Examinando por Autor "Bilbao, J."

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High-Purity Green Hydrogen Production by Bio-oil/Ethanol Mixtures Steam Reforming in Pd-Based Membrane Reactors
(AIDIC, The Italian Association of Chemical Engineering, 2023-06-30) Iglesias-Vázquez, S.; Valecillos, J.; Remiro, A.; Landa, L.; Alique, D.; Santos-Carballes, A.J.; Sanz, R.; Calles, J.A.; Bilbao, J.; Gayubo, A.G.
The use of a membrane reactor (MR) for the reforming of biomass derived oxygenates is a promising approach to produce pure hydrogen from renewable sources. In this study, a Pd membrane supported on a porous stainless-steel (PSS) tube was fabricated by Electroless Pore Plating (ELP- PP) and tested in the steam reforming (SR) of bio-oil stabilized with 25 wt.% ethanol. All reaction tests were conducted in a reaction setup with two consecutive steps: (i) the thermal treatment for the vaporization of the bio-oil/ethanol mixture and the controlled deposition of pyrolytic lignin, and (ii) the SR reaction in an upwards-flow bed reactor with a Ni-based catalyst obtained upon reduction of a NiAl2O4 spinel. The Pd membrane was allocated in the middle of the SR reactor for its use as a MR. The reaction conditions were maintained at 580 °C with steam/carbon ratio of 2.5, space time of 0.15 h, feed pressure in the range of 1-3.3 bar, 0.1 bar in the permeate side, and time on stream of 4 h. The results reveal the enhancement of the hydrogen yield when using the MR at 3.3 bar and with the lowest gas velocity, allowing a hydrogen recovery of 57.74% with 99.8% purity. Consequently, the total hydrogen production in the MR operating at 3.3 bar and 0.6 cm s-1 increased from 0.309 to 0.367 g H2 (g C)-1 if compared to the conventional reactor at 1 bar and 0.9 cm·s-1.
Steam reforming of bio-oil stabilized with ethanol over a Ni/MgAl2O4 catalyst in a Pd-membrane reactor
(Elsevier, 2025-07-07) Iglesias-Vázquez, S.; Valecillos, J.; Remiro, Aingeru; Elordi, Gorka; Alique, D.; Santos-Carballes, A.J.; Sanz, R.; Calles, J.A.; Bilbao, J.; Gayubo, A.G.
A new membrane reactor (MR) has been used in the steam reforming (SR) of a feed of raw bio-oil stabilized with 25 wt% ethanol over a Ni/MgAl2O4 catalyst, comparing the results (yield of H2 and byproduct gases) to those reached in a conventional reactor (CR). The reaction setup involves two steps in series: a down-flow tube (at 500 ºC) for the vaporization of the feed and controlled removal of pyrolytic lignin (PL) from the oxygenates in the biooil, followed by an up-flow reactor provided with a composite Pd membrane supported on a porous stainless steel (PSS) tube containing a CeO2 intermediate layer (Pd/CeO2/PSS). In the MR configuration (with permeate pressure of 0.2 bar absolute), a H2 yield of 82 % was achieved at 550 ºC, space time of 2.8 h, S/C ratio of 1.55 and 3 bar in the retentate (reactor). This result significantly improves those reached in CR, even at 1 bar and 600 ºC. The S/C ratio in the feed must be limited in the MR configuration to avoid restrictions in H2 flux through the Pdmembrane caused by a higher gas dilution and concentration-polarization effect, as observed when the S/C ratio is increased up to 2.2. Similarly, a higher retentate pressure has a negative effect on the H2 yield due to its negative impact on the equilibrium of methane SR, that overcomes its benefits on the H2 permeation through the membrane. A promising performance of the membrane and catalyst has been obtained, thus demonstrating good prospects for their use in the sustainable production of H2 from lignocellulosic biomass