Unveiling the First Use of an External True Sulfidation Hydrogenation Catalyst

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Recently, a new type of catalyst developed by the Research Institute of Petrochemical Science (hereinafter referred to as the RIPS) – an external true sulfided hydrogenation catalyst – was successfully applied in the 2.2 million tons per year diesel liquid-phase hydrogenation unit at Sinopec’s Anqing branch. This is the first hydrogenation unit in China to be put into operation using external true-sulfided hydrogenation catalysts; the catalyst model used in this operation is the external true-sulfided RG-1/RS-2100/RS-2200 series catalysts. There are various methods of sulfidation. Regarding the differences in the methods used to sulfidize hydrogenation catalysts, Li Mingfeng, vice president of the China Petroleum Research Institute, said that there are currently three methods for sulfiding hydrogenation catalysts. The first method is in-situ sulfidation, which is widely used in oil refining companies; it involves using a sulfiding agent and hydrogen, and it takes 1 to 2 days to sulfidize the hydrogenation catalyst ； The second method is external pre-sulfidization, in which the sulfiding agent is pre-loaded into the oxidized catalyst outside the reactor. After it is loaded into the hydrogenation reactor, although there is no need to inject the sulfiding agent at the site of operation, hydrogen and a sulfiding carrier oil still need to be used for 1–2 days to convert the oxidized metal into sulfided metal ； The third method is external true sulfidation, in which the oxidized catalyst is directly subjected to true sulfidation using a sulfiding agent and hydrogen outside the reactor. Once the catalyst acquires true hydrogenation activity, it is then loaded into the hydrogenation reactor to process feed oil, thereby reducing the safety and environmental challenges faced by refineries during startup, shortening the startup time, and increasing the economic benefits for these enterprises. Compared with traditional external pre-sulfidation methods that involve the use of sulfur-loaded catalysts, external true sulfidation technology offers more significant advantages. There are many advantages to true sulfidation outside the reactor. \"After years of effort, the Chinese Academy of Sciences has developed the e-Trust technology for true sulfidation of hydrogenation catalysts outside the reactor; all hydrogenation catalysts, including new ones and regenerated ones, can be subjected to true sulfidation in this manner.\" ”Li Mingfeng said. The process of loading the true sulfided hydrogenation catalyst outside the charger is simple. Li Mingfeng said that the truly sulfided catalysts are all packaged in containers, with each container holding 2 cubic meters of material. A crane is used to lift the container to the top of the reactor, after which a valve is opened at the bottom of the container; the catalyst then falls directly into cloth bags and enters the reactor. This method offers a higher filling efficiency compared to the traditional use of ton bags. “In addition to the high loading efficiency, the time required for the airtightness testing process when starting up with an external true sulfided hydrogenation catalyst is also **reduced**. ”Liu Feng, the person in charge of the development of external true sulfidation technology, said that in order to prevent hydrogen embrittlement, the high-pressure hydrogenation reactor in Anqing Petrochemical’s diesel hydrogenation unit must have its wall temperature raised above 93°C before pressure is increased. Therefore, during the airtightness testing process, it is necessary to raise the temperature of the catalyst bed in the reactor in order to increase the wall temperature of the reactor as well. As hydrogenation units place increasing demands on the activity of hydrogenation catalysts, in order to enhance catalyst activity, ultra-deep hydrogenation catalysts developed by patent holders around the world currently employ special preparation techniques. The catalyst cannot withstand high temperatures before sulfidation; otherwise, it will affect the sulfidation process inside the reactor and significantly impact the heating time of the reactor walls. However, the truly sulfided catalysts had already been fully sulfided outside the reactor, allowing the bed temperature to be increased appropriately. With the operation of these truly sulfided catalysts, raising the temperature at the highest point of the bed significantly shortened the time required for the reactor walls to heat up. Previously, it took nearly 4 days from the start of heating up to when the reactor walls reached a temperature of over 93°C; this time, the reactor wall temperature met the required level in less than 24 hours. “Furthermore, we analyzed the gas composition of the circulating gas during both the nitrogen gas sealing and hydrogen gas sealing processes, and no release of toxic or harmful waste gases such as hydrogen sulfide or carbon monoxide was detected; nor was the formation of acidic water observed during the heating process for sealing. ”Liu Feng said. Wide range of application scenarios. Liu Feng stated that through a comprehensive comparison of the operation processes for Anqing Petrochemical’s 2.2 million tons per year diesel liquid-phase hydrogenation unit: operation using oxidized catalysts in the 2016 cycle and operation using truly sulfided catalysts in the 2018 cycle – it was found that, compared to using oxidized catalysts in 2016, the use of truly sulfided catalysts resulted in no wastewater or exhaust gas emissions. Qualified products with a sulfur content of less than 10 μg/g could be produced as early as 27 hours after feedstock arrival, which saved 5 days in total operation time and reduced operational costs (in terms of material and energy consumption) by over 3 million yuan. Starting up with a truly sulfided catalyst offers significant advantages in terms of safety, environmental protection, startup time, and startup costs. “The National V diesel produced using an ex-situ true sulfided hydrogenation catalyst system has a sulfur content that is generally kept within the range of 3 μg/g to 6 μg/g. Overall, based on the comparison of initial activity, the performance of catalysts using external true vulcanization hydrogenation is slightly better than that of catalysts using internal vulcanization. ”Liu Feng said. Li Mingfeng also stated that due to their significant advantages in terms of ease of operation, truly sulfided catalysts can be used in hydrogenation units where temporary and rapid catalyst replacement is required. For example, in the future, the operation cycle of hydrogenation units used for producing National VI diesel is likely to fail to meet the goal of continuous operation for 4 years, and they will not operate in sync with other related units. To avoid affecting the operation of those other units, plans for rapid catalyst replacement are necessary; such approaches can also be used in situations where online replacement of hydrogenation catalysts is required. For example, processes such as fluidized-bed hydrogenation require the on-line replacement of the hydrogenation catalyst, and the new catalyst used must possess genuine hydrogenation activity. In hydrocrackers for residue processing, the deactivation rate of demetallizing agents is significantly faster than that of desulfurization and decarburization agents; if a catalyst in its true sulfided state can be installed after the demetallizing agents become deactivated, operations can resume immediately, thereby extending the service life of the catalysts in the entire installation.