Catalytic Reactivity of 12-Molybdophosphoric Acid and its Copper and Zinc Salts in CO2 Methanol Reforming

Abstract

The CO₂ methanol reforming reaction over Keggin type heteropoly compounds catalysts was investigated. The catalysts prepared, H₃PMo₁₂O₄₀ and its salts Cu_1.5PMo₁₂O₄₀ and Zn_1.5PMo₁₂O₄₀ were characterized by means of IR, XRD and TG. Catalytic tests were carried out under atmospheric pressure at 573 K in a continuous flow system using a glass reactor. The results obtained showed that the unsupported H₃PMo₁₂O₄₀ is more active than its copper and zinc salts. As for the alumina-supported H₃PMo₁₂O₄₀, it has been observed that, besides methyl formate (MF), formaldehyde (HCHO) and dimethyl ether (DME), the dimethyl carbonate (DMC) was obtained. The formation of the latter, observed only on the supported catalysts, seems to indicate that its formation requires both, Lewis-acid and redox sites. Bronsted-sites reduce its formation in favour of dimethyl ether (DME) and strong redox sites in favour to formaldehyde (HCHO).