Efficient Ni‐based catalysts for low‐temperature reverse water‐gas shift (RWGS) reaction

Abstract

CO 2 hydrogenation for syngas can alleviate the pressure of un-controlled emissions of CO 2 and bring enormous economic benefits. Advantageous Ni-catalysts have good CO 2 hydrogenation activity and high CO selectivity merely over 700°C. Herein, we introduced Cu into Ni catalysts, which were evaluated by H 2 -TPR, XRD, BET, in-situ XPS and CO 2 -TPD, and their CO 2 hydrogenation activity and CO selectivity were significantly affected by the Ni/Cu ratios, which was rationalized by the synergistic effect of bimetallic catalysts. In addition, the reduction temperatures of studied catalysts apparently affected the CO 2 hydrogenation, which were caused by the number and dispersion of the active species. It's found that the Ni 1 Cu 1 -400 had good stability, high CO selectivity (up to 90%), and fast formation rate (1.81 × 10 À 5 mol/g cat /s) at 400°C, which demonstrated a good potential as a superior catalyst for reverse water-gas shift (RWGS) reaction.

Tuning CO2 Hydrogenation Selectivity through Reaction-Driven Restructuring on Cu–Ni Bimetal Catalysts

“…Thus, regardless of CO 2 thermodynamic stability, good adsorption makes remarkable surface basicity of the Cu 0.5 Ni 0.5 /γ-Al 2 O 3 catalyst. The increased CO 2 desorption temperature and enhanced CO 2 adsorption in the Cu 0.5 Ni 0.5 /γ-Al 2 O 3 catalyst could be possible, due to a higher percentage of Ni 0 metal compared to the other catalyst, and these observations are consistent with earlier reports …”

Boosting the performance of Ni/Al2O3 for the reverse water gas shift reaction through formation of CuNi nanoalloys

“…In the case of the bimetallic CuNi/Al 2 O 3 catalysts, reduced Ni could not be detected. This is related to the low Ni content (less than 3.5%) and the small fraction of Ni 0 in comparison with Ni 2+ species, making difficult the detection by XPS 34,87 . In addition, should be considered the effect of the passivation during the sample holding prior to measurements 71,88,89 .…”

“…Even more, carbon monoxide is preferentially adsorbed on Ni than on Cu sites 127,128 . Thus, Ni catalysts promote methanation due to the consecutive hydrogenation of carbon monoxide to methane 32,34,129 . Therefore, Cu maximizes the synergy between both metals, promoting CO desorption and supressing methane formation 24,36,130 .…”

“…This effect was attributed to the lower hydrogen adsorption capacity of Cu compared with Ni and thus, suppression of consecutive carbon monoxide hydrogenation to methane. More recently, experimental results and theoretical simulations reported that Cu-Ni catalysts have an outstanding performance compared to their monometallic counterparts, related to the formation of alloyed nanostructures [33][34][35][36][37] . However, low thermal stability and large sintering limit their application at relatively high reaction temperatures 38,39 .…”

Electrochemical control of the RWGS reaction over Ni nanoparticles deposited on yttria stabilized zirconia

“…12 Moreover, the low temperature catalytic RWGS reaction is suggested as an efficient CO 2 utilization approach in order to decrease the energy consumption and catalyst deactivation (i.e., sintering and agglomeration). 13 Among the variety of catalysts used for CO 2 hydrogenation, transition metal oxides are found to promote the RWGS reaction over the methanation reaction via a catalyst redox process, resulting in extra oxygen vacancies. [14][15][16] A recent literature review highlights the effectiveness of oxide catalysts toward the RWGS reaction in terms of their oxygen storage capacity.…”