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Organic nitrogen poisons the catalyst. The measures mainly consist of two aspects: first, for FCC feedstock, hydrogenation denitration, complexation denitration, adsorption denitration, solvent extraction denitration, and acid neutralization denitration are employed. Raw material pretreatment process ； Second, the FCC anti-nitrogen process is adopted, along with the use of anti-nitrogen catalysts or additives. Among these measures, hydrodenitration of feedstock is considered the most effective method. However, due to the high investment and operating costs associated with hydrogenation facilities, and especially given the very limited availability of hydrogen sources and hydrogenation capacity in our country, the large-scale industrial application of the FCC feedstock hydrodenitration process is severely restricted. Other raw material denitration processes have disadvantages such as low denitration efficiency, low oil yield, difficulty in recovering the denitration agent, and high denitration costs, and there are few reports of their industrial application. Therefore, improving the process parameters or using nitrogen-resistant catalysts and additives to enhance the ability of FCC units to process high-nitrogen feedstocks is considered a relatively economical and effective approach at present.

The active center of the catalyst is acidic, while ammonia nitrogen is alkaline; this inhibits the natural catalytic activity of the catalyst’s active center, resulting in a decrease in its catalytic efficiency, which appears to be a form of poisoning. However, when the amount of raw material N is low, the basic substances attached to the catalyst detach, and the catalyst regains its activity

The poisoning of hydrocracking catalysts refers primarily to the chemical adsorption of basic nitrogen compounds such as pyridines on the acidic sites, which not only renders the catalyst inactive but also blocks the pores and internal channels. Coking involves the formation of carbon deposits on the surface of the catalyst, covering the active sites; excessive coking leads to pore blockage, preventing reactant molecules from reaching the active sites within those pores. Sintering, on the other hand, causes changes in the catalyst’s structure, resulting in the loss of active sites – in the case of hydrocracking catalysts, this means the aggregation of small metals or an increase in the size of crystals. The acid-base neutralization caused by coking and the chemical adsorption of impurities both constitute temporary poisoning, and the material can regain its activity through air calcination.

Organic nitrogen: Since the active centers of the catalyst are acidic, while ammonia nitrogen is basic, this inhibits the catalytic activity of those active centers, resulting in a reduced catalytic effect; it appears as if the catalyst has been poisoned. However, when the amount of raw material N is low, the basic substances attached to the catalyst detach, and the catalyst regains its activity