New hierarchical nanosheet zeolite catalysts could improve efficiences in fuel, chemical and pharmaceutical production
|The research team used a unique process to encourage growth of ultra-thin zeolite nanosheets at 90-degree angles, similar to building a house of cards. Credit: U of Minn. Click to enlarge.|
An international team led by University of Minnesota chemical engineering and materials science professor Michael Tsapatsis reports in the journal Science on a prototype of a new catalyst made of orthogonally connected microporous zeolite nanosheets (earlier post). The new development could lead to major efficiencies and cost-savings in catalyst-dependent production of gasoline, plastics, biofuels, pharmaceuticals, and other chemicals.
The “house-of-cards” arrangement of the nanosheets creates a permanent network of 2- to 7-nanometer mesopores, which, along with the high external surface area and reduced micropore diffusion length, account for the higher reaction rates for bulky molecules relative to those of other mesoporous and conventional MFI zeolites. The structure improves efficiencies by giving molecules fast access to the catalysts where the chemical reactions occur.
The nanosheets are 2 nanometers thick and contain a network of 0.5-nanometer micropores.
It’s faster and more efficient to use freeways to get where we want to go and exit to do our business compared to driving the side streets the entire way. The catalysts used today are more like all side streets. Molecules move slowly and get stuck. The efficiencies of these new catalysts could lower the costs of gasoline and other products for all of us.—Michael Tsapatsis
Although the nanosheets make the catalyst faster, more selective and more stable, the catalyst can be made at the same cost (or possibly cheaper) than traditional catalysts.
This new discovery builds upon previous discoveries at the University of Minnesota of ultra-thin zeolite nanosheets used as specialized molecular sieves for production of both renewable and fossil-based fuels and chemicals.
These discoveries, licensed by the new Minnesota start-up company Argilex Technologies, are key components of the company’s materials-based platform. Co-founded by Gonzalez and Tsapatsis, Argilex launched in early March 2012. The development of the new catalyst is complete, and the material is ready for customer testing.
This breakthrough can have a major impact on both the conversion of natural gas to higher value chemicals and fuels, and on bio- and petroleum refiners. Using catalysts made by this novel approach, refiners will be able to obtain a higher yield of desirable products such as gasoline, diesel, ethylene and propylene. At Argilex, we envision this catalyst technology platform to become a key contributor to efficient use of natural resources and improved economics of the world's largest industries.—Cesar Gonzalez, CEO of Argilex Technologies
In addition to the University of Minnesota, the researchers on the team are from private and academic institutions in Tokyo, Abu Dhabi, S. Korea and Sweden.
Xueyi Zhang, Dongxia Liu, Dandan Xu, Shunsuke Asahina, Katie A. Cychosz, Kumar Varoon Agrawal, Yasser Al Wahedi, Aditya Bhan, Saleh Al Hashimi, Osamu Terasaki, Matthias Thommes, and Michael Tsapatsis (2012) Synthesis of Self-Pillared Zeolite Nanosheets by Repetitive Branching. Science 336 (6089), 1684-1687. doi: 10.1126/science.1221111