Process For Ex-situ Presulfiding Of A Hydrotreating Catalyst

The laws of ex-situ presulfiding of a hydrotreating catalyst were studied by means of fixed-bed process. Based on the laws, expansion bed process for sulfidation was investigated. The effects of various factors, such as sulfiding time, temperature, sulfiding and reducing processes, H₂S concentration, H₂ concentration, bed expansion rate and so on, on sulfidation were studied. The process conditions were optimized by orthogonal test. The sulfur content of sulfided catalysts was determined, and the hydrogenation activity of the catalyst was measured using model compounds and practical feeds in microreactor and 100ml reactor undur high pressure. The results showed that it was feasible to sulfurize hydrotreating catalyst ex-situ by expansion bed process. Pyridine-TPD and XRD results indicated that sulfiding temperature, sulfiding and reducing processes affected acidity and agglomerate state of activity species. H2 was necessary for sulfidation. The suitable condition for ex-situ expansion bed presulfiding was follows: sulfiding time ≥10t0; sulfiding temperature = 370℃; H₂S concentration = 5%; H₂ concentration = 5%; bed expansion rate = 12%. Comparison of activity and stability was made between ex-situ expansion bed and in-situ fixed-bed method. The results showed that the activity and stability was better ex-situ. Expansion bed process can be used to sulfurize pyrolysis gasoline two-stage hydrofining catalyst, regenerated wax hydrofining catalyst, prefining catalyst for hydrocraking, and diesel oil hydrofining catalyst. The feasibility of sulfidation using model acidity gas comprising H₂S,H₂,N₂ and CO₂ was studied. The results showed that It was feasible to sulfurize hydrotreating catalyst by acidity gas. The bromine number was still less than 0.5gBr₂/100g when the concentration of CO₂ was up to 1.5 times concentration of H2S.The sulfidation mechanism was investigated by TPS. Temperature programmed sulfiding course comprised absorption, desorption, low temperature sulfiding, deep sulfiding and high temperature reaction etc.