Study of CO oxidation activity of NiO-PDC and NiO-YSZ catalysts coated on alumina wash-coated honeycomb cordierite monolith

Abstract

In this study, the EDTA-Citrate method was employed to synthesize NiO-PDC (NPC) and NiO-YSZ (NYZ) powder catalysts in nanostructured form. Subsequently, the catalysts were slurry dip-coated onto monolith cordierite substrates with alumina, using a one-step coating approach, and their CO oxidation activity was tested. The coating was achieved by first mixing the catalyst with the alumina suspension to prepare a homogeneous slurry, which was then used for dip coating onto the monolith. The adherence test was performed on the coated monolith to evaluate the mechanical stability of the catalyst-alumina composite layer. The coating was visually confirmed through optical imaging. The remaining powders (after coating) were then subjected to BET surface area, XRD, Raman spectroscopy, H<inf>2</inf> TPR and O<inf>2</inf> TPD analysis for characterization. Raman spectra showed that NPC exhibited higher oxygen vacancies than NYZ. H<inf>2</inf> TPR and O<inf>2</inf> TPD provided better evidence of the reduction potential and O<inf>2</inf> desorption of NPC respectively. NPC/cord demonstrated the highest catalytic activity (T<inf>50</inf> = 165 °C) compared to NYZ/cord (T<inf>50</inf> = 215 °C) and bare cordierite (T<inf>50</inf> = 777 °C), which is attributed to its better redox properties and higher oxygen vacancies. The effect of flow rate and heating rate on CO oxidation was studied on NPC/cord and NYZ/cord. The long-term stability of the NPC/cord and NYZ/cord were tested through 5-h and 50-h isothermal studies. © The Author(s) under exclusive licence to Associação Brasileira de Engenharia Química 2025.