Reforming Catalysts

Abstract

Steam and dry reforming of hydrocarbons (e.g., methane, ethane or propane), alcohols (e.g., methanol, ethanol or glycerol) or bio-compounds is one of the most promising and effective routes to enhanced hydrogen production and for the production of synthesis gas likewise. For steam reforming, the most crucial step of this reaction is efficient water activation, which is a necessary prerequisite for both a high CO 2 selectivity and a high associated hydrogen yield. The reactions have been studied on a variety of different catalytic surfaces, encompassing oxides, supported metal-oxide systems or (supported) intermetallic compounds. The controllable steering of product selectivity is thereby an obvious key criterion for technical usage. For methanol steam reforming, the key targets-apart from pronounced CO 2 selectivity-are, thus, a maximum hydrogen yield and a low CO content in the reformate to realize the efficient on-board production of clean hydrogen in, e.g., automotive applications. Given the structural and chemical complexity and diversity of the materials used, the question about the common elementary reaction steps of the steam reforming reaction is imperative. For structurally more complex materials, such as the recently put-forward oxide-supported Pd-based intermetallic phases, a bifunctional synergism is usually assumed, where the participating catalytic entities (or the in situ created interface) synergistically act in the catalytic reaction. In this special issue, we show the complexity of the interplay between the synthesis and performance of novel materials in a variety of technologically important reforming reactions. To do the complexity justice, the materials discussed particularly reflect the importance of accurate synthesis procedures to prospective catalytic materials.Two review reports by Debek et al.[1] and Du et al.[2] deal with the reforming properties of hydrotalcite-derived materials in methane dry reforming and methane and ethanol steam reforming, respectively. The effects of catalyst preparation and regeneration, thermal treatment processes, composite design, catalyst deactivation and the addition of dopants are addressed in both reviews for Ni-based hydrotalcite materials.The role of metal-oxide and oxide-oxide composite materials as well as intermetallic and alloy catalysts in reforming of hydrocarbons, alcohols and bio-compounds (acetone, furfural and glucose) forms the core of the eight regular articles that are part of this special issue. Ethanol steam reforming over Sc 2 O 3 -doped Co-ZnO catalysts is adressed by Liang et al. Sc 2 O 3 doping is shown to enhance catalytic performance, exceeding that of Sc 2 O 3 -free Co-ZnO considerably [3]. The improved catalytic activity is ascribed to an increased electronic interaction between Co and ZnO, leading to elevating the reduction temperature of Co oxides, increasing the disperison of ionic Co species and improved sintering behavior of active Co species. Cheng et al. focus on the role of auto-reduced Ni-Al 2 O 3 catalysts in steam refo...