Influence of Nickel Loading on Reduced Graphene Oxide-Based Nickel Catalysts for the Hydrogenation of Carbon Dioxide to Methane

Nur Diyan Mohd Ridzuan,Israf Ud Din,Maizatul Shima Shaharun,Kah Mun Lee,Poppy Puspitasari

doi:10.3390/catal10050471

Abstract

In this study, a series of novel nickel catalysts supported on reduced graphene oxide nanosheets (Ni/rGO) with Ni loadings of 10, 15 and 20 wt% were successfully synthesized via the incipient wetness impregnation method. The physicochemical properties of the catalysts and rGO support were thoroughly characterized by thermogravimetric analyser, X-ray diffraction, fourier-transform infrared spectroscopy, Raman spectroscopy, N2 adsorption-desorption, temperature programmed reduction, temperature programmed CO2 desorption and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. The properties of the catalysts are correlated to its catalytic activity for CO2 methanation which were investigated using three-phase slurry reactor at low temperature and pressure of 240 °C and 10 bar, respectively. Among the three catalysts of different Ni loading, Ni15/rGO shows the highest activity of 51% conversion of CO2 with total selectivity towards CH4. N2-physisorption and CO2-TPD analysis suggest that high catalytic performance of Ni15/rGO is attributed to the high surface area, strong basic sites and special support effect of rGO in anchoring the active metal.

Highlights

The concentration of carbon dioxide (CO2 ), a major component of greenhouse gases, is rapidly increasing in the atmosphere [1]
The Thermogravimetric analysis (TGA) profile of reduced graphene oxide (rGO) implies that rGO has excellent thermal stability because heating up to 900 ◦ C only resulted in a 15.14% weight loss
The presence of physisorbed water on the rGO surface is due to the porous characteristics and oxygen functional groups on the edge of graphene [20,25,26]

Summary

Introduction

The concentration of carbon dioxide (CO2 ), a major component of greenhouse gases, is rapidly increasing in the atmosphere [1]. With over 30 gigaton (Gt) emissions a year, high atmospheric CO2 is alarming as it will create critical risks for the Earth’s climate system [2]. Due to the global concern about the climate change, CO2 conversion into valuable low-carbon fuels such as methane (CH4 ) is seen as a viable solution to reduce anthropogenic CO2 emissions [3]. CO2 methanation, as in Equation (1), was initially reported by Sabatier and Senderens in 1902 [4]. Technology, CH4 will be produced from Sabatier reaction by reacting CO2 recovered from industrial process with hydrogen (H2 ) from water splitting.

Methods

Results

Conclusion