Ceria coated microchannel reactor for water-gas shift reaction

In this study, it is aimed to develop a method for coating Pt/CeO2/Al2O3 catalyst onto the FeCrAlY-based wall of a microchannel reactor and to study watergas shift (WGS) in the context of a parametric study. Firstly, the development of catalyst coating method is examined. The biggest concern about coating was the instability of the coated layer, which came from the presence of CeO2. Therefore, it is decided to use polyvinyl alcohol (PVA) as a binder between the metal surface and the catalyst. After a number of trials including the optimization of the amount of PVA, drying and calcination programs and the way of coupling PVA and the catalyst, a procedure that allowed stable coating of the catalyst was developed. The second part of the study involved investigation of the effect of reaction temperature (300, 325 and 350 ◦C) and molar inlet steam-to-carbon ratio (S/C=2 and 3) on CO conversion in the catalyst coated microchannel reactor. It was observed that conversions notably increased with the temperature, but responded slightly upon changing S/C. The highest CO conversion of 12.96 was achieved at 350 ◦C and S/C=2. Additionally, the effect of different amounts of catalyst loadings on FeCrAlY plates was examined. The results revealed that 6 and 12 mg coatings do not show the same level of difference in terms of CO conversion. Interestingly, 9 mg catalyst coating gave conversions slightly lower than those of 6 and 12 mg coatings. Finally, the effect of the different microchannel reactor configurations, coated and packed microchannels, was explored under identical residence times, defined as the ratio of catalyst weight to the total volumetric inlet flow rate. It was observed that, in general, coated configuration gave slightly higher conversions than the packed one, possibly due to better heat distribution and catalyst utilization in the former.