Carbon Dioxide to Chemicals: CO₂ Conversion Enhancement over Ni₃Ga/Cu-ZSM-5 Composite Material

Carbon dioxide (CO₂) is one of the major contributors toward global warming and climate change activities, and significant efforts are being taken to mitigate it in terms of reducing release, capturing, sequestering, and converting it to useful products. Among various decarbonization strategies, CO₂ hydrogenation is considered a suitable technology, but the process suffers from lower conversion, low yield, low selectivity, and cost-effectiveness issues of the catalyst employed. The literature gap lies in the inability to correlate the catalyst complexity with chemical production. The aim of this study was to synthesize an efficient and selective novel catalyst by combining two separately tested and distinct materials to create a sustainable catalyst. The constituents were chosen for their distinctive thermal and structural properties: Ni₃Ga and Cu-ZSM-5. Ni₃Ga was synthesized via facile coprecipitation, and Cu-ZSM-5 was synthesized via impregnation. The nanocomposite Ni₃Ga/Cu-ZSM-5 was synthesized by mechanochemical synthesis and was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), BET analysis, Barrett-Joyner-Halenda (BJH) analysis, transmission electron microscopy (TEM), and FTIR. Finally, it was reduced in an H₂ atmosphere at 700 °C for 2 h and tested in a thermal feed-flow reactor at different conditions. Among five different test conditions, the highest conversion and improved selectivity are observed for the Ni₃Ga/Cu-ZSM-5 sample. This enhanced efficiency can be attributed to the well-designed structural integrity of the nanocomposite and the efficient cultivation of an acidic and highly porous surface environment for the catalyst. The thermal stability of the nanocomposite can be attributed to the utilization of ZSM-5, which acts as a protective layer, lasting for a continuous stable 20 h operation production. Thus, the Ni₃Ga/Cu-ZSM-5 composite is proven to be a cheap and efficient thermal catalyst for CO₂ hydrogenation.