Heterogeneous catalysts—discovery and design

Abstract

Heterogeneous catalysis plays a key role in the manufacture of essential products in key areas of agriculture and pharmaceuticals, but also in the production of polymers and numerous essential materials. Our understanding of heterogeneous catalysts is advancing rapidly, especially by using the latest characterisation methods on these relatively complex effect materials. At the heart of these catalytic processes, both selective oxidation and hydrogenation play a key role. Both oxidation and hydrogenation exhibit similar requirements since often a partial reaction product is required, rather than the products of total hydrogenation or oxidation, in the latter case this being typically carbon dioxide and water. This Feature Article considers the approaches available for catalyst discovery and design for heterogeneous catalysts. Three catalysts are considered in detail, two exemplifying oxidation and the other selective hydrogenation. The design of vanadium phosphates for the selective oxidation of butane to maleic anhydride is described in terms of the search for advanced materials with superior activity. This is achieved through the synthesis of wholly amorphous vanadium phosphates. The design of supported gold and gold palladium alloy catalysts for the oxidation of carbon monoxide and the direct hydrogenation of oxygen to form hydrogen peroxide is described and the problems concerning selectivity control are discussed.

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

“…One of the important features of BET results was that the replacement of the 1-hexanol, 1-heptanol and 1-decanol by 1-pentanol, slightly reduced the surface area to 34.3, 19.7 and 24.8 m 2 g −1 , respectively. However, the surface area of the solvothermal catalyst was found to be significantly higher than that reported for the VPO catalyst prepared via hydrothermal [20,21], organic and dihydrate [16,[36][37][38] methods. As mentioned, the BET surface area value is in agreement with the crystallite size distribution and obviously, larger crystals display lower surface area.…”

Crossing the divide between homogeneous and heterogeneous catalysis in water oxidation

“…Phosphonate-derivatized catalysts and molecular assemblies provide a basis for sustained water oxidation on these surfaces in acidic solution but are unstable toward hydrolysis and loss from surfaces as the pH is increased. Here, we report enhanced surface binding stability of a phosphonate-derivatized water oxidation catalyst over a wide pH range (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) by atomic layer deposition of an overlayer of TiO 2 . Increased stability of surface binding, and the reactivity of the bound catalyst, provides a hybrid approach to heterogeneous catalysis combining the advantages of systematic modifications possible by chemical synthesis with heterogeneous reactivity.…”

“…Examples include the Haber-Bosch process, steam reforming, Ziegler-Natta polymerization, and hydrocarbon cracking (1)(2)(3)(4)(5)(6)(7)(8). Research in heterogeneous catalysis continues to flourish (9-15) but iterative design and modification are restricted by limitations in materials preparation and experimental access to surface mechanisms.…”

Hybrid Systems Biomolecule-Polymeric Nanoparticle: Synthesis, Properties and Biotechnological Applications

“…Environmental technologies also rely heavily on catalysts; the best known example being the catalytic converter in the exhaust of every car. It is estimated that more than 20% of the gross national product (GNP) of industrial countries relies in one way or another on catalysis [57]. In heterogeneous catalysis, the reacting molecules adsorb on the catalytically active solid surface.…”