Seyyed Meysam Khatoonabadi


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Khatoonabadi

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Seyyed Meysam

ORCID

0000-0003-1978-5832

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2023 - 20242
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Publications 1 - 2 of 2
  • High-pressure kinetic interactions between CO and H₂ during syngas catalytic combustion on PdO
    Item type: Journal Article
    Sui, Ran; Mantzaras, John; Bombach, Rolf; et al. (2023)
    Proceedings of the Combustion Institute
    The catalytic combustion of H2/CO/O2/N2 mixtures over PdO was investigated at pressures 3 to 10 bar, H2:CO volumetric ratios 1:5 to 3:1, and global equivalence ratios φ = 0.13 and 0.23. The catalyst surface temperatures were controlled to 540–690 K, a range especially important for hybrid hetero-/homogeneous combustion approaches with large gas turbines at idle or part-load operation and for microreactors with recuperative small-scale turbines. In situ Raman measurements determined the major gas-phase species concentrations over the catalyst boundary layers in a channel-flow reactor, thermocouples monitored the surface temperatures, and surface characterization identified the catalyst oxidation state (PdO) and surface morphology. A 2-D CFD code with a detailed catalytic reaction mechanism simulated the experiments. Simulations and measurements of the combustion of the individual fuel components revealed pressure dependencies ∼p0.74 and ∼p0.10 for the CO and H2 reactivities, respectively, at the investigated equivalence ratios. In the combustion of H2/CO blends, transition temperatures (TTRAN) were identified, below (above) which H2 inhibited (promoted) chemically the oxidation of CO. The transition temperatures decreased with increasing H2:CO volumetric ratio, pressure, and equivalence ratio. Sensitivity analysis indicated that the H2 and O2 adsorption reactions had the larger inhibiting effect on CO oxidation, particularly at lower pressures. Comparisons with other noble metals showed that the PdO transition temperatures were higher than those on Pt and Rh. Even though this behavior favored Pt and Rh for the ignition of syngas in practical catalytic burners, the H2 and CO kinetic coupling (H2 inhibition) was considerably weaker on PdO at T < TTRAN, thus rendering PdO also potentially suitable for low temperature syngas ignition.
  • A pore-level 3D lattice Boltzmann simulation of mass transport and reaction in catalytic particles used for methane synthesis
    Item type: Journal Article
    Khatoonabadi, Seyyed Meysam; Prasianakis, Nikolaos I.; Mantzaras, John (2024)
    International Journal of Heat and Mass Transfer
    Three-dimensional lattice Boltzmann (LB) simulations were carried out to investigate the mass transport and reaction inside and around catalytic porous particles used in fluidized beds for the synthesis of methane from biogas (H2/CO mixtures). The 3D internal porous structure of a real particle with a size ∼200 μm was assessed with Synchrotron-based X-ray tomography (XTM). Pore-resolved simulations with a suitable LB model for catalytic reactions in microflows revealed that the preferential diffusion of H2 and the resulting inability of CO to penetrate deep inside the pores led to segregated distributions of the two species, hindering reaction in the downstream parts of the particle and rendering CO the deficient reactant. The implications for practical fluidized beds are that, for specific bed zones with a high dense-phase (solid-phase) volume fraction and a predominant flow direction, CO starvation may occur and may thus limit the methane yields. Subsequent parametric studies of spherical particles with a diameter 2R=150 μm and an artificially generated porosity allowed comparisons of LB results with radially symmetric analytical continuum-model solutions. The LB simulations revealed appreciable angular variations in the CO concentration at the external surface (r=R) and the outer layers of particle, especially at the higher investigated Damköhler numbers, which were however diminished as the core of the particle (r→0) was approached. The large angular variations, in conjunction with the skewed CO distributions towards their lower values, led to LB-computed particle effectiveness factors ∼30% lower than the corresponding analytical solutions.
Publications 1 - 2 of 2