Study On The Preparation Of ZrO₂-SiO₂in Ionic Liquids And Its Catalytic Performance For Synthesis Of Methyl Phenyl Carbamate

Methyl N-phenyl carbamate （MPC） is the important intermediate product for thesysnthesis of4,4`-diphenylmethane diisocyanate （MDI） via dimethyl carbonate （DMC）route. In this paper, nano ZrO₂and composite oxides ZrO₂-SiO₂were prepared throuthsol-gel process. And the effect of ionic liquid template agent was also investigated. Thecatalytic performance of the obtained ZrO₂and ZrO₂-SiO₂were evaluted by the synthesis ofMPC from aniline and DMC.By the sol-gel process prepared for nano-sized ZrO₂and characterization as a mixtureof monoclinic and tetragonal likes coral-like particle morphology. Adding into the ionicliquid of [bmim]BF4or [bmim]Br, its obtained ZrO₂were pure monoclinic phase and puretetragonal phase. The former is about50nm thick, about1μm flat hexagonal flakyparticles, the latter is reunion body consisting of particle size of50nm spherical smallparticles. We used ZrO₂for the synthesis of methyl N-phenyl carbamate reaction catalyzedby aniline and dimethyl carbonate.[Bmim]Br-H2O preparation of ZrO₂, its catalyticperformance was the best. Aniline conversion rate is36.7%, the MPC selectivity is42.9%.This is due to its surface has a large number of acid centers.By the sol-gel process prepared for composite oxides ZrO₂-SiO₂.finds the siliconoxide’s adding infuenced zirconia’s nucleation and growth process. XRD patterns of sol-gelmethod and the preparation of composite oxide ZrO₂-SiO₂in [bmim]Br-H2O solution. Itonly corresponds to the amorphous material diffraction peak. In the [bmim]BF4-H2Osolution, the preparation of ZrO₂-SiO₂XRD patterns appeared in the diffraction peaksattributed to tetragonal ZrO₂. It was used for the synthesis of methyl N-phenylcarbamate（MPC） from aniline and dimethyl carbonate（DMC）.[Bmim]Br-H2O preparationof ZrO₂-SiO₂, its catalytic performance was the best. Aniline conversion rate is75.0%,theMPC selectivity is43.3%. Although the catalytic activity among [bmim]Br-ZrO₂,sol-gel-ZrO₂-SiO₂and [bmim]Br-ZrO₂-SiO₂are different. The MPC selectivity is veryclosely. It demonstrates that the surface acid center nature is similar; the differences are in the quantity.