Method for modifying iron-molybdenum catalyst for oxidizing methanol to formaldehyde

Abstract

The invention belongs to the field of industrial catalysis, and relates to a method for modifying an iron-molybdenum catalyst for oxidizing methanol to formaldehyde, in particular to a method for modifying an iron-molybdenum catalyst with a metal additive salt by the utilization of a mechanochemical method. By the utilization of a mechanochemical method, corresponding molybdate, iron salt and metal additive salt are firstly weighed according to a certain molar ratio of molybdenum: iron: metal additive; then, the metal additive salt is directly mixed with the solid-phase iron salt and molybdate, and the mixture undergoes ball-milling, drying and calcining to prepare the metal additive modified iron-molybdenum catalyst raw-powder. In the invention, the metal additive salt, the iron source and the molybdenum source undergo the mechanical milling process to prepare the iron-molybdenum catalyst. In comparison with a method without addition of metal salt, methanol conversion rate and formaldehyde selectivity are obviously improved by the above method of the invention. The method has simple process, and solvent water and other precipitators are not required. By the method, discharge of industrial wastewater can be greatly reduced, and manufacture cost of the catalyst is lowered.

Description

technical field [0001] The invention belongs to the field of industrial catalysis, and relates to a method for modifying an iron-molybdenum catalyst for methanol oxidation to formaldehyde, in particular to a method for modifying an iron-molybdenum catalyst using a mechanochemical method and a metal additive. Background technique [0002] Formaldehyde is a very important intermediate in the chemical industry. The world's annual output is about 30 million tons. It is an important downstream product of methanol. About 30% of methanol is used to produce formaldehyde (Green Chemistry, 2017, 19, 2347-2355). Formaldehyde is mainly used in the production of polyoxymethylene, 1,4-butanediol (BDO), resins, urotropine, preservatives, etc., and is widely used in the chemical industry, wood industry, and textile industries. [0003] Industrially, formaldehyde is produced by the oxidation method using methanol and air as raw materials. According to different catalysts, it is divided into ...

AI Technical Summary

Problems solved by technology

This method involves the use of relatively expensive template agents, and at the same time consumes a large amount of solvent water, resulting in industrial wastewater containing ammonium radicals, iron ions and other substances

[0006] In summary, industrially, iron-molybdenum catalysts are prepared by co-precipitation method, and the modification methods of iron-molybdenum catalysts also revolve around the co-precipitation method by adding various metal salts to the synthesis system. The production process of this method is complex and requires a large amount of solvent consumption. water, producing a large amount of industrial wastewater containing iron, molybdenum and ammonium salts, which has caused great pressure on environmental protection; secondly, the preparation of molecular sieve-supported iron-molybdenum catalysts involves the use of a large amount of expensive templates, which increases the cost of catalyst preparation; third, the current industry The formaldehyde selectivity of iron-molybdenum catalyst is about 92%, which needs to be further improved

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