Methanol conversion to DME as a blue fuel: The beneficial use of ultrasonic irradiation for the preparation of CuO/H-MOR nanocatalyst

Abstract

Methanol conversion to DME was investigated over CuO/H-MOR nanocatalyst prepared by precipitation and/or by precipitation flowed by ultrasonic irradiation methods. BET, XRD, SEM, NH3-TPD and H2-TPR techniques were used to characterize nanocatalysts. The effective ultrasonication factors encountered during carrying out the dehydration of methanol on CuO/H-MOR zeolite catalysts to produce dimethylether are studied in the present work. These factors include: the type of ultrasonication media, the ultrasonication time, and the fixed weight of the solid catalyst per the volume of the ultrasonication liquid media (Wcatalyst/Vliquid ratio). XRD showed that structure of H-MOR is not damaged even after it is loaded with CuO nanoparticles or with ultrasonication. H2-TPR profiles indicated that reducibility of sonicated CuO/H-MOR nanocatalyst is higher than non-sonicated catalyst. It is found that employing ultrasound energy for 60 min has the highest influence on the surface properties of nanocatalyst and its catalytic performance (activity and stability) of CuO/H-MOR catalyst. Surface morphology (SEM) of the sonicated CuO/H-MOR catalysts have clarified that methanol by itself used as an ultrasonication medium gives the best results concerning the homogeneity of particle sizes compared to the non-sonicated catalyst, where large agglomerates and non-homogeneous clusters appeared. Water used as a sonication medium showed many large agglomerates in addition to some smaller particles resulted in low catalytic activity. The different alcohols and (Wcatalyst/Vliquid) ratio were examined to give precise correlation with the catalytic activity of the sonicated CuO/H-MOR zeolite catalyst. These findings certified that ultrasonication has a deep effect on the surface morphology and hence on the catalytic behavior of the dehydration of methanol to DME. NH3-TPD shows that ultrasound irradiation has enhanced the acidity of CuO/H-MOR catalyst and hence it's catalytic performance for DME formation.