The effects of arsenic and silicon on hydrogenation catalysts

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Ø Arsenic and silicon are poisons for hydrogenation catalysts; even a small amount of these elements deposited on the catalyst can significantly reduce its activity. Arsenic is brought in with crude oil, and is mostly contained in the light and heavy naphthas of crude oil. Arsenic is highly toxic to hydrogenation catalysts; even a deposition of 0.5% arsenic on catalysts with high resistance to arsenic poisoning can result in a loss of more than 30% in activity, while for catalysts with low resistance to arsenic poisoning, a deposition of 0.1% arsenic can lead to a 50% decrease in activity. The form of arsenic deposition is arsenide, and regeneration is generally not carried out when the arsenic content on the catalyst exceeds 500–1000 μg/g. Arsenic is not deposited evenly within the hydrogenation catalyst bed; instead, its deposition amount decreases gradually from top to bottom along the reactor axis. It is generally believed that the arsenic content in the feed oil that hydrogenation catalysts can tolerate is less than 200 μg/Kg. For raw materials with high arsenic content, an arsenic removal agent can be loaded at the top of the reactor. This post was last edited by Zhenzhen Youci on 2009-4-16 at 16:47.]