Highly activeMCM-41 supported nickel phosphide catalysts for hydrodesulfurization (HDS) were synthesized by two different phosphorus sources, in which the surface of Ni2P catalysts were modified by air instead of being passivated by O-2/N-2 mixture. In addition, the catalysts need not be activated with flowing H-2 (30 ml center dot min(-1)) at 500 degrees C for 2 h prior to reaction as traditional method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N-2-adsorption specific surface areameasurements and CO chemisorptionwere used to characterize the resulting catalysts. The effect of modificationwith air on the surface of the catalysts for HDS performance was investigated. Results showed that the surface modificationwith air can promote the formation of smaller Ni2P particles and more active Ni sites on surface of catalysts. At 3.0 MPa and 613 K, the dibenzothiophene (DBT) conversion of the catalysts modified with air was 98.7%, which was 7.1% higher than that of catalyst passivated by O-2/N-2 mixture. The higher activities of Ni2P(x)/M41-O catalysts can be attributed to the smaller Ni2P particles sizes and the increased hydrogen dissociation activity due to the surface modification. (C) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.