The use of ruthenium Y zeolite catalysts for the selective methanation of carbon monoxide

Ahmed, Zaheera

The use of ruthenium Y zeolite catalysts for the selective methanation of carbon monoxide

Master Thesis

2015

Publisher

University of Cape Town

Department

Department of Chemical Engineering

Faculty

Faculty of Engineering and the Built Environment

Abstract

Fuel processing is the conversion of hydrocarbons to produce a mixture of H2 and CO, whereby the H2 will be used in a PEMFC. CO needs to be removed as the tolerance level of the Pt based electro catalyst is only 10 ppm of CO. In order to lower the concentration from 1% post-WGS, to 10 ppm, CO can be converted to CH4 via selective methanation. A selective catalyst primarily methanates CO and inhibits the methanation of CO2 which results in the over consumption of H2. Common catalysts for SMET include Ru/Al2O3 and Ru/Y zeolites. This study involved the use of Ru/Y zeolite catalysts with loadings between 1 wt.%-5.4 wt.% Ru prepared via ion exchange, and a commercial 5 wt.% Ru/Al₂O3. These catalysts were tested in a fixed bed reactor at temperatures between 160°C and 210°C at various space velocities with a feed composition of 1% CO, 20% CO2, 10% H2O, 59% H2 and 10% Ar. The effects of loading, space velocity and reaction temperature on the CO conversion and CO selectivity were investigated. The 2.2 wt.% was found to be the optimum loading by displaying the highest selectivity of 72%, and 100% CO conversion at 170°C. The higher loadings produced large amounts of CH4 displaying lower selectivity, coupled with a high undesirable consumption of H2. The 1 wt.% Ru/Y zeolite showed low activity for SMET but was active for the WGS reaction. The 5 wt.% Ru/Al2O3 displayed the highest selectivity of 60%, and 100% CO conversion at 180°C.

Keywords

Chemical Engineering

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