Palm Sheath–Derived Porous Carbon for Gas Separation


Pressure swing adsorption (PSA) processes using solid adsorbents are considered promising for CO2 adsorption and gas separation owing to its economic feasibility, high energy efficiency, and operational practicality. Performance of PSA processes are mainly determined by the adsorbents, which are commonly porous solid materials such as activated carbons (ACs), zeolites, and metal-organic frameworks (MOFs). Among these materials, AC is one of the most studied and highly regarded for industrial applications. However, pristine AC often contends with low gas selectivity with poor adsorption capacities. To counter this, chemically doping heteroatoms into carbon frameworks may enhance the adsorbent performance and selectivity by altering physical and chemical surface properties.

Biomass is a promising precursor for porous carbon, especially with industry focus on low cost and sustainability. Palms are a widely distributed plant with ornamental, greening, and economic advantages. However, palm sheath, which consists of crossed fibers of different diameters, is of limited utility and considered silviculture waste. Nonetheless, palm sheath fiber is a multicellular fiber with numerous hollow sieve tubes, suggesting potential for gas adsorption applications. 

Invention Description
Researchers at Arizona State University have developed novel N- and O-rich porous carbons prepared by a simple one-step NaNH2 activation of palm sheath at 350–550°C for highly selective separation of CO2/N2, CO2/CH4, and CH4/N2. The pore size distribution, Brunauer-Emmett-Teller (BET) surface area, and oxygen/nitrogen ratios in the material can be readily tuned by controlling the reaction conditions which determines the gas uptake and selectivity properties. The carbons showed CO2 uptake capacities of up to 5.78 mmol/g at 1.0 bar pressure and 273 K which is superior to many common carbon-based and metal-organic framework (MOF) CO2 adsorbents. Due to the high surface area and ultra-micropores, as well as moderate polar group ratio, the as-prepared porous carbon exhibited CO2/N2, CO2/CH4, and CH4/N2 selectivities of 107, 10.7, and 7.6 at 298 K and 1.0 bar, respectively.

Potential Applications
•  Carbon capture
•  Gas separation and purification

Benefits and Advantages
•  Readily tunable gas uptake and selectivity properties 
•  Outperforms common carbon-based and metal-organic framework (MOF) CO2 adsorbents
•  Makes use of waste biomass

Related Publication: Facile preparation of N and O-rich porous carbon from palm sheath for highly selective separation of CO2/CH4/N2 gas-mixture

Research Homepage of Professor Shuguang Deng

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Shuguang Deng Fan Liu

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