Production and purification of hydrogen by biogas combined reforming and steam-iron process

Cobalt ferrite and hematite with minor additives have been tested for production and purification of high purity hydrogen from a synthetic biogas by steam-iron process (SIP) in a fixed bed reactor. A catalyst based in nickel aluminate has been included in the bed of solids to enhance the rate of the reaction of methane dry reforming (MDR). The reductants resulting from MDR are responsible for reducing the oxides based on iron that will, in the following stage, be oxidized by steam to release hydrogen with less than 50 ppm of CO. Coke minimization along reduction stages forces to operate such reactors above 700 °C for reductions, and as low as 500 °C for oxidations to avoid coke gasification. To avoid problems such as reactor clogging by coke in reductions and/or contamination of hydrogen by gasification of coke along oxidations, steam in small proportions has been included in the feed with the aim of minimizing or even avoiding formation of carbonaceous depositions along the reduction stage of SIP. Since steam is an oxidant, it exerts an inhibiting effect upon reduction of the oxide, that slows down the efficiency of the process. It has been proved that co-feeding low proportions of steam with an equimolar mixture of CH4 and CO2 (simulating a poor heating value desulphurized biogas) is able to avoid coke deposition, allowing the operation of both, reductions and oxidations, in isothermal regime (700 °C). Empirical results have been contrasted with data found in literature for similar processes based in MDR and combined (or mixed) reforming process (CMR), concluding that the combination of MDR + SIP proposed in this work, taking apart economic aspects and complex engineering, shows similar yields towards hydrogen, but with the advantage of not requiring a subsequent purification process

Manufacturing to motorsport by students

[EN] The student s participation from the Polytechnic University of Valencia in the international competition Formula Student and the teacher s collaboration in the area of manufacturing processes has created a framework for the academic improvement. This article describes the conceptual and ideological framework of the project and also the new development.García Manrique, JA.; Peña Miñano, S.; Rivas Perea, ME. (2015). Manufacturing to motorsport by students. Procedia Engineering. 132:259-266. doi:10.1016/j.proeng.2015.12.493S25926613

On the classification and properties of noncommutative duplicates

We give an explicit description of the set of all factorization structures, or twisting maps, existing between the algebras k^2 and k^2, and classify the resulting algebras up to isomorphism. In the process we relate several different approaches formerly taken to deal with this problem, filling a gap that appeared in a recent paper by Cibils. We also provide a counterexample to a result concerning the Hochschild (co)homology appeared in a paper by J.A. Guccione and J.J. Guccione.Comment: 11 pages, no figure

Iron oxide ores as carriers for the production of high purity hydrogen from biogas by steam–iron process

Production of high purity hydrogen (<50 ppm CO) by steam–iron process (SIP) from a synthetic sweetened biogas has been investigated making use of a natural iron ore containing up to 81 wt% of hematite (Fe2O3) as oxygen carrier. The presence of a lab-made catalyst (NiAl2O4 with NiO excess above its stoichiometric composition) was required to carry out the significant transformation of mixtures of methane and carbon dioxide in hydrogen and carbon monoxide by methane dry reforming reaction. Three consecutive sub-stages have been identified along the reduction stage that comprise A) the combustion of CH4 by lattice oxygen of NiO and Fe2O3, B) catalyzed methane dry reforming and C) G–G equilibrium described by the Water-Gas-Shift reaction. Oxidation stages were carried out with steam completing the cycle. Oxidation temperature was always kept constant at 500 °C regardless of the temperature used in the previous reduction to minimize the gasification of eventual carbon deposits formed along the previous reduction stage. The presence of other oxides different from hematite in minor proportions (SiO2, Al2O3, CaO and MgO to name the most significant) confers it an increased thermal resistance against sintering respecting pure hematite at the expense of slowing down the reduction and oxidation rates. A “tailor made” hematite with additives (Al2O3 and CeO2) in minor proportions (2 wt%) has been used to stablish comparisons in performance between natural and synthetic iron oxides. It has been investigated the effect of the reduction temperature, the proportion of methane to carbon dioxide in the feed (CH4:CO2 ratio) and the number of repetitive redox cycles

Biogas to high purity hydrogen by methane dry reforming in TZFBR+MB and exhaustion by Steam-Iron Process. Techno–economic assessment

A techno-economic study has been carried out with the aim of analyzing the performance (product distribution and energy yields) and estimating the production costs of high purity hydrogen obtained from biogas. For such purpose and taking advantage of empirical data developed in our laboratory, it has been proposed a system consisting of a two-zone fluidized bed reactor aided by a system of permselective (Pd/Ag) metallic membranes inserted in the fluidized bed (TZFBR+MB), and a battery of several fixed bed reactors operating cycles of reduction and oxidation (Steam-Iron Process -SIP-). The feed has always been an equimolar mixture of CH4 and CO2 simulating a sweetened biogas. The first reactor (TZFBR+MB) can produce a stream of pure hydrogen (i.e. PEMFC quality) as permeated flow through the MB, and a retentate stream rich in all species resulting from the methane dry reforming reaction (MDR) and the water gas shift equilibrium (WGS). The singularity of this kind of complex reactors is that regeneration of the catalyst is performed in the same reactor and simultaneously to the MDR reaction because of the two-zone. Due to the reductive behavior of the retentate stream, it can be fed to a bed of solid where up to two different oxygen carriers (iron oxide with additives and cobalt ferrite) can be reduced to their metallic state. Once the solid has been completely reduced, it can be reoxidized with steam releasing a high purity hydrogen stream. Both reactors (i.e. TZFBR+MB and SIP) have been coupled in different degrees. A performance (hydrogen and energy yields) as well as costs analysis (fixed assets and operating costs) have been performed with the aid of Aspen HYSYS v9.0, used for dimensioning the equipment needed to process up to 1350 kg/h of biogas. On this way, the integrated process enhances the efficiencies of every single process allowing pure hydrogen yields up to 68% at 575 °C in the TZFBR+MB and an overall energy efficiency greater than 45%. Production costs have been found to be in the range from 4 to 15 €/kg, still high but not so far away from the target of DOE fixed in 2 $/kg by 2020

Rasgos sedimentarios de los conglomerados miocénicos del borde noreste de la Depresión de Granada

Este trabajo da una primera interpretación sedimentaria y una reconstrucción paleogeográfica de los materiales conglomeráticos neógenos de parte de la Depresión de Granada. El modelo sedimentario propuesto consiste en abanicos aluviales que penetran en medio marino. En una fase posterior, se establece un régimen fluvial que desemboca en zonas lacustres, eventualmente evaporÍticas. [ABSTRACT] This paper offers a first sedimentary interpretation aod a paleogeographic reconstruction for the neogenic conglomerates in a part of Granada Basin. The proposed sedimentary ruodel consists on alluvial fans going into marine environment. Later, a braided fluviatile pattern connected downstream with lacllstrine areas with episodic evaporite deposits establishes in this place

Improving CO2 methanation performance by distributed feeding in a Ni-Mn catalyst fixed bed reactor

It has been successfully demonstrated the effect of feeding reactants in distributed manner for the reaction of methanation of CO2. This operation mode has improved not only the selectivity towards CH4, but also the overall process performance. A fixed bed reactor, loaded with Ni-Mn based catalyst, was operated co-feeding both CO2 and H2, but alternatively feeding one of them through several lateral inlets. Preserving the same global W/FCO2 ratio, the side distribution of CO2 allowed to clearly increase the activity of the process (e.g., at 375 °C, the conversion with distributed feeding was around 35% higher than that for the conventional one: XCO2 = 0.12 vs. XCO2 = 0.09). Furthermore, a substantially lower selectivity towards non-desired CO was obtained at any conversion level (e.g., SCO = 0.45 vs. SCO = 0.70, when XCO2 = 0.10). In addition, a more homogeneous temperature profile could be achieved in the bed without increasing the severity of hot spots appearance. On the contrary, side distribution of H2 always led to similar or worse results than for the conventional co-feeding configuration