Selective Hydrogenation of α,β‐Unsaturated Aldehydes and Ketones using Novel Manganese Oxide and Platinum Supported on Manganese Oxide Octahedral Molecular Sieves as Catalysts

Abstract

The selective hydrogenation of α,β‐unsaturated aldehydes and ketones has been studied using ketoisophorone and cinnamaldehyde as model substrates using manganese oxide octahedral molecular sieve (OMS‐2) based catalysts. For the first time, OMS‐2 has been shown to be an efficient and selective hydrogenation catalyst. High selectivities for either the CC or CO double bond at ≈100 % conversion were achieved by using OMS‐2 and platinum supported on OMS‐2 catalysts. Density functional theory (DFT) calculations showed that the dissociation of H2 on OMS‐2 was water assisted and occurred on the surface Mn of OMS‐2(0 0 1) that had been modified by an adsorbed H2O molecule. The theoretically calculated activation barrier was in good agreement with the experimentally determined value for the hydrogenation reactions, indicating that H2 dissociation on OMS‐2 is likely to be the rate‐determining step. A significant increase in the rate of reaction was observed in the presence of Pt as a result of the enhancement of H2 dissociative adsorption and subsequent reaction on the Pt or spillover of the hydrogen to the OMS‐2 support. The relative adsorption strengths of ketoisophorone and cinnamaldehyde on the OMS‐2 support compared with the Pt were found to determine the product selectivity.

Platinum nanocrystals supported on CoAl mixed metal oxide nanosheets derived from layered double hydroxides as catalysts for selective hydrogenation of cinnamaldehyde

“…Selective hydrogenation of a,b-unsaturated aldehydes at the carbonyl (C@O) and olefinic (C@C) groups is highly desirable in the fine chemical industry, because most of their products are important intermediates for the synthesis of many chemicals [1]. Cinnamaldehyde (CAL) is a particularly important a,bunsaturated aldehyde, since its partial hydrogenation products are important intermediates in the manufacture of chemicals (particularly perfumes, flavors, and pharmaceuticals) [2,3].…”

High energy resolution fluorescence detection XANES – an in situ method to study the interaction of adsorbed molecules with metal catalysts in the liquid phase

“…It should be noted that the solvent 35 effect is not included explicitly in this system. In our previous work 8 it has already been demonstrated that, the chemistry including the selectivity can be adequately using this approach. From Figure 2, it can be seen that the adsorption energies on both Pt(111) and Pt(211) for KIP are significantly lower than those found for CIN and the adsorption energy for KIP on 50 OMS-2 is comparable with that on the Pt.…”

“…8 In the case of KIP, 98% selectivity for 65 the selective reduction of the C=C bond occurred resulting in the production of (6R)-2,2,6-trimethylcyclohexane-1,4-dione (levodione) at 100% conversion. OMS-2 was also found to be active for the same hydrogenation and also formed levodione selectively (97%), albeit at a lower reaction rate.…”

An Effective Pt-Cu/SiO2 Catalyst for the Selective Hydrogenation of Cinnamaldehyde

“…The unique advantage of such catalysts is that activity and selectivity can be tuned by controlling the size, shape, and surface species of Pt particles [1,[13][14][15]. In fact, many methods have been developed to enhance the performance of Pt-based catalyst, such as investigating novel support and promoter [15][16][17][18][19]. In our previous works, it was found that graphenesupported Pt catalysts showed high selectivity to COL [13]; and the activity and selectivity of Pt/carbon nanosheets (CNS) catalysts increased with the rise of the graphitization degree of CNS [20].…”