Remarkable metal–organic framework composites for adsorptive removal of nitrogenous compounds from fuel

A metal–organic framework (MOF) composite ZIF-67(x)@H₂N-MIL-125 [Z67(x)@M125] was designed and synthesized for the first time. The synthesis was optimized by the varying composition of the Z67 content (e.g., weight percent of Z67 was varied from 0 to 50% of the total amount of the main precursors for the M125) and reaction time (1–16 h). Adsorptive removal of organo-nitrogen compounds (ONCs) from model fuel was done after the detail characterization of the Z67(0–10)@M125 (composite with 0–10% of Z67). The Z67(5.0)@M125 (a MOF composite with 5% of Z67) was observed as the best material among the studied adsorbents for the tested adsorbates (ONCs). Moreover, the adsorption efficiency of the ONCs was further improved when Z67(5.0)@M125 was protonated. Importantly, the protonated Z67(5.0)@M125 showed the highest adsorption capacity, especially for IND, compared with any reported adsorbent so far, based on MOFs or activated carbon. Based on the adsorption results and the properties of the adsorbent/adsorbates, plausible adsorption mechanisms could be suggested. The developed Z67(5.0)@M125 can be readily recycled with negligible loss of performance.