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M Menendez - One of the best experts on this subject based on the ideXlab platform.
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pure hydrogen from biogas intensified methane dry reforming in a two zone fluidized bed reactor using permselective membranes
Chemical Engineering Journal, 2019Co-Authors: P. Duran, A Sanzmartinez, J Soler, M Menendez, Javier HerguidoAbstract:Abstract Methane dry reforming of biogas can be a sustainable source of hydrogen but the development of this technology is hindered by limitations such as endothermicity and Catalyst deactivation by coke. A two zone fluidized bed reactor coupling permselective Pd/Ag membranes counteracts them and allows to intensify the process obtaining a stable pure hydrogen production. Here we report the effect of operation variables (i.e., temperature, total bed height, nature and partial pressure of regenerative agent, relative height of the Regeneration and reaction zones, and use of an activation period) on the yield to hydrogen and stability of the process. Hydrogen over-yields, compared with the conventional fluidized bed reactor, in the range of +200% to +100% were obtained for the entire interval of temperatures 475–575 °C whilst maintaining stable operation by continuous Catalyst Regeneration. Around 70% of it was pure hydrogen coming from the permeate side of the membranes. The proposed reactor configuration greatly increases both methane conversion and selectivity to hydrogen (expressed as H2/CO ratio), not only in relation to our own conventional reactor findings but also regarding other published results.
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stable hydrogen production by methane steam reforming in a two zone fluidized bed reactor experimental assessment
Journal of Power Sources, 2013Co-Authors: L Perezmoreno, Javier Herguido, J Soler, M MenendezAbstract:Abstract The Two Zone Fluidized Bed Reactor concept is proposed for hydrogen production via the steam reforming of methane (SRM) including integrated Catalyst Regeneration. In order to study the effect of the contact mode, the oxidative SRM has been carried out over a Ni/Al 2 O 3 Catalyst using a fixed bed reactor (fBR), a conventional fluidized-bed reactor (FBR) and the proposed two-zone fluidized bed reactor (TZFBR). The technical feasibility of these reactors has been studied experimentally, investigating their performance (CH 4 conversion, CO and H 2 selectivity, and H 2 global yield) and stability under different operating conditions. Coke generation in the process has been verified by several techniques. A stable performance was obtained in the TZFBR, where coke formation was counteracted with continuous Catalyst Regeneration. The viability of the TZFBR for carrying out this process with a valuable global yield to hydrogen is demonstrated.
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particle mixing in a two section two zone fluidized bed reactor experimental technique and counter current back mixing model validation
Industrial & Engineering Chemistry Research, 2013Co-Authors: Ignacio Julián, Javier Herguido, M MenendezAbstract:Effective particle circulation between the two zones is a prerequisite for ensuring the simultaneous reaction and Catalyst Regeneration inside a two-zone fluidized bed reactor (TZFBR). An appropriate degree of particle mixing provides a steady state catalytic operation, whereas poor solid circulation between the bed zones leads to unhampered Catalyst deactivation. To achieve effective control of the fluid dynamic regime within the two bed regions, a new design has been proposed with a different cross sectional area in each zone. The transition angle (α) between these zones represents the most characteristic feature of the so-called two-section TZFBR (TS-TZFBR). In the present study, the influence of operational variables (α, gas velocities, gas distributor location) on the particle circulation has been determined. Phosphorescent particles have been used as optical tracers to measure the solid axial mixing between the zones in a cold pseudo-2D TS-TZFBR facility. Additionally, a modified counter-current bac...
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particle mixing in a two section two zone fluidized bed reactor experimental technique and counter current back mixing model validation
Industrial & Engineering Chemistry Research, 2013Co-Authors: Ignacio Julián, Javier Herguido, M MenendezAbstract:Effective particle circulation between the two zones is a prerequisite for ensuring the simultaneous reaction and Catalyst Regeneration inside a two-zone fluidized bed reactor (TZFBR). An appropria...
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stable steam reforming of ethanol in a two zone fluidized bed reactor
Industrial & Engineering Chemistry Research, 2012Co-Authors: L Perezmoreno, Javier Herguido, J Soler, M MenendezAbstract:The oxidative steam reforming of ethanol in a two-zone fluidized-bed reactor (TZFBR) and in a conventional fluidized-bed reactor over a Ni/Al 2 O 3 Catalyst has been investigated. Catalyst deactivation has been studied for both contact modes. Coke generation has been verified by several techniques, and a stable performance was obtained in the TZFBR, where coke formation was counteracted with continuous Catalyst Regeneration. The effects of the main operating variables (steam/ethanol ratio S/E, oxygen/ethanol ratio O/E, temperature, and relative velocity with respect to the minimum fluidization velocity) have been studied. Both stable results and continuous operation without Catalyst deactivation were achieved in the TZFBR in a wide range of S/E values, showing its viability for carrying out this process. High hydrogen selectivity with total conversion of ethanol was achieved even at low S/E and O/E ratios.
Javier Herguido - One of the best experts on this subject based on the ideXlab platform.
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pure hydrogen from biogas intensified methane dry reforming in a two zone fluidized bed reactor using permselective membranes
Chemical Engineering Journal, 2019Co-Authors: P. Duran, A Sanzmartinez, J Soler, M Menendez, Javier HerguidoAbstract:Abstract Methane dry reforming of biogas can be a sustainable source of hydrogen but the development of this technology is hindered by limitations such as endothermicity and Catalyst deactivation by coke. A two zone fluidized bed reactor coupling permselective Pd/Ag membranes counteracts them and allows to intensify the process obtaining a stable pure hydrogen production. Here we report the effect of operation variables (i.e., temperature, total bed height, nature and partial pressure of regenerative agent, relative height of the Regeneration and reaction zones, and use of an activation period) on the yield to hydrogen and stability of the process. Hydrogen over-yields, compared with the conventional fluidized bed reactor, in the range of +200% to +100% were obtained for the entire interval of temperatures 475–575 °C whilst maintaining stable operation by continuous Catalyst Regeneration. Around 70% of it was pure hydrogen coming from the permeate side of the membranes. The proposed reactor configuration greatly increases both methane conversion and selectivity to hydrogen (expressed as H2/CO ratio), not only in relation to our own conventional reactor findings but also regarding other published results.
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Table_1_Methane Aromatization in a Fluidized Bed Reactor: Parametric Study.DOCX
2019Co-Authors: Javier Lasobras, Javier Herguido, Miguel Menéndez, Jaime Soler, Alonso Jimenez, Mariana Da Silva, María J. Franco, Izaskun Barrio, Jesús LàzaroAbstract:Methane aromatization is a promising technology for the transformation of natural gas into liquid products, but suffers from the problem of Catalyst deactivation by coke. A two-zone fluidized bed reactor has been proposed as a tool to counteract the Catalyst deactivation, by providing continuous Catalyst Regeneration in the same vessel where the main reaction is carried out. This work shows the effect of the main operating conditions (carburization temperature, reaction temperature, carburization time, nature of regenerating agent and feed flow and height of the hydrocarbon entry point). Optimal reduction time and temperature were 1 h and 350°C. Best conversion and selectivity were achieved at 700°C without Catalyst deactivation in the TZFBR.
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Dry reforming of biogas in fluidized bed: Process intensification
International Journal of Hydrogen Energy, 2017Co-Authors: Paulina Ugarte, Maria Menendez, Javier Lasobras, Joaquim Soler, P. Duran, Javier HerguidoAbstract:Biogas is a renewable resource obtained mainly from the anaerobic fermentation of agro-industrial and anthropogenic residues. The production of hydrogen by dry reforming of methane represents a potential application for this renewable energy carrier. This could play a positive contribution towards meeting the challenge of providing a global supply of energetically sustainable and environmentally friendly energy. This work combines a catalytic reaction, a separation and the Catalyst Regeneration in a single reactor. To this end, a two zone fluidized bed reactor (TZFBR) with hydrogen selective membranes has been employed (TZFBR + MB). The operating conditions for the process of dry reforming of biogas have been optimized experimentally, both in TZFBR and TZFBR + MB. Several Catalysts were prepared (Ni/Al2O3, Ni–Ce/Al2O3, Ni–Co/Al2O3), characterized and tested in reactions in both TZFBR and in TZFBR + MB. Finally, the influence of using oxygen or carbon dioxide as regenerating gases in the process has been studied. Experimental results show the feasibility of using CO2 for in situ Catalyst Regeneration, avoiding the potential problems associated with the use of O2.
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stable hydrogen production by methane steam reforming in a two zone fluidized bed reactor experimental assessment
Journal of Power Sources, 2013Co-Authors: L Perezmoreno, Javier Herguido, J Soler, M MenendezAbstract:Abstract The Two Zone Fluidized Bed Reactor concept is proposed for hydrogen production via the steam reforming of methane (SRM) including integrated Catalyst Regeneration. In order to study the effect of the contact mode, the oxidative SRM has been carried out over a Ni/Al 2 O 3 Catalyst using a fixed bed reactor (fBR), a conventional fluidized-bed reactor (FBR) and the proposed two-zone fluidized bed reactor (TZFBR). The technical feasibility of these reactors has been studied experimentally, investigating their performance (CH 4 conversion, CO and H 2 selectivity, and H 2 global yield) and stability under different operating conditions. Coke generation in the process has been verified by several techniques. A stable performance was obtained in the TZFBR, where coke formation was counteracted with continuous Catalyst Regeneration. The viability of the TZFBR for carrying out this process with a valuable global yield to hydrogen is demonstrated.
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particle mixing in a two section two zone fluidized bed reactor experimental technique and counter current back mixing model validation
Industrial & Engineering Chemistry Research, 2013Co-Authors: Ignacio Julián, Javier Herguido, M MenendezAbstract:Effective particle circulation between the two zones is a prerequisite for ensuring the simultaneous reaction and Catalyst Regeneration inside a two-zone fluidized bed reactor (TZFBR). An appropriate degree of particle mixing provides a steady state catalytic operation, whereas poor solid circulation between the bed zones leads to unhampered Catalyst deactivation. To achieve effective control of the fluid dynamic regime within the two bed regions, a new design has been proposed with a different cross sectional area in each zone. The transition angle (α) between these zones represents the most characteristic feature of the so-called two-section TZFBR (TS-TZFBR). In the present study, the influence of operational variables (α, gas velocities, gas distributor location) on the particle circulation has been determined. Phosphorescent particles have been used as optical tracers to measure the solid axial mixing between the zones in a cold pseudo-2D TS-TZFBR facility. Additionally, a modified counter-current bac...
Ivan V Kozhevnikov - One of the best experts on this subject based on the ideXlab platform.
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sustainable heterogeneous acid catalysis by heteropoly acids
Handbook of Green Chemistry, 2010Co-Authors: Ivan V KozhevnikovAbstract:Heterogeneous acid catalysis by heteropoly acids (HPAs) has the potential for substantial economic and green benefits. The aim of this chapter is to discuss the perspectives of acid catalysis by solid HPAs, focusing in particular on several approaches that could help to achieve sustainable Catalyst performance. These approaches include developing novel HPA Catalysts possessing high thermal stability, modification of HPA Catalysts to enhance coke combustion, inhibition of coke formation on HPA Catalysts during operation and reactions in supercritical fluids and cascade reactions using multifunctional HPA catalysis. Keywords: heteropoly acid; heterogeneous acid catalysis; Catalyst Regeneration
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heterogeneous acid catalysis by heteropoly acids approaches to Catalyst deactivation
Journal of Molecular Catalysis A-chemical, 2009Co-Authors: Ivan V KozhevnikovAbstract:Heterogeneous acid catalysis by heteropoly acids (HPAs) has the potential of great economic rewards and green benefits. Its application, however, has been limited to some extent because of a relatively low thermal stability of HPAs, hence difficulty of Catalyst Regeneration (decoking). The aim of this paper is to discuss approaches to the problem of Catalyst deactivation that could be instrumental to achieve sustainable performance of solid HPA Catalysts. These approaches include: developing new HPA Catalysts possessing high thermal stability, modification of HPA Catalysts to enhance coke combustion, inhibition of coke formation on HPA Catalysts during operation, reactions in supercritical fluids and cascade reactions using multifunctional HPA catalysis.
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sustainable heterogeneous acid catalysis by heteropoly acids
Journal of Molecular Catalysis A-chemical, 2007Co-Authors: Ivan V KozhevnikovAbstract:Heterogeneous acid catalysis by heteropoly acids (HPAs) has the potential of substantial economic and green benefits. Its application, however, has been limited because of the difficulty of Catalyst Regeneration due to a relatively low thermal stability of HPAs. The aim of this paper is to discuss the perspectives of acid catalysis by solid HPAs, in particular focusing on several approaches that could help overcome the deactivation of HPA Catalysts to achieve sustainable Catalyst performance. These approaches include: developing novel HPA Catalysts possessing high thermal stability, modification of HPA Catalysts to enhance coke combustion, inhibition of coke formation on HPA Catalysts during operation, reactions in supercritical fluids and cascade reactions using multifunctional HPA catalysis.
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fries rearrangement of aryl esters catalysed by heteropoly acid Catalyst Regeneration and reuse
Applied Catalysis A-general, 2004Co-Authors: Elena F Kozhevnikova, Ezzat Rafiee, Ivan V KozhevnikovAbstract:Abstract Heteropoly acid H 3 PW 12 O 40 (PW) supported on silica and its salt Cs 2.5 H 0.5 PW 12 O 40 (CsPW), previously found as active solid acid Catalysts in the liquid-phase Fries rearrangement of aryl esters, have been studied for the rearrangement of phenyl acetate and naphthyl acetate in a batch reactor. During the reaction even in nonpolar solvents such as dodecane, PW leached from the silica support. No leaching was found for CsPW in polar (nitrobenzene) or nonpolar (dodecane) solvents. Significant coking was observed for the high-porous PW/SiO 2 (6–13 wt.% carbon), whereas the low-porous CsPW built only about 2 wt.% carbon. Both Catalysts could be separated by filtration and, after a simple workup (washing with dichloroethane), reused, albeit with reduced activity. The reusability of CsPW improved when the workup included air calcination at 350 °C, followed by steaming at 200 °C. Doping CsPW with Pd (ca. 2%) allowed full Regeneration of Catalyst activity and selectivity in phenyl acetate (PhOAc) rearrangement by the air calcination and steaming.
J Soler - One of the best experts on this subject based on the ideXlab platform.
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pure hydrogen from biogas intensified methane dry reforming in a two zone fluidized bed reactor using permselective membranes
Chemical Engineering Journal, 2019Co-Authors: P. Duran, A Sanzmartinez, J Soler, M Menendez, Javier HerguidoAbstract:Abstract Methane dry reforming of biogas can be a sustainable source of hydrogen but the development of this technology is hindered by limitations such as endothermicity and Catalyst deactivation by coke. A two zone fluidized bed reactor coupling permselective Pd/Ag membranes counteracts them and allows to intensify the process obtaining a stable pure hydrogen production. Here we report the effect of operation variables (i.e., temperature, total bed height, nature and partial pressure of regenerative agent, relative height of the Regeneration and reaction zones, and use of an activation period) on the yield to hydrogen and stability of the process. Hydrogen over-yields, compared with the conventional fluidized bed reactor, in the range of +200% to +100% were obtained for the entire interval of temperatures 475–575 °C whilst maintaining stable operation by continuous Catalyst Regeneration. Around 70% of it was pure hydrogen coming from the permeate side of the membranes. The proposed reactor configuration greatly increases both methane conversion and selectivity to hydrogen (expressed as H2/CO ratio), not only in relation to our own conventional reactor findings but also regarding other published results.
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stable hydrogen production by methane steam reforming in a two zone fluidized bed reactor experimental assessment
Journal of Power Sources, 2013Co-Authors: L Perezmoreno, Javier Herguido, J Soler, M MenendezAbstract:Abstract The Two Zone Fluidized Bed Reactor concept is proposed for hydrogen production via the steam reforming of methane (SRM) including integrated Catalyst Regeneration. In order to study the effect of the contact mode, the oxidative SRM has been carried out over a Ni/Al 2 O 3 Catalyst using a fixed bed reactor (fBR), a conventional fluidized-bed reactor (FBR) and the proposed two-zone fluidized bed reactor (TZFBR). The technical feasibility of these reactors has been studied experimentally, investigating their performance (CH 4 conversion, CO and H 2 selectivity, and H 2 global yield) and stability under different operating conditions. Coke generation in the process has been verified by several techniques. A stable performance was obtained in the TZFBR, where coke formation was counteracted with continuous Catalyst Regeneration. The viability of the TZFBR for carrying out this process with a valuable global yield to hydrogen is demonstrated.
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stable steam reforming of ethanol in a two zone fluidized bed reactor
Industrial & Engineering Chemistry Research, 2012Co-Authors: L Perezmoreno, Javier Herguido, J Soler, M MenendezAbstract:The oxidative steam reforming of ethanol in a two-zone fluidized-bed reactor (TZFBR) and in a conventional fluidized-bed reactor over a Ni/Al 2 O 3 Catalyst has been investigated. Catalyst deactivation has been studied for both contact modes. Coke generation has been verified by several techniques, and a stable performance was obtained in the TZFBR, where coke formation was counteracted with continuous Catalyst Regeneration. The effects of the main operating variables (steam/ethanol ratio S/E, oxygen/ethanol ratio O/E, temperature, and relative velocity with respect to the minimum fluidization velocity) have been studied. Both stable results and continuous operation without Catalyst deactivation were achieved in the TZFBR in a wide range of S/E values, showing its viability for carrying out this process. High hydrogen selectivity with total conversion of ethanol was achieved even at low S/E and O/E ratios.
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combination of a two zone fluidized bed reactor with a pd hollow fibre membrane for catalytic alkane dehydrogenation
Chemical Engineering Journal, 2009Co-Authors: Maria Pilar Gimeno, Javier Herguido, J Soler, M MenendezAbstract:Abstract The combination of a Pd hollow fibre membrane with a Two-Zone Fluidized Bed Reactor (TZFBR) is described for catalytic dehydrogenation of propane. This configuration aims to combine the in situ Catalyst Regeneration provided by the TZFBR with the increased conversion that can be achieved with a Pd membrane, which removes hydrogen from the reactor, thus enhancing the reaction rate and in theory allowing even higher than equilibrium conversion. The experiments show that the Pd hollow fibre membrane acts effectively removing hydrogen from the reaction media and that with a Pt–Sn/Al 2 O 3 Catalyst the TZFBR can achieve steady state operation in spite of the increased coking of the Catalyst. However, with this Catalyst the quicker coke formation caused by the removal of hydrogen outweighs the beneficial effect of hydrogen removal and the yield achievable for a given feed is lower in the presence of the membrane. A conclusion from these results is that a Catalyst with lower coke tendency is needed to apply this combination of Pd membrane and TZFBR.
Meng Li - One of the best experts on this subject based on the ideXlab platform.
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a promising approach to recover a spent scr Catalyst deactivation by arsenic and alkaline metals and Catalyst Regeneration
Chemical Engineering Journal, 2017Co-Authors: Meng Li, Xinran Wang, Xiaobin Yu, Shili Zheng, Hao Du, David Dreisinger, Yi ZhangAbstract:Abstract A large amount of spent selective catalytic reduction (SCR) Catalyst is generated annually. The spent SCR Catalyst is poisoned by arsenic and alkaline metals. These spent Catalysts also contain substantial amounts of heavy metals and are therefore considered as hazardous solid waste. In order to decontaminate the Catalysts from As, K and Na poisoning, recover the valuable metals (V and W) and regenerate the Catalysts, an efficient and green advanced oxidation process (AOPs) named oxidative ammonium bicarbonate leaching (OABL) at moderate temperature and ambient pressure was developed. The effect of the leaching parameters on the V, W, As, Na, K and Ti leaching efficiencies was investigated. The mechanisms of V5+ and W6+ species extraction process were investigated. Furthermore, the mechanism of extraction of the low valent As3+ was studied by ESR and a V4+ triggered Fenton-like reaction was proposed. The crystal structure of the Catalyst substrate anatase (TiO2) was not affected by the leaching process. After impregnation with active components, the activity of the regenerated SCR Catalyst was close to the level of the fresh Catalyst with an NO conversion of 91% at 400 °C. Therefore, this work has introduced a new method for efficient Regeneration of the spent Catalyst.