Matthew Neurock

• University of Minnesota

The requirement for C 2 H 2 concentrations below 2 parts per million (ppm) in gas streams for C 2 H 4 polymerization necessitates its semihydrogenation to C 2 H 4 . We demonstrate selective chemical looping combustion of C 2 H 2 in C 2 H 4 -rich streams by Bi 2 O 3 as an alternative catalytic pathway to reduce C 2 H 2 concentration below 2 ppm. Bi...

Selective C-H bond activation is one of the most critical molecular transformations in synthesizing chemicals, pharmaceuticals, and natural product intermediates with broad applications. Recent efforts have focused on developing electrocatalytic mediators that rapidly and selectively activate specific C-H bonds. These mediated activations offer mul...

Aqueous solutions containing both the strong oxidant, peroxydisulfate (S2O82‒), and the strong reductant, oxalate (C2O42‒), are thermodynamically unstable due to the highly exothermic homogeneous redox reaction: S2O82‒ + C2O42‒ ® 2 SO42‒ + 2 CO2 (DG0 = −490 kJ/mol). However, at room temperature, this reaction does not occur to a significant extent...

Aqueous solutions containing both the strong oxidant, peroxydisulfate (S2O82‒), and the strong reductant, oxalate (C2O42‒), are thermodynamically unstable due to the highly exothermic homogeneous redox reaction: S2O82‒ + C2O42‒ ® 2 SO42‒ + 2 CO2 (DG0 = −490 kJ/mol). However, at room temperature, this reaction does not occur to a significant extent...

The extent of charge transfer between adsorbed reactants and a catalyst surface plays a key role in determining binding energy and catalytic activity. Here, we describe the technique of ‘isopotential titration’ (IPT) to quantify the magnitude and direction of charge transfer between adsorbates and catalytic surfaces. The method used a ‘catalytic co...

This perspective provides the collective opinions of a dozen chemical reaction engineers from academia and industry. In this sequel to the “Vision 2020: Reaction Engineering Roadmap,” published in 2001, we provide our opinions about the field of reaction engineering by addressing the current situation, identifying barriers to progress, and recommen...

The growing global plastic waste challenge requires the development of new plastic waste management strategies such as pyrolysis that will enable a circular plastic economy. Pyrolyzed plastics thermally convert into a complex mixture of intermediates and products that includes their constituent monomers. Developing optimized, scalable pyrolysis rea...

Continued demand for polyolefins can be met by recycling plastic materials back to their constituent monomers, ethylene and propylene, via thermal cracking in a pyrolysis reactor. During pyrolysis, saturated polyolefin chains break carbon-carbon and carbon-hydrogen bonds, yielding a distribution of alkanes, alkenes, aromatic chemicals, light gases,...

Grafting metal cations to missing linker defect sites in zirconium-based metal-organic frameworks, such as UiO-66, produces a uniquely well-defined and homotopic catalytically active site. We present here the synthesis and characterization of a group of UiO-66-supported metal catalysts, M-UiO-66 (M = Ni, Co, Cu, and Cr), for the catalytic dimerizat...

Accelerating catalytic chemistry and tuning surface reactions require precise control of the electron density of metal atoms. In this work, nanoclusters of platinum were supported on a graphene sheet within a catalytic condenser device that facilitated electron or hole accumulation in the platinum active sites with negative or positive applied pote...

Alcohol oxidation is an important class of reaction that is traditionally performed under harsh conditions and most often requires the use of organometallic compounds or transition metal complexes as catalysts. Here, we introduce a new electrochemical synthetic method, referred to as reductive oxidation, in which alcohol oxidation is initiated by t...

Understanding heterogeneous catalysts is a challenging pursuit due to surface site nonuniformity and aperiodicity in traditionally used materials. One example is sulfated metal oxides, which function as highly active catalysts and as supports for organometallic complexes. These applications are due to traits such as acidity, ability to act as a wea...

Accelerating catalytic chemistry and tuning surface reactions requires precise control of the electron density of metal atoms. In this work, nanoclusters of platinum were supported on a graphene sheet within a catalytic condenser device that facilitated electron or hole accumulation in the platinum active sites with negative or positive applied pot...

Layered black arsenic (b-As) has recently emerged as a new anisotropic two-dimensional (2D) semiconducting material with applications in electronic devices. Understanding factors affecting the ambient stability of this material remains crucial for its applications. Herein, we use first-principles density functional theory calculations to examine th...

Accelerating catalytic chemistry and tuning surface reactions requires precise control of the electron density of metal atoms. In this work, nanoclusters of platinum were supported on a graphene sheet within a catalytic condenser device that facilitated electron or hole accumulation in the platinum active sites with negative or positive applied pot...

Layered black arsenic (b-As) has recently emerged as a new anisotropic two-dimensional (2D) semiconducting material with applications in electronic devices. Understanding factors affecting the ambient stability of this material remains crucial for its applications. Herein we use first-principles density functional theory (DFT) calculations to exami...

Homotopic sites in a well-controlled environment are not only ideal systems for mechanistic studies, but also allow optimal control of catalytic transformations. Sites having only a single metal cation and sites consisting of metal oxo complexes with few nickel (Ni) cations supported on the nodes of UiO-66 metal-organic framework (Ni-UiO-66) are st...

Precise control of electron density at catalyst active sites enables regulation of surface chemistry for the optimal rate and selectivity to products. Here, an ultrathin catalytic film of amorphous alumina (4 nm) was integrated into a catalytic condenser device that enabled tunable electron depletion from the alumina active layer and correspondingl...

Precise control of electron density at catalyst active sites enables regulation of surface chemistry for optimal rate and selectivity to products. Here, an ultrathin catalytic film of amorphous alumina (4 nm) was integrated into a catalytic condenser device that enabled tunable electron depletion from the alumina active layer and correspondingly st...

The water-gas shift (WGS) reaction rates per total mole of Au at 120 °C, 7% CO, 22% H2O, 8.5% CO2, 37% H2 decrease in the order Au/Anatase ∼ Au/Anatase001 (uniform anatase TiO2 single crystals with 64 per cent of the more {001} facets) ∼ Au/P25 ∼ Au/P25-WGC (obtained from the World Gold Council) ∼ Au/Rutile > Au/ZrO2 > Au/CeO2 > Au/ZnO when compare...

The direct, transition metal-catalyzed carboxylation of organohalides with carbon dioxide is a highly desirable transformation in organic synthesis as it utilizes feedstock chemicals and delivers carboxylic acids –among the most utilized class of organic molecules. Phenyl acetic acids, in particular, are privileged motifs that appear in many pharma...

The direct, transition metal-catalyzed carboxylation of organohalides with carbon dioxide is a highly desirable transformation in organic synthesis as it utilizes feedstock chemicals and delivers carboxylic acids –among the most utilized class of organic molecules. Phenyl acetic acids, in particular, are privileged motifs that appear in many pharma...

Metal-containing zeolites exhibit remarkable catalytic activity for hydrogenation owing to the synergistic interactions between acid and metal sites. In the aqueous phase, the presence of water and, in particular, hydronium ions, complicate the adsorption of H2 and organic substrates. It is shown how hydrated hydronium ions formed from zeolite Brøn...

Alkaline earth metal ions accelerate the breaking of cellulose bonds and control the distribution of products in the pyrolysis of lignocellulose to biofuels and chemicals. Here, the activation of cellulose via magnesium ions was measured over a range of temperatures from 370 to 430 ⁰C for 20 to 2000 milliseconds and compared with activation of cell...

Alkaline earth metal ions accelerate the breaking of cellulose bonds and control the distribution of products in the pyrolysis of lignocellulose to biofuels and chemicals. Here, the activation of cellulose via magnesium ions was measured over a range of temperatures from 370 to 430 ⁰C for 20 to 2000 milliseconds and compared with activation of cell...

The “magic methyl” effect – a dramatic boost in the potency of biologically active compounds from the incorporation of a single methyl group – provides a simple yet powerful strategy employed by medicinal chemists in the drug discovery process. Despite significant advances, methodologies that enable the selective C(sp3)–H methylation of structurall...

The “magic methyl” effect – a dramatic boost in the potency of biologically active compounds from the incorporation of a single methyl group – provides a simple yet powerful strategy employed by medicinal chemists in the drug discovery process. Despite significant advances, methodologies that enable the selective C(sp3)–H methylation of structurall...

The “magic methyl” effect – a dramatic boost in the potency of biologically active compounds from the incorporation of a single methyl group – provides a simple yet powerful strategy employed by medicinal chemists in the drug discovery process. Despite significant advances, methodologies that enable the selective C(sp3)–H methylation of structurall...

The “magic methyl” effect – a dramatic boost in the potency of biologically active compounds from the incorporation of a single methyl group – provides a simple yet powerful strategy employed by medicinal chemists in the drug discovery process. Despite significant advances, methodologies that enable the selective C(sp3)–H methylation of structurall...

Significance Highly abundant methane is vastly underutilized as a feedstock for chemicals and fuels reflecting its inertness. One seemingly attractive approach to methane utilization would be direct catalytic oxidative coupling of methane (OCM) with O 2 to produce ethylene, a valuable chemical feedstock. However, the exothermicity leads largely to...

The direct synthesis of hydrogen peroxide (H2 + O2 → H2O2) may enable low-cost H2O2 production and reduce environmental impacts of chemical oxidations. Here, we synthesize a series of Pd1Au x nanoparticles (where 0 ≤ x ≤ 220, ∼10 nm) and show that, in pure water solvent, H2O2 selectivity increases with the Au to Pd ratio and approaches 100% for Pd1...

Naturally occurring metals, such as calcium, catalytically activate the intermonomer β-glycosidic bonds in long chains of cellulose, initiating reactions with volatile oxygenates for renewable applications. In this work, the millisecond kinetics of calcium-catalyzed reactions were measured via the method of the pulse-heated analysis of solid and su...

p>The site-specific oxidation of strong C(sp3)-H bonds is of uncontested utility in organic synthesis. From simplifying access to metabolites and late-stage diversification of lead compounds to truncating retrosynthetic plans, there is a growing need for new reagents and methods for achieving such a transformation in both academic and industrial...

Solvents forming redox mediators The role of solvents participating directly in thermal catalytic reactions is clearer for homogeneous catalysis than for heterogeneous catalysis. Adams et al. studied the formation of hydrogen peroxide from hydrogen and oxygen on palladium nanoparticles by measuring the kinetic isotope effect and performing density...

Catalyst lifetime and product selectivity of methanol-to-olefins (MTO) catalysis on isostructural HSSZ-13 and HSAPO-34, possessing Brønsted acid sites of different acid strengths, are examined and interpreted to elucidate the role of acid strength in MTO catalysis with and without high-pressure H2 co-feeds. MTO catalysis without H2 cofeeds on HSSZ-...

Molecular interactions with both oxides and metals are essential for heterogenous catalysis, leading to remarkable synergistic impacts on activity and selectivity. Here, we show that the direct link between the two phases (and not merely being together) is required to selectively hydrogenate CO2 to methanol on catalysts containing Cu and ZrO2. Mate...

Naturally occurring metals such as calcium catalytically activate the inter-monomer β-glycosidic bonds in long chains of cellulose initiating reactions to volatile oxygenates for renewable applications. In this work, the millisecond kinetics of calcium catalyzed reactions were measured via the method of pulse-heated analysis of solid/surface reacti...

The small pore zeolite with the chabazite framework topology, SSZ-13, is found to be an active catalyst in the carbonylation of dimethyl ether (DME) to methyl acetate (MA). The production of MA over SSZ-13 after 24 hours on stream at 165 ˚C and 1 bar approaches that obtained from mordenite and is significantly higher than from ferrierite at compara...

Two-dimensional MoS2 is an excellent channel material for ultrathin field-effect transistors, but high contact resistance across the deposited metal-MoS2 interface continues to limit its full realization. Using atomic-resolution scanning transmission electron microscopy and first-principles calculations, we showed that deposited metals with a high...

Electrocatalytic activity for hydrogen evolution at monolayer MoS2 electrodes can be enhanced by the application of an electric field normal to the electrode plane. The electric field is produced by a gate electrode lying underneath the MoS2 and separated from it by a dielectric. Application of a voltage to the back-side gate electrode while sweepi...

Co-feeding water leads to a simultaneous attenuation of chain initiation and chain termination rates in HSSZ-13 catalyzed methanol-to-olefins (MTO) conversion. Density functional theory calculations and transient stoichiometric experiments support the plausibility of formaldehyde hydrolysis occurring over zeolitic Brønsted acid sites at MTO-relevan...

div> Electrocatalytic activity for hydrogen evolution at monolayer MoS2 electrodes can be enhanced by the application of an electric field normal to the electrode plane. The electric field is produced by a gate electrode lying underneath the MoS2 and separated from it by a dielectric. Application of a voltage to the back-side gate electrode while...

C-N cross-coupling is one of the most valuable and widespread transformations in organic synthesis. Largely dominated by Pd- and Cu-based catalytic systems, it has proven to be a staple transformation for those in both academia and industry. The current study presents the development and mechanistic understanding of an electrochemically driven, Ni-...

The use of polar aprotic solvents in acid-catalyzed biomass conversion reactions can lead to improved reaction rates and selectivities. We show that further increases in catalyst performance in polar aprotic solvents can be achieved through the addition of inorganic salts, specifically chlorides. Reaction kinetics studies of the Brønsted acid-catal...

div> C–N cross-coupling is one of the most valuable and widespread transformations in organic synthesis. Largely dominated by Pd- and Cu-based catalytic systems, it has proven to be a staple transformation for those in both academia and industry. The current study presents the development and mechanistic understanding of an electrochemically driv...

Scaled-up sodium-free Birch reductions The so-called Birch reduction is frequently used by chemists despite its daunting conditions: Pyrophoric sodium is dissolved in pure liquified ammonia to achieve partial reduction of aromatics. Peters et al. surveyed and then optimized small-scale electrochemical alternatives to devise a safer protocol that ca...

The selective formation of bio-aromatics from renewable sources to access greener alternatives to petroleum-derived aromatics is of great interest in the development of sustainable chemicals. An innovative and efficient bio-based route towards the formation of toluic acid using coumalic acid (or methyl coumalate) cycloaddition with bioavailable pro...

Two-dimensional molybdenum disulfide (MoS2) is an excellent channel material for ultra-thin field effect transistors. However, high contact resistance across the metal-MoS2 interface continues to limit its widespread realization. Here, using atomic-resolution analytical scanning transmission electron microscopy (STEM) together with first principle...

The repulsive lateral interactions that occur at the high coverages present on catalysts under reaction conditions are likely to exert a significant influence on the reaction energetics. The effect of such lateral interactions are explored for the synthesis of vinyl acetate monomer (VAM) on Pd(111) and Au/Pd(111) alloy model single-crystal catalyst...

Bismuth electrodes undergo distinctive electrochemically-induced structural changes in non-aqueous imidazolium ([Im]⁺) based ionic liquid solutions under cathodic polarization. In situ X-ray reflectivity (XR) studies have been undertaken to probe well-ordered Bi (001) films which originally contain a native Bi2O3 layer. This oxide layer gets reduce...

The use of organic solvents in biomass conversion reactions can lead to high rates and improved selectivities. Here, we elucidate the effects of organic solvent mixtures with water on the kinetics of acid-catalysed dehydration reactions of relevance to biomass conversion. Based on results from reaction kinetics studies, combined with classical and...

2-Pyrones, such as coumalic acid, are promising bio-based molecules that through Diels-Alder reactions can provide access to a wide range of bio-based chemicals, including molecules with functionality that are not easily accessible via convention-al petrochemical routes. A complete reaction network and kinetic parameters for three individual divers...

The selective production of aromatics from bio-based sources is an area of interest to expand the potential for greener alternatives to petroleum-derived chemicals. A scalable, efficient route to produce bio-based benzoates is demonstrated in up to 100 mol% yield by carrying out heterogeneous catalytic reactions in non-toxic bio-based solvents at 1...

Catalytic reactions of supercritical n-hexane and n-dodecane were studied over H-ZSM-5, H-Y and Al-MCM-41 at pressures between 4 and 6 MPa and temperatures between 558 and 748 K, using a combination of experimental and theoretical approaches. The primary reaction for n-hexane conversion over H-ZSM-5 was cracking, whereas the primary reaction over H...

A novel algorithm has been developed to achieve temporal acceleration during kinetic Monte Carlo (KMC) simulations of surface catalytic processes. This algorithm allows for the direct simulation of reaction networks containing kinetic processes occurring on vastly disparate timescales which computationally overburden standard KMC methods. Previousl...

Surface adsorption and activation of propene, to catalytically produce propene oxide, is the first step in the industrially important gas-phase epoxidation reaction. Motivated by the significant practical importance of this reaction, site-specific adsorption of propene on nanoparticulate titania-supported Au (Au/TiO2) has been systematically charac...

Direct gas-phase epoxidation of propene to propene oxide over a heterogeneous catalyst holds the potential to revolutionize production of one of the world's major commodity chemicals. New research into fundamental aspects of propene chemistry on nanoparticulate catalysts will help guide strategies for materials development. In the current study, Fo...

We report here theoretical evidence for an enhancement in CO activation to form C1 monomers at locations near growing hydrocarbon chains as a result of their ability to disrupt the dense monolayers of chemisorbed CO∗ present during Fischer–Tropsch synthesis (FTS). These previously unrecognized routes become favored at the high CO∗ coverages that pr...

Electronegative coadsorbates such as atomic oxygen (O*) and hydroxide (OH*) can act as Brønsted bases when bound to Group 11 as well as particular Group 8–10 metal surfaces and aid in the activation of X–H bonds. First principle density functional theory calculations were carried out to systematically explore the reactivity of the C–H bonds of meth...

We report experimental as well as theoretical evidence that suggest Au-CO complex formation upon the exposure of CO to active sites (step edges and threading dislocations) on a Au(111) surface. Room-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), transmission infrared spectroscopy, and density functional the...

Condensation and esterification are important catalytic routes in the conversion of polyols and oxygenates derived from biomass to fuels and chemical intermediates. Previous experimental studies show that alkanal, alkanol and hydrogen mixtures equilibrate over Cu/SiO2 and form surface alkoxides and alkanals that subsequently promote condensation an...

The noncovalent functionalization of graphene by small molecule aromatic adsorbates, phenanthrenequinone (PQ), is investigated systematically by combining electrochemical characterization, high-resolution interfacial X-ray scattering, and ab initio density functional theory calculations. The findings in this study reveal that while PQ deposited on...

The partial oxidation of model C2-C4 (acetic, propionic, and butyric) carboxylic acids on Au/TiO2 catalysts consisting of Au particles ∼3 nm in size was investigated using transmission infrared spectroscopy and density functional theory. All three acids readily undergo oxidative dehydrogenation on Au/TiO2. Propionic and butyric acid dehydrogenate a...

Infrared studies of Au/TiO2 catalyst particles indicate that charge transfer from van der Waals-bound donor or acceptor molecules on TiO2 to Au occurs via transport of charge carriers in the semiconductor TiO2 support. The ∆νCO on Au is shown to be proportional to the polarizability of the TiO2 support fully covered with donor or acceptor molecules...

Abstracts: * DDH AIChE 2014 FTS Selectivity Draft 2.pdf (65.7KB) - Uploading Abstracts

Proton transfer across single layer graphene is associated with large computed energy barriers and is therefore thought to be unfavorable at room temperature. Experiments, however, have not yet been performed to test this prediction. Here, we subject single layer graphene on fused silica to cycles of high and low pH and show that protons transfer r...

Proton coupled electron transfer reactions which are pervasive throughout electrochemistry control a number of energy conversion strategies. First-principles density functional theoretical calculations are used herein to examine proton coupled electron transfer between a homogeneous mononuclear polypyridyl–ruthenium catalyst used in the catalytic o...

The promotion of metal catalysts with partially oxidized oxophilic MOx species, such as ReOx-promoted Rh, has been demonstrated to produce Bronsted acid sites that can promote hydrogenolysis of oxygenate intermediates such as those found in biomass-derived species. A wide variety of alloy compositions and structures are examined in this work to inv...

The activation energies for the reaction of gas-phase ethylene with adsorbed acetate species on Au/ Pd(111) alloys are measured as a function of gold coverage in the alloy to probe the elementary steps in gold-palladium alloy catalyzed vinyl acetate monomer (VAM) synthesis. The activation energy decreases with increasing gold coverage in the alloy...

The oxidative-dehydrogenation of carboxylic acids to selectively produce unsaturated acids at the second and third carbons regardless of alkyl chain length was found to occur on a Au/TiO2 catalyst. Using transmission infrared spectroscopy (IR) and density functional theory (DFT), unsaturated acrylate (H2C=CHCOO) and crotonate (CH3CH=CHCOO) were obs...

Gold (Au) nanoparticles supported on reducible oxides such as TiO2 demonstrate exceptional catalytic activity for a wide range of gas phase oxidation reactions such as CO oxidation, olefin epoxidation, and water gas shift catalysis. Scientists have recently shifted their hypotheses on the origin of the reactivity of these materials from the unique...

Water increases Fischer-Tropsch synthesis (FTS) rates on Ru through H-shuttling processes. Chemisorbed hydrogen (H*) transfers its electron to the metal and protonates the O-atom of CO* to form COH* which subsequently hydrogenates to *HCOH* in the kinetically-relevant step. H2 O also increases the chain length of FTS products by mediating the H-tra...

Impact of Water on the Mechanism of Fischer-Tropsch Synthesis on Ru Catalysts David D. Hibbitts1, Brett T. Loveless1, Matthew Neurock2* and Enrique Iglesia1* 1Department of Chemical and Biomolecular Engineering, University of California at Berkeley, Berkeley, California 94720, United States 2Departments of Chemical Engineering and Chemistry,...

Increasing interests in the use of biorenewables feedstocks as alternatives to petroleum sources have promoted many of the recent studies in the literature on the dehydration, hydrogenolysis, decarbonylation and decarboxylation pathways of oxygenated intermediates derived from biomass. The selective dehydration and functionalization of polyols such...

The reaction pathways for the synthesis of vinyl acetate monomer (VAM) are explored on model palladium and gold–palladium alloy single crystal catalysts by combining experiments carried out in ultrahigh vacuum together with density functional theory calculations and Monte Carlo simulations. Previous work by Goodman has shown that both pure palladiu...

The partial oxidation of ethylene to form adsorbed acetate on a Au/TiO2 catalyst at temperatures as low as 370 K is reported here using Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectrometry (GC–MS) and density functional theory (DFT) calculations. Ethylene reacts with oxygen on Au/TiO2 to produce acetate on the TiO2 s...

Mechanistic assessments based on kinetic and isotopic methods combined with density functional theory are used to probe the diverse pathways by which C-H bonds in CH4 react on bare Pd clusters, Pd cluster surfaces saturated with chemisorbed oxygen (O*), and PdO clusters. C-H activation routes change from oxidative addition to H-abstraction and then...

The rates of reaction of acetate species adsorbed on a range of Au/Pd(111) alloys with gas-phase ethylene to form vinyl acetate monomer (VAM) were explored by monitoring the time dependence of the adsorbate coverages using infrared spectroscopy. It was found that the acetate species react directly to form VAM since the decrease in the coverage of a...

The unique interfacial sites of Au nanoparticles supported on TiO2 are known to catalyze the activation of oxygen and it's addition to small molecules including H2, CO, NO and propylene. Herein we extend these ideas and show that the unique Au-Ti dual perimeter sites that form at the Au/TiO2 interface can also catalyze more demanding C-H and C-O bo...