Synthesis of Propylene Carbonate from CO2 Catalyzed by Metal-free Carbon Nitride
The exfoliated graphitic carbon nitride(eg-C3N4)material was synthesized by thermal polymerization and thermal exfoliation using dicyanodiamide as a precursor,and the eg-C3N4-S materials were prepared by treatment of H2SO4.The physicochemical properties,including porous structure,chemical compositions etc.,of the materials were characterized by N2 adsorption-desorption,XRD,FT-IR,XPS and UV-Vis spectroscopy.The characterization results showed that exfoliation effectively increased the specific surface area of g-C3N4,while H2SO4 treatment introduced hydroxyl group.In the catalytic reaction of cycloaddition of CO2 with propylene oxide to propylene carbonate,eg-C3N4-S showed higher catalytic activity than g-C3N4 without H2SO4 treatment or thermal exfoliation.Under the reaction pressure of 2.0 MPa and temperature of 140℃,the propylene oxide conversion and propylene carbonate selectivity were 85%and 98%,respectively.
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