Skip Navigation
Chemical, Biological & Materials EngineeringOU homepageChemical, Biological and Materials Engineering

Steven P. Crossley

Steven Crossley

Associate Professor
Sam A. Wilson Professor
Roger and Sherry Teigen Presidential Professor

Ph.D. Chemical Engineering (2009)
University of Oklahoma
B.S. Chemistry (2004)
Oklahoma City University 

Research Engineer, ConocoPhillips, 6/2009 to 9/2010.
Associate Engineer, ConocoPhillips, 9/2010 to 7/2011.

(405) 325-5930

Our group’s research is focused on the areas of heterogeneous catalysis, surface science, and nanotechnology. The overarching approach behind each of our projects is to understand the interaction between the catalyst composition and surface structure with the resulting reactivity for a given reaction of interest. By understanding the reaction intermediates responsible for activity and selectivity, better catalysts may be formulated and utilized for their appropriate applications. Techniques utilized to accomplish this task include catalyst synthesis, detailed characterization both in and ex situ, and reaction kinetics.

Characterization techniques utilized to accomplish this goal include temperature programmed techniques (TPDesorption, Reduction, and Reaction), X-ray photoelectron spectroscopy, X-ray diffraction, Scanning Electron Microscopy, Transition Electron Microscopy, in situ FT-IR and Raman spectroscopy, UV-Vis spectroscopy, and isothermal adsorption techniques. These techniques, when combined with catalyst synthesis and reaction kinetics, can be applied to a variety of industrially relevant topics, including the development of novel upgrading strategies for the production of renewable biofuels, conventional fuels, and the development of specialty chemicals from a variety of sources.

The same concept of combining understanding of surface intermediates with catalyst synthesis can lead to applications related to nanotechnology as well. The controlled growth and functionalization of carbon nanotubes, for example, can lead to the development of novel catalysts and sensors for the detection of toxic chemicals and explosives. This approach has led us to the development of novel interfacially active nanohybrids based on supported single walled carbon nanotubes. 

The world we live in is faced with several daunting challenges today. In order to meet the anticipated targets for the production of cellulosic and advanced biofuels, numerous advancements in technology and fundamental understanding are necessary at an extremely rapid rate. At the same time, environmental concerns drive increasingly stringent regulations placed on oil refiners forcing the requirement of innovative solutions to maintain economically favorable refining in the US. The fact that research in catalysis can help these critical areas as well as provide support to US military operations makes this an exciting time for research in this area.  

Current Projects:

Deactivation Studies Associated with Upgrading of Pyrolysis Oils:

The conversion of lignocellulosic biomass to transportation fuels is one of the greatest challenges in catalysis today. A common technique employed is to produce an intermediate product known as pyrolysis oils through the fast pyrolysis of biomass. Pyrolysis oils contain a variety of compounds with a multitude of functional groups and a broad distribution of molecular weights. The optimal catalytic upgrading strategy varies with the functionality and molecular weight of a molecule. For example, it may be desirable to condense light aqueous phase species, such as acetic acid, while larger species such as lignin oligomers would benefit from the opposite strategy of depolymerization and deoxygenation. For this reason, a single upgrading strategy with the entire stream of pyrolysis oil is met with severe challenges. Pyrolysis oil cannot be separated through conventional means of distillation due to the thermal instability. Instead, pyrolysis oil must be separated through either staged upgrading, sequential condensation of the vapors, solubility of various oxygenates in different phases of varying polarity, or size exclusion.

While recent efforts have been made to develop improved fundamental understanding of how individual model compounds present in pyrolysis oils react across specific catalysts, the separation techniques described above are not sufficient to a single compound from the complex mixture known as pyrolysis oil. Instead, a best-case scenario is to provide a stream rich in a specific type of compound, for example rich in acid, furanics, or phenolics. In addition to these complexities, inorganic impurities and char particles present problems for deactivation. This project aims to investigate the fundamental role of these impurities present in a species rich on deactivation kinetics as well as the mechanism. This will be accomplished through several catalytic tests in flow reactors combined with detailed post run and in-situ catalyst characterization.

Explosive Detection through Functionalized Carbon Nanotube Arrays:

An area of significant interest to the improvement of defense is the advanced detection of explosives, both military and non-military.  One of the primary challenges in prevention of terrorism is the advanced detection of non-military explosives. Due to the wide variety of materials that may be used to create explosives, a wide range of sensors must be utilized, making a single sensor material less valuable.

This project aims to create a multifunctional explosive detection sensor based on functionalized carbon nanotube arrays. Carbon nanotube arrays will be regionally functionalized with various groups that attract characteristics of a wide range of explosives. Coatings may also be implied to prevent the adsorption of specific molecules. Based on the reaction of these functional groups to various chemical compounds, differences in the I-V curve will be observed. By microspotting different polymer coatings on electrodes connected by SWNT arrays, greatly varying responses in current at a given voltage result upon the introduction of different gas species. By regionally functionalizing and creating multiple nano-arrays, a single micro-scale system could potentially serve as a sensor for thousands of molecules. Carbon nanotube based detection systems have recently shown the ability to detect specific explosives in the ppb range.

As a parallel goal surrounding this project, based on data from the various generated I-V curves, attempts to re-construct the original molecule will be conducted through the use of artificial neural networks and quantitative structure-activity relationships. Density functional theory calculations may be utilized to estimate the relative interactions of various explosive molecules with functionalized nanotubes. This could potentially allow a single sensor to serve not only as a detector for explosive molecules, but also the reconstruction and identification of this molecule through predictive capabilities based on the resulting I-V curves. Experience in the areas of nanotube growth and functionalization, characterization, and structure-property prediction will all be applied in this project to generate a promising detection system that can carry great potential. 


Selected Publications

Google Scholar

1.      Experimental and First-Principles Evidence for Interfacial Activity of Ru/TiO2 for the Direct Conversion of m-Cresol to Toluene. Taiwo Omotoso, Byeongjin Baek, Lars C. Grabow, Steven Crossley, ChemCatChem Accepted. doi:10.1002/cctc.201700157, 2017

2.      Hydrogenation of o-cresol on platinum catalyst: Catalytic experiments and first-principles calculations. Yaping Li, Zhimin Liu, Wenhua Xue, Steven P. Crossley, Friederike C. Jentoft, Sanwu Wang, Applied Surface Science  393, 212-220 2017

3.      A Systems-Level Roadmap for Biomass Thermal Fractionation and Catalytic Upgrading Strategies. Jeff Herron, Tyler Vann, Nhung Duong, Daniel Resasco, Steven Crossley, Lance Lobban, Christos Maravelias, Energy Technology, early view doi:10.1002/ente.201600147 2017

4.      Direct carbon-carbon coupling of furanics with acetic acid over Brønsted zeolites. Science Advances Abhishek Gumidyala, Bin Wang, Steven Crossley2, e1601072, 2016

5.      A new finding for carbon nanotubes in polymer blends: Reduction of nanotube breakage during melt mixing. Jiaxi Guo, Nicholas Briggs, Steven Crossley, Brian P. Grady, Journal of Thermoplastic Composite Materials 0892705716681835, 2016

6.      Selective ketonization of acetic acid over HZSM-5: The importance of acyl species and the influence of water. Abhishek Gumidyala, Tawan Sooknoi, and Steven Crossley, Journal of Catalysis, 340, 76-84, 2016.

7.      C-C Coupling for Biomass-Derived Furanics Upgrading to Chemicals and Fuels. Tuong Bui, Steven Crossley, and Daniel E. Resasco, in Chemicals and Fuels from Bio-Based Building Blocks, 431-494, 2016.

8.      Zeolite-catalysed C–C bond forming reactions for biomass conversion to fuels and chemicals. Daniel E. Resasco, Bin Wang, and Steven Crossley, Catalysis Science & Technology, 6(8), 2543-2559, 2016.

9.      Rapid growth of vertically aligned multi-walled carbon nanotubes on a lamellar support. Nicholas Briggs, and Steven Crossley RSC Advances, 5(102), 83945-83952, 2015.

10.   Decoupling HZSM‐5 Catalyst Activity from Deactivation during Upgrading of Pyrolysis Oil Vapors, Shaolong Wan, Christopher Waters, Adam Stevens, Abhishek Gumidyala, Rolf Jentoft, Lance Lobban, Daniel Resasco, Richard Mallinson, and Steven Crossley, ChemSusChem 8, no. 3, 552-559, 2015.

11.   Epitaxial Growth of ZSM-5@ Silicalite-1: A Core–Shell Zeolite Designed with Passivated Surface Acidity, Arian Ghorbanpour, Abhishek Gumidyala, Lars C. Grabow, Steven P. Crossley, and Jeffrey D. Rimer. ACS nano 9, no. 4, 4006-4016, 2015

12.   Implementation of concepts derived from model compound studies in the separation and conversion of bio-oil to fuel, Daniel E. Resasco, and Steven P. Crossley. Catalysis Today 257, 185-199, 2015.

13.   Multiwalled Carbon Nanotubes at the Interface of Pickering Emulsions Nicholas M. Briggs, Javen S. Weston, Brian Li, Deepika Venkataramani, Clint P. Aichele, Jeffrey H. Harwell, and Steven P. Crossley. Langmuir 31, no. 48, 13077-13084, 2015

14.   Morphology of polystyrene/poly (methyl methacrylate) blends: Effects of carbon nanotubes aspect ratio and surface modification Guo, Jiaxi, Nicholas Briggs, Steven Crossley, and Brian P. Grady.  AIChE Journal 61, no. 10, 3500-3510, 2015

15.   Gluconic Acid from Biomass Fast Pyrolysis Oils: Specialty Chemicals from the Thermochemical Conversion of Biomass. Santhanaraj, Daniel, Marjorie R. Rover, Daniel E. Resasco, Robert C. Brown, and Steven Crossley ChemSusChem 7, no. 11 3132-3137, 2014.

16.   Generation of synergistic sites by thermal treatment of HY zeolite. Evidence from the reaction of hexane isomers, Anh T. To, Rolf E. Jentoft, Walter E. Alvarez, Steven P. Crossley, Daniel E. Resasco. Journal of Catalysis, 317, 11-21, 2014.

17.   Understanding the role of TiO2 crystal structure on the enhanced activity and stability of Ru/TiO2 catalysts for the conversion of lignin-derived oxygenates Taiwo Omotoso, Sunya Boonyasuwat, Steven Crossley, Green Chemistry, 2014,16, 645-652

18.    Ketonization of Carboxylic Acids: Mechanisms, Catalysts, and Implications for Biomass Conversion. Tu N. Pham, Tawan Sooknoi, Steven P. Crossley, Daniel E. Resasco, ACS Catalysis, 3(11), 2456-2473, 2013.

19.   Conversion of Guaiacol over Supported Ru Catalysts, Sunya Boonyasuwat, Taiwo Omotoso, Daniel E. Resasco, Steven P. Crossley, Catalysis Letters 143 (8), 783, 2013.

20.   Direct Conversion of Triglycerides to Olefins and Paraffins over Noble Metal Supported Catalysts, Martina Chiappero, Phuong Thi Mai Do, Steven Crossley, Lance L. Lobban, Daniel E. Resasco, Fuel, 90 (3), 1155-1165, 2011.

21.   Catalytic Conversion of Anisole over HY and HZSM-5 Zeolites in the Presence of Different Hydrocarbon Mixtures, Teerawit Prasomsri, Anh T. To, Steven Crossley, Walter E. Alvarez, Daniel E. Resasco, Applied Catalysis B: Environmental, 106(1-2), 204-211, 2011.

22.   Solid Nanoparticles that Catalyze Biofuel Upgrade Reactions at the Water/Oil Interface, Steven P. Crossley, Jimmy Faria, Min Shen, Daniel E. Resasco, Science, 327, 68-72, 2010.

23.   Etherification of 2-methylpentanal on Supported Palladium Catalysts, Trung Pham, Steven P. Crossley, Tawan Sooknoi, Lance L. Lobban, Daniel E. Resasco, Richard G. Mallinson, Applied Catalysis A: General, 379 (1-2), 135-140, 2010.

24.   Challenges and Opportunities for Catalysis Research in Biofuel Refining, Daniel E. Resasco, Steven Crossley, AIChE CEP, 105(5), 11, 2009.

25.   Molecular Engineering Approach in the Selection of Catalytic Strategies for Upgrading of Biofuels, Daniel E. Resasco, Steven P. Crossley, AIChE Journal, 55(5), 1082-1089, 2009.

26.   Activity Inhibition By Nitrogen Compounds in the Simultaneous Hydrogenation of Polyaromatic Compounds over NiMo/Al2O3 Catalyst in the Presence of Sulfur, Andrea R. Beltramone, Steven Crossley, Daniel E. Resasco, Tushar Choudhary, and Walter E. Alvarez. Catalysis Letters, 123, 181-185, 2008.

27.   A Novel Micropyrolyis Index (MPI) to Estimate Sooting Tendency of Fuels, Steven P. Crossley, Walter E. Alvarez, Daniel E. Resasco. Energy and Fuels, 22(4), 2455-2464, 2008.

28.   Catalytic Strategies for Improving Specific Fuel Properties, Phuong Do, Steven Crossley, Malee Santikunaporn, and Daniel E. Resasco, Catalysis (Special Periodical Reports) Royal Society of Chemistry, 20, 33-64, 2007