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>The structural evolution of Mo2C and Mo2C/SiO2 under dry reforming of methane conditions: morphology and support effects
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The structural evolution of Mo2C and Mo2C/SiO2 under dry reforming of methane conditions: morphology and support effects
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机译：The structural evolution of Mo2C and Mo2C/SiO2 under dry reforming of methane conditions: morphology and support effects
The thermal carburization of MoO3 nanobelts (nb) and SiO2-supported MoO3 nanosheets under a 1 : 4 mixture of CH4 : H2 yields Mo2C-nb and Mo2C/SiO2. Following this process by in situ Mo K-edge X-ray absorption spectroscopy (XAS) reveals different carburization pathways for unsupported and supported MoO3. In particular, the carburization of α-MoO3-nb proceeds via MoO2, and that of MoO3/SiO2via the formation of highly dispersed MoOx species. Both Mo2C-nb and Mo2C/SiO2 catalyze the dry reforming of methane (DRM, 800 °C, 8 bar) but their catalytic stability differs. Mo2C-nb shows a stable performance when using a CH4-rich feed (CH4 : CO2 = 4 : 2), however deactivation due to the formation of MoO2 occurs for higher CO2 concentrations (CH4 : CO2 = 4 : 3). In contrast, Mo2C/SiO2 is notably more stable than Mo2C-nb under the CH4 : CO2 = 4 : 3 feed. The influence of the morphology of Mo2C and its dispersion on silica on the structural evolution of the catalysts under DRM is further studied by in situ Mo K-edge XAS. It is found that Mo2C/SiO2 features a higher resistance to oxidation under DRM than the highly crystalline unsupported Mo2C-nb and this correlates with an improved catalytic stability. Lastly, the oxidation of Mo in both Mo2C-nb and Mo2C/SiO2 under DRM conditions in the in situ XAS experiments leads to an increased activity of the competing reverse water gas shift reaction.
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机译：MoO3纳米带的热渗碳(nb)下,SiO2-supported MoO3 nanosheets 1: 4甲烷的混合物:H2收益率Mo2C-nb和Mo2C /二氧化矽。这个过程由原位莫K-edge x射线吸收光谱(xa)揭示了不同渗碳途径不受支持的MoO3支持。的α-MoO3-nb收益通过MoO2,MoO3 / SiO2via高度分散的形成MoOx物种。甲烷干重整(DRM, 800°C, 8条)但是他们的催化稳定性不同。显示了一个使用CH4-rich时性能稳定饲料(CH4 CO2 = 4: 2),然而失活由于MoO2出现更高的形成二氧化碳浓度(CH4 CO2 = 4: 3)。相反,Mo2C /二氧化硅是明显比更稳定Mo2C-nb下CH4 CO2 = 4: 3饲料。Mo2C及其形态的影响分散在二氧化硅结构进化催化剂在DRM的进一步研究原位莫K-edge xa。更高的抗氧化特性DRM的高度结晶不受支持的Mo2C-nb这与改进催化稳定性。DRM Mo2C-nb和Mo2C /二氧化矽导致原位xa的条件实验增加活动的反竞争水煤气转移反应。
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