(6kn) Sustainability towards the Future:bridging the gap between catalysis science and reaction engineering

Catalysis science is the central component and primary driver for sustainable chemical and energy production in the future. The ongoing transition from fossil-based resources to alternative sources, such as biomass and shale gas, urgently requires the development of next-generation catalysts and catalytic processes. To move forward, it is imperative to bridge the relatively wide gap between fundamental research of catalysis science and the ability to transfer knowledge to practical innovation, which is essentially based on the discipline of chemical reaction engineering. My research program will address these forefront challenges by developing highly selective and coke-resistant catalysts for methane conversion to C₂ oxygenates and biomass transformation to premium quality aviation fuels.

The modern-day catalysis science emphasizes the precise synthesis of catalytic materials (e.g. mesoporous and zeolite supports), dynamic characterization under working conditions (e.g. in situ/operado and ambient pressure approaches), and identification of active site requirements. Chemical reaction engineering (CRE), on the other hand, aims at investigating and optimizing catalytic reactions to reach the most optimal scaled-up reactor design, which typically includes the interactions between intrinsic kinetics with flow phenomena, mass and heat transfer. The key factor to bridging the gap between catalysis science and CRE is to investigate structure-activity relationships of heterogeneous catalysts and determine turnover frequency normalized by well-defined active sites under dynamic working conditions, followed by modeling of mirco- and macro-kinetics of heterogeneous catalytic reactions. This experimental contribution will be the primary focus in my future research group. Since a rich meta-data library exists for catalytic materials and catalyst/reactor performance, data science tools, like machine learning, reinforcement learning and artificial intelligence, may discover hidden trends and periodicities within catalysis data and reactor performance, and thus shorten the development time for next-generation of catalysts. These targets require the combination of controlled materials synthesis, in situ/operado characterization, precise measurements of isotopic kinetics, and rigorous mathematical modeling. The above research efforts in my research group will be fostered by collaboration with professionals of nanotechnology, first-principles and data science, which will leverage multi-disciplinary research to modern catalysis science and reaction engineering research.

My research group will focus on developing transitional-ready catalytic processes with excellent activity of reactants, selectivity towards target products, and turnover frequency over well-defined active sites and stability with long catalyst lifetime for a sustainable future by bridging the gap between catalysis and reaction engineering.

Future Research Directions:

• Conversion of Methane to C₂ Oxygenates (e.g. ethanol, ethylene oxide) over Highly Selective and Coke-Resistant Catalytic Materials
• Conversion of Algae to Premium Quality Bio-Jet Fuels over Robust Bifunctional Catalysts
• Data Science for Reactor Safety and Modeling of Complex Catalytic Kinetics

Successful Proposals:

1. “Direct Catalytic Oxidation of Methane to Liquid Oxygenates,” (PI: Dr. Arvind Varma) $353,950, 10/2017 - 9/2022; NSF; part of Engineering Research Center titled “Center for Innovative and Strategic Transformation of Alkane Resources (CISTAR)”.
2. “Catalyst Design and Reactor Runaway: Selective Oxidation of Alcohols,” (PI: Dr. Arvind Varma) $50,000, 7/2019 - 6/2021 Purdue Process Safety & Assurance Center (P2SAC)

Selected Projects:

Catalytic Nonoxidative Coupling of Methane (NOCM)

• Designed, prepared (wet impregnation), characterized (ICP, XRD, XPS, EDX, etc.) and tested Pt-Bi bimetallic catalysts
• Achieved over 90% selectivity to C₂ species from methane coupling over the new catalyst
• Proposed the explanation of the coke-resistant role of Bi promoter by conducting mechanistic investigations of the above catalyst, including DFT calculations, TPO, TPR and TPSR

Parametric Sensitivity in Chemical Reactors for Selective Oxidation of Alcohols

• Measured differential kinetics for methanol selective oxidation in a fixed-bed reactor
• Gave instructions for the control of reactor stability by developing a new kinetic and reaction model including heat transfer and parametric sensitivity

Selected Patents: - out of 20 patents/patent applications

1. Yang Xiao and Arvind Varma, Non-oxidative Production of Hydrocarbon from Methane, U.S. Patent (officially granted), US20190084904A1, September 19, 2018.
2. Yang Xiao and Arvind Varma, Method of Producing Formaldehyde from Methanol, U.S. Patent (officially granted), US20190194106A1, December 19, 2018.
3. Yang Xiao and Arvind Varma, Catalytic Deoxygenation of Bio-Oils Using Methane, U.S. Patent, No. US10023809 B2, July 17, 2018.

Selected Publications: - out of 22 peer-reviewed journal papers

1. Yang Xiao, Yuan Wang and Arvind Varma, Low-Temperature Selective Oxidation of Methanol over Pt-Bi Bimetallic Catalysts, Journal of Catalysis, 2018, 363, 144-153.
2. Yang Xiao and Arvind Varma, Highly Selective Nonoxidative Coupling of Methane over Pt-Bi Bimetallic Catalysts, ACS Catalysis, 2018, 8 (4), 2735-2740.
3. Yang Xiao, Jeffrey Greeley, Arvind Varma, Zhi-Jian Zhao and Guomin Xiao, An Experimental and Theoretical Study of Glycerol Oxidation to 1,3-Dihydroxyacetone Over Bimetallic Pt-Bi Catalysts, AIChE Journal, 2017, 63 (2), 705-715. (as Most Read Article)
4. Yang Xiao and Arvind Varma, Conversion of Glycerol to Hydrocarbon Fuels via Bifunctional Catalysts, ACS Energy Letters, 2016 1 (5), 963-968.

Teaching Interests:

Because of maintaining passion for teaching, I actively sought to build my repertoire of teaching skills to prepare for pursuing my career goal as a professor. In Spring 2019, I taught four lectures at one of our core chemical engineering courses for graduate students - Chemical Reaction Engineering (ChE660) in the Davidson School of Chemical Engineering of Purdue University. Those lectures include Experimental methods in catalytic kinetics, Stability & multiplicity of reactors, and Heterogeneous models for packed-bed reactors. Furthermore, I published a teaching-related journal article “Applications of Chemical Simulation Softwares in the Course of Transport Phenomena” (Chemical Industry Times, 2012, 26(10), 53-59), which describes how we can use powerful computer tools to facilitate teaching. In addition to being a co-instructor or teaching assistant in the classroom, I have also mentored more than 10 undergraduate students on research since 2010 when I started my graduate school. Most of them have published co-author peer-reviewed papers, and continued their own research career in prestigious graduate schools in the U.S. As a senior research associate in Dr. Varma’s lab, I also co-mentored three graduate students in the past 3 years. I am glad to see that now they can work relatively independently, making great progress on research and preparing manuscripts for peer-reviewed journals.

My education, research and teaching experiences have prepared me to teach the core courses, including Thermodynamics, Chemical Reaction Engineering/Reactor Design and Mathematical Methods in Chemical Engineering, in the Department of Chemical Engineering. Additionally, since data science is becoming increasingly critical in chemical engineering, I am interested in developing new undergraduate elective or graduate-level courses such as Data Science for Chemical Engineering and Methods in Catalysis Research to incorporate emerging data science topics into chemical engineering. I believe my great passion for teaching, various past teaching experiences, strong academic background and communication skills will make me an excellent teacher.