Online Analysis of Biomass Pyrolysis Tar by Photoionization Mass Spectrometry

Jia, Liangyuan; Brech, Yann Le; Mauviel, Guillain; Qi, Fei; Frowein, Matthias Bente-von; Ehlert, Sven; Zimmermann, Ralf; Dufour, Anthony

doi:10.1021/acs.energyfuels.5b02274

Cited by 59 publications

(61 citation statements)

References 52 publications

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“…The present study focuses on the reaction of pyrolysis and oxidation of guaiacol, or o-methoxy phenol, which is more representative of lignin pattern and is found in large amounts in tars produced from lignin 5,7,[14][15][16][17][18][19] . This compound is furthermore the most often selected surrogate of lignin primary tars in the literature 18,[20][21][22][23] .…”

Section: Introductionmentioning

confidence: 99%

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

et al. 2018

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Guaiacol or 2-methoxy phenol is one of the main primary tars produced during lignin pyrolysis. Tar conversion in the gas phase influences the production of gaseous and condensable products, and is also responsible for PAH and soot formation during biomass and bio-oil gasification or combustion. Guaiacol pyrolysis and oxidation under stoichiometric conditions were studied in a jet stirred reactor between 623 and 923 K for a residence time of 2 s and under a pressure of 800 Torr (106.7 kPa). Speciation was obtained thanks to online gas chromatography using flame ionization detection and mass spectrometry and allowed the quantification of 22 species in pyrolysis and 42 species in oxidation. Decomposition of guaiacol starts at 650 K, and a conversion degree of 50% is obtained at about 785 K in pyrolysis and 765 K in oxidation. The main products of reaction are pyrocatechol o-HOCHOH, o-hydroxybenzaldehyde, methylcatechols, and light products, such as methane, carbon monoxide, ethylene, and hydrogen. A detailed kinetic model based on a combustion model for light aromatics and anisole has been extended to guaiacol. Thermochemical data of guaiacol and main products were calculated theoretically at the CBS-QB3 level of theory. The model predicts well the conversion of guaiacol and the formation of the main products. Guaiacol decomposes mainly through a unimolecular O-C bond breaking to hydroxy phenoxy and methyl radicals in both pyrolysis and oxidation, but H atom abstractions are also of importance in the low temperature range of the study. The unimolecular mechanism leads mainly to pyrocatechol and methylcatechols, whereas the chain radical mechanism is responsible for the formation of hydroxybenzaldehyde. As for anisole but in a much lower extent, an early formation of benzene and soot precursors is observed.

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Section: Introductionmentioning

confidence: 99%

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

et al. 2018

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“…REMPI, which utilizes intense ultraviolet (UV) light laser pulses for two photon absorption process, is highly selective and sensitive toward specific vibronic structure compounds such as aromatic compounds. 17 Unlike REMPI processes, SPI uses vacuum ultraviolet (VUV) where a single photon of sufficient energy is absorbed by a molecule leading to a positively charged ion. Thus, SPI with VUV is capable of soft ionization of wide array of organic compounds, including saturated hydrocarbons whose ionization energies are just below the energy of the applied VUV photon.…”

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confidence: 99%

Molecular Characterization of Volatiles and Petrochemical Base Oils by Photo-Ionization GC×GC-TOF-MS

et al. 2017

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The characterization of organic mixtures by comprehensive two-dimensional gas chromatography (GC×GC) coupled to electron impact (EI) ionization time-of-flight mass spectrometry (TOF-MS) allows the detection of thousands of compounds. However, owing to the exhaustive fragmentation following EI ionization, despite the use of mass spectral libraries, a majority of the compounds remains unidentified because of the lack of parent ion preservation. Thus, soft-ionization energies leading to organic compounds being ionized with limited or no fragmentation, retaining the molecular ion, has been of interest for many years. In this study, photoionization (PI) was evaluated as the ion source for GC×GC-TOF-MS measurements. First, capabilities and limitations of PI were tested using an authentic mixture of compounds of several chemical classes. Ionization energy exhibited by PI, equivalent to 10.8 eV, resulted in significant retention of molecular ion information; [M] for alkanes, ketones, FAMEs, aromatics, [M-H] for chloroalkanes, and [M-HO] for alcohols. Second, considering the potential of PI for hydrocarbons, base oils, complex mixtures of saturated and unsaturated hydrocarbons blended for finished lubricant formulations, were extensively evaluated. Several chemical classes of hydrocarbons were positively identified including a large number of isomeric compounds, both aliphatics and cyclics. Interestingly, branched-alkanes were ionized with lower excess internal energy, not only retaining the molecular ions but also exhibiting unique fragmentation patterns. The results presented herein offer a unique perspective into the detailed molecular characterization of base oils. Such unprecedented identification power of PI coupled with GC×GC-TOF-MS is the first report covering volatiles to low-volatile organic mixtures.

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“…86 The authors concluded that, compared to hemicellulose, lignin particles require an increased reaction time for complete pyrolysis in industrial processes. In their follow-up studies with similar instrumentation, deoxygenation reactions yielding polycyclic aromatic hydrocarbons (PAHs) were also identified, 87,88 and the authors review different ionization light sources utilizing REMPI laser schemes, VUV lamps, synchrotron radiation, and higher harmonic generation.…”

Section: Mechanistic Insights Into Sustainable Fuel Productionmentioning

confidence: 99%

Photoelectron Photoion Coincidence Spectroscopy Provides Mechanistic Insights in Fuel Synthesis and Conversion

et al. 2021

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Clean combustion, i.e., the reduction of NOx and soot emissions, and carbon neutrality, achieved in part by biofuel synthesis, are major milestones in the transition to a sustainable future. To overcome empiric and time-consuming process optimization steps, we need detailed reaction mechanistic and chemical insights on these processes. Be it in combustion or in catalysis, highly reactive intermediates, such as radicals, carbenes, and ketenes drive chemical reactions. Knowing the fate of these species helps develop strategies to optimize chemical energy conversion processes. This calls for advanced mass spectrometric tools, which enable the detection of transient species. In this review, we report on the application of state-of-the-art photoelectron photoion coincidence (PEPICO) spectroscopy with vacuum ultraviolet (VUV) synchrotron radiation as advanced diagnostic tools in catalysis and combustion research. We discuss reaction mechanisms in biomass conversion to sustainable fuels, where we report on the pyrolysis of wood samples probed using VUV photoionization mass spectrometry (PIMS) and obtain deep mechanistic insights in the (non)catalytic pyrolysis of lignin model compounds with PEPICO detection. PEPICO is also shown to contribute to the mechanistic understanding of catalysis by unveiling catalytic alkane valorization mechanisms. We discuss how PEPICO detection advances combustion diagnostics, thanks to the application of photoelectron spectroscopy and velocity map imaging. We report on mechanistic aspects of ignition, such as fuel radical formation and oxidation to peroxy species, and discuss reaction pathways of pollutant formation. In addition, we zoom into the elementary reactions of combustion and discuss isomer-selective kinetics experiments on radical oxidation. Newly revealed reaction pathways to polycyclic aromatic hydrocarbon (PAH) formation are also detailed. Finally, we describe current instrumental developments to improve PEPICO detection and report on innovative sources, reactors, and reaction sampling approaches to be combined with this technique.

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Online Analysis of Biomass Pyrolysis Tar by Photoionization Mass Spectrometry

Cited by 59 publications

References 52 publications

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

Molecular Characterization of Volatiles and Petrochemical Base Oils by Photo-Ionization GC×GC-TOF-MS

Photoelectron Photoion Coincidence Spectroscopy Provides Mechanistic Insights in Fuel Synthesis and Conversion

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