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Selective Hydrogenation of α,β‐Unsaturated Aldehydes and Ketones using Novel Manganese Oxide and Platinum Supported on Manganese Oxide Octahedral Molecular Sieves as Catalysts
Author(s) -
Manyar Haresh G.,
Yang Bo,
Daly Helen,
Moor Helen,
McMonagle Stephen,
Tao Yu,
Yadav Ganapati D.,
Goguet Alexandre,
Hu P.,
Hardacre Christopher
Publication year - 2013
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201200447
Subject(s) - catalysis , chemistry , dissociation (chemistry) , cinnamyl alcohol , molecular sieve , cinnamaldehyde , inorganic chemistry , manganese , adsorption , selectivity , platinum , hydrogen spillover , photochemistry , organic chemistry
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 CC or CO 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 H 2 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 H 2 O molecule. The theoretically calculated activation barrier was in good agreement with the experimentally determined value for the hydrogenation reactions, indicating that H 2 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 H 2 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.