Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers

Abstract

As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr6O4(OH)4(bptc)3 adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr6O4(OH)8(H2O)4(abtc)2, is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.

Tailor‐Made Microporous Metal–Organic Frameworks for the Full Separation of Propane from Propylene Through Selective Size Exclusion

“…We recently reported topology‐guided construction of Zr‐MOFs built on tetratopic carboxylate linkers and their uses for the separation of C6 alkane isomers . As Zr 6 O 8 building block is commonly adopted in Zr‐MOFs, their structural topology, depending on the connectivity of the Zr6 cluster and the geometry of the organic linker, is generally predictable or designable by making use of reticular chemistry.…”

Splitting Mono- and Dibranched Alkane Isomers by a Robust Aluminum-Based Metal–Organic Framework Material with Optimal Pore Dimensions

“…The dynamic adsorption capacity 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 3 is notably higher than that of zeolite 5A under identical conditions. 13 Real-time RON detection indicates that the initial eluent has a RON of more than 90, well meeting the requirement for gasoline blending components. The notably longer retention of nHEX compared to 3MP could be a result of combined effect of thermodynamics and kinetics, agreeing with the results from single-component adsorption isotherms.…”

“…5 MOFs have demonstrated exceptional performance for the separation of hydrocarbons, such as paraffins/olefins and alkane isomers. [6][7][8][9][10][11][12][13][14] Several MOF materials, including Y-fum, 11 Fe2(BDP)3, 12 Zr-bptc, Zr-abtc, 13 Ca-tcpb 14 , have shown similar or even better performance for the separation of alkane isomers compared to zeolite 5A, with respect to adsorption capacity or selectivity. However, to date, none of the reported materials have reached optimum performance.…”

A Dual Threat: Redox‐Activity and Electronic Structures of Well‐Defined Donor–Acceptor Fulleretic Covalent‐Organic Materials

“…Merging the properties of three‐dimensional buckyballs (or buckybowls) and covalent‐organic frameworks (COFs) provides access to a novel class of materials combining ultrafast energy/electron transport characteristic of three‐dimensional (3D) fulleretic linkers with high modularity, crystallinity, and surface area, which are intrinsic properties of COFs . The precise donor–acceptor alignment achieved in the materials is imposed by the rigid COF scaffold and is crucial for efficient energy or charge transfer as it can influence the distance of exciton diffusion, π–π stacking, or Förster radius, and as a result, can enhance device performance …”