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Photo of Nick Thornburg in a laboratory setting

Nick Thornburg

Postdoctoral Researcher - Chemical Reaction Engineering & Heterogeneous Catalysis

Nicholas.Thornburg@nrel.gov | 303-275-4885
Orcid ID http://orcid.org/0000-0002-4680-2733

Research Interests

  • Lignin depolymerization and upgrading to value-added commodity and fine chemicals

  • Heterogeneous catalyst design, synthesis, and characterization

  • Particle-scale chemical reaction engineering and transport phenomena

  • Separations process development for fractionation of lignin depolymerization products

  • Formulation of bio-derived chemical products and multifunctional materials

  • Development of in situ active site titration techniques

  • Covalent surface modification of catalysts and other multifunctional materials

Areas of Expertise

  • Heterogeneous catalyst synthesis and design

  • Organometallic synthesis and covalent grafting

  • Chemical kinetics of liquid-phase reaction systems

  • Chemical reaction engineering and reactor design

  • Chemical product design

  • Transport phenomena and multiscale modeling

  • Gas chromatography mass spectrometry (GC-MS) and gas chromatography flame ionization detector (GC-FID)

  • UV-visible (UV-vis), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopies

  • Numerical methods and non-linear optimization for experimental data fitting

Education

  • Ph.D., Chemical Engineering, Northwestern University, 2017

  • B.S., Chemical Engineering, Washington University in St. Louis, 2012

Professional Experience

  • Postdoctoral Researcher, National Renewable Energy Laboratory (NREL), National Bioenergy Center (NBC), 2017–present

  • Polymer Product Design Intern, 3M, Corporate Research Materials Laboratory (CRML), 2015

  • Environmental Remediation Intern, ARCADIS U.S., Inc., 2011

  • RPP Intern, NREL, NBC, 2010

Featured Publications

  1. "Hybrid Approach for Selective Sulfoxidation via Bioelectrochemically Derived Hydrogen Peroxide over a Niobium(V)–Silica Catalyst," ACS Sustainable Chemistry & Engineering (2018)

    Schematic of a hybrid microbial electrochemical cell (MEC) inorganic catalytic system for wastewater valorization. At the left is an MEC unit (light blue box), illustrating a synthetic wastewater feed stream entering the unit at the bottom left (red arrow pointing to right), where it contacts an anode biofilm (gray box with green film layer at left) and effluent exiting at top left (red arrow pointing to left). An inset of the anode biofilm on the left-hand side illustrates the consumption of acetate medium (CH3COO-) to a carbon dioxide (CO2) and a proton (H+). On the right-hand side of the MEC unit, hydrogen peroxide (H2O2) effluent exits the unit at the top right (red arrow pointing to right), while phosphate buffer is fed at the bottom right (red arrow pointing left). In between these streams is a cathode (stone-colored block), with an inset depicting the electrochemical reaction of oxygen (O2) from air and an electron (e-) converting to a hydrogen peroxide (H2O2) molecule. The cathode is connected to the anode at the top of the MEC unit via a voltage source, labeled with the flow of an electron (e-). On the right-hand side of the graphic, the H2O2 effluent from the MEC enters a reactor (light blue box, feed entrance at top left with red arrow pointing to right). The reactor contains an inorganic niobium(V)-silica catalyst illustrated in an inset cartoon at the right. The H2O2 and catalyst convert the molecule 4-hydroxythioanisole (chemical structure and feed stream at reactor top) to 4-hydroxymethylphenyl sulfoxide (chemical structure and effluent stream at reactor top right). At the bottom of the graphic are the words: Microbial electrochemical cell to Inorganic Catalysis to Value Added Chemicals.
  2. "Consequences of Confinement for Alkene Epoxidation with Hydrogen Peroxide on Highly Dispersed Group 4 and 5 Metal Oxide Catalysts," ACS Catalysis (2018)

    The visual abstract depicts three figures. The left shows the ultraviolet-visible light absorbance spectra (200-550 nm wavelength range) for tantalum (Ta, orange lines), niobium (Nb, black lines), and titanium (Ti, blue lines) silicate catalysts of types M-BEA (bottom three spectra) and M-SiO2 (top three spectra) in the presence of hydrogen peroxide (H2O2) oxidant. Blue text below the figure reads Similar Reactive Intermediates…, indicating that all catalysts contain similar chemical intermediates for the selective epoxidation of styrenic alkenes. The center shows, at the top, an illustration of a micropore surrounding a metal oxide site in BEA zeolite (depicted as -Si-O-M-O-Si- chemical bonds within a circular arc labeled micropore). This catalyst cartoon sits above a chemical reaction arrow and the oxidizing reagent hydrogen peroxide, indicating the catalytic transformation of styrene (C8H8) to styrene oxide (C8H8O). Below this reaction scheme are two gear-shaped wheels. The top wheel, blue, is labeled Metal Identity in the center and has two counterclockwise arc arrows moving from right to left connecting elements Ta - Nb - Ti. The bottom wheel, orange, is labeled Pore Size in the center and has one clockwise arc arrow moving from left to right connecting 5.4 nm M-SiO2 - 0.7 nm M-BEA. The right shows a kinetic plot of Activation Barrier vs. Charge Transfer Energy for six catalysts plotted along two lines: the lower line connects Ti-BEA, Nb-BEA, and Ta-BEA from bottom-left to middle-right, while the upper line connects Ti-SiO2, Nb-SiO2, and Ta-SiO2 from middle-left to top-right. Two reversible arrows connect the lower and upper lines, illustrating the similar trends. Orange text below the figure reads Stabilization from Micropores…, indicating that the M-BEA catalysts have lower activation barriers compared to M-SiO2 catalysts due to stabilization of reactive intermediates inside of BEA's micropores.
  3. "Rate and Selectivity Control in Thioether and Alkene Oxidation with H2O2 over Phosphonate-Modified Niobium(V)–Silica Catalysts," ChemCatChem (2017)

    Visual abstract illustrating a catalyst undergoing competing oxidation reactions with H2O2 oxidant. A grey sphere in the center represents an SiO2 particle; it is decorated above and below with isolated NbV oxide sites, which facilitates the oxidation of thioanisole to methyl phenyl sulfone (using two H2O2 molecules) and is shown in the lower right and labeled 'radical' in red, or separately the oxidation of cyclohexene to cyclohexane oxide and cyclohexane diol (using one H2O2 molecule), which is shown in the upper right and labeled 'direct' in green. When the NbV sites are covalently modified with phenylphosphonic acid (Ph-P-OH(=O)-O-NbV-SiO2), thioanisole partially oxidizes to selectively form methyl phenyl sulfoxide (using one H2O2 molecule), which is shown in the lower left and labeled 'major product' in pink. Cyclohexene unselectively oxidizes to several radical-derived products (using two H2O2 molecules), which is shown in the upper left and labeled 'major product' in blue.
  4. "Synthesis-Structure-Function Relationships of Silica-Supported Niobium(V) Catalysts for Alkene Epoxidation with H2O2," ACS Catalysis (2016)

    Visual abstract illustrating synthesis-structure-function relationships among silica-supported NbV oxide catalysts. In the center is a grey sphere labeled 'mesoporous SiO2'. The 'Synthesis' portion (in blue) in the upper right, illustrates a generic NbV complex precursor with arrows pointing to final NbV sites on the grey spherical SiO2 particle, made by either grafting, co-condensation, or impregnation methods. The 'Structure' portion (in green) in the lower center lists diffuse reflectance UV-visible and X-ray absorption near-edge spectroscopies as characterization tools. The 'Function' portion (upper left) in pink illustrates an in situ poisoning technique carried out during the epoxidation of cis-cyclooctene with H2O2 oxidant. NbV sites poisoned by phenylphosphonic acid (Ph-P-OH(=O)-O-NbV-SiO2) are illustrated not to carry out chemical reaction to the cyclooctane oxide and water (H2O) products.
  5. "MOFs and their grafted analogues: regioselective epoxide ring-opening with Zr6 nodes," Catalysis Science & Technology (2016)

    Visual abstract illustrating three different zirconium (ZrIV) oxide-based catalysts. On the left is a NU-1000 metal-organic framework (MOF), containing green Zr6 clusters arranged in three-dimensional, repeating and parallel hexagonal porous channels. The center shows Zr6 clusters (represented by a green cube) covalently attached to phosphonate-modified silica gel (P(=O)2(OH)-SiO2). The right shows isolated, singular ZrIV sites on silica gel (ZrIV-SiO2). The three catalysts are shown to carry out the ring-opening of 1,2-epoxyoctane with isopropanol to give two products, a primary C11 alcohol and a secondary C11 alcohol.
  6. "Catalyst Structure and Substituent Effects on Epoxidation of Sytrenics with Immobilized Mn(tmtacn) Complexes," Applied Catalysis A: General (2016)

    Visual abstract illustrating the organic di-manganese complex [Mn2O3(tmtacn)2]2+ (tmtacn = 1,4,7-trimethyl-1,4,7-triazacyclononane), drawn at the left, being tethered to a carboxylic acid-functionalized silica gel surface (i.e., SiO2-R-COOH) in the center of the illustration . The immobilized manganese complex undergoes chemical activation with hydrogen peroxide (H2O2, in red) to then carry out catalytic epoxidation of various para-functionalized styrene compounds, illustrated on the right-hand side as R-C6H4-CH=CH2 converting to the corresponding epoxide along a large black curved arrow pointing from top to bottom. The oxygen atom in the epoxide product is colored red to indicate that it originates from the red H2O2 oxidant.
  7. "Stable Metal-Organic Framework-Supported Niobium Catalysts," Inorganic Chemistry (2016)

    Visual abstract illustrating the synthesis and function of a catalyst material. On the left, a metal-organic framework (MOF) support composed of 6 hexagonally-ordered 3-dimensional porous channels in red and green is shown as part of a grey ring. This support is functionalized with niobium (Nb) metal cations through two methods, 'AIM' (atomic layer deposition (ALD) inside of a MOF) and 'SIM' (solution impregnation). The Nb is drawn as a purple sphere above a large black arrow pointing right with 'AIM and SIM' listed below to indicate the two different chemical modification procedures. To the right of the arrow point, the Nb-functionalized MOF is drawn as purple spheres overlaying at the corners of the hexagon channels. A large curved white arrow with black outline points from top to bottom and swoops through the hexagon channel to illustrate catalytic transformation of cyclohexene by hydrogen peroxide (H2O2) oxidant, forming oxygenated products cyclohexane oxide, trans-1,2-cyclohexanediol, cyclohexenol, cyclohexenone, and byproduct water.
  8. "Periodic Trends in Highly Dispersed Groups IV and V Supported Metal Oxide Catalysts for Alkene Epoxidation with H2O2," ACS Catalysis (2015)

    Visual abstract illustrating a periodic array of heterogeneous oxidation catalysts made from Group IV (Ti, Zr, Hf) and Group V (V, Nb, Ta) metal cations. On the left, catalysts are shown to be synthesized by attaching metal-calixarene coordination complexes (abbreviated 'calix-MClx') to spherical silica particles (represented as 'SiO2' in a grey sphere). The resulting catalysts (arrow pointing right) are illustrated in a 3x2 grid mimicking Groups IV and V of the periodic table, where metal cations are drawn to have three bonds to the bottom of a rectangle representing its element, and an additional –OH group (Ti, Zr, Hf) or =O group (V, Nb, Ta). On the right, the catalytic transformation of cyclohexene with H2O2 oxidant is illustrated using a reaction arrow pointing to five chemical product structures drawn: cyclohexane oxide, cyclohexane diol, cyclohexenol, cyclohexenone, and water (H2O).
  9. "Nickel Cerium Olivine Catalyst for Catalytic Gasification of Biomass," Applied Catalysis B: Environmental (2013)

    Visual abstract illustrating a typical process for the catalytic gasification of biomass. At left, a picture of dried corn crops labeled ‘Biomass’ is shown to convert to either ‘pyrolysis vapors’ or ‘char’ along two parallel pathways, indicated with blue arrows pointing right with a corresponding rate constant k1 labeled underneath. From either pyrolysis vapors or char, two additional conversion pathways with rate constant k2 are illustrated as two more arrows pointing right, one which forms carbon monoxide (CO) and hydrogen (H2) and another which forms 2-carbon- to 5-carbon-containing radicals (C2-5 R). These C2-5 radicals further react along two additional arrows pointing right to form CO and H2 (with rate constant k3) or polyaromatic hydrocarbons (PAH, with rate constant k4), for which benzene (C6H6) and naphthalene (C10H8) are drawn as examples. The four conversion processes illustrated for k2, k3, and k4 are labeled generally as ‘Gasification’, which is shown in green text at the bottom center.

Awards and Honors

  • NREL Employee of the Month, Excellence in Chemical Reactor Design, Chemical Process Safety, and Leadership in Promoting a Positive Safety Culture (2018)

  • Distinguished Graduate Researcher Award, Chemical & Biological Engineering Department, Northwestern University (2016)

  • W. L. Gore Research Fellowship Grand Prize Winner (2015)

  • George Thodos Teaching Assistant Award, Chemical & Biological Engineering Department, Northwestern University (2015)

  • NCAA Academic All-American, Men’s Swimming (2009–2012)