The development of intracrystalline mesoporosity within zeolites has been a long-standing goal in catalysis as it greatly contributes to alleviating the diffusion limitations of these widely used microporous materials. During my presentation, I will discuss the main techniques that have been developed during the last years to produce zeolites with controlled mesoarchitectures comparing the different methods, their advantages, and limitations. Among the different techniques used to characterize the composition, porosity, and structure of these materials, I will present unprecedented insights on the formation of intracrystalline mesoporosity in zeolites obtained by in situ synchrotron X-ray diffraction and Liquid Cell Transmission Electron Microscopy (Liq-TEM). By combining experimental results and theoretical calculations, the presence of intracrystalline mesoporosity was recently confirmed. Moreover, through the observation of individual zeolite crystals by Liq-TEM, we are able to provide the first time-resolved visualization of the formation of mesoporosity in zeolites. The presence of this mesoporosity was further evidenced through ex situ gas adsorption, which also confirmed the preservation of most of the microporosity of the zeolites. All these new insights, obtained by combining a number of time-resolved techniques, are an example of the enormous potential of current in situ characterization methods for the rational design of hierarchical zeolites with superior properties and optimal catalytic performance as it has been proved at lab, pilot plant, and industrial scale. These nanostructured catalysts, which are being produced at multi-ton scale by G.W. Grace, allow refiners to increase refining margins by as much as $0.90 per barrel and refinery profitability by $50 million per year. It is estimated that in a medium-size refinery the use of our technology allows for an annual reduction of 100,000 tons of CO2. The commercialization of hierarchical zeolites through the MIT spin-off Rive Technology as superior refining catalysts is an example of academic entrepreneurship, which is expected to foster the development of new hierarchical zeolites and their use in both existing processes and new opportunities. Finally, I cover other applications of hierarchical zeolites in catalysis, including biomass valorization and fine chemistry, ending with a personal view of the new directions, and opportunities in this field.

Discovery and commercialization of nanostructured zeolites: An example of chemistry entrepreneurship that creates value and reduces CO2 emissions

ACS Fall 2021

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