Valorization of low concentration sugar side-stream from dissolving pulp production
- Autores: Gerardo Gómez Millán
- Directores de la Tesis: Jordi Llorca Piqué (dir. tes.), Herbert Sixta (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Roger Gläser (presid.), Xavier Vendrell Villafruela (secret.), Raimo Alén (voc.)
- Programa de doctorado: Programa de Doctorado Erasmus Mundus en Vías Econo-ambientales para Servicios de Energía Sostenible / Environomical Pathways for Sustainable Energy Services por la Universidad Politécnica de Catalunya; Aalto Yliopisto-Aalto University(Finlandia); Akademia Górniczo-Hutnicza(Polonia); Instituto Superior Técnico de Lisboa(Portugal); Kungliga Tekniska Högskolan-The Royal Institute of Technology (Suecia); Politecnico di Torino(Italia); Technische Universiteit Eindhoven-Eindhoven University of Technology(Países Bajos) y École des Mines de Nantes(Francia)
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- Resumen
Lignocellulosic biomass is a promising substitute for fossil-based materials to produce chem i-cals and fuels from renewable resources . Hemicelluloses in lignocellulosic biomass representan attractive feedstock forthe production of versatile platforms for a wide range of applica-tions. Dueto its high xylose content and comparatively low content of lignin and other carbo-hydrate degradation products , the prehydrolysate of hardwood is the most promising source of C5-sugars. The prehydrolysate is generated during the production of dissolving pulp ac-cording to the prehydrolysis-Kraft pulping process.
Among the platform chemicals that can be produced from these bio-based material, furfural (FUR) constitutes a promising intermediate that can be processed into a variety of advanced end products .
The catalytic dehydration of C5-sugars was first developed and optim ized using aqueous xy-lose solutions before the prehydrolysate ofbirch wood was used as a real substrate. lnitially, the use ofvarious metal oxides, such as sulphated zirconium dioxide (SZ) on cordierite and aluminium oxide on cordierite, as catalysts for the conversion ofxylose to FUR was investi-gated and optimized, as they were considered relatively stable under hydrotherm al condi-tions and also exhibit a relatively high proton activity. The maxim um FU R yields from xylose were 41 mol% when using SZ on cordierite after 2 m in at 210 ºC, 43 mol% when using alumina on cordierite for 30 min at 210 ºC and 48 mol% using autocatalysis for60 min at 210 º C. After five reusability cycles with SZ on cordierite, this catalyst can be regenerated with similar per-formance and FUR yield in the 6th cycle .
In addition to heterogeneouslycatalyzed 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, cyclopentyl 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 maxi-m um FUR yields reached from xylose were 48 mol% when using isophorone, 78 mol% when using CPME and 59% when employing SBP.
The use ofbirch prehydrolysate as a source ofC5-sugars led to a yield of68% furfural and 0.01 mmol of5- hydroxymethylfurfural at 190 ºC when using CPME. When using SBP as organ-ic solvent, a furfural yield of 54% was reachedat 190 ºC underoptimi:zed conditions.
In the second phase ofthe dissertation, Starbon®, a carbonaceous sulfonated acid catalyst, was used in a two-phase system to produce furfural from xylose. A maximum furfural yield and selectivity of 70 mol% was achieved at complete xylose conversion under optim um ex-perimental conditions. This work suggests that functional i:zed Starbon® can be used as solid acid catalyst for the conversion of C5-sugars into FUR that has significant hydrothermal stabil-ity and can be reused for several cycles.
