Study On Deactivation Of Cu^I/S₂O₈^2-/γ-Al₂O₃ Catalyst For Dimethyl Carbonate Synthesis

Dimethyl carbonate(DMC) is an environmental-friendly innocuity green chemistr and be used in the reaction of carbonylation, methylation and methoxylation. The synthesis route of methanol oxidative carbonylation to DMC used CH3OH, CO and O2 as materials, is very advantageous in thermodynamics and mature in technics and cheap materials as well. It is in according with the concept of 21th century green chemistry and become one of research focused on currently.It has been proved that the industrialized catalyst CuCl possesses the innate defect of polluting production and serious causticity to equipment. Early research indicated that the low chloride catalysts CuI/SO42-/MxOy and CuI/S2O82-/MxOy were prepared by the solid ion exchange with Br?nsted acid sites lies on SO42-/MxOy and S2O82-/MxOy super acid and CuCl, and the catalysts were active in oxidative carbonylation of methanol to dimethyl carbonate (DMC).The paper investigated the stability and the deactivation reason on the best active catalyst CuI/S2O82-/γ-Al2O3.The fresh and recycle catalysts were characteristed by the elemental analysis, XRD, DTG, Py-FTIR, FTIR, NH3-TPD etc.Early research indicated that H2O which existed in the slurry reactor had toxic and side-effect on the Cu catalyst. The paper studied that the amount of H2O had influence on the catalyst deactivation in oxidative carbonylation of methanol to dimethyl carbonate (DMC). The fresh and recycle catalysts were characteristed by the elemental analysis, XRD, DTG, Py-FTIR, FTIR, NH3-TPD etc.The conclusions shows as below:(1) The losting of Cu element led the catalyst deactive rapidly by the characteristics of the elemental analysis. Catalyst used once lost more than 50% Cu element compared with the fresh one.(2) The CuI loaded on Br?nsted acid sites on super acid was instability by the characteristics of NH3-TPD,FTIR and Py-FTIR, which lost easily in the reaction, it accelerated the losting rate of Cu element.(3) The CuCl crystal that detected in the fresh catalyst disappeard and the inactive substance Cu2(OH)3Cl were founded in the used catalyst by the characteristics of XRD and DTG. Cu2(OH)3Cl is formed from Cu element and by-produce H2O, which lead the catalyst deactivation.(4) With the amount of H2O increasing, the losting rate of Cu element accelerated and the crystal of Cu2(OH)3Cl enhanced, which led the catalyst deactived rapidly.