Method for preparing polyformaldehyde dimethyl ether by using loaded niobium oxide catalyst

Abstract

The invention relates to a method for preparing polyformaldehyde dimethyl ether by using a loaded niobium oxide catalyst. The method is characterized by comprising the following steps of: a) preparing the polyformaldehyde dimethyl ether by a catalytic reaction, wherein the molar ratio of methylal to trioxymethylene is 0.5 to 5, loaded niobium oxide is taken as a catalyst, the using amount of the catalyst is 0.1 to 5 percent of the molar weight of a reactant, the reaction temperature is between 100 and 200 DEG C, reaction time is between 10 minutes and 48 hours and reaction pressure is between 0.1 and 10 MPa; b) rectifying and separating, namely, separating a low-boiling point component, namely, methylal DMM, polydiformaldehyde dimethyl ether DMM2 and unreacted trioxymethylene out and separating polyformaldehyde diformaldehyde DMM3-8 out, wherein a small amount of polyformaldehyde dimethyl ether DMMn with a high polymerization degree exists at the bottom of a kettle and n is more than 8; and c) adding a small amount of fresh trioxymethylene into the methylal, the polydiformaldehyde dimethyl ether DMM2 and the unreacted trioxymethylene which are separated out in the previous step and continuing reacting so as to obtain the polyformaldehyde diformaldehyde DMM3-8 which is suitable to be taken as a diesel engine blending combustion component. Therefore, the utilization ratios of raw materials are increased.

Description

Technical field:

[0001] The invention relates to the technical field of fine chemical synthesis, and is a method for preparing polyoxymethylene dimethyl ether with a supported niobium oxide catalyst. Formaldehyde dimethyl ether method. Background of the invention:

[0002] In recent decades, with the increasingly severe energy crisis and increasing oil consumption, and due to environmental protection requirements to use ultra-clean diesel, the development of many new alternative diesels that can reduce pollutant emissions has emerged. Among them, the use of diesel Blending components without adding additional devices or changing the engine structure is considered to be a convenient and effective measure. To reduce the formation of soot and soot during the combustion of conventional diesel fuel, oxygenated compounds containing only few, if any, carbon-carbon bonds, such as methanol, are added, but such compounds are often insoluble in diesel and reduce the sixteen Alkanes a...

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