Methanol carboxylation over zirconium dioxide

What is it about?

Varying the calcination temperature causes the change of ZrO2 phase composition, as well as acid-base characteristics. The base properties of ZrO2 play a prominent role in the dimethyl carbonate synthesis. The presence of strong base sites is needed to activate СО2. Tetragonal modification of zirconium dioxide has a higher basicity than the monoclinic. Thus, the greater is the contribution of t-ZrO2 in the catalyst, the greater is its ability to activate СО2, and therefore − higher catalytic activity towards methanol carboxylation. DMC selectivity has been determined by the ratio of catalyst base and acid sites concentration.

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Why is it important?

Calcination temperature effects on ZrO2 phase composition and acid-base properties. t-ZrO2 is characterized of higher basicity as compared with m-ZrO2. Sufficiently strong base sites are needed to activate the inert molecule of СО2. The absence or small strength of base sites causes solely the methanol transformations. The contribution of t-ZrO2 promotes the catalytic activity in methanol carboxylation.