Perfluoroalkyl acids of different chain lengths, including trifluoroacetic acid, heptafluorobutyric acid, and nonafluoropentanoic acid, were used as second ligands to replace the formic acid on the Zr₆ clusters in MOF-808. This led to the formation of a series of MOF-808-R materials (R=F₃, F₇, F₉, corresponding to trifluoroacetic acid, heptafluorobutyric acid, and nonafluoropentanoic acid) with multiple ligands, and we investigated the impact of the second ligand modification on pore size and pore environment. The loading amount of the second ligand was determined using NMR and other methods. We conducted adsorption tests for acetylene and carbon dioxide at different temperatures on both MOF-808 and MOF-808-R to explore the effects of the ligand diversification on acetylene separation performance. It was found that MOF-808-F₇ exhibited the best performance in acetylene-carbon dioxide separation.