Enhancement of catalytic activity in dehydrogenation ofn-dodecane over nano-structured Pt-Sn/SBA-16 catalysts by microwave drying

In the present investigation, experimental results from a study of cubic SBA-16-supported Pt-Sn bimetallic catalysts used to investigate dehydrogenation ofn-dodecane to 1-dodecene are presented. Pt (1 wt%)-Sn (1 wt%)/SBA-16 catalyst is synthesized using a simple co-impregnation (CI) method. Further, the impregnated catalysts are dried separately using microwave drying (MW-D) and conventional electrical drying (CE-D) techniques. The microwave-mediated drying of Pt (1%)-Sn (1%)/SBA-16 shows a better catalytic performance and time-on-stream activity for the target reaction.     

Consideration of some sampling problems in the on-line analysis of batch processes by low-field NMR spectrometry

A low-field medium-resolution NMR spectrometer, with an operating frequency of 29 MHz for 1H, has been assessed for on-line process analysis. A flow cell that incorporates a pre-magnetisation region has been developed to minimise the decrease in the signal owing to incomplete polarisation effects. The homogeneous esterification reaction of crotonic acid and 2-butanol was monitored using a simple sampling loop; it was possible to monitor the progression of the reaction through changes in CH signal areas of butanol and butyl crotonate. On-line analysis of heterogeneous water-toluene mixtures proved more challenging and a fast sampling loop system was devised for use with a 5 L reactor. The fast sampling loop operated at a flow rate of 8 L min(-1) and a secondary sampling loop was used to pass a sub-sample through the NMR analyser at a slower (mL min(-1)) rate. It was shown that even with super-isokinetic sampling conditions, unrepresentative sampling could occur owing to inadequate mixing in the reactor. However, it was still possible to relate the 1H NMR signal obtained at a flow rate of 60 mL min(-1) to the composition of the reactor contents.     

Oxidation of ethylenediaminetetraacetate by tris(diimine) iron(III) complexes and the dodecatungstocobaltate(III) ion: a comparative kinetic and mechanistic study

Summary The stoichiometry and kinetics of the oxidation of ethyl-enediaminetetraacetate by [Fe(phen)₃]³⁺, [Fe(bipy)₃]³⁺ and [Co^IIIW₁₂O₄₀]⁵⁻ were studied in aqueous HClO₄. Reaction rates were first order with respect to the oxidants and the reductant, and the dependence of the second order rate constant k ₂ on [H⁺] is given by k ₂ = a + b[H^{+ −}. The primary products were CO₂, CH₂O and (CH₂NH₂)₂. Schuster treatment is employed to show that the reactions occur by the outersphere mechanism.     

Oxidation of N-(2-hydroxyethyl)ethylenediamine triacetate by tris(polypyridy)iron(III) complexes and the dodecatungstocobaltate(III) ion

Summary The stoichiometry, kinetics and mechanism of oxidation of N-(2-hydroxyethyl)ethylenediamine triacetate by K₅Co^IIIW₁₂O₄₀, Fe(phen) _inf3 ^sup3+ and Fe(bipy) _inf3 ^sup3+ have been studied. Each reaction is first order with respect to the oxidant and the reductant, but retarded by [H⁺] in the 0.20–1.60 mol dm ^–3 range. Simple electron exchanges are thought to occur, leading to the decarboxylation of the substrate.