Catalytic performances of large pore Ti-SBA15 supported Pt nanocomposites for the citral hydrogenation reaction

Pt/x%Ti-SBA15 catalysts (x corresponding to the wt.% TiO2 loading in the Ti–SiO2 composite, in the range 25–60%) were synthesized by titanium precursor grafting in preformed mesoporous silica. Materials were characterized by several techniques, including elemental analysis, XRD, TEM and N2-sorption isotherms to achieve structural and textural properties description. Different pore sizes were obtained for the SBA-15 materials, by using or not hexane as swelling agent. The catalytic performances of these original materials were evaluated for the selective hydrogenation of citral (α,β-unsaturated aldehyde), and compared with those of Pt/SBA and Pt/TiO2 P25 reference catalysts. Pt/x%Ti-SBA15 catalysts present high specific surface, with TiO2 nanoparticles and Pt0 clusters located inside the hexagonal mesopore structure of silica. During citral hydrogenation, the selectivity towards unsaturated alcohols (nerol and geraniol) varies as a function of the support nature as follows: Pt/x%Ti-SBA15 > Pt/TiO2 P25 ≫ Pt/SBA. The results are discussed in term of variable metal-support interaction (SMSI) generated by the partial reduction of TiO2 species, this SMSI effect being reported more important over anatase TiO2 nanoparticles dispersed inside the mesostructure than over large crystals encountered in the classical P25 support.

Selectivity to unsaturated alcohols (UA) as function of citral conversion over the nanocomposites catalysts: Pt/TiO2 P25 (■); Pt/SBA8 nm (▴); Pt/25%Ti-SBA8 nm (); Pt/40%Ti-SBA8 nm (●).Figure optionsDownload high-quality image (75 K)Download as PowerPoint slideHighlights
► Pt/x%Ti-SBA15 catalysts were synthesized by Ti grafting in mesoporous silica.
► Catalytic performances were evaluated for the selective hydrogenation of citral.
► SMSI effect: Pt/x%Ti-SBA15 > Pt/TiO2 P25.