Poly[aqua­(μ5-2-oxido-4-sulfonato­benzoato)lanthanum(III)]

The title compound, [La(C7H3O6S)(H2O)]n, forms a three-dimensional framework in which the asymmetric unit contains one LaIII atom, one 5-sulfosalicylate (2-oxido-4-sulfonatobenzoate) ligand and one coordinated water mol­ecule. The LaIII atom is coordinated by nine O atoms from three carboxyl­ate, three sulfonate and two hydroxyl groups, and one water mol­ecule, forming a distorted trigonal-prismatic square-face tricapped geometry

Identification of kinetic models of methanol oxidation on silver in the presence of uncertain catalyst behavior

Catalytic oxidation of methanol to formaldehyde is an important industrial process due to the value of formaldehyde either as a final product or as a precursor of numerous chemicals. The study of kinetics in this system is hindered by sources of uncertainty that are inherently associated to the nature and state of the catalyst (e.g., uncertain reactivity level, deactivation phenomena), the measurement system and the structure of the kinetic model equations. In this work, a simplified kinetic model is identified from data collected from continuous flow microreactor systems where catalysts with assorted levels of reactivity are employed. Tailored model-based data mining methods are proposed and applied for the effective estimation of the kinetic parameters and for identifying robust experimental conditions to be exploited for the kinetic characterization of catalysts with different reactivity, whose kinetic behavior is yet to be investigated

Rapid Screening of Kinetic Models for Methane Total Oxidation using an Automated Gas Phase Catalytic Microreactor Platform

An automated flow micropacked bed catalytic reactor platform was developed to conduct pre-planned experiments for rapid screening of kinetic models. The microreactor was fabricated using photolithography and deep reactive ion etching of a silicon wafer, with a reaction channel width and depth of 2 mm and 420 μm respectively. It was packed with ca. 10 mg of 5 wt. % Pd/Al2O3 catalyst to perform methane combustion, which was the selected reaction to test the developed platform. The experimental system was monitored and controlled by LabVIEW to which Python scripts for online design of experiments and data analysis were integrated. Within each experimental campaign, the platform automatically adjusted the experimental conditions, and the analysis of the product stream was conducted by online gas chromatography. The experimental platform demonstrated the capability of identifying the most probable kinetic models amidst potential models within two days

An effective approach for mining mobile user habits.

ABSTRACT The user interaction with the mobile device plays an important role in user habit understanding. In this paper, we propose to mine the associations between user interactions and contexts captured by mobile devices, or behavior patterns for short, from context logs to characterize the habits of mobile users. The extensive experiments on the collected real life data clearly validate the ability of our approach for mining effective behavior patterns

Hydrodynamic effects on three phase micro-packed bed reactor performance – Gold–palladium catalysed benzyl alcohol oxidation

The hydrodynamics of a three-phase micro-packed bed reactor and its effect on catalysed benzyl alcohol oxidation with pure oxygen were studied in a silicon–glass microstructured reactor. The microreactor was operated at 120 °C and 1 barg and contained a channel with a 300 μm×600 μm cross-section, packed with 1 wt% Au–Pd/TiO2 catalyst, 65 μm in average diameter. Improvements in the conversion of benzyl alcohol and selectivity to benzaldehyde were observed with increasing gas-to-liquid ratio, which coincided with a change in the flow pattern from a liquid-dominated slug to a gas-continuous flow regime. The observed enhancement is attributed to improved external mass transfer, associated with an increase in the gas–liquid interfacial area and reduction in the liquid film thickness that occur with gradual changes in the flow pattern. A maximum selectivity of 93% to benzaldehyde was obtained under partial wetting – which introduced the added benefit of direct gas–solid mass transfer – outperforming the selectivity in a conventional glass stirred reactor. However, this was at the expense of a reduction in the conversion. A response surface model was developed and then used to predict optimal operating conditions for maximum benzaldehyde yield, which were in the gas-continuous flow regime. This corresponded to relatively high gas flow rate in conjunction with moderate liquid flow rate, ensuring sufficient catalyst wetting with a thin film to reduce transport resistance

A micropacked-bed multi-reactor system with in situ raman analysis for catalyst evaluation

AbstractA micropacked-bed multi-reactor platform with integrated portable Raman spectrometer is presented for fast evaluation of catalyst activity and stability for gas/liquid/solid reactions. The silicon-glass microreactor was designed and fabricated so that pockets containing the liquid reaction mixture were created after each packed bed, into which the laser could be directed for Raman spectral acquisition. Using the oxidation of benzyl alcohol as a model reaction, the Raman spectrum was found to be affected both by temperature and by the composition of the multiphase reaction mixture which was related to the reaction conversion. These effects were accounted for by calibrating the Raman spectra at the reaction temperature using mixtures produced by the reactors that were analysed independently by gas chromatography. Fourteen catalysts containing different combinations of Au, Pd and Pt supported on TiO2 prepared by sol-immobilisation (SI) and standard impregnation (SImp) techniques were tested. The results showed that the activity of the catalysts prepared by SI was overall higher than those prepared by SImp, while the activity sequence followed the same pattern: Pd>AuPd>AuPdPt>PdPt>(Au, Pt, AuPt). The Pd and AuPd catalysts from both SI and SImp were stable in 5-h testing, however, for the PdPt and AuPdPt catalysts prepared by SI deactivation was observed

Three step synthesis of benzylacetone and 4-(4-methoxyphenyl)butan-2-one in flow using micropacked bed reactors

The synthesis of benzylacetone from benzyl alcohol and of 4-(4-methoxyphenyl)butan-2-one from 4-methoxybenzyl alcohol, which were previously performed in a batch cascade, were successfully performed in a telescoped flow system consisting of three micropacked bed reactors and a tube-in-tube membrane to remove oxygen. The system consisted of approximately 10 mg of 1 wt% AuPd/TiO2 catalyst for oxidation, 150-250 mg of anatase TiO2 for C-C coupling and 10 mg of 1 wt% Pt/TiO2 for reduction, operating at 115 °C, 130 °C and 120 °C respectively. Oxygen and hydrogen flowrates were 2 and 1.5 NmL/min and alcohol solution inlet flowrates were 10-80 µL/min, while the system operated at a back pressure of 5 barg. This system achieved significantly increased yields of benzylacetone compared to the batch cascade (56% compared to 8%) and slightly increased yields of 4-(4-methoxyphenyl)butan-2-one (48% compared to 41% when using the same catalyst supports). The major advantage of the telescoped flow system was the ability to separate the three reactions, so that each reaction could have its own catalyst and operating conditions, which led to significant process intensification

Solvent-free aerobic oxidation of alcohols using supported gold palladium nanoalloys prepared by a modified impregnation method

The synthesis of stable, supported, bimetallic nanoalloys with controlled size, morphology and composition is of great practical importance. Compared to their monometallic analogues, such materials exhibit remarkable enhancement in functional properties, which can be exploited in various fields including catalysis. Recently, we have reported a simple excess anion modification of the impregnation method to prepare supported gold–palladium catalysts which gives very good control over the particle sizes and the composition without using any stabilizer ligands in the preparation. Here, we report the results from a comparative study of using this modified impregnation catalyst for the solvent-free aerobic oxidation of alcohols in two different reactors: a glass stirred reactor and a micro packed bed reactor under batch and continuous mode respectively. These modified impregnation catalysts are exceptionally active and more importantly, when tested in a micro packed bed reactor under flow conditions, are observed to be stable for several days without any sign of deactivation in contrast to the same catalyst prepared by the sol immobilization method in the presence of stabilizer ligands which showed a 3–5% decrease in conversion over 10–12 h

A Novel Approach for Measuring Gas Solubility in Liquids Using a Tube-in-Tube Membrane Contactor

© 2017 The Authors. Chemical Engineering & Technology is published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim A novel approach using a semipermeable Teflon AF-2400 tube-in-tube membrane contactor was developed for the measurement of gas solubility in organic solvents. This membrane ensures gas saturation of liquids in continuous flow at a specific pressure and temperature. After liquid decompression, the amount of gas outgassed was measured with a bubble meter and used for solubility calculation. The proposed method was applied to the measurement of oxygen solubility in toluene and benzyl alcohol. Validation experiments were initially performed by comparing the obtained oxygen solubility in toluene with literature data. With higher temperature, the solubility of oxygen in benzyl alcohol was found to increase, indicating that the oxygen-dissolving process is endothermic. Finally, an empirical correlation of Henry's law constant as a function of temperature was determined.status: publishe