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Bifunctional WOx/SiO2 catalysts for hydrogen-free upgrading of B100 and bio-ethylene to SAF and green diesel precursors via olefin metathesis and deoxygenation
(2026-09-15)
Solehudin, Mochamad
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Wengwirat, Kanokwan
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Promchana, Pratya
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Poo-arporn, Yingyot
;
Limphirat, Wanwisa
This work presents a hydrogen-free catalytic route for upgrading palm-derived biodiesel (B100) into olefinic precursors for sustainable aviation fuel (SAF) and green diesel (GD) using bifunctional WO<inf>x</inf>/SiO<inf>2</inf> catalysts under atmospheric pressure. The catalysts integrate olefin cross-metathesis, mediated by surface W CH<inf>2</inf> species, with deoxygenation via Lewis-acidic W O sites, enabling selective C C bond exchange and C O bond cleavage without external hydrogen or noble metals. Detailed mechanistic studies revealed that methyl oleate (MO) rapidly undergoes cross-metathesis with ethylene to yield SAF-range C<inf>9</inf>–C<inf>14</inf> precursors, while methyl palmitate (MP) contributes primarily to GD (C<inf>15</inf>–C<inf>18</inf>) through ketene intermediates and decarbonylation–hydrogen transfer pathways. Contact time and temperature experiments confirmed that MO conversion is kinetically favored at milder conditions, whereas MP-derived pathways dominate at higher temperatures and extended residence times. Catalyst loading studies show that the 3 and 5 wt% WO<inf>x</inf>/SiO<inf>2</inf> catalysts are dominated by highly dispersed isolated and polymeric WO<inf>x</inf> species, which exhibit higher accessible acidity and consequently promote secondary cracking reactions. In contrast, the 8 wt% WO<inf>x</inf>/SiO<inf>2</inf> catalyst contains a higher fraction of bulk crystalline WO<inf>3</inf> domains, resulting in reduced surface acidity and suppressed cracking. Overall, 8 wt% WO<inf>x</inf>/SiO<inf>2</inf> delivers reasonable rates with high selectivity toward SAF/GD precursors, while minimizing secondary cracking. It can be regenerated and recycled with substantial recovery of catalytic performance, establishing a robust, low-pressure, and hydrogen-free pathway for scalable renewable fuel production from B100.
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Hydrogen-Free Production of Green Diesel from Deoxygenation of Methyl Palmitate via Cross-Metathesis with Bio-Ethylene Using Supported WO3 Catalyst
(2025-06-02)
Solehudin, Mochamad
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Wengwirat, Kanokwan
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Promchana, Pratya
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Poo-arporn, Yingyot
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Limphirat, Wanwisa
Traditional green diesel production from used cooking oils faces challenges in H<inf>2</inf> supply and carbon loss as CO<inf>2</inf>. This study presents a novel hydrogen-free deoxygenation process via cross-metathesis between fatty acids/FAMEs and bio-ethylene under atmospheric pressure as an alternative sustainable solution. The carboxyl end group was removed as CO and blue hydrogen, bearing the hydrocarbons as green diesel, sustainable aviation fuel (SAF), and bio-naphtha. Bifunctional WO<inf>3</inf>/SiO<inf>2</inf> was prepared and characterized by XRD, XANES, EXAFS, DR-UV, and Raman. Lewis site (W = O) promotes the formation of ketene intermediate that undergoes cross-metathesis with ethylene over tungsten carbene (WCH<inf>2</inf>) sites, yielding a C16-ene majority with trace amounts of C17-ene. Smaller hydrocarbons (<C15) are obtained as minor components from decarbonylation, hydrogen transfer, and cracking. The increased contact time (27–106 g h/mol) at 460 °C results in increased conversion (30%–87 %), green diesel (12%–57%), SAF (3.5%–12.7%), and bio-naphtha (1.3%–5.3%). Optimal green diesel production of 2.92 h⁻¹ with 73% selectivity can be achieved at 480 °C. SAF and bio-naphtha yields can be tuned by varying temperature from 460 to 500 °C. This provides a sustainable pathway for renewable liquid fuels without an external hydrogen supply.
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Economic and environmental analyses for achieving net-zero CO2 emissions of a green diesel production process
(2024-12-01)
Pongboriboon, Nattapat
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Mariyappan, Vinitha
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Wu, Wei
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Chandra-Ambhorn, Walairat
Background: In this study, palm oil hydrotreating for producing green diesel has been thoroughly explored, emphasizing high yields, reduced environmental impact, and lower energy consumption, particularly with solar collectors. Methods: This study addresses these gaps by evaluating impacts on multiple fronts, including carbon revenue, GHG emissions, and overall environmental effects. The Life Cycle Assessment (LCA) technique, utilizing the CML method developed by Centrum voor Milieukunde Leiden (the Center for Environmental Science at Leiden University, The Netherlands) in SimaPro®, is employed to assess the environmental impact of green diesel production processes. The CML method evaluates environmental impacts through three phases: characterization, which quantifies environmental loads; midpoint, which assesses intermediate impact stages such as global warming potential; and damage, which evaluates potential harm to human health, ecosystems, and resource availability. The scope of work includes simulating the production process and incorporating a CO<inf>2</inf> capture unit with Aspen Plus®. Additionally, kinetic parameters for the palm oil hydrotreating reaction were validated, and energy consumption was optimized using the Aspen Energy Analyzer. Significant findings: The net-zero emissions of the green diesel (GD) production from crude palm oil (CPO) is achieved by using an integration of an evacuated tube solar collector (ETSC), heat exchanger network, and a post-separation CO<inf>2</inf> capture process. Through the life cycle assessment (LCA), the terrestrial ecotoxicity potential (TEIP) is identified as a significant environmental factor due to chemical pesticides used in the oil palm cultivation. The carbon neutrality is validated by producing 1 kg of GD from CPO down to 0.0617 kg total CO<inf>2</inf> emissions since the net CO<inf>2</inf> sequestration for palm oil from oil palm plantation is taken into account. Referring to the Guthrie method, the economic indicators including the net present value (NPV) and the payback period are estimated at around 0.9 M$ in the 15th year and 9 years, respectively, if the CPO purchase price and the GD selling price are assumed to be $0.47/kg CPO and $1.98/kg GD, respectively, and the increased annual carbon credit is taken into account.
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Palm oil conversion to bio-jet and green diesel fuels over cobalt phosphide on porous carbons derived from palm male flowers
(2020-06-01)
Kaewtrakulchai, Napat
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Kaewmeesri, Rungnapa
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Itthibenchapong, Vorranutch
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Eiad-Ua, Apiluck
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Faungnawakij, Kajornsak
Porous carbon was successfully synthesized from palm male flowers (PMFs), using microwave-assisted potassium hydroxide (KOH) activation and was used as a catalyst support for the conversion of palm oil into bio-hydrocarbons, in fractions of green diesel and bio-jet fuel. Palm male flower-derived porous carbon (PC), consolidated with well dispersed cobalt phosphide (CoP) nanoparticles, was synthesized by simple wet-impregnation with subsequent thermal treatment. The physicochemical properties of the synthesized CoP/PC catalysts were evaluated by various techniques including proximate and ultimate elemental analysis, FTIR, XRD, N<inf>2</inf> sorption, SEM, TEM–EDS, and NH<inf>3</inf>-temperature programmed desorption (TPD). The effects of the pyrolysis temperatures (600−900◦ C), used for the impregnated samples before the reduction process, on catalyst properties and catalytic performance were investigated. Moreover, the effect of a liquid hourly space velocity of 0.5–1.5 h−1 and reaction temperatures of 340–420◦ C was studied in the palm oil conversion. The catalyst pyrolyzed at 600◦ C possessed the greatest particle dispersion and surface area, and showed the highest yield of liquid hydrocarbon product (C9–C18). We also found that the high pyrolysis temperature above 800◦ C partially transformed the Co<inf>2</inf> P phase into CoP one which significantly exhibited higher cracking activity and bio-jet selectivity, due to the improved acidity of the catalyst.

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