Hydrothermal reduction synthesis of K-Ni-Mo-based catalyst and its catalytic performance for higher alcohol synthesis from syngas

A series of non-sulfurized K-Ni-Mo-based catalysts with close contact between Ni and K₂MoO₄ were prepared by hydrothermal reduction for higher alcohol synthesis from syngas. The as-prepared catalysts were characterized by XRD, N₂ adsorption-desorption, H₂-TPR, HR-TEM, SEM-EDS, XPS, H₂-TPD, CO-TPD and CO₂-TPD techniques. The results indicate that the introduction of K facilitates the formation of the K₂MoO₄ phase while brings about a decrease of NiMoO₄. It can significantly assist the non-dissociative activation of CO for insertion and subsequently alcohol formation. Moreover, the addition of K increases the surface basicity, which leads to more amount of basic hydroxy groups on the catalytic surface. The catalytic basicity ameliorates the production of alcohols. In particular, the K_0.4-Ni-Mo catalyst shows the best catalytic behavior with CO conversion of 19.6%, total alcohol selectivity of 57.8% and C₂₊ alcohol selectivity in the total alcohols of 66.5% at GHSV of 5000 h⁻¹, 240 °C, and 5 MPa.