One-step solvent-free approach to constructing microporous BCNO to enhance adsorptive desulfurization

Abstract

Construction of structurally stable and highly porous materials, like hexagonal boron nitride (h-BN), is a prerequisite for achieving efficient adsorptive desulfurization (ADS). Nevertheless, the present constraints in precisely adjusting the pore structure parameters of BN impede its further utilization in the field of adsorption. In this study, highly porous boron carbon oxynitride (BCNO) adsorbents were synthesized via a straightforward, one-step solvent-free reaction. By modifying the composition of nitrogen (N) precursors, it was possible to finer tuning the micropore ratio thereby leading to a substantial increase in micropore surface area. Moreover, the fitting coefficients (R2) between Smicropore, Vmicropore, and adsorption capacity are 0.81959 and 0.80547, indicating a strong correlation between the microporous structure and the ADS performance. The prepared BCNO-UM6:4 adsorbent showed excellent adsorption performance with a capacity of 47.2 mg S/g adsorbent, surpassing the adsorbents synthesized using solvent-based methods (39.4 mg S/g adsorbent) and single-source N synthesis (BCNO-U18 32.1 mg S/g adsorbent, BCNO-M6 12.1 mg S/g adsorbent). Experimental results revealed that the main adsorption mechanism is multi-layer adsorption by the micropore filling. Density functional theory (DFT) revealed that the newly formed S-N covalent bonds and C-H···N hydrogen bonds are the main driving forces. In summary, this synthetic method expands the production pathway of porous BCNO and has potential application in various research fields.