Structure and acidity of REHY Zeolite in FCC catalyst

Document Type

Article

Publication Date

12-1-2005

Abstract

In the FCC process, REHY is the main active component of cracking catalyst for reducing naphtha olefins. The loading, position, occupation and coordination of RE3+ on HY zeolite directly affect not only the acid amount (density of acid centers), acidic intensity, and the ratio of Brönsted acid to Lewis acid, but also the catalytic activity of the FCC catalyst. To understand the effect of RE3+ distribution and positions in Y zeolite on the acidity of the catalyst, the REHY zeolite was characterized. The distribution of RE3+ outside the framework of the Y zeolite was determined by polycrystalline XRD with the Rietveld method. RE3+ replaced Na+ or H+ in the Y zeolite and situated at SII/′ sites in β cages. As a result, they made the framework of Y zeolite more stable and improved the hydrothermal stability. When RE3+ situated at SI/′ sites polarized water situated at SII/′ sites, the mild strong acid sites of the Y zeolite were increased, and the reduction of acid sites in the Y zeolite was slowed down. The determination of the REHY structure showed that 11 RE SI/′ in every cell of the Y zeolite in FCC catalyst should be the optimum value, and they all should be situated at SI/′ sites in β cages.

Publication Source (Journal or Book title)

Chinese Journal of Catalysis

First Page

301

Last Page

306

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