Preparation method of catalyst for acrylic acid by oxidizing acraldehyde

A catalyst, acrylic acid technology, applied in the field of catalysis, can solve the problems of catalyst activity and selectivity decline, sublimation, and difficulty in increasing catalyst reaction space velocity

Active Publication Date: 2011-05-04
CHINA NAT OFFSHORE OIL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The production of acrylic acid through the oxidation of acrolein has a higher yield and lower greenhouse gas emissions. At present, 90% of oxidation devices use this process, but there are two common problems: one is that the oxidation catalyst has a relatively long service life. Big defect, the current published patent (JP-B-57-54,172) claims that the acrylic acid catalyst has a service life of 4-6 years, but these traditional catalysts have been used in industrial production for several years, and none of them have stable catalytic performance. performance is completely satisfactory; in addition, the reaction space velocity of the catalyst is difficult to increase. Under high load conditions, the temperature of the catalyst bed rises sharply to generate hot spots, which then sublimate the active components in the catalyst, resulting in a decrease in catalytic activity. Therefore , for the tube-and-tube reactor where the oxidation reaction occurs, the production of acrylic acid can only be increased by increasing the size of the reactor
The spherical catalyst produced by the coating process is affected by the molding process, and the specific surface loss of the catalyst is large, resulting in a decrease in the activity and selectivity of the catalyst.

Method used

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  • Preparation method of catalyst for acrylic acid by oxidizing acraldehyde

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] (Preparation of composite oxide catalyst)

[0033] First, heat 5L of pure water to 95°C, add 451.7g of ammonium metatungstate to it, then add 253g of ammonium metavanadate and 916.7g of ammonium metamolybdate in turn, and dissolve it under stirring to obtain an orange transparent solution; After cooling the solution below 40°C, add 1.5L of ethanol and stir at high speed to form a uniform solution; then add 64.4g of antimony acetate to the above solution to form a black aqueous dispersion; then, dissolve 129.7g of copper sulfate in 833g of pure water, Mix with the above black dispersion to obtain a slurry, which is refluxed at 95°C for 2 hours; after that, add ethanol at a rate of 20ml / min, and simultaneously separate water in the system by distillation. When the ethanol content in the distillate is detected to be not less than 95%, the slurry is spray-dried, the nozzle temperature is controlled at 140°C, the feeding speed is adjusted to keep the outlet temperature at ab...

Embodiment 2

[0039] (Preparation of composite oxide catalyst)

[0040] Except that the add-on of copper sulfate is changed into 648.5g, and the add-on of antimony acetate is 12.88g, other preparation processes are all consistent with embodiment 1. The catalyst calculated from the charged raw materials was a composite oxide having the following atomic ratio.

[0041] Mo:V:W:Cu:Sb=12:5:4:6:0.1

[0042] (oxidation reaction)

[0043] 100ml of the prepared catalyst is packed into a stainless steel reaction tube with an internal diameter of 25ml, and the feed gas consisting of 6.5% concentration of acrolein, 8.5% concentration of oxygen, 52% concentration of nitrogen, and 33% concentration of water vapor is passed into it. At a pressure of 0.2MPa, the gas volume space velocity is 1800hr -1 acrolein oxidation reaction. The reaction results shown in Table 1 were obtained at a reaction temperature of 250°C.

Embodiment 3

[0045] (Preparation of composite oxide catalyst)

[0046] Except that the addition of ammonium metatungstate was changed to 135.5g and the addition of ammonium metavanadate was 151.8g, other preparation processes were consistent with Example 1. The catalyst calculated from the charged raw materials was a composite oxide having the following atomic ratio.

[0047] Mo:V:W:Cu:Sb=12:3:1.2:1.2:0.5

[0048] (oxidation reaction)

[0049] 100ml of the prepared catalyst is packed into a stainless steel reaction tube with an internal diameter of 25ml, and the feed gas consisting of 6.5% concentration of acrolein, 8.5% concentration of oxygen, 52% concentration of nitrogen, and 33% concentration of water vapor is passed into it. At a pressure of 0.2MPa, the gas volume space velocity is 1800hr -1 acrolein oxidation reaction. The reaction results shown in Table 1 were obtained at a reaction temperature of 250°C.

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Abstract

The invention relates to a preparation method of a catalyst for acrylic acid by oxidizing acraldehyde, which is characterized by comprising the following steps of: dispersing water soluble metal salts containing the components of Mo, V, W, Cu and Sb into a water/organic phase mixed system at the temperature of 30-100DEG C; maintaining the weight ratio of an organic solvent to water as 5-50 percent; reacting to generate composite oxide precursor serum; separating water by a distilling process under the condition of continuously supplementing organic phases at the temperature of 20-120DEG C, wherein the water content of distillate is not greater than 10 percent; then, pelleting by a spray drying process and roasting at the temperature of 200-600DEG C to prepare catalyst active components; mixing primary roasting powder, a forming additive and a strength improver; coating the active components on the surface of an inert carrier by using an adhesive, wherein the carrying capacity occupies5-70 percent of the total quantity of the catalyst; drying a formed product for 5-48 hours at room temperature; and then, roasting the formed product for 1-15 hours at the temperature of 200-600DEG Cto obtain a spherical catalyst with the active components carried on the inert carrier.

Description

Technical field: [0001] The invention relates to the technical field of catalysis, and relates to a preparation method of a catalyst for preparing acrylic acid by oxidizing acrolein. The gas-phase catalytic oxidation of acrolein is carried out by using gas containing molecular oxygen to generate acrylic acid with a relatively high yield. A method for preparing a catalyst with high stability and high selectivity in an impure water system is provided. Background of the invention: [0002] At present, the industrial production of acrylic acid mainly adopts a two-step oxidation method, the first step is the oxidation of propylene to acrolein, and the further oxidation of acrolein to acrylic acid. The production of acrylic acid through the oxidation of acrolein has a higher yield and lower greenhouse gas emissions. At present, 90% of oxidation devices use this process, but there are two common problems: one is that the oxidation catalyst has a relatively long service life. Big d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/888C07C57/055C07C51/235
Inventor 孙彦民曾贤君于海斌李晓云苗静李世鹏
Owner CHINA NAT OFFSHORE OIL CORP
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