Allen Arturo Puente Urbina


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Puente Urbina

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Allen Arturo

ORCID

0000-0001-5328-2142

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Publications 1 - 7 of 7
  • Understanding Fast Pyrolysis of Lignin to Produce Chemicals and Fuels
    Item type: Doctoral Thesis
    Puente Urbina, Allen Arturo (2022)
  • Identifying Opportunities to Promote Systems Thinking in Catalysis Education
    Item type: Journal Article
    Ravi, Manoj; Puente Urbina, Allen Arturo; van Bokhoven, Jeroen A. (2021)
    Journal of Chemical Education
    While several engineering and science disciplines, including biology and environmental science, have greatly benefited from adopting a systems thinking approach, its extension to chemistry education is a much more recent advancement. The initial body of literature in this direction has largely surveyed the feasibility for systems thinking in general chemistry courses. Herein, we go a step further to explore the possibilities that systems thinking present for the instruction of more advanced chemistry courses, specifically in the context of catalysis education. Since catalysis has conventionally been taught employing a reductionist perspective, we identify the opportunities and challenges for instructors in transitioning to a systems thinking teaching style. We build our analysis in accordance with the principle of constructive alignment, where we systematically address the implications for systems thinking in writing intended learning outcomes, designing learning activities, and formulating student assessments. Through a series of carefully crafted examples in homogeneous as well as heterogeneous catalysis, we illustrate how embracing systems thinking can potentially enable a paradigm shift in catalysis education.
  • Tuning the zeolite acidity enables selectivity control by suppressing ketene formation in lignin catalytic pyrolysis
    Item type: Journal Article
    Pan, Zeyou; Puente Urbina, Allen Arturo; Batool, Syeda R.; et al. (2023)
    Nature Communications
    Unveiling catalytic mechanisms at a molecular level aids rational catalyst design and selectivity control for process optimization. In this study, we find that the Brønsted acid site density of the zeolite catalyst efficiently controls the guaiacol catalytic pyrolysis mechanism. Guaiacol demethylation to catechol initiates the reaction, as evidenced by the detected methyl radicals. The mechanism branches to form either fulvenone (c-C5H4 = C = O), a reactive ketene intermediate, by catechol dehydration, or phenol by acid-catalyzed dehydroxylation. At high Brønsted acid site density, fulvenone formation is inhibited due to surface coordination configuration of its precursor, catechol. By quantifying reactive intermediates and products utilizing operando photoelectron photoion coincidence spectroscopy, we find evidence that ketene suppression is responsible for the fivefold phenol selectivity increase. Complementary fulvenone reaction pathway calculations, along with 29Si NMR-MAS spectroscopy results corroborate the mechanism. The proposed, flexible operando approach is applicable to a broad variety of heterogeneous catalytic reactions.
  • Optimization of Lignin Extraction from Pine Wood for Fast Pyrolysis by Using γ-valerolactone-Based Binary Solvent System
    Item type: Journal Article
    Jampa, Sureerat; Puente Urbina, Allen Arturo; Ma, Zhiqiang; et al. (2019)
    ACS Sustainable Chemistry & Engineering
  • Technology overview of fast pyrolysis of lignin: current state and potential for scale‐up
    Item type: Journal Article
    Singh-Morgan, Amrita; Puente Urbina, Allen Arturo; van Bokhoven, Jeroen A. (2022)
    ChemSusChem
    Lignin is an abundant natural polymer obtained from lignocellulosic biomass and rich in aromatic substructures. When efficiently depolymerized, it has great potential in the production of value-added chemicals. Fast pyrolysis is a promising depolymerization method, but current studies focus mainly on small quantities of lignin. To determine the potential for upscaling, we evaluated the systems used in the most relevant unit operations of fast pyrolysis of lignin. Fluidized-bed reactors have the most potential. It would be beneficial to combine them with the following: slug injectors for feeding, hot particle filters, cyclones, and fractional condensation for product separation and recovery. Moreover, upgrading lignin pyrolysis oil would allow reaching the necessary quality parameters for particular applications.
  • Isomer-dependent catalytic pyrolysis mechanism of the lignin model compounds catechol, resorcinol and hydroquinone
    Item type: Journal Article
    Pan, Zeyou; Puente Urbina, Allen Arturo; Bodi, Andras; et al. (2021)
    Chemical Science
    The catalytic pyrolysis mechanism of the initial lignin depolymerization products will help us develop biomass valorization strategies. How does isomerism influence reactivity, product formation, selectivities, and side reactions? By using imaging photoelectron photoion coincidence (iPEPICO) spectroscopy with synchrotron radiation, we reveal initial, short-lived reactive intermediates driving benzenediol catalytic pyrolysis over H-ZSM-5 catalyst. The detailed reaction mechanism unveils new pathways leading to the most important products and intermediates. Thanks to the two vicinal hydroxyl groups, catechol (o-benzenediol) is readily dehydrated to form fulvenone, a reactive ketene intermediate, and exhibits the highest reactivity. Fulvenone is hydrogenated on the catalyst surface to phenol or is decarbonylated to produce cyclopentadiene. Hydroquinone (p-benzenediol) mostly dehydrogenates to produce p-benzoquinone. Resorcinol, m-benzenediol, is the most stable isomer, because dehydration and dehydrogenation both involve biradicals owing to the meta position of the hydroxyl groups and are unfavorable. The three isomers may also interconvert in a minor reaction channel, which yields small amounts of cyclopentadiene and phenol via dehydroxylation and decarbonylation. We propose a generalized reaction mechanism for benzenediols in lignin catalytic pyrolysis and provide detailed mechanistic insights on how isomerism influences conversion and product formation. The mechanism accounts for processes ranging from decomposition reactions to molecular growth by initial polycyclic aromatic hydrocarbon (PAH) formation steps to yield, e.g., naphthalene. The latter involves a Diels–Alder dimerization of cyclopentadiene, isomerization, and dehydrogenation.
  • Direct Evidence on the Mechanism of Methane Conversion under Non‐oxidative Conditions over Iron‐modified Silica: The Role of Propargyl Radicals Unveiled
    Item type: Other Journal Item
    Puente Urbina, Allen Arturo; Pan, Zeyou; Paunović, Vladimir; et al. (2021)
    Angewandte Chemie. International Edition
    Radical-mediated gas-phase reactions play an important role in the conversion of methane under non-oxidative conditions into olefins and aromatics over iron-modified silica catalysts. Herein, we used operando photoelectron photoion coincidence spectroscopy to disentangle the elusive C2+ radical intermediates participating in the complex reaction network. Our experiments pinpointed different C2-C5 radical species that allow for a stepwise growth of the hydrocarbon chains. Herein, propargyl radicals (H2C-C≡C-H) are identified as essential precursors for the formation of aromatics, which contribute with the formation of heavier hydrocarbon products via hydrogen abstraction - acetylene addition routes (HACA mechanism). These results provide comprehensive mechanistic insights that are relevant for development of methane valorization processes.
Publications 1 - 7 of 7