Structural Changes in steamed HY: Experimental and Theoretical Study

GABRIELA TONETTO; MARÍA LUJÁN FERREIRA; HUGO DE LASA

París

Congreso; XIII Congreso Internacional de Catálisis; 2004

The present study discusses the shape selectivity properties of USY zeolite crystallites based in molecular simulation, catalytic experiments of model compounds and catalyst characterization. Typical FCC catalysts are prepared with different HY crystallite sizes (0.4 and 0.9 m m) and are structurally and chemically characterized using nitrogen and argon adsorption/desorption isotherms, temperature-programmed desorption of ammonia and infrared spectroscopy. This characterization of the catalysts is carried out before and after the hydrothermal treatment (steaming) of the catalyst is performed. Pore size distribution analysis demonstrates the effect of the steaming treatment in the Y zeolite window enlargement. The influence of structural changes that the steam treatment provides to the FCC-type catalysts in terms of reactivity is studied using the catalytic conversion of 1,2,4-trimethylbenzene in a novel fluidized CREC riser simulator. It is proven that steaming enlarges zeolite windows and influence 1,2,4-TMB product distributions with these effects being assigned to transition state shape selectivity. This observation is consistent with molecular mechanics calculations.