CO2/H2 separations

In summary, porous carbon-based materials for CO2 capture have experienced rapid development in the last several decades and will continue to blossom. The requirements of CO2 captures vary a lot depending on different processes, namely post-combustion (low pressure, predominantly CO2/N2 separation), pre-combustion (high pressure, predominantly CO2/H2 separation) capture and natural gas sweetening (predominantly CO2/CH4 separation). Thus, various kinds of new carbon materials with defined textural properties as well as tailored surface chemistry have been synthesized for a specific CO2 capture process. Another advantage lies... 

Membrane permeabilities for both CO2 and H2 and the CO2/H2 separation factor were evaluated in the presence of varying concentrations of CO (10,100,500ppm) in mixtures containing -20 mol% CO2, -20% H2, and a balance of Ar. Performance was also evaluated in the presence of varying concentrations of HjS (10, 100, 500ppm). 

R. Xing, W.S.W. Ho, Crosslinked polyvinylalcohol-polysiloxane/fumed siUca mixed matrix membranes containing amines for CO2/H2 separation. Journal of Membrane Science 367 (2011) 91-102. 

The concept of mixed-matrix membranes has been demonstrated at UOP ° in the mid-1980s using silicalite-cellulose acetate mixed-matrix membranes for CO2/H2 separation. In the demonstration, a feed mixture of 50/50 CO2/H2 with a differential pressure of 50 psi was used. The calculated separation factor for CO2/H2 was found to be 5.15 + 2.2. In contrast, a CO2/H2 separation factor of 0.77 + 0.06 was found for cellulose acetate membrane. This indicates that silicalite in the membrane phase reversed the selectivity from H2 to CO2. Experimental results and modeling predictions indicate that mixed-matrix membranes with the incorporation of fillers within polymeric substrates provide potential possibilities to achieve enhanced membrane performance, which will open up new opportunities for the separation and purification processes. Highlighted applications for mixed-matrix membranes include separation and purification of gas mixtures such as separation of N2 from CO2 removal from natural and separation... 

During the continuous reaction, alkene, CO, H2, and CO2 were separately fed into the reactor containing the ionic liquid catalyst solution. The products and uncon-... 

Furthermore, the application of the SOD membrane in a FT reaction has been investigated. The advantages of water removal in a FT reaction are threefold (i) reduction of H20-promoted catalyst deactivation, (ii) increased reactor productivity, and (iii) displaced water gas shift (WGS) equilibrium to enhance the conversion of CO2 to hydrocarbons [53]. Khajavi etal. report a mixture of H2O/H2 separation factors 10000 and water fluxes of 2.3 kg m h under... 

Carbon Dioxide-Methane Much of the natural gas produced in the world is coproduced with an acid gas, most commonly CO2 and/or H2S. While there are many successful processes for separating the gases, membrane separation is a commercially successful competitor, especially for small installations. The economics work best for feeds with very high or very low CH4 content. Methane is a slow gas CO2, H2S, and H2O are fast gases. 

The mole numbers per kg liquid for the gases (H2O, CO2, H2S, H2, and CH4) that separated from the condensate are obtained by multiplying the volume fraction of each by (7) the volume of gas per kg condensate, (2) the mass fraction Zvap of the vapor phase produced, and (3) the number of moles per liter of gas. The latter value can be calculated from the ideal gas law PV = R7k at 20 °C and 1 atm pressure, there are 0.0416 moles per liter of gas. The final values for each well,... 

Designed for CO2 removal after H2S is removed Simple operation Commercial overseas -used to remove CO2 after separate R2S removal 1,2,5... 

UOP Separex membrane comprising cellulose acetate (CA) polymer has been extensively used for CO2 removal from natural gas and currently holds the membrane market leadership for this appUcation. The UOP Polysep membrane, a polymeric membrane, has been successfully applied to H2 separation processes. 

Natural gas feedstock is very dependent of the source location in some cases it has high levels of H2S, CO2 and hydrocarbons. Organic sulfur compounds must be removed because they will irreversibly deactivate both reforming and WGS catalysts. Hence a preliminary feed desulfurization step is necessary. This process consists in a medium-pressure hydrogenation (usually on a cobalt-molybdenum catalyst at 290-370 °C), which reduces sulfur compounds to H2S, followed by H2S separation through ZnO adsorption (at 340-390 °C) or amine absorption [9]. 

The equilibria are readily reversed by heating and the salt loaded aqueous amine solutions can be made to release the carried H2S and CO2 after separation from the hydrocarbon gas being sweetened. 

Determining the effect of trace inorganic gases (H2O, CO2, H2S...) on the separation. 

Figure 7.11 Dual-membrane separation utilizing a highly selective metal or inorganic membrane for H2 purification and a conventional polymer membrane for the CO2/N2 separation.

The "Rectisol" or "Selexol" plant of the "selective" type absorbs both H S and C0 , but in the regeneration section of the plant the H S and CO are separated to provide two streams, one or which is CO, virtually free from H S, and the other is of a suitable CO2/H2S ratio to be processed in a conventional sulfur recovery plant. 

Jordal K, Bredesen R, Kvamsdal HM, and Bolland O. Integration of H2-separating membrane technology in gas turbine processes for CO2 capture. Energy 2004 29 1269-1278. 

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