Andre C. van Veen

Oxidative Dehydrogenation of Ethane: Common Principles and Mechanistic Aspects

The increasing demand for light olefins and the changing nature of basic feedstock has stimulated substantial research activity into the development of new process routes. Steam cracking remains the most industrially relevant pathway, but other routes for light‐olefin production have emerged. Fluid catalytic cracking only produces ethene in minor concentrations. Challenged by marked catalyst deactivation, in contrast, catalytic dehydrogenation ethane up opens a more selective route to ethene. The oxidative dehydrogenation (ODH) of ethane, which couples the endothermic dehydration of ethane with the strongly exothermic oxidation of hydrogen, would potentially be the most attractive alternative route because it avoids the need for excessive internal heat input, but also consumes valuable hydrogen. In this Review, the current state of the ODH of ethane is compared with other routes for light‐olefin production, with a focus on the catalyst and reactor system variants. New catalyst systems and reactor designs have been developed to improve the industrial competitiveness of the ODH reaction of ethane. The current state of our fundamental understanding of the ODH of light alkanes, in particular in terms of catalyst and reactor development, is critically reviewed. The proposed mechanisms and the nature of the active site for the ODH reaction are described and discussed in detail for selected promising catalysts. The reported catalytic performance and the possible limitations of these ODH catalysts will be examined and the performance of the emerging approaches is compared to the currently practiced methods.

Studies on the performance stability of mixed conducting BSCFO membranes in medium temperature oxygen permeation

A permeation study using bare Ba0.5Sr0.5Co0.8Fe0.2Ox membranes shows that stable oxygen fluxes are only achieved when operating the membrane at temperatures higher than 1023 K and indicates therefore that short contact time membrane reactors will be most suitable for future upgrading of light hydrocarbons.

Oxidative Dehydrogenation of Ethane on Dynamically Rearranging Supported Chloride Catalysts

Ethane is oxidatively dehydrogenated with a selectivity up to 95% on catalysts comprising a mixed molten alkali chloride supported on a mildly redox-active Dy2O3-doped MgO. The reactive oxyanionic OCl(-) species acting as active sites are catalytically formed by oxidation of Cl(-) at the MgO surface. Under reaction conditions this site is regenerated by O2, dissolving first in the alkali chloride melt, and in the second step dissociating and replenishing the oxygen vacancies on MgO. The oxyanion reactively dehydrogenates ethane at the melt-gas phase interface with nearly ideal selectivity. Thus, the reaction is concluded to proceed via two coupled steps following a Mars-van-Krevelen-mechanism at the solid-liquid and gas-liquid interface. The dissociation of O2 and/or the oxidation of Cl(-) at the melt-solid interface is concluded to have the lowest forward rate constants. The compositions of the oxide core and the molten chloride shell control the catalytic activity via the redox potential of the metal oxide and of the OCl(-). Traces of water may be present in the molten chloride under reaction conditions, but the specific impact of this water is not obvious at present. The spatial separation of oxygen and ethane activation sites and the dynamic rearrangement of the surface anions and cations, preventing the exposure of coordinatively unsaturated cations, are concluded to be the origin of the surprisingly high olefin selectivity.

Novel preparation of BIMEVOX materials assisting in elementary step resolved investigations of the oxygen transfer at the surface

A novel preparation method of BIMEVOX materials involving the decomposition of a well dispersed cation gel is described, allowing a simple, rapid manufacturing of bismuth-vanadium oxide based membranes. A detailed investigation of the required oxidative decomposition and the sintering procedure was performed, indicating the conditions for a complete removal of carbon containing compounds and the formation of dense samples. Differently doped BIMEVOX materials were prepared and investigations on the interaction of gas-phase oxygen with the membrane material were carried out. For the first time, the oxygen transfer from the gas phase to the bulk was studied directly by the highly time resolved TAP transient technique.

Oxidative coupling of methane in a catalytic membrane reactor: impact of the catalystmembrane interaction on the reactor performance.

Results for the oxidative coupling of methane to higher hydrocarbons in dense membrane reactors with surface catalysts are reported. It is demonstrated that the concept is viable, but potential improvements are identified enhancing the activity of the oxidative coupling catalyst for highly permeable membranes.

BIOGO : contributing to the transformation of the petrochemical industry through advances in nanocatalysts and reactor design

*Corresponding author: Gunther Kolb, Decentralized and Mobile Energy Technology Department, Fraunhofer ICT-IMM, Carl-ZeissStraße 18-20, 55129 Mainz, Germany, E-mail: Gunther.Kolb@imm.fraunhofer.de Hannah Newton: C-Tech Innovation Ltd, Capenhurst Technology Park, Capenhurst, Chester CH1 6EH, UK Qi Wang and Smitha Sundaram: Department of Chemical Engineering and Chemistry, Eindhoven Technical University, Postbus 513, Eindhoven 5600MB, The Netherlands Andre van Veen: School of Engineering, University of Warwick, Coventry CV4 7AL, UK Stefan Kiesewalter: Strategic Management, Fraunhofer ICT-IMM, Carl-Zeiss-Straße 18-20, 55129 Mainz, Germany Project profile

Ex-situ and In-situ Analysis of MoVTeNb Oxide by Aberration-Corrected Scanning Transmission Electron Microscopy

Short chain olefins, especially ethylene and propylene are very important industrial raw materials and are of increasing demand worldwide. The abundance of C2-C3 light alkanes in shale gas makes production of these olefins from oxidative dehydrogenation (ODH) one of the most attractive alternatives to industrial processes [1]. Among all the catalysts for C2-C3 light alkane ODH reactions, the two-phase MoVTeNb oxide system has shown great promise [1]. Much attention has been devoted to the analysis of the crystallography structure of catalytic active M1 phase. However, the nature of the surfaces where the reactions take place and their roles in catalysis have not been resolved. Additionally, it has been reported that surfaces of the M1 phase undergo changes during ODH reactions, which would affect the catalytic activity of the system [2]. Therefore, it is also very important to perform the in situ experimental observations under relatively realistic conditions for a fundamental understanding of the outstanding catalytic performance of this material.