用于甲烷二氧化碳重整的增强Ni-SiO2催化剂：还原-氧化-还原预处理,Applied Catalysis B: Environment and Energy

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用于甲烷二氧化碳重整的增强Ni-SiO2催化剂：还原-氧化-还原预处理
Applied Catalysis B: Environment and Energy ( IF 20.2 ) Pub Date : 2016-06-23 04:10:00
Emma C. Lovell, Andrew Fuller, Jason Scott, Rose Amal

此处介绍的工作评估了还原-氧化-还原（ROR）预处理对5％和10％Ni-SiO _{2的影响，这}是一种有效且廉价的增强甲烷二氧化碳重整催化剂的方法。将样品还原，氧化并随后再还原，并在每个步骤中分析Ni的沉积特征。结果表明，ROR处理降低了平均Ni沉积尺寸并改变了Ni与SiO ₂之间的相互作用，从而显着增强了催化性能。ROR预处理导致CH ₄转化率增加，其中最显着的是10％Ni-SiO ₂样品（800°C下从57％到69％），在还原样品和ROR预处理样品之间的碳形成量相当。在600°C的稳定性测试中，经过3-4小时的反应时间，由于积碳而使减少了10％的样品失活。相反，在600°C下，ROR样品在12h的时间范围内保持6h后仍保持稳定的转化率。此外，对于所有样品，ROR预处理都会导致化学计量比更高的H ₂/ CO比。Ni沉积物尺寸和结晶度的降低增加了转化率和选择性。这是由于更大的活性金属表面积用于转化，以及通过影响CO的解吸并减少大量NiO的发生而降低了甲烷分解的发生率以及降低了水煤气的逆反应。最终，ROR预处理为改进干重整催化剂提供了一种简单而廉价的方法。

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Enhancing Ni-SiO2 catalysts for the carbon dioxide reforming of methane: Reduction-oxidation-reduction pre-treatment

The work presented here evaluated the impact of reduction-oxidation-reduction (ROR) pre-treatment on 5 and 10% Ni-SiO₂ as an efficient and inexpensive manner of enhancing catalysts for the carbon dioxide reforming of methane. Samples were reduced, oxidised and subsequently re-reduced, with the Ni deposit characteristics being analysed at each step. It was demonstrated that ROR treatment decreased the average Ni deposit size and altered the interaction between the Ni and SiO₂, which significantly enhanced catalytic performance. ROR pre-treatment resulted in an increase in CH₄ conversion, most significantly for the 10% Ni-SiO₂ samples (from 57% to 69% at 800°C) with comparable carbon formation between the reduced and ROR pre-treated samples. During 600°C stability tests the 10% reduced samples deactivated, due to carbon build-up, after 3–4h reaction time. In contrast, at 600°C the ROR sample maintained stable conversion after 6h over a 12h time frame. Additionally, for all samples ROR pre-treatment resulted in a more stoichiometric H₂/CO ratio. The reduction in both Ni deposit size and crystallinity increased conversion and selectivity. This derived from a greater active metal surface area for conversion as well as a decrease in the prevalence of methane decomposition and the reverse water gas shift reaction by influencing the desorption of CO and lowering the occurrence of bulk NiO. Ultimately, ROR pre-treatment provides a simple and inexpensive means of improving dry reforming catalysts.

更新日期：2016-06-23

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