A kind of ferromolybdenum catalyst with core-shell structure and its preparation and application

Abstract

The invention belongs to the field of carbon-chemical industry, and specifically relates to a core-shell structure ferromolybdenum catalyst and its preparation and application. The preparation process is as follows: preparing ferric nitrate solution, weighing dried molybdenum trioxide, completing the process of impregnating molybdenum carrier with iron-containing solution under the action of ultrasonic waves, and then drying, calcining and molding to obtain molybdenum-iron catalyst with core-shell structure. The method not only has simple process, few steps and short period, but also solves the problem of iron loss in the traditional method, and does not generate waste water in the preparation process. The ferromolybdenum catalyst with core-shell structure provided by the invention is composed of uniformly distributed and synergistic two-phase iron molybdate and molybdenum trioxide, and constitutes a core-shell structure in which an iron molybdate layer coats molybdenum trioxide particles microscopically. This structure effectively inhibits the volatilization and loss of molybdenum trioxide, ensures the stability of the catalyst element composition, physical structure, and physical and chemical properties, and exhibits excellent activity, selectivity, and stability when used in the oxidation of methanol to formaldehyde.

Description

technical field [0001] The invention belongs to the field of carbon-chemical industry, and relates to a novel structure ferromolybdenum catalytic material and its preparation and use, in particular to a core-shell structure ferromolybdenum catalyst prepared by an ultrasonic-assisted impregnation process and its use in methanol oxidation to produce high-concentration formaldehyde use in . Background technique [0002] my country is the world's largest producer and consumer of formaldehyde. In the future, with the further increase in the consumption of resins, paints, (polyoxymethylene) and other products and the rise of new products such as acrylic acid (ester) and polyoxymethylene dimethyl ether, my country's demand for high-concentration formaldehyde will increase day by day. As we all know, the iron-molybdenum process is an advanced process for the production of concentrated formaldehyde, but the ferro-molybdenum catalyst used in this process in my country relies heavily ...

AI Technical Summary

Problems solved by technology

Although the catalyst prepared by this method has good activity, due to the structural characteristics of the precipitated bulk catalyst, the molybdenum in it is easy to sublimate and lose, resulting in unstable physical structure and catalytic performance of the catalyst, and shortened service life. There are also problems such as iron ions cannot be completely precipitated and lost, the preparation steps and cycle are long, and more waste water is generated.

The sol-gel method is also a commonly used method to prepare the catalyst. There are also problems such as the molybdenum of the prepared catalyst is volatile and lost, the preparation steps and cycle are long, and the generation of waste water is large. At the same time, there are also problems such as washing, filtering and molding difficulties.

Although the solid-phase mixing method does not have the above-mentioned other problems, there is still the problem that the obtained catalyst molybdenum is easy to lose, and because mechanical mixing is a key step, the energy consumption of the catalyst preparation is high and the contact reaction between the phases cannot be fully contacted, resulting in its structure. relatively poor performance

[0004] The impregnation method is a simple and efficient catalyst preparation method, but so far, there is no information on the technology for preparing molybdenum-iron catalysts by this method

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