Synthesis, characterization and adsorptive denitrogenation performance of bimodal mesoporous Ti-HMS/KIL-2 composite: A comparative study on synthetic methodology

•Mesoporous silicates Ti-HMS and KIL-2 as structural components for constructing hierarchical composites.•Two-step and dual-template comparatively synthesis for Ti-HMS/KIL-2.•Bimodal distribution of pore size and regulable larger mesopores for Ti-HMS/KIL-2.•Improved hydrothermal stability and recyclability for adsorptive removal of NCCs.

Novel titanosilicate composites with bimodal mesopores using molecular sieves Ti-HMS and Ti-KIL-2 as structural components were successfully synthesized by two-step and dual-template methods in a comparative study. The as-synthesized Ti-HMS/KIL-2 samples were characterized by a series of techniques including X-ray diffraction, UV-vis, N2 sorption and scanning electronic microscopy, and their performance was tested in adsorptive denitrogenation for model fuel containing pyridine or quinoline. Although Ti-HMS/KIL-2 composites were constructed following the different pathway of self-assembly, most of them obtained coexisting properties and structures of Ti-HMS and Ti-KIL-2, as well as the intact framework Ti in tetrahedral coordination. A key finding is that the mesopores size of Ti-KIL-2 component in the composite can be regulated via the introduction of Ti-HMS precursor or organic template dodecylamine. Especially, the composites of dual-template method presented hierarchical mesopores with obvious bimodal distribution. In addition to constructing the hierarchical structure, introduction of Ti-HMS into Ti-KIL-2 matrix improved the adsorptive denitrogenation performance, which was influenced by the synthetic strategy of Ti-HMS/KIL-2. The target adsorbates achieved the best match with the adjustable pores of Ti-HMS/KIL-2. Therefore, (0.6D)Ti-HMS/KIL-2 and (0.5T)Ti-HMS/KIL-2 as the optimized adsorbents obtained remarkable adsorption efficiency respectively for pyridine and quinoline. Essence of the adsorptive denitrogenation process was revealed via the adsorption isotherms and the adsorption thermodynamics. Finally, Ti-HMS/KIL-2 composites achieved the improvement in hydrothermal stability and recyclability during adsorption of pyridine and quinoline, and exhibited the potential of industrial application.

Graphical abstractTwo methods for synthesis of bimodal mesoporous Ti-HMS/KIL-2 composites as adsorbents of nitrogen-containing compounds in fuel.Download high-res image (72KB)Download full-size image