Functionalization effects on HKUST-1 and HKUST-1/graphene oxide hybrid adsorbents for hydrogen sulfide removal.

HKUST-1, a Cu-based metalorganic framework (MOF), was synthesized solvothermally, functionalized with polyethyleneimine (PEI), and hybridized with graphene oxide (GO) and functionalized GO for HS removal. MOF synthesis approach, molecular weight of amines, and the content of GO in the hybrid adsorbents were systematically varied. The adsorbent materials were characterized by XRD, FTIR, SEM, elemental analysis, liquid N adsorption-desorption, water vapor and oxygen sorption, and subsequently tested for HS adsorption in a breakthrough column. The MOF in the composite adsorbents consisting of in-situ grown HKUST-1 on GO that was pre-functionalized with low molecular weight PEI exhibited the highest HS adsorption uptake at ambient conditions (0.9 mmol S g MOF) in comparison to 0.5 mmol S g MOF for the parent HKUST-1, thus showing an 80 % increase in uptake, while this material also exhibited significantly enhanced sorption kinetics. HS adsorption at higher temperature (150 °C) was also performed, and at this temperature a HKUST/GO hybrid adsorbent resulted in the highest MOF capacity, i.e. 2.1 mmol S g MOF, which is 27 % higher than that of the parent MOF at the same conditions. Formation of hybrid adsorbents with GO coupled to tunable functionalization of both GO support and the MOF crystallites can contribute in optimizing HS capture performance of MOFs.