Development of ceramic membrane reactors for high temperature gas cleanup

Conference · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7139320

Roberts, D L; Way, J D

The more difficult part of developing a membrane reactor was making a membrane with suitable permselectivity. Since both the ammonia and H[sub 2]S decomposition reactions produce H[sub 2], we want a membrane that selectively permeates hydrogen. We have taken the approach of coating a substrate that has fine pores (a microfilter or ultrafilter) with a completely dense layer and then (except for palladium coatings) malting super fine pores in the dense layer by leaching or pyrolysis. We used four different substrates (Norton 0.2 alumina monolith, Refractron alumina microfilters, Vycor glass, Alcoa ultrafilter) and five different coating materials (Poly N-methyl silazane, Aremco 617 alumina-based glaze, Polycyclohydridomethyl silazane, Aluminum phosphorus oxides, palladium). Only the palladium films on an alumina ultrafilter could be made regularly with a negligible defect population. The other approaches were plagued with cracks and poor reproducibility. We made palladium films on a tubular alumina ultrafilter (US Filter, Warrendale, PA) by electroless plating from a platinum amine complex solution in hydrazine (Rhoda, 1959). The best results were achieved with an ultrafilter pore size of 100 angstroms and with pretreatment of the surface in a stannic/stannous chloride solution. The films were about 5 microns thick and appeared defect free under electron microscopy. Because defect-free palladium films are infinitely selective to hydrogen with respect to the other components of gasifier product gas, we expect that the selectivity of our palladium films will exceed 1000 even with the inevitable defects that accompany real membranes. We have analyzed the performance and economics of membrane reactors for H[sub 2]S and NH[sub 3] decomposition using the reaction rates determined experimentally in our catalyst development work and using the permeation behavior of palladium films reported in the literature.

• Research Organization: SRI International, Menlo Park, CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC21-89MC26373
• OSTI ID: 7139320
• Report Number(s): DOE/MC/26373-93/C0104; CONF-920951-57; ON: DE93002824
• Resource Relation: Conference: US Department of Energy contractors review meeting on gasification and gas stream cleanup systems, Morgantown, WV (United States), 15-17 Sep 1992
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
GASES
HOT GAS CLEANUP
SEPARATION PROCESSES
MEMBRANES
PERMEABILITY
SPECIFICITY
ALUMINIUM OXIDES
AMMONIA
HYDROGEN SULFIDES
PALLADIUM
PERFORMANCE TESTING
SYNTHESIS GAS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
ELEMENTS
FLUIDS
HYDRIDES
HYDROGEN COMPOUNDS
METALS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
PURIFICATION
SULFIDES
SULFUR COMPOUNDS
TESTING
TRANSITION ELEMENTS
400105* - Separation Procedures