Hydrogen separation by ceramic membranes in coal gasification

Conference · Sun Nov 01 04:00:00 EST 1992

OSTI ID:10106799

Gavalas, G R

Table 1 lists the support tubes and the deposition reactants and other conditions used to prepare seven membranes. The permeances of these membranes immediately after deposition, after twelve hours of thermal treatment at 700--750{degrees}C, and after thirteen days of additional hydrothermal treatment at 550{degrees}C under 3 atm of water vapor are listed in Table 2. Figure 1 is an Arrhenius plot of the hydrogen permeance of membrane D25 (dimer reactant, 25 A pore support) before and after the hydrothermal treatment. The following conclusions can be drawn from the results of Tables 1 and 2. All membranes prepared in this series underwent hydrothermal treatment with the expected decrease of hydrogen permeance. Using the dimer and trimer precursors resulted in a slight improvement in hydrogen permeance and had no consistent effect on the H{sub 2}:N{sub 2} selectivity. Using the 25 {Angstrom} pore tubes improved moderately the hydrogen permeance but seemingly reduced the selectivity from about 500--1000 to about 200--300. The best permeance was obtained with membrane D25 made with 25 {Angstrom} pore size tubes using the dimer precursor. This tube had hydrogen permeance 0.13 Cm{sup 3}/Cm{sup 2}-min-atm and H{sub 2}:N{sub 2} selectivity of 200 at 500{degrees}C, after the thirteen-day hydrothermal treatment. It must be noted that the measurement of the very small nitrogen permeance is subject to considerable error, especially if there is some small leak in the system. Hence the true N{sub 2} permeances may be considerably lower than the measurements indicate, and the reported selectivities probably significantly underestimate the true selectivities. Figure 1 shows a sharp increase in the activation energy of hydrogen permeance following deposition and hydrothermal treatment.

• Research Organization: California Inst. of Tech., Pasadena, CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC21-90MC26365
• OSTI ID: 10106799
• Report Number(s): DOE/MC/26365--93/C0099; CONF-920951--14; ON: DE93002605
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105
ACTIVATION ENERGY
ARRHENIUS EQUATION
CERAMICS
CHEMICAL VAPOR DEPOSITION
COAL GASIFICATION
FABRICATION
FUEL GAS
GASIFICATION
HEAT TREATMENTS
HYDROGEN
MATERIALS RECOVERY
MEMBRANES
PERFORMANCE TESTING
SEPARATION PROCEDURES
SEPARATION PROCESSES
SILICON OXIDES
SPECIFICITY
TEMPERATURE DEPENDENCE
WATER VAPOR