Preparation of ZSM-5 nanoparticles supported on carbon substrate

Abstract

Influences of the pore structure and the surface functionality of carbon substrates on the formation of ZSM-5 nanoparticles were studied. The inorganic substance formed on these carbons were identified as ZSM-5 by X-ray diffraction, which also revealed the presence of an amorphous silica phase. The fraction of crystalline phase, which was evaluated from XRD, was not affected by the pore structure; however, inorganic content depended on the pore structure of carbon: i.e. 14–17% for non- and microporous carbons, and 40–55% for mesoporous carbons. TEM observation revealed that the ZSM-5 deposited on these carbon substrates was in the form of nanoparticles with 10–20 nm of diameters. The influence of the surface functionality on the formation of ZSM-5 nanoparticles was also studied with an activated carbon, of which surface functionality was modified by heat-treatment and nitric acid-treatment. A strong dependence of the fraction of crystalline phase on the treatments was observed; i.e. the heat-treatment increased the fraction and the acid-treatment decreased it. Finally, we clarified the controlling factors for the formation of ZSM-5 on carbon materials; the mesoporous surface area of carbon strongly affects the inorganic content and the total acidity of carbon influences the selectivity to ZSM-5 formation.