溶解浆预水解液转化为2-甲基呋喃的多元金属催化剂构建及其催化机理研究

Developing efficient biomass upgrading catalysts is very important for the sustainable conversion of biomass into energy and chemicals. However, the development of biomass upgrading catalysts mainly depends on the empirical method, which has many defects, such as long research period, poor universality, difficult to study the catalytic mechanism, etc. Generally, the manufacture of dissolving pulp produces a large amount of pre-hydrolysate, which mainly contains low concentrations of hemicelluloses and their degradation products with low calorific value. High energy consumption is always required for the recycle or reutilization of the pre-hydrolysate. Here, we intend to directly use the pre-hydrolysate as raw material, formic acid as early stage catalyst and in-situ hydrogen source, multi-metal as catalyst, to convert the pre-hydrolysate into slightly soluble, low boiling point, and high value-added 2-methylfuran. The multi-metal catalyst will be constructed by CASTEP module based on density functional theory. The active species–metal binding energies and activation energies of formic acid degradation for in-situ hydrogen, hydrogenation of furfural to furfural alcohol and hydrogenolysis of furfural alcohol to 2-methylfuran will be calculated by computational chemistry methods. The catalytic activities of single metals will be measured by experimental methods. Then the relationships among the active species-metal binding energies, reaction activation energies and catalytic activities will be established to facilitate the construction of the multi-metal catalysts. The catalytic mechanism of the multi-metal catalysts will be revealed from the molecular level. This research is essential for exploring efficient catalyst for biomass upgrading, as well as sustainable utilization of lignocellulosic biomass.

生物质高效转化催化剂的开发对生物质可持续地转化为能源及化学品至关重要。然而，目前生物质转化催化剂的研究主要依靠经验性方法，存在研究周期长、普适性差、难以深入研究催化机理等弊端。本项目针对溶解浆预水解液中半纤维素及其降解产物浓度和热值低、回收能耗高等问题，拟直接以溶解浆预水解液为原料，以甲酸作为前期催化剂和原位氢源，采用基于密度泛函理论的CASTEP模块构建糠醛转化为2-甲基呋喃所需的多元金属催化剂，通过计算甲酸降解供氢、糠醛加氢生成糠醇以及糠醇氢解生成2-甲基呋喃反应过程中活性分子与不同金属表面的结合能和反应活化能，测定不同金属催化剂的催化活性，明确表面结合能、反应活化能和催化活性三者的相互关系，从分子水平上阐释多元金属催化作用的反应机理，实现预水解液高效转化为微溶、低沸、高附加值的2-甲基呋喃。本研究无论对于生物质高效转化催化剂的开发还是木质纤维素资源的可持续利用都具有重要意义。

生物质高效转化催化剂的开发对生物质的转化利用十分重要。本项目针对溶解浆生产过程中产生的预水解液转化利用方面的难题，探索了甲酸的加入对木材原料预水解过程中原料和预水解液组成的影响，结果显示甲酸的加入能明显加速半纤维素的脱除，但是在高温下会造成纤维素的过度降解，容易造成成浆质量降低；提出了一种采用稀土金属改性分子筛并协同甲酸催化木糖和半纤维素水相中转化制备糠醛的方法，可以较为显著的提高水相体系反应中糠醛的产率；探索了固体酸负载铜系催化剂以及氧化亚铜催化糠醛原位加氢产物，结果显示固体酸负载的铜系催化剂会导致产物中出现大量的醚化副产物，而氧化亚铜则在糠醛加氢制备糠醇方面具有良好的催化性能；除此之外，项目还结合企业需求，对预水解液中主要组分的利用进行了探索，提出了水热酸解快速分离预水解液中木质素和半纤维素的方法，采用酸法和酶法直接将预水解液中半纤维素转化为低聚木糖，开发了预水解液直接水热碳化制备炭微球技术并将其用于污染物吸附，探索了工业木质素一步法制备离子交换树脂以及工业木质素制备香草醛的可行性，为预水解液的资源化利用提供了新的思路。