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International audience; The main objective of this work concerns the coupling of biomass gasification reaction and CO2 sorption. The study shows the feasibility to promote biomass steam gasification in a dense fluidized bed reactor with CO2 sorption to enhance tar removal and hydrogen production. It also proves the efficiency of CaO-Ca12Al14O33/olivine bi-functional materials to reduce heavy tar production. Experiments have been carried out in a fluidized bed gasifier using steam as the fluidizing medium to improve hydrogen production. Bed materials consisting of CaO-based oxide for CO2 sorption (CaO-Ca12Al14O33) deposited on olivine for tar reduction were synthesized, their structural and textural properties were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and temperature-programmed reduction (TPR) methods, and the determination of their sorption capacity and stability analyzed by thermogravimetric analysis (TGA). It appears that this CaO-Ca12Al14O33/olivine sorbent/catalyst presents a good CO2 sorption stability (for seven cycles of carbonation/decarbonation). Compared to olivine and Fe/olivine in a fixed bed reactor for steam reforming of toluene chosen as tar model compound, it shows a better hydrogen production rate and a lower CO2 selectivity due to its sorption on the CaO phase. In the biomass steam gasification, the use of CaO-Ca12Al14O33/olivine as bed material at 700 A degrees C leads to a higher H-2 production than olivine at 800 A degrees C thanks to CO2 sorption. Similar tar concentration and lighter tar production (analyzed by HPLC/UV) are observed. At 700 A degrees C, sorbent addition allows to halve tar content and to eliminate the heaviest tars.

Al 2 O 3 based grain-sintered filter element support was first impregnated with a fine, wet-milled suspension of a MgO–Al 2 O 3 and successively with nickel nitrate hexahydrate. The catalytic filter candle was inserted in the freeboard of a 0.1 m I.D. fluidized bed biomass gasifier, in order to obtain a very compact gasification and hot gas cleaning unit. Continuous catalytic steam gasification runs of almond shells have been performed in a temperature range of 808–813 °C (maintained by means of an electric furnace), and the volume composition of the product gas has been analyzed by means of IR, UV and TCD facilities for online detection of CO, CO 2 , CH 4 , H 2 , NH 3 and H 2 S. A 20 h test has been performed with intermediate char burning steps. The measured gas yield was 2.09 Nm 3 /kg daf , meanwhile the gas composition in % by volume was H 2 = 56, CO = 22, CO 2 = 20, and CH 4 = 2. NH 3 and H 2 S in the dry gas were 60–80 ppmv and 10–15 ppmv, respectively.

Changes in fluorescence emission due to non-covalent analyte-fluorophore interactions in silica gel plates are studied and used as a general detection procedure for thin-layer chromatography (TLC). The presence of the analyte modifies the microenvironment of the fluorophore and thus changes the balance between radiative (k(r)) and non-radiative (k(nr)) emission constants. A model is proposed for analyte-fluorophore induced electrostatic interactions, which depend on analyte polarizability and are responsible for fluorescence enhancements. As consequence of these induced interactions, the analyte creates an apolar environment that prevents non-fluorescent decay mechanisms, decreasing k(nr). On the other hand, the effect of an increase in refractive index on k(r) is investigated, as it contributes to some extent to fluorescence enhancements in silica gel medium. Changes in fluorescence emission should be regarded as a general property of fluorophores in the presence of analytes, and criteria that fluorophores should meet to be used as sensitive TLC probes are discussed here.

The Miscanthus X giganteus (MXG) presents many advantages (high yield, perennial crop, easy harvesting…) so it can be considered as a good candidate in terms of renewable energy sources. Several works have been carried out and were devoted to the MXG, especially in the agricultural field, but this study is the first which deals with gasification in order to produce syngas. The catalytic steam gasification of MXG in a fluidised bed reactor into presence of olivine based catalysts was investigated. Three parameters were studied, the temperature (800 °C and 900 °C), the pellets size (6 mm and 8 mm) and the nature of catalyst (olivine and Ni/olivine). Noteworthy is the efficiency shown by the Ni/olivine at 800 °C, which leads to the production of 1.7 m 3 kg − 1 daf of gas, containing 50% of H 2 . Ni/olivine catalyst was characterised by XRD, TPR and SEM-EDX in order to monitor its structural changes during the process. Moreover, a solvent system of tar recovery was tested, which allows to obtain a more representative set of the whole tars. Then, the tars composition was determined by GC/MS. The identification of different compounds shows the presence of different PAHs, in majority naphthalene.

The new compound 3-((2,5-dimethoxyphenyl)ethynyl)thiophene has been synthesised by Sonogashira coupling. A modified electrode coated with a polythiophene film bearing a quinone moiety was obtained by electropolymerisation of the thienyl group followed by anodic oxidation of para-dimethoxyphenyl group. The cyclovoltammetric response resulting from the reaction of glutathione with the benzoquinone moiety was investigated. The responses of the modified electrode as a new potentiometric sensor of reduced thiols are proposed.

Improved methods for separation and quantitative determination of hydrocarbon types from gas oil have been developed, which were based on high-performance thin-layer chromatography with ultraviolet and fluorescence scanning densitometry using horizontal elution. One of the methods allows the separation, detection, and determination of alkanes and naphthenes to be carried out, using berberine-impregnated silica gel HPTLC plates, elution with n-hexane, and berberine-induced fluorescence detection at 365 nm. Another developed method allows total aromatics to be determined using silica gel HPTLC plates by elution with n-hexane and acetone, and UV detection. In turn, PACs over three aromatic rings can be determined on either silica gel or caffeine-impregnated silica gel HPTLC plates, elution with n-hexane, and selective detection using native fluorescence at 365 nm. Concentrations lower than 5 wt% can be determined using this technique. In addition, a technique for an efficient, baseline-resolved separation of a gas oil according to the number of aromatics rings (mono + di-, tri-, and polyaromatic compounds with more than three rings) is presented here. This technique involves a multistep elution on a mixed (silica gel and caffeine-impregnated silica gel HPTLC plate) using a counter-elution device, and UV detection.

Different methodologies, based on planar chromatography/detection with densitometry, have been used to analyse compound classes (also known as hydrocarbon group type (HGT)) in samples coming from petroleum and coal conversion. The main problem encountered to analyse these samples is the choice of standard: because of the high variability of the signal that is dependent of molecular structure, one pure hydrocarbon does not reflect the response of a mixture. However, a step based on thin layer chromatography at preparative scale has allowed the fractionation of sample to obtain its derived standards. After this, alkanes have been quantified by fluorescence in presence of berberine sulfate and aromatic compounds have been detected by UV after separation by high performance thin layer chromatography (HPTLC) at analytical scale. The feasibility of the planar chromatography has been tested. The quantitative results obtained for different samples are in agreement with those provided using well-established techniques in the petrochemical industry and the coal-derived product (CDP) analysis.

Two alternative methods, based on Thin-Layer Chromatography (TLC) with Fluorescence Scanning Densitometry have been developed for characterization of heavy liquids from copyrolysis of different kinds of biomass and plastics in autoclaves under inert atmosphere.

In order to improve the understanding of the mechanisms involved in the adsorption of volatile organic compounds (VOCs) on coal materials, and in order to predict selectivity values between given pairs of VOCs, an LSER (Linear Solvation Energy Relationship) approach has been used. Gas–solid partition coefficients at infinite dilution of 14 VOCs on a commercial coal material have been obtained by the gas chromatographic method of elution by characteristic point. Analysis of the gas–solid partition coefficients by the LSER equation developed by Abraham et al. [1] shows that the main interactions involved in the adsorption process are general dispersion interactions, and hydrogen-bond interactions. The coefficients in the LSER equation can be used to characterize the adsorbent, and are found to be in good agreement with its chemical composition. The LSER equation has also been used to predict the selectivity of the adsorbent towards various pairs of VOCs.

International audience; The present work investigates the potential of two analytical tools to ensure rapid and affordable analysis of tar, produced during biomass gasification. On one hand, high performance thin layer chromatography (HPTLC) provides quantitative and qualitative information on tar composition and on the other, UV spectroscopy allows rapid quantitative total polycyclic aromatic hydrocarbon (PAHs) determination. An original separation method, based on HPTLC coupled with UV and fluorescence detection, enables the resolution of non-volatile hydrocarbons into families from two to five aromatic rings, with a difference between condensed and non-condensed structures. The method uses a two-stage migration with ethyl acetate/n-hexane and n-hexane on RP-plates, at -23 degrees C. HPTLC is also used for tar quantification, by means of standard addition method after merging all the aromatic compounds in one peak. Thereafter, two approaches are proposed for UV quantification: the first, UV direct quantification, consists in determining the absorbance and concentration of a reference sample, which permits to calculate unknown tar concentration. The second, based on UV spectra deconvolution (UVSD), calculates tar concentration by UV deconvolution of selected standard spectra without the need of reference samples. Both approaches were applied on thirty-seven samples formed in three gasifiers, a Bubbling Fluidized Bed (BFB), an Internal Circulating Bubbling Fluidized Bed (ICBFB) and a Circulating Fluidized Bed (CFB). All the methods applied show a good agreement between the results obtained and the concentration of tar determined by HPLC/UV, the reference method.

1 table., Berberine is a yellow alkaloid naturally produced by a diversity of plants. It is extracted from the roots, rhizome, and stem bark of several plants. This natural product has been used for centuries in the Chinese medicinal herb. Berberine presents a wide range of pharmacological applications such as antidiabetic, hypolipidemic, antihypertensive, anti-inflammatory, antioxidant, antidepressant, anticancer, antidiarrheal, hepatoprotective, and, above all, antimicrobial. It has been tested clinically in the treatment of oriental sore, diarrhea, trachoma, diabetes mellitus type 2, hypercholesterolemia, and congestive cardiac failure. This alkaloid is also used in the treatment of gastric and inflammatory diseases and more recently is being investigated for its application in neurology, cardiology, and oncology.

This paper concerns the cleaning of the hot gas produced by steam gasification of biomass in a fluidized bed. The cleaning takes place in a catalytic filter candle device placed directly in the freeboard of the bed. Such integration results in a compact processing unit and increased thermal efficiency; the result of the cleaning being carried out directly at the reactor outlet temperature. It thus lends itself to exploitation in distributed power generation systems utilizing renewable energy sources. Results are reported for runs performed in a bench scale fluidized bed steam gasifier fitted with a single full-size catalytic candle filter. Tar and particulates in the product gas were sampled in accord with technical specification CEN/TS 15439 with analysis by UV and fluorescence spectroscopy.

6 Figures, 2 Tables, A large number of analytes, including non-fluorescent ones, can be sensitively detected by fluorescence scanning densitometry using silica gel HPTLC plates impregnated with a solution of coralyne cation. This is carried out by the variation, increase or decrease, that the corresponding analyte induces on native coralyne emission at a given excitation wavelength. A similar phenomenon was previously described for berberine cation, and Reichardt's dye probes. However, the sensitivity of coralyne in HPTLC detection of non-fluorescent, structurally different analytes (e.g., long-chain alkanes, alcohols, alkylbromides, neutral lipids) is superior to that of the above-mentioned probes. In this work, the analytical viability of this phenomenon for HPTLC detection using coralyne as a probe is explored, and fluorescent responses of a number of analytes on the coralyne system are rationalized in the light of a previously proposed model. This establishes that the resulting intensity for a probe in the presence of a given compound can be explained as a balance between radiative (contribution of non-specific interactions) and non-radiative processes (specific interactions), the latter producing fluorescence quenching. Experimental results and proposed model suggest that this phenomenon may be general for practically all kinds of analytes., The authors thank the Spanish Ministerio de Educación y Ciencia (MEC) and the Diputación General de Aragón (DGA) for financial support (projects CTQ2005-00227/PPQ and PM010, respectively).

6 Figuras., Many chemical compounds, including nonfluorescent ones, induce changes in the fluorescence spectra of certain probes, such as berberine cation and Reichardt's betaine, both in the absence and the presence of solvent, that affect almost exclusively emission intensity. In this work, the application of fluorescence detection by intensity changes (FDIC) to HPLC and TLC chromatographic systems with fluorescence detectors has been studied. FDIC detection is of special interest in detecting nonfluorescent analytes, either in HPLC or in TLC mode. It does not involve covalent interactions, and the dielectric permittivity (ε) of the medium plays an important role. The balance between nonspecific and specific interactions produces either an increase or a decrease in fluorescence intensity. Therefore, the influence of chromatographic conditions and chemical structure of analytes on the sign and magnitude of fluorescence peaks for sample detection in HPLC and TLC systems has been discussed. In general, probe nature and concentration determine response and detection sensitivity for a given sample in TLC and HPLC. As solubility and fluorescence properties in solvents determine the operating conditions for a FDIC probe in HPLC mode, nature and flows of mobile phase and solvent are important for chromatographic response and detection sensitivity., Authors thank the Spanish Ministerio de Ciencia y Tecnología (MCyT) and Ministerio de Educación y Ciencia for financial support (projects PPQ2001-2388 and CTQ2005-00227/PPQ). E.M.G. acknowledges MCyT for a grant.

Petroleum is fractionated according to its boiling point by distillation methods. Depending on the boiling point range of the sample, fractionated products fall into three main categories: light, middle and heavy distillates. Middle distillates (from approximately 150°C to 400°C, which approximately corresponds to C9-C24) are mostly used for heating and transportation fuels (e.g., diesel, jet fuel, gas oil, aviation turbine oils, kerosene).

A straight run gas oil has been hydrotreated with a commercial CoMo/Al2O3 catalyst, under variable conditions of severity, in order to yield processed products containing a variable amount of residual sulfur. These products have been characterized by simulated distillation, gas chromatography with sulfur-selective detection (GC−SCD), and thin-layer chromatography. The sulfur compounds have been grouped into distinct representative families. The rate constants for the reaction of desulfurization of the considered groups and the apparent rate order with respect to some individual sulfur compounds have been determined. The following hydrocarbon groups have been determined in the hydrotreated products by analytical thin-layer chromatography−densitometry: alkanes, cycloalkanes, total aromatics, and polyaromatic compounds (PACs). The straight run gas oil has been submitted to fractionation by preparative thin-layer chromatography, and the resulting fractions of alkanes, cycloalkanes, and aromatics have been ch...

A bench-scale fluidized-bed biomass gasification plant, operating at atmospheric pressure and temperature within the range 800–820 °C, has been used to test an innovative gas cleaning device: a catalytic filter candle fitted into the bed freeboard. This housing of the gas conditioning system within the gasifier itself results in a very compact unit and greatly reduced thermal losses. Long term (22 h) tests were performed on the gasifier both with and without the catalytic candle filter, under otherwise identical conditions. Analysis of the product gas for the two cases showed the catalytic filtration to give rise to notable improvements in both gas quality and gas yield: an increase in hydrogen yield of 130% and an overall increase in gas yield of 69% – with corresponding decreases in methane and tar content of 20% and 79%, respectively. HPLC/UV analysis was used to characterize the tar compounds.

Hydrocarbon group-type analysis (HGTA) is a common technique for characterization of complex mixtures derived from raw materials such as coal, petroleum, or biomass. In these and other, related, samples, trying to achieve extensive separation of all the components would be very difficult at least, and most of the relevant properties of the samples can be related to the amounts of the different types of hydrocarbon. Groups of interest depend mainly on the nature of the sample, and some kind of liquid chromatography is usually involved in the most common HGTA methods. Thin-layer chromatography (TLC) can nowadays usually be used instead of HPLC, resulting in several advantages in terms of speed, cost, and general convenience. Detection and quantification of the different peaks might involve the use of special equipment, e.g. in TLC-flame ionization detection (FID) methods, although it can also be accomplished by means of UV and fluorescence scanning densitometry. In this paper, we describe a series of TLC-ba...