Method for preparation of polyoxymethylene dimethyl ether from paraformaldehyde
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A technology of polyoxymethylene dimethyl ether and paraformaldehyde, which is applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve the problems of reducing the proportion of products, polluting the environment, and complex separation.
Inactive Publication Date: 2013-03-13
CHINA NAT OFFSHORE OIL CORP +1
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Problems solved by technology
[0014] The technical problem to be solved in the present invention is to overcome the problems in previous reports that the process of preparing polyoxymethylene dimethyl ether is complicated, the liquid acid catalyst used corrodes equipment, pollutes the environment, the separation is complicated, the production cost is high, or the stability and activity cannot be balanced. Considering the economy, use cheaper paraformaldehyde to replace the expensive paraformaldehyde used in some patents. At the same time, use methylal instead of methanol to provide the methoxy part, reduce the proportion of water in the product, and simplify the subsequent separation process , providing a method for preparing polyoxymethylene dimethyl ether by catalyzing the reaction of methylal and paraformaldehyde with modified acidic resin, and providing a further method for separating and purifying polyoxymethylene dimethyl ether
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Embodiment 1
[0030] Add in a 2L autoclave, add 800 g methylal and 400 g paraformaldehyde, 12 g Amberlyst 15 cation exchange resin in sequence, fill with nitrogen to a pressure of 3 MPa, heat to 90 ° C, and stir at a speed of 192 rpm. Samples were taken at 1, 2, 4, 6, 8, 10, and 12 hr and analyzed by gas chromatography. The chromatographic detection results show that the equilibrium composition is obtained after 8 hours of reaction, wherein DMM 37.5%, MeOH 2.6%, DMM 2 24.1 %, DMM 3 14.1 %, DMM 4 8.4%, DMM 5 5.0%, DMM 6 2.1%, DMM 7 1.0%, DMM 8 0.5%, DMM n (n>8) not detected.
Embodiment 2
[0032] Add in a 2L autoclave, sequentially add 800 g methylal and 400 g paraformaldehyde, 24 g Amberlyst ER-124 cation exchange resin, fill with nitrogen to a pressure of 3 MPa, heat to 120°C, and stir at a speed of 192 rpm Reacted for 8 hr, analyzed by gas chromatography after filtering off the catalyst, wherein DMM 39.2%, MeOH 6.6%, DMM 2 20.3 %, DMM 3 9.4%, DMM 4 4.4%, DMM 5 2.3%, DMM 6 0.5%, DMM n (n>6) not detected.
Embodiment 3
[0034] Add in a 2L autoclave, sequentially add 800 g methylal and 400 g paraformaldehyde, 48 g Amberlite IRC-84 cation exchange resin, fill with nitrogen to a pressure of 3 MPa, heat to 90°C, and stir at 192 rpm Reacted for 8 hr, analyzed by gas chromatography after filtering off the catalyst, wherein DMM 44.4%, MeOH 5.8%, DMM 2 20.4 %, DMM 3 8.3%, DMM 4 3.2%, DMM 5 1.7%, DMM 6 0.4%, DMM n (n > 6) were not detected.
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Abstract
The invention relates to a method for preparation of polyoxymethylene dimethyl ether from paraformaldehyde, in particular to a method for preparation of polyoxymethylene dimethyl ether in the presence of an acidic resin catalyst and separation of polyoxymethylene dimethyl ether. The method adopts methylal and paraformaldehyde as raw materials to prepare polyoxymethylene dimethyl ether under mild reaction conditions. The reaction product is first subjected to molecular sieve adsorption, then to a reaction with an alkaline substance, and further to atmospheric and vacuum distillation so as to separate low-boiling point by-products and polyoxymethylene dimethyl ether (DMM3-8) as well as higher polymerization degree polyoxymethylene dimethyl ether (DMMn, with n being larger than 8), wherein the low-boiling point part and the high-boiling point part further react to prepare polyoxymethylene dimethyl ether. The separated polyoxymethylene dimethyl ether (DMM3-8) product can be directly used as a component for co-combustion with diesel.
Description
technical field [0001] The invention relates to the technical field of fine chemicals, in particular to a method for preparing polyoxymethylene dimethyl ether from paraformaldehyde, comprising a method for preparing polyoxymethylene dimethyl ether from methylal and paraformaldehyde in the presence of a modified acidic resin and The product is separated and suitable for diesel doping component DMM 3-8 Methods. Background technique [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 c...
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