In this contribution, nanocatalysts with rather diverse architectures were designed to promote different intimacy degrees between Cu and SiO₂ and consequently tune distinct Cu-SiO₂ interactions. Previously synthesized copper nanoparticles were deposited onto SiO₂ (NPCu/SiO₂) in contrast to ordinarily prepared supported Cu/SiO₂. NPCu@SiO₂ and SiO₂@Cu core-shell nanocatalysts were also synthesized, and they were all bulk and surface characterized by XRD, TGA, TEM/HRTEM, H₂-TPR, XANES, and XPS. It was found that Cu⁰ is the main copper phase in NPCu/SiO₂ while Cu²⁺ rules the ordinary Cu/SiO₂ catalyst, and Cu⁰ and electron-deficient Cu^δ+ species coexist in the core-shell nanocatalysts as a consequence of a deeper metal-support interaction. Catalytic performance could not be associated with the physical properties of the nanocatalysts derived from their architectures but was associated with the more refined chemical characteristics tuned by their design. Cu/SiO₂ and NPCu/SiO₂ catalysts led to the formation of furfuryl alcohol, evidencing that catalysts holding weak or no metal-support interaction have no significant impact on product distribution even in the aqueous phase. The establishment of such interactions through advanced catalyst architecture, allowing the formation of electron-deficient Cu^δ+ moieties, particularly Cu²⁺ and Cu⁺ as unveiled by spectroscopic investigations, is critical to promoting the hydrogenation-ring rearrangement cascade mechanism leading to cycloketones.

A collection of Al-SBA-15 mesoporous catalysts (Si/Al = 13–174) was investigated to overcome typical accessibility constraints of microporous solids. ²⁷Al MAS NMR confirmed the existence of tetrahedrally coordinated Al in the catalyst’s framework, and the fraction of such species increased as the Si/Al ratio decreased. Brønsted acidity followed the same pattern found using n-propylamine thermodecomposition. Mesoporous catalysts with lower Si/Al ratios exhibited a higher affinity to water as quantitatively determined using water adsorption experiments. Those surface properties were correlated to the catalytic performance on oleic acid esterification. The introduction of Al into the SBA-15 framework significantly improved esterification activity, leading to conversions ranging from 70 to 93%. This was explained by the acidity engendered upon Si substitution by Al. However, a turning point from which activity started dropping was registered and it was proposed to be associated with catalyst hydrophilicity. The balance between acidity and hydrophilicity was unveiled to be of paramount importance to accomplish the best catalytic efficiency and uppermost biofuel yield. Catalyst activity was also assessed for the esterification of stearic and linoleic acids. Higher conversion rates were accomplished with unsaturated fatty acids (oleic acid > linoleic acid > stearic acid) due to the higher reactivity of the carboxylic acid moieties as a consequence of the polarity of the double bonds in the carbon chain.