Atomic/molecular layer deposition prepared size-selective catalysts and supported nickel catalysts

"Heterogeneous catalysts are widely used because of their many advantages. In this dissertation, the application of atomic/molecular layer deposition (ALD/MLD) in heterogeneous catalyst synthesis and modification was examined.A novel nanostructured size-selective catalyst was synthesized by depositing ultra-thin porous shells on the surface of catalysts. The ultra-thin porous shells were formed by oxidation of aluminum alkoxide films deposited by MLD. The catalytic activity of the size-selective catalyst was improved by introducing gaps between the porous shell and catalytic metal nanoparticles. The introduction of gaps greatly reduced the catalyst activity loss, which resulted from the contact areas between the active sites and porous shells.Ni nanoparticles supported by silica gel particles were prepared by ALD, and the catalyst showed both high activity and selectivity in catalyzing chemoselective transfer reduction of different nitroarenes to produce corresponding aromatic amines.A highly stable and active Ni/γ-Al₂O₃ catalyst was synthesized by depositing Ni nanoparticles on porous γ-Al₂O₃ particles by ALD. The catalyst showed exceptionally high catalytic activity and excellent stability for dry reforming of methane (DRM) reaction. A 4-channel α-Al₂O₃ hollow fiber was also studied as a support for Ni nanoparticles. The Ni/α-Al₂O₃ hollow fiber catalyst showed excellent performance in catalyzing the DRM reaction. The performance of the catalyst was further improved by alumina ALD overcoating on Ni nanoparticle surface to increase Ni-support interaction"--Abstract, page iv.