Enhanced Catalytic Activity of Modified ZSM-5 Towards Glucose Isomerization to Fructose.

Abstract

The present study focuses on generating mesopores within H-ZSM-5 (H-Z) zeolite via desilication and dealumination to incorporate Lewis acidic metal, such as Sn, into the framework (Sn4 ZS180 A15 ) to catalyse glucose isomerisation. Sn4 ZS180 A15 possesses enhanced surface area (457 m2 g-1 ), mesopore volume (0.585 cm3 g-1 ) and a high weak-medium to strong acidic sites ratio, compared to parent H-Z (395 m2 g-1 ; 0.174 cm3 g-1 ). DRS-UV-Vis and XPS results corroborate Sn incorporation into the framework of Sn4 ZS180 A15 , based on the absorbance peak around 200-220 nm and peaks appearing at 495.8 and 487.4 eV, respectively. Sn4 ZS180 A15 exhibits higher catalytic activity towards glucose isomerisation in ethanol-water at 110 °C, yielding 44.2 % fructose with 80.0 % selectivity. Conversely, the parent H-Z afforded negligible glucose conversion with a fructose yield of <1 % under identical conditions. Moreover, Sn-incorporated on dealuminated (Sn4 ZS0 A15 ) and desilicated (Sn4 ZS180 A0 ) catalysts give a low yield of fructose (7-10 %), signifying the requirement of the desilication-dealumination process before incorporating Sn into the framework.