乙醇制丁醇新型界面催化体系的构建及其反应机制研究

Butanol is one kind of important raw materials for different chemicals and one kind of highly efficient biofuels for vehicles. Catalytic transformation of ethanol is expected to provide a new route for sustainable production of n-butanol. However, it is very difficult to control every reaction process of this transformation in the reported catalysis systems, which leads to some serious problems including harsh reaction conditions, low catalysis activity and low product selectivity. To this end, this application will prepare novel Janus mesoporous carbon materials and then construct Pickering emulsion interfacial catalysis systems, which can spatially separate every reaction process of the transformation. When it is believed to improve the activity of ethanol dehydrogenation by tuning the interaction of electron transfer between the element N in the framework of materials and the noble metal nanoparticles, the large oil-water interface could fast transfer the intermediate product crotonaldehyde from the active site for offering a significant enhanced selectivity, so as to achieve converting ethanol to n-butanol with high activities and selectivities under mild reaction conditions. Furthermore, this application will elaborate the underlying correlations among catalyst structures, emulsion properties, reaction conditions and catalytsis performances. Also this application will attempt to reveal the multiple effect of inorganic base and the intrinsic mechanism of oil-water interface tuning the reaction selectivity. This design aims to construct a novel and highly efficient heterogeneous catalysis system for converting ethanol to n-butanol, and then establish groundwork for realizing sustainable and scale production of n-butanol.

丁醇是一种重要的化工原料和生物燃料，催化转化乙醇制丁醇有望为丁醇的可持续化生产提供新路线。然而，目前的催化体系难以控制反应的每一个过程，存在反应条件苛刻，催化活性和产物选择性较低等问题。为此，申请拟制备新型Janus介孔碳材料，构建Pickering乳液界面催化体系，将每一个反应过程隔绝开来，调控材料骨架中N元素与贵金属纳米粒子之间的电子转移等相互作用，提高乙醇脱氢活性，利用巨大的油水界面迅速转移巴豆醛等中间产物，有效提高丁醇选择性，从而实现在温和条件下高活性高选择性转化乙醇制丁醇。在此基础上，阐述催化剂结构、乳液性质、反应条件等与催化性能之间相互关联的科学问题，并重点研究碱的多元化作用和油水界面调控反应选择性的内在机理。从而构建一个乙醇制丁醇的全新高效多相催化体系，为实现丁醇的可持续规模化生产奠定基础。

本项目针对乙醇制丁醇反应中存在的系列问题，以Janus型催化材料的设计制备和高效Pickering乳液界面催化剂体系的构建为主线开展研究。取得的重要进展主要包括：（1）设计制备出三种不同结构的Janus纳米颗粒，包括具有不同内表面和外表面的CNx@mSiO2双层空心球，具有不同表面性质的Janus介孔氧化硅纳米片，以及雪人状Pd&PMO介孔材料，建立了Janus催化材料的结构调控方法，构建了Janus材料的结构与性能之间的构效关系，并拓展了Janus催化材料在水相反应中的应用；（2）以Janus介孔氧化硅纳米片和超薄氮化碳纳米片为固体乳化剂，成功构建出一系列的高效Pickering乳液界面催化体系，利用纳米片独特的各向异性和良好的界面活性，从本质上加速了亲/疏水性分子在油-水界面的扩散速率，大幅提升了双相反应的反应效率；（3）深入探索了乙醇制丁醇Pickering乳液界面催化体系，初步探索了金属-酶Pickering界面串联催化体系用于丁醇制备，这种金属-酶串联催化体系有望用于在温和反应条件下高效转化烯烃制备一级醇；（4）发现油-水界面可以用于调控分子在金属颗粒表面的吸附构型，从而实现对反应选择性的有效调控，阐明了乳液界面水层的微环境（主要是氢键相互作用）是调控反应选择性的内在因素。这些研究工作，用Janus固体颗粒发展了全新的Pickering界面催化体系，从根本上解决了双相催化反应中的传质问题，提出了调控反应选择性的新策略，并从分子层面揭示了界面催化效应的科学本质。通过该项目的实施，申请人以第一作者或通讯作者共发表SCI论文6篇，具体包括Chem. Eng. J. 1篇，ACS Appl. Mater. Interfaces 1篇，Chem. Commun. 2篇，物理化学学报1篇，J. Mater. Chem. A 1篇。