Effective mesoporous silica-ZIF-8 nano-adsorbents for adsorptive desulfurization of gas stream

Abstract

Abstract New hybrids (MCM-41@Z-8, SBA-15@ZIF-8 and UVM-7@ZIf-8) were synthesized using mesopore templates for the growth of ZIF-8 nanoparticles and characterized by FT-IR, XRD, FE-SEM and BET analyses. The sulfur-removal performance of prepared hybrids were then investigated by changing temperature from 30 to 50 °C under the operational conditions of 34,000 h−1 space velocity and the feed concentrations of 45,000 and 1300 ppm for H2S and CH3CH2SH from gas stream, respectively. The optimum breakthrough capacities for MCM-41@ZIF-8, SBA-15@ZIF-8 and UVM-7@ZIF-8 by setting the temperature at 30 °C were reported as 4.92, 5.21 and 6.12 g S/g sorbent for the removal of hydrogen sulfide and 1.32, 1.30 and 1.47 g S/g sorbent for the removal of ethyl mercaptan, respectively. UVM-7@ZIF-8 was shown as the best nano-adsorbent due to the dual-pore size distribution (pore size: 1.22 and 47.67 nm), and higher BET surface area of about 937.23 m2/g in contrast to MCM-41@ZIF-8 (849.99 m2/g), and SBA-15@ZIF-8 (770.79 m2/g). In addition, the introduction of metal active sites of Zn is associated with the improved properties of synthesized nano-adsorbents compared to the starting mesopore templates. The uptake capability of the synthesized nano-adsorbents have only reduced to about 6–9% and 9–12% after 4 cycles of hydrogen sulfide and ethyl mercaptan adsorption, respectively.