A kind of formaldehyde separation, refined pode 2 method and device

Abstract

The invention proposes a method for separating formaldehyde and refining PODE 2 The method and device, including two rectification columns and a dehydration unit, wherein methanol, formaldehyde, PODE 2 The mixture with water enters the first rectification column, and at the same time, water is introduced at the appropriate position of the first rectification column, and formaldehyde-free mixture methanol, water and PODE are extracted from the top of the column. 2 , the tower still produces an aqueous solution containing formaldehyde, and the top extract of the first rectifying tower enters the second rectifying tower after the water is removed by the dehydration unit, and pure methanol is produced at the top of the second rectifying tower. Mining pure PODE 2 , the method and device of this patent effectively solve the problem that pure PODE cannot be obtained by rectification due to formaldehyde in the separation polymethoxydimethyl ether system. 2 The problem of formaldehyde polymerization and blockage of condensers and pipelines.

Description

technical field [0001] The invention belongs to the technical field of chemical engineering, and relates to a separation technology for synthesizing polymethoxydimethyl ether by using methanol and aqueous formaldehyde solution as reaction raw materials, and for separating formaldehyde and refining PODE. 2 method and device. Background technique [0002] Polymethoxy dimethyl ether is a new type of diesel fuel additive, the chemical formula is CH 3 O(CH 2 O)nCH 3 (where n is greater than 1, generally less than 10), with high oxygen content (42% to 51%) and cetane number (up to 76 on average), among which, PODE 3-5 It is the most ideal diesel additive, adding PODE to diesel 3-5 It can effectively reduce soot and particulate matter (PM) emissions from diesel engines and improve fuel economy. PODEn is a homologous component formed by acid-catalyzed polycondensation of raw materials providing etherate end groups and raw materials providing methoxy groups. Compounds that prov...

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Problems solved by technology

[0003] Over the years, domestic and foreign research teams led by BASF have done a lot of research on the synthesis and separation of PODEn, mainly reporting the route of methylal and paraformaldehyde from BASF (US 20070260094), Tsinghua University and Jade The methylal and paraformaldehyde route (CN104974025A) of Huang Chemical Co., Ltd., but because its reaction raw materials are anhydrous paraformaldehyde and paraformaldehyde, the composition of the reaction product is simple, and its separation process cannot be applied to the separation of synthetic products through other reaction routes; In addition, there is the reaction and separation process of methanol and formaldehyde aqueous solution (US 2008207954, US20080221368, US 7671240, US 7700809) of BASF Company. Limits the industrialization of its process

[0004] The route of synthesizing polyoxymethylene dimethyl ether with methanol and formaldehyde aqueous solution as the reaction system has the advantage of low raw material cost, but the difficulty of product separation limits the industrial application of this route

The azeotrope of methyl formate, methylal and methanol in the product of synthesizing polyoxymethylene dimethyl ether, PODE 3-10 It can be separated by simple distillation, but due to methanol, water, PODE 2 and formaldehyde system will form PODE 2 -Formaldehyde-Water, PODE 2 -Multiple complex azeotropes such as formaldehyde-methanol, so it is difficult to convert formaldehyde from PODEn product PODE 2 Separation out, refined to obtain pure PODE 2 , and formaldehyde is easily polymerized into solids during the rectification process to block the condenser and pipelines, affecting the continuity of production

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