NSF/EPA: Biocatalytic Polymer Synthesis in and from Carbon Dioxide for Pollution Prevention

小行星9613166 这项研究有两个方向：一个是使用二氧化碳（CO2）作为反应物、溶剂或两者，另一个是使用酶作为CO2中的多相催化剂，在低温下选择性地促进所需的反应。CO2将在二醇和二酯的酶促聚合过程中用作溶剂，以形成聚酯多元醇（羟基封端的聚酯）。 聚酯多元醇是聚氨酯弹性体的重要组分。 目前，它们是通过二醇与二酸的高温反应产生的。 水的不断去除用于驱动反应完成。 通过与低温操作相关的节能以及通过使用酶脂肪酶消除循环副产物来实现污染预防。 所述酶可以使得能够产生二羟基封端的材料，而不诉诸高化学计量不平衡，从而减少浪费。 此外，酶与压力可调溶剂如CO2的协同使用使得能够生产具有窄分子量分布的聚酯。 这种材料目前使用常规缩合聚酯合成技术是不可得的。本研究亦将探讨聚合过程之细节，以合理设计一种连续式合成聚氨酯工业用多元醇聚酯中间体之方法。 二氧化碳将被用作原料，与酶催化相结合，用于合成氨基甲酸二苯酯，双酚A聚碳酸酯（BAPC）的单体，广泛使用的热塑性塑料。目前生产碳酸二苯酯的方法需要光气作为原料，产生大量的废盐和有机溶剂。 一个两步反应，其中CO2用于第一步生成碳酸二烷基酯，然后是酶催化的酯交换反应，将用于生产二苯基碳酸酯。 如果成功的话，这项研究将使用节省能源的反应物和工艺，最大限度地减少浪费，并使用环境友好的溶剂。

9613166 Russell The proposed research has two thrusts; one involves using carbon dioxide (CO2) as either a reactant, solvent or both, and the other uses enzymes as heterogeneous catalysts in CO2 to promote required reactions selectively at low temperatures. CO2 will be used as the solvent during the enzymatic polymerization of diols and diesters to form polyester polyols (hydroxy-capped polyesters). Polyester polyols are important constituents of polyurethane elastomers. Presently, they are generated via the high temperature reaction of diols with diacids. Constant removal of water is used to drive the reaction to completion. Pollution prevention will be accomplished through energy savings related to low temperature operation, as well as elimination of cyclic byproducts through use of the enzyme, lipase. The enzyme may enable the generation of dihydroxy capped material without resorting to high stoichiometric imbalances, thus reducing waste. In addition, the use of enzymes in concert with a pressure- tunable solvent such as CO2 enables the production of polyesters with narrow molecular weight distributions. Such materials are presently unavailable using conventional condensation polyester synthetic techniques. The proposed research also will investigate the details of the polymerization process in an attempt to rationally design a continuous method for synthesis of polyol polyester intermediates for the urethane industry. CO2 will be used as a raw material, in concert with enzymatic catalysis, in the synthesis of diphenyl carbamate, the monomer for bisphenol A polycarbonate (BAPC), a widely used thermoplastic. Current processes for production of diphenyl carbonate require phosgene as a raw material, generating large quantities of waste salt and organic solvent. A two-step reaction, where CO2 is used in the first step to generate a dialkyl carbonate, followed by an enzymatically catalyzed transesterification, will be used to produce diphenyl c arbonate. If successful, the research will use reactants and processes that save energy, minimize waste and use an environmentally benign solvent.