Transformation of CO2 into value-added green hydrocarbon components through a modified catalytic route using biomass-generated graphene-based structures

Abstract

Carbon dioxide gas is considered one of the major contributors to the global warming phenomena and acid rains which have serious impacts on both the environment and living creatures. However, carbon dioxide can be of high benefit if introduced in some chemical processes to produce valuable products. In agreement with this goal, this research study presents the catalytic conversion of CO2 gas to hydrocarbon structures that can be highly advantageous in the energy sector. Three novel catalysts made of graphene as a support layer and active sites of transition metals (Ni, Cu, and Zn) nanoparticles were utilized during the conversion process. The preparation of these catalysts launched by producing graphene from rice straw through thermochemical treatment followed by the direct loading of metals nanoparticles on an individual basis. The structural and surface characteristics of the prepared catalytic structures were determined via Fourier Transform Infrared (FTIR), Raman Spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N2 adsorption–desorption surface area analysis. The catalytic performances of these three structures toward the conversion of carbon dioxide into valuable hydrocarbons were then investigated at different operating temperatures and reaction residence time (as a modified pathway imitating the Fischer–Tropsch reaction). The three structures could show significant activity in terms of attaining high levels of CO2 conversions which were detected as approximately 99, 95, and 82% for Ni, Zn, and Cu-containing catalysts respectively. Nevertheless, the catalysts which were made of Ni and Cu nanoparticles revealed high selectivity (nearly 55%) toward the production of liquefied petroleum gas (LPG) fractions while Zn-based catalysts could display a complete tendency to reduce carbon dioxide into CO. On the other hand, Ni-catalysts could also exhibit increased selectivity to produce the components of natural gas (NG) fraction.