A5071068919- Catalytic Processes in Materials Science
- Advanced Combustion Engine Technologies
- Atmospheric chemistry and aerosols
- Catalysis and Oxidation Reactions
- Combustion and flame dynamics
- Ionic liquids properties and applications
- Biodiesel Production and Applications
- Chemical Thermodynamics and Molecular Structure
- Advanced Chemical Sensor Technologies
- Oxidative Organic Chemistry Reactions
- Heat transfer and supercritical fluids
- Thermochemical Biomass Conversion Processes
- Energetic Materials and Combustion
- Eicosanoids and Hypertension Pharmacology
- Analytical chemistry methods development
- History and advancements in chemistry
- Atmospheric and Environmental Gas Dynamics
- Distributed and Parallel Computing Systems
- Free Radicals and Antioxidants
- Advanced Chemical Physics Studies
- MXene and MAX Phase Materials
- CO2 Reduction Techniques and Catalysts
- Chemistry and Chemical Engineering
- Air Quality Monitoring and Forecasting
- Analytical Chemistry and Chromatography
University of Central Florida
2017-2024
Lawrence Berkeley National Laboratory
2014-2022
University of California, Berkeley
2014-2022
Orange (Poland)
2022
Laboratoire de Chimie Moléculaire et Thioorganique
2022
Bioanalytica (Switzerland)
2022
Robert Bosch (Germany)
2022
National Synchrotron Radiation Research Center
2015
In this paper we report the detection and identification of keto-hydroperoxide (hydroperoxymethyl formate, HPMF, HOOCH2OCHO) other partially oxidized intermediate species arising from low-temperature (540 K) oxidation dimethyl ether (DME). These observations were made possible by coupling a jet-stirred reactor with molecular-beam sampling capabilities, operated near atmospheric pressure, to reflectron time-of-flight mass spectrometer that employs single-photon ionization via tunable...
Significance Highly oxygenated molecules are involved in autooxidation reactions leading to the formation of secondary organic aerosols (SOAs); they also critical intermediates processes for liquid hydrogen degradation and ignition fuels advanced combustion systems. However, these still poorly understood. In this study, we unveil a generalized reaction mechanism involving peroxy radicals with at least three stages sequential O 2 addition. We elucidate important underlying kinetics structural...
This work provides new temperature-dependent mole fractions of elusive intermediates relevant to the low-temperature oxidation dimethyl ether (DME). It extends previous study Moshammer et al. [ J. Phys. Chem. A 2015 , 119 7361 - 7374 ] in which a combination jet-stirred reactor and molecular beam mass spectrometry with single-photon ionization via tunable synchrotron-generated vacuum-ultraviolet radiation was used identify (but not quantify) several highly oxygenated species. Here,...
Significance Furans and related large oxygenated organic carbon species (OC) are highly toxic pollutants. Their integration into soot particles may greatly enhance soot’s hygroscopicity, leading to regional global climate change. We show that furans the primary functional group on formed in hydrocarbon combustion report a reaction scheme elucidates interplay between nonoxygenated hydrocarbons. expect this pathway be important many oxidation systems spanning geosciences, astrophysics, energy...
Hydroxylammonium nitrate (HAN) is a promising candidate to replace highly toxic hydrazine in monopropellant thruster space applications. The reactivity of HAN aerosols on heated copper and iridium targets was investigated using tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry. reaction products were identified by their mass-to-charge ratios ionization energies. Products include NH3, H2O, NO, hydroxylamine (HA), HNO3, small amount NO2 at high temperature. No...
The unusually high heats of vaporization room-temperature ionic liquids (RTILs) complicate the utilization thermal evaporation to study liquid reactivity. Although effusion RTILs into a reaction flow-tube or mass spectrometer is possible, competition between and decomposition RTIL can greatly increase complexity observed products. In order investigate kinetics hypergolic RTIL, 1-butyl-3-methylimidazolium dicyanamide (BMIM+DCA-) was aerosolized reacted with gaseous nitric acid, products were...
Abstract A crucial chain‐branching step in autoignition is the decomposition of ketohydroperoxides (KHP) to form an oxy radical and OH. Other pathways compete with chain‐branching, such as “Korcek” dissociation γ‐KHP a carbonyl acid. Here we characterize formation its formic acid+acetone products from observations n ‐butane oxidation two complementary experiments. In jet‐stirred reactor measurements, KHP observed above 590 K. The concentration decreases increasing temperature, whereas acid...
Uni- and bi-molecular reactions involving Criegee intermediates (CIs) have been the focus of many studies due to role these molecules play in atmospheric chemistry. The reactivity CIs is known strongly depend on their structure. reaction network second simplest CI, acetaldehyde oxide (CH3CHOO), investigated this work an pressure jet-stirred reactor (JSR) during ozonolysis trans-2-butene explore kinetic pathways relevant chemistry low-temperature combustion. mole fraction profiles reactants,...
To develop chemical kinetics models for the combustion of ionic liquid-based monopropellants, identification elementary steps in thermal and catalytic decomposition components such as 2-hydroxyethylhydrazinium nitrate (HEHN) is needed but currently not well understood. The first step protic liquids HEHN typically proton transfer from cation to anion, resulting formation 2-hydroxyethylhydrazine (HEH) HNO3. In part this investigation, high-temperature HEH probed with flash pyrolysis (<1400 K)...
The reaction of unsaturated compounds with ozone (O3) is recognized to lead the formation Criegee intermediates (CIs), which play a key role in controlling atmospheric budget hydroxyl radicals and secondary organic aerosols. network two CIs different functionality, i.e. acetaldehyde oxide (CH3CHOO) glyoxal (CHOCHOO) formed ozone-assisted oxidation crotanaldehyde (CA), investigated over temperature range between 390 K 840 an pressure jet-stirred reactor (JSR) at residence time 1.3 s,...
Abstract The reaction of closed shell Cl 2 molecules with sub-micron droplets composed unsaturated molecules, oleic acid (OA), linoleic (LA), linolenic (LNA), or squalene (Sqe), are investigated in an atmospheric pressure flow tube reactor conjunction a vacuum ultraviolet photoionization aerosol mass spectrometer and scanning mobility particle sizer. is found to react all particles, the reactive uptake coefficients depend on number sites, e.g., γ Cl2 Sqe = (0.66 ± 0.03) × 10 −4 versus OA...
Rational design of novel catalytic materials used to synthesize storable fuels via the CO hydrogenation reaction has recently received considerable attention. In this work, defect poor and rich 2D-MoS2 as well decorated with Mo clusters are employed catalysts for generation acetylene (C2H2) reaction. Temperature programmed desorption is study interaction H2 molecules MoS2 surface formation products. The experiments indicate presence four adsorption sites below room temperature a competitive...
The gas-phase reaction of iodine atoms with hydrocarbon molecules is energetically unfavorable, and there no direct evidence for iodinated product formation by either H abstraction or I addition reactions at ambient temperature. Here we consider the possible heterogeneous submicrometer droplets composed a saturated alkane, squalane (Sq), an unsaturated alkene, squalene (Sqe). investigations are performed in atmospheric pressure photochemical flow tube reactor conjunction vacuum ultraviolet...
Abstract A crucial chain‐branching step in autoignition is the decomposition of ketohydroperoxides (KHP) to form an oxy radical and OH. Other pathways compete with chain‐branching, such as “Korcek” dissociation γ‐KHP a carbonyl acid. Here we characterize formation its formic acid+acetone products from observations n ‐butane oxidation two complementary experiments. In jet‐stirred reactor measurements, KHP observed above 590 K. The concentration decreases increasing temperature, whereas acid...
The reaction of unsaturated compounds with ozone (O
Abstract Biofuels are a promising ecologically viable and renewable alternative to petroleum fuels, with the potential reduce net greenhouse gas emissions. However, biomass sourced fuels often produced as blends of hydrocarbons their oxygenates. Such blending complicates implementation these in combustion applications. Variations biofuel’s composition will dictate properties such auto ignition temperature, reaction delay time, pathways. A handful novel drop-in replacement biofuels for...