The polymer electrolyte fuel cell is a most promising system for residential power generation. Because hydrogen produced via fuel processing of municipal gas contains around 0.5% CO, deep removal of CO is essential. Selective CO methanation (SCM) is attracting attention as a new CO removal method because of its potential for drastic cost reduction. Requirements for an SCM catalyst are high activity for CO methanation and suppression of the CO2methanation and reverse water-gas shift (RWGS) reactions. When RWGS progresses, outlet CO concentration increases significantly. Recently, our group reported that the catalytic activity and selectivity of a Ni-alumina-based catalyst were remarkably improved by V addition. However, it is not sufficiently understood why the catalytic properties were improved. The aim of this study is the elucidation of the essential reason for the improvement, which may relate to the structure and chemical states of the vanadium species. Figure 1 shows the temperature dependence of outlet CO concentration during SCM reaction measurements. It was found that an increase in the CO concentration due to the RWGS in the high temperature region was suppressed by V addition. Detailed analyses of the catalysts by using XPS, STEM-EDS and XRD measurements revealed a V oxide species located in the vicinity of Ni particles on the alumina support. The relation between the structure of the active sites and the catalytic properties will be discussed in detail.

Effect of vanadium addition on the catalytic activity of Ni/alumina for selective CO methanation

248th National Meeting (2014)

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