生物质热解气催化重整过程温室气体调变机制研究

Reforming of biomass pyrolysis gas with water vapors has the functions of both reducing the greenhouse gas component and modulating the carbon-hydrogen ratio, effectively improving the quality of biomass synthetic gas. This is one of effective dimethyl-ether production methods, and is expected to be applied widely. In this paper, basic scientific issues of high-performance catalyst selection, effective greenhouse-gas component modulation, and multi-element catalytic reforming and coupling mechanism in the new method, were studied. With combination of phase representation and numerical simulation methods, supported catalysts were evaluated for their gaseous products quality and stability, to select a high-performance catalyst suitable for synthetic gas production by catalytic reforming biomass pyrolysis gas with water vapors; by means of synergism between methane, carbon dioxide and water vapor, the research of reforming modulation features and thermal effect was performed, in order to identify synergistic effect and heat transfer rule of multi-element reforming reactions in different process conditions and thus determine their optimal combinations for system operation; the characterization for structures and properties of supported catalysts was performed to identify conclusive reaction-rate steps in complex multi-element reforming reaction systems, and uncover the coupling mechanism of catalytic reforming reactions with methane, carbon dioxide and water vapor, providing theoretic basis for application of the biomass pyrolysis gas reforming modulation technology in the reaction condition of water vapors.

水蒸气重整生物质热解气，既达到温室气体组分有效降低，又实现灵活调变碳氢比，有效提高生物质合成气品质，是制备二甲醚的有效途径之一，具有广阔发展前景。本项目针对这种新方法中存在的高性能催化剂筛选、温室气体组分有效调变、多元催化重整耦合机理等基础科学问题开展研究。采用物相表征和数值模拟等方法，评价系列负载型催化剂的气相产物品质及稳定性，筛选出适合蒸汽重整生物质热解气制备合成气的高性能催化剂；利用甲烷、二氧化碳和水蒸气的协同作用，通过重整调变特性和热效应研究，明确多元重整反应在不同工艺条件下的协同效应及热量传递规律，确定系统运行的优化组合条件；通过负载型催化剂的结构和物性表征，考察甲烷、二氧化碳和水蒸气在催化剂表面的活化方式及演变历程，明确复杂多元重整反应体系的决定性反应速率步骤，揭示甲烷、二氧化碳和水蒸气催化重整反应过程的耦合机理，为水蒸气气氛下生物质燃气重整调变技术的应用提供理论支撑。

采用生物质热解或者气化制备合成气可以使大量的生物质资源得到充分的有效利用，同时也可以在一定程度上缓解日益紧张的能源危机。水蒸气重整生物质热解气，既达到温室气体组分有效降低，又实现灵活调变碳氢比，有效提高生物质合成气品质，是制备二甲醚的有效途径之一，具有广阔发展前景。本项目针对这种新方法开展了高性能催化剂筛选、温室气体组分有效调变、多元催化重整耦合机理等一系列研究。筛选出适合蒸汽重整生物质热解气制备合成气的高性能催化剂。利用甲烷、二氧化碳和水蒸气的协同作用，通过重整调变特性和热效应研究，明确多元重整反应在不同工艺条件下的协同效应及热量传递规律，确定系统运行的优化组合条件。通过负载型催化剂的结构和物性表征，考察甲烷、二氧化碳和水蒸气在催化剂表面的活化方式及演变历程，明确复杂多元重整反应体系的决定性反应速率步骤，揭示甲烷、二氧化碳和水蒸气催化重整反应过程的耦合机理。研究结果表明γ-A12O3为载体的负载型镍基催化剂具有最佳活性，镍负载量为10%时较适合用于生物质热解气催化重整过程。最优系统运行条件为反应时间为20min，反应温度为850℃，水蒸气与生物质质量比为1，催化剂与生物质质量比为0.5。在最优工况下，合成气中H2/CO为1.41,温室气体含量（CO2+CH4）为20.39%，碳转化率为86.07%；装置产气率为1.15Nm3/kg，气化效率为79.61%。催化剂的添加明显降低了合成气中温室气体的含量，提高了合成气的品质。项目研究将为水蒸气气氛下生物质燃气重整调变技术的应用提供参考。