Poison Tolerance to the Selective Hydrogenation of Cinnamaldehyde in Water over an Ordered Mesoporous Carbonaceous Composite Supported Pd Catalyst

Abstract

A coordination-assisted pyrolysis procedure was adopted to encapsulate palladium (Pd) nanoparticles in a mesoporous carbonaceous matrix. X-ray diffraction and transmission electron microscopy measurements revealed that approximately 2.5 nm nanoparticles were highly dispersed inside the well-ordered porous framework. High-resolution TEM and temperature-programmed hydride decomposition analysis demonstrated the formation of interstitial carbon in the Pd lattice. Diffuse reflectance infrared Fourier transform spectroscopy indicated that carbon species could be deposited on low-coordinated surface sites of the Pd particles. This catalyst exhibited high activity in the selective hydrogenation of cinnamaldehyde (CAL) at 80 °C under an H2 pressure of 1.0 MPa (turnover frequency (TOF) of 2.4 s–1) to produce hydrocinnamyl aldehyde with high selectivity (HCAL; approximately 80%) in water and could be reused eight times with no clear activity loss. A trapping agent poisoning experiment using solid SH-SBA-15 revealed unobvious leaching of Pd into the solution. Exposure to thiourea with a S:Pd ratio of 0.1 resulted in slight activity and undetectable selectivity losses over the current catalyst in the selective hydrogenation of CAL at 80 °C under an H2 pressure of 1.0 MPa. However, a 50% activity loss was observed for commercial Pd/C. Even after an increase in the thiourea concentration to a S:Pd ratio of 3, the TOF remained at 1.9 s–1 with a negligible effect on the HCAL selectivity. Nearly complete deactivation of Pd/C occurred upon high exposure to thiourea. DFT calculations showed that the presence of surface or subsurface carbon can enhance the poison tolerance of the encapsulated Pd catalysts. The enhanced hydrogenation activity and strong poison tolerance are consistent with the interpretation that Pd nanoparticles are modified by carbonaceous deposits.

A Self‐Assembly Process for the Immobilization of N‐Modified Au Nanoparticles in Ordered Mesoporous Carbon with Large Pores

“…N‐containing species decompose to NO and NO 2 in the temperature range 200–400 °C (Figure ). The skeleton of the resins and PS blocks decomposes to CO, CO 2 , and H 2 O …”

Highly Selective Continuous Flow Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol in a Pt/SiO2 Coated Tube Reactor

“…Taylor flow with the alternating gas and liquid slugs was observed under all the conditions studied [73]. The average liquid residence time in the flow reactor was estimated by Equation (3).…”

“…Hydrogenation of cinnamaldehyde (CAL) is interesting not only due to wide applications of the valuable desired products [1][2][3][4][5][6], but also because it is a good model reaction to study structure-activity relationship of the catalysts [7,8]. The CAL molecule contains conjugated C=C and C=O bonds and an aromatic ring.…”

Improvement Effect of Ni to Pd-Ni/SBA-15 Catalyst for Selective Hydrogenation of Cinnamaldehyde to Hydrocinnamaldehyde

“…The 5.0 wt %Pd/MWCNT catalyst designed by Zhao et al gave 91.3% HALD selectivity at 98.6% CAL conversion under 40 bar H 2 pressure and 148 bar CO 2 pressure [59]. Chen et al reported 80% HALD selectivity with 100% CAL conversion over 3.0 wt % Pd/(SH)MSC catalyst [3]. 100% conversion of CAL and 97% HALD selectivity were obtained by using 0.7 wt %Pd/γ-Al 2 O 3 under 20 bar H 2 pressure in 3 h at 100 • C [60].…”

“…The selective catalytic hydrogenation of α, β-unsaturated carbonyl compounds to unsaturated alcohols or saturated aldehydes is an important step for the production of a great deal of chemicals, for instance, pharmaceuticals, spices, and fragrances [1][2][3]. Cinnamaldehyde (CAL) is a typical α, β-unsaturated aldehyde, which can produce various product distributions through its hydrogenation route (Scheme 1).…”