title: Kinetic studies of CO2methanation over a Ni/γ-Al2O3catalyst.
abstract: The production of methane by reacting CO2with H2(CO2methanation) has the potential for producing synthetic natural gas, which could be exported using the existing infrastructure for the distribution of natural gas. The methanation of CO2was investigated over a wide range of partial pressures of products and reactants using (i) a gradientless, spinning-basket reactor operated in batch mode and (ii) a laboratory-scale packed bed reactor operated continuously. The rate and selectivity of CO2methanation, using a 12 wt% Ni/γ-Al2O3catalyst, were explored at temperatures 445-497 K and pressures up to 20 bar. Research with the batch reactor showed that the rate increased with increasing partial pressures of H2and CO2when the partial pressures of these reactants were low; however, the rate of reaction was found to be insensitive to changes in the partial pressures of H2and CO2when their partial pressures were high. A convenient method of determining the effect of H2O on the rate of reaction was also developed using the batch reactor and the inhibitory effect of H2O on CO2methanation was quantified. The kinetic measurements were compared with a mathematical model of the reactor, in which different kinetic expressions were explored. The kinetics of the reaction were found to be consistent with a mechanism in which adsorbed CO2dissociated to adsorbed CO and O on the surface of the catalyst with the rate-limiting step being the subsequent dissociation of adsorbed CO. The ability of the kinetic expressions to predict the results from the continuous, packed-bed reactor was explored, with some discrepancies discussed.
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK. rah75@cam.ac.uk.
authors.forename: R A
authors.initials: RA
authors.lastname: Hubble
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK. rah75@cam.ac.uk.
authors.forename: J Y
authors.initials: JY
authors.lastname: Lim
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB2 3RA, UK. rah75@cam.ac.uk.
authors.forename: J S
authors.initials: JS
authors.lastname: Dennis