Metal Particles Synthesized from Atomic Layer Deposition and Their Application in Catalytic Co2 Hydrogenation Reaction( I )

Atomic Layer Deposition (ALD) has been successfully applied to synthesize uniform nanoparticles on oxide supports in catalysis research. The surface-controlled and layer-by-layer process can deposit thin film with an atomic level. The surface of the support or substrate is directly exposed to the metal precursor and then forms nanosized metallic nanoparticles after suitable thermal treatment. The metallic nanoparticles are highly dispersed due to deposition at the atomic level, and the aggregation of metal atoms results from the decomposition of the metal precursor deposited on the support or substrate. In this work, we illustrate a new ALD procedure involving the deposition of Cu(thd)2 or Ni(thd)2 onto silica based supports including SiO2, cage-type SBA-16 and SBA-15 materials. On the other hand, the bimetallic Cu-Ni catalysts will be also prepared using both Cu(thd)2 and Ni(thd)2 deposited on the silica based supports. All Cu, Ni and Cu-Ni catalysts synthesized from ALD process will be applied to catalytic CO2 hydrogenation to form CO and CH4. In the first year, Ni(thd)2 precursor deposited on SiO2, cage-type SBA-16 and SBA-15 materials will be investigated several issues with respect to the mechanism of deposition process, effect of deposition cycles on Ni particle size and sites on silica supports interacting with Ni(thd)2 etc. Our previous study has reported that the deposition of Cu(thd)2 onto the Cu surface of Cu/SiO2 through thermal calcination and reduction at 300°C can successfully lead to decrease the size of Cu NPs from ~28 nm to ~2 nm with a highly uniform size distribution. In the second year, the electron transfer between Cu(thd)2 deposited on Cu surface has been expected to associate with the decomposition of Cu particles and will be deeply investigated. In the third year, the ALD technique will be developed to prepare various bimetallic Cu-Ni deposited on various silica based supports. The active sites and chemical state of all catalysts will discussed in relation to the characterization and activity results of the CO2 hydrogenation reaction. We used CO as a probe molecule to identify the active sites on the ALD catalysts, because it is a good probe molecule for vibrational spectroscopy and can usually provide important information about the surface sites of adsorbed species and the chemical environment of a copper surface. The reaction mechanism of CO2 hydrogenation reaction, active sites for CO2 adsorption will be investigated by the IR and TPD techniques. We will build up a flow reaction system combining FT-IR, TPD and GC-TCD techniques. On the other hand, FT-IR also will be applied to perform the kinetic parameters for the CO2 hydrogenation reaction on ALD surface. The fundamental properties of ALD catalysts will be studied in that precursors binding with porous support, decomposition of precursors on support and formation mechanism of metal particle from precursors. We will focus the study on the fundamentally growth of catalyst particles on surface. The examination of catalysts, by XAS, DR-UV/VIS, TPR, XRD, AES and ESCA etc., may be associated with experimental results of TPD and IR.

Project ID:PA10907-1079
External Project ID:MOST109-2113-M182-002