Superior Performance of a Nanostructured Platinum Catalyst in Water: Hydrogenations of Alkenes, Aldehydes and Nitroaromatics

Abstract

The hydrogenations of > C=C < , > C=O and nitro groups in ArNO 2 , with a water-soluble, polymer [poly(diallyldimethylammonium chloride)] supported, platinum carbonyl cluster {[Pt 30 (CO) 60 ] 2À } derived catalyst 1, have been studied. The performance of 1 has been compared with that of two other platinum catalysts: catalyst 2 prepared by the hydrogen reduction of [PtCl 6 ] 2À supported on the same water-soluble polymer, and 3, a commercial platinum catalyst (5 % Pt on alumina). Our catalyst 1 has been found to be more active than 2 and 3, and by TEM it has been shown that the nanoparticles in 1 are much smaller than those in 2. In the hydrogenation of o-chloronitrobenzene both 1 and 2 were found to be more selective (no hydrodehalogenation) than 3. To evaluate the advantages of water as a solvent, comparative studies have been carried out in three different solvent systems: water, methanol and a 1:1 mixture of water and toluene. Hydrogenations in methanol have been found to be accompanied by induction times while no such induction time is observed in water. Both liquid (methyl pyruvate, benzaldehyde, safflower oil and styrene) and waterinsoluble solid nitroaromatics (o-and m-chloronitrobenzene and p-aminonitrobenzene) have been tested as substrates, and for all the substrates the activity in water was found to be higher.

Ru Nanoparticles Entrapped in Mesopolymers for Efficient Liquid-phase Hydrogenation of Unsaturated Compounds

“…At present, heterogeneous catalysts are frequently used in this kind of hydrogenation reaction owing to easy product separation and catalyst recycling. Many metals, such as Pt- [4][5][6][7][8][9], Ru- [5,[10][11][12][13][14][15], Au- [16], Pd- [5], Ir- [17], Co- [18] and Cu-based [19] catalysts, have been attempted in the heterogeneous hydrogenation of carbonyl compounds. Among these catalysts, Ru-based catalysts have been extensively studied.…”

Metal Catalyzed Electrochemical Synthesis of Hydrocarbons from Epitaxial Graphene

“…However, counter to what the literature suggests, 16 hydrogen content on average was shown to be higher in Au enhanced hydrogenation than Pt. This is most likely due to the fact that in most hydrogen catalysis reactions, H 2 -dissociation is the bottleneck, 13,14 a step we circumvent in this study by using free H + in aqueous state. Indeed, in reactions where H 2 dissociation has already occurred, Au has been shown to be an extremely effective catalyst for hydrogenation.…”

Pt–Pd bi-metal nanoparticles captured and stabilized by imine groups in a periodic mesoporous organosilica of SBA-15 for hydrogenation of nitrobenzene

“…Therefore, the design of a catalyst, which can work under mild reaction conditions and give high catalytic performances, should be very interesting [7][8][9][10]. Recently, supported nanoparticles of Pt, Pd, etc., with high surface-to-volume ratio compared to bulk catalytic materials, have been recognized as one of the most relevant catalysts for hydrogenation of nitrobenzene [11][12][13]. The precise control of the metal particles size, shape, composition and distribution become the key to achieve the high catalytic activity.…”