pinecone/core-2020-05-10-deduplication huggingface dataset:
Recoverable Dendritic Phase-Transfer Catalysts that Contain (+)-Cinchonine-Derived Ammonium Salts

Four new phosphorus dendrimeric phase-transfer catalysts are prepared that contain 12 (+)-cinchoninium salts on the surface obtained by the quaternisation of the quinuclidinic N atom. The asymmetric alkylation of a glycinate Schiff base with benzyl bromide is used as a benchmark reaction, and the dendrimeric catalyst that contains an allyl group on the O-9 hydroxy group of the cinchonine units is the most active. The recovery and reuse of the catalyst are possible for five consecutive runs without loss of activity and with only a slight decrease in enantioselectivity. If other electrophiles are used, substituted benzyl bromides give better results than other activated alkyl bromides to afford the corresponding R amino acid derivatives. A comparison of these results with those reported previously for similar cinchoninium salts shows that dendrimers could be a better support than other polymers for this type of organocatalysis.This research was supported by the Ministerio de Ciencia e Innovación (CTQ2011-2264 and Consolider Ingenio 2010 CSD2007-00006), Ministerio de Economía y Competitividad (CTQ 2014–53662-P and CTQ2014-51912-REDC) FEDER and the DURSI-Generalitat de Catalunya (2014SGR-1105). We thank the Consolider Ingenio Program for the contract of J.R. and UAB for the grant of J.J.J
Rapid-Scan Operando Infrared Spectroscopy

Novel methodology, referred to as rapid-scan operando, has been demonstrated to be a highly powerful tool for studying reaction mechanisms in heterogeneous catalysis, because it combines rapid scan for IR monitoring in the milliseconds time frame and operando methodology. As proof of concept, the NOx–CO and NOx–H2 reactions were studied as model catalyzed reactions with practical interest for removal of NOx in diesel exhausts. Rapid-scan operando experiments confirmed state-of-the-art knowledge concerning the reaction mechanisms and, more importantly, allowed us to elucidate, for the first time, the different roles of the surface hydroxy groups depending on the reductant used (CO or H2). Moreover, this new tool was used to distinguish the behavior of carbonates and nitrites under reaction conditions that could not be monitored by conventional IR spectroscopy approaches owing to overlap of their absorbance bands.Financial support from Generalitat Valenciana (Project PROMETEOII/2014/010 and grant BEST/2014/250), Spanish Ministry of Economy and Competitiveness (Projects CTQ2012–30703 and MAT2014–61992-EXP, and grant PRX14/00249), and the European Union (FEDER funding)
Ethanol to 1,3-butadiene conversion using ZrZn-containing MgO-SiO2 systems prepared by co-precipitation and effect of catalyst acidity modification

The conversion of ethanol to 1,3-butadiene (1,3-BD) has been investigated over ZrO2 and ZnO containing magnesia silica oxides prepared by co-precipitation method at different Mg-to-Si molar ratios. The effect of reaction temperature and ethanol flow rate was investigated. The catalyst acidity was modified through the addition of alkali metals (Na, K and Li) to the final materials. Catalysts were characterised by nitrogen physisorption analysis, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray, temperature programmed desorption of ammonia, infrared spectroscopy and 29Si/(7Li) NMR spectroscopy. The catalytic results showed that the controlled reduction of catalyst acidity allows suppressing of ethanol dehydration, whilst increasing 1,3-BD selectivity. The best catalytic performance achieved 72 mol % for the combined 1,3-BD and acetaldehyde selectivit
Tetrathiafulvalene–7,7,8,8-tetracyanoquinodimethane and tetrathiafulvalene–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane organic charge-transfer complexes: Reusable catalysts for electron-transfer reactions

The application of organic charge-transfer complexes such as TTF-TCNQ (TTF=tetrathiafulvalene, TCNQ=7,7,8,8-tetracyanoquinodimethane) is well known in the area of organic electronics. However, the applicability of this material and its derivatives has not been explored for catalytic reactions. Herein, we report on the catalytic properties of both TTF-TCNQ and the significantly less-known fluorinated analogue TTF-TCNQF<sub>4</sub> (TCNQF<sub>4</sub>=2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane). The model reaction of ferricyanide ion reduction by thiosulfate ions was chosen, for which it was found that both materials were indeed catalytically active. Significantly, the fluorinated TCNQF<sub>4</sub> analogue showed considerably higher catalytic activity than TTF-TCNQ. In addition, TTF-TCNQF<sub>4</sub> was found to be highly stable under the catalytic conditions and could be recovered and reused without any loss in performance for at least 10 catalytic cycles. This work opens up new avenues for investigating these types of materials for catalytic reactions
Future challenges in heterogeneous catalysis: understanding catalysts under dynamic reaction conditions

In the future, (electro-) chemical catalysts will have to be more tolerant towards a varying supply of energy and raw materials. This is mainly due to the fluctuating nature of renewable ener-gies. For example, power-to-chemical processes require a shift from steady-state operation towards operation under dynamic reaction conditions. This brings along a number of demands for the design of both catalysts and reactors, because it is well-known that the structure of catalysts is very dynamic. However, in-depth studies of catalysts and catalytic reactors under such transient conditions have only started recently. This requires studies and advances in the fields of 1) operando spectroscopy including time-resolved methods, 2) theory with predictive quality, 3) kinetic modelling, 4) design of catalysts by appropriate preparation concepts, and 5) novel/modular reactor designs. An intensive exchange between these scientific disciplines will enable a substantial gain of fundamental knowledge which is urgently required. This concept article highlights recent developments, challenges, and future directions for understanding catalysts under dynamic reaction conditions.DFG, GR 3987/2-
One-pot Synthesis of 1,3-Butadiene and 1,6-Hexanediol Derivatives from Cyclopentadiene (CPD) via Tandem Olefin Metathesis Reactions

A novel tandem reaction of cyclopentadiene (CPD) leading\ud
to high value linear chemicals via ruthenium catalyzed ring opening cross metathesis (ROCM), followed by cross metathesis (CM) is reported. The ROCM of cyclopentadiene (CPD) with ethylene using commercially available 2nd gen. Grubbs metathesis catalysts (1‐G2) gives 1,3‐butadiene (BD) and 1,4‐pentadiene (2) (and 1,4‐cyclohexadiene (3)) with reasonable yields (up to 24 % (BD) and 67 % (2+3) at 73 % CPD conversion) at 1–5 mol % catalyst loading in toluene solution (5 V% CPD, 10 bar, RT) in an equilibrium reaction. The ROCM of CPD with cis‐butene diol diacetate (4) using 1.00 ‐ 0.05 mol % of 3rd gen. Grubbs (1‐G3) or 2nd gen. Hoveyda‐Grubbs (1‐HG2) catalysts loading gives hexa‐2,4‐diene‐1,6‐diyl diacetate (5), which is a precursor of 1,6‐hexanediol (an intermediate in polyurethane, polyester and polyol synthesis) and hepta‐2,5‐diene‐1,7‐diyl diacetate (6) in good yield (up to 68 % or TON: 1180). Thus, convenient and selective synthetic procedures are revealed by ROCM of CPD with ethylene and 4 leading to BD and 1,6‐hexanediol precursor, respectively, as key components of commercial intermediates of high‐performance materials
Ligand Migration from Cluster to Support : A Crucial Factor for Catalysis by Thiolate-protected Gold Clusters

Thiolate protected metal clusters are valuable precursors for the design of tailored nanosized catalysts. Their performance can be tuned precisely at atomic level, e. g. by the configuration/type of ligands or by partial/complete removal of the ligand shell through controlled pre-treatment steps. However, the interaction between the ligand shell and the oxide support, as well as ligand removal by oxidative pre-treatment, are still poorly understood. Typically, it was assumed that the thiolate ligands are simply converted into SO, CO and HO. Herein, we report the first detailed observation of sulfur ligand migration from Au to the oxide support upon deposition and oxidative pre-treatment, employing mainly S K-edge XANES. Consequently, thiolate ligand migration not only produces clean Au cluster surfaces but also the surrounding oxide support is modified by sulfur-containing species, with pronounced effects on catalytic properties
Catalytic Upgrading of Biomass Model Compounds: Novel Approaches and Lessons Learnt from Traditional Hydrodeoxygenation – a Review

Catalytic hydrodeoxygenation (HDO) is a fundamental process for bio‐resources upgrading to produce transportation fuels or added value chemicals. The bottleneck of this technology to be implemented at commercial scale is its dependence on high pressure hydrogen, an expensive resource which utilization also poses safety concerns. In this scenario, the development of hydrogen‐free alternatives to facilitate oxygen removal in biomass derived compounds is a major challenge for catalysis science but at the same time it could revolutionize biomass processing technologies. In this review we have analysed several novel approaches, including catalytic transfer hydrogenation (CTH), combined reforming and hydrodeoxygenation, metal hydrolysis and subsequent hydrodeoxygenation along with non‐thermal plasma (NTP) to avoid the supply of external H2. The knowledge accumulated from traditional HDO sets the grounds for catalysts and processes development among the hydrogen alternatives. In this sense, mechanistic aspects for HDO and the proposed alternatives are carefully analysed in this work. Biomass model compounds are selected aiming to provide an in‐depth description of the different processes and stablish solid correlations catalysts composition‐catalytic performance which can be further extrapolated to more complex biomass feedstocks. Moreover, the current challenges and research trends of novel hydrodeoxygenation strategies are also presented aiming to spark inspiration among the broad community of scientists working towards a low carbon society where bio‐resources will play a major role.Financial support for this work was provided by the Department of Chemical and Process Engineering of the University of Surrey and the EPSRC grants EP/J020184/2 and EP/R512904/1 as well as the Royal Society Research Grant RSGR1180353. Authors would also like to acknowledge the Ministerio de Economía, Industriay Competitividad of Spain (Project MAT2013‐45008‐P) and the Chinese Scholarship Council (CSC). LPP also thanks Comunitat Valenciana for her postdoctoral fellow (APOSTD2017)
Career construction counseling with a mid-career black man

Career construction counseling for a mid-career Black man is
examined. The author implemented a case study design and
purposively selected the participant. The intervention and
follow-up occurred over a period of 21 months, and the
Career Construction Interview (CCI; Savickas, 2011a) was
used to gather data. Savickas‟s 8-step strategy was followed
to complete the participant‟s life portrait. After the
intervention, the participant demonstrated an improved sense
of self and willingness to deal more adaptively with careerlife-
related challenges. More research is needed to determine
the long-term effects of this kind of intervention and to show
its applicability in group contexts.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2161-00452018-03-31hb2016Educational Psycholog
Particle-by-Particle Reconstruction of Ultrafiltration Cakes in 3D from Binarized TEM Images

Transmission electron microscopy (TEM) imaging is one of the few techniques available for direct observation of the microstructure of ultrafiltration cakes. TEM images yield local microstructural information in the form of two-dimensional grayscale images of slices a few particle diameters in thickness. This work presents an innovative particle-by-particle reconstruction scheme for simulating ultrafiltration cake microstructure in three dimensions from TEM images. The scheme uses binarized TEM images, thereby permitting use of lesser-quality images. It is able to account for short- and long-range order within ultrafiltration cake structure by matching the morphology of simulated and measured microstructures at a number of resolutions and scales identifiable within the observed microstructure. In the end, simulated microstructures are intended for improving our understanding of the relationships between cake morphology, ultrafiltration performance, and operating conditions
Removal of Cr(VI) from aqueous solutions by a bacterial biofilm supported on zeolite : optimisation of the operational conditions and scale-up of the bioreactor

The aim of this study was to investigate the feasibility of a bioreactor system and its scale-up to remove Cr(VI) from solution. The bioreactor is based on an innovative process that combines bioreduction of Cr(VI) to Cr(III) by the bacterium Arthrobacter viscosus and Cr(III) sorption by a specific zeolite. Batch studies were conducted in a laboratory-scale bioreactor, taking into account different operating conditions. Several variables, such as biomass concentration, pH and zeolite pre-treatment, were evaluated to increase removal efficiency. The obtained results suggest that the Cr removal efficiency is improved when the initial biomass concentration is approximately 5 g L–1  and the pH in the system is maintained at an acidic level. Under the optimised conditions, approximately 100 % of the Cr(VI) was removed. The scale-up of the developed biofilm process operating under the optimised conditions was satisfactorily tested in a 150-L bioreactor.Xunta de Galicia - programa Angeles Alvariñ
Suspension polymerization processes

This is the pre-peer-reviewed version of an article submitted for publication in the journal, Chemical Engineeering and Technology[© Wiley-VCH Verlag], which has been published in its final form at: http://dx.doi.org/10.1002/ceat.201000210Industrial suspension polymerization usually proceeds by a free-radical mechanism\ud
to produce polymer beads. The size distribution of the polymer beads is often\ud
similar to that of the polymerizing drops in the reactor. That distribution is determined\ud
by the operating mechanisms of drop breakage and drop coalescence.\ud
Consequently, the value of the Reynolds number is significant and a potential\ud
change in flow regime must be considered in reactor scale-up. The choice of suspending\ud
agent, which can be a water-miscible polymer or a finely divided particulate\ud
solid, can affect both the drop size and the properties of the final product.\ud
High monomer conversions are attainable but reaction kinetics can be affected by\ud
increases in drop viscosity during the polymerization. Drop mixing, which sometimes\ud
takes place, can be slow, so that non-uniformity occurs in the final product.\ud
With copolymerization, complications can arise if the initiator, or one of the\ud
monomers, is partially soluble in the continuous phase. Adverse environmental\ud
impact of suspension polymerization can be avoided by cleaning and/or recycling\ud
the continuous phase when it leaves the reactor
Effect of Tween 80 on bubble size and mass transfer in a bubble contactor

Gas absorption in aqueous solutions with Tween 80 and absorption processes based on hydrodynamics and mass transfer is determined. The impact of surfactant concentration on gas holdup and gas-liquid interfacial area is analyzed, observing an increase of these parameters with surfactant concentration. The influence of liquid-phase contamination on the absorption process is investigated on the basis of the liquid-film mass transfer coefficient, removing the effect caused by the presence of a surfactant and the gas flow rate on the interfacial area and, thereby, on the volumetric mass transfer coefficient. The opposite effect on the mass transfer coefficient can be observed which decreases in the presence of the surfactant
Supercritical fractionation of rosemary extracts to improve the antioxidant activity

A supercritical CO 2 pilot plant was employed to extract rosemary (Rosmarinus officinalis L.) leaves and to thoroughly study the effect of time on the yield, composition and antioxidant activity of the different fractions produced. Six extraction assays were carried out, varying the fractionation procedure using a two-stage depressurization system coupled to the extractor vessel. The concentration of the main antioxidant compound in rosemary, i.e. carnosic acid, and the DPPH test were employed to evaluate the antioxidant power of the different fractions obtained. The goal was to develop a new fractionation scheme comprising two different periods of time, in which exhaustive extraction of the essential oil from the plant matrix was achieved while recovery of the antioxidant compounds was maximized.This work has been financed by project AGL2010-21565 (subprogram ALI) and project INNSAMED IPT-300000-2010-34 (subprogram INNPACTO) from the Ministerio de Ciencia e Innovación (Spain).Peer Reviewe
pH and Particle Structure Effects on Silica Removal by Coagulation

Coagulation is presented as an efficient alternative to reduce the silica content in effluents from recovered-paper mills that are intended to be recycled by a final reverse-osmosis (RO) step. Coagulation pretreatment by several polyaluminum chlorides (PACls) or FeCl3 was optimized prior to the RO process. PACls with low alumina content and high basicity achieved almost a 100 % removal of silica at pH 10.5. A good reduction of the silica content was attained without regulating the pH by adding one of these PACls. Silica removal was related to the structure of the produced clots in which cylindrical particles produced higher silica removal. All coagulants removed more than 50 % of the chemical oxygen demand (COD)
Online monitoring of vinyl chloride polymerization in a microreactor using raman spectroscopy

A novel capillary-based microfluidic device has been designed to follow the vinyl chloride polymerization reaction. The use of a co-flow generation system enabled obtaining monodisperse vinyl chloride droplets within 200 µm in diameter, each one being considered as a polymerization reactor. During polymerization VCM droplets were visualized with a high speed camera. At the end of the reaction PVC grains were observed with a Scanning Electron Microscopy technique. Real-time non-invasive Raman measurement has been performed on stationary vinyl chloride monomer droplets and has provided values of effective reaction orders n and effective rate constants k. This microdevice allowed the investigation in difficult conditions (pressure, temperature) with a minimal amount of reagents and consequently under safe conditions
Optimization of oxygen transfer through membrane diffusers for biological sweetening of biogas

Biological techniques for the removal of gaseous pollutants such as hydrogen sulfide\ud
(H2S) have proved to be effective, environmentally friendly, and economically\ud
viable. However, when high concentrations of H2S are treated, the process is\ud
severely restricted by the oxygen deficit in the liquid phase. The oxygen transfer\ud
efficiency provided by a membrane diffuser is evaluated under typical pressure\ud
and salinity conditions used for the biological treatment of H2S in biogas. The\ud
optimal operating parameters for enhanced oxygen transfer were determined.\ud
The addition of pure oxygen with a membrane diffuser to increase the oxygen\ud
transfer rate and the use of a nonaqueous phase to improve oxygen transfer in a\ud
bioscrubber system are also evaluated.Peer ReviewedPostprint (author’s final draft
Oxygen mass transfer rate in a pressurized lab-scale stirred bioreactor

Oxygen mass transfer from air to the liquid phase in bioreactors with aerobic cultures has long been a serious impairment to the productivity of various bioprocesses. An increase of the oxygen mass transfer rate (OTR) can be the key to overcome oxygen limitation. The influence of higher air pressure on OTR was measured and a significantly enhanced OTR could be obtained. The oxygen volumetric mass transfer coefficient (kLa) was described by a function of the air pressure in a stirred lab-scale pressurized bioreactor. The correlation obtained proved that kLa slightly decreased with higher air pressure, following a power function.The authors acknowledge the financial support provided by the Fundacao para a Ciencia e Tecnologia (Grant SFRH/BD/47371/2008)
Energy Evaluation of Ethanol Dehydration with Glycol Mixture as Entrainer

Extractive distillation of ethanol dehydration using glycols as entrainers is proposed. Specifically, ethanol dehydration of an azeotropic mixture in the presence of ethylene glycol + glycerol mixture is evaluated. Simulation is performed and the vapor‐liquid equilibrium of ethanol + water + ethylene glycol + glycerol is predicted with the NRTL model. Minimization of energy consumption in both extractive and regeneration columns is attempted. Optimal operating parameters of the process including glycol concentration in the solvent mixture, main feed, and entrainer feed trays, total number of theoretical trays, and heat supplied to the reboiler are determined in order to achieve a specified distillate purity of 99.9 mol % ethanol
Transparent and Inexpensive Microfluidic Device for Two-Phase Flow Systems with High-Pressure Performance

A design strategy allowing the development of an inexpensive microdevice with a cylindrical section able to work at high pressures is established. The setup combines good optical access, high‐pressure resistance, homogeneous operation conditions, fast process control and detection, and the ability to generate a stable two‐phase flow. The experiments are conducted in the ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate and supercritical carbon dioxide flow under isothermal conditions. The two‐phase flow system is observed with a high‐speed camera. An image processing procedure is performed on the films in order to determine the global two‐phase flow geometrical characterizations
A short multi-step flow synthesis of a potential spirocyclic fragrance component.

The search for novel chemical architectures displaying improved biological properties is a never-ending synthetic challenge. In this context many new test structures are often conceived by selecting and replicating specific design elements from naturally occurring molecules and displaying them in an alternative format by way of a new chemical assembly. Constructing these newly designed compounds can be a timely and expensive process especially when a large quantity of the target material is required for physiochemical and property testing. To permit easier scale-up and safer working practice, many chemical researchers are employing flow chemistry approaches to aid in their synthesis challenges. The preparation of a key spirocyclic lactone using flow-based reaction processing techniques is reported
Mechanistic modeling of pollutant removal, temperature, and evaporation in chemical air scrubbers

Chemical air scrubbers reduce the concentration of water-soluble components such as ammonia from the outgoing ventilation air through absorption in water, followed by chemical conversions and removal of the end products. A mechanistic model for a countercurrent air scrubber was set up. Mass balances for ammonia, hydrogen sulfide, nitrous oxide, and methane were implemented, as well as the water mass balance and heat balances. The model was validated against experimental data from a conventional fattening pig housing facility. The effect of influent characteristics, design parameters, and control handles on the removal efficiency, the temperature profile, and the water evaporation rate were investigated through simulation. The model was able to describe the behavior of a countercurrent chemical air scrubber