生物乙醇催化转化为丁醇的立体位阻催化剂设计

As the flourishing of ethanol production, upgrading ethanol to butanol, which has similar energy density to gasoline, has been regarded as one of the vital method of ethanol utilization. Nevertheless, the butanol selectivity is yet to be improved owing to the uncontrollable aldol condensation and consequential reaction of butanol. Hence, it is highly attractive to design novel catalysts to depress the butanol conversion and improve the butanol selectivity. In this project, based on the structure of highly active homogenous catalysts, novel catalysts with sterically crowded micro reaction environment will be constructed by using the meso-pore of carbon and lamellar structure of hydrotalcite, which will depress the butanol conversion, and enhance the yield of butanol. Meanwhile, the active sites of catalysts and the intermediates during the reaction will be characterized and monitored by using microcalorimetric adsorption, in-situ FTIR-ATR and on line MS, which will be used to construct the relationship between active sites of catalysts and elementary reactions under reaction conditions. Combine with the kinetic study, active sites for different reaction steps will be coupled. The results of this project will guide the fundamental theory about conversion of ethanol to value-added chemicals, and provide useful information on space confined catalysts designing.

随着乙醇的规模化生产，将其高质化转化为与汽油相近能量密度的丁醇已经成为乙醇利用的重要途径。然而，乙醇催化转化到丁醇存在非均相催化剂上羟醛缩合难以控制、产物丁醇会进一步反应等难题，丁醇选择性较差，亟待设计新型催化剂体系，阻止产物的进一步转化，提高产物选择性。本项目拟借鉴均相催化剂的立体空间位阻结构，利用介孔碳的孔道和水滑石的片层间距，构筑具有立体位阻微反应环境的新型催化剂，抑制丁醇的进一步转化，提高丁醇选择性；在此基础上，采用微量吸附量热、高压液相红外和在线质谱等表征和测试手段，对催化剂活性中心和反应活性物种进行原位表征，建立反应条件下催化剂与单步反应的应答机制，并借鉴动力学参数，实现不同活性中心单步反应的有机耦合。本项目的实施将为乙醇选择性转化为高附加值化学品提供理论依据，同时为空间限制催化剂设计提供重要参考。

乙醇是产量最大的生物质平台分子，被广泛掺加到汽油（E10）中，部分替代不可再生的石油资源。然而，乙醇的能量密度较低，具有吸湿性、腐蚀性等问题，严重影响其掺加规模。催化剂转化乙醇到丁醇搭建了丰富乙醇和高能量密度丁醇的桥梁，对乙醇的高附加值应用具有重要的意义。此反应中，新型催化剂的开发是平衡乙醇转化率和丁醇选择性的关键。本项目基于均相催化剂结构，从微反应环境构建和多步反应耦合角度入手，设计合成孔道限制的新型催化剂体系，提高乙醇转化率和丁醇选择性。同时，对乙醇脱氢、羟醛缩合和氢转移等基元反应步骤进行研究，结合反应动力学确定关键速率控制步骤和活性位点。最后，结合原位红外等手段，准确描述催化剂特殊空间结构和乙醇转化反应之间的内在关系。本项研究加深了对乙醇转化反应机理的认识，明确了多步反应催化剂设计合成思路，成功将均相催化剂空间概念引入非均相反应体系中，为乙醇转化和生物质利用提供理论支持。