Study On CeO₂and Ce_1-xLa_xO Catalysts For Direct Synthesis Of Dimethyl Carbonate From Carbon Dioxide And Methanol

Dimethyl carbonate (DMC) is an important green chemical product and is knownas the "new cornerstone" of organic synthesis. The synthesis route of DMC from CO2and methanol follows the principle of green chemistry. Besides, the utilization of CO2can relieve the greenhouse effect and reduce air pollution. Above all, this process is ofhighly development potential. CeO2catalyst is reported to be of high activity. In ourwork, we mainly investigated CeO2crystals with different morphologies andCe1-xLaxO catalysts for the direct synthesis of DMC, as discussed in followingaspects:CeO2catalysts with morphologies of nano-octahedrons, naorods, nanocubes andspindle-like structures were synthesized successfully. The crystal properties, texturalproperties and acid-base properties of CeO2catalysts with various morphologiesanalyzed and catalytic tests of these samples were conducted to correlate with theircatalytic performances. Our research results indicated that a synergism among theexposed (111) plane, defect sites and acid-basic sites was proposed to be crucial toobtaining the high reactivity of DMC formation.Modified CeO2catalysts via the addition of certain metal ions(Mg、Zn、Al、La)in the form of solid solution to change the acid-base properties of ceria catalysts. Ourresults indicated that CeLaO catalysts with La as doping ions possessed the highestDMC yields. Then, we synthesized a serious of Ce1-xLaxO catalysts with differentratio of Ce/La to explore the correlation of properties and activities for DMCformation. Our experimental results indicated that the Ce0.95La0.05O catalyst withmolar ratio of La/La+Ce0.05exhibited the best DMC yield because of their weakacid-base sites and large amount of moderate acid-base sites.