Carbon monoxide oxidation over CuO/CeO2 catalysts

Tang, Xiaolan; Zhang, Baocai; Li, Yong; Xu, Yide; Xin, Qin; Shen, Wenjie

doi:10.1016/j.cattod.2004.06.040

Cited by 208 publications

(109 citation statements)

References 22 publications

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“…Temperature Programmed Reduction (H 2 -TPR) Figure 3 shows the H 2 -temperature programmed reduction profiles of the analyzed samples between 50 • C and 500 • C. On the bare cerium oxide support, the H 2 consumption starts at around 350 • C, due to the partial reduction of the CeO 2 surface oxygen [12,13]. The reduction of bulk oxygen was reported to take place at temperatures higher than 700 • C [32] and, therefore, is not visible in the TPR curve of Figure 3. The profile of the Ru/CeO 2 sample displays two reduction peaks at 165 • C and 190 • C and a shoulder at ca.…”

Section: Catalysts Characterizationmentioning

confidence: 99%

Ru–Pd Bimetallic Catalysts Supported on CeO2-MnOX Oxides as Efficient Systems for H2 Purification through CO Preferential Oxidation

et al. 2018

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Abstract:The catalytic performances of Ru/ceria-based catalysts in the CO preferential oxidation (CO-PROX) reaction are discussed here. Specifically, the effect of the addition of different oxides to Ru/CeO 2 has been assessed. The Ru/CeO 2 -MnO x system showed the best performance in the 80-120 • C temperature range, advantageous for polymer-electrolyte membrane fuel cell (PEMFC) applications. Furthermore, the influence of the addition of different metals to this mixed oxide system has been evaluated. The bimetallic Ru-Pd/CeO 2 -MnO x catalyst exhibited the highest yield to CO 2 (75%) at 120 • C whereas the monometallic Ru/CeO 2 -MnO x sample was that one with the highest CO 2 yield (60%) at 100 • C. The characterization data (H 2 -temperature programmed reduction (H 2 -TPR), X-ray diffraction (XRD), N 2 adsorption-desorption, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS)) pointed out that the co-presence of manganese oxide and ruthenium enhances the mobility/reactivity of surface ceria oxygens accounting for the good CO-PROX performance of this system. Reducible oxides as CeO 2 and MnO x , in fact, play two important functions, namely weakening the CO adsorption on the metal active sites and providing additional sites for adsorption/activation of O 2 , thus changing the mechanism from competitive Langmuir-Hinshelwood into non-competitive one-step dual site Langmuir-Hinshelwood/Mars-van Krevelen. As confirmed by H 2 -TPR and XPS measurements, these features are boosted by the simultaneous presence of ruthenium and palladium. The strong reciprocal interaction of these metals between them and with the CeO 2 -MnO x support was assumed to be responsible of the promoted reducibility/reactivity of CeO 2 oxygens, thus resulting in the best CO-PROX efficiency at low temperature of the Ru-Pd/CeO 2 -MnO x catalyst. The higher selectivity to CO 2 found on the Ru-Pd system, which reduces the undesired H 2 consumption, represents a promising result of this research, being one of the key aims of the design of CO-PROX catalysts.

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Section: Catalysts Characterizationmentioning

confidence: 99%

Ru–Pd Bimetallic Catalysts Supported on CeO2-MnOX Oxides as Efficient Systems for H2 Purification through CO Preferential Oxidation

et al. 2018

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“…The different interaction between the MOx and CeO2, as indicated by their distinct reduction behaviours of the MOx/CeO2 samples, would determine the dispersion of the corresponding metals on CeO2−δ and thus affect their ability in hydrogen activation (see Section 2.4 for the H2-TPD analysis). The two broad reduction peaks appearing at 530 and 705 °C for CeO2 are attributed to the respective reductions of surface oxygen species and the bulk lattice oxygen within ceria [32]. However, for the three MOx/CeO2 samples, their reduction peaks due to the removal of lattice oxygen from the CeO2 support are displayed in a similar temperature region (600~800 °C), suggesting that the involved MOx species slightly impact the reducibility of the lattice oxygen of CeO2.…”

Section: Reduction Behaviour Of the Mox/ceo2 Catalyst Precursorsmentioning

confidence: 87%

“…The D and 2LO bands are related to the Ovac that originated from reducing Ce 4+ to Ce 3+ . Compared to CeO2, MOx/CeO2 samples show broader and stronger vibrations in the D bands and 2LO modes, suggesting that the loading of MOx species facilitates the creation of Ovac thanks to metal substitution of lattice Ce, which is in good The two broad reduction peaks appearing at 530 and 705 • C for CeO 2 are attributed to the respective reductions of surface oxygen species and the bulk lattice oxygen within ceria [32]. However, for the three MO x /CeO 2 samples, their reduction peaks due to the removal of lattice oxygen from the CeO 2 support are displayed in a similar temperature region (600~800 • C), suggesting that the involved MO x species slightly impact the reducibility of the lattice oxygen of CeO 2 .…”

Section: Surface Structural Analysismentioning

confidence: 97%

The Catalytic Hydrogenation of Maleic Anhydride on CeO2−δ-Supported Transition Metal Catalysts

et al. 2017

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Abstract:The proper selection of transition metals and support is pivotal to the design of active and selective catalysts for maleic anhydride hydrogenation (MAH). Herein, the M/CeO 2−δ (M = Co, Ni, Cu, respectively) catalysts with pre-optimised metal loading of 10 wt % were prepared via a wet impregnation method and well characterized to corroborate their MAH performance with the properties of metal, support and the M/CeO 2−δ catalysts. The results revealed that the metal dispersion on the catalyst declines in the order of Ni/CeO 2−δ > Co/CeO 2−δ > Cu/CeO 2−δ , similar to the apparent activity for maleic anhydride (MA) transformation to succinic anhydride (SA). The hydrogenolysis of SA to γ-butyrolactone (GBL) occurs on Ni/CeO 2−δ and Co/CeO 2−δ only when the MA → SA transformation completing. The Ni/CeO 2−δ displays superior activity and selectivity to Co/CeO 2−δ in both MA → SA and SA → GBL reactions, while the Cu/CeO 2−δ and CeO 2−δ are both inert for SA → GBL hydrogenolysis. The MA hydrogenation to SA follows the first order kinetic law on the Ni/CeO 2−δ and Co/CeO 2−δ catalysts yet a more complex kinetic characteristics observed on the Cu/CeO 2−δ . The distinct catalytic hydrogenation behaviours of the M/CeO 2−δ catalysts are assigned to the synergism of dispersion and electronic configuration of the transition metals and oxygen vacancies.

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“…Apenas os catalisadores CuO/CeO 2 (5%) e CuO/TiO 2 (5%) mostram três picos de redução referentes ao metal, sendo que o pico a menor temperatura corresponde à redução das espécies de CuO com partículas pequenas ligadas à superfície do suporte e os picos em temperaturas maiores são devidos à redução do CuO bulk, presente em partículas grandes ligadas ao suporte. 16,[26][27][28] Nos catalisadores suportados em céria e céria/titânia, além dos picos de redução referentes ao metal, outro pico, a temperaturas maiores, pode ser observado e deve-se à redução do óxido de cério mássico.…”

Section: Redução a Temperatura Programadaunclassified

Estudo da reação de oxidação preferencial do co sobre o sistema CuO/CeO2-TiO2

Maciel

Assaf

2010

Quím. Nova

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Recebido em 24/2/10; aceito em 21/6/10; publicado na web em 17/9/10 CO PREFERENTIAL OXIDATION ON CuO/CeO 2 -TiO 2 SYSTEM. Cu catalysts supported on CeO 2 , TiO 2 and CeO 2 /TiO 2 were prepared by precipitation method and used for preferential oxidation of carbon monoxide contained in a hydrogen flow generated by methane steam reforming. The samples were characterized by XRD, BET and TPR techniques. The catalytic properties were studied in the 50-330ºC range by using a quartz micro-reactor vertically positioned on an electrical furnace. The results showed that the small copper particles generated with the lower metal content are the most easily reducible and give the best catalytic performance. In respect of support effect, the strong metal-support interaction and the redox characteristics of the CuO x -CeO 2 series resulted in the best catalytic results, especially with the sample with 1% copper content.Keywords: PROX-CO; copper; ceria. INTRODUÇÃOEstudos recentes relacionados com a tecnologia de células a combustível, especialmente aqueles envolvendo membranas poliméricas de troca iônica (PEMFC), têm estimulado o interesse pela reação de oxidação preferencial do monóxido de carbono (PROX-CO). Uma vez que as células PEMFC utilizam como fonte de energia o hidrogênio com elevada pureza, a reação de PROX-CO apresenta-se como um meio de purificar o hidrogênio produzido pelas reações de reforma do metano. 1-10O método convencional de produção de hidrogênio combina as reações de reforma a vapor do metano com a reação de deslocamento gás-água (WGS -water gas shift reaction), e os gases gerados apresentam a seguinte composição aproximada: 45% H 2 , 25% CO 2 , 10% H 2 O, 20% N 2 e 0,5-1% CO.1,2 Essa quantidade de CO presente no gás de reforma precisa ser removida devido a efeitos adversos que provoca no anodo das células PEMFC, ocasionando a desativação do eletrocatalisador de Pt que está depositado sobre uma camada difusora à base de carbono e teflon (PTFE). Assim, é necessária a remoção do CO, reduzindo seus níveis para valores menores que 10 ppm.1 Para alcançar esse nível de concentração, alguns caminhos são estudados: metanação catalítica, separação por membrana de Pd e oxidação preferencial do CO (PROX-CO).1,11 Destas, a PROX é a que oferece menor custo na redução dos níveis de CO sem o consumo excessivo de hidrogênio. 1Juntamente com a PROX-CO (Equação 1), a reação indesejada de oxidação do hidrogênio (Equação 2) pode ocorrer, diminuindo a eficiência do processo.(1)O catalisador convencional para a PROX-CO é Pt/g-Al 2 O 3 , porém diferentes tipos de catalisadores mostraram ser eficientes para a reação. Estes podem envolver fases ativas de metais nobres suportados, como platina e ouro, ou ainda metais não-nobres, como o cobre suportado em óxidos. 1,2Os catalisadores de metais nobres exibem boa atividade catalí-tica em temperaturas entre 150-250 ºC mas, além de apresentarem um alto custo, no geral, são pouco seletivos.3 Por outro lado, alguns catalisadores de metais não nobres suportados em óxidos têm se mostrado efic...

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Carbon monoxide oxidation over CuO/CeO2 catalysts

Cited by 208 publications

References 22 publications

Ru–Pd Bimetallic Catalysts Supported on CeO2-MnOX Oxides as Efficient Systems for H2 Purification through CO Preferential Oxidation

Ru–Pd Bimetallic Catalysts Supported on CeO2-MnOX Oxides as Efficient Systems for H2 Purification through CO Preferential Oxidation

The Catalytic Hydrogenation of Maleic Anhydride on CeO2−δ-Supported Transition Metal Catalysts

Estudo da reação de oxidação preferencial do co sobre o sistema CuO/CeO2-TiO2

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