Cu-TDPAT, an <i>rht</i>-Type Dual-Functional Metal–Organic Framework Offering Significant Potential for Use in H₂ and Natural Gas Purification Processes Operating at High Pressures

The separations of CO₂/CO/CH₄/H₂, CO₂/H₂, CH₄/H₂, and CO₂/CH₄ mixtures at pressures ranging to 7 MPa are important in a variety of contexts, including H₂ production, natural gas purification, and fuel-gas processing. The primary objective of this study is to demonstrate the selective adsorption potential of an <i>rht</i>-type metal–organic framework [Cu₃(TDPAT)­(H₂O)₃]·10H₂O·5DMA (Cu-TDPAT), possessing a high density of both open metal sites and Lewis basic sites. Experimental high pressure pure component isotherm data for CO₂, CO, CH₄, and H₂ are combined with the Ideal Adsorbed Solution Theory (IAST) for estimation of mixture adsorption equilibrium. The separation performance of Cu-TDPAT is compared with four other microporous materials, specifically chosen in order to span a wide range of physicochemical characteristics: MgMOF-74, MIL-101, LTA-5A, and NaX. For all mixtures investigated, the capacity of Cu-TDPAT to produce the desired product, H₂ or CH₄, satisfying stringent purity requirements, in a fixed bed operating at pressures exceeding about 4 MPa, is either comparable to, or exceeds, that of other materials

Introduction of π‑Complexation into Porous Aromatic Framework for Highly Selective Adsorption of Ethylene over Ethane

In this work, we demonstrate for the first time the introduction of π-complexation into a porous aromatic framework (PAF), affording significant increase in ethylene uptake capacity, as illustrated in the context of Ag­(I) ion functionalized PAF-1, PAF-1-SO₃Ag. IAST calculations using single-component-isotherm data and an equimolar ethylene/ethane ratio at 296 K reveal that PAF-1-SO₃Ag shows exceptionally high ethylene/ethane adsorption selectivity (<i>S</i>_ads: 27 to 125), far surpassing benchmark zeolite and any other MOF reported in literature. The formation of π-complexation between ethylene molecules and Ag­(I) ions in PAF-1-SO₃Ag has been evidenced by the high isosteric heats of adsorption of C₂H₄ and also proved by in situ IR spectroscopy studies. Transient breakthrough experiments, supported by simulations, indicate the feasibility of PAF-1-SO₃Ag for producing 99.95%+ pure C₂H₄ in a Pressure Swing Adsorption operation. Our work herein thus suggests a new perspective to functionalizing PAFs and other types of advanced porous materials for highly selective adsorption of ethylene over ethane