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Comparative CFD modeling of foam and conventional pellet catalysts in glycerol steam reforming
(2025-07-15)
Simasatitkul, Lida
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Phitchayakorn, Chattharika
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Amornraksa, Suksun
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Anantpinijwatna, Amata
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Assabumrungrat, Suttichai
A novel approach to glycerol valorization via steam reforming was investigated through computational fluid dynamics (CFD) modelling. The performance characteristics of conventional pellet catalysts were compared with foam catalysts in a 6-inch diameter packed bed reactor. A two-dimensional pseudo-homogeneous steady-state model was employed to evaluate catalyst configurations ranging from 10 to 30 pores per inch (PPI). The foam catalyst structures exhibited superior performance across key metrics, achieving maximum hydrogen yield (60 %) at one-third of the reactor length whilst reducing pressure drop by 95 % compared to conventional pellets. Within the foam configurations, the 10PPI variant demonstrated optimal performance characteristics, with an 80 % reduction in normalized pressure drop compared to 30PPI, whilst maintaining comparable product yields. The enhanced performance was attributed to the open-cell architecture, which facilitated improved mass transfer and reduced diffusion limitations. These findings suggest that foam catalysts represent a promising alternative to conventional pellet configurations for glycerol steam reforming processes.
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Compact heat integrated reactor system of steam reformer, shift reactor and combustor for hydrogen production from ethanol
(2020-06-01)
Khaodee, Watcharapong
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Jiwanuruk, Tara
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Ountaksinkul, Khunnawat
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Charojrochkul, Sumittra
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Charoensuk, Jarruwat
A compact heat integrated reactor system (CHIRS) of a steam reformer, a water gas shift reactor, and a combustor were designed for stationary hydrogen production from ethanol. Different reactor integration concepts were firstly studied using Aspen Plus. The sequential steam reformer and shift reactor (SRSR) was considered as a conventional system. The efficiency of the SRSR could be improved by more than 12% by splitting water addition to the shift reactor (SRSR-WS). Two compact heat integrated reactor systems (CHIRS) were proposed and simulated by using COMSOL Multiphysics software. Although the overall efficiency of the CHIRS was quite a bit lower than the SRSR-WS, the compact systems were properly designed for portable use. CHIRS (I) design, combining the reactors in a radial direction, was large in reactor volume and provided poor temperature control. As a result, the ethanol steam reforming and water gas shift reactions were suppressed, leading to lower hydrogen selectivity. On the other hand, CHIRS (II) design, combining the process in a vertical direction, provided better temperature control. The reactions performed efficiently, resulting in higher hydrogen selectivity. Therefore, the high performance CHIRS (II) design is recommended as a suitable stationary system for hydrogen production from ethanol.
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Optimization of hydrogen production from three reforming approaches of glycerol via using supercritical water with in situ CO2 separation
(2019-01-22)
Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Arpornwichanop, Amornchai
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Assabumrungrat, Suttichai
A pathway for hydrogen production from supercritical water reforming of glycerol integrated with in situ CO<inf>2</inf> removal was proposed and analyzed. The thermodynamic analysis carried out by the minimizing Gibbs free energy method of three glycerol reforming processes for hydrogen production was investigated in terms of equilibrium compositions and energy consumption using AspenPlus™ simulator. The effect of operating condition, i.e., temperature, pressure, steam to glycerol (S/G) ratio, calcium oxide to glycerol (CaO/G) ratio, air to glycerol (A/G) ratio, and nickel oxide to glycerol (NiO/G) ratio on the hydrogen production was investigated. The optimum operating conditions under maximum H<inf>2</inf> production were predicted at 450 °C (only steam reforming), 400 °C (for autothermal reforming and chemical looping reforming), 240 atm, S/G ratio of 40, CaO/G ratio of 2.5, A/G ratio of 1 (for autothermal reforming), and NiO/G ratio of 1 (for chemical looping reforming). Compared to three reforming processes, the steam reforming obtained the highest hydrogen purity and yield. Moreover, it was found that only autothermal reforming and chemical looping reforming were possible to operate under the thermal self-sufficient condition, which the hydrogen purity of chemical looping reforming (92.14%) was higher than that of autothermal reforming (52.98%). Under both the maximum H<inf>2</inf> production and thermal self-sufficient conditions, the amount of CO was found below 50 ppm for all reforming processes.
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Catalytic reforming of glycerol in supercritical water with nickel-based catalysts
(2014-09-12)
Pairojpiriyakul, Thirasak
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Croiset, Eric
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Kiatkittipong, Kunlanan
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Kiatkittipong, Worapon
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Arpornwichanop, Amornchai
The catalytic performance of nickel catalysts supported on La <inf>2</inf>O<inf>3</inf>, α-Al<inf>2</inf>O<inf>3</inf>, γ-Al <inf>2</inf>O<inf>3</inf>, ZrO<inf>2</inf>, and YSZ for supercritical water reforming of glycerol was investigated. Experiments were conducted in a tubular reactor made of Inconel-625 with the temperature range of 723-848 K under a pressure of 25 MPa. Carbon formation causing operation failure was observed for α-Al<inf>2</inf>O<inf>3</inf>, γ-Al<inf>2</inf>O<inf>3</inf> and ZrO<inf>2</inf> at temperatures higher than 748, 798 and 823 K, respectively. Ni/La<inf>2</inf>O<inf>3</inf> exhibited the highest H<inf>2</inf> yield where almost complete conversion was obtained at 798 K. Moderate space velocities (WHSV = 6.45 h<sup>-1</sup>) and glycerol feed concentration (5wt.%) favor high hydrogen selectivity and yield. Methanation is favored at a low WHSV or high glycerol feed concentration, resulting in a lower H<inf>2</inf> yield. Increasing Ni loading on the Ni/La<inf>2</inf>O<inf>3</inf> catalyst strongly promoted the reforming, water-gas shift, and methanation reactions, which contributed significantly to the product species distribution. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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Integration of ethanol processor and CO2 absorption to produce hydrogen for fuel cell
(2014-01-01)
Patcharavorachot, Yaneeporn
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Sangduan, Kidakarn
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Ponpesh, Pimporn
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Assabumrungrat, Suttichai
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Arpornwichanop, Amornchai
Ethanol is considered to be a promising candidate for hydrogen source. Hydrogen-rich gas with less impurity level of carbon monoxide and carbon dioxide is required for fuel cell applications. In a conventional ethanol processor, CO can be removed by water gas-shift reactors, followed by a preferential oxidation unit. Since a high content of CO<inf>2</inf> may degrade the efficiency of fuel cell systems, the removal of CO<inf>2</inf> should be included in the ethanol processor to separate CO<inf>2</inf> from the synthesis gas. In this study, the thermodynamic analysis of hydrogen production from the integration of ethanol reforming process and CO<inf>2</inf> absorption unit is performed. The purity of H2, efficiency of CO<inf>2</inf> removal and heat consumption are key factors to be analyzed with regard to different key parameters. The result indicates that the H2 purity of 97 mol.% can be reached when the CO<inf>2</inf> absorption unit is included in the ethanol steam reforming. In addition, it is found that the CO<inf>2</inf> removal can be improved with increases of amine concentration, number of absorber and stripper stages, whereas increase of inlet gas temperature show the opposite trend. However, high energy demand is unavoidable when a number of absorber and stripper stages increase.
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Hydrogen production from catalytic supercritical water reforming of glycerol with cobalt-based catalysts
(2013-04-15)
Pairojpiriyakul, Thirasak
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Croiset, Eric
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Kiatkittipong, Worapon
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Kiatkittipong, Kunlanan
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Arpornwichanop, Amornchai
Glycerol reforming under catalytic supercritical water at temperatures in the range of 723-848 K using Co catalyst deposited on various supports including ZrO<inf>2</inf>, yttria-stabilized zirconia (YSZ), La<inf>2</inf>O<inf>3</inf>, γ-Al<inf>2</inf>O<inf>3</inf>, and α-Al<inf>2</inf>O<inf>3</inf> was investigated. An increase in operating temperature promoted the continued increase in glycerol conversion; however, carbon formation causing system operation failure was observed for γ-Al<inf>2</inf>O<inf>3</inf> and α-Al<inf>2</inf>O<inf>3</inf> at high operating temperatures (i.e. 748-798 K). Co supported on YSZ provided the most efficient performance for hydrogen production. 10 wt.% Co loading on YSZ support was an optimum amount to enhance the reaction. The increase in glycerol conversion and reduction of the amount of liquid products were observed for lower weight hourly space velocity (WHSV), higher operating temperature or higher cobalt loading. On Co/YSZ catalyst, glycerol conversion of 0.94 and hydrogen yield of 3.72 was obtained with WHSV of 6.45 h<sup>-1</sup>at 773 K. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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