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Comprehensive analysis of on-sun catalytic reforming of methane with a hydroxyapatite-supported nickel catalyst in a tubular solar reactor
(2026-07-22)
Chuayboon, Srirat
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Kulporm, Ratikorn
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O-Thong, Sompong
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Pham Minh, Doan
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Abanades, Stéphane
Methane reforming offers a suitable pathway for greenhouse gas utilization, but its implementation is hindered by catalyst deactivation due to carbon deposition and thermal sintering. This study shows that hydroxyapatite serves as a stable catalytic support for solar-driven dry, steam, and dual reforming. The influence of oxidizer type and concentration (H<inf>2</inf>O, CO<inf>2</inf>, H<inf>2</inf>O/CO<inf>2</inf> mixture) is experimentally investigated at 800 °C in a tubular solar reactor. A hydroxyapatite-supported nickel catalyst (Ni/HA) achieves methane conversion exceeding 95% with 95% H<inf>2</inf> and 96% CO selectivity. An excess of oxidant (oxidant/CH<inf>4</inf> mole ratio of 1.2-1.5) is recommended to promote CH<inf>4</inf> conversion, improve solar reactor performance, and prevent carbon formation and catalyst deactivation. Through sequential on-sun experimental runs, energy upgrade factor above 1.5 and solar-to-fuel efficiency over 20% are attained, demonstrating high catalytic performance stabilized by the metal dispersion on the support. Dual reforming exhibits the highest syngas yield and performance, with minimized carbon formation and H<inf>2</inf>/CO ratio approaching 2.0. Catalyst characterization (XRD, FTIR, SEM, TEM/EDX) confirms high thermal/chemical stability of Ni/HA under solar heating conditions. These results demonstrate compatibility of Ni/HA catalyst with solar methane reforming, providing a high-efficiency sustainable system for converting greenhouse gases into syngas.
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Solar Carbo-Thermal and Methano-Thermal Reduction of MgO and ZnO for Metallic Powder and Syngas Production by Green Extractive Metallurgy
(2022-01-01)
Chuayboon, Srirat
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Abanades, Stéphane
The solar carbo-thermal and methano-thermal reduction of both MgO and ZnO were performed in a flexible solar reactor operated at low pressure through both batch and continuous operations. The pyro-metallurgical process is an attractive sustainable pathway to convert and store concentrated solar energy into high-value metal commodities and fuels. Substituting fossil fuel combustion with solar energy when providing high-temperature process heat is a relevant option for green extractive metallurgy. In this study, a thermodynamic equilibrium analysis was first performed to compare the thermochemical reduction of MgO and ZnO with solid carbon or gaseous methane, and to determine the product distribution as a function of the operating conditions. The carbo-thermal and methano-thermal reduction of the MgO and ZnO volatile oxides was then experimentally assessed and compared using a directly irradiated cavity-type solar reactor under different operating conditions, varying the type of carbon-based reducing agent (either solid carbon or methane), temperature (in the range 765–1167◦C for ZnO and 991–1550◦C for MgO), total pressure (including both reduced 0.10–0.15 bar and atmospheric ~0.90 bar pressures), and processing mode (batch and continuous operations). The carbo-thermal and methano-thermal reduction reactions yielded gaseous metal species (Mg and Zn) which were recovered at the reactor outlet as fine and reactive metal powders. Reducing the total pressure favored the conversion of both MgO and ZnO and increased the yields of Mg and Zn. However, a decrease in the total pressure also promoted CO<inf>2</inf> production because of a shortened gas residence time, especially in the case of ZnO reduction, whereas CO<inf>2</inf> formation was negligible in the case of MgO reduction, whatever the conditions. Continuous reactant co-feeding (corresponding to the mixture of metal oxide and carbon or methane) was also performed during the solar reactor operation, revealing an increase in both gas production yields and reaction extent while increasing the reactant feeding rate. The type of carbon reducer influenced the reaction extent, since a higher conversion of both MgO and ZnO was reached when using carbon with a highly available specific surface area for the reactions. The continuous solar process yielded high-purity magnesium and zinc content in the solar-produced metallic powders, thus confirming the reliability, flexibility, and robustness of the solar reactor and demonstrating a promising solar metallurgical process for the clean conversion of both metal oxides and concentrated solar light to value-added chemicals.
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Thermodynamic and experimental investigation of solar-driven biomass pyro-gasification using h2o, co2, or zno oxidants for clean syngas and metallurgical zn production
(2021-04-01)
Chuayboon, Srirat
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Abanades, Stéphane
The solar gasification of biomass represents a promising avenue in which both renewable solar and biomass energy can be utilized in a single process to produce synthesis gas. The type of oxidant plays a key role in solar-driven biomass gasification performance. In this study, solar gasification of beech wood biomass with different oxidants was thermodynamically and experimentally investigated in a 1.5 kW<inf>th</inf> continuously-fed consuming bed solar reactor at 1200◦C under atmospheric pressure. Gaseous (H<inf>2</inf>O and CO<inf>2</inf> ) as well as solid (ZnO) oxidants in pellet and particle shapes were utilized for gasifying beech wood, and the results were compared with pyrolysis (no oxidant). As a result, thermodynamic predictions provided insights into chemical gasification reactions against oxidants, which can support experimental results. Compared to pyrolysis, using oxidants significantly promoted syngas yield and energy upgrade factor. The highest total syngas yield (63.8 mmol/g<inf>biomass</inf> ) was obtained from biomass gasification with H<inf>2</inf>O, followed by CO<inf>2</inf>, ZnO/ biomass mixture (pellets and particles), and pyrolysis. An energy upgrade factor (U) exceeding one was achieved whatever the oxidants, with the maximum U value of 1.09 from biomass gasification with ZnO, thus highlighting successful solar energy storage into chemical products. ZnO/biomass pellets exhibited greater gas yield, particularly CO, thanks to enhanced solid–solid reaction. Solid product characterization revealed that ZnO can be reduced to high-purity Zn through solar gasification, indicating that solar-driven biomass gasification with ZnO is a promising innovative process for CO<inf>2</inf>-free sustainable co-production of metallic Zn and high-quality syngas.
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Insights into the influence of biomass feedstock type, particle size and feeding rate on thermochemical performances of a continuous solar gasification reactor
(2019-01-01)
Chuayboon, Srirat
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Abanades, Stéphane
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Rodat, Sylvain
The solar-driven steam gasification of different lignocellulosic biomass feedstocks was experimentally investigated with a 1.5 kW<inf>th</inf> continuously particle-fed solar reactor at high temperature using real high-flux solar radiation provided by a parabolic dish concentrator. Experiments were carried out with five carbonaceous materials under different biomass feeding rates in the range of 0.8–2.7 g/min at 1300 °C in order to optimize the synthesis gas production and composition. Increasing biomass feeding rate (at constant slightly over-stoichiometric steam/biomass ratio) noticeably promoted the syngas yields that reached up to 83.2 mmol/g<inf>biomass</inf>. The syngas yield (especially H<inf>2</inf>) was more affected by the biomass feedstock (chemical composition) than by the particle size in the considered range (0.3–4 mm). The calorific value of the biomass was solar upgraded up to 24% through the syngas produced with a carbon conversion above 90%, thereby accomplishing efficient solar energy storage into the produced syngas. Increasing the biomass feeding rate inherently shortened the solar processing duration (for a given biomass amount). Thus, the solar energy input and the heat losses were reduced while the overall syngas production capacity was increased, which in turn drastically enhanced both the thermochemical reactor efficiency and the solar-to-fuel energy conversion efficiency with maximum values typically beyond 25%.
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Comprehensive performance assessment of a continuous solar-driven biomass gasifier
(2018-12-15)
Chuayboon, Srirat
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Abanades, Stéphane
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Rodat, Sylvain
The experimental performance assessment of a continuous solar-driven biomass gasifier using real high-flux concentrated solar radiation as the source of process heat has been performed. A comprehensive parametric study considering different lignocellulosic biomass feedstocks (wood type), biomass feeding rates (0.6–2.7 g/min), steam/biomass molar ratios (1.6–2.8), carrier gas flow rates (2–3.3 Nl/min) and reaction temperatures (1100–1300 °C) was conducted for optimizing the syngas production capacity and evaluating the gasification performances. Different wood biomass feedstocks were continuously fed as particles and gasified with H<inf>2</inf>O for producing syngas, thus successfully demonstrating the reliability of the reactor that was operated compatibly with different particle sizes and shapes. A small excess of water with respect to stoichiometry was beneficial for biomass gasification regarding the increase of H<inf>2</inf> and CO and the decrease of CH<inf>4</inf>, CO<inf>2</inf> and C<inf>2</inf>H<inf>m</inf> production. An increase in the gas residence time resulted in the improvement of the syngas yields and quality. Significant enhancement of syngas yields and production rates through the rise of operating temperature was highlighted with activation energy in the range of 24–29 kJ/mol. Increasing biomass feeding rate improved the syngas yields and gasification rates, enabling efficient solar energy storage into syngas and enhancing the energy upgrade factor (U) above 1.20, the solar-to-fuel energy conversion efficiency (η<inf>solar-to-fuel</inf>) above 29% and the thermochemical reactor efficiency (η<inf>reactor</inf>) above 27%.
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Experimental analysis of continuous steam gasification of wood biomass for syngas production in a high-temperature particle-fed solar reactor
(2018-03-01)
Chuayboon, Srirat
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Abanades, Stéphane
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Rodat, Sylvain
Solar steam gasification of beech wood biomass has been performed in a novel high-temperature continuously-fed solar reactor for the thermochemical conversion of low-grade carbonaceous feedstock into transportable and storable gaseous fuels (syngas). The 1.5 kW<inf>th</inf> cavity-type solar reactor was operated in the temperature range of 1100–1300 °C. Large wood biomass particles (3–5 mm size) were continuously fed and gasified with the oxidizing agent to produce syngas, thus demonstrating the reactor suitability for large particle size processing. Operating parameters were varied in order to optimize the syngas production. The effect of steam flow-rate, carrier gas flow-rate, temperature, and biomass feeding rate on the syngas yield and reactor performances was experimentally investigated. The increase of steam flow-rate favored H<inf>2</inf>, CO<inf>2</inf> and CH<inf>4</inf> and reduced CO production. A noteworthy increase of the syngas yield with the temperature was highlighted, while the increase of carrier gas flow-rate was detrimental to the amount of syngas produced because of lowered gas residence time. The increase of biomass feeding rate (in the range of 0.8–1.8 g/min) showed noteworthy impact on the syngas composition without affecting the reactor performance, yielding high-quality syngas with a carbon conversion rate above 80%, while the total syngas yield was stable at about 70 mmol/g<inf>biomass</inf>.

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