Catalytic Dehydration of Carbohydrates in Near- and Supercritical Polar Solvents

生物工艺可以利用可再生生物资源以中等成本生产大量的乙醇、i-丙醇、乳酸和1-丁醇。这些生物制品在超临界水中的酸催化脱水可以在超过22 MPa的压力下获得重要的高价值石化产品乙烯、丙烯、丙烯酸和1-丁烯的高产率。因此，这些工业上重要的单体可以在适合于直接合成聚合塑料（如聚乙烯和聚丙烯）的压力下，从生物基质的稀水相溶液中生产出来。同样，戊糖和己糖也可以高产得糠醛和5-羟甲基糠醛。这些呋喃醛在工业上用于合成树脂。不幸的是，寄生反应竞争消耗生物底物并降低高价值单体的产量。本研究的目的是确定这些竞争反应的机理和动力学，以确定优化双键形成脱水反应收率的条件和催化剂。这项工作的关键要素是它强调了超临界水作为反应介质。夏威夷和许多发展中热带国家（如泰国和菲律宾）如果能确定蔗糖发酵产物的更高价值用途，它们的农业经济可能会复苏。同样，内布拉斯加州、堪萨斯州、爱荷华州和其他中西部各州将受益于乙醇、乳酸和其他玉米制品工业发酵产品的替代、更高价值的使用。从生物材料中生产塑料、树脂和石化中间体可能是改善以糖和玉米为基础的农业经济的最有希望的选择。先前的工作已经揭示了超临界水催化作为一种从生物材料生产石化产品的新方法的前景。这项研究将为工业开发这种新的反应化学奠定基础。

Biological processes can produce large quantities of ethanol, i-propanol, lactic acid, and 1-Butanol at moderate cost from renewable biological resources. The acid catalyzed dehydration of these bioproducts in supercritical water can result in high yields of the important high value petrochemicals ethylene, propylene, acrylicacid, and 1-Butene at pressures exceeding 22 MPa. Thus these industrially important monomers can be produced from dilute aqueous phase solutions of the biological substrate at pressures appropriate for the direct synthesis of polymeric plastics, such as polyethylene and polypropylene. Similarly, furfural and 5-hydroxymethyl furfural can be obtained from pentoses and hexoses in high yields. These furaldehydes are used industrially to synthesize resins. Unfortunately, parasitic reactions compete to consume the bio-substrate and reduce the yield of the high-value monomer. The objectives of this research are to identify the mechanisms and kinetics of these competing reactions in order to determine conditions and catalysts which optimize yields of the double bond forming dehydration reactions. The key element of this work is its emphasis of near and supercritical water as a reaction medium. Hawaii and many of the developing tropical countries (such as Thailand and the Philippines) could enjoy a resurgence of their agricultural economies if higher value uses for the fermentation products of sucrose were identified. Similarly, Nebraska, Kansas, Iowa, and other mid-western states would benefit from alternative, higher value uses for ethanol, lactic acid, and other fermentation products of the corn products industry. The production of plastics, resins, and petrochemical intermediates from bio-materials is perhaps the most promising option for improving the economics of sugar- and corn-based agricultural economies. Prior work has revealed the promise of catalysis in supercritical water as a new method for producing petrochemicals from bio-materials. This research will lay the foundation for industry to exploit this new reaction chemistry.