Pt‐WO_x/C Catalysts for α, β‐Unsaturated Aldehydes Hydrogenation: An NMR Study of the Effect of the Reactant Adsorption on Activity and Selectivity

Abstract

The selective hydrogenation of α,β‐unsaturated aldehydes is an ideal case for studying the structure‐activity relationships in heterogeneous catalysis. In particular, cinnamaldehyde can be used as probe molecule for revealing the competition between hydrogenation of C=C and C=O bond. Here, we investigated the effect of the modification of some Pt supported on carbon catalysts by WOx species in cinnamaldehyde hydrogenation, as WOx species are reported to increase the adsorption and activation of the C=O group of α, β‐unsaturated aldehydes. Classical techniques used for correlating the catalyst activity and the selectivity to the characteristic of the materials (XRD, HAADF‐STEM, XEDS mapping and XPS) have been coupled with NMR relaxometry, as innovative application, to disclose how the molecule approaches the catalyst surface. This indeed constitutes a crucial aspect that rule the catalytic activity. Therefore, an innovative, holistic approach has been used to consider the whole catalytic system.

Co–Ti Bimetallic Complex-Induced Phase Modulation of Co@Black TiO2 for Catalytic Hydrogenation of Cinnamaldehyde

“…Moreover, the η4 adsorption mode significantly aids this reaction, leading to the production of a mixture of HCAL, COL, and HCOL from CAL hydrogenation. , Therefore, catalyst modification is crucial to enhance selective CO bond hydrogenation for achieving exclusive selectivity to specific target products. Although there are reports of selective hydrogenation of CAL to a particular product with a noble/non-noble metal catalyst, controlling reaction efficiency and selectivity to a particular hydrogenated product in the presence of monometallic catalysts is a challenging task. − Among few notable contributions in this regard the Yang and Liu group has made significant contributions to this field by developing a metal–organic framework (MOF) based monometallic catalyst (Co) as well as a bimetallic catalyst (Co–Mo, Co–W, and Co–Pt) and achieved high selectivity toward COL under optimal reaction conditions. , However, achieving maximum activity and selectivity with these non-noble metal-based catalysts still remains a challenge. Next, to assess the catalytic activity of the synthesized materials, we selected cinnamaldehyde (CAL) as a model substrate for hydrogenation.…”

A Career in Catalysis: Laura Prati

“…At this moment, she is still working on this technique in parallel with the catalytic studies of new materials. Her latest results in this field are reported in a very recent publication on Pt-WO x supported on carbon catalysts, used for the hydrogenation of α,β-unsaturated aldehydes . Pt supported on carbon catalysts have been modified by WO x species, differentiating the sequential addition of W precursors and Pt.…”

“…Her latest results in this field are reported in a very recent publication on Pt-WO x supported on carbon catalysts, used for the hydrogenation of α,β-unsaturated aldehydes. 151 Pt supported on carbon catalysts have been modified by WO x species, differentiating the sequential addition of W precursors and Pt. Coupling Pt with WO x had a positive effect on the catalytic activity, which can be correlated to the W/Pt atomic ratio: the less active catalyst showed the lowest W/Pt ratio, while the most active catalyst showed the highest W/Pt atomic ratio.…”

Highly Efficient Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over CoRe/TiO2 Catalyst

“…It is widely believed that the introduction of a second metal is an effective way to enhance the catalytic properties of Co nanoparticles, although the catalytic mechanism of the bimetallic catalysts is far from clear [24]. Adjusting the metal-metal/metallic oxide interactions in the catalyst could improve the morphology of dispersed metals and result in electron transfer, thus enhancing the charge density of the active metal and affecting the adsorption/desorption of C=O or C=C bonds on CAL [5,25]. For instance, the CoGa 3 /MgO•Al 2 O 3 -LDH catalyst gave 96% COL selectivity in the hydrogenation of CAL at 100 • C and 20 bar H 2 for 8 h, which was significantly higher than the monometallic Co catalyst (42%) [26].…”