Abstract: A series of bulk catalysts were synthesized by using NH3.H₂O, NaOH, Na₂CO₃ and mixtures with different ratios of NaOH and  Na₂CO₃ as precipitating agents. Characterization methods such as XRD, BET, TEM, SEM and EPMA are used to analyze the microscopic morphology, pore structure, crushing strength and phase of the synthesized catalysts, and a series of bulk catalysts are evaluated for hydrodesulfurization activity on a small hydrogenation unit. The results show that when a single precipitating agent is used, the bulk catalyst synthesized with NaOH has the best crushing strength and pore structure, the active metal is evenly dispersed, and its hydrodesulfurization activity is the highest. The mixed precipitating agent of NaOH and Na₂CO₃ can expand the pores of the bulk catalyst, which can improve the performance of the catalyst. When the mixed precipitating agent is m( Na₂CO₃): m(NaOH)=2:3, the catalyst has the best physical and chemical properties and activity, the specific surface area of the catalyst is 213 m²/g, the pore volume is 0.308 cm³/g, the bulk density is 1.01 g/cm³, and the crushing strength is 14.9 N/mm. The relative desulfurization activity of the bulk catalyst at this ratio is 1.66 times that of the catalyst using NaOH as the precipitating agent.

Key words: precipitating agent, bulk hydrogenation catalyst, pore structure, active phase, hydrodesulfurization activity