CO2 Utilization: Converting Waste into Valuable Products

Abstract

Carbon dioxide capture, utilization, and storage (CCUS), which includes conversion to valuable products, is a complex modern issue with many perspectives. In recent years, the idea of using carbon dioxide (CO2) as a feedstock for synthetic applications in the chemical and fuel sectors via reduction reactions has piqued interest. If the hydrogen is created using a renewable energy source, catalytic CO2 hydrogenation is the most viable and appealing alternative among the existing CO2-recycling solutions. CO2 hydrogenation has many chemical paths depending on the catalyst, and multiple value-added hydrocarbons can be generated. This research looks into a catalyst development for converting high CO2 gas field into methane and alcohols. The study focused on catalytic conversion of CO2 to methane over Ru based catalyst while in the case of alcohols using Cu based catalyst. Both catalysts were synthesized via impregnation techniques where the aqueous precursors’ solution were impregnated on the oxide supports, stirred, filtered and washed. The samples were then dried, ground and calcined. The synthesized catalysts were characterized using various analytical techniques (e.g., TPR, FESEM, N2 adsorption-desorption, XRD) for their physicochemical properties. The catalytic performance in CO2 hydrogenation was performed using a fixed bed reactor at various factors such as temperature, pressure, feed gas ratio and space velocity. The experimental findings indicate that conversion of CO2 to methane over Ru based catalyst resulted in >84% CO2 conversion with 99% methane selectivity in the range of temperature 280 – 320 °C and at atmospheric pressure. In the case of hydrogenation of CO2 to alcohols, the catalytic performance of Cu based catalyst exhibited CO2 conversion of >11% and selectivity towards alcohols, C1 and C2, both at 4% with reaction temperature of 250 °C and pressure 30 bar. These findings revealed that methane could easily be formed from CO2 as compared to alcohol. However, both technology conversions are dependent on the catalyst selection and its’ activity. Process parameters need to be optimized to maximize targeted product formation and suppress the side products.