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In this work, we developed a new preparation technique for palladium composite membranes which re... more In this work, we developed a new preparation technique for palladium composite membranes which results in an ultra-thin and defect-free selective layer with outstanding performance properties and long life. In the method, a palladium precursor and a reducing agent on opposite sides of a substrate of porous alumina hollow fibers were placed and used an electric field to cause migration of metal ions to the outer surface where they are reduced to form seeds at high concentration in a narrow spatial region. The ethanol steam reforming was conducted in a membrane reactor with the Pd membrane and the performance of this reactor was compared with results from a packed bed reactor under identical conditions. For all conditions studied, enhancement of ethanol conversion and hydrogen yield were observed in the membrane reactor compared to the packed bed reactor.
This thesis describes a new technique for the preparation of ultrathin Pd based membranes support... more This thesis describes a new technique for the preparation of ultrathin Pd based membranes supported on a hollow-fiber α-alumina substrate for H2 separation. The effectiveness of the membranes is demonstrated in the ethanol steam reforming (EtOH SR) reaction in a membrane reactor (MR) for H2 production. The membrane preparation technique uses an electric-field to uniformly deposit Pd nanoparticle seeds on a substrate followed by deposition of Pd or Pd-Cu layers on the activated surface by electroless plating (ELP). The well distributed Pd nanoparticles allow for enhanced bonding between the selective layer and the substrate and the formation of gas tight and thermally stable Pd or Pd-Cu layers as thin as 1μm, which is a record in the field. The best Pd membrane showed H2 permeance as high as 5.0 × 10 -6 mol m -2 s -1 Pa -1 and stable H2/N2 selectivity of 9000 7000 at 733 K for 5days. The Pd-Cu alloy membrane showed H2 permeance of 2.5 × 10 -6 mol m -2 s -1 Pa -1 and H2/N2 selectivity...
Reaction Kinetics and Catalysis Letters, 2001
Journal of Membrane Science, Jun 1, 2011
Journal of Membrane Science, Mar 1, 2011
Journal of Membrane Science
The ethanol steam reforming (EtOH SR) reaction was carried out over a Co–Na/ZnO catalyst both in ... more The ethanol steam reforming (EtOH SR) reaction was carried out over a Co–Na/ZnO catalyst both in a packed bed reactor (PBR) and in membrane reactors (MRs) equipped with ultrathin Pd or Pd–Cu membranes to evaluate the benefits of employing membranes. For all conditions, ethanol conversion and hydrogen production were significantly higher in the MRs than in the PBR. Average ethanol conversion enhancement and hydrogen production enhancement were measured to be 12% and 11% in the Pd MR and 22% and 19% in the Pd–Cu MR, respectively. These enhancements of the conversion and product yield can be attributed to the shift in equilibrium by continuous hydrogen removal by the Pd based membranes. A significant contamination of the Pd layer by CO or carbon compounds during the reaction can be the reason for the comparatively low enhancement in the Pd MR compared to the Pd–Cu MR in spite of the high H2 permeability of the original Pd membrane. A one-dimensional modeling study of the MRs and the PB...
Journal of Membrane Science, 2011
Journal of Membrane Science, 2014
In this work, we developed a new preparation technique for palladium composite membranes which re... more In this work, we developed a new preparation technique for palladium composite membranes which results in an ultra-thin and defect-free selective layer with outstanding performance properties and long life. In the method, a palladium precursor and a reducing agent on opposite sides of a substrate of porous alumina hollow fibers were placed and used an electric field to cause migration of metal ions to the outer surface where they are reduced to form seeds at high concentration in a narrow spatial region. The ethanol steam reforming was conducted in a membrane reactor with the Pd membrane and the performance of this reactor was compared with results from a packed bed reactor under identical conditions. For all conditions studied, enhancement of ethanol conversion and hydrogen yield were observed in the membrane reactor compared to the packed bed reactor.
This thesis describes a new technique for the preparation of ultrathin Pd based membranes support... more This thesis describes a new technique for the preparation of ultrathin Pd based membranes supported on a hollow-fiber α-alumina substrate for H2 separation. The effectiveness of the membranes is demonstrated in the ethanol steam reforming (EtOH SR) reaction in a membrane reactor (MR) for H2 production. The membrane preparation technique uses an electric-field to uniformly deposit Pd nanoparticle seeds on a substrate followed by deposition of Pd or Pd-Cu layers on the activated surface by electroless plating (ELP). The well distributed Pd nanoparticles allow for enhanced bonding between the selective layer and the substrate and the formation of gas tight and thermally stable Pd or Pd-Cu layers as thin as 1μm, which is a record in the field. The best Pd membrane showed H2 permeance as high as 5.0 × 10 -6 mol m -2 s -1 Pa -1 and stable H2/N2 selectivity of 9000 7000 at 733 K for 5days. The Pd-Cu alloy membrane showed H2 permeance of 2.5 × 10 -6 mol m -2 s -1 Pa -1 and H2/N2 selectivity...
Reaction Kinetics and Catalysis Letters, 2001
Journal of Membrane Science, Jun 1, 2011
Journal of Membrane Science, Mar 1, 2011
Journal of Membrane Science
The ethanol steam reforming (EtOH SR) reaction was carried out over a Co–Na/ZnO catalyst both in ... more The ethanol steam reforming (EtOH SR) reaction was carried out over a Co–Na/ZnO catalyst both in a packed bed reactor (PBR) and in membrane reactors (MRs) equipped with ultrathin Pd or Pd–Cu membranes to evaluate the benefits of employing membranes. For all conditions, ethanol conversion and hydrogen production were significantly higher in the MRs than in the PBR. Average ethanol conversion enhancement and hydrogen production enhancement were measured to be 12% and 11% in the Pd MR and 22% and 19% in the Pd–Cu MR, respectively. These enhancements of the conversion and product yield can be attributed to the shift in equilibrium by continuous hydrogen removal by the Pd based membranes. A significant contamination of the Pd layer by CO or carbon compounds during the reaction can be the reason for the comparatively low enhancement in the Pd MR compared to the Pd–Cu MR in spite of the high H2 permeability of the original Pd membrane. A one-dimensional modeling study of the MRs and the PB...
Journal of Membrane Science, 2011
Journal of Membrane Science, 2014