Topologically guided tuning of Zr-MOF pore structures for highly selective separation of C6 alkane isomers.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29717138.
- Also identified by DOI 10.1038/s41467-018-04152-5 and PMC identifier 5931593.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
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. Zr<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub>(bptc)<sub>3</sub> 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, Zr<sub>6</sub>O<sub>4</sub>(OH)<sub>8</sub>(H<sub>2</sub>O)<sub>4</sub>(abtc)<sub>2</sub>, 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.