Highly Exposed -NH2 Edge on Fragmented g-C3N4 Framework with Integrated Molybdenum Atoms for Catalytic CO2 Cycloaddition: DFT and Techno-Economic Assessment

Abstract

This study focuses on the applicability of single-atom Mo-doped graphitic carbon nitride (GCN) nanosheets which are specifically engineered with high surface area (exfoliated GCN), -NH2 rich edges, and maximum utilization of isolated atomic Mo for propylene carbonate (PC) production through CO2 cycloaddition of propylene oxide (PO). Various operational parameters are optimized, for example, temperature (130 degrees C), pressure (20 bar), catalyst (Mo(2)GCN), and catalyst mass (0.1 g). Under optimal conditions, 2% Mo-doped GCN (Mo(2)GCN) has the highest catalytic performance, especially the turnover frequency (TOF) obtained, 36.4 h(-1) is higher than most reported studies. DFT simulations prove the catalytic performance of Mo(2)GCN significantly decreases the activation energy barrier for PO ring-opening from 50-60 to 4.903 kcal mol(-1). Coexistence of Lewis acid/base group improves the CO2 cycloaddition performance by the formation of coordination bond between electron-deficient Mo atom with O atom of PO, while -NH2 surface group disrupts the stability of CO2 bond by donating electrons into its low-level empty orbital. Steady-state process simulation of the industrial-scale consumes 4.4 ton h(-1) of CO2 with PC production of 10.2 ton h(-1). Techno-economic assessment profit from Mo(2)GCN is estimated to be 60.39 million USD year(-1) at a catalyst loss rate of 0.01 wt% h(-1).