Gas-phase synthesis of dimethyl carbonate from methanol and carbon dioxide over Co(1.5)PW(12)O(40) Keggin-type heteropolyanion.

The reactivity of Co(1.5)PW(12)O(40) in the direct synthesis of dimethyl carbonate (DMC) from CO(2) and CH(3)OH was investigated. The synthesized catalyst has been characterized by means of FTIR, XRD, TG, and DTA and tested in gas phase under atmospheric pressure. The effects of the reaction temperature, time on stream, and methanol weight hourly space velocity (MWHSV) on the conversion and DMC selectivity were investigated. The highest conversion (7.6%) and highest DMC selectivity (86.5%) were obtained at the lowest temperature used (200 degrees C). Increasing the space velocity MWHSV increased the selectivity of DMC, but decreased the conversion. A gain of 18.4% of DMC selectivity was obtained when the MWHSV was increased from 0.65 h(-1) to 3.2 h(-1).