Hong Je Cho, a doctoral student on the research team of Professor Wei Fan (Fan Porous Materials Research Group) of the Chemical Engineering Department, won third place in the oral presentation award competition in the Fifth Annual Graduate Student Award Symposium at the American Chemical Society (ACS) fall meeting in Boston. This year seven finalists, chosen from more than 100 applicants pursuing Ph.D. degrees from research institutions nationwide, described their works at the symposium. Cho presented his work on the development of Lewis acid zeolite catalysts for biomass conversion.
The title of the paper was “Nanoporous Sn-MFI Catalyst with Lewis Acidity for Biomass Conversion: Synthesis, Catalysis and Chemistry,” by Cho and Fan.
The research described in the paper demonstrated superior catalytic performance for the isomerization of certain cellulosic sugars, offering at least 14 times higher activities than conventional reactions of the same kind. In addition, Cho and Fan said that, to the best of their knowledge, their research led to the highest yield of lactic acid achieved using heterogeneous catalysts under base-free environments.
As Fan explained, “The research of our group focuses on the rational synthesis of nanoporous materials for biorefinery and drug delivery. The pore structure and size, surface properties, and active sites are tailored based on the comprehensive understanding of their crystallization mechanism.”
In the context of that research, the paper presented by Cho described the particular background of his research: “Increasing demand for energy and commodity chemicals has led to accelerated research efforts in the conversion of renewable resource into chemicals and fuels for a sustainable economy. The processing of lignocellulosic biomass, an inexpensive, inedible, and abundant source of carbon, offers the promise of sustainable chemicals and carbon-neutral liquid transportation fuels.”
Some Lewis acid catalysts called zeolites play a pivotal role for selectively activating functional groups of the organic molecules involved in biomass conversion.
As the abstract of Cho’s paper explained his specific research, catalytic “zeolites are crystalline microporous materials with distinct pore dimensions, connectivity, and framework compositions, which are widely used in petrochemical and biomass processing. However, the catalytic performance of zeolites is frequently hindered by the slow molecular diffusion in the microporous networks, in particular when bulky molecules are involved. A proven strategy to overcome the diffusion limitation is to create secondary mesopores into zeolites, leading to the formation of hierarchical porous structures.”
In this work, hierarchical stannosilicate molecular sieves with ordered mesoporosity and MFI topology (three dimensionally ordered mesoporous imprinted Sn-MFI) have been successfully synthesized within the confined space of three-dimensionally ordered mesoporous carbon via a seeded growth approach.
As Cho wrote, “The hierarchical Sn-MFI exhibits superior catalytic performance for the isomerization of cellulosic sugars, in particular, offering at least 14 times higher activities than conventional bulky sized Sn-MFI for C5 and C6 sugar reactions. In addition, bifunctional Lewis acid Sn-MFI supported Pt nanocrystals led to exceptional selectivities of lactic acid from glycerol oxidation under base-free conditions. Specifically, 80.5% selectivity of lactic acid was achieved at 89.8% conversion of glycerol.”
Cho added that “To the best of our knowledge, it is the highest yield of lactic acid achieved using heterogeneous catalysts under base-free environments. This catalytic system provides a new cascade reaction pathway to combine a metal catalyst and a Lewis acid catalyst, which can overcome the thermodynamic and kinetic barrier of multistep reactions involved in biomass conversion.”
In addition, Cho’s work on this project has been published in ACS Catalysis and in Green Chemistry. The work about production of lactic acid with a high yield was highlighted on the front cover of Green Chemistry.
The two citations are:
- Cho, H. J.; Chang, C.-C.; Fan, W., Base free, one-pot synthesis of lactic acid from glycerol using a bifunctional Pt/Sn-MFI catalyst, Green Chemistry. 2014, 16, 3428-3433
- Cho, H. J.; Dornath, P.; Fan, W., Synthesis of Hierarchical Sn-MFI as Lewis Acid Catalysts for Isomerization of Cellulosic Sugars, ACS Catalysis. 2014, 4, 2029-2037
This gathering of the American Chemical Society, held between August 16 and 20 in Boston, represented the 250th Meeting and was entitled “Innovation from Discovery to Application”.
As the call for papers at the Boston meeting said, "The Industrial and Engineering Chemistry Division requests papers for its Fifth Annual Graduate Student Award Symposium. This event allows outstanding graduate students in the chemical sciences to disseminate their research to the global professional community." (October 2015)