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1.15】杨艳辉 教授
题目:Catalytic conversion of CO2 to fuel
 
2018-01-12 | 文章来源:先进炭材料研究部        【 】【打印】【关闭

狮子机森林舞会下载 www.bottors.com   题目:Catalytic conversion of CO2 to fuel

  报告人:杨艳辉 教授(南京工业大学)

  时间:1月15日(周一)10:00-11:30

  地点:李薰楼249会议室

  In the global attempt to reduce carbon footprint, the chemical and petrochemical industry faces the problem to replace the currently used fossil feedstock with renewable resources, reduce energy consumption and to intensify and integrate the processes to be more carbon efficient. In all three issues, catalysis will be the key to a successful transformation. Knowledge-based development and implementation of catalytic technology will help to process the novel feedstock, reduce the energy required for maintaining the desired process and improve the carbon efficiency of the targeted synthesis routes. In this seminar, two examples will be discussed to illustrate our efforts in the last year in CO2 utilization.

  The catalytic hydrogenation of CO2 under atmospheric pressure is a hot topic in CO2 utilization in which methanation and reverse water-gas shift (RWGS) serve two competing parallel pathways. Novel Ni-W-Mg mixed oxide catalysts (NiWMgOx) were prepared by homogeneous precipitation and attempted for the methanation of CO2. Adding W remarkably promoted the activity with improved stability, anti-CO-poisoning ability and resistance against coke formation compared to the undoped NiMgOx catalyst. The superior reactivity of monodentate formate towards hydrogenation than that of bidentate formate species was identified by DRIFTS analysis and the formation of more active monodentate formate species was indisputably facilitated by W additives, leading to the greatly enhanced catalytic activity. H2-TPR and CO2-TPD characterization showed that doping W increased the number of stable CO2 adsorption sites and helped in anchoring the Ni sites as a result of strengthened Ni-Mg interaction, both of which were responsible for the enhanced CO2 methanation activity and the improved resistance against sintering.

  The control mechanism of catalytic selectivity and structure-activity relation at atomic scale need further understanding. It has been suggested that the dispersion state and the size of metallic particles play a crucial role in determining CO2 conversion and selectivity as well as stability. However, these studies have not considered the possible effect of interface sites between metal and oxide support in selective hydrogenation of CO2. In this work, three structural configurations of monolayer, periphery and nanocluster in Ru/Al2O3 catalysts were obtained by control of Ru weight loadings, confirmed by the characterization results of the extended X-ray absorption fine structure, H2-O2 titration and diffuse reflectance infrared Fourier transform spectroscopy of CO adsorption. The kinetic data reveal the dependence of reaction rates for CO and CH4 formation with different apparent activation energies on the Ru surface structures. Theoretical calculations of Ru9/Al2O3 and Ru35/Al2O3 models demonstrate that monolayer Ru sites favor the RWGS route with a relatively low energy barrier for both CO2 activation and CO formation steps, while Ru nanoclusters prefer methanation route energetically. Moreover, the combination of theoretical calculations and experimental isotope-exchange measurements suggests that the interfacial O species in Ru-Al2O3 interfaces act a critical role in CO2 activation via exchanging with O atom in feeding CO2 and incorporating into the final hydrogenation products.

  

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