INAMAT2 - Institute for Advanced Materials and Mathematics

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Browsing INAMAT2 - Institute for Advanced Materials and Mathematics by Author "Ábrego, Javier"

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    PublicationOpen Access
    Exploring a low-cost valorization route for amazonian cocoa pod husks through thermochemical and catalytic upgrading of pyrolysis vapors
    (American Chemical Society, 2023) Villasana, Yanet; Armenise, Sabino; Ábrego, Javier; Hablich, Karina; Bimbela Serrano, Fernando; Cornejo Ibergallartu, Alfonso; Gandía Pascual, Luis; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
    Ecuador as an international leader in the production of cocoa beans produced more than 300 000 tons in 2021; hence, the management and valorization of the 2 MM tons of waste generated annually by this industry have a strategic and socioeconomic value. Consequently, appropriate technologies to avoid environmental problems and promote sustainable development and the bioeconomy, especially considering that this is a megadiverse country, are of the utmost relevance. For this reason, we explored a low-cost pyrolysis route for valorizing cocoa pod husks from Ecuador’s Amazonian region, aiming at producing pyrolysis liquids (bio-oil), biochar, and gas as an alternative chemical source from cocoa residues in the absence of hydrogen. Downstream catalytic processing of hot pyrolysis vapors using Mo- and/or Ni-based catalysts and standalone γ-Al2O3 was applied for obtaining upgraded bio-oils in a laboratory-scale fixed bed reactor, at 500 °C in a N2 atmosphere. As a result, bimetallic catalysts increased the bio-oil aqueous phase yield by 6.6%, at the expense of the organic phase due to cracking reactions according to nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS) results. Overall product yield remained constant, in comparison to pyrolysis without any downstream catalytic treatment (bio-oil ∼39.0–40.0 wt % and permanent gases 24.6–26.6 wt %). Ex situ reduced and passivated MoNi/γ-Al2O3 led to the lowest organic phase and highest aqueous phase yields. The product distribution between the two liquid phases was also modified by the catalytic upgrading experiments carried out, according to heteronuclear single-quantum correlation (HSQC), total correlation spectroscopy (TOCSY), and NMR analyses. The detailed composition distribution reported here shows the chemical production potential of this residue and serves as a starting point for subsequent valorizing technologies and/or processes in the food and nonfood industry beneficiating society, environment, economy, and research.
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    PublicationOpen Access
    Low temperature chemical looping combustion of pyrolysis gases in a fixed bed reactor
    (Elsevier, 2025-08-01) Gracia Monforte, César; Maldonado-Martín, Francisco; Atienza Martínez, María; Ábrego, Javier; Ciencias; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
    This study presents an experimental investigation into the feasibility of oxidizing biomass pyrolysis gases at relatively low temperatures using a chemical looping combustion (CLC) approach. The application of this alternative method would enable the capture of carbon from the pyrolysis gas stream, which is currently released into the atmosphere in most pyrolysis systems, as high-purity CO2. In a fixed bed reactor, the reduction behavior of three different Cu-based oxygen carriers (OC) - pure CuO pellets, carulite and Al2O3-supported CuO - was evaluated to determine whether pyrolysis gases could be completely oxidized to CO2 and H2O within a temperature range of 600–650 ◦C and at weight hourly space velocities (WHSV) of 0.06–0.10 h− 1 . Both CuO and carulite exhibited significant amounts of unconverted pyrolysis gases even during the initial stages of the reduction experiments. In contrast, Al2O3-supported CuO emerged as the most effective material, facilitating the complete oxidation of pyrolysis gases over extended reaction times. For this oxygen carrier, a decline in the combustion efficiency was only observed at very high (90 %) reduction conversions. Reduction/oxidation cycles for this most promising material were successfully demonstrated, with the oxygen carrier showing no signs of activity loss after 10 cycles. However, carbon deposition was detected under several experimental conditions, which could potentially reduce the carbon capture efficiency of the process.