Aluminum‐based composite particles are widely applied complex catalyst materials in oil refining. Due to their tunable shape, porosity, and acidity, they are commonly used for the production of cracking catalysts. Shaping of well‐defined particles remains a challenge for industrial catalyst preparation by spray drying, because catalyst properties must satisfy local demands of a refinery. The selectivity can be modified and the cracking activity enhanced with acid binders, e.g., AlCl3. Therefore, peptization of AlCl3‐containing suspensions with zeolite Y and kaolin was characterized by pH value, 27Al NMR spectroscopy, and zeta potential. A new control strategy for binding of kaolin and zeolite Y in spray drying was developed by adjusting the pH and binder Al/Cl ratio.
Activity, selectivity, and deactivation behavior of catalyst materials determine their efficiency in hydrocarbon conversion processes. For hydrocarbon cracking, the industrial catalyst is an important parameter in reaction technology to produce valuable compounds, e.g. , light olefins (C 3 –C 5 ) and gasoline from crude oil fractions with high molecular weight (C 16+ ). One strategy to enhance the catalytic activity for precracking is increasing the matrix activity, which depends on the used binder and additives. In this work, three binders (water glass, aluminum chloride, and a mixture of colloidal silica with aluminum dihydrogen phosphate) were used in combination with active zeolite Y, kaolin as filler, and ZSM-5 as additive to produce composite materials. Specific surface area and surface acidity measurements were combined with catalytic testing of the formulated samples in order to find the relation between the catalyst morphology and its activity. In addition, constraint index was used as a control parameter for the determination of the shape-selective properties and their correlation with the catalytic activity. The results show that the binders determine the porosity of the matrix and so the accessibility to zeolite pores and active sites. Matrixes with low porosity and activity enhance coke production and deactivate faster than matrixes with mesopores. Furthermore, ZSM-5 modifies the individual morphological and catalytic effects of the binders. Everything considered, the small crystals of ZSM-5 together with mesopores increase the olefins yield, reduce coking, and therefore enhance the performance of the final grain.
Silica‐based composite particles are complex catalyst materials that are widely used in petrochemistry. The preparation of particles that are well defined in form, composition, and chemical and rheological behavior by spray drying of suspensions remains an important industrial challenge. Here, zeolite HY, kaolin, and the cheap binder water glass are used. Experimental and model regimes of slurry peptization are analyzed based on their pH value, zeta potential, and mixing speed to control the process. The results show a pseudoplastic behavior of the silica slurries for zeta potential below 20 mV, which is explained by surface charge, hydroxyls, and pH‐dependent coagulation. Thus, a quick acidification of the slurry, additional mechanic shear, and subsequent pH control during spray drying enable control of peptization kinetics.
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