Structured catalysts with high thermoconductive properties for the intensification of Water Gas Shift process

The influence of the thermal properties of structured carriers on the performance of a highly active catalytic formulation, was investigated in the Water Gas Shift (WGS) process. Some aluminum foam structured catalysts were prepared by charging the carriers with a platinumiceria/alumina-washcoat formulation; the catalytic performance were evaluated by providing a gaseous mixture, whose composition was chosen on the basis of a typical steam/carbon monoxide ratio at the outlet of a reformer. The activity of the structured catalysts and the thermal profile of the catalytic bed, were compared to those of a powder catalyst with the same composition of the washcoat formulation, in quasi-adiabatic condition, under equal conditions in terms of inlet temperature and weight hourly space velocity (WHSV). The experimental results showed much better performances for the structured catalysts, both in terms of CO conversion and temperature difference between the inlet and the outlet of the catalytic bed. This results were explained in terms of backdiffusion of the reaction heat throughout the structured catalysts bed, with a consequent flattening of the temperature profile, induced by the presence of the highly conductive aluminum foam carrier. The foam was able to modify the adiabatic temperature profile, obtaining, with respect to a typical packed bed reactor, a higher temperature at the inlet section and a lowered temperature at the outlet bed section, overcoming respectively, the kinetic and thermodynamic limits, achieving so an increased CO conversion. Accordingly, a conventional double staged WGS reactors with intermediate heat exchange could be replaced with a single WGS reactor characterized by a quasi isothermal adiabatic temperature profile. (C) 2016 Published by Elsevier B.V.