Review Canada GIK 7P4This paper is an extensive review of the literature dealing with the class of catalytic membrane reactors which involves hydrogen permeable membranes made of palladium and palladium alloys. The fundamental factors which affect hydrogen permeability are first discussed. A classification of the many reactions which have been conducted in such reactors at both laboratory and commercial scales is then presented. The various techniques for the preparation of palladiumbased membranes are described and the literature on modeling and design of these reactors is also reviewed.Cet article passe en revue la littkrature relative B une classe de rkacteurs catalytiques z1 membranes utilisant des films de palladium ou d'alliages de palladium permtables a I'hydrogtne. On discute en premier lieu les facteurs qui affectent cette permeabilitk. On prCsente une classification des diverses rCactions et prockdes qui ont 6tC effectuCs dans de tels rtacteurs, au laboratoire et a I'kchelle commerciale. Les diverses techniques de prtparation des membranes 2 base de palladium sont dkcrites et on examine aussi la IittCrature portant sur la modClisation et la conception des rtacteurs.

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A series of composite membranes based on sulfonated polyether ether ketone with embedded powdered heteropolycompounds was prepared and their electrochemical and thermal properties were studied. An increase in degree of sulfonation as well as introduction of these fillers resulted in increased T g and enhanced membrane hydrophilicity, bringing about a substantial gain in proton conductivity. The conductivity of the composite membranes exceeded 10 −2 S/cm at room temperature and reached values of about 10 −1 S/cm above 100 • C.

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Biogas is a renewable energy source like solar and wind energies and mostly produced from anaerobic digestion (AD).

A series of sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymers were prepared by aromatic nucleophilic polycondensation of hexafluoroisopropylidene diphenol with 5,5′-carbonylbis(2-fluorobenzenesulfonate) and 4,4′-difluorobenzophenone (DFBP) at various molar ratios. The synthesized SPAEK-6F polymers possessed high molecular weights revealed by their high viscosity, and tough and flexible membranes were obtained by casting from DMAc solution. The sulfonate or sulfonic acid content (SC) of the polymers, expressed as a number per repeat unit of polymer, was determined by 1 H NMR spectroscopy and was in good agreement with the initial monomer ratios. The membranes exhibited increased water uptake and swelling with increasing SC and temperature. SPAEK-6F membranes with SC ranging from 0.6 to 1.14 maintained adequate mechanical strength after immersion in water at 80°C for 24 h. Fenton's reagent test revealed that the SPAEK-6F membranes had good stability to oxidation. The proton conductivities of the SPAEK-6F films increased with SC and temperature, reaching values above 3 × 10 -2 S/cm at 80°C for SC g 0.75. The tensile test indicated that the SPAEK-6F membranes with SC 0.75, 0.98, and 1.14 are tough and strong at ambient conditions. Consequently, these materials proved to be promising as proton exchange membranes and may be potentially useful for application in fuel cells operated at medium temperatures.

Comparative studies of membranes prepared using different solvents, have shown that the casting solvent plays a significant role, affecting their proton conductivity and mechanical strength. It has been found that using DMF strongly decreases the membrane conductivity in comparison with other solvents studied. The 1 H NMR results yield an insight into the mechanism of this effect, evidencing the formation of the strong hydrogen bonding of sulfonic acid groups with DMF. This can explain the large discordances of more than an order of magnitude existing between the conductivity results for sulfonated polyetheretherketone (PEEK) in some previous studies and in this work. It is also found that residual sulphuric acid, which is very difficult to eliminate from highly sulfonated polyetheretherketone (SPEEK), also affects its conductivity and under high temperature treatment, enters into reaction with both DMF and N,N-dimethylacetamide (DMAc), causing their degradation. As discussed in the present contribution, the conductivity measurement technique may also be a reason for discrepancy in the reported conductivity characteristics of SPEEK.