Effect of K and Ni Promoters on Mo2C/Al2O3 Catalyst for Higher Alcohols Synthesis from Syngas

Abstract

The direct production of higher alcohols from syngas in a single step remains a great challenge. In this work, a series of K and Ni promoted Mo₂C/Al₂O₃ catalysts were prepared by impregnation method to enhance the selectivity of Mo₂C-based catalysts for the one-step conversion of syngas to higher alcohols. The catalysts were continuously tested under the following conditions: 300°C, 3.0 MPa, velocity—11.50 \({\text{Lg}}_{{{\text{Mo}}}}^{{ - 1}}\) h^–1, H₂/CO ratio of 2. The catalysts promoted with K and Ni demonstrated the highest total alcohol selectivity of 67.7%. Moreover, the selectivity for total C₂₊ alcohols reached as high as 56%, with 37% being ethanol. X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) characterization data reveal that K can promote the crystallinity of β-Mo₂C, lower the catalyst reduction temperature and increase the proportion of high-valent Mo on the catalyst surface. In addition, adding Ni as a promoter to the KMo₂C/Al₂O₃ catalyst can generate a synergistic effect to further enhance the catalytic activity and the selectivity of higher alcohols.