多孔陶瓷球负载催化剂对生物质热裂解的影响规律研究

The scientific selection of catalysts is a very important and critical issue for the catalytic pyrolysis of biomass. Commercial catalysts such as calcined limestone and calcined dolomite with low mechanical strength are easily broken and formed into fragments, which will degrade the flow and the catalytic performance of catalysts in the fluidized bed. Therefore, the porous ceramic balls supported catalyst is proposed to solve the aforementioned problems. The porous ceramic balls, which have strong structure, can guarantee the catalysts to bear strong burst and long-term vibration in high temperature environments. In this research, the dynamics of mixed-flow and heat transferring of the porous ceramic balls and the biomass powder are studied, while the influences of particle sizes, the porosity of porous ceramic balls and fluidization velocity are taken into account. The analytical model between the above factors with the distribution of pyrolysis products is then established and utilized to study the regulation and control mechanism of the pyrolysis products during the catalytic pyrolysis of biomass. Finally, the behavior of carbon deposition and aging of the porous ceramic balls supported catalyst are investigated, aiming at verifying the effectiveness of the catalyst under a long-term run. The completion of this research will provide a theoretical and technical support to control the product distribution of the catalytic biomass pyrolysis and lay a good foundation to understand the behavior of the catalytic pyrolysis of biomass, optimize the pyrolysis liquefaction process and improve the quality of bio-oil.

催化剂的合理选用是生物质催化热裂解反应的重点和关键，针对煅烧白云石、煅烧石灰石等类型的催化剂存在机械强度低，容易破碎形成粉尘，从而影响床内流动和催化剂的催化效果等不足，提出多孔陶瓷球负载催化剂并以此作为流化床料的方法，保证催化剂能够在高温生物质热裂解气流中承受较强的冲击和长期反复的振动。项目着重研究在不同多孔陶瓷球粒径、气孔率和流化气速下，多孔陶瓷球与生物质粉在流化床内的混合流动和传热传质特性，并建立与生物质热裂解产物分布规律间的理论模型，研究生物质催化热裂解液化产物的调控机理。最后对多孔陶瓷球负载催化剂的积碳规律和老化特性进行研究，以检验所制得的多孔陶瓷球负载催化剂长时间运行的有效性。项目的完成将为生物质催化热裂解液化产物分布的调控机理提供理论和技术支持，对于掌握生物质催化热裂解规律、优化生物质裂解液化工艺、提高生物油的品质具有重要理论指导意义。

催化剂的合理选用是生物质催化热裂解反应的重点和关键，项目针对白云石等催化剂存在机械强度低，容易破碎形成粉尘，影响床内流动和催化效果等不足，开展了多孔陶瓷球负载催化剂的制备方法研究，探索了造孔剂含量对堆积密度、抗压强度、孔径大小和分布等参数的影响规律，确定了优化的制备工艺。利用示踪粒子（PIV）测试平台，开展了流化床内多孔陶瓷球（石英砂）与生物质粉的多相混合流动特性研究，揭示了气孔率、流化风速、质量比变化对床内颗粒分布及横向、纵向平均速度的影响规律。 完成了陶瓷球与生物质粉气固两相传热传质特性研究，基于欧拉双流体模型对导流旋风式生物质热解反应器内气固两相流场及混合时间进行分析，确定了反应器内生物质热裂解产物质量分数沿轴、径向分布规律。完成了负载催化剂（白云石、SBA-15、ZSM-5和ZSM-5/SBA-15复合催化剂）对生物质热裂解产物调控规律的研究，揭示了催化条件下生物油酸度，酸类、酮类和酚类物质含量、芳烃类化合物的变化规律。完成了催化剂（X%Ga-ZSM-5/SBA-15）的积碳、老化特性研究，确定了随Ga负载量的增加结焦量增加，结焦去除难易程度先增大后减小的变化规律。