Computational and experimental study of the second metal effect on the structure and properties of bi-metallic MeMoS-sites in transition metal sulfide catalysts

Bimetallic (Me)MoS2 (Me = Nb, Fe, Co, Ni) sulfide systems, both modified and non-modified by potassium, were investigated by the DFT method. Geometric and electronic structures of active sites were compared in terms of CO and hydride hydrogen adsorption. Most of the studied metals are electron density acceptors on the S-edge of the crystallite, which inhibits hydride hydrogen adsorption and deactivates the S-edge. The CO adsorption energy on the Me-edge decreased in the order Fe > Co > Ni. Computational data were verified by experimental tests in syngas conversion. Modification by potassium was shown to hinder sigma-bonding of the adsorbed molecule and to stabilize hydride hydrogen.