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Abstract: In heterogeneous catalysis, catalyst precursor activation and subsequent initial operation (‘conditioning’) under reaction conditions are often highly dynamic steps which are important in delivering effective catalyst performance over time scales of years. In many cases however, the phenomena occurring in both steps are often poorly understood. A novel approach to assess the conditioning step, comprising advanced catalyst testing methods in micro-reactors, catalyst characterisation and detailed kinetic and activity modelling techniques is demonstrated for a model system: the selective oxidation of n-butane to maleic anhydride (MA) using a pre-activated vanadium phosphorus oxide (VPO) catalyst. A transient kinetic model for the conditioning step is presented which describes the decline of population of active sites for three reaction pathways on the catalyst surface over time. Two reaction pathways, n-butane --> MA and n-butane --> COx decay similarly with time whilst a third, MA --> COx declines very sharply. The approach used provides important mechanistic information on catalyst reaction kinetics whilst also providing understanding the impact of reaction conditions on the catalyst during conditioning. [Copyright &y& Elsevier]

Abstract: The hybrid 2D compound [{Cu(bpy)}2(VO)3(PO4)2(HPO4)2]·2H2O (1), has been investigated due to its interesting magnetic and catalytic properties. Compound (1) acts as an efficient catalyst in the epoxidation of cyclohexene and styrene. The chemoselectivity towards the epoxidation of cyclohexene is notoriously higher than the one observed towards styrene. The bulk antiferromagnetic behaviour of [{Cu(bpy)}2(VO)3(PO4)2(HPO4)2]·2H2O (1) can be well described with a pentanuclear model, using five J values. Both antiferromagnetic and ferromagnetic interactions mediated by phosphate bridges are found to be present in this hybrid copper(II)–vanadium(IV) material. [Copyright &y& Elsevier]

This paper describes the development of a new technique, atomic beam deposition (ABD), for the fabrication of catalysts with different active sites capable of catalyzing different chemical reactions. Using ABD, submonolayer amounts of Te and Cu atoms were deposited on vanadyl pyrophosphate (VPO) catalyst particles, and precise non-steady-state kinetic characterization was performed using the temporal analysis of products (TAP) reactor immediately following deposition. Results from TAP Knudsen pulse response experiments determine if small changes in the metal surface composition would produce detectable changes in catalytic properties. Partial oxidation of 1-butene to furan was used as the test reaction. Furthermore, this paper also demonstrates the sensitivity of the TAP reactor by measuring oxygen uptake on a single 350 μm diameter polycrystalline Pt particle packed in a bed with 100,000 inert quartz particles of similar dimensions. The Pt experiments demonstrate the precise manipulation of surface oxygen content. [ABSTRACT FROM AUTHOR]