镧修饰的有序介孔γ-Al2O3负载CaO固体催化剂优化制备及催化酯交换生产生物柴油的分子模拟

Calcium-based heterogeneous base catalysts are confronted with tedious mass transfer resistance, leaching into the liquid reagent and sensitiveness to free fatty acids (FFAs) in the feedstock. To solve these problems, calcium catalysts supported on ordered mesoporous γ-alumina (OMA) with lanthanum modification (La-Ca/OMA) are proposed in this project. It is hoped mass transfer resistance would be relaxed due to the mesoporous channel of OMA, stability of calcium active sites would be consolidated as the synergistic effect between calcium and OMA, and antipoisoning ability of calcium to FFAs would be strengthened for esterification catalyzed by lanthanum. Experimental research with molecular simulation is presented to reveal the synergistic effects among calcium, lanthanum and OMA on the microstructure characteristics, capillary chemistry and surface electronic properties. Adsorption behavior of reactant molecule on catalyst surface would be explored and the potential reaction routes would also be optimized, where thus nature of the La-Ca/OMA catalyzed transesterification would be explained. Also, mass transfer property by means of mesoporous channel in the La-Ca/OMA catalyzed transesterification would be investigated and chemical reaction kinetic parameters with consideration of the intermediates would be calculated based on the catalytic model deduced from molecular simulation. Fundamental theory of transesterification catalyzed by calcium heterogeneous base catalysts would be developed and enriched to promote the commercialization of biodiesel production in our country.

针对钙基固体碱催化酯交换传质阻力大、活性位易流失、对原料油酸成分敏感等问题，项目提出镧修饰有序介孔γ-氧化铝OMA负载CaO固体催化剂La-Ca/OMA优化制备的研究思路，有望发挥OMA孔道优势以减小传质阻力、借助钙铝耦合以提高Ca稳定性、依靠镧催化酯化以增强Ca抗酸皂化中毒的能力。项目采用实验与分子模拟相结合的研究手段，将探究活性成分Ca、助剂La、载体OMA协同作用对La-Ca/OMA微观结构特征、表面化学特性及表面电子性质的影响规律，并通过研究反应物分子在催化剂表面的吸附行为、催化酯交换的反应路径优化，在埃纳尺度层面上揭示La-Ca/OMA催化酯交换的过程本质，同时将分析介孔特质的La-Ca/OMA催化酯交换的传质过程，并基于分子模拟所得催化模型，计算考虑过程产物的化学反应动力学参数。项目将丰富和发展钙基固体碱催化酯交换的基础理论，并积极推动我国生物柴油生产的产业化进程。

以生物柴油为代表的生物质能是我国积极稳妥推进碳达峰碳中和的重要组成部分，钙基固体碱催化酯交换性能强且易与产物分离，比现有均相碱催化剂更具商业化应用前景。.针对钙基固体碱催化酯交换存在的传质阻力大、活性位易流失以及对原料油自由脂肪酸敏感等问题，本项目通过优化孔径分布、复合金属活性位、载体与活性位化学键合以及双性位助剂掺杂改性等方法，结合系统的表征手段，揭示了催化剂成分、合成方法及参数等对催化剂孔径、酸碱活性位分布及活性位浸出的影响规律与作用机制，明确了适于大分子甘油三酸酯酯交换生产生物柴油的负载型固体催化剂的制备技术路线，获得了传质阻力小、催化性能强、重复使用稳定性高并且对原料油所含自由脂肪酸适应性强的镧钙系铝基负载型固体催化剂。.明确了固体碱催化酯交换生产生物柴油的传质过程，基于双膜理论，计算获得了甲醇连续相传质系数、油脂分散相传质系数和催化剂表面固相传质系数，获得了固体碱催化酯交换生产生物柴油的总传质系数，计算获得了基于质量守恒定律的固体碱催化酯交换生产生物柴油化学反应动力学控制区的活化能和指前因子等动力学参数。.基于分子模拟，讨论了醇、酯等酯交换反应物在固体催化剂表面的吸附位点和吸附状态，探究了醇在活性位表面预吸附对酯等酯交换反应物吸附效果的影响机制，分析了金属氧化物复合、过渡元素掺杂改性对固体酯交换催化剂效果的作用机制，研究复合金属氧化物和掺杂改性助剂的种类与数量的作用规律，明确了助剂改性对碱土系铝基负载型固体酯交换催化剂性能的影响，从分子层面上揭示了催化酯交换法生产生物柴油的过程本质，为酯交换催化剂的高效设计提供了理论指导。.基于本项目研究，项目负责人以独立通讯作者发表论文21篇（含在线发表论文1篇），其中，SCI论文17篇、EI论文3篇，以第一完成人获授权发明专利5项，以指导教师身份培养毕业博士生1人、毕业硕士生8人。