Hydrogen Selective Membranes
(September, 1998 - February, 2001)
Publications and Presentations
Hydrogen utilized in a fuel cell is considered a clean and renewable source of fuel. Recently, it has been demonstrated that hydrogen based fuel cell is both practical and economical for both stationary application and transportation. Hong Kong's geography and localized urban population makes it an excellent testing ground for fuel cell technology. Efficient hydrogen production from local Towngas and by reforming of methane can be achieved using Pd-based membranes. However, the cost of palladium can be prohibitive. This research focuses on developing synthesis technology for the preparation of ultra-thin palladium membranes that have superior thermal and chemical stability under operating conditions [29]. Alloying with metals such as silver was employed to improve the membrane tolerance for low temperature operation and to enhance its permeation flux [30-33]. Alloying with less expensive metals also reduces the cost of the membrane.
HKUST6029/98P Palladium alloy membranes for hydrogen separation and production.
PRINCIPAL INVESTIGATOR: King Lun Yeung
STATUS: Completed
SUMMARY: The exact conditions for deposition of pure palladium and pure silver membranes as well as simultaneous, co-deposition of palladium and silver have been identified for a hydrazine-based plating bath containing both palladium and silver precursors. The electroless plating kinetics have been determined for co-deposition of palladium and silver from the mixed plating bath. A mathematical model has been developed to predict the film thickness, plating rate and composition profile as a function of plating parameters (i.e., reactant concentrations and time). The evolution of the microstructure and composition of the film during electroless plating have also been investigated. A hydrogen permeation study has demonstrated that the Pd-Ag alloy membrane has performance superior to that of a pure palladium membrane of similar thickness. In addition, the formation of a single-phase alloy results in substantial enhancement in the hydrogen permeation rate. High purity hydrogen (> 99 %) production was achieved using Towngas as feedstock.
Students: (1 M. Phil. student, 1 M. Sc. student)
Ms. Yuen Shan Cheng (Jr. R.A., June-August, 1997; part time Jr. R.A., August, 1997 - May, 1998; M. Phil. student, September, 1998 - February, 2001; Research Assistant, February - May, 2001)
Mr. Kwong Fai Cheung (M. Sc. student, September, 2000 - present)
Publications and Presentations: (5 peer-reviewed journal manuscripts, 3 presentations)
K. L. Yeung, S. Christiansen and A. Varma, "Palladium composite membranes prepared by electroless plating: Relationships between plating kinetics, film microstructure and membrane permeation," J. Membr. Sci., 159 (1999) 107.
Y.S. Cheng and K.L. Yeung, "Palladium-silver composite membranes by electroless plating technique," J. Membr. Sci., 158 (1999) 127. PDF file
Y.S. Cheng and K.L. Yeung, "Effects of electroless plating chemistry on the synthesis of palladium membranes," J. Membr. Sci., 182 (2001) 195.
Y.S. Cheng, M.A. Peña, J.L. Fierro, D.C.W. Hui and K.L. Yeung , "Performance of alumina, zeolite, palladium, Pd-Ag alloy membranes for hydrogen separation from towngas mixture," J. Membr. Sci. 204 (2002) 329-340.
A. Varma, K.L. Yeung, R. Souleimanova, A. Mukasyan," Novel approach for thin dense nanoscale-grained metal films, " Ind. & Eng. Chem. Res., 41 (2002) 6323-6325.
Conferences and Invited Talks:
Y.S. Cheng and K.L. Yeung, "Palladium-Silver composite membranes by electroless plating technique synthesis, characterization and separation properties," Sixth International Conference on Inorganic Membranes at Montpellier, France, June 26-30, 2000.
Y.S. Cheng, C. Tellez, M.A. Pena, A. Varma and K.L. Yeung, "Ethylene epoxidation in a packed bed membrane reactor: Effects of oxygen partition and feedthrough design," 4th International Conference on Catalysis in Membrane Reactors at Zaragoza, Spain, July 3-5, 2000.
C. Tellez, Y.S. Cheng, C.W. Hui and K.L. Yeung, "Performance of a packed bed membrane reactor for ethylene epoxidation: Experimental results and model prediction," 4th International Conference on Catalysis in Membrane Reactors at Zaragoza, Spain, July 3-5, 2000.
