Detalhes do Documento

Carbon formation and CO methanation on silica-supported nickel and nickel–coppe...

Autor(es): Tavares, M. T. cv logo 1 ; Alstrup, I. cv logo 2 ; Bernardo, C. A. cv logo 3 ; Rostrup-Nielsen, J. R. cv logo 4

Data: 1996

Identificador Persistente: http://hdl.handle.net/1822/3698

Origem: RepositóriUM - Universidade do Minho


Descrição
The steady-state rates of simultaneous carbon formation and methanation on silica-supported nickel and nickel-copper catalysts in CO + H 2 gas mixtures have been measured in the partial pressure range 10-30 kPa and the temperature range 583-873 K. The steady-state kinetic results for carbon formation can be explained by a model previously used for carbon formation in pure CO gas, but modified to take into account the influence of hydrogen. Comparisons between the results for Ni/SiO 2 , Ni 0.99 Cu 0.01 /SiO 2 , Ni 0.9 Cu 0.1 /SiO 2 , and Ni 0.75 Cu 0.25 /SiO 2 show that the specific rate of carbon formation is increased when 1 at.% of Cu is added to a nickel catalyst, but that the rate decreases when the Cu content is increased to 10 at.%, and that no carbon formation is seen for the Ni 0.75 Cu 0.25 /SiO 2 catalyst. The addition of a small amount of Cu, on the other hand, decreases the methanation rate while at higher Cu contents the rate goes up again and a maximum is observed at about 7 at.% Cu. Thus a simple ensemble model cannot explain the influence of copper on the rate of carbon formation or methanation. Comparison of carbon formation and methanation rates for the Ni/SiO 2 and the Ni 0.99 Cu 0.01 /SiO 2 catalysts indicates that the two reactions have different rate-controlling steps and that the carbon formation influences the methanation rate mainly through poisoning of the catalysts.
Tipo de Documento Artigo
Idioma Inglês
delicious logo  facebook logo  linkedin logo  twitter logo 
degois logo
mendeley logo

Documentos Relacionados



    Financiadores do RCAAP

Fundação para a Ciência e a Tecnologia Universidade do Minho   Governo Português Ministério da Educação e Ciência Programa Operacional da Sociedade do Conhecimento União Europeia