Effect of silicon to aluminium ratio of Ag-ZSM-5 Zeolite catalyst on silver cluster formation

Abstract

This research has the objective to study the effect of Si/AI ratio of Ag-ZSM5 zeolite catalyst on silver cluster formation. In this research, Ag-ZSM5 was prepared at Si/AI ratios of 20,22,28,32,60,100 and 150. The silver cluster, then, was prepared on catalyst by Ag-ZSM5 reduction at different Si/AI ratios with hydrogen at 300 ํC. The characterization of catalyst was performed by means of XRD,XRF,SEM and NH₃TPD. The study of the oxidation state of silver cluster was done by UV-Vis spectroscopy. From the result of UV-Visof catalyst after the reduction with hydrogen at 300 ํC, it was found that at Si/AI ratios of 22,28 and 30, Ag₄²⁺ cluster was formed on catalyst which had the range of absorption between 310-340 nm.. When studying the result of hydrogen concentration to silver cluster formation, it was observed that when increasing hydrogen concentration in the reduction, Ag₄²⁺cluster apparently decreased. However, other Ag species having the range of UV-Vis absorption between 350-480 nm. Increased. It was also found that the suitable hydrogen concentration to Ag₄²⁺ cluster formation was at 3% of hydrogen concentration. When studying the amount of Ag loading to Ag₄²⁺ cluster formation, it was observed the when increasing the amount of Ag loading on catalyst, Ag₄²⁺ cluster was increased.