Thermal decomposition of dimethoxymethane and dimethyl carbonate catalyzed by solid acids and bases

The thermal decomposition of dimethoxymethane (DMM) and dimethyl carbonate (DMC) on MgO, H-ZSM-5, SiO2, gamma-Al2O3 and ZnO was studied using a fixed bed isothermal reactor equipped with an online gas chromatograph. It was found that DMM was stable on MgO at temperatures up to 623 K, while it was decomposed over the acidic H-ZSM-5 with 99% conversion at 423 K. On the other hand, DMC was easily decomposed on the strong solid base and acid. The conversion of DMC was 76% on MgO at 473 K, and 98% on H-ZSM-5 at 423 K. It was even easier decomposed on the amphoteric gamma-Al2O3. Both DMM and DMC were relatively stable on SiO2 possessing little surface acidity and basicity. They were even more stable on ZnO with the conversion of DMM and DMC of about 1.5% at 573 K. Thus, metal oxides with either strong acidity or basicity are not suitable for the selective oxidation of DMM to DMC, while ZnO may be used as a component for the reaction. (C) 2005 Elsevier B.V. All rights reserved.