Highly selective palladium supported catalyst for hydrogenation of phenol in aqueous phase

Hydrogenation of phenol to cyclohexanone in aqueous phase, under mild conditions, has been carried out using palladium on different supports such as hydroxyapatite (HA), carbon (C), alumina (γ-Al₂O₃) and Al₂O₃-CWE synthesized with high surface area. High activity (100%) and selectivity (98%) to cyclohexanone was obtained using Pd/ Al₂O₃-CWE catalyst in 50 min under mild reaction conditions.     

Economical assessment of competitive enhanced limestones for CO2 capture cycles in power plants

CO₂ capture systems based on the carbonation/calcination loop have gained rapid interest due to promising carbonator CO₂ capture efficiency, low sorbent cost and no flue gases treatment is required before entering the system. These features together result in a competitively low cost CO₂ capture system. Among the key variables that influence the performance of these systems and their integration with power plants, the carbonation conversion of the sorbent and the heat requirement at calciner are the most relevant. Both variables are mainly influenced by CaO/CO₂ ratio and make-up flow of solids. New sorbents are under development to reduce the decay of their carbonation conversion with cycles. The aim of this study is to assess the competitiveness of new limestones with enhanced sorption behaviour applied to carbonation/calcination cycle integrated with a power plant, compared to raw limestone. The existence of an upper limit for the maximum average capture capacity of CaO has been considered. Above this limit, improving sorbent capture capacity does not lead to the corresponding increase in capture efficiency and, thus, reduction of CO₂ avoided cost is not observed. Simulations calculate the maximum price for enhanced sorbents to achieve a reduction in CO₂ removal cost under different process conditions (solid circulation and make-up flow). The present study may be used as an assessment tool of new sorbents to understand what prices would be competitive compare with raw limestone in the CO₂ looping capture systems.     

香奈儿背话的家族

“我们是一个很谨慎的家族．（对香奈儿）我们从来不说什么。香奈儿是关于可可·夏奈尔的，是关于卡尔的，是关于每一个在香奈儿工作、创作的人的．而不是关于维德摩尔家族的。”     

Control of the Basicity in Ni–MgO Systems: Influence in the Hydrogenation of Styrene Oxide

The addition of basic solutions to the reaction medium in the catalytic hydrogenation of styrene oxide improves the selectivity to 2-phenylethanol (used in perfumery) but also can favour condensation reactions. To study the influence of different basic sites on the reaction products, we prepared several catalysts by mixing a commercial magnesia (MgO), and other previously rehydrated (MgOr), with different amounts of NiO followed by reduction (NiMgO, 4NiMgO, NiMgOr, 4NiMgOr), and by mixing directly MgO with Ni (NiMgOa, 4NiMgOa). Ni–MgO catalysts showed the best conversion and selectivity to 2-phenylethanol values, arriving to 100% when increasing the MgO content. Interestingly, CO₂-TPD study of catalyst NiMgO indicates that metallic nickel covers the weakest basic sites of magnesia. On the other hand, CO₂-TPD profiles of Ni–MgOr and Ni–MgOa catalysts, which present low catalytic activity, showed an important amount of available basic sites that favour the formation of higher amounts of condensation products, which are responsible for the catalyst deactivation.     

Stereoselective Tandem Epoxidation–Alcoholysis/Hydrolysis of Glycals with Molybdenum Catalysts

Molybdenum catalysts are efficient and selective catalysts for the tandem epoxidation/alcoholysis or epoxidation/hydrolysis of glucal and galactal derivatives. In glucal derivatives the selectivity is mainly controlled by the allylic substituent at position 3 of the glycal, obtaining in general the products derived from the initial formation of the α‐epoxide (gluco) when this hydroxy group is protected, while products derived from the β‐epoxide (manno) are mainly obtained when it is unprotected. In galactal derivatives the estereoselectivity is always high to give the α‐epoxide (galacto) and independent of the protecting groups.     

Quantitative determination of octylphenol, nonylphenol, alkylphenol ethoxylates and alcohol ethoxylates by pressurized liquid extraction and liquid chromatography-mass spectrometry in soils treated with sewage sludges

Surfactants have one of the highest production rates of all organic chemicals. Non-ionic surfactants, especially alkylphenol ethoxylates, received most attention as precursors of estrogenic metabolic products generated during wastewater treatment. Alkylphenols (octyl and nonylphenol), alkylphenol polyethoxylates (APEOs), and alcohol ethoxylates (AEOs) have been determined in a Mediterranean forest soil (Mediterranean Rendzic Leptosol) amended with sludges from six waste water treatment plants (WWTPs) located in the Valencian Community. These compounds were isolated from soil by pressurized liquid extraction (PLE) using a mixture acetone-hexane (50:50 v/v), the extracts were cleaned up by solid-phase extraction (SPE) with C(18), and determined by liquid chromatography atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) using analytical standards for quantification. The method enabled high-reliable identification by monitoring the corresponding ammonium adduct [M+NH(3)](+) for AEOs and APEOs, and the deprotonated molecule [M-H](-) for octyl and nonylphenol. Recoveries, determined spiking soil samples at different concentrations, ranged from 89 to 94%, with limits of quantification from 1 to 100 microg kg(-1). Data obtained from a soil sample mixed with biosolids in the laboratory showed that these compounds are present at concentrations ranging from 0.02 to 5 mg kg(-1). According to these concentrations, levels of possible risk can be concluded for the presence of non-ionic surfactants in soil. However, further assessment will be necessary to establish the relationship between exposure and effect findings.     

Chromium–protein complexation studies by adsorptive cathodic stripping voltammetry and MALDI-TOF–MS

A methodology using stripping voltammetry has been elaborated to enable sensitive and reliable protein–chromium complexation measurements. Disturbing effects caused by adsorption of proteins on the mercury electrode were addressed. At low concentrations of proteins (<60–85 nM), chromium–protein complexation measurements were possible. Chromium(VI) complexation was quantitatively determined using differently sized, charged, and structured proteins: serum albumin (human and bovine), lysozyme, and mucin. Generated results showed a strong relation between complexation and protein size, concentration, and the number of amino acids per protein mass. Complexation increased nonlinearly with increasing protein concentrations. The nature of this complexation was based on weak interactions judged from combined results with MALDI-TOF–MS and adsorptive cathodic stripping voltammetry.     

Onion (<Emphasis Type="Italic">Allium cepa</Emphasis> L.) by-products as source of dietary fiber: physicochemical properties and effect on serum lipid levels in high-fat fed rats

The effect of industrial processes used to obtain onion by-products was evaluated. Fiber composition and physicochemical properties were assessed in order to choose the best process to obtain high-fiber ingredients. Moreover, the effect of the inclusion of the dietary fiber-rich onion by-products in a high-fat diet on serum lipids of rats was also evaluated. Bagasse was the best by-product since it showed the highest fiber content with a balanced soluble-to-insoluble fiber ratio and the best physicochemical properties. This fact is related to its high fiber content and also due to its composition, rich in uronic acids and polysaccharides, which explains its high cation exchange capacity, water-holding capacity and swelling capacity. In addition, the inclusion of Bagasse in a high-fat diet produced a reduction in the serum lipid and total cholesterol increases induced by high-fat diet. This effect could be related to the high cation exchange and swelling capacities that Bagasse showed, since these properties can create a concerted effect in reducing the number of intact micelles available, the transit time, and consequently the total time available for cholesterol and lipid absorption in the small intestine.     

A contribution to solve the problem of coating properties extraction in quartz crystal microbalance applications

The problem of coating properties extraction in quartz crystal resonator (QCR) applications is one of the challenging tasks of QCR applications, not completely solved even in theoretical conditions. The present work demonstrates that the problem is determined only for a set of three parameters of the coating, which concentrate the four coating properties. The following parameters are chosen: the surface mass density m8 = p1h1, the loss tangent tan delta1 = G'1/G'1, and the magnitude of the characteristic impedance /Z1(c)/ = (p1/G1/)(1/2). An algorithm is proposed that permits, in ideal conditions, an unambiguous extraction of these parameters, starting only from the admittance spectrum of a three-layer compound resonator, obtained from the one-dimensional transmission-line model (TLM) around the resonance. The algorithm introduces three additional improvements in relation to other routines: the calculation time is drastically reduced, the problem of erroneous solutions related to relative minima in typical fitting routines is eliminated, and a systematic error analysis in the extraction of the coating properties in real practice can be carried out. The use of the proposed algorithm as a tool for studying the effects of different phenomena such as slipping or surface roughness is introduced.