Isotope effect in formaldehyde steam reforming on Pt/m-ZrO2: Insight into chemical promotion by alkalis
Infrared spectroscopy, temperature programmed reaction mass spectrometry (TP-reaction/MS), and catalyst testing were used to investigate alkali promotion of dehydrogenation selectivity during formaldehyde steam reforming (FSR) on Pt/m-ZrO2. In a preferred pathway, formaldehyde reacts with water forming hydrogen and formate, followed by forward formate decomposition to CO2 and H2. Alkali-doping of 2 wt% Pt/m-ZrO2 increases catalyst basicity, which weakens the formate C-H bond promoting formate dehydrogenation / decarboxylation. Promotion by alkali in FSR was observed through a formate ν(CH) band shift to lower wavenumbers in infrared spectroscopy, and through a decrease in the normal isotope effect in switching from H- to D-labeled formaldehyde in TP-reaction/MS.