Improved catalytic cracking performance of USY in the presence of metal contaminants by post-synthesis modification

• Zeolite Y with interconnected mesoporous was prepared by post synthesis modification.
• Modified catalysts showed improved catalytic behavior in the presence of contaminant metals.
• The introduction of mesopores increased yields of light oil product with lower coke and gas yields.
• Improved structural properties caused superior performance.

It is well known that pores in catalysts larger than reactant molecules in dimension can ease flow resistance and enhance desorption of the molecules. In this work, mesoporosity was introduced into ultra-stable Y zeolite (USY) via a soft-templating method and the resulting zeolite was applied for preparation of fluid catalytic cracking (FCC) catalysts. The zeolite was extensively characterized by methods including N2 sorption, X-ray Diffraction (XRD), magic angle spinning nuclear magnetic resonance (MAS NMR), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. Results show that the resulting zeolite pores were highly interconnected. Aluminum atoms were re-distributed within the framework while the crystallites were maintained. The effect of contaminant metals (vanadium and nickel) on the activity and product distribution of the prepared catalysts containing modified zeolite was investigated using the micro activity test (MAT). Compared with the parent USY, the modified USY exhibited higher yields of light oil products, much lower coke formation, and lower dry gas yield. Furthermore, the catalysts containing modified USY-10 possessed a higher stability toward metal deactivation than the parent USY. This improved catalytic behavior could be attributed not only to the enhanced diffusion and faster desorption of the adsorbed oil molecules within the pores, but also to the increased accessibility to the acidic sites due to well interconnected pore structures and the large mesopore size.

Modification of a commercial USY introduces interconnected mesopores with bimodal pore size distribution. This developed features cause improvement in the fluid catalytic cracking performance of the zeolite catalyst. Generally, light oil yields increased, while coke and gas yields decreased.Figure optionsDownload as PowerPoint slide