Functional Hollow Fiber Adsorbent Materials with a Self-Regulating Composite Outer Layer for Gas Purification with Energy Efficient Electrothermal Regeneration

Hollow fiber adsorbents have potential to overcome high pressure drop, adsorbent bed settling, and channeling problems in fixed bed adsorption systems. A coaxial spinning method was used for the synthesis of hollow fibers with an outer layer of electrically conducting polyvinylidene fluoride/carbon black composite with a positive temperature coefficient of resistivity and an inner layer of zeolite 13X/polyethersulphone adsorbent. The outer layer was optimized for self-limiting/regulating alternating current (AC) electrothermal regeneration. A fiber cartridge was constructed for studying the dynamic breakthrough and adsorbent regeneration characteristics. The breakthrough results for water vapor adsorption were analyzed by Wheeler-Jonas, Linear Driving Force (LDF) and Richards sigmoidal models. The isosteric enthalpy and kinetics for adsorption were determined for static vapor adsorption. The LDF adsorption kinetics observed at low surface coverage change to a stretched exponential kinetic model with increasing surface coverage. Intraparticle diffusion in the zeolite crystalline porous structure was rate-determining for water vapor breakthrough characteristics.