scholarly journals Separating Hydrogen From Coal Gasification Gases With Alumina Membranes

1992 ◽  
Vol 114 (2) ◽  
pp. 367-370 ◽  
Author(s):  
B. Z. Egan ◽  
D. E. Fain ◽  
G. E. Roettger ◽  
D. E. White
Keyword(s):  
Carbon Dioxide ◽  
Coal Gasification ◽  
Process Development ◽  
Porous Alumina ◽  
Mean Value ◽  
Knudsen Flow ◽  
Gasification Process ◽  
Alumina Membranes ◽  
Separation Factors ◽  
Membrane Permeabilities

Synthesis gas produced in coal gasification processes contains hydrogen, along with carbon monoxide, carbon dioxide, hydrogen sulfide, water, nitrogen, and other gases, depending on the particular gasification process. Development of membrane technology to separate the hydrogen from the raw gas at the high operating temperatures and pressures near exit gas conditions would improve the efficiency of the process. Tubular porous alumina membranes with mean pore radii ranging from about 9-22 Å have been fabricated and characterized. Based on the results of hydrostatic tests, the burst strength of the membranes ranged from 800-1600 psig, with a mean value of about 1300 psig. These membranes were evaluated for separating hydrogen and other gases. Tests of membrane permeabilities were made with helium, nitrogen, and carbon dioxide. Measurements were made at room temperature in the pressure range of 15-589 psi. In general, the relative gas permeabilities correlated qualitatively with a Knudsen flow mechanism; however, other gas transport mechanisms such as surface adsorption also may be involved. Efforts are under way to fabricate membranes having still smaller pores. At smaller pore sizes, higher separation factors are expected from molecular sieving effects.

scholarly journals Separating Hydrogen From Coal Gasification Gases With Alumina Membranes

1991 ◽  
Author(s):  
B. Z. Egan ◽  
D. E. Fain ◽  
G. E. Roettger ◽  
D. E. White
Keyword(s):  
Carbon Dioxide ◽  
Coal Gasification ◽  
Process Development ◽  
Porous Alumina ◽  
Mean Value ◽  
Knudsen Flow ◽  
Gasification Process ◽  
Alumina Membranes ◽  
Separation Factors ◽  
Membrane Permeabilities

Synthesis gas produced in coal gasification processes contains hydrogen, along with carbon monoxide, carbon dioxide, hydrogen sulfide, water, nitrogen, and other gases, depending on the particular gasification process. Development of membrane technology to separate the hydrogen from the raw gas at the high operating temperatures and pressures near exit gas conditions would improve the efficiency of the process. Tubular porous alumina membranes with mean pore radii ranging from about 9 to 22 A have been fabricated and characterized. Based on the results of hydrostatic tests, the burst strength of the membranes ranged from 800 to 1600 psig, with a mean value of about 1300 psig. These membranes were evaluated for separating hydrogen and other gases. Tests of membrane permeabilities were made with helium, nitrogen, and carbon dioxide. Measurements were made at room temperature in the pressure range of 15 to 589 psi. In general, the relative gas permeabilities correlated qualitatively with a Knudsen flow mechanism; however, other gas transport mechanisms such as surface adsorption may also be involved. Efforts are under way to fabricate membranes having still smaller pores. At smaller pore sizes, higher separation factors are expected from molecular sieving effects.

Immobilization of Calcium Oxide Absorbent on a Fibrous Alumina Mat for High Temperature Carbon Dioixde Capture

2008 ◽  
Author(s):  
Man Su Lee ◽  
D. Yogi Goswami ◽  
Nikhil Kothurkar ◽  
Elias K. Stefanakos
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Calcium Oxide ◽  
Power Plants ◽  
Coal Gasification ◽  
Carbon Dioxide Emission ◽  
Oxide Content ◽  
Gasification Process ◽  
Cyclic Operation ◽  
Number Of Cycles

Anthropogenic carbon dioxide emission from its sources must be reduced to decrease the threat of global warming. Calcium oxide is considered as an effective carbon dioxide absorbent in biomass or coal gasification process as well as conventional power plants. It reacts with carbon dioxide to form calcium carbonate which can be decomposed into the original oxide and carbon dioxide at high temperature by calcination. In order to make this method practical for the carbon dioxide capture and sequestration, the performance of the calcium oxide absorbent must be maintained over a large number of carbonation/calcination cycles. For this reason, loss in the surface area of the absorbent due to pore plugging and sintering of particles in cyclic operation must be avoided. To prevent or minimize this problem, a simple and effective procedure for immobilization of calcium oxide on a fibrous alumina mat was developed in this study. The prepared samples were observed by SEM and the cyclic performance of the calcium oxide absorbent was evaluated by TGA experiments and compared to the previous studies in literature. 75% and 62% maximum carbonation conversions of the prepared absorbents with 23 wt % and 55 wt % calcium oxide content were achieved respectively and remained stable even after ten cycles whereas conversion in the literature data dropped steeply with the number of cycles.

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