Carbon nanofiber-based copper/zirconia catalyst for hydrogenation of CO2 to methanol

•Novel CNFs based Cu/ZrO2 catalyst with variant zirconia concentration was investigated for CO2 hydrogenation to methanol.•ZrO2 promotion increased number of basic sites, consequently CO2 conversion was improved.•The 15 wt% was found an optimum zirconia concentrations for the title reaction.•Efficient CO2 conversion at relatively low reaction temperature.

This article describes the synthesis of methanol by the direct hydrogenation of CO2 over Cu/ZrO2 catalyst at different ZrO2 concentrations (5, 10, 15, 20 and 25 wt.%) in a three-phase phase reactor. The techniques of N2 adsorption/desorption, x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, temperature-programmed desorption by CO2, N2O chemisorption and inductively coupled plasma optical emission spectrometry were employed for catalyst characterization. At a reaction temperature of 180 °C, pressure of 3.0 MP and 0.020 g/mL of the catalyst, the conversion of CO2 and the yield of methanol were 10% and 25 g/kg.h, respectively. Surface area of the metallic copper was increased from 8.1 to 9.5 m2/g with the presence of ZrO2 from 5 to 15 wt.%. The methanol turnover frequency exhibited a linear relationship with ZrO2 concentration. Methanol synthesis rate was progressively increased with increasing fraction of dispersed copper. A comparative study with the literature revealed better activity of this novel catalyst at relatively low reaction conditions.