Anhydrous production method of DMMn (polyoxymethylene dimethyl ethers)

Abstract

The invention discloses an anhydrous production method of DMMn (polyoxymethylene dimethyl ethers). The anhydrous production method comprises steps as follows: a substance containing hydrogen sulfate radicals is taken as a catalyst, at least dimethoxymethane and paraformaldehyde are taken as reaction raw materials, the catalyst and the raw materials are subjected to a reaction at the temperature of 70-150 DEG C and under the pressure of 0.1-8.0 MPa, and DMMn is prepared. Preferably, the catalyst accounts for 0.5wt%-30wt% of the total reaction materials, and further preferably, the catalyst accounts for 1wt%-10wt% of the total reaction materials. The protection process of DMMn adopts paraformaldehyde as an aldehyde source, the cost is low, meanwhile, low-cost hydrogen sulfate or supported hydrogen sulfate is taken as the catalyst, the catalyst has a good effect and is non-toxic and low in cost, and particularly, compared with strong acids such as sulfuric acid, hydrochloric acid and the like, low-cost hydrogen sulfate or supported hydrogen sulfate has relatively lower acidity, is in a solid state, has low corrosivity and can be recycled from a reaction system through simple filtration.

Description

technical field [0001] The invention relates to a production process of polyoxymethylene dimethyl ether, in particular to a process for continuously producing polyoxymethylene dimethyl ether in an anhydrous system, which uses a hydrogen sulfate-containing catalyst to catalyze paraformaldehyde and methylation Aldehyde reaction to produce polyoxymethylene dimethyl ether. Background technique [0002] Polyoxymethylene dimethyl ether (DMMn) has a higher cetane number, usually above 63, such as: DMM2 63, DMM3 78, DMM4 90, DMM5 100, and its oxygen content is higher, which can improve combustion efficiency. Reduce the emission of particulate matter, NOx and hydrocarbon VOC in exhaust gas; polyoxyl dimethyl ether has good blending performance with diesel, can be miscible, and has self-lubricating property, which can prolong the life of diesel machinery. It is an ideal diesel additive [0003] At present, there are many kinds of production techniques for polyoxymethylene dimethyl et...

AI Technical Summary

Problems solved by technology

However, when liquid acids such as sulfuric acid and hydrochloric acid are used as catalysts, the equipment is corroded more seriously, and it is difficult to separate from the product in the later stage; 4 2- / TiO 2 When using a solid superacid as a catalyst, if paraformaldehyde is used as a raw material, the reaction activity of the solid superacid is poor and the conversion rate is very low; while using an ionic liquid as a catalyst, although there are many advantages such as easy separation of products and good selectivity, but The relative price is also slightly higher

[0007] In summary, there are still many defects in the process of producing polyoxymethylene dimethyl ether from paraformaldehyde in the current anhydrous system, which needs to be improved urgently

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