Carbon Fiber Composite Molecular Sieves for Gas Separation

Abstract

IntroductionCarbon fibers are produced commercially from rayon, phenolics, polyacrylonitrile (PAN), or pitch. The last are further divided into fibers produced from isotropic pitch precursors, and those derived from pitch that has been pretreated to introduce a high concentration of carbonaceous mesophase. Over the past few decades, interest in research and manufacturing carbon fibers has overwhelmingly centered on producing fibers with high tensile strength and high modulus for lightweight, high performance composites, where polymers, metals, and carbon can form the continuous matrix. The fibers most commonly used in advanced materials are produced from PAN or mesophase pitch. Graphitized mesophase pitch fibers tend to have higher modulus and lower tensile strength than the PAN-based equivalents. They have advantages in applications requiring high stiffness, high electrical and thermal conductivity, low thermal expansion, and high temperature oxidation resistance, while PAN fibers are employed where high strength is required.

Post combustion CO2 capture by carbon fibre monolithic adsorbents

“…One problem, non-uniform activation, arises when using steam or CO 2 for activation. This has been reported by some researchers [54,56]. Researchers have observed that BET surface area and micropore volume vary at different locations in the samples.…”

“…The chemisorption and activation steps were repeated until the desired burn-off was attained (8.5-13.4%). Under favourable conditions, the range of variation of surface area was about 3-6% [56,119]. The only problem with this technique is that the reaction time is much longer than with the conventional methods.…”

“…Recently, gas adsorption by activated carbon fibres and carbon fibre composites has been identified as a promising alternative. Lately, structured porous monolith materials made from carbon fibres, which have the ability to selectively adsorb gases due to their molecular sieving characteristics, have been investigated [52][53][54][55][56][57][58][59][60][61][62][63]. Carbon fibre composite in monolith form reduce inter-particle voids and maximize bulk density, thereby increasing the adsorption capacity of the material.…”

“…Researchers have observed that BET surface area and micropore volume vary at different locations in the samples. In attempting to solve this problem, Jagtoyen and his colleagues [56] developed another configuration for the supply of activation agents within the activation furnace to reduce variations in the concentration of the agent. Nevertheless, this was able to only partially alleviate the problem.…”

Investigating the Effect of Carbon Shape on Virus Adsorption

“…No abrasion can occur in the composites, and the amount of carbon fines released into the treated water is expected to be very low (). A proprietary process makes ACFCs from carbon fibers that have been joined into a composite and activated to introduce porosity ( , ). The composites have relatively uniform pore distributions and surface areas comparable to commercial GAC ().…”