负载型金属纳米粒子与固体碱协同催化解聚和选择转化碱木质素的机制研究

With the global climate warm and the depletion of fossil resource, it is extremely urgent to study non-fossil chemicals and fuels. Lignin biomass is the natural feedstock for refining aryl chemicals and high-energy density fuels because of high-energy density and rich aromatic ring structure in lignin. However, the complex and compact polymerization structure extremely limit the high-value transformation and efficient utilization of lignin. In this work, straw alkali lignin from paper industry by-product is used as material to study the mechanism of the catalytic depolymerization and selective conversion of lignin. The multifunction catalyst with magnetism is designed and prepared by loading transition metal nanoparticles on solid alkali. The effects of the synergistic catalysis depolymerization and selective conversion of alkali lignin into C7-C12 aryl compounds by the supported metal coupled with solid alkali are evaluated. And a series of studies are implemented including the change rule and characteristic of lignin molecular structure during catalytic depolymerization process, depolymerization and conversion products and their formation mechanism, and main influence factors on catalytic depolymerization and conversion. Also, the interactional essence between lignin molecule and catalyst under the complicated environment and interfacial condition is calculated and simulated using the method of calculational chemistry. These works are to ascertain the pathway of catalytic activation and breakage of chemical bonds in lignin by the prepared catalyst, to clarify the structure-activity relationship between the structure, activity of catalyst and the depolymerization, conversion as well as product yield of lignin, and then to propose the molecule mechanism of the catalytic conversion of lignin into C7-C12 aryl compounds. These results may provide the scientifically theoretical and practical foundation for the design and optimization strategy for the high-value conversion of lignin.

随着全球变暖及化石资源的枯竭，研究非化石基化学品和燃料已迫在眉睫。木质素能量密度高且富含芳环结构，是炼制芳基化学品和高能量密度燃料的天然原料。然而，复杂且致密的聚合结构，极大地限制了木质素资源的高值转化和有效利用。本课题以造纸副产物秸秆碱木质素为研究对象，设计并制备具有磁性的固体碱负载过渡金属纳米粒子型多功能催化剂，评价负载金属与固体碱协同催化解聚和选择转化碱木质素为C7-C12芳基化合物的效果，并通过对解聚过程木质素分子结构变化规律及特征、解聚与转化产物及其形成机制、影响解聚转化主要因素等的研究，以及在微观层次上对复杂环境及界面条件下木质素与催化剂相互作用本质的计算与模拟，探明木质素结构中化学键催化活化与断裂历程，阐释催化剂结构、活性与木质素解聚、转化及产物收率的构效关系，提出木质素催化转化为C7-C12芳基化合物的分子机制，为木质素高值转化方案的设计与优化提供科学的理论和应用依据。

随着全球变暖及化石资源的枯竭，研究非化石基化学品和燃料已迫在眉睫。木质素能量密度高且富含芳环结构，是炼制芳基化学品和高能量密度燃料的天然原料。然而，复杂且致密的聚合结构，极大地限制了木质素的高值转化和有效利用。本项目以造纸副产物秸秆碱木质素为研究对象，设计并制备了系列多功能催化剂，研究了该催化剂催化转化木质素的构效关系、产物分布和选择性，并结合理论计算结果，阐释了催化转化木质素制精细化学品的机制。取得的主要成果有：.(1)耦合金属催化和固体碱催化作用，木质素经Ni/CaO-HZSM-5(60)和Ni/HZSM-5(60)串联催化，能大幅度提高乙苯产率和选择性，并阐释了反应机制。.(2)成功制备了CeO2促进的双功能催化剂Ni10CeO2/H-ZSM-5，催化木质素β-O-4键断裂生成乙苯的选择性高达63.4%，提出了催化转化的机理。.(3)原位制备了一种高效、磁性易分离Ni@C催化剂，该催化剂实现了愈创木酚及木质素油的高效催化转化，产物选择性可达84%。同时当在体系中加入H-ZSM-5进行串联催化时，对愈创木酚的转化率达到99%，产物选择性96%，其反应机理是高催化活性主要源于不同热解温度导致的Ni2+/Niδ+比以及碳缺陷的差异性。.(4)原位组装-蚀刻制备氮掺杂空心碳多面体笼锚定钴镍催化剂CoNi/NC，使木质素热解油在低氢条件下实现高选择性加氢脱氧，获得87.8%的总液体产物收率，其中单体产物收率53.4%。该研究为木质素加氢脱氧制环烷烃燃料提供了一种低能耗的新途径。.(5)催化剂W-Ni/MSM协同固体酸催化转化木质纤维素，低碳二元醇总产率达到82.4%，其中乙二醇产物选择性为67%，并提出了木质纤维素催化转化制低碳二元醇的反应历程。制备的Ni3W-MMO金属氧化物催化剂，在适宜的条件下，可实现木质纤维素100%转化，产物乙二醇收率42%。.上述研究结果不仅对生物质木质素高效转化方案的设计有重要的理论指导意义，而且可突破限制木质素高值化利用中的一些科学瓶颈问题，更好的促进木质素基燃料和化学品的有效开发。发表学术论文11篇，申请国家发明专利3件，其中授权2件；培养研究生5名（硕士生3名，博士生2名），获科研奖励1项，完成科技成果评价1项。