pH-Regulated Refinement of Pore Size in Carbon Spheres for Size-Sieving of Gaseous C , C and C Hydrocarbon Pairs.

Selective separation of industrial important C , C and C hydrocarbon pairs by physisorbents can greatly reduce the energy intensity related to the currently used cryogenic distillation techniques. The achievement of size-sieving based on carbonaceous materials is desirable, but commonly hindered by the random structure of carbons often with a broad pore size distribution. Herein, a pH-regulated pre-condensation strategy was introduced to control the carbon pore architecture by the sp /sp hybridization of precursor. The lower pH value during pre-condensation of glucose facilitates the growth of aromatic nanodomains, rearrangement of stacked layers and a concomitant transition from sp -C to sp -C. The subsequent pyrolysis endows the pore size manipulated from 6.8 to 4.8 Å and narrowly distributed over a range of 0.2 Å. The refined pores enable effective size-sieving of C , C and C hydrocarbon pairs with high separation factor of 1.9 and 4.9 for C xylene (X) isomers para-X/meta-X and para-X/ortho-X, respectively, 5.1 for C alkane isomers n-hexane/3-methylpentane, and 22.0 for C H /C H . The excellent separation performance based-on size exclusion effect is validated by static adsorption isotherms and dynamic breakthrough experiments. This synthesis strategy provides a means of exploring advanced carbonaceous materials with controlled hybridized structure and pore sizes for challenging separation needs.