Excellent performance of TiO2(B) nanotubes in selective transesterification of DMC with phenol derivatives

• TiO2(B) showed higher activity in transesterification of DMC with phenol derivatives.
• TG–MS and DRIFTS characterized DMC desorption, adsorption and activation mechanism.
• TiO2(B) nanotubes has higher Ti3+ content than anatase TiO2.
• Activity was related with higher Ti3+ content, surface area and structure defects.

TiO2(B) nanotubes and anatase TiO2 were synthesized, and the transesterification of dimethyl carbonate (DMC) with phenol and its derivative bisphenol A (BPA) were carried out over them. When reaction was carried out over TiO2(B) nanotube at 150 °C, phenol conversion obtained 7.8% and transesterification selectivity reached 99.8%. As reaction temperature increased to 170 °C, phenol conversion came up to 54.6% and transesterification selectivity can still maintain a good yield at 99.2%. When bulk BPA reacted with DMC at 150 °C, transesterification selectivity and BPA conversion reduced to 92.4% and 3.9%. Raising temperature to 170 °C, BPA conversion increased to 43.4%, but transesterification selectivity declined to 90.3%. However, the transesterification of DMC with phenol and BPA took place at 150 °C over anatase TiO2, the transesterification selectivity significantly declined to 92.7% and 76.1%, and phenol and BPA conversion only achieved 5.1% and 3.0%. The higher activity of TiO2(B) nanotubes in transesterification was due to its larger surface area, higher pore size and more structure defects. Importantly, in situ DRIFT and TG–MS were used to characterize DMC adsorption, activation and decomposition process over TiO2(B) surface, which provided more information about the mechanism of transesterification and methylation.

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