Study on preparation of spherical Al2O3 by nucleation-coating method and its application in propane dehydrogenation
Aluminum oxide(Al2O3)support is one of the most widely used catalytic materials,and replacing linear Al2O3 support with spherical Al2O3 support has become a major trend,so it is urgent to develop novel green and feasible methods for producing spherical Al2O3 support.Firstly,spherical Al2O3 with excellent sphericity,high strength and large specific surface area was prepared by nucleation-coating method:using pseudo boehmite as the raw material,nitric acid as the peptiser and hydroxypropyl methyl cellulose as the binder to optimize the rolling ball method.The effects of water-powder ratio(mass ratio),acid-powder ratio(mass ratio),binder content(mass fraction)and blasting time on the strength and pore structure of spherical Al2O3 were investigated by characterization methods such as X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results show that spherical Al2O3 with uniform particle size,high yield and high average compressive strength of 43.0 N can be prepared by controlling the acid-powder ratio of 0.050,water-powder ratio of 0.88,binder content of 3%(mass fraction)and blasting time of 5 min.Furthermore,spherical and powder PtSn/Al2O3 catalysts were prepared and applied to propane dehydrogenation at 618℃,H2 and C3H8 flow rate of 3.6 mL/min and 6.0 mL/min,respectively.The spherical PtSn/Al2O3 catalyst shows similar activity and selectivity as the powder PtSn/Al2O3 catalyst.Nucleation-coating method is green and efficient to prepare spherical Al2O3 support,which provides inspirations for localization of spherical Al2O3 support.
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