Utilizing Colloidal Silica and Aluminum-Doped Colloidal Silica as a Binder in FCC Catalysts: Effects on Porosity, Acidity, and Microactivity

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• 作者：Brian T. Holland ; Velu Subramani ; Santosh K. Gangwal
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2007
• 出版时间：June 20, 2007
• 年：2007
• 卷：46
• 期：13
• 页码：4486 - 4496
• 全文大小：460K
• 年卷期：v.46,no.13(June 20, 2007)
• ISSN：1520-5045

文摘

This paper reports on the synthesis and characterization of fluid catalytic cracking (FCC) catalysts using twodifferent colloidal silica materials as binders, where one was doped with 2 wt % Al₂O₃ and the other waswithout any dopant. The physicochemical properties such as attrition resistance, particle size distribution,surface areas, porosity, morphology, chemical environment, and acidity were investigated employing variousanalytical and spectroscopic techniques such as N₂ sorption, scanning electron microscopy, transmission electronmicroscopy, ²⁹Si and ²⁷Al MAS NMR, and temperature programmed desorption of ammonia (NH₃-TPD). Itwas observed that the FCC catalysts synthesized using colloidal silica have larger particle sizes than thatsynthesized using sodium silicate (baseline catalyst) as a binder and lower than that of a commercial FCCcatalyst. They also exhibit relatively lower attrition resistance than the commercial and the baseline FCCcatalysts; however, they exhibit higher BET and matrix surface area than the commercial and the baselineFCC catalysts. Use of aluminum doped colloidal silica provided increased acidity of the matrix at low levelscompared to the commercial FCC catalyst, which contained twice the amount of aluminum. This led to increasedactivity and selectivity in microactivity testing (MAT), especially for gasoline yield (53.28 wt %), comparedto colloidal silica as a binder (49.66 wt %). In addition, the FCC catalysts made with aluminum doped colloidalsilica offered similar dry gas amounts (1.34 wt %) and slightly higher coke values (2.98 wt %) compared tothat made with Al-free colloidal silica, which produced 1.42 and 2.59 wt % dry gas and coke, respectively.Both these values are significantly lower than the commercial FCC catalyst, possibly as a result of the uniqueporosity observed with the FCC catalysts formulated with colloidal particles.