Browsing by Author "Gomez Millan, Gerardo"

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Furfural production from xylose in a bi-phasic set-up
(2017-08-30) Gomez Millan, Gerardo; Hellsten, Sanna; Llorca, Jordi; Sixta, Herbert
A4 Artikkeli konferenssijulkaisussa
The production of furfural (FUR) from xylose was carried out using a biphasic batch reaction system. Isophorone and 2-methytetrahydrofuran (MTHF) have been used to extract FUR and enhance overall furfural yield by limiting its degradation to humins. The effect of time, temperature, and organic to aqueous ratio on xylose conversion and FUR yield were investigated. Experiments conducted at two temperatures (170 and 190 °C) were investigated in a stirred microwave-assisted batch reactor, which established the optimal conditions to obtain the highest FUR yield. The maximum FUR yields obtained from xylose were 82 mol% when using MTHF in 180 min (at 190 °C) and 43 mol% when using isophorone in 180 min (at 190 °C) with an aqueous to organic phase ratio of 5:1.
Furfural production in a biphasic system using a carbonaceous solid acid catalyst
(2019) Gomez Millan, Gerardo; Phiri, Josphat; Mäkelä, Mikko; Maloney, Thaddeus; Balu, Alina; Pineda, Antonio; Llorca, Jordi; Sixta, Herbert
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The formation of furfural from xylose was investigated under heterogeneously catalyzed conditions with sulfated Starbon as a catalyst in a biphasic system. The experiments were perfomed based on the basis of a statistical experimental design. The variables considered were time, temperature and the ratio of aqueous to organic phase. The results indicate that sulfated Starbon is an effective solid acid catalyst for furfural formation. Starbon was characterised by scanning electron microscopy, N2-physisorption, thermogravimetric analysis, diffuse reflectance infrared Fourier transform, Raman spectroscopy and titration with pyridine. The maximum furfural yield and selectivity of 70 mol% were achieved with complete xylose conversion under the optimum experimental conditions. The present paper suggests that functionalized Starbon can be employed as an efficient solid acid catalyst that has significant hydrothermal stability and can be reused for several cycles to produce furfural from xylose.
Recent advances in the catalytic production of platform chemicals from holocellulosic biomass
(2019-04-18) Gomez Millan, Gerardo; Hellsten, Sanna; Llorca, Jordi; Luque, Rafael; Sixta, Herbert; Balu, Alina
A2 Katsausartikkeli tieteellisessä aikakauslehdessä
This Review discusses novel catalytic pathways of lignocellulosic biomass to value-added chemicals including biomass-derived sugar alcohols, organic acids, furans and biohydrocarbons. These production approaches are undertaken by biological, chemical and thermochemical transformations or a combination of them. Nevertheless, the majority of research in this area is focused on the design of heterogeneous catalysts to convert value-added products from holocellulosic biomass. Biorefineries represent the peak of biomass processes in order to produce valuable chemicals and liquid fuels avoiding the utilization of corroding and toxic elements. The aim of the present Review is to offer the readers a broad overview of recent holocellulosic-based chemical and fuels production technologies via heterogeneous catalysis. There is also an overview of the economic aspects to efficiently produce these platform chemicals at industrial scale. To summarize this Review, an outlook and conclusions of the reported processes to date is provided.
A study of the decomposition products of furfural, xylose and isophorone using NMR
(2019-03-24) Gomez Millan, Gerardo; King, Alistair W.T.; Llorca, Jordi; Sixta, Herbert
A4 Artikkeli konferenssijulkaisussa
In recent years we have witness lots of activity to upgrade sugars contained in lignocellulosic biomass into ethanol and other value-added chemicals. An interesting catalytic route, namely the dehydration of sugars (pentoses and hexoses found in lignocellulose) to furans, is considered one of the most promising routes for the production of platform chemicals and fuels [1]. One attractive furanic compound, furfural (FUR), has been identified as a direct or indirect feedstock to more than 80 chemicals [2,3]. The current FUR production uses mineral acids at approximately 200 °C, providing around 50 mol% yield [4]. Low yields in this process are mainly due to FUR decomposition with other compounds via resinification and condensation producing insoluble polymers (humins) [5]. A practical way to inhibit the formation of humins is to extract the FUR instantaneously from the aqueous solution into an organic phase [6]. In this study, the production of FUR from xylose was carried out using a biphasic batch reaction system. Isophorone was used to extract FUR from the aqueous phase to enhance the overall FUR yield by limiting its degradation. Due to their water-immiscibility nature, this organic solvent do not require salt addition, which is a significant advantage over other water-miscible organic solvents. The effect of time, temperature and organic-to-aqueous ratio on xylose conversion and FUR yield were investigated. Experiments conducted at three temperatures (170, 190 and 210 °C) were studied in a stirred microwave-assisted batch reactor, which established the optimal conditions to obtain the highest FUR yield. The maximum FUR yields obtained from xylose was 48 mol% when using isophorone with an aqueous to organic phase ratio of 1:1. In the present work from isophorone, it demonstrates a low selectivity towards FUR (and thus low FUR yield) with decomposition. This suggests that FUR undergoes decomposition reactions, potentially including isophorone as a co-reactant. Alternatively, the rate of degradation of FUR may be increased by an increasing content of water at temperatures approaching 200 °C. These possibilities were investigated by NMR analysis of the degradation of FUR: isophorone molar ratios of 1:1 and 1:10 at 190 °C over 30 min (Figure 1). Potential mechanisms for this degradation might be, for example, Diels-Alder cycloaddition (isophorone as hindered dienophile), Aldol condensation (isophorone C6 reacting as nucleophile at the FUR aldehyde), Baylis-Hillman reaction (isophorone C2 reacting as nucleophile at the FUR aldehyde) and Michael addition (isophorone C3 as α-β unsaturated electrophile). Other reactivity may of course be possible [7-9].