自2009年以来，煤经合成气制乙二醇产业在我国迅速扩张，预计到2022年，我国煤制乙二醇总产能将增至1 368万t/a。日渐成熟的煤制乙二醇技术进一步带动了煤经合成气制可生物降解塑料聚乙醇酸的技术发展，即将煤制乙二醇技术中的草酸二甲酯选择性加氢为乙醇酸甲酯，再经聚合反应合成可降解塑料聚乙醇酸。聚乙醇酸既定位为聚酯行业的高端产品，也用于生产可完全降解聚酯制品，是国家鼓励发展的新型材料，在“限塑令”实施的国家和地区具有较大的市场需求潜力和需求空间，因此，开展煤经合成气制可降解聚乙醇酸这一分支技术的研发，对丰富煤制乙二醇产业的产品结构具有重要意义。围绕煤经合成气制可降解聚乙醇酸技术的研发进展，论述了草酸二甲酯选择性加氢制乙醇酸甲酯单体和乙醇酸甲酯聚合制聚乙醇酸的技术原理，以及该技术路线的工程设计方案和可行性。对于乙醇酸甲酯单体的合成，其技术关键在于通过设计和调整催化剂的结构、组分以及优化反应条件，实现草酸二甲酯的高转化率和乙醇酸甲酯的高选择性。对于乙醇酸甲酯制聚乙醇酸，目前主要有2种工艺技术，即以乙醇酸甲酯为原料或经乙醇酸的直接缩聚法和经乙交酯的开环聚合法。聚合工艺的选择直接影响聚乙醇酸的产品质量：直接缩聚法生成低分子量的聚乙醇酸，开环聚合法可以生成高分子量的聚乙醇酸。发展煤经合成气制可降解聚乙醇酸技术，将有利于我国煤制乙二醇产业的发展和拓展。

Since 2009, the coal-to-ethylene glycol technology via syngas has been rapidly expanded in China, and the total production capacity of ethylene glycol is estimated to reach 13.68 Mt/a by 2022. The increasing maturity of coal-to-ethylene glycol technology further drives the technical progress of biodegradable plastic polyglycolic acid from coal via syngas, that is, dimethyl oxalate in the coal-to-ethylene glycol technology is selectively hydrogenated to methyl glycolate, and then the methyl glycolate is polymerized to degradable plastic polyglycolic acid. Polyglycolic acid is not only positioned as a high-end product in the polyester industry, but also used to produce fully degradable polyester products. It is a new material that has great market demand potential and space, encouraged by countries and regions where the "plastic limit order" is implemented. Thus, the R & D of the branch technology of degradable polyglycolic acid from coal via syngas is of great significance to enrich the product structure of the coal-to-ethylene glycol industry. Focusing on the R & D progress of degradable polyglycolic acid from coal via syngas, this review discussed the technical principle of hydrogenation of dimethyl oxalate to methyl glycolate monomer and polymerization of methyl glycolate to polyglycolic acid, as well as the engineering design and feasibility of this technical route. For the synthesis of methyl glycolate monomer, the key technology to achieve high conversion of dimethyl oxalate and high selectivity of methyl glycolate lies in designing and adjusting the composition and structure of the catalyst and optimizing the reaction conditions. For the preparation of polyglycolic acid from methyl glycolate, there are two main techniques: direct polycondensation method with methyl glycolate or glycolic acid as raw material and ring-opening polymerization method with glycolide as raw material. The quality of polyglycolic acid products can be significantly affected by different polymerization processes: low molecular weight polyglycolic acid can be produced by direct polycondensation and high molecular weight polyglycolic acid can be produced by ring opening polymerization. The development of degradable polyglycolic acid technology from coal via syngas will be conducive to the development and expansion of China′s coal-to-ethylene glycol technology.

0 引言

1 PGA及其单体概述

2 煤经合成气制PGA的技术原理

   2.1 DMO加氢制MG

   2.2 PGA制备方法

3 煤经合成气制PGA的工程设计

   3.1 设计方案

   3.2 工程化可行性

4 结语与展望