生物质多孔碳基纳米催化材料定向构筑及其选择性催化裂解焦油机理

Tar formation is a key and urgent problem to be solved for the development biomass pyrolysis/gasification. Its efficient and low-cost catalytic conversion has significant influence on the safety of the system as well as energy conversion efficiency. In this project, a new tar selective catalytic decomposition method is proposed using porous carbon based catalytic material supporting metal nanoparticles which is directionally synthesize through biomass pyrolysis. The interaction mechanism of porous structure formation, metal nanoparticles evolution and surface organic functional groups variation will be studied during the preparation of the catalytic material. The main influencing factors and directional control characteristics of nanoparticles morphology and distribution will be investigated, and a practical method will be established for directional preparation of biomass carbon-based catalytic material. The mechanism of tar selective decomposition over biomass porous carbon based catalytic material will be investigated to clarify the synergistic mechanism of porous carbon adsorption and metal nanoparticles catalysis. The project also aims at revealing the global reaction mechanism of tar decomposition and determining key factors as well as regulation methods between the efficiency and selectivity of tar catalytic decomposition. The molecular dynamics model will be set up to study the tar catalytic decomposition on the surface of the catalyst as well as damage and inactivation process. New processes will be developed for strengthening the carbon based catalytic material structure and recycling of nanoparticles. We will also solve the key problems during the decomposition of tar such as the damage of catalytic materials, deactivation by coke deposition and regeneration of nanoparticles. The implementation of this project will develop a new technology for tar selective decomposition based on biomass carbon based nano metal catalytic materials, which will provide theoretical ideas and guidance for the conversion and treatment of biomass tar.

焦油是生物质热解气化技术亟需解决的关键问题，其高效低成本催化转化对于系统安全运行和提高能源转化效率具有重要影响。本项目提出生物质热解定向构筑多孔碳基纳米催化材料选择性催化裂解焦油的思路，探索多孔碳基体形成、纳米金属演变及官能团转化过程交互作用机制，明确纳米颗粒形态和分布的主要影响因素和定向调控特性，建立生物质多孔碳基纳米催化材料定向制备方法；研究催化材料对焦油选择性催化特性，阐明碳材料多孔吸附与纳米金属催化裂解协同作用机制，揭示焦油裂解全局反应机理,确定影响焦油裂解转化效率与选择性的关键因素和调控途径；构建催化表面表面焦油催化裂解与受损失活过程分子动力学模型，开发碳基催化材料结构强化和纳米金属循环再生工艺，解决催化材料反应受损、表面积碳和纳米颗粒失活等关键问题。通过项目研究，将获得基于生物质碳基纳米催化材料的选择性催化裂解焦油技术，为生物质焦油的转化治理提供理论思路和指导。

针对生物质热解气化过程中产生的焦油问题，项目提出了定向构筑生物质多孔碳基纳米催化材料实现对焦油的选择性催化裂解的研究思路。首先，研究了生物质热解过程碳基材料结构演变特性，设计了生物质活化辅助定向构筑多孔碳结构的方法，并表征分析了过渡金属引入对碳基机构的影响特性，获得了典型过渡金属纳米颗粒构筑及其与多孔碳基材料的交互作用关系。其次，研究了典型生物质活化碳基材料对焦油的催化特性，分析了焦油催化裂解过程产物生成规律和关键影响因素，并耦合碳基材料活化与过渡金属纳米颗粒构筑过程，实现了材料多孔结构特性和催化活性的协同增强，获得了显著的焦油催化活性和稳定性。再者，基于木质生物质原生结构开发了自模板炭化制备整体式碳基催化剂方法，保留了生物质生长过程中的天然孔道，并将其作为了金属单质和合金纳米颗粒的优良载体，构建了生物质整体式原生结构衍生碳基催化剂，实现了焦油在孔道内快速流通和扰动，有效降低了焦油催化裂解过程中扩散，从而抑制了积碳的产生。随后，为强化金属纳米颗粒抗积碳特性，研究提出了双金属复合纳米颗粒构筑方法，设计了生物质多孔碳基材料负载复合金属纳米颗粒，构建了一种生物质蜂窝状碳基结构负载Ni-Fe纳米颗粒催化剂，探究了其在催化裂解焦油过程中的抗积碳特性。为强化生物质碳基纳米催化材料的结构强度，构建了介孔分子筛包覆式碳硅核壳结构的催化剂制备方法，有效限定了金属纳米颗粒粒径尺寸并保护活性位点免受积碳团聚的影响。围绕焦油催化裂解反应过程，构建了焦油分子热裂解、蒸汽重整和催化裂解过程分子动力学模型，探讨了不同工况条件下典型焦油分子裂解和蒸汽重整过程主要产物释放特性，解析了典型催化位点在焦油催化裂解过程中的主要作用，获得了焦油裂解过程主要中间产物，推测了焦油催化裂解基本路径和关键影响机制。