Effect of support oxygen storage capacity on the catalytic performance of Rh nanoparticles for CO2 reforming of methane
Effect of support oxygen storage capacity on the catalytic performance of Rh nanoparticles for CO2 reforming of methane
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DOI：
10.1016/j.apcatb.2018.10.048
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发表时间：
2019-04-01
影响因子：
22.1
通讯作者：
Lambert, Richard M.
中科院分区：
文献类型：
--
作者：
Yentekakis, Ioannis V.;Goula, Grammatiki;Lambert, Richard M.
考察了金属氧化物载体对铑催化甲烷干重整反应的活性、选择性、抗积炭性和高温氧化老化性的影响。在400-750 ℃的温度区间内，在积分和微分反应条件下，研究了三种负载在氧化物上的Rh催化剂，所述氧化物具有非常不同的储氧能力和稳定性（γ-Al 2 O3、氧化铝-氧化铈-氧化锆（ACZ）和氧化铈-氧化锆（CZ））。ACZ和CZ促进CO2转化，产生富CO合成气。这些材料的详细表征，包括通过反应池和光谱仪室之间的样品转移获得的最先进的XPS测量，提供了对决定催化性能的因素的清晰洞察。通过反应后XPS检测到的主要Rh物种是Rh，其相对含量按Rh/CZ（100%）> Rh/ACZ（72%）> Fth/γ Al_2O_3（55%）的顺序降低。催化活性遵循相同的顺序，明确表明Rh确实是关键活性位点。此外，CZ的存在下，在支持服务，以保持Rh在金属状态和最小化碳沉积在反应条件下。碳沉积，低在所有情况下，增加的顺序Rh/CZ < Rh/ACZ < Rh/γ-Al 2 O3符合双功能反应机制，其中不稳定的晶格O2-的反向溢出有助于碳氧化，Rh的稳定和其表面化学的修改;在支持提供中心的解离吸附CO2的所得O空位。用含CZ的样品观察到的较低的表观活化能表明CZ是用于低温DRM的有前景的支撑组分。
The effects of the metal oxide support on the activity, selectivity, resistance to carbon deposition and high temperature oxidative aging on the Rh-catalyzed dry reforming of methane (DRM) were investigated. Three Rh catalysts supported on oxides characterized by very different oxygen storage capacities and labilities (gamma-Al2O3, alumina-ceria-zirconia (ACZ) and ceria-zirconia (CZ)) were studied in the temperature interval 400-750 degrees C under both integral and differential reaction conditions. ACZ and CZ promoted CO2 conversion, yielding CO enriched synthesis gas. Detailed characterization of these materials, including state of the art XPS measurements obtained via sample transfer between reaction cell and spectrometer chamber, provided clear insight into the factors that determine catalytic performance. The principal Rh species detected by post reaction XPS was Rh, its relative content decreasing in the order Rh/CZ(100%) > Rh/ACZ(72%) > Fth/gamma Al2O3(55%). The catalytic activity followed the same order, demonstrating unambiguously that Rh is indeed the key active site. Moreover, the presence of CZ in the support served to maintain Rh in the metallic state and minimize carbon deposition under reaction conditions. Carbon deposition, low in all cases, increased in the order Rh/CZ < Rh/ACZ < Rh/gamma-Al2O3 consistent with a bi-functional reaction mechanism whereby backspillover of labile lattice O2- contributes to carbon oxidation, stabilization of Rh and modification of its surface chemistry; the resulting O vacancies in the support providing centers for dissociative adsorption of CO2. The lower apparent activation energy observed with CZ-containing samples suggests that CZ is a promising support component for use in low temperature DRM.