Hydrocarbon membrane types

Polyarylenes, in particular different types of poly(arylene ether ketone)s, have been the focus of much hydrocarbon membrane research in recent years. - - With good chemical and mechanical stability under PEM fuel cell operating conditions, the wholly aromatic polymers are considered to be the most promising candidates for high-performance PEM fuel cell applications. Many different types of these polymers are readily available and with good process capability. Some of these membranes are commercially available, such as poly(arylene sulfone)s and poly(arylene... 

Halwachs et al. studied the peimeation of hydrocaibons through oil-water-oil systems. They found that the most important variables governing the peimeation rates were membrane viscosity, type and concentration of surfactant, and ionic strength of the medium. However, the permeation rates of hydrocarbons through aqueous membranes were several orders of magnitude slower than the permeation rates of phenol through hydrocarbon membranes. ... 

Other waste streams, highly contaminated with lower molecular weight molecules, can also be hyperfiltered and concentrated by using alternate chemical membrane types.One example is the hyperfiltration of wastewater from certain oil refining operations containing significant amounts of benzene, toluene, ethylbenzene, and xylenes (BTEX), as well as other petroleum hydrocarbons. 

The first type of hydrocarbon membrane for fuel cell applications was the sulfonated polystyrene-divinylbenzene co-polymer membranes equipped for the power source in NASA s Gemini space flights, but the sulfonated polystyrene had low chemical stability for long-term applications, because the proton on the tertiary carbons and benzylic bonds are easily dissociated in an oxygen environment forming hydroperoxide radicals. Since a styrene monomer is easily co-polymerized with other vinyl monomers via radical polymerization methods, various styrenic polymers were researched intensively. Two commercial polystyrene-based/related membranes are available BAM (Ballard), and Dais Analytic s sulfonated styrene-ethylene-butylene-styrene (SEBS) membrane. Dais membranes are produced using... 

For hydrocarbon membranes, the degraded products can be directly measured owing to the stabihty of the carbon radicals. Fenton-type reaction on hydrocarbon model compounds has been smdied (Hubner and Roduner 1999). Possible weak sites for HO attack have been identified for various hydrocarbon ionomer membranes. 

Detailed discussions on the membrane chemical degradation mechanisms will first be divided into three main categories hydrocarbon membranes, g-PSSA membranes, and PFSA membranes. General degradation pathways and correlations between different types of membranes will be discussed at the end of this section. 

Abstract In this chapter, we discuss the proton conductivity and use of heteropoly acids (HP As) in proton exchange fuel cells. We first review the fundamental aspects of proton conduction in the HPAs and then review liquid HPA-based fuel cells. Four types of composite proton exchange membranes containing HPAs have been identified HPAs imbibed perfluorosulfonic acid membranes, HPAs imbibed hydrocarbon membranes, sol-gel-based membranes, and polymer hybrid polyoxometa-late (polypom)-based membranes. 

In Sittt Filter Membranes In situ membranes are being fitted into incinerator flue-gas stacks in an attempt to reduce hydrocarbon emissions. Two types of commercially available gas separation membranes are being stndied (I) flat cellnlose acetate sheets and (2) hoUow-tnbe fiber modules made of polyamides. 

Elydrocarbons of many different types are present in exliaust gas. In the presence of nitrogen oxide and sunlight, they form oxidants that irritate the mucous membranes. Some hydrocarbons are considered to be carcinogenic. Incomplete combustion produces unburned hydrocarbons. 

The mixed liposomal solutions were prepared by the ethanol-injection method(13) in order to obtain completely transparent solutions. It is interesting to note that miscibility of the photochromic amphiphiles with DPPC depend on the position of bulky azobenzene. If azobenzene is incorporated close to the end of long alkyl chain, a stable mixed bilayer state cannot be formed. On the other hand, when the azobenzene moiety is located near the head group or at the center of the hydrocarbon tail, the azobenzene amphiphiles are successfully incorporated into the bilayer membrane. No individual micelle formation nor phase separation in the bilayer was observed at 25 °C by absorption spectroscopy. However, the microstructure of the mixed liposomes depends on the type of azobenzene amphiphiles. 

The second part of the book covers zeolite adsorptive separation, adsorption mechanisms, zeolite membranes and mixed matrix membranes in Chapters 5-11. Chapter 5 summarizes the literature and reports adsorptive separation work on specific separation applications organized around the types of molecular species being separated. A series of tables provide groupings for (i) aromatics and derivatives, (ii) non-aromatic hydrocarbons, (iii) carbohydrates and organic acids, (iv) fine chemical and pharmaceuticals, (v) trace impurities removed from bulk materials. Zeolite adsorptive separation mechanisms are theorized in Chapter 6. 

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