Three transition metal-like facet centered cubic structured transition metal nitrides

γ-Mo

2

N

β-W

2

N and δ-NbN

are synthesized and applied in the reaction of CO

2

hydrogenation to CO. Among the three nitride catalysts

the γ-Mo

2

N exhibits superior activity to target product CO

which is 4.6 and 76 times higher than the other two counterparts of β-W

2

N and δ-NbN at 600 ℃

respectively. Additionally

γ-Mo

2

N exhibits excellent stability on both cyclic heating–cooling and high space velocity steady state operation. The deactivation degree of cyclic heating–cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.

In-situ

XRD and kinetic studies suggest that the γ-Mo

2

N itself is able to activate both of the reactants CO

2

and H

2

. Below 400 ℃

the reaction mainly occurs at the surface of γ-Mo

2

N catalyst. CO

2

and H

2

competitively adsorbe on the surface of catalyst and CO

2

is the relatively stronger surface adsorbate. At a higher temperature

the interstitial vacancies of the γ-Mo

2

N can be reversibly filled with the oxygen from CO

2

dissociation. Both of the surface and bulk phase sites of γ-Mo

2

N participate in the high temperature CO

2

hydrogenation pathway.