Rich -NH2 Mesoporous g-C3N4 Nanosheets Efficient for Cycloaddition of CO2 to Epoxides without Solvent and Co-Catalyst

摘要

Graphitic carbon nitride (g-C3N4) with N-containing groups is an attractive catalyst for various CO2-activating reactions. Herein, a rich -NH2 mesoporous g-C3N4 nanosheets catalyst was successfully prepared by thermal exfoliation from bulk g-C3N4 with porous structure using urea and melamine as precursors. With urea as precursor and bubble template, the nanosheets after thermal exfoliation showed large surface area (236.4 m(2) g(-1)), rich mesopores and -NH2 groups, which are base sites of cycloaddition of CO2 to epoxides. The obtained catalyst showed high catalytic performance for CO2 cycloaddition without solvent and co-catalyst. Propylene oxide (PO) and CO2 cycloaddition to propylene carbonate (PC) was used as probe reaction to evaluate the catalytic performance. Under the optimal reaction conditions (130 degrees C, 2.5 MPa, 20 h), the conversion of PO was 97.8 % and selectivity to PC was 98.1 %. In addition, the obtained catalyst showed good suitability for various substrates in CO2 cycloaddition and stability.