THE PROBLEM

Conventional separation technologies to separate valuable commodities are energy-intensive, consuming 15% of the worldwide energy.

 THE SOLUTION

We report the rational design and construction of a highly efficient, mixed-matrix metal-organic framework membrane based on three interlocked criteria: 

1. A fluorinated metal-organic framework, AIFFVE-1-Ni, as a molecular sieve adsorbent that selectively enhances hydrogen sulfide and carbon dioxide diffusion while excluding methane. 
2. Tailoring crystal morphology into nanosheets with maximally exposed (001) facets;
3. In-plane alignment of (001) nanosheets in polymer matrix and attainment of [001]-oriented membrane.

RESULT 

The membrane demonstrates exceptionally high hydrogen sulfide and carbon dioxide separation from natural gas under practical working conditions.

FURTHER USEABILITY

The separation performances of oriented membranes were further tested for other gas pairs, including H2/N2, H2/CH4 and H2/C3H8 and subsequently compared with the literature. The resultant membranes exhibit excellent selectivity and permeability enhancement for these gas pairs far beyond the upper bounds for polymeric membranes.

In fact, this centimeter-scale flexible [001]-oriented membrane can be regarded as a single piece of a flexible crystal in which thousands of nanosheets are uniformly aligned in a predefined crystallographic direction and the gaps between aligned nanosheets are filled with polymer. The results confirm the potential of tailoring MOF crystal morphology into oriented nanosheets, allowing the desired orientation of the 1D channels parallel to the gas diffusion direction and proffering opportunities to maximize the performance of the oriented membrane, as demonstrated here for various gas separations.

Read article: https://www.science.org/doi/10.1126/science.abe0192

Read KAUST Discovery story:

https://discovery.kaust.edu.sa/en/article/1251/membrane-offers-an-efficient-way-to-purify-gas-mixtures