Fabrication of solid strong bases at decreased temperature by doping low-valence Cr³⁺ into supports

Mesoporous solid strong bases (MSSBs) have gained tremendous research interest as environment-friendly catalysts in various reactions. Nevertheless, the fabrication of MSSBs remains an enormous challenge because a pretty high temperature is needed to produce strong basicity in traditional mesoporous materials. Here, we report a strategy of endowing supports with reducibility (ESWR) by doping low-valence Cr³⁺ into mesoporous Al₂O₃. The base precursors NaNO₃ can be converted to basic sites completely at the low temperature of 400 °C via the ESWR strategy. The examination of activation mechanism indicates that the redox interaction between Cr³⁺ and NaNO₃ is responsible for the low-temperature conversion of supported NaNO₃. As a result, MSSBs were synthesized successfully by the ESWR strategy, showing strong basicity and remarkable catalytic activity in the transesterification reaction. The catalytic activity is obviously higher than typical solid bases like MgO as well as a variety of reported basic catalysts.