Effect of hierarchical porous MOF-199 regulated by PVP on their ambient desulfurization performance

Hierarchical porous MOF-199 with small crystal sizes was synthesized via PVP (Polyvinylpyrrolidone) regulation in an aqueous system, in which PVP acted as nucleating, coordination and template agent. The ambient desulfurization performance of the obtained MOF-199 regulated with different PVP amounts toward CH3SCH3 and H2S and their structure-performance relationship were systematically studied. It is found that CH3SCH3 was first chemisorbed on the surface of the adsorbent in a monolayer by weak coordination and then physisorbed in multilayers. This whole process was reversible and the structure of MOF kept stable. The hierarchical pores plus the small crystal size of MOF-199-P1, especially to the latter, endowed the uptake for CH3SCH3 reaching 88.1 mg S/g, 42% higher than that of pristine MOF-199. However, the adsorption of H2S by MOF-199 is chemical and the collapse of the MOF structure was observed. The hierarchical porous structure helped H2S access as many active sites as possible before the blockage of pores caused by the structural damage. As a result, MOF-199-P2 achieved the optimum breakthrough capacity of 74.3 mg S/g towards H2S, 34 % higher than the bare MOF-199. This study provides new strategies and insights for the adsorption process between sulfide and adsorbents in different reaction modes.