Acid Strength of H3PW x Mo12−x O40 and H6P2W x Mo18−x O62 Heteropolyacid Catalysts as a Probe of Acid Catalysis for 2-Propanol Conversion Reaction

Acid strength of H3PWxMo12−xO40 (x = 0, 3, 6, 9, and 12) Keggin heteropolyacid (HPA) and H6P2WxMo18−xO62 (x = 0, 3, 9, 15, and 18) Wells-Dawson HPA catalysts was determined by NH3-TPD measurements. Desorption peak temperature (acid strength) of H3PWxMo12−xO40 and H6P2WxMo18−xO62 catalysts showed the same trend with respect to tungsten substitution, and increased with increasing tungsten substitution in both families of HPA catalysts. In order to correlate the acid strength with the acid catalysis of HPAs, vapor-phase 2-propanol conversion reaction was carried out as a model reaction. Yield for propylene (a product formed by acid catalysis of HPA) increased with increasing tungsten substitution and with increasing desorption peak temperature (acid strength) across both HPA families, regardless of the identity of HPA catalyst (without HPA structural sensitivity). The acid strength of H3PWxMo12−xO40 and H6P2WxMo18−xO62 catalysts could be utilized as a probe of acid catalysis for 2-propanol conversion reaction.