"Catalytic vs Electrocatalytic reduction of CO2 to valuable products"

"Catalytic vs Electrocatalytic reduction of CO2 to valuable products" In recent times there has been a great increase in carbon dioxide emissions caused by technological development and the continuous use of fossil fuels. For this reason the scientific community has focused on different possibilities for CO2 reduction. One of the possible routes is represented by the use of CO2 as a reagent to obtain high value-added products such as methanol. Methanol represents a feedstock of many chemicals processes for the production of chemicals and it is a green fuel with an energy density comparable to the mostly used fuel, such as gasoline (methanol: 15.6 MJ L-1; gasoline: 34.2 MJ L-1). According to the literature there are several routes to produce methanol from CO2; in this work we analyse two different ones: thermocatalytic and electrocatalytic reduction. Indeed the molecule of CO2 is very stable and the reactions to produce methanol need a high energy quantity to occur. Therefore the CO2 hydrogenation reaction depends on the development of an effective catalyst. Usually, the methanol is produced by reducing CO by using a catalyst consisting of copper oxide, zinc oxide and aluminum oxide (CuO/ZnO/Al2O3). For that reason, in this study ternary CuO/ZnO/Al2O3 (CZA) catalyst was prepared via the coprecipitation route using a solution of nitrates [(Cu(NO3)2 (0.6 mol L-1 ), Zn(NO3) 2 (0.3 mol L-1 ), Al(NO3)3 (0.1 mol L-1 )] and a solution of sodium carbonate [(Na2CO3) (1 mol/L)] as a precipitant under strict control of parameters such as pH (7), precipitation temperature (70°C), and calcination temperature (350°C) according to the literature. Besides, binary CuO/ZnO (CZ) catalyst was synthesized in the same conditions and both were compared with the commercial catalyst (CC) used in reducing CO towards methanol and purchased from the “Alfa Aesar”. The three catalysts have been characterized using XRD, FESEM, EDX, H2-TPR, BET, CV, LSV and CA techniques and tested both thermochemically and electrochemically. About the thermochemical route, a process simulation was also carried out using the software aspen V8.8. First of all, the thermodynamic equilibrium was studied and subsequently a reaction kinetics concerning the CZA catalyst and found in the literature was introduced.