Glycerol-assisted dynamic hydrothermal synthesis of nickel phyllosilicate for enhanced CO2 methanation: Synergistic effect of stirring and viscous solvent

Abstract

To address the shortcomings of poor convection and product agglomeration of the static hydrothermal method, the dynamic hydrothermal method together with the viscous solvent-assisted dynamic hydrothermal method were proposed to synthesize Ni-phyllosilicate in this work. Stirring seemed to be powerful to accelerate the synthesis with significant increase of Ni content from 11.80 wt% (static synthesis) to 23.13 wt% (dynamic synthesis). The further modification of glycerol increased the shearing force to exfoliate the Ni-phyllosilicate nanosheets during dynamic synthesis, whose thickness could reach 1.17 nm with improved metal utilization ratio after reduction. As a result, the activity of CO2 methanation was enhanced with large TOFCO2 of 3.5 × 10−2 s−1 and small Ea of 65.13 kJ·mol−1. In situ DRIFTS analysis confirmed the existence of high actively intermediate of m-HCOO− and *CO, which could be further hydrogenated into CHx species. In short, the synergistic effect of dynamic stirring and glycerol modification drove the enhancement of catalytic activity, and also provided the possibility of large-scale production of Ni-phyllosilicate using hydrothermal method.