Selectivity of silica-alumina matrices

CHENG AND RAJAGOPALAN Selectivity of Silica-Alumina Matrices... 

A model for the amperometric enzyme electrode, obtained by digital simulation, has been applied to D-glucose oxidase immobilized within polyacrylamide gel. D-Glucose oxidase was selected for screening a number of inorganic supports as matrices for immobilization. The activity of the immobilized enzyme on matrices of silica-alumina (with or without nickel), or silicon carbide, or Kieselguhr depended on the size and nature of the supporting particles. 

The catalyst must also have acidity in the matrix in order to reduce the molecular weight of molecules too large to enter the zeolite and in order to also convert heavy-cycle oil to light-cycle oil. Our studies have established that good balance in acidity between the matrix and the zeolite tends to enhance selectivity. A stable matrix acidity is also required, and here a high alumina silica-alumina cogel was selected due to its demonstrated stability in the pre-zeolite era. Certainly many other acidic matrices could probably be substituted. 

To improve bottoms cracking activity and coke selectivity of RFCC catalysts, novel zeolites and matrices have been developed recently. Commercial results showed that both VRCC-1 catalyst containing SOY zeolite and RSC-2006 based on silica modified alumina matrix have demonstrated excellent bottoms cracking capability and... 

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