铜催化醋酸仲丁酯转移加氢制备甲乙酮及其反应机理研究

Catalytic conversion of C4 hydrocarbons to the value-added methyl ethyl ketone (MEK) via sec-butyl acetate (SBA) and 2-butanol provides an effective way to utilize C4 fractions from refineries and petrochemical plants. Coupling of the SBA hydrogenation and the 2-butanol dehydrogenation over a single Cu-based catalyst can recycle efficiently the reaction heat and hydrogen released respectively in the hydro- and dehydrogenation processes, resulting in the reducing energy and hydrogen consumption in the production of MEK. .. Metallic Cu particles with the controllable size on diverse metal oxides are prepared using an ammonia evaporation method and examined, in terms of catalyst structure and acid-base properties, in the hydrogenation of SBA to 2-butanol, dehydrogenation of 2-butanol to MEK and the coupling of the above hydro- and dehydrogenation processes via hydrogen transfer. After that, copper catalysts with the desired structure and surface properties will be constructed and employed to investigate the site requirement, as well as the structure-function relationship of catalysts, for the catalytic transfer hydrogenation of SBA to MEK. .. Considering the adsorption and activation behaviors of SBA, 2-butanol and MEK on the catalyst surface, project applicants will reveal the detailed mechanism for the coupling of dehydrogenation of 2-butanol and hydrogenation of SBA over Cu-based catalysts, and develop an effective strategy to regulate the reaction path for the catalytic transfer hydrogenation of SBA to MEK. The project has been intended to not only explore an environmentally benign route to produce MEK from SBA under mild conditions, but disclose the reaction mechanism and kinetics for the catalytic transfer hydrogenation of SBA, providing general knowledge of developing coupling processes for hydrogenation of other esters.

碳四混烃经由醋酸仲丁酯和仲丁醇制备甲乙酮是实现碳四资源增值利用的有效途径，在单一催化剂上耦合仲丁醇脱氢和醋酸仲丁酯加氢能够实现反应热和氢气的原位补偿并大幅降低甲乙酮产品的氢耗和能耗。本项目拟采用“蒸氨法”在不同金属氧化物表面制备具有特定尺寸的金属铜粒子，研究催化剂结构和酸碱特性对醋酸仲丁酯加氢制备仲丁醇，仲丁醇脱氢制备甲乙酮以及二者氢转移耦合反应性能的影响。在此认识基础上构筑具有特定结构和表面性质的铜基催化剂，并重点研究醋酸仲丁酯催化转移加氢制备甲乙酮的活性位点需求和催化剂的构效关系；同时结合醋酸仲丁酯、仲丁醇和甲乙酮在催化剂表面的吸附、活化规律，进而揭示醋酸仲丁酯催化转移加氢的反应机制并建立调控反应路径的有效策略。相关研究不仅有望实现温和条件下醋酸仲丁酯催化转移加氢制备甲乙酮，而且可望明确醋酸仲丁酯催化转移加氢的反应机制和动力学，为其它酯类化合物的耦合加氢提供理论和方法参考。

碳四混烃经由醋酸仲丁酯和仲丁醇制备甲乙酮是实现碳四资源增值利用的有效途径。其中，仲丁醇脱氢和醋酸仲丁酯加氢反应之间的耦合能够实现反应热和氢气的原位补偿并大幅降低甲乙酮产品的氢耗和能耗。为此，项目组设计并制备了不同结构的铜基催化剂并详细研究了其催化醋酸仲丁酯加氢、仲丁醇脱氢以及仲丁醇脱氢和醋酸仲丁酯加氢耦合反应的性能。结果表明：（1）Cu/ZrO2催化剂具有较高的醋酸仲丁酯加氢活性，但在反应中因Cu物种的流失而易于失活；引入助剂B2O3能够减缓Cu物种的流失却降低了催化剂的活性和选择性；（2）工业Cu/Al2O3催化剂催化醋酸仲丁酯加氢反应的选择性差，采用CaO和B2O3修饰后能够显著提高其催化醋酸仲丁酯加氢反应的选择性和结构稳定性。Cu/B/Ca/Al2O3催化剂在反应1000 h后因表面部分CaO物种转变为醋酸钙以及含碳有机物的沉积而部分失活，但失活后的催化剂的结构和活性可以通过简单焙烧的方式进行再生；（3）Cu/B/Al2O3能够高选择性地催化仲丁醇脱氢制备甲乙酮，但催化剂的活性因Cu粒子的聚集随反应时间的延长而持续降低；（4）和醋酸仲丁酯加氢相比，仲丁醇脱氢和醋酸仲丁酯加氢反应的耦合能够将反应的氢压从8 MPa大幅度降低到0.6 MPa并且甲乙酮产物的选择性高达99%，表明实际工程应用中通过醋酸仲丁酯加氢产物回流的方式有望实现于温和条件下醋酸仲丁酯催化转移加氢直接制备甲乙酮。. 此外，为拓展甲乙酮产品的价值链，项目组进一步制备了Pd-Na/Zr-Mn-Zn-O催化剂并在温和的反应条件下实现了甲乙酮和甲醇缩合制备甲基异丙基酮和二乙基酮等高价值精细化学品。初步实验结果显示该反应经由甲醇脱氢生成甲醛、甲乙酮和甲醛醇醛缩合、羟醛脱水和不饱和酮选择性加氢等过程并且遵从位点分离的反应机制，这将为后续催化剂的理性设计和反应过程优化提供参考。