PhD Oral Qualifying Examination : Core@shell metal catalysts for high temperature hydrocarbon conversion reactions

Speaker Sonali Das (Supervisor(s): A/Prof Sibudjing Kawi and A/Prof Hidajat Kus)

Host Department of Chemical and Biomolecular Engineering

Date/Time 19 Jun - 19 Jun, 10.00am

Venue E5-02-32 , Faculty of Engineering, National University of Singapore

Synopsis

Activity and selectivity are crucial parameters to consider for an effective catalyst. However, for practical application, it is necessary for the catalyst to maintain its properties over time. A major cause of poor stability of nano-catalysts is sintering whereby, large catalyst nanoparticles grow at the expense of smaller nanoparticles, leading to an overall loss of active surface area and activity. Such processes are especially common under demanding reaction conditions like high temperatures. Metal sintering also affects the product selectivity, e.g, for high temperature hydrocarbon reforming reactions, sintering causes a rapid increase in the formation of coke by-product, leading to catalyst deactivation and severe operational concerns. This study focuses on developing core@shell structured catalysts to prevent metal sintering and subsequent coke formation in high temperature hydrocarbon conversion reactions. Here, bifunctional core@shell catalysts have been developed where the shell not only protects the active metal core from sintering but also actively participates in coke combustion and removal. A multi-core@shell Ni-SiO2@CeO2 catalyst was developed, which showed exceptional stability, coke resistance (no coke detected after 72 hrs) and increase in activity (2-3 times that of Ni-SiO2 & Ni-CeO2) in Dry Reforming of Methane under severe coking conditions. In future, such bifunctional core@shell catalysts will be developed for steam reforming of biomass tar. The effect of the shell composition and morphology on the overall catalytic performance and reaction mechanism will be investigated. The effect of the shell porosity on the overall catalytic activity and sinter resistance will also be studied.

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