Design of Catalysts for Selective Hydrogenation of Acrylonitrile via Confining Single Metal Atoms within a C2N Framework

Propionitrile (PN) is a high-value intermediate in the fields of pharmaceuticals, electronic materials, and polymers that can be produced by the selective hydrogenation of the C═C bond in acrylonitrile (AN). However, the strong competitive adsorption between the two unsaturated bonds (C═C and C≡N) in AN makes it a great challenge to obtain target PN compounds with high selectivity over conventional metal catalysts. In this work, we designed efficient catalysts for this important reaction by confining single metal atoms within a C2N framework using first-principles methods. It is found that the electronic properties of the single metal site can be regulated by the specific coordination environment at the pores of C2N to realize selective adsorption of the C═C bond instead of the C≡N bond. The competitive adsorption between C═C and C≡N bonds of AN at the single-atom center can be well understood by a proposed descriptor concerning the nature of the single metal atom and the coordination environment of C2N. Furthermore, the valence electron number of the supported single metal atom can be used as another descriptor to predict the hydrogenation activity. Among all the models investigated, Ni1/C2N and Pd1/C2N are considered to be a highly active and selective catalyst for AN hydrogenation to PN. This work provides insights into the design of selective hydrogenation catalysts for small molecules with multiple unsaturated bonds.