双功能钙基催化剂的制备及其催化裂解生物质焦油制氢机理研究

The new technology of CaO-based chemical looping gasification, aiming to produce hydrogen from biomass, has caused extensive concern. However, the main problems to limit its industrial application are: refractory “heavy tar” and activity attenuation of the carrier. In view of the above problems, a modified calcium based dual-function catalyst, which can as a tar reforming catalyst and CO2 sorbent to enhance tar catalytic properties and reaction stability. The main study points are: the preparation and optimization method of this Ca-based dual-functional catalyst; seeking the catalytic cracking path of tar and its kinetics and thermodynamics mechanism during the biomass chemical looping gasification process; meanwhile, the change process of intermediate product during catalytic reaction and the effects of the main parameters, such as temperature, steam/biomass and residence time on tar components and hydrogen production efficiency will be investigated to clarify the mechanism of tar catalytic cracking and provide the theory basis of tar removal during chemical looping gasification process; also, further study of the recycling characteristics of the dual-functional catalyst in reaction process will be conducted; finally, through CLG experiments and Aspen Plus simulation, the dual-function of Ca-catalyst based chemical looping gasification technology for hydrogen production will be optimized. The research results can provide important scientific data and theoretical support for the development of biomass chemical looping gasification.

基于钙基CO2载体的生物质化学链气化是一项被广泛关注的生物质制氢新技术，限制其工业化应用的主要难点在于对“重焦油”难降解、载体活性衰减等问题。针对以上问题，本项目提出制备具有催化焦油制氢和原位吸收CO2双功能的钙基催化剂，增强其焦油催化性能及反应稳定性。重点研究双功能钙基催化剂的制备及优化方法，探寻生物质化学链气化过程中焦油催化裂解途径及热力学、动力学机制，考查催化反应过程中的中间产物变化过程，以及主要实验条件如温度、水蒸气/生物质比以及停留时间等对焦油含量组分、制氢效率的影响，以期阐释该催化剂对焦油裂解的催化机理，获得生物质化学链气化中焦油转化制氢运行工艺选择的理论依据；同时对该双功能催化剂在反应过程中的循环再生特性进行深入研究；最后通过CLG实验研究结合Aspen Plus仿真模拟，获得基于双功能钙基催化剂的生物质化学链循环制氢科学方法，为该技术的发展提供重要的基础科学数据和理论支撑。

目前氢气主要依靠化石能源生产，该制氢方法成本较高，污染环境并释放大量的二氧化碳。而生物质制氢具有可再生性、低污染等特点。基于钙基CO2载体的生物质化学链气化是一项被广泛关注的生物质制氢新技术，限制其工业化应用的主要难点在于对“重焦油”难降解、载体活性衰减等问题。针对以上问题，本项目提出制备具有催化焦油制氢和原位吸收CO2双功能的钙基催化剂，增强其焦油催化性能及反应稳定性。项目主要开展了双功能钙基催化剂的设计与优化制备研究；开展了主要工艺条件如温度、水蒸气/生物质比等对生物质焦油含量组分、制氢效率的影响研究；探讨了生物质化学链气化过程中双功能钙基催化剂对焦油的裂解作用机理；通过负载稀有金属、过渡金属等对催化剂进行了改性优化获得了良好的循环再生性能的双功能钙基催化剂；对双功能钙基催化剂同步实现CO2吸附捕获效果进行了分析；另外，在双功能钙基催化剂开发及CLG实验研究的基础上，利用Aspen Plus对吸收增强化学链水蒸气重整制备富氢合成气工艺进行了建模分析，探究了不同工艺参数对系统中产物分布及热负荷的影响。项目研究成果将为基于双功能钙基催化剂的生物质化学链循环制氢技术发展提供重要的基础科学数据和理论支撑。