Separation of Hydrogen and Carbon Dioxide

Listed in Table 7.6 are some studies of inorganic membranes for the separation of hydrogen from carbon dioxide. Alumina membranes with as fine as 10 to 20 nm pore diameter have been investigated and a maximum separation factor of only 5 has been obtained. Obviously, new membrane materials with more promising separation results are required before this application can be tackled by inorganic membranes. 

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Damle, A.S., Separation of Hydrogen and Carbon Dioxide in Advanced Fossil Energy Conversion Processes using a Membrane Reactor, 2002 Pittsburgh Coal Conference, Pittsburgh, PA, September 2002. 

Separation of hydrogen and carbon dioxide by inorganic membranes... 

Cao D, Wu J (2005) Modeling the selectivity of activated carbon for efficient separation of hydrogen and carbon dioxide. Carbon 43 1364-1370... 

Novel membranes for advanced, lower cost separations of hydrogen from carbon dioxide and other contaminants. 

Sircar, S. and Kratz, W.C. Simultaneous production of hydrogen and carbon dioxide from steam reformer off-gas, PSA. Separation Science and Technology, 1988, 23, 2397. 

In the shift conversion step, carbon monoxide reacts with steam to form equivalent amounts of hydrogen and carbon dioxide. Upon cooling of the effluent gas, most of the unreacted steam is condensed and separated as process condensate. Modem ammonia plants utilize a two-step, in-series shifting, carried out at high and then low temperatures to increase conversion efficiency. Use of the dual-shift conversion system lowers overall plant steam requirements, and the lower CO leakage results in reduction in plant feed requirements due to more complete conversion of CO to hydrogen. Under normal operating conditions there is no emission from the shift converters. 

The separation of oxygen from air is extremely important in connection with medical treatments, combustion processes, etc. Relatively thin effective membrane layers are required for practical oxygen separation systems, because the permeability coefficients of oxygen of most polymers are lower than those of hydrogen and carbon dioxide. 

In a system for separating gases, a tank containing a mixture of hydrogen and carbon dioxide is connected to a much larger tank where the pressure is kept very low. The two tanks are separated by a porous membrane through which the molecules must effuse. If the initial partial pressure of each gas is 5.00 atm, what will be the mole fraction of hydrogen in the tank after the partial pressure of carbon dioxide has declined to 4.50 atm (a) 52.1%, (b) 37.2%,... 

The Vision 21 program is focused on new concepts for coal-based energy production where modular plants could be configured to produce a variety of fuels and chemicals depending on market needs with virtually no environmental impact outside the plant s footprint. Membranes would be used to separate oxygen from air for the gasification process and to separate hydrogen and carbon dioxide from coal gas. 

The fluorine produced is either immediately used to prepare other final products or is first liquefied and delivered in steel cylinders where required. When fluorine is liquefied it is first led from the electrolyzer through a steel coil cooled to — 90 °C by dry ice. It then passes through a coil submerged in liquid oxygen, (— 183 °C) to separate the remaining traces of hydrogen fluoride, carbon dioxide and tetrafluoromethane. The product still contains a small... 

Hydrogen and Carbon Dioxide Production from Steam-Methane Reformer Off Gas Production of Ammonia Synthesis Gas Hydrogen Recovery fiom Refinery Off Gases Methane-Carbon Dioxide Separation from Landfill Gas... 

Derivation (1) Made almost pure by placing a mixture of oxygen and carbon dioxide in contact with incandescent graphite, coke, or anthracite. (2) Action of steam on hot coke or coal (water gas) or on natural gas (synthesis gas). In the latter case, carbon dioxide is removed by absorption in amine solution, and the hydrogen and carbon monoxide separated in a low-temperature unit. (3) By-product in chemical reactions. (4) Combustion of organic compound with limited amount of oxygen, as in automobile cylinders. (5) Dehydration of formic acid. 

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