Gas separation using polymer membranes: an overview

“…The feed pressure was 600, 450 and 350 Torr, respectively, for consecutive measurements for all gases. The permeability coefficient P [cm 3 (STP) cm cm -2 s -1 cmHg -1 ] of single gas was determined as [32]:…”

Section: Gas Transport Propertiesmentioning

confidence: 99%

Stability of blended polymeric materials for CO2 separation

Lillepärg

Georgopanos

Shishatskiy

2014

Journal of Membrane Science

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Abstract:Blend materials of Pebax ® 1657 and low molecular weight poly(ethylene glycol)s were studied for their stability at temperature up to 90°C. It was found that a threshold of molecular weight exists at which leaching out of the low molecular weight compound from the polymer matrix becomes minimal. Poly(ethylene glycol) with methyl end groups having a molecular weight of 500 g/mol provides a blend material with a CO 2 permeability coefficient higher than in case of Polyactive™. PEBAX ® /DM500 blend can be a cheaper alternative to tailor made Polyactive™ in large scale production of thin film composite membrane.

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“…where N a is the steady-state gas flux through the membrane, is the membrane thickness, and " p 2 and p 1 are the feed (i.e., high) pressure and permeate (i.e., low) pressure, respectively (Ghosal and Freeman, 1994). In a gas mixture, p 2 and p 1 denote the partial pressures of component A on the high-and low-pressure sides of the membrane, respectively.…”

Section: Fundamentals Of Membrane Separationsmentioning

confidence: 99%

“…where D A is the effective concentration-averaged diffusivity (Ghosal and Freeman, 1994). The solubility coefficient, S A , is defined as C 2 /p 2 , where C 2 is the gas concentration in the polymer at the upstream face of the membrane.…”

Section: Fundamentals Of Membrane Separationsmentioning

confidence: 99%

Novel Technologies for Gaseous Contaminants Control

Turk¹,

Merkel²,

López-Ortíz³

et al. 2001

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The overall objective of this project is to develop technologies for cleaning/conditioning the syngas from an integrated gasification combined cycle (IGCC) system to meet the tolerance limits for contaminants such as H 2 S, COS, NH 3 , HCN, HCl, and alkali for fuel cell and chemical production applications. RTI's approach is to develop a modular system that (1) removes reduced sulfur species to sub-ppm levels using a hybrid process consisting of a polymer membrane and a regenerable ZnO-coated monolith or a mixed metal oxide sorbent; (2) removes hydrogen chloride vapors to sub-ppm levels using an inexpensive, high-surface area material; and (3) removes NH 3 with acidic adsorbents.RTI is working with MEDAL, Inc., and North Carolina State University (NCSU) to develop polymer membrane technology for bulk removal of H 2 S from syngas. These membranes are being engineered to remove the acid gas components (H 2 S, CO 2 , NH 3 , and H 2 O) from syngas by focusing on the "solubility selectivity" of the novel polymer compositions. The desirable components of the syngas (H 2 and CO) are maintained at high-pressure conditions as a non-permeate stream while the impurities are transported across the membrane to the low pressure side. RTI tested commercially available and novel materials from MEDAL using a high-temperature, high-pressure (HTHP) permeation apparatus. H 2 S/H 2 selectivities >30 were achieved, although there was a strong negative dependence with temperature. MEDAL believes that all the polymer compositions tested so far can be prepared as hollow fiber membrane modules using the existing manufacturing technology.For fuel cell and chemical applications, additional sulfur removal (beyond that achievable with the membranes) is required. To overcome limitations of conventional ZnO pellets, RTI is testing a monolith with a thin coating of high surface area zinc-oxide based materials. Alternatively, a regenerable sorbent developed by DOE/NETL (RVS-1) is being evaluated for this application. A multi-cycle test of 2-in. (5-cm) diameter monolith samples demonstrated that <0.5 ppm sulfur can be achieved.Removal of HCl vapors is being accomplished by low-cost materials that combine the known effectiveness of sodium carbonate as an active matrix used with enhanced surface area supports for greater reactivity and capacity at the required operating temperatures. RTI is working with SRI International on this task. Sorbents prepared using diatomaceous earth and sepiolite, impregnated with sodium carbonate achieved steady-state HCl level <100 ppb (target is 10 ppb). Research is continuing to optimize the impregnation and calcination procedures to provide an optimum pore size distribution and other properties.RTI and SRI International have established the feasibility of a process to selectively chemisorb NH 3 from syngas on high surface area molecular sieve adsorbents at high temperatures by conducting a series of temperature-programmed reactions at 225C (437F). Significant levels of NH 3 were adsorbed on highly acidic ads...

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Gas separation using polymer membranes: an overview

Cited by 517 publications

References 74 publications

Elucidation on the Effect of Operating Temperature to the Transport Properties of Polymeric Membrane Using Molecular Simulation Tool

Elucidation on the Effect of Operating Temperature to the Transport Properties of Polymeric Membrane Using Molecular Simulation Tool

Stability of blended polymeric materials for CO2 separation

Novel Technologies for Gaseous Contaminants Control

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