(6ay) Mixed-Metal-Oxide Redox-Catalyst for Shale-Oil and Gas Conversion

Research Assistant Professor (NC Statue University)

Postdoctoral Research: Chemical Looping Redox Catalyst

Chemical Looping-Oxidative Dehydrogenation (CL-ODH) of Light Paraffins and Naphtha: I co-invented multiple redox-catalysts for the oxidative dehydrogenation of light hydrocarbons and naphtha. This chemical-looping approach permits conversion of low-value/difficult-to-transport shale-gas and oil fractions into valuable commodity chemicals and liquid fuels. The CL-ODH process works by using the lattice oxygen of a redox “catalyst” to selectively combust hydrogen produced by thermal cracking. Regeneration of the redox-catalyst oxygen produces enough heat to drive the reaction without carbon-intensive, high-temperature furnaces. My research has demonstrated that this approach can give high yields and selectivity without significant dilution typically needed in co-feed ODH. I also developed kinetics for the design of a pilot unit. I am currently supporting follow-up research on adapting the material to work at low temperatures, where thermal cracking is kinetically and thermodynamically limited. If successful this will enable cheap, modular reactors that can convert stranded natural gas liquids for easy transport.

Syngas Production: Chemical looping reforming (CLR) replaces the gaseous oxygen needed for partial oxidation reforming with the lattice oxygen of a redox catalyst. CLR can improve the efficiency of Gas-to-liquid (GTL) processes vs. conventional reforming and permit small scale implementation. I formulated and characterized a novel core-shell redox catalyst for CLR of methane to syngas. My research shows that there are four distinct reaction regions for this type of catalyst, which have subsequently been observed in several related systems. My research also shows that the selectivity of a redox catalyst with high internal oxygen mobility is determined by the types of oxygen species available at the redox catalyst surface.

Thesis Research:

PhD Dissertation: “Nano-Particle Supported Catalyst”Advised by Dr. Helena Hagelin-Weaver in the Department of Chemical Engineering at the University of Florida

The oxidative coupling of 4-methyl-pyridines to 4,4′-Dimethyl-2,2′-bipyridine is a green chemistry process and a useful probe reaction for palladium catalysts. Pd on metal oxide supports had previously been reported as inactive for this reaction. I synthesized and characterized multiple palladium catalysts for this selective oxidation. The results showed that “inert” nano-particle metal oxide supports can induce similar behavior in platinum group catalysts typically ascribed to oxides with strong metal support interactions with correspondingly high activity.

Research and Funding Successes: I have authored or co-authored 20 refereed articles on a variety of catalytic reactions. I have supervised multiple research projects, mentoring over 12 graduate and undergraduate researchers, and have participated in the writing of 8 proposals, including as a named Co-PI. I co-invented a novel chemical looping ODH technology which secured a $3.8 million overall plus up from ARPA-E. My work has led to four patent applications, 2 of which have been licensed.

Future Direction: Catalysis is the classic means of “process intensification” in reaction engineering, but new insights into catalyst performance by mechanistic studies of real, practical catalysts is needed to keep pace with growing demands for cleaner energy and chemicals worldwide. My research on both supported platinum-group metal and mixed-metal-oxide redox catalysts will contribute to improved mechanistic understanding of greener, lower-emission catalytic processes. My future research will focus upon bridging the gap between real-world catalyst performance and fundamental studies on model systems. The goal of this emphasis is to guide rational development of practical, cheaper, more active, and greener catalysts. I will also actively pursue multi-dispensary collaboration. For example, system modeling is valuable for evaluating the interaction between process economics and catalyst performance parameters. Model catalyst development and characterization in collaboration with computer simulation for determining catalyst mechanisms is also important.

Research Interests: Building on my experience in practical reaction experimentation and mechanistic characterization of commercially relevant catalysts, I plan to conduct research in three areas: I) Oxygen storage materials for emissions reduction catalyst; II) Mechanisms of oxygenate formation in hydrocarbon systems; III) Unburned hydrocarbon oxidation over true earth-abundant materials.

Rational design of oxygen storage materials for enhanced NOx reduction and advance combustion: Several emissions catalysts rely on “oxygen storage material” (OSM) supports. These materials allow the catalyst to oxidize hydrocarbons and CO in the presence of low pressure oxygen reducing agents for the suppression and or reduction of NO_x creation studies. Rational design of OSM’s has focused heavily on oxygen capacity at operating temperatures. Research on direct NO_x reduction catalysts have shown that other properties are impotent, but these studies have tended to limit studies to unrealistically low N₂ and O₂ concentrations, unrealistically high concentrations of reducing gas. My work will look at a fuller range of parameters, including oxygen-vacancy formation energies, internal oxygen transport rates and surface site pH. The principles developed will allow the rational design of improved emissions-abatement catalysts.

Mechanistic study of oxygenate formation: The creation of alcohols and other oxygenates from alkanes is simultaneously a desired energy conversion process and a nuisance. Unwanted oxygenates can entrain water, poison catalysts, and add complexity to separations. However, oxygenate formation in processes such as gas to liquids and steam cracking is not well understood. I plan to use n-butane dehydrogenation as a model system. My research will probe a variety of catalysts with differing selectivities for oxygenate to determine underlying mechanisms. My studies will include in-situ/operando measurements, as well as surface characterizations. This project will yield mechanistic insights that guide suppression of oxygenates, while potentially developing improved catalysts for on purpose oxygenate production and other processes.

True earth-abundant materials for deep oxidation of UHCs and CO: Novel, inexpensive mixed metal oxides will be used for deep oxidation of unburned hydrocarbons (UHCs) and carbon monoxide emitted in flue gases. Some redox catalysts, including Mg₆MnO₈ and SrMnO₃, have significant deep oxidation activity. These mixed oxides can exhibit better thermal stability and poisoning resistance than traditional platinum-group metal (PGM) catalysts, while potentially working well in very low partial pressures of oxygen. They can also be made more cheaply than typically proposed rare-earth oxides. Understanding the flexible properties of these earth-abundant metal oxides can guide improvement of coal and biomass energy conversion efficiency, while lowering catalyst costs.

Teaching Interests: I welcome the opportunity to teach graduate and undergraduate courses. I am qualified to teach any core undergraduate chemical-engineering courses and find teaching important to improving my own understanding fundamental aspects of my field. My background in applied, heterogeneous catalysis and redox-materials has given me skills and experiences particularly well suited to teaching undergraduate courses relating to mass balances, thermodynamics, kinetics, and design. I am also interested in teaching graduate-level courses in kinetics and surface science as well as special topic courses in catalysis and energy conversion. My approach to teaching has been molded by my experience as a TA, guest lecturer, as well as my supervision and mentoring of graduate and undergraduates in laboratory research. I have TA’d undergraduate students in thermodynamics and unit operations, and I have trained, mentored, and supervised over a dozen graduate and undergraduate students in their research, including setting research plans for three master students and a Ph.D. student. These mentoring interactions have included numerous international female and minority students. I am committed to pursuing further diversity through teaching and providing research opportunities.

Selected Publications

Seif Yusuf, Luke M. Neal, Vasudev Haribal, Madison Baldwin, H Henry Lamb, Fanxing Li. “Manganese silicate based redox catalysts for greener ethylene production via chemical looping–oxidative dehydrogenation of ethane.” Applied Catalysis B: Environmental, Applied Catalysis B: Environmental, In Press (2018);

Yusuf⁺, Luke M. Neal⁺, F. Li. “Effect of Promoters on Manganese Containing Mixed Metal Oxides for Oxidative Dehydrogenation of Ethane via a Cyclic Redox Scheme.” ACS Catalysis, 7: 5163−5173 (2017); (+Co-first authors);

Luke M. Neal⁺, S. Yusuf⁺, F. Li. “Oxidative Dehydrogenation of Ethane: A Chemical Looping Approach.” Energy Technology, 4: 1200 (2016); (+Co-first authors);

Luke M. Neal, A. Shafiefarhood, F Li. “Effect of Core and Shell Compositions on MeOx@La_ySr_1−yFeO₃ Core–Shell Redox Catalysts for Chemical Looping Reforming of Methane.” Applied Energy 157, 391–398 (2015);

Luke M. Neal, A. Shafiefarhood, F. Li. “Dynamic Methane Partial Oxidation Using an Fe₂O₃@La_0.8Sr_{0. 2}FeO_3-δ Core–Shell Redox Catalyst in the Absence of Gaseous Oxygen.” ACS Catalysis, 4: 3560–3569 (2014);

Luke M. Neal, M. Everett, G. Hoflund, H. Hagelin-Weaver. “Characterization of Palladium Oxide Catalysts Supported on Nanoparticle Metal Oxides for the Oxidative Coupling of 4-Methlypyridine.” Journal of Molecular Catalysis A: Chemical, 335: 210-22 (2011);

Luke M. Neal, S. D. Jones, M. L. Everett, G. B. Hoflund, H. E. Hagelin-Weaver. “Characterization of Alumina-Supported Palladium Oxide Catalysts in the Oxidative Coupling of 4-Methylpyridine.” Journal of Molecular Catalysis A: Chemical, 325: 25-35 (2010).

Patent Applications:

Fanxing Li, Luke M. Neal, Junshe Zhang. “Redox Catalysts for the Oxidative Cracking of Hydrocarbons, Methods of Making, and Methods of Using.” PCT/US17/51,157 (2017).

Li, Luke M. Neal. “Ethylene Yield in Oxidative Dehydrogenation of Ethane and Ethane Containing Mixtures.” US 15/422,743 (2017);

J.A. Sofranko, F. Li, F. Li, Luke M. Neal. “Oxygen Transfer Agents for the Oxidative Dehydrogenation of Hydrocarbons and Systems and Processes Using the Same.” US 62/054,424 (2015).