NSF/EPA: Nearcritical Water for Environmentally Benign Chemical Processing

Eckert近临界水（NCW）是一种环保型溶剂，为化学，石化，制药和塑料行业的各种制造过程提供了巨大的污染预防机会。在250-350C范围内，NCW具有与环境丙酮相似的密度和介电常数，允许有机和离子物质的溶解和反应，以及聚合物的膨胀。与用于完全氧化的超临界水（通常为400℃）不同，更温和的温度允许更大范围的有用反应。最后，在环境温度和压力下，NCW的电离常数比水大三个数量级。在没有添加酸和碱的情况下，后一种性质有助于促进酸和碱催化反应。本研究建议首先收集、批判性地评估、扩展和模拟NCW中有机物的热力学数据数据库（主要是溶解度）。接下来将获得各种工业上有意义的重要反应的动力学数据。这些信息将促进这项技术在工业界的商业化，特别是在这项提议的积极合作者杜邦公司。将运行的反应如下：o Friedel-Crafts烷基化反应o Friedel-Crafts酰化反应o烷基芳烃氧化o缩合聚合物水解解聚o异构化反应o纤维素水解我们已经有了初步的动力学数据，证明烷基化反应可以在不添加任何酸催化剂的情况下成功进行。酰化反应可以用少量的催化剂来代替通常使用的2-3倍摩尔过量的氯化铝。作为这些调查的结果，将可利用“绿色化学”促进可持续发展的新工艺。NCW将取代许多不太理想的溶剂，如芳烃和氯化化合物，它将避免使用污染矿物酸和有害催化剂，它将允许最小化甚至消除不需要的副产物，它将提供更好的反应控制，可以均匀运行而不是多相运行，它将通过废物再利用促进封闭过程。＊＊＊

9613063 Eckert Nearcritical water (NCW) is an environmentally-benign solvent that offers tremendous opportunities for pollution prevention for a wide variety of manufacturing processes in the chemical, petrochemical, pharmaceutical, and plastics industries. In the range 250-350C, NCW has a density and dielectric constant similar to that of ambient acetone, permitting the dissolution and reaction of both organic and ionic species, as well as the swelling of polymers. Unlike supercritical water, which is used for complete oxidation (usually 400C), the more moderate temperatures permit a wider range of useful reactions. Finally, NCW has an ionization constant which is three orders of magnitude greater than water at ambient temperatures and pressures. This latter property should facilitate promotion of acid- and base- catalyzed reactions in the absence of added mineral acids and bases. This investigation proposed first to gather, evaluate critically, expand, and model the database of thermodynamic data (primarily solubilities) for organics in NCW. Next kinetic data will be obtained for a variety of important reactions which are of industrial interest. Such information will facilitate the commercialization of this technology by industry, especially by the active collaborator on this proposal, DuPont. The reactions that will be run will be: o Friedel-Crafts alkylation reactions o Friedel-Crafts acylation reactions o Oxidation of alkyl aromatics o Hydrolytic depolymerization of condensation polymers o Isomerization reactions o Hydrolysis of cellulose We already have preliminary kinetic data that demonstrate that one alkylation reaction can be run successfully without any added acid catalyst, and that an acylation reaction can be run with only traces of a catalyst in place of the 2-3 fold molar excess of AlCl 3 usually used. As a result of these investigations, new processes will be available using "green chemistry" for sustainable development. NCW will replace ma ny less desirable solvents, such as aromatic hydrocarbons and chlorinated compounds, it will avoid the use of polluting mineral acids and hazardous catalysts, it will permit the minimization of even the elimination of unwanted byproducts, it will provide better control of reactions which can be run homogeneously instead of heterogeneously, and it will facilitate closed processes by reuse of waste material. ***