Methods for enhancing acid sites of FCC catalysts

Abstract

The present invention discloses aqueous methods for enhancing the acid sites of fluid catalytic cracking (FCC) catalysts. The methods comprise the steps of contacting an FCC catalyst, either spent or fresh, with an aqueous solution comprising water, an inorganic acid substantially free of chloride and aluminum. The acid is preferably sulfurous or sulfuric acid. The aluminum is provided by an aluminum source selected from the group consisting of the alumina trihydrates and aluminum oxide. Chloride contamination of the aluminum source should be minimal, preferably less than about 1000 ppm chloride, more preferably less than about 200 ppm chloride. The pH of the aqueous solution is adjusted to about 3-12 by the addition of a sufficient quantity of ammonium hydroxide. The FCC catalyst is added to this solution, preferably with stirring, in a weight ratio of about 1 part catalyst to about 1-10 parts water to prepare an aqueous slurry. Upon stabilization of the pH of the aqueous slurry, enhancement of the acid sites of the catalyst is achieved and the catalyst may be separated from the slurry and, if desired, washed. This simple, aqueous process reduces the level of many metal poisons on the FCC catalyst and produces a catalyst having an enhanced number of acid reaction sites.

Description

Background of the invention [0001] Ⅰ. field of invention [0002] The present invention relates to a process for preparing fluid catalytic cracking catalysts having increased acid sites. More specifically, it is an object of the present invention to prepare improved fluid catalytic cracking catalysts by the aqueous process by contacting the catalyst under given conditions with an aqueous solution containing an aluminum source of specified characteristics. [0003] Ⅱ. background description [0004] Catalytic control processes, including fluid catalytic cracking, are valuable refining processes for upgrading heavy hydrocarbons into higher value products. In particular, the cracking of hydrocarbon feedstocks to produce hydrocarbons with preferred octane numbers and boiling ranges in the gasoline range has gained widespread use. Such cracking employs various solid catalysts, generally containing at least one synthetic crystalline material, to produce more valuable end produc...

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