乙酸甲酯加氢制乙醇铜基催化剂的纳米构筑及其催化加氢性能的研究

Ethanol, as an important chemical for energy application and a promising fuel alternative or additive, has shown huge commercial potential in the market. The route of ethanol synthesis from syngas via carbonylation of dimethyl ether (DME) followed by hydrogenation of methyl acetate (MA) is applicable for the structure of fossil energy reserves of China, and could promote a clean and diversified development of energy. Due to its excellent activity and selectivity for C-O/C=O bonds hydrogenation, Cu-based catalyst has been widely used in gas-phase ester hydrogenations. The relevant studies would contribute to the development of this process as well as the rational design and the analysis of structure-function relationship of other catalysts for hydrogenations..This proposal focuses on the fabrication of nano-structured Cu-based catalysts with highly dispersed Cu(0) and massive Cu(I) species simultaneously and the analysis of their structure-function relationship. The main contect includes the following aspects. 1) Elucidating the effect of N-functionalized surface on the coordination enviroment and valence states of active copper species, as well as the consequent influence on catalytic performance by a combination of experiment and DFT calculation; and fabricating Cu-based catalysts with highly dispersed Cu(0) and massive Cu(I) species simultaneously by using N-functionalized support with space restriction effect. 2) Based on the above studies, adjusting the diameter of hollow spheres to investigate the morphology effect of catalyst on the adsorption and diffusion properties of the reactants. Revealing the enrichment effect of unique morphology and applying it in further design of catalyst to reduce the H2/ester molar ratio in feed. 3) Fabricating the core-shell nanoreactor with bi-function of DME carbonylation and MA hydrogenation, which may realize the one-step synthesis of ethanol from DME. It is anticipated that these works would provide experimental and theoretical references for the design of hydrogenation catalysts and intergration stratergy of this route for ethanol synthesis from syngas.

乙醇是一种重要的能源化工品，可直接作为燃料或与汽油混合使用，市场潜力巨大。合成气经二甲醚羰基化制乙酸甲酯、乙酸甲酯加氢制乙醇新工艺符合我国能源结构特点，对促进我国能源多元化、清洁化发展具有重要意义。铜基催化剂因其优秀的选择性C-O/C=O键加氢能力，被广泛应用于气相酯类加氢中，其相关研究不仅有利于该工艺的进步，也可为其他加氢过程催化剂的设计与构效关系解析提供参考。.拟通过催化剂表面氮元素改性对活性铜物种进行锚定，并利用孔道限域效应，构筑同时具有高度分散Cu(0)与大量Cu(I)的铜硅催化剂，采用理论计算与实验相结合的手段，考察氮改性对铜物种分布及催化性能的影响。合成空心球催化剂，揭示曲面形貌对反应物的富集作用，进一步将其应用于催化剂构建中，有效降低反应氢酯比。并通过构建羰基化和加氢双功能核壳型纳米反应器，实现二甲醚到乙醇的一步合成。为该工艺中加氢催化剂设计及工艺集成提供实验基础和理论指导。

低碳醇类（如乙醇、乙二醇）可用于油品添加剂、聚酯合成工业等，应用前景广阔。基于我国资源禀赋，开发合成气经乙酸甲酯加氢制乙醇、合成气经草酸二甲酯加氢制乙二醇等绿色工艺，是保障我国能源安全的重要基石。酯类加氢反应作为其中关键环节，其高效稳定的铜基催化剂的开发是研究的热点与难点。.本项目明确了硅源表面羟基数量对工业用的蒸氨法铜硅催化剂形成与演变规律，有效调控了其表面铜物种价态与数量分布。并针对其C3-4OH副产物多、长时间使用易结焦的问题，采用后接枝的方法，利用硅烷偶联剂对羟基的选择性覆盖，有效促进了易结焦物种的脱附，提升了催化剂稳定性，并减少了C3-4OH的生成。改变不同端位结构的硅烷偶联剂，解析了不同N物种的供电子作用及其对铜物种分布和催化性能的影响规律。.通过载体调变和助剂掺杂，探讨了催化剂表面不同的局部电子环境对活性铜物种分布及其酯加氢性能的影响。研究表明，表面氧空穴可与铜物种形成强相互作用，生成和稳定有利于酯类分子的吸附和活化的Cu&+物种，提升催化剂酯加氢性能。并发现相对于Cu&+物种，氧空穴及铜铈固溶体对酯类吸附性能较低，非关键活性相，揭示了催化剂酯加氢的活性界面，为催化剂活性物种构建提供了理论基础。.前期研究中，我们构建了表面组装有纳米管的空心球铜基催化剂，并发现其内凹曲面对氢气具有富集效应，可显著降低氢酯比。为进一步探讨具体结构参数对该现象的影响，我们通过改进制备方法，实现了对纳米空腔直径和纳米管长度的单因素可控合成。通过原位实验与理论计算，揭示了催化剂的空腔结构尺寸对氢气和酯类分子的吸附-扩散过程具有的平衡效应，明确了酯类分子尺寸等因素对最优空腔直径的影响规律。并发现纳米管限域孔道对产品选择性的反应-扩散耦合效应。基于该理论，设计了具有丰富褶皱结构的纳米花铜基催化剂，应用于碳酸乙烯酯加氢可显著降低氢酯比，并保持良好的活性、选择性和稳定性。