Recent Developments of Heterogeneous Catalysts for Selective Hydrogenation of Unsaturated Carbonyl Compounds to Unsaturated Alcohols

Abstract

Development of heterogeneous catalysts which can achieve both high activity and high selectivity requires establishment of sophisticated and uniform active sites on the surface of solid materials, but formation of uniform active sites is difficult in heterogeneous catalysts because of the nonuniformity of heterogeneous catalysts. Selective hydrogenation of the carbonyl group of unsaturated carbonyl compounds is particularly difficult because hydrogenation of the olefin group is thermodynamically and kinetically preferable to that of the carbonyl groups. Therefore, various heterogeneous catalyst systems have been developed to achieve high selectivity. Recently developed effective heterogeneous catalysts for the selective hydrogenation of unsaturated carbonyl compounds such as unsaturated aldehydes and unsaturated ketones to the corresponding unsaturated alcohols using H2 as a reducing agent are reviewed. Model reactions include liquid-phase selective hydrogenation of crotonaldehyde and liquid-phase selective hydrogenation of benzylideneacetone using a batch reactor, and gas-phase selective hydrogenation of crotonaldehyde with a fixed-bed reactor. Particularly, this review mainly covers metal oxide-or metal cation-modified noble metal catalysts.

Aqueous phase hydrogenation of furfural on Ni/TiO2 catalysts: nature of the support phase steers the product selectivity

“…Noble metals from the Pt group and non-noble metals like Ni, Cu, and Co as active phases have been extensively studied to improve the activity towards selective/partial hydrogenation of unsaturated organic compounds. 6,7 Furfural (furan-2carbaldehyde) has been identied as one of the key platform molecules, which is derived from pentosan rich agriculture residues like oats hull, corncobs, bagasse, rice husk, cotton husk, etc., by hydrolysis and dehydration processes. 8 It can be transformed into a wide variety of highly useful chemical intermediates, such as furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, cyclopentanone, cyclopentanol, pentanediols, etc., through hydrogenation, hydrodeoxygenation, hydrolysis, and rearrangement reactions.…”

“…Noble metals from the Pt group and non-noble metals like Ni, Cu, and Co as active phases have been extensively studied to improve the activity towards selective/partial hydrogenation of unsaturated organic compounds. 6,7 Furfural (furan-2-carbaldehyde) has been identified as one of the key platform molecules, which is derived from pentosan rich agriculture residues like oats hull, corncobs, bagasse, rice husk, cotton husk, etc. , by hydrolysis and dehydration processes.…”

Highly Efficient Ir–CoOx Hybrid Nanostructures for the Selective Hydrogenation of Furfural to Furfuryl Alcohol

“…Alternatively, literature has reported Pt, ,, Ir, , Co, and Cu for the hydrogenation of furfural. Among various systems, Ir-based catalysts are recognized as efficient catalysts for the hydrogenation of CO bonds relative to CC bonds due to their larger band widths of d bands, but their hydrogenation activities are relatively low under mild reaction conditions. ,− Various supports, − alloys such as nickel–iridium alloy with highly active isolated Ni atom, and strong metal–support interaction , have been employed to enhance the catalytic performance of Ir-based catalysts while introducing proper metal oxides ,− is one of the most efficient strategies. For example, Ir–ReO x /SiO 2 catalysts show superior selectivity to furfuryl alcohol (>99%) relative to the monometallic Ir catalysts.…”

Effects of Sn<i>_x</i>Pt<i>_y</i> Alloy Structures on the Performance of SnPt Catalysts for the Selective Hydrogenation of Unsaturated Aldehydes to Unsaturated Alcohols

“…The function of the Sn component is not yet fully understood, but the improvement in catalytic selectivity achieved by inclusion of Sn has been ascribed to two effects. First, ionic Sn species (Sn 2 or Sn 4 ) are believed to interact with the carbonyl oxygen of unsaturated aldehydes, resulting in activation of the C O group and acceleration of the hydrogenation reaction 7),11),13),14),17),19), 21) . Second, metallic Sn is thought to dilute the Pt ensembles and form Sn _ Pt alloys 7),13) 15),17),20), 22) .…”