Influence of microwave on structure and composition of fluidized bed catalyst for isobutane dehydrogenation

Key words:  fluidized bed catalyst  microwave  preparation  characterization  isobutane  dehydrogenation

Abstract:

The fluidized bed catalysts of Cr-K/γ-Al₂O_3were prepared by microwave method and characterized. Also the catalytic activities for isobutane dehydrogenation were evaluated, through which the relationship between the structure and performance of the catalysts, as well as the mechanism of microwave effect were analyzed. It was found that the particle size of active constituent on catalyst surface is decreased by microwave method, and the dispersion of active constituent on the supporter is improved in contrast to the catalyst prepared by conventional method. The part active Cr⁶⁺ species occupies sites on/in A1₂O₃ in close vicinity of tetrahedral ²⁷Al in the catalyst prepared by microwave, forming the stable structure of-Al-O-Cr-O-Al-. Also in the catalyst prepared by microwave isolated Cr⁶⁺, mono and polychromate species are more than those prepared by conventional method, which play a key role in the isobutane dehydrogenation. The microwave method can reduce the preparation time of catalyst, increase the activity, high thermal stability, as well as good abrasion resistance, which extends the catalyst life.