Catalysis Letters, Vol.126, No.3-4, 308-312, 2008
Acid Strength of H3PW (x) Mo12-x O-40 and H6P2W (x) Mo18-x O-62 Heteropolyacid Catalysts as a Probe of Acid Catalysis for 2-Propanol Conversion Reaction
Acid strength of H3PW (x) Mo12-x O-40 (x = 0, 3, 6, 9, and 12) Keggin heteropolyacid (HPA) and H6P2W (x) Mo18-x O-62 (x = 0, 3, 9, 15, and 18) Wells-Dawson HPA catalysts was determined by NH3-TPD measurements. Desorption peak temperature (acid strength) of H3PW (x) Mo12-x O-40 and H6P2W (x) Mo18-x O-62 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 H3PW (x) Mo12-x O-40 and H6P2W (x) Mo18-x O-62 catalysts could be utilized as a probe of acid catalysis for 2-propanol conversion reaction.