I have recently looked up information on the impact of nitrogen and chlorine contents in hydrogenation feedstocks, and I’d like to share it with you all

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I. The impact of Cl in raw materials 1. Forms and sources 1) Organic chlorines in crude oil, present in crude oil at temperatures above 350°C; 2) Inorganic chloride salts in crude oil; 3) Chemical additives used during oil extraction, such as paraffin removers, antifreeze agents, demulsifiers, and soil stabilizers; 4) Chlorine carried by hydrogen gas. 2. Hazards 1) Cl- reacts with the cations in the passivation film; when the Cl- concentration exceeds a critical value, complexes detach from the metal surface, creating cation vacancies. This leads to a thinning of the passivation film at these sites, an increase in the electric field strength within the film, and as a result, the ion current density within the film is much higher than in areas outside those sites. 2) Production of ammonium chlorides from hydrogen sulfide, which can cause equipment blockages. 3) Measures: 1) Injecting water; 2) Monitoring the HCl content in hydrogen to keep it at ≤1 mg/m3, and the chlorine content in raw materials to keep it at ≤1 mg/kg. II. Impact of nitrogen in raw materials 1) Forms of existence: 1) Nitrogen compounds in petroleum fractions are mainly heterocyclic compounds, with their concentration increasing as the boiling point rises. In light fraction oils – there are monocyclic and bicyclic heterocyclic nitrocompounds (such as pyridine, quinoline, pyrrole, indole, etc.). In heavy fraction oils – there are polycyclic nitrogen-containing compounds (such as acridine, carbazole, etc.). 2) Non-heterocyclic carbon compounds are mainly aliphatic amines and nitriles, but in small quantities. 3) Based on their basicity, nitrogen compounds can be divided into basic and non-basic nitrocompounds. Basic nitrocompounds include amines, pyridine, quinoline, acridine, pyridine derivatives, etc. Non-basic nitrocompounds include pyrrole, indole, carbazole, etc. 2) Hazards: 1) Damage caused by N to catalysts: Nitrogen has a strong inhibitory effect on hydroprocessing and hydrocracking catalysts. 2. Organic nitrogen adsorbs rapidly and strongly on cracking catalysts, but desorbs slowly; its inhibitory effect on these catalysts is cumulative ； 3. The presence of organic nitrogen and ammonia increases the dependence of the cracking reaction on hydrogen partial pressure. 4. The presence of organic nitrogen and ammonia causes the cracking reaction to deviate from a normal carbocation reaction, affecting the distribution of the products, that is, the selectivity. The gasoline yield will decrease, carbon deposition will be significant, and the octane rating of gasoline will drop. Ammonia also affects the isomerization performance of the catalyst. 5. Nitrides have a strong inhibitory effect on the hydrogenation saturation of olefins. Nitrides also have an inhibitory effect on desulfurization, which is caused by competing with sulfides for the acidic sites on the catalyst. The inhibitory effect of nitrides depends on their type and concentration; 30 μg/g of nitrides can significantly affect the desulfurization rate. 6. Nitrides are inherently unstable, causing catalyst deactivation through condensation and charring. 2) Ammonia reduces the hydrogen partial pressure, and the formation of ammonium salts can cause equipment to become clogged or corroded. 3) Nitrides in oils can affect stability and cause the color to darken; some organic nitrogens in heavy oils can also be carcinogenic. 3. Measure 1) Increase the partial pressure of hydrogen in the reaction. 2) Increase the acidity of the catalyst to enhance nitrogen resistance. 3) Control the sulfur-to-nitrogen ratio in the raw material to be ≮2.5; when the nitrogen content in the raw material is too high, an appropriate sulfiding agent should be added to neutralize NH3 in the gas phase.