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

• Published in: Catalysis science & technology Vol. 12; no. 2; pp. 474 - 487
• Main Authors: Gioria, Esteban, Ingale, Piyush, Pohl, Felix, Naumann d'Alnoncourt, Raoul, Thomas, Arne, Rosowski, Frank
• Format: Journal Article
• Published: 26.01.2022
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/d1cy01585k

Ni supported on alumina is extensively employed as a catalyst for the reverse water gas shift reaction. However, the formation of inactive Ni aluminates and the high selectivity to methane affects the performance of these catalysts, especially at low reaction temperatures. In this study, Cu is employed as an effective enhancer of the catalytic performance, promoting the reducibility of Ni, and suppressing methane production through the formation of stable CuNi nanoalloys. The synergy between both metals suppresses consecutive hydrogenation, reaching conversions close to equilibrium and 100% selectivity to carbon monoxide. At 500 °C, the CO yield of the Cu 25 Ni 75 /Al 2 O 3 catalyst was twice that of Ni/Al 2 O 3 , with only half the hydrogen consumption. The formation of CuNi nanoalloys was confirmed by HAADF STEM-EDS, without segregation in monometallic phases even after 30 h time on stream. Similarly, Cu 50 Ni 50 /Al 2 O 3 remained alloyed after the reaction. However, the catalytic activity decreased due to sintering, in agreement with a higher Cu content. This effect was significantly more pronounced for Cu 75 Ni 25 /Al 2 O 3 and Cu/Al 2 O 3 , with formation of large particles and consequent loss of active surface area. Adding Cu to Ni/Al 2 O 3 is an excellent strategy to suppress methane formation and enhance carbon monoxide yield through formation of alloyed nanoparticles.