Methane Reforming with H2S and Sulfur for Hydrogen Production: Thermodynamic Assessment

Nowadays, most ofthe hydrogen is obtained from fossil fuels. Atthe same time, the effort and resources dedicated to the developmentof sustainable hydrogen manufacturing processes are rapidly increasingto promote the energy transition toward renewable sources. In thisdirection, a potential source of hydrogen could be hydrogen sulfide,produced as a byproduct in several processes, and in particular inthe oil extraction and refinery operations. Methane reforming usingH(2)S has recently attracted much interest for its economicand environmental implications. Its conversion, in fact, providesa viable way for the elimination of a hazardous molecule, producinga high-added value product like hydrogen. At the same time, some ofthe still open key aspects of this process are the coke depositiondue to thermal pyrolysis of methane and the process endothermicity.In this work, the methane reforming with H2S by co-feedingsulfur is investigated through a detailed thermodynamic analysis asa way to alleviate the critical aspects highlighted for the process.A parametric analysis was conducted to assess the best thermodynamicconditions in terms of pressure, temperature, and feed composition.Changing the sulfur, H2S, and methane feed compositioncan enhance the system by improving the hydrogen production yield,reducing the carbon and sulfur deposition, increasing the H2S removal efficiency, and reducing the necessary thermal duty

Vapor pressure curves and isobaric vapor-liquid equilibrium for binary systems with compounds obtained from glycerol to be used as components of a bio-diesel mixture

The search of new renewable fuels and the interest of finding new uses for the abundant subproducts of many industrial processes have prompt Eni S.p.A to develop a technology for producing biofuels from glycerol. One of the compounds involved in this process is 2-ethyl-4-ethoxymethyl-1,3-dioxolane (PrEDO). In this paper their temperature - vapor pressure curve has been determined experimentally as well as binary vapor-liquid equilibrium data at different pressures of systems where this compound is involved. The experimental vapor pressure data of PrEDO have been fitted with the Antoine equation. The vapor liquid equilibrium data have been correlated and calculated with UNIFAC, UNIQUAC, NRTL and Wilson to analyze their use when designing distillation processes.Eni S.p.A. is gratefully acknowledged for the financial support

Hydrocracking of long chain linear paraffins

The hydrocracking reactivity of two model compounds, namely n-C(16)H(34) (n-C16) and n-C(28)H(58) (n-C28), was investigated on a Pt/SiO(2)-Al(2)O(3) catalyst. Conversion and products distribution have been determined under a wide range of operating conditions (i.e. pressure: 20-80 bar; temperature: 270-330 degrees C; weight hourly space velocity: 0.33-1.0 h(-1): H(2)/n-paraffin feeding ratio 0.05-0.15 wt/wt). The latter were changed according to a central composite design. The present paper summarises the results obtained on both the model paraffins, depending on the reaction conditions. A first, simple kinetic elaboration is also presented, based on an ideal PFR model and a first order kinetics. The reaction confirmed to be first order with respect to the n-paraffin. Experimental data showed that for both n-C16 and n-C28 conversion was affected by H(2)/n-paraffin ratio. The change of conversion was explained in terms of vapour liquid equilibrium (VLE), which in turn is affected by the H(2)/n-paraffin ratio, so leading to a different vaporisation degree of reactant. In agreement with the VLE data, the effect of H(2)/n-paraffin on conversion was lower for n-C28. VLE calculations have been carried out to estimate the H(2) partial pressure and degree of vaporisation of the normal paraffin. The reaction order for hydrogen was -1 and -0.5 for n-C16 an n-C28, respectively. However, in the case of n-C16 the data obtained at the lower bound of the pressure range examined displayed an increase of the reaction order. The apparent activation energy was calculated after correction of the contact time taking into account the liquid-vapour equilibrium: similar values have been estimated for n-C16 and n-C28, ca. 32 and 31 kcal/mol, respectively

Influence of pH on the kinetics of hydrolysis reactions: the case of epichlorohydrin and glycidol

Glycidol (GL) and epichlorohydrin (EPI) are two widely used molecules in chemical, pharmaceutical and food industry applications. However, their use in aqueous environments causes the formation of compounds, like monochloropropanediol (MCPD) and dichloropropanol (DCP), reported as dangerous for human health and therefore regulated by severe law restrictions. To identify the conditions leading to such species and design the corresponding processes in order to prevent their formation, hydrolysis and chlorination of EPI and GL, together with dehydrohalogenation of DCP and MCPD, have been systematically analysed. Different reaction conditions in terms of temperature, pH and chloride ion concentration have been experimentally investigated and the concentration of the involved species was tracked over time by gas chromatography and high-performance liquid chromatography. These experimental data were fitted through a kinetic model, which allowed a general expression of the observed rate constant of each reaction as a function of temperature and pH to be quantified. In particular, the reaction rates are conveniently expressed as combinations of three contributions: alkaline, neutral and acid. The corresponding rate laws explicitly account for the critical role of pH. The developed mechanistic model exhibits good prediction ability and may represent the basis for optimising processes employing EPI and GL

Alkylation of methyl linoleate with propene in ionic liquids in the presence of metal salts

Vegetable oils and fatty acid esters are suitable precursor molecules for the production of a variety of bio-based products and materials, such as paints and coatings, plastics, soaps, lubricants, cosmetics, pharmaceuticals, printing inks, surfactants, and biofuels. Here, we report the possibility of using Lewis acidic ionic liquids (ILs) to obtain polyunsaturated ester dimerization-oligomerization and/or, in the presence of another terminal alkene (propene), co-polymerization. In particular, we have tested the Lewis acidic mixtures arising from the addition of a proper amount of GaCl3 (X > 0.5) to two chloride-based (1-butyl-3-methylimidazolium chloride, [bmim]Cl, and 1-butylisoquinolium chloride, [BuIsoq]Cl) or by dissolution of a smaller amount of Al(Tf2N)3 (X = 0.1) in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][Tf2N]. On the basis of product distribution studies, [bmim][Tf2N]/Al(Tf2N)3 appears the most suitable medium in which methyl linoleate alkylation with propene can compete with methyl linoleate or propene oligomerization

n-Hexadecane hydrocracking Single-Event MicroKinetics on Pt/H-beta

[EN] The Single-Event MicroKinetic (SEMK) model constructed for gas-phase hydroconversion of light n-alkanes on large-pore USY zeolites was applied, for the first time, to the hydrocracking of n-hexadecane on a Pt/H-Beta catalyst. Despite the 12-ringed pore channels, shape selectivity was observed in the formation of ethyl side chains. Additionally, heavy feed molecules such as n-hexadecane lead to physisorption saturation of the catalyst pores by strong Van der Waals interactions of the long alkyl chains with the zeolite framework. Intermolecular interactions and packing efficiencies in the pores induce deviations from typical Henry-regime physisorption characteristics as the physisorption selectivity, which is expected to increase with increasing carbon number, appeared to be independent of the latter. Micropore saturation effects were described by the 'size entropy' which quantifies the difference in standard entropy loss between physisorption in the Henry regime and hindered physisorption on a saturated surface. The size entropy is proportional to the catalyst loading with physisorbed species and the adsorbate carbon number. The addition of a size entropy term in the SEMK model, amounting to 102J mol(-1) K-1 for a hexadecane molecule at full saturation, allowed accurately reproducing the contribution of secondary isomerization and cracking reactions, as quantified by means of a contribution analysis. (C) 2012 Elsevier B.V. All rights reserved.This work was funded by the European Research Institute of Catalysis and the European Community’s Sixth Framework Programme. This work was also supported by the Research Board of Ghent University (BOF), the Interuniversity Attraction Poles Programme–Belgian State–Belgian Science Policy and the Long Term Structural Methusalem Funding by the Flemish Government. Financial support by the Comisión Interministerial de Ciencia y Tecnología (CICYT) of Spain through the Project CTQ2010-17988/PPQ is also gratefully acknowledged.Vandegehuchte, BD.; Thybaut, JW.; Martinez Feliu, A.; Arribas Viana, MDLD.; Marin, GB. (2012). n-Hexadecane hydrocracking Single-Event MicroKinetics on Pt/H-beta. Applied Catalysis A General. 441:10-20. doi:10.1016/j.apcata.2012.06.054S102044

Regulatory T cell frequency in patients with melanoma with different disease stage and course, and modulating effects of high-dose interferon-α 2b treatment

<p>Abstract</p> <p>Background</p> <p>High-dose interferon-alpha 2b (IFN-α 2b) is the only approved systemic therapy in the United States for the adjuvant treatment of melanoma. The study objective was to explore the immunomodulatory mechanism of action for IFN-α 2b by measuring serum regulatory T cell (Treg), serum transforming growth factor-β (TGF-β), interleukin (IL)-10, and autoantibody levels in patients with melanoma treated with the induction phase of the high-dose IFN-α 2b regimen.</p> <p>Methods</p> <p>Patients with melanoma received IFN-α 2b administered intravenously (20 MU/m²each day from day 1 to day 5 for 4 consecutive weeks). Serum Treg levels were measured as whole lymphocytes in CD4⁺cells using flow cytometry while TGF-β, IL-10, and autoantibody levels were measured using enzyme-linked immunosorbent assays.</p> <p>Results</p> <p>Twenty-two patients with melanoma received IFN-α 2b treatment and were evaluated for Treg levels. Before treatment, Treg levels were significantly higher in patients with melanoma when compared with data from 20 healthy subjects (<it>P </it>= 0.001; Mann-Whitney test). Although a trend for reduction of Treg levels following IFN-α 2b treatment was observed (average decrease 0.29% per week), statistical significance was not achieved. Subgroup analyses indicated higher baseline Treg levels for stage III versus IV disease (<it>P </it>= 0.082), early recurrence versus no recurrence (<it>P </it>= 0.017), deceased versus surviving patients (<it>P = </it>0.021), and preoperative neoadjuvant versus postoperative adjuvant treatment groups (not significant). No significant effects were observed on the levels of TGF-β, IL-10, and autoantibodies in patients with melanoma treated with IFN-α 2b.</p> <p>Conclusions</p> <p>Patients with melanoma in this study showed increased basal levels of Treg that may be relevant to their disease and its progression. Treg levels shifted in patients with melanoma treated with IFN-α 2b, although no firm conclusions regarding the role of Tregs as a marker of treatment response or outcome can be made at present.</p

ASSESSING IDENTIFICATION RESTRICTIONS IN STRUCTURAL VECTOR AUTOREGRESSIVE MODELS: A GENERALISED, DATA-DRIVEN APPROACH

Shock identification in Vector Autoregressive (VAR) models has often put researchers in a position from which they can only rely, for the purpose of obtaining a structural representation of the economic mechanisms that they try to capture, on a number of assumptions derived mostly from economic theory. Many of these assumptions cannot be easily tested jointly with the specification of the model. Recent developments in the VAR literature, drawing on the generical assumption of independent (and, in many cases, non-Gaussian) structural shocks, have demonstrated that it is possible to identify structural shocks by using only the distribution of reduced-form shocks and taking advantage of the information provided by its moments even beyond the variance-covariance matrix, offering a new way to evaluate – or even test – previous identification strategies. The primary question driving the research at the basis of the following work is about looking for suitable ways in which we can assess the plausibility of a priori shock identification assumptions (depending on the category they belong to) in the light of the results obtained with these new models