A new 3D extra-large pore zeolite has been created, which opens up a way to decontaminate water and gas
Researchers from theInstituto de Nanociencia y Materiales de Aragón (INMA), a joint institute of CSIC and the University of Zaragoza, are part of the international team of researchers that has created the most porous stable zeolite known to date, a new pure silica zeolite called ZEO-3. This zeolite was formed by an unprecedented topotactic condensation of a 1D silicate chain to a 3D zeolite. The process is topotactic because the chain structure is not altered. It can be applied to remove and recover volatile organic compounds from a gas stream that may even contain water. The discovery, to which scientists from the Instituto de Ciencias de Materiales de Madrid (ICMM-CSIC) and the Instituto de Nanociencia y Materiales de Aragón, INMA, (CSIC-UNIZAR) have contributed, is published in the journal Science.
Zeolites are microporous silicates that find a wide variety of applications as catalysts, adsorbents and cation exchangers. Currently, stable silica-based zeolites with higher porosity are in demand to allow adsorption and processing of large molecules, “but they defy our synthetic capabilities,” explains Miguel Camblor, ICMM-CSIC researcher and one of the lead authors of the paper.
As the pores of zeolites are the size of small molecules, there is a limitation in the size of the molecules that can be processed. “That is why zeolites with larger pores have always been sought after, especially those with pores in three dimensions, because when you have a pore in only one direction, even if it is large, it is easy to get blocked. However, if you have them in all dimensions, it is difficult,” says Camblor.
After more than 80 years of international research in this field, the team of scientists has created the most porous stable zeolite known so far. “Until now, zeolites with extra-large pores were not stable, as they were made of germanium instead of silicon,” says the ICMM-CSIC researcher. Previous stable zeolites could reach up to 7 angstroms (1 angstrom is one hundred millionth of a centimetre). Last year, this team of researchers published another paper in Science on a new zeolite with aluminium and large pores (ZEO-1). Now, the new zeolite has a pure silica composition. “In both zeolites, ZEO-1 and ZEO-3, there are pores that reach more than 10 angstroms,” says Camblor.
The peculiarities of ZEO-3
The new zeolite has two peculiarities: extra-large pores in all three dimensions and that it is formed by calcination of a one-dimensional chain silicate in a topotactic condensation (meaning that it was made without changes in this chain).
“This has never been seen before,” says Camblor. “Two-dimensional to three-dimensional topotactic condensations were known, that is, a material that was a sheet and that, by a similar mechanism, condensed to give a zeolite, but not from one-dimensional to three-dimensional,” he adds.
After the creation of this zeolite, the team, which also includes scientists from Sweden, China and the United States (US), began to experiment with its properties: “As it is a material that is pure silica, it has no catalytic capacity, but it has the capacity to absorb very large organic compounds,” says Camblor.
“This zeolite can be applied to remove and recover volatile organic compounds from a gas stream that may even contain water,” he explains. “At a site where harmful volatile organic materials are being produced, you can decontaminate and not only remove it but recover the contaminant,” Camblor illustrates. With further research, this zeolite could also be useful in catalysis and drug delivery.
Jian Li, Zihao Rei Gao, Qing-Fang Lin, Chenxu Liu, Fangxin Gao, Cong Lin, Siyao Zhang, Hua Deng, Álvaro Mayoral, Wei Fan, Song Luo, Xiaobo Chen, Hong He, Miguel A. Camblor, Fei-Jian Chen and Jihong Yu.
“A 3D Extra-Large Pore Zeolite Enabled by 1D-to-3D Topotactic Condensation of a Chain Silicate”
Science, 19 Jan. 2023, Vol 379, Issue 6629, pp. 283-287