Yolk/shell 固体催化剂催化乙酰丙酸和甲酸制备γ-戊内酯的研究

To solve the problems of environmental pollution and energy shortage, it is significant to produce γ-valerolactone from biomass. γ-Valerolactone is regarded as a potential high value-added chemical and biofuel from biomass. Levulinic acid and formic acid can be produced from the cellulose component in biomass. Formic acid can be used as the resource of H2 in the presence of catalyst to produce higher valuable chemical γ-valerolactone from levulinic acid via a reduction process. However, liquid products from biomass conversion are usually complex, resulting in the difficult separation of levulinic acid and formic acid from reaction aqueous solution. In addition, some reported catalysts exhibited low stability in water reaction system. Therefore, highly active and stable catalyst is required for the preparation of γ-valerolactone directly from biomass. In this project, we intend to develop some new biofunctional catalysts M@ZrO2, with high catalytic activity and stability to catalyze the preparation of γ-valerolactone directly from biomass. We can sduty the structures of catalysts by changing the diameter of shell. Based on the characterization of catalysts, the relationship between catalytic activities and structural features are studied. The effect of products from cellulose conversion such as oligomers, glucose, acetic acid, and lactic acid on the activity of prepared catalysts are also investigated. Furthermore, the prepared catalysts are used to catalyze the preparation of γ-valerolactone directly from the reaction aqueous solution of corncob residue conversion.

γ-戊内酯是一种具有潜在应用价值的高附加值化学品。以源于生物质的乙酰丙酸和甲酸制备γ-戊内酯,对用可再生资源替代传统化石资源制备化工产品具有非常重要的意义。但由生物质制备的乙酰丙酸和甲酸混合液副产物多且酸性较强，造成分离困难和催化剂活性组分流失。由此,直接由生物质制备γ-戊内酯，要求发展适应复杂体系的高活性、高稳定性的催化剂。本项目拟发展新型Yolk/shell双功能固体催化剂M@ZrO2，催化甲酸分解产生氢气原位还原乙酰丙酸并进一步脱水生成γ-戊内酯。优化制备条件，调变催化剂核的组成与结构、壳的孔径及分布，探索催化剂的构效关系；获得对乙酰丙酸和甲酸制备γ-戊内酯具有高催化活性和稳定性的催化剂。模拟直接以木糖渣制备乙酰丙酸的液体产物为原料的复杂反应体系,探索几种主要副产物对生成γ-戊内酯的影响；为发展新型催化剂催化直接由生物质制备高附加值化学品提供一定的理论依据和实验基础。

以源于生物质的乙酰丙酸和甲酸为原料制备γ-戊内酯，对用可再生资源替代传统化石资源制备化工产品具有非常重要的意义。针对于由生物质获得的乙酰丙酸和甲酸混合液副产物多且酸性较强，造成分离困难和催化剂活性组分易流失的难题，本项目同时制备了不同组成和结构的Yolk/shell M@ZrO2和负载型M/ZrO2 固体催化剂，其中M包括Au、Pt、Ru等；并研究了其催化甲酸分解产生氢气原位还原乙酰丙酸并进一步脱水制备γ-戊内酯的催化活性。通过调变催化剂活性中心的组成与结构、壳的孔径及分布等，揭示了不同的制备条件对催化剂的结构的影响。Yolk/shell Au@ZrO2和负载型Au /ZrO2催化剂相较于其他金属催化剂对催化乙酰丙酸-甲酸制备GVL表现出了更好的催化活性。优化了催化反应条件，阐明了不同反应温度、时间、催化剂用量等对GVL收率和选择性的影响。以纯乙酰丙酸-甲酸为原料时，获得了高达87.9%收率和98.7%选择性的GVL。通过对催化剂结构进行表征，揭示了催化剂的结构与其活性之间的关系。进一步以原生生物质糠醛渣等为原料，采用分步法，获得了高收率和高选择性的GVL。首先，发展了SnCl4催化体系，获得了高收率、高选择性的乙酰丙酸-甲酸混合物；进一步以此混合液为原料，GVL的最高收率为50.5%（基于原生生物质中纤维素的质量）。Au@ZrO2比Au/ZrO2催化剂具有更好的重复利用率。探明了由木糖渣转化制备乙酰丙酸和甲酸时生成的主要副产物对催化剂催化性能以及对由乙酰丙酸和甲酸生成γ-戊内酯的影响机制。为发展新型催化剂催化直接由生物质制备高附加值化学品提供了一定的理论依据和实验基础。.该项目在执行期间严格按照原项目计划执行，完成了原计划研究内容，实现了原计划研究目标。总体上获得了对乙酰丙酸和甲酸制备γ-戊内酯具有高活性、选择性和高稳定性的固体催化剂，并探明了催化剂的结构与性能之间的关系。获得了较好的研究成果：发表了高水平SCI论文3篇、会议论文3篇 ，培养本科生3名、硕士生4名、博士生1名；并作为第二完成人参与完成专著一部。