Browsing by Author "Gómez Millán, Gerardo"

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A comparative study of water-immiscible organic solvents in the production of furfural from xylose and birch hydrolysate
(2019-04-25) Gómez Millán, Gerardo; Hellsten, Sanna; King, Alistair W.T.; Pokki, Juha-Pekka; Llorca, Jordi; Sixta, Herbert
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Furfural (FUR) was produced from xylose using a biphasic batch reaction system. Water-immiscible organic solvents such as isophorone, 2-methyltetrahydrofuran (2-MTHF) and cyclopentyl methyl ether (CPME) were used to promptly extract FUR from the aqueous phase in order to avoid the degradation to humins as largely as possible. The effect of time, temperature, organic solvent and organic-to-aqueous ratio on xylose conversion and FUR yield were investigated in auto-catalyzed conditions. Experiments at three temperatures (170, 190 and 210 °C) were carried out in a stirred microwave-assisted batch reactor, which established the optimal conditions for achieving the highest FUR yield. The maximum FUR yields from xylose were 78 mol% when using CPME, 48 mol% using isophorone and 71 mol% in the case of 2-MTHF at an aqueous to organic phase ratio of 1:1 (v/v). Birch hydrolysate was also used to show the high furfural yield that can be obtained in the biphasic system under optimized conditions. The present study suggests that CPME can be used as a green and efficient extraction solvent for the conversion of xylose into furfural without salt addition.
Fast furfural formation from xylose using solid acid catalysts assisted by a microwave reactor
(2018-12-15) Gómez Millán, Gerardo; El Assal, Zouhair; Nieminen, Kaarlo; Hellsten, Sanna; Llorca, Jordi; Sixta, Herbert
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The production of furfural (FUR) from xylose was carried out using sulfated zirconia (SZ) on cordierite, alumina on cordierite and commercially-available polymeric solid catalysts (Amberlyst DT and Nafion NR40) to provide insights into the reaction pathways and kinetics for the dehydration of xylose in aqueous phase. Experiments conducted at three temperatures were investigated (170, 190 and 210 °C) in a stirred microwave-assisted batch reactor, which established the optimal conditions to obtain the highest FUR yield as well as extensive and fast xylose conversion. The maximum FUR yields obtained from xylose were 41 mol% when using SZ on cordierite in 2 min (at 210 °C), 43 mol% when using alumina on cordierite in 30 min (at 210 °C) and 48 mol% for an auto-catalyzed system in 60 min (at 210 °C). Based on the experimental results, a reaction mechanism was proposed considering the formation of an intermediate from xylose when solid acid catalysts were added. After five reusability cycles using SZ on cordierite, this catalyst can be regenerated with a similar performance and similar FUR yield on the 6th cycle.
Furfural production from xylose and birch hydrolysate liquor in a biphasic system and techno-economic analysis
(2021) Gómez Millán, Gerardo; Bangalore Ashok, Rahul Prasad; Oinas, Pekka; Llorca, Jordi; Sixta, Herbert
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Furfural has been highlighted as one of the top ten most rewarding bio-based building blocks by the US Department of Energy. In this study, furfural was produced from xylose and birch hydrolysate liquor employing a batch reactor in a biphasic system. The formation of furfural was conducted under auto-catalyzed conditions. 2-sec-Butylphenol was used as extractant to promptly extract furfural from the aqueous phase in order to minimize furfural degradation reactions. The effect of time, temperature, and organic-to-aqueous phase ratio were investigated. The maximum furfural yields from xylose and birch hydrolysate liquor as feedstock under auto-catalyzed conditions when employing 2-sec-butylphenol (SBP) were 59 mol% and 54 mol%, respectively. In the monophasic system when using hydrolysate, 46% furfural was yielded. Based on a techno-economic analysis carried out for furfural, the total investment cost for a plant integrated with an existing pulp mill or bio-refinery is estimated as 14 M€. The minimum selling price of furfural found to be 1.62 € kg−1. With a furfural selling price of 1.93 € kg−1, the payback period is approximately 5 years and an internal rate of return (IRR) of 20.7% is achieved at the end of the project lifetime.
Valorization of low concentration sugar side-stream from dissolving pulp production
(2019) Gómez Millán, Gerardo
School of Chemical Engineering | Doctoral dissertation (article-based)
Among the platform chemicals that can be produced from lignocellulosic biomass, furfural (FUR) constitutes a promising intermediate that can be processed into a variety of advanced end products. In this thesis, the catalytic dehydration of C5-sugars was first developed and optimized using aqueous xylose solutions before the prehydrolysate of birch wood was used as a real substrate. Initially, the use of various metal oxides, such as sulphated zirconium dioxide (SZ) on cordierite and aluminium oxide on cordierite, as catalysts for the conversion of xylose to FUR was investigated and optimized, as they were considered relatively stable under hydrothermal conditions and also exhibit a relatively high proton activity. The maximum FUR yields from xylose were 41 mol% when using SZ on cordierite after 2 min at 210 °C, 43 mol% when using alumina on cordierite for 30 min at 210 °C and 48 mol% using autocatalysis for 60 min at 210 °C. After five reusability cycles with SZ on cordierite, this catalyst can be regenerated with similar performance and FUR yield in the 6th cycle. In addition to heterogeneously catalyzed xylose dehydration into FUR in a monophasic, aqueous system, FUR formation in a biphasic system under auto-catalyzed conditions was also investigated. With water-immiscible organic solvents such as isophorone, cy-clopentyl methyl ether (CPME), 2-methyltetrahydrofuran and 2-sec-butylphenol (SBP) FUR was immediately extracted from the aqueous phase to avoid degradation as far as possible. The maximum FUR yields reached from xylose were 48 mol% when using isophorone, 78 mol% when using CPME and 59% when employing SBP. The use of birch prehydrolysate as a source of C5-sugars led to a yield of 68% FUR at 190 °C when using CPME. When using SBP as organic solvent, a FUR yield of 54% was reached at 190 °C under optimized conditions. In the second phase of the dissertation, Starbon®, a carbonaceous sulfonated acid catalyst, was used in a two-phase system to produce furfural from xylose. A maximum FUR yield and selectivity of 70 mol% was achieved at complete xylose conversion under optimum experimental conditions. This work suggests that functionalized Starbon® can be used as solid acid catalyst for the conversion of C5-sugars into FUR that has significant hydrothermal stability and can be reused for several cycles. Finally, a techno-economic analysis was completed for a FUR plant with a production capacity of 5 kt/a with a minimum selling price to be 1.33 EUR/kg.