The focus of this thesis was to design heterogeneous ruthenium (Ru)-based catalysts with well-defined structures, and to study the correlation between their structures and their catalytic performance for the liquid phase hydrogenation of bio-derived organic acids and aldehydes. We evaluated three colloidal-based routes for the preparation of the supported Ru catalysts, and concluded that polyol reduction using polymeric stabilizers gave the best results for synthesizing monodisperse colloidal Ru NPs. Sonication-assisted deposition also gave the best results for anchoring the colloidal NPs onto mesoporous silica support (MSU-F). Activation of the supported Ru NPs to remove the stabilizer was explored using three different thermal treatments. The solid catalysts were then characterized and their reactivity was assessed by the aqueous phase hydrogenation of pyruvic acid as a model reaction. These studies showed that argon-protected calcination is the most efficient procedure for activating Ru nanocatalysts on MSU-F support.We then investigated the effect of particle size on the catalytic performance of the supported Ru NPs, using the liquid phase hydrogenation of cinnamaldehyde (CAL) as the model reaction. Colloidal Ru NPs of various sizes were synthesized by adjusting the polyol reduction parameters. It was observed that the formation of Ru NPs can occur under either thermodynamic or kinetic control, with the final size of the NPs determined by a balance between the two pathways. After sonication-assisted deposition of the size-tuned Ru NPs on MSU-F and subsequent Ar-protected calcination, we observed well-dispersed Ru NPs on the support with no agglomeration or damage to the ordered structure of the support. The uniformity and crystallinity of the supported Ru NPs in each catalyst also improved with the thermal activation procedure. The hydrogenation of CAL over supported Ru NPs produced cinnamyl alcohol (COL), hydrocinnamaldehyde (HCAL), and hydrocinnamyl alcohol (HCOL), with COL the major product. Varying the size of the NPs did not affect the apparent activation energy or product selectivity, suggesting that the reaction pathway was independent of particle size. However, particle size changed the density of active sites per unit surface area, thus affecting the activity of the catalysts.Finally, we examined the influence of the metal composition of a series of Ru-Pd bimetallic catalysts on their performance for CAL hydrogenation. The colloidal bimetallic NPs were synthesized by polyol reduction, deposited on MSU-F support by sonication-assisted deposition, and activated through Ar-protected calcination. The NPs in each catalyst were well dispersed on the MSU-F support with an alloyed crystal structure. The bimetallic NPs produced higher turnover frequencies (TOF) for CAL hydrogenation than the monometallic Ru NPs, presumably due to synergetic effects. In contrast to CAL hydrogenation over Ru NPs which produced COL as the major product, the reaction over bimetallic NPs and monometallic Pd NPs produced HCAL or HCOL as the major product, with the ratio of HCAL to HCOL production dependent on the metal composition of the catalysts. In summary, this research has provided new routes for the rational design of Ru-based heterogeneous catalysts with well-defined structures, and new insights into the relationship between structure and catalytic performance of Ru-based catalysts for multiphase hydrogenation of bio-based organic acids and aldehydes.
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