Rational Construction of Ultrahigh Thermal Stable MOF for Efficient Separation of MTO Products and Natural Gas

Considering the important application foundation of propylene (C 3 H 6 ) and ethylene (C 2 H 4 ) production, as well as methane (CH 4 ), in petrochemical industries, this report comprehensively investigated an innovative MOF material (Zn-BPZ-SA) that was synthesized by 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (H 2 BPZ) and squaric acid (H 2 SA) for separating methanol-to-olefins (MTO) products (C 3 H 6 /C 2 H 4 mixtures) and natural gas (C 3 H 8 /C 2 H 6 /CH 4 mixtures). Zn-BPZ-SA with great resistance toward water and exceptional thermal stability (520 °C), can preferentially adsorb C 3 H 8 and C 3 H 6 rather than C 2 H 6 and C 2 H 4, and in particular, reveals high C 3 H 6 and C 3 H 8 uptakes of 46.6 and 48.0 cm 3 g –1 under the crucial low pressure (10 kPa, 298 K). The experimental and simulated transient breakthroughs for C 3 H 6 /C 2 H 4 binary mixtures and C 3 H 8 /C 2 H 6 /CH 4 ternary mixtures demonstrated that the MOF can separate these mixtures with long breakthrough time differences, yielding high-purity (>99.95%) products with high productivities: C 2 H 4 (21.9–142.8 L kg –1 ) and CH 4 (34.9–73.0 L kg –1 ). The excellent separation abilities can be attributed to the rich accessbile O/N and methyl binding sites scattered at the pore surfaces in framework.