CO₂ conversion over Cu–Mo₂C catalysts: effect of the Cu promoter and preparation method

Abstract

Strong interaction between the Cu and Mo2C phases and formation of Mo2C–Cu+ interfaces is required for the efficient hydrogenation of CO2 to methanol.

Recent Advances in Carbon Dioxide Adsorption, Activation and Hydrogenation to Methanol using Transition Metal Carbides

“…[173] In 2021, Heracleous et al synthesized the catalyst with 20 wt % CuÀ Mo 2 C via the sol-gel (SG) auto-combustion route (or CuÀ Mo 2 CÀ SG) and compared its activity (in terms of both CO 2 conversion rate and methanol selectivity) with the same catalysts prepared by using the solvothermal and solid-state methods. [174] The catalyst prepared via the sol-gel autocombustion method exhibited a CO 2 conversion rate of around 30 mol % at 325 °C and 45 bar with the highest selectivity to methanol of around 50 C-mol % at 5 mol % conversion. Catalyst performance dropped approximately 30-40 % for the CuÀ Mo 2 C, which was prepared by the solvothermal (SV) method, whereas the CuÀ Mo 2 C catalyst prepared by the solid-state (SS) (CuÀ Mo 2 C) method showed no catalytic activity.…”

“…Thus, it covers a large part of the active sites. [175] Rodriguez et al, [176] Zhang et al, [123] and Dubois et al [42] observed a slight decrease in the total conversion of CO 2 after increasing the Cu loading on Mo 2 C. In contrast, Chen et al, [177] Xiong et al, [142] and Heracleous et al [174] observed the increase in the rate of CO 2 hydrogenation on loading Cu to carbides. These discrepancies originate due to different Cu loading and catalyst preparation methods and experimental conditions.…”

“…Further, Heracleous et al claimed that Cu loading has a positive effect on methanol selectivity compared to pure β-Mo 2 C in the temperature range 200-250 °C. [174] In 2020, Zhu et al prepared a class of passivated and nonpassivated molybdenum (oxy)carbide catalysts using activated carbon as support via the carbothermal hydrogen reduction method. [39] The Mo/C precursor was prepared by the impregnation method and carburized at selected temperature of 500, 600, 700, and 800 °C for 6 h. These catalyst were denoted as Mo/C(T) [i. e., Mo/C(500), Mo/C(600), Mo/C(700), and Mo/C(800)], where T stands for the carburization temperature.…”

“…In 2021, Heracleous et al. synthesized the catalyst with 20 wt % Cu−Mo 2 C via the sol‐gel (SG) auto‐combustion route (or Cu−Mo 2 C−SG) and compared its activity (in terms of both CO 2 conversion rate and methanol selectivity) with the same catalysts prepared by using the solvothermal and solid‐state methods [174] . The catalyst prepared via the sol‐gel auto‐combustion method exhibited a CO 2 conversion rate of around 30 mol % at 325 °C and 45 bar with the highest selectivity to methanol of around 50 C‐mol % at 5 mol % conversion.…”

Mesoporous Cu Catalysts for Dimethyl Oxalate Selective Hydrogenation: Impact of the Cu/Al interface on the Textural Properties and Catalytic Behavior

“…Particularly, the Cu 2p XPS spectra of the monometallic Cu catalyst (Figure 7(b)) shows that two well resolved peaks centered at 952.4 eV and 932.7 eV, corresponding to Cu + 2p1/2 and Cu 0 2p3/2 transitions. [36] Perhaps, the Cu/OH interface in the monometallic Cu catalyst should be the main reason for creating the active Cu + sites. Compared to the monometallic Cu catalyst, the Cu 2p3/2 peak of the CuAl(O) catalyst shifted to the low binding energies of 930.2 eV.…”