The Comparative Effect of Particle Size and Support Acidity on Hydrogenation of Aromatic Ketones

Abstract

A comparative study was reported for both the effects of shape-confined cubic Pd particle size (8, 13, and 21 nm) and surface property of most commonly used supports (SiO 2 , Al 2 O 3 , and silica-alumina) on catalytic performance in the chemoselective hydrogenation of three model bio-oil chemicals (benzaldehyde, acetophenone, and butyrophenone). The results showed that the size of Pd particles could be more associated with the hydrogenation reaction than acidities of the supports. Smaller size of Pd particles, regardless of the type of the support, provided the higher catalytic performance. XPS data showed that the electronic properties of Pd particles were similar, therefore, the possible reasons were the higher fraction of Pd atoms on corner in smaller particles, the lower accessibility of hydrogen atom to reactant on bigger particles, and the more low-coordinated sites in the small-size particles due to the short-range ordering. In addition, Pd/SA catalysts (Brønsted acid sites on the support) showed the highest conversion and TOF compared to Pd/Al 2 O 3 and Pd/SiO 2 catalysts. This might be due to the enhanced the diffusion rates of the chemicals on the surface of the catalysts although they could not induce the ionic effect from the metal surface. Pd/ SiO 2 catalysts performed better than Pd/Al 2 O 3 catalysts (Lewis acid sites on the support). The flexible SiOH groups on surface made the easy interaction with the metal particles and promote the reaction.[a] Dr.

Recent developments of supported and magnetic nanocatalysts for organic transformations: an up-to-date review

“…The Pd/SiO 2 NPs (1.1 nm) exhibited 100% total conversion with the selectivity of 53.9% n-butane, 31.7% trans-2-butene, 2.5% 1-butene and 11.9% cis-2-butene, while the Pd/SiO 2 (1.9 nm) showed 19.1% total conversion to 0% n-butane, 31.6% trans-2-butene, 63.9% 1-butene and 4.4% cis-2-butene, and the last sample Pd/SiO 2 (2.7 nm) displayed 89.5% total conversion with 54.4% n-butane selectivity, 28.5% trans-2-butene, 7.0% 1-butene and 10.1% cis-2-butene. Kim et al (2019) fabricated Pd NPs using SiO 2 , Al 2 O 3 , and silica-alumina supporters in three different particle sizes of each as Pd/ SiO 2 -8, Pd/SiO 2 -13, Pd/SiO 2 -21, Pd/Al 2 O 3 -8, Pd/Al 2 O 3 -13, Pd/Al 2 O 3 -21 and Pd/SA-8, Pd/SA-13, Pd/SA-21 for the chemoselective hydrogenation of bio-oil chemicals; acetophenone (Aph), benzaldehyde (BA), and butyrophenone (Bph). The NPs in a small size exhibited higher conversion (100%) using Pd/SA-8 for BA in 3-h reaction time, while the Pd/SA-13 and Pd/SA-21 exhibited 65 and 50% conversions, respectively.…”

Ni@C Catalyzed Hydrogenation of Acetophenone to Phenylethanol under Industrial Mild Conditions in Flow Reactor

“…through heterogeneous catalysis is an important field in the industrial hydrogenation process 1 2-10 . As a valuable intermediate for the production of spices, edible flavors, and medicines, currently, the demand for the hydrogenated product of acetophenone, phenylethanol, has been large and increasing [11][12][13][14] . At present, most of the phenethyl alcohol in the industry is synthesized by chemical means using benzene or styrene.…”

Formation and Location of Pt Single Sites Induced by Pentacoordinated Al Species on Amorphous Silica–Alumina

“…The induced SMSI of metal active species on alumina were extensively studied by various techniques, such as X-ray photoelectron spectroscopy (XPS), , electron energy loss spectroscopy (EELS), X-ray adsorption spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with CO chemisorption. , In general, introducing SMSI could strongly influence the electronic properties of metal active sites. Chemoselective hydrogenation of unsaturated aldehydes and ketones into unsaturated alcohols is quite sensitive to changes in the electronic properties on metal active sites. − The chemoselective hydrogenation of acetophenone (Aph) is very promising in the production of phenylethanol for the perfume industry and ethylbenzene for the polymer and fuel industry, and thus, it is often utilized as a probe reaction to evaluate the effect of induced SMSI on the activity of supported metal catalysts.…”

“…As one of the most important alumina mixed oxides, amorphous silica–alumina (ASA) materials are interesting for the preparation of supported metal nanocatalysts but rarely for providing surface Al V sites . Recently, Al V -enriched ASAs were successfully synthesized with a large surface population of Al V sites (≤55%), − and thus, they are expected to be suitable supports for tailoring highly dispersed metal single sites on supports with SMSI.…”

“…The chemoselective hydrogenation of aromatic ketones is a structure-sensitive model reaction. ,, As reported in the literature, high-performance Pt catalysts for hydrogenation are often achieved with Pt particle sizes of 1–3 nm, and Aph, as the simplest aromatic ketone, is typically used to evaluate the chemoselectivity of supported metal catalysts in hydrogenation. The reaction was carried out in an autoclave with a hydrogen pressure of 3 bar and stirring at 30 °C.…”