基于介孔CeO2限域纳米VIII簇金属的新金属载体作用和表面等离子体效应的太阳光驱动催化干法甲烷重整

Both the efficient conversion of natural gas and the emission reduction of CO2 are national important strategic needs. The dry reforming of methane, i.e. the reaction of CO2 and CH4 to produce syngas, provides very attractive approach for solving the important strategic needs. However, the dry reforming of methane must process at high temperature, resulting in high energy consumption and catalyst deactivation due to the sintering and carbon deposit. It is very challenging task how to solve these problems. In the present proposal, nanoparticles of VIII group metals (Me) with the catalytic activity for the dry reforming of methane will be partially confined in the mespores of mesoporous CeO2 to efficiently inhibit sintering of the VIII group metal nanoparticles. This partial confinement will result in the improvement of the activity and reverse spillover of the lattice oxygen of CeO2 around the Me/CeO2 interface due to the presence of the novel metal-support interaction found in our previous work, thus significantly increasing the catalytic activity and resistance to carbon deposit. Meanwhile, solar light driven catalytic dry reforming of methane with high efficiency will be realized by utilizing the synergetic effect between the solar light driven therocatalysis and the photoactivation of CH4 and CO2, which changes the activation and reaction pathway of CH4 and CO2, due to the surface plasma effect of the VIII group metal nanoparticles confined in mesoporous CeO2. We will put deep physical insight into the effect of the nano confinement and solar light irradiation on the catalytic property. The present proposal will provide novel energy-saving approach and principle of designing catalysts for the efficient catalytic dry reforming of methane.

天然气有效转化和CO2减排是国家重大战略需求。干法甲烷重整，即CO2与甲烷反应生成合成气，为该重大需求的解决提供了极具吸引力的方法。但该反应须在高温下进行，能耗高、催化剂因高温烧结和积碳易失活，如何解决这些问题是极具挑战性的课题。本项目提出将具有干法甲烷重整催化活性的第Ⅷ簇金属纳米颗粒(Me)部分限域于介孔CeO2中，有效阻止催化剂高温烧结，利用所得Me/CeO2纳米复合催化剂存在的新金属-载体相互作用，提高界面区域CeO2晶格氧的活性和反溢流能力，从而显著提高其催化活性和抗积碳能力；同时利用第Ⅷ簇金属纳米颗粒的表面等离子体吸收导致的光致热催化和CH4、CO2分子在这些复合催化剂上的光活化之间的协同作用，改变这些分子的活化、反应机制，实现高效太阳光驱动干法甲烷重整，并揭示纳米限域作用和光照射对这些复合催化剂催化性能影响的本质。本项目将为催化干法甲烷重整提供节能新方法和催化剂设计新原理。

海量温室气体CO2排放造成的严重环境问题和能源短缺是事关人类社会可持续发展的重大战略问题。光催化CO2还原制燃料为这两个问题的解决提供了有前景的方法，但该方法存在燃料生成速率和太阳能至化学能转化效率低等很难解决的两大挑战。本项目以资源丰富的天然气为原料，发展了聚焦太阳光驱动干法甲烷重整（CH4 + CO2 = 2H2 + 2CO）新方法，既实现CO2的高效催化还原，又实现太阳能至化学能的高效转化存储，大幅度提高了燃料生成速率和太阳能至化学能转化效率。发现了基于第VIII簇金属纳米颗粒表面等离子吸收和热催化活性的光致热催化新机制，以及不同于半导体光催化的光活化新效应，显著提高了催化活性。研发了介孔CeO2部分限域Pt纳米颗粒，Ni/CeO2纳米复合催化剂，团簇CeO2、SiO2团簇表面修饰Ni纳米颗粒，Co掺杂Al2O3负载Co纳米颗粒、Ni掺杂Al2O3负载Ni纳米颗粒等第VIII簇金属纳米结构催化新材料。这些纳米结构催化新材料在聚焦太阳光照射下对干法甲烷重整具有优良催化活性和很高的太阳能至化学能转化效率。通过上述纳米结构新材料的设计，显著抑制了积碳副反应的发生，大幅度降低了积碳速率，从而使这些材料具有良好的光热催化稳定性。揭示了介孔CeO2、Co-Al2O3及Ni-Al2O3的活泼晶格氧参与碳物种的氧化，CeO2团簇、SiO2团簇表面修饰Ni纳米颗粒降低碳物种氧化的活化能等大幅度降低积碳速率、提高催化稳定性的机制。本项目为CO2减排和太阳能利用提供了新方法和催化剂设计新原理。本项目先后在Energy Environ. Sci.、Adv. Energy Mater.、Appl. Catal. B 、J. Mater. Chem. A、Green Chem.等国际重要期刊发表SCI论文22篇,申请国家发明专利2项，其中一项获授权，圆满地完成了项目的计划任务和目标。