Abstract
The effect of steam treatment on Zn/H-ZSM-5 catalysts prepared by an ion-exchange method for non-oxidative ethane dehydroaromatization was investigated. Steam treatment of Zn/H-ZSM-5 after Zn loading improved its catalytic stability on aromatic hydrocarbon formation including benzene, toluene and xylene. Temperature programmed oxidation measurements demonstrated that the steam treatment brought suppression of coke formation and it contributed to the improvement in the catalytic stability. Characterization of the local structure of the zeolites by 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy revealed that dealumination of the framework Al in the MFI structure proceeded by steam treatment. Results of temperature programmed desorption of ammonia indicate the decrease in the amount of acid sites by the steam treatment. The slight changes in Zn content and its electronic state indicated that bared Al related with H+, not with Zn2+, in the MFI structure was preferentially dealuminated by steam treatment. The preferential dealumination led to suppression of coke formation by the selective removal of undesirable Brønsted acid sites.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
