Ni/固体碱协同乳液催化生物质小分子醇水热C-C偶联合成高级醇燃料的研究

Bio-alcohol fuel is one of the most important clean alternative fuels, the production technology of small molecular bio-alcohols is mature, but the small molecule bio-alcohols have the disadvantages of high hygroscopicity, low energy density and corrosivity, so it’s not considered as the high-quality fuel component. As a result, the production of high-quality branched higher-alcohol fuels with high calorific value and hydrophobic properties from the C-C coupling of small molecule bio-alcohols is believed to be an important strategy to realize the high value utilization of biomass. Based on this, this project aims at the problems of high catalytic cost and carbon chain growth in traditional catalytic condensation process of small molecule alcohols, and combined with the formation of higher alcohol-water multi-phase system during the condensation process of small molecule alcohols, we proposed the strategy of emulsion catalysis to enhance mass transfer. To achieve that, the “non-noble metal-hydrophilic 2D solid alkali-lipophilic carbon” based NiSn/LDHs-C multifunctional amphipathic emulsion catalyst will be prepared, so that the multi-phase catalysis among emulsion droplet can be conducted in the higher alcohol-water multi-phase system to reduce mass transfer resistance and promote the contact between substrate and catalytic center, and solve the problem that it’s difficult for the substrate to react again and realize the carbon chain growth after phase separation. The project will carry out the investigation of the “reaction-mass transfer” cooperative enhancement mechanism in the hydrothermal catalytic conversion of small molecule bio-alcohols, the effect of bimetallic-base site and emulsifying ability of multifunctional catalyst on the catalytic process will be clarified. Furthermore, the catalytic reaction path also will be explored, the conversion efficiency and the physicochemical properties of the obtained C5+ higher-alcohol fuels will be evaluated. The project aims at realizing the low-cost production of high-valued higher-alcohol fuels via the novel one-step hydrothermal C-C coupling process of small molecule bio-alcohols, and this study provides a basic reference for the application and development of clean alternative fuels.

生物醇基燃料是重要的清洁替代燃料，其中生物质小分子醇生产工艺成熟，但存在高吸湿性、低能量密度等不足，以小分子醇缩合制疏水性、高热值的高级醇是生物质燃料化利用的重要策略。本项目针对小分子醇直接水相缩合中催化成本高和碳链增长难的问题，结合反应过程形成高级醇-水两相体系的特点，提出乳液化加强传质催化的策略；构建“非贵金属-亲水二维固体碱-亲油碳”耦合的NiSn/LDHs-C多功能两亲乳液催化剂，在高级醇-水两相体系中实现乳滴相际界面催化，减小传质阻力、促进底物与催化中心接触，解决相分离后底物难以反应增长碳链的问题。开展水热过程“反应-传质”协同强化机制研究，探究催化剂非贵金属-碱活性中心和乳化能力对反应的影响规律，揭示反应路径，评价过程转化效率及C5+高级醇产物的理化特性；实现小分子醇低成本一步法水热C-C偶联制高附加值C5+异构高级醇燃料的新途径，为清洁替代燃料的发展应用提供理论支撑。

生物醇基燃料是重要的清洁替代燃料，本项目重点研究了生物乙醇水相偶联提质合成高级醇燃料技术，针对生物乙醇缩合制高级醇中存在的贵金属催化剂成本较高及高级醇-水双相体系传质受限阻碍碳链增长的关键问题开展研究。项目研究了基于非贵金属Ni的乙醇水相偶联反应路径和和作用机制，明晰了以脱氢-羟醛缩合-加氢为主的氢转移主反应路径及重整、甲烷化等C-C断键副反应路径，揭示了金属Sn掺杂对高级醇合成的促进机制，取得了高级醇选择性达86.4%、C-C断键副产物选择性低至1.3%等技术突破。成功构建了高效的非贵金属Ni基双相乳化传质催化体系，制备了系列NiSn非贵金属和水滑石、碳(LDHs、C)材料相耦合的多功能两亲乳液催化剂，探索了乳化催化过程影响规律及调控机制，利用NiSn@C-MgO两亲反相乳液化催化体系的相转移催化、多相界面偶联反应策略强化偶联催化过程，有效提高了乙醇水相偶联过程中C6+高级醇的选择性至60.9%。项目评价了高级醇产品燃料化特性，初步打通了生物小分子醇水相提质合成高级醇燃料的新途径，为清洁替代燃料的发展应用提供新的基础理论和技术支撑。项目按计划完成了研究目标，发表学术期刊论文6篇，申请发明专利6项，其中3项授权，培养了青年骨干人才2人，硕士研究生2名。