Biological Materials

Research Interests:

Recent advances in natural gas/shale gas technology, especially as practiced in the United States, has significantly improved the economics for producing ethylene and has revolutionized manufacturing approaches to basic chemicals, polymers and materials. Ethane is second to methane as the major hydrocarbon component of natural gas/shale gas, serving as the precursor to ethylene. Ethylene is one of the most important building blocks in the chemical industry and provides the starting point for many essential consumer products such as performance polymers, plastics, and functional chemical intermediates. The greatest challenge for any natural gas/shale gas application is direct production of high value chemicals with limited separation requirements.

The selective oxidative dehydrogenation (ODH) process provides an alternative to ethylene production via naphtha or ethane steam cracking. Steam cracking is the most energy-intensive process in the chemical industry, using approximately 8% of all energy consumed by the chemical industry. The exothermic ODH reaction can significantly reduce the energy consumption compared to steam cracking with a much lower reaction temperature (< 400°C for ODH and > 800°C for steam cracking). ODH of ethane to ethylene also provides higher selectivity to ethylene compared to steam cracking and is not equilibrium-limited.

My previous study has shown that with novel composition and synthesis method, mixed metal oxide catalyst can offer high selectivity and conversion for ethane ODH reaction. The orthorhombic M1 catalyst (MoVTeNbO_x) with optimized composition offers > 90% selectivity with > 70% conversion. However, it is still difficult for the ODH process to compete with steam cracking of ethane due to all currently existing steam cracking plants and the economy of scale for steam crackers, which are typically 2 – 4 Blbs/yr in capacity. Price differences of natural gas and ethylene also vary with location and season to make the ODH process less competitive. Further, ODH of ethane from natural/shale gas often requires separation of methane, unreacted O₂, and other hydrocarbon impurities before the ethylene purity is high enough for downstream applications such as polyethylene synthesis.

My future work and research aims to lead the development of novel catalysts by unique composition and structure for catalytic conversion of light hydrocarbons to high value chemicals specially for ethylene oxide and ethylene glycol from natural/shale gas. Novel catalysts synthesis and development will be combined with a rational process for direct production of ethylene oxide (EO) from natural/shale gas using the combination of oxidative dehydrogenation (ODH) of ethane to ethylene and epoxidation of ethylene to EO. Ethylene oxide-derived products are especially relevant to feed the ever-growing market for EO which is at ~4%/year; approximately 10 - 15 Blbs/year of new EO capacity are scheduled to come on-line by 2020 on the Texas-Louisiana gulf coast.

The core components of this study are rational catalysts with high selectivity and long lifetime for both ODH and EO processes, as well as two successive reactor systems for direct production of high value chemicals (ethylene oxide and ethylene glycol) from natural gas. With the price difference between EO/EG and natural gas-derived ethylene, there is a significant profit potential for direct production of EO from natural gas/shale gas, particularly if separations and gas recycle can be avoided. This will make the new process more competitive compared to the existing cracking plants. Another important approach is to limit separation requirements with the addition of the EO process after ODH. Using the full composition of the gas stream from the ODH reactor provides a great process advantage, since in principle no separation should be required between the ODH and EO reactors.

The success of this selective oxidation research can fundamentally change the utilization of remote natural gas fields in the United States, not only with respect to EO as a desired chemical product, but possibly for other products as well, such as hydration of ethylene to fuel grade ethanol. With limited separation requirements, direct production of high value chemicals and use of modular, portable reactors, this potentially low cost technology can be used for most natural gas fields in the United States. The ultimate result of the research will be significant, impacting the value chain and U.S. competitiveness for natural gas-derived feedstocks. Additionally, the scientific knowledge acquired will advance other manufacturing technologies, such as selective oxidation of methane and other hydrocarbons.

Funded projects:

(Total amount of projects as PI and Co-PI is more than $750,000. Specific amount for Dr. Diao is more than $290,000)

Principal Investigator:

1. U.S. National Science Foundation (NSF), Industry–University Cooperative Research Centers Program (IUCRC) of Center for Rational Catalyst Synthesis (CeRCaS), “Boron nitride (BN) supported metal and metal oxide catalysts for selective oxidation reactions”, NSF 1464630-PJ15, 06/2018-12/2019
2. U.S. Department of Energy (DOE), Laboratory Directed Research and Development (LDRD), “Catalysts development for water splitting reactions using solid oxide electrolysis cells (SOECs)”, DE-AC07-051D14517-216845, 03/2019-09/2019

Co-Principal Investigator:

1. U.S. Department of Energy (DOE), Laboratory Directed Research and Development (LDRD), “Kinetic-based Scale-Up Science for an Energy Efficient Route to Ethylene”, 16P6-002FP, 06/2016-09/2017
2. University of South Carolina, Advanced Support for Innovative Research Excellence (ASPIRE) III, “In situ high temperature and variable gas environment X-ray Diffractometer for study of effects of temperature and gas environment on stability of catalysts and other novel materials”, 15510-18-48251, 07/2018-09/2019
3. U.S. National Science Foundation (NSF), Industry–University Cooperative Research Centers Program (IUCRC) of Center for Rational Catalyst Synthesis, “Computational and experimental analysis of Ag catalysts with GNP or bimetallic materials on direct propylene oxide synthesis”, NSF 1464630-PJ22, 06/2019-09/2020

Teaching Interests:

I passionately believe that teaching is a key and enjoyable part of being a new faculty member. I view teaching not only providing knowledge and information, but more about inspiring students who are future engineers, scientists and professors. I am excited about the opportunity to teach both undergraduate and graduate level classes as well as mentoring graduate and undergraduate students laboratory experiments. As a post-doc at Idaho National Laboratory and a research assistant professor at University of South Carolina, I have supervised graduate and undergraduate students in the catalysis and energy related projects with more than five publications.

Also, I have served as lecturer and teaching assistant for undergraduate and graduate courses during my PhD, post-doc and research assistant professor studies since 2011. I heavily participated in giving lectures, designing course contents and preparing grading exam questions and homework problems for courses including Chemical Process Principles, Chemical Engineering Thermodynamics, Heterogeneous Catalysis, and Chemical Engineering Undergraduate Laboratory. I am excited to share the fundamental science in chemical engineering and its significant impact on latest technology in industry and our daily life with undergraduate students to help cultivate their interests for science and engineering, and contribute to their education and professional career development.

Specific courses I would particularly enjoy teaching include Chemical Engineering Fundamentals, Chemical Process Principles, Chemical Reaction Engineering, Materials Characterization, and Chemical Engineering Thermodynamics at both undergraduate and graduate levels. In addition, with background of heterogeneous catalysis, I also plan to develop an elective course introducing the fundamentals of catalysis, including catalyst preparation and evaluation, reactor design, kinetic studies, mass/heat transfer limitations, and mechanism study using advanced characterization.