Synthesis Of Dimethyl Carbonate From Urea And Methanol Over Fe₂O₃/HMCM-49 Or Complexes With Iron

In this paper, load type catalyst Fe2O3/HMCM-49 and urea complexes with iron(ш), which were simple, nontoxic and safe, were prepared by impregnation method and solid state synthesis. Many characterizations of catalyst were tested by XRD, TEM, NH3-TPD, FT-IR, BET, and ICP-MS.In the batch process, Fe2O3/HMCM-49 exhibited high activity for producing dimethyl carbonate (DMC) from methanol and urea. By studing on the preparation conditions for producing Fe2O3/HMCM-49 and DMC, the optimal concentration of Fe(NO3)3 solution in ethanol for preparing catalyst with higher activity was 0.2mol/L and calcined at 500℃.And the optimal preparation conditions for producing DMC from methanol and urea using Fe2O3/HMCM-49 are as follows:the CH3OH/urea molar ratio 160:1, the reaction temperature 180℃, the reaction time 8 h, amount of the catalyst 0.3 g, and the stirring speed 500 rpm.34.2% conversion and 97.6% selectivity of DMC are achieved under the optimal conditions. Otherwise, the catalytic activity of the reused catalyst, DMC yield and selectivity were almost not affected even at the third run.Urea complexes with iron(ш) was prepared by solid state synthesis, and some characterizations of catalyst were tested. Research showed that the complexes were formed by Fe and oxygen of urea forming the coordination. Fe2O3/HMCM-49 exhibited high activity for producing DMC from methanol and urea.The activity of the complexes for producing DMC from methanol and urea was discussesed. And the optimal preparation conditions:the CH3OH/urea molar ratio 100:1, the reaction temperature 170℃, the reaction time 8 h, amount of the catalyst 0.5 g. and the stirring speed 500 rpm.10.2% yield of DMC are achieved under the optimal conditions.The role features of catalyst for producing DMC from methanol and urea with urea complexes with iron(ш) was got.Besides. on the basis of the previous report in literatures and the experimental results obtained in this case the mechanism of the svnthesis reaction with Fe2O3/HMCM-49 via the mutual activation of urea by Fe [O] and H+ was proposed. And the reason why selectivity of DMC reached very high were explained in this mechanism.