(478f) Fibrous Carbon Molecular Sieve with 3-5 a Tunable Pores for Many Industrial Gas Separations

Traditional adsorbents in the form of pellet/bead used in Pressure Swing Adsorption have significant constraint to balance the needs of high mass transfer rate and low pressure drop. Structured adsorbent, in the form of fiber, film, and honeycomb are desirable, which have large external contact area, small diffusion length, and low-resistance channels for gas flow. This talk introduces a new fibrous carbon molecular sieve adsorbent made by a two-step pyrolysis of melt extruded polyvinylidene chloride copolymer (PVDC) fiber. The PVDC fiber was first pretreated in air at low temperature (< 180 ⁰C) to form conjugated double bond and crosslinking via dehydrochlorination, then pyrolyzed in N₂ at high temperatures 1000-1400 ⁰C. A high throughput kinetic adsorption tool with 48 parallel testing cells using 10 probe molecules (from CO₂,σ_K=3.3 Ã… to SF₆,σ_K=5.5 Ã…) was used to 1) characterize the effective micropore size and its changes; and 2) fast screen the adsorbents for many industrial gas separations. The new fibrous CMS adsorbents have effective micropore size in the range of 3-5 Å and show very high separation factors of 20, 26, and 88 for the industrial gas pairs of N₂/CH₄, C₂H₄/C₂H₆, and C₃H₆/C₃H₈, respectively.