Magnetic Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) as Catalysts for the Selective Hydrogenation of Cinnamaldehyde. Effect of the Nature of the Metal Oxide

Abstract

The type of metal oxide affects the activity and selectivity of Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) catalysts on the hydrogenation of cinnamaldehyde. The double shell structure design is thought to protect the magnetic Fe2O3 cores, and also act as a platform for depositing a second shell of TiO2, SnO2 or CeO2 metal oxide. To obtain a homogeneous metallic dispersion, the incorporation of 5 wt % of Pt was carried out over Fe2O3–SiO2–MeO2 (Me = Ti, Sn, Ce) structures modified with (3-aminopropyl)triethoxysilane by successive impregnation-reduction cycles. The full characterization by HR-TEM, STEM-EDX, XRD, N2 adsorption isotherm at −196 °C, TPR-H2 and VSM of the catalysts indicates that homogeneous core-shell structures with controlled nano-sized magnetic cores, multi-shells and metallic Pt were obtained. The nature of the metal oxide affects the Pt nanoparticle sizes where the mean Pt diameter is in the order: –TiO2–Pt > –SnO2–Pt > –CeO2–Pt. Among the catalysts studied, –CeO2–Pt had the best catalytic performance, reaching the maximum of conversion at 240 min. of reaction without producing hydrocinnamaldehyde (HCAL). It also showed a plot volcano type for the production of cinnamic alcohol (COL), with 3-phenyl-1-propanol (HCOL) as a main product. The –SnO2–Pt catalyst showed a poor catalytic performance attributable to the Pt clusters’ occlusion in the irregular surface of the –SnO2. Finally, the –TiO2–Pt catalyst showed a continuous production of COL with a 100% conversion and 65% selectivity at 600 min of reaction.

Recent Advances in Selective Hydrogenation of Cinnamaldehyde over Supported Metal-Based Catalysts

“…The Langmuir–Hinshelwood (L-H) adsorption kinetic model has been widely adopted for studies of the reaction of CAL hydrogenation over catalysts. − For a batch reactor system, the reaction rates fit to the first-order reaction with respect to H 2 pressure over Pt, ,− Pd, Ni, , Co, and Ir-based catalysts, indicating a zero-order dependence on CAL concentration. The concentration of H 2 in the solvent dominates the reaction rate, and the solvent with higher solubility of H 2 will promote the reaction rate.…”

Applications of Magnetic Nanomaterials in Heterogeneous Catalysis

“…Pt nanoparticles were introduced to the surface of the double-shell-coated Fe 2 O 3 nanoparticles . Two shells can greatly protect the Fe 2 O 3 nanoparticles.…”

“…Pt nanoparticles were introduced to the surface of the doubleshell-coated Fe 2 O 3 nanoparticles. 88 Two shells can greatly protect the Fe 2 O 3 nanoparticles. Dinamarca et al demonstrated that Fe 2 O 3 −SiO 2 −CeO 2 −Pt showed high selectivity to COL for the hydrogenation of CAL, where CeO 2 as the second shell can control the configuration of Fe 2 O 3 −SiO 2 .…”