Catalytic Oxidation Of Dimethyl Ether Into Hydrocarbons

The Dimethyl ether (DME) Chemistry is a novel research field. The catalyticoxidation of Dimethyl ether into hydrocarbons over SnO₂/CaO, V₂O₅/SnO₂/CaO andMoO₃/SnO₂/CaO catalysts were investigated.Reverse microemulsion method was used to prepare SnO₂/CaO, V₂O₅/SnO₂/CaO andMoO₃/SnO₂/CaO catalysts. Then the prepared ctalysts were pressed, crushed andsieved to 40～60 meshes. Catalytic activities were evaluated in a continuous flowreactor made of a quartz tube (8 mm i.d.). Catalyst pellets of 40～60 mesh (0.3g) wasloaded, and a feed gas mixture of 38ï¼…DME, 8ï¼…oxygen and 54ï¼…He was introducedinto the reactor at a space velocity of 3480 ml/(g.h). The reaction was performed from150℃to 350℃under 0.1 MPa, and the effluent gas was analyzed by gaschromatographs equipped with TCD and FID detectors. The conversion of DME andthe selectivities to various products were calculated by carbon balance method.It was found that both the catalysts were active for the reaction of catalytic oxidationof dimethyl ether (DME) especially in the temperature range of 275 to 300℃.SnO₂/CaO catalyst exhibits higher activity than V₂O₅/SnO₂/CaO and MoO₃/SnO₂/CaOcatalysts. On SnO₂/CaO catalyst, DME conversion of 21.8ï¼…was attained at 300℃,while selectivities to MF(methyl formate) and DMEY(dimethoxyethane) of 19.06ï¼…and58.96ï¼…respectively were attained at 275℃.The catalysts were characterized by XRD, TGA-DTA, CO₂-TPD, Pyridine absorptionIR, and O₂-TPD. Characteristic results show: 1) perfect structure of catalysts could beattatined after calcining at 700℃for 4h; 2) For SnO₂/ CaO and V₂O₅/SnO₂/CaOcatalysts, component of SnO₂ and V₂O₅ dispersed well on the surface of the catalysts,while cubic phase of CaO dispersed in the bulk phase of the catalysts, for MoO₃/SnO₂/CaO catalysts, CaO and MoO₃ dispersed in the bulk phase of the catalysts, while ShO₂dispersed well on the surface of the catalysts; 3) the basicity is a direct proportion to theperformance of the catalysts in the reaction of catalytic oxidation of dimethyl ether tohigh hydrocarbons; 4) chemical absorbed oxygen species and basic site play importantrole in the reaction of catalytic oxidation of dimethyl ether, and promote the oxidationof dimethyl ether into hydrocarbons.