atom composition of the obtained catalyst was the same as in Example 1, and the reaction conditions and the reaction apparatus were the same as in Example 1.

As a result of the reaction, the yield of acrolein and acrylic acid was 92.6% with a propylene conversion of 97.0%, an acrolein selectivity of 89.5% and an acrylic acid selectivity of 6.0.

Comparative Example 2

760 g of ammonium para molybdate were dissolved while heating 600 g of water at 60 ° C (solution A). 420 g of cobalt nitrate was dissolved in 100 g of water (solution B). In a solution in which 150 g of ferric nitrate and 2.4 g of rubidium nitrate were dissolved in 100 g of water, 60 g of nitric acid and 170 g of bismuth nitrate were dissolved and mixed in 150 g of water (solution C). Then, 270 g of silica sol (solution D) is prepared.

Solution B and C were simultaneously dropped while vigorously stirring Solution A, then Solution D was added to produce a catalyst slurry with a solid content of 65.9% (catalyst slurry was entangled while dropping Solution B and C). The prepared catalyst slurry was dried in an oven at 120 ° C., dried, and the dried catalyst cake was pulverized into fine powder, and pellets having a diameter of 6.0 mm and a length of 6 mm were formed by using an extruder by adding an appropriate amount of water. The formed pellets were calcined at 450 ° C., and the metal atom composition of the obtained catalyst was the same as in Example 1.

The reaction conditions and the reaction apparatus were the same as in Example 1.

As a result, acrolein + acrylic acid yield was 86.8%, acrolein selectivity 92.8%, and acrylic acid selectivity 4.3, yielding 84.3%.

The present invention was able to reduce the energy consumed in the drying process by increasing the solid content as much as possible by reducing the amount of water without reducing the catalyst performance as shown in Example 1, Comparative Example 1, Comparative Example 2.

Claims (7)

General formula below (1) MoaBibFecXdYeZfOg… (One) In preparing a catalyst for the oxidation of propylene, secondary protanol, isobutylene and tertiary butanol, the solution of cobalt, bismuth, nickel, after preparing an aqueous solution in which ammonium para molybdate is completely dissolved at a temperature Process for preparing a catalyst slurry by lowering the temperature to 0-40 ° C. while adding ferric solution: In the above formula X is at least one element selected from Co and Ni, Y is at least one member selected from Li, Na, K, Rb, Cs and Tl Cow, Z is W, Be, Mg, S, Ca, Sr, Ba, Te, Se, Ce, Ge, Mn, Cr, Ag, Sb, Choose from Pb, As, B, P, Nb, Cu, Cd, Sn, Al, Zr, Ti and Si 1 kind More than one element is represented; a, b, c, d, e, f, g represent the atomic ratios of each element, based on a When b = 0.1 to 20, c = 0.1 to 20, d = 0.52 to 20, e = 0.01-2, f = 0-10, and g is required to satisfy the valence of each of the above components. It is the number of atoms of oxygen. The process of claim 1 wherein the solids content of the catalyst slurry is 62-72 weight percent. The process according to claim 1, wherein the temperature of ammonium para molybdate is 40 to 92 ° C. The method of claim 1, wherein the weight slurry of water: ammonium para molybdate in an aqueous solution of ammonium para molybdate is 0.5 to 1.0. Preparing an aqueous solution in which ammonium para molybdate is completely dissolved at a temperature of 40 ° C. or higher; And Adding a cobalt, bismuth, nickel and ferric solution to lower the temperature to 40 ° C. or lower; Method for producing acrolein and methacrolein production catalyst represented by the following general formula (1) having a solid content of 62 to 72% containing: MoaBibFecXdYeZfOg… (One) In the above formula X is at least one element selected from Co and Ni, Y is at least one member selected from Li, Na, K, Rb, Cs and Tl Cow, Z is W, Be, Mg, S, Ca, Sr, Ba, Te, Se, Ce, Ge, Mn, Cr, Ag, Sb, Choose from Pb, As, B, P, Nb, Cu, Cd, Sn, Al, Zr, Ti and Si 1 kind More than one element is represented; a, b, c, d, e, f, g represent the atomic ratios of each element, based on a When b = 0.1 to 20, c = 0.1 to 20, d = 0.52 to 20, e = 0.01-2, f = 0-10, and g is required to satisfy the valence of each of the above components. It is the number of atoms of oxygen. A catalyst prepared by the method of claim 1. A method for producing acrorea and methacrolein using the catalyst prepared by the method of claim 1.