(6bj) Controlled Catalytic Capability through Tailored Nanoporous Materials: For Selective and Sustainable Chemical Processes

My Ph.D. work with Prof. Wei Fan in the department of Chemical Engineering at University of Massachusetts, Amherst, focused on the synthesis of nanoporous catalytic materials such as zeolites, metal oxides and porous carbon for biomass upgrading processes. In particular, hierarchical Lewis acid zeolites were developed by a seeded growth within mesoporous carbon, and showed >3 times higher catalytic activities for sugar isomerization reactions, compared to conventional Lewis acid zeolites. In addition, the Lewis acid zeolite supported Pt nanoparticles could effectively catalyze glycerol oxidation to form lactic acid with 72% yield through multi-step pathways, whereas no lactic acid was produced over typical metal oxide-supported Pt catalysts. Furthermore, phosphorous-containing zeolite and silica materials achieved 97% yield of p-xylene via a renewable route from biomass. The key to this success was to introduce weak Brønsted acid sites into the catalytic materials, which stems from phosphoric acid on the solid. In contrast, conventional heterogeneous catalysts with Lewis or Brønsted acid sites gave p-xylene at a maximum yield of ~70%, due to catalyst deactivation.

My current postdoctoral work with Prof. Bingjun Xu in the department of Chemical & Biomolecular Engineering at University of Delaware is to develop multicomponent catalysts which mediate a tandem reaction in one-pot. I successfully synthesized a family of zeolite-encapsulated metal catalysts via a novel synthetic approach. The encapsulated catalyst exhibited outstanding catalytic performances, compared to supported metal catalysts, in tandem Aldol condensation and hydrogenation of furfural with acetone. I am also exploring new catalytic system of tandem catalysis mediated by zeolite-encapsulated metal catalysts.

Before starting Ph.D., I had worked for several years in Research and Development (R&D) department of Polymer Industry. During this period, my work aimed at studying and designing polymer properties on a commercial scale via various polymer characterization and processing techniques. This industry experience broadened my perspective towards how polymeric materials should be developed for their use in the real world.

The expertise and experience in the synthesis and characterization of inorganic and organic materials and the heterogeneous catalysis prepared me for my independent research career. I aim to establish a research program on the rational design of advanced nanoporous materials (such as zeolites, metal-organic frameworks (MOFs), porous polymers, etc.) for catalytic applications. My research will be motivated by grand challenges in energy and environmental issues, in particular, shale gas conversion to chemicals, sustainable production of fuels and chemicals, emission control catalysis, CO₂ conversion, and catalysis for waste water treatment.

Selected publications: (22 Total, 632 Citations, h-index 16)

1. H. J. Cho, L. Ren, V. Vattipalli, Y.-H. Yeo, N. Gould, B. Xu, R. J. Gorte, R. Lobo, P. J. Dauenhauer, M. Tsapatsis and W. Fan, “Renewable p-xylene from 2,5-dimethylfuran and ethylene using phosphorus-containing zeolite catalysts”, ChemCatChem, 9, 2017, 398-402

• One of the top 14 most-accessed articles on ChemCatChem, October 2016
• Released in the Newspapers Business Standard (http://business-standard.com), Higher Education Tribune (http://www.highereducationtribune.com) and Biomass Magazine (http://biomassmagazine.com)
• Patent (No. PCT/US2017/054558), entitled “Phosphorus-containing solid catalysts and reactions catalyzed thereby, including synthesis of p-xylene”

2. K. Rieger*, H. J. Cho*, H. Yeung, W. Fan and J. Schiffman, “Antimicrobial activity of silver ions released from zeolites immobilized on cellulose nanofiber mats”, ACS Appl. Mater. & Interfaces, 8 (5), 2016, 3032-3040 (* Equally contributed)
3. C.-C. Chang, H. J. Cho, J. Yu, R. J. Gorte, J. Gulbinski, P. Dauenhauer and W. Fan, “Lewis acid zeolites for tandem Diels-Alder cycloaddition and dehydration of biomass-derived dimethylfuran and ethylene to renewable p-xylene”, Green Chem., 18, 2016, 1368-1376
4. P. Dornath, H. J. Cho, A. Paulsen, P. Dauenhauer and W. Fan, “Efficient mechano-catalytic depolymerization of crystalline cellulose by formation of branched glucan chains”, Green Chem., 17 (2), 2015, 769-775

• Featured on Inside Front Cover

5. H. J. Cho, C.-C. Chang and W. Fan, “Base free, one-pot synthesis of lactic acid from glycerol using a bifunctional Pt/Sn-MFI catalyst”, Green Chem., 16 (7), 2014, 3428-3433

• Featured on Front Cover
• One of the top 15 most-read articles on Green Chemistry from May to July of 2014

6. H. J. Cho, P. Dornath and W. Fan, “Synthesis of hierarchical Sn-MFI as Lewis acid catalysts for isomerization of cellulosic sugars”, ACS Catal., 4 (6), 2014, 2029-2037
7. H. J. Cho, H. S. Jang, S. H. Lim, E. A. Cho, T.-H. Lim, I.-H. Oh, H.-J Kim and J. H. Jang, “Development of a novel decal transfer process for fabrication of high-performance and reliable membrane electrode assemblies for PEMFCs”, Int.J.Hydrogen Energy, 36, 2011, 12465-12473

Teaching Interests:

I enjoy conveying my knowledge to others as well as exploring new technologies with them. I am comfortable in teaching many of the core chemical engineering courses (Chemical kinetics, Thermodynamics, Mass and Energy balances, and Heat & Mass transfer). I would also be interested in teaching more specialized courses in i) heterogeneous catalysis, ii) nanoporous materials chemistry and engineering, and ii) characterization of nanostructured materials as elective courses at a graduate level.