Victoria Gutierrez - Academia.edu (original) (raw)

Papers by Victoria Gutierrez

Research paper thumbnail of Liquid phase hydrogenation of crotonaldehyde over Au/CeO2 catalysts

Applied Catalysis A: General, 2009

Three Au/CeO2 catalysts, with different specific surface area (80, 150 and 240m2/g) were tested f... more Three Au/CeO2 catalysts, with different specific surface area (80, 150 and 240m2/g) were tested for the hydrogenation of crotonaldehyde in liquid phase. Reactions were carried out with molecular hydrogen as the reductant, in a batch reactor using isopropanol as the solvent, at 80°C and 1MPa. The high surface area catalyst (Au/CeO2, 240m2/g) showed a selectivity towards crotyl alcohol of 29%.

Research paper thumbnail of Pyrolytic coproduction of bio-char and upgraded bio-oils from abundant agro-industrial wastes

Brazilian Journal of Chemical Engineering, 2021

The co-production of bio-char and upgraded bio-oil by fast pyrolysis of raw and sulfuric-acid pre... more The co-production of bio-char and upgraded bio-oil by fast pyrolysis of raw and sulfuric-acid pretreated agro-industrial wastes (corn cob, sugarcane bagasse and sunflower seed hull) was investigated to valorize wastes as sources of value-added products (VAPs) following the circular bio-economy system. To this end, proximate and elemental analyses were performed, and adsorption properties were determined in pyrolysis products. Bio-char and bio-oil yields from raw wastes ranged 28-33% and 30-35%, respectively. For all wastes, acid pretreatment increased the solid fraction and caused a reduction of the liquid one, compared to untreated wastes. Pyrolysis of raw wastes led to the co-production of bio-chars and bio-oils with different applications. Bio-chars could be put in for soil amendment, primarily due to high ashes concentration, mesoporosity, and elevated cation exchange capacity; whereas, bio-oils could be upgraded by water addition, leading to a source for carrying out reforming reactions in the context of hydrogen production. Properties of bio-chars from acid washed biomasses enabled them for pollutant remediation, due to their high specific surface and microporosity features. The corresponding bio-liquid was a stable-to-storage material, being a practical source of furfural. These findings emphasize that lignocellulosic wastes can be envisaged as starting materials for producing VAPs via pyrolysis.

Research paper thumbnail of Base-free direct synthesis of alkynylphosphonates from alkynes and H-phosphonates catalyzed by Cu2O

The Journal of organic chemistry, Jan 3, 2016

A simple and mild methodology for the direct synthesis of alkynylphosphonates is presented. The r... more A simple and mild methodology for the direct synthesis of alkynylphosphonates is presented. The reaction of a variety of terminal alkynes with dialkyl phosphites in the presence Cu2O (14 mol%) led to the formation of the corresponding alkynylphosphonates in good to excellent yields. Reactions are performed under air, in acetonitrile as solvent, and in the absence of base or ligand additives. This new methodology is compatible with the presence of a wide variety of functional groups on the starting alkynes and can be scaled-up to a gram-scale.

Research paper thumbnail of Highly selective copper nanoparticles for the hydrogenation of α,β-unsaturated aldehydes in liquid phase

Applied Catalysis A: General, 2013

Unsupported copper nanoparticles (CuNPs), 3-4 nm in size, are obtained from the reduction of the ... more Unsupported copper nanoparticles (CuNPs), 3-4 nm in size, are obtained from the reduction of the corresponding metal chloride through an electron transfer from a lithium arenide. CuNPs are tested for the liquid phase hydrogenation of cinnamaldehyde in batch conditions by using H 2. High activity and selectivity to cinnamyl alcohol (87%, at high conversion) are reached. When CuNPs are supported on MCM-41 and on high surface area CeO 2 , TEM and XRD characterization shows that the nanometric size of copper is retained. For the hydrogenation of crotonaldehyde or of cinnamaldehyde, CuNPs/MCM-41 and CuNPs/CeO 2 are less active and less selective than unsupported nanoparticles. However the selectivity levels reached by these catalysts are higher than those obtained over noble metal (Au and Pt) based catalysts, tested under the same reaction conditions. The catalytic properties of supported and unsupported CuNPs would be related to the nanometric size of copper.

Research paper thumbnail of Selective hydrogenation of cinnamaldehyde in supercritical CO2 over Pt/SiO2 and Pt/HS-CeO2: An insight about the role of carbonyl interaction with supercritical CO2 or with ceria support sites in cinamyl alcohol selectivity

Applied Catalysis A: General, 2013

The selective hydrogenation of cinnamaldehyde by a RhCl(TPPTS) 3 aqueous solution, ex situ synthe... more The selective hydrogenation of cinnamaldehyde by a RhCl(TPPTS) 3 aqueous solution, ex situ synthesised from RhCl 3 • nH 2 O and TPPTS (tris(M-sulphonatophenyl)phosphine) with pH control by NaOH solution, was investigated under a biphasic (water/toluene) system in a batch reactor. The hydrogenation more usually occurred at C&C bonds, giving hydrocinnamaldehyde as the main product. Important parameters were varied carefully in order to maximise the selectivity toward hydrocinnamaldehyde for which the highest selectivity of 99.9% was achieved. Both the kinetic and mass transfer aspects were also evaluated and the results implied that the biphasic system was under mass transfer control. In addition, supported aqueous phase (SAP) catalysts of the RhCl(TPPTS) 3 solution supported on fine silica were prepared and tested for the selective hydrogenation of cinnamaldehyde under similar conditions for comparison and they gave a very high selectivity to hydrocinnamaldehyde which was an advantage, although their activity was lower than the biphasic catalysts. The mass transfer characteristic in SAP catalysis was also evaluated using a first-order film model.

Research paper thumbnail of Liquid phase selective hydrogenation of cinnamaldehyde over copper supported catalysts

Applied Catalysis A: General, 2012

The selective hydrogenation of cinnamaldehyde is carried out in a batch reactor, at 100 • C and 1... more The selective hydrogenation of cinnamaldehyde is carried out in a batch reactor, at 100 • C and 1 MPa of H 2 using isopropyl alcohol as the solvent, over a series of copper supported catalysts: Cu/Al 2 O 3 , Cu/SiO 2 Cu/MCM-48, Cu/CeO 2 and Cu/␣-Fe 2 O 3. The selectivity of the samples is compared with that corresponding to Pti/SiO 2. Reduced Cu/Al 2 O 3 and Cu/SiO 2 showed lower selectivity to the cinnamyl alcohol (16-22%) than Pt/SiO 2 (35%), at 15% of conversion. Following a calcination at 300 • C both, activity and selectivity of copper catalysts were increased. The calcined surface would hydrogenate C O bond by hydrogen transfer from the solvent. TPR, XRD and FTIR of adsorbed CO showed that Cu (I) species are stabilized on the mesoporous structure of MCM-48. This particular feature renders Cu/MCM-48 a selective catalyst, reaching high selectivity values (51%, at 15% of conversion). Cu/CeO 2 and Cu/␣-Fe 2 O 3 showed higher selectivity than Pt based catalyst due to a promotion of the catalytic properties of copper by reduced support species.

Research paper thumbnail of Solid phosphoric acid catalysts based on mesoporous silica for levoglucosenone productionviacellulose fast pyrolysis

Journal of Chemical Technology & Biotechnology, 2018

Biochemicals are interesting alternatives for biomass valorization owing to their much higher add... more Biochemicals are interesting alternatives for biomass valorization owing to their much higher added value compared to biofuels and energy products. Several methods for the production of valuable chemicals such as levoglucosenone (LGO) via thermochemical processes over solid acid catalysts are being investigated due to their important advantages compared to conventional biomass acid impregnation techniques. The present work explores the synthesis of catalytic materials for the production of this platform molecule.

Research paper thumbnail of Direct synthesis of .beta.-ketomethylenetriphenylphosphoranes from readily available phosphonium salts

The Journal of Organic Chemistry, 1988

6.46 (dd, 2 H, J = 2, 8 Hz, 5”-H), 6.94 (9, 1 H, 3'-H), 7.06 (s, 1 ... (12) Sheldrick, GM SH... more 6.46 (dd, 2 H, J = 2, 8 Hz, 5”-H), 6.94 (9, 1 H, 3'-H), 7.06 (s, 1 ... (12) Sheldrick, GM SHELXS-86, program for crystal structure de-termination; University of Gottingen, Federal Republic of Germany, 1986. (13) Main, P.; Lessinger, L.; Woolfson, MM; Germain, G.; Declerq, S. P. ...

Research paper thumbnail of Synthesis of Myrtenal through Allylic Oxidation of α-Pinene over a Pd/SeO2/SiO2 Catalyst

The 24th International Electronic Conference on Synthetic Organic Chemistry, 2020

SeO2 based samples are tested for the oxidation of α-pinene, in liquid phase employing ethanol as... more SeO2 based samples are tested for the oxidation of α-pinene, in liquid phase employing ethanol as the solvent. Commercial SeO2 was tested under both reflux and under 6 atm O2 pressure. At conversion levels of approximately 40%, the yield to myrtenal was much higher in the latter (34.4%) than in the former case (18.0%) due to the high oxidant species availability. Besides the high yield attained at relatively short reaction time. A palladium promoted selenium dioxide supported catalyst (Pd/SeO2/SiO2) was prepared, characterized, and submitted to the catalytic test. Selenium dioxide (14.4%) was strongly fixed to the silica support. Upon the palladium introduction (0.98%), the reducibility of SeO2 is modified, which originates a selenium species activation towards the allylic oxidation. A 12% conversion level is attained over Pd/SeO2/SiO2 following 8 h of reaction time, employing ethanol as the solvent at 134 °C. The main product is myrtenal, being obtained with a selectivity of 62%. Over oxidation products are not detected. The palladium/selenium dioxide sample is easy to handle with and its recuperation following the reaction in liquid phase is possible.

Research paper thumbnail of Stable and efficient metal-biochar supported catalyst: degradation of model pollutants through sulfate radical-based advanced oxidation processes

Biochar, 2020

This study focuses on the synthesis of metal-based biochar catalysts and their catalytic activati... more This study focuses on the synthesis of metal-based biochar catalysts and their catalytic activation of peroxymonosulfate (PMS, HSO 5 −) for the degradation of three different wastewater model pollutants employing advanced oxidation processes (AOP). Iron, copper, and two different cobalt-based catalysts were prepared and evaluated. The catalysts were supported on a biochar obtained from the pyrolysis of woody pruning wastes. They were characterized by C, H, and N elemental analysis, X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The metal content in each catalyst was determined by means of atomic absorption spectroscopy (AAS). The degradation reactions of benzoic acid (BA), catechol (C), and cinnamic acid (CA) were carried out in a lab scale batch glass reactor and were followed by UV-Visible spectroscopy (UV-Vis). A colorimetric technique was employed to verify the presence of oxidant during the reaction progress. The catalyst/oxidant optimal ratio was determined for the cobalt catalysts. The mineralization degree of the pollutants after the degradations was verified by means of total organic carbon (TOC) content in the residual liquids. After 4 h of reaction, the maximum mineralization was reached when C was treated with a cobalt-based catalyst (> 80%), and its stability was evaluated through successive cycles of use.

Research paper thumbnail of Conversion of sunflower seed hulls, waste from edible oil production, into valuable products

Journal of Environmental Chemical Engineering, 2019

Sunflower seed hulls are an abundant waste produced by the edible oil industry. Pyrolysis was ass... more Sunflower seed hulls are an abundant waste produced by the edible oil industry. Pyrolysis was assessed as a way of turning this material into a liquid rich in valuable products, as well as leading to densification of this voluminous waste. In pursuing this, raw and pre-treated hulls were subjected to fast pyrolysis in a vertical reactor, at 450°C under 200 ml.min-1 of N2. Pre-treatments of sunflower seed hulls consist in washing the material with 15% m/v phosphoric, sulfuric acid solution and 15% m/v sodium hydroxide solution. Then the material undergoes a hydrothermal treatment at 180°C. Raw and pre-treated hulls were characterized prior to pyrolysis by using Proximate and Ultimate Analysis and by TGA/DTG. Pre-treatments lead to substantial modifications in the characteristics of waste hulls producing different bio-oils with diverse compositions. A kinetic study of these pyrolysis reactions was performed in order to determine Ea and rate constants for biomass waste conversion. Hydrothermal pre-treatment leads to selective extraction of hemicellulose, which results in a bio-oil that is highly rich in levoglucosan. Sulfuric and phosphoric acid washing produce lower liquid yields when compared to raw hulls. The bio-oil from phosphoric acid pre-treatment shows a notably high concentration of furfural. NaOH pre-treatment results in an unstable bio-oil, which is rich in tar precursors.

Research paper thumbnail of Liquid phase hydrogenation of crotonaldehyde over Au/CeO2 catalysts

Applied Catalysis A: General, 2009

Three Au/CeO2 catalysts, with different specific surface area (80, 150 and 240m2/g) were tested f... more Three Au/CeO2 catalysts, with different specific surface area (80, 150 and 240m2/g) were tested for the hydrogenation of crotonaldehyde in liquid phase. Reactions were carried out with molecular hydrogen as the reductant, in a batch reactor using isopropanol as the solvent, at 80°C and 1MPa. The high surface area catalyst (Au/CeO2, 240m2/g) showed a selectivity towards crotyl alcohol of 29%.

Research paper thumbnail of Pyrolytic coproduction of bio-char and upgraded bio-oils from abundant agro-industrial wastes

Brazilian Journal of Chemical Engineering, 2021

The co-production of bio-char and upgraded bio-oil by fast pyrolysis of raw and sulfuric-acid pre... more The co-production of bio-char and upgraded bio-oil by fast pyrolysis of raw and sulfuric-acid pretreated agro-industrial wastes (corn cob, sugarcane bagasse and sunflower seed hull) was investigated to valorize wastes as sources of value-added products (VAPs) following the circular bio-economy system. To this end, proximate and elemental analyses were performed, and adsorption properties were determined in pyrolysis products. Bio-char and bio-oil yields from raw wastes ranged 28-33% and 30-35%, respectively. For all wastes, acid pretreatment increased the solid fraction and caused a reduction of the liquid one, compared to untreated wastes. Pyrolysis of raw wastes led to the co-production of bio-chars and bio-oils with different applications. Bio-chars could be put in for soil amendment, primarily due to high ashes concentration, mesoporosity, and elevated cation exchange capacity; whereas, bio-oils could be upgraded by water addition, leading to a source for carrying out reforming reactions in the context of hydrogen production. Properties of bio-chars from acid washed biomasses enabled them for pollutant remediation, due to their high specific surface and microporosity features. The corresponding bio-liquid was a stable-to-storage material, being a practical source of furfural. These findings emphasize that lignocellulosic wastes can be envisaged as starting materials for producing VAPs via pyrolysis.

Research paper thumbnail of Base-free direct synthesis of alkynylphosphonates from alkynes and H-phosphonates catalyzed by Cu2O

The Journal of organic chemistry, Jan 3, 2016

A simple and mild methodology for the direct synthesis of alkynylphosphonates is presented. The r... more A simple and mild methodology for the direct synthesis of alkynylphosphonates is presented. The reaction of a variety of terminal alkynes with dialkyl phosphites in the presence Cu2O (14 mol%) led to the formation of the corresponding alkynylphosphonates in good to excellent yields. Reactions are performed under air, in acetonitrile as solvent, and in the absence of base or ligand additives. This new methodology is compatible with the presence of a wide variety of functional groups on the starting alkynes and can be scaled-up to a gram-scale.

Research paper thumbnail of Highly selective copper nanoparticles for the hydrogenation of α,β-unsaturated aldehydes in liquid phase

Applied Catalysis A: General, 2013

Unsupported copper nanoparticles (CuNPs), 3-4 nm in size, are obtained from the reduction of the ... more Unsupported copper nanoparticles (CuNPs), 3-4 nm in size, are obtained from the reduction of the corresponding metal chloride through an electron transfer from a lithium arenide. CuNPs are tested for the liquid phase hydrogenation of cinnamaldehyde in batch conditions by using H 2. High activity and selectivity to cinnamyl alcohol (87%, at high conversion) are reached. When CuNPs are supported on MCM-41 and on high surface area CeO 2 , TEM and XRD characterization shows that the nanometric size of copper is retained. For the hydrogenation of crotonaldehyde or of cinnamaldehyde, CuNPs/MCM-41 and CuNPs/CeO 2 are less active and less selective than unsupported nanoparticles. However the selectivity levels reached by these catalysts are higher than those obtained over noble metal (Au and Pt) based catalysts, tested under the same reaction conditions. The catalytic properties of supported and unsupported CuNPs would be related to the nanometric size of copper.

Research paper thumbnail of Selective hydrogenation of cinnamaldehyde in supercritical CO2 over Pt/SiO2 and Pt/HS-CeO2: An insight about the role of carbonyl interaction with supercritical CO2 or with ceria support sites in cinamyl alcohol selectivity

Applied Catalysis A: General, 2013

The selective hydrogenation of cinnamaldehyde by a RhCl(TPPTS) 3 aqueous solution, ex situ synthe... more The selective hydrogenation of cinnamaldehyde by a RhCl(TPPTS) 3 aqueous solution, ex situ synthesised from RhCl 3 • nH 2 O and TPPTS (tris(M-sulphonatophenyl)phosphine) with pH control by NaOH solution, was investigated under a biphasic (water/toluene) system in a batch reactor. The hydrogenation more usually occurred at C&C bonds, giving hydrocinnamaldehyde as the main product. Important parameters were varied carefully in order to maximise the selectivity toward hydrocinnamaldehyde for which the highest selectivity of 99.9% was achieved. Both the kinetic and mass transfer aspects were also evaluated and the results implied that the biphasic system was under mass transfer control. In addition, supported aqueous phase (SAP) catalysts of the RhCl(TPPTS) 3 solution supported on fine silica were prepared and tested for the selective hydrogenation of cinnamaldehyde under similar conditions for comparison and they gave a very high selectivity to hydrocinnamaldehyde which was an advantage, although their activity was lower than the biphasic catalysts. The mass transfer characteristic in SAP catalysis was also evaluated using a first-order film model.

Research paper thumbnail of Liquid phase selective hydrogenation of cinnamaldehyde over copper supported catalysts

Applied Catalysis A: General, 2012

The selective hydrogenation of cinnamaldehyde is carried out in a batch reactor, at 100 • C and 1... more The selective hydrogenation of cinnamaldehyde is carried out in a batch reactor, at 100 • C and 1 MPa of H 2 using isopropyl alcohol as the solvent, over a series of copper supported catalysts: Cu/Al 2 O 3 , Cu/SiO 2 Cu/MCM-48, Cu/CeO 2 and Cu/␣-Fe 2 O 3. The selectivity of the samples is compared with that corresponding to Pti/SiO 2. Reduced Cu/Al 2 O 3 and Cu/SiO 2 showed lower selectivity to the cinnamyl alcohol (16-22%) than Pt/SiO 2 (35%), at 15% of conversion. Following a calcination at 300 • C both, activity and selectivity of copper catalysts were increased. The calcined surface would hydrogenate C O bond by hydrogen transfer from the solvent. TPR, XRD and FTIR of adsorbed CO showed that Cu (I) species are stabilized on the mesoporous structure of MCM-48. This particular feature renders Cu/MCM-48 a selective catalyst, reaching high selectivity values (51%, at 15% of conversion). Cu/CeO 2 and Cu/␣-Fe 2 O 3 showed higher selectivity than Pt based catalyst due to a promotion of the catalytic properties of copper by reduced support species.

Research paper thumbnail of Solid phosphoric acid catalysts based on mesoporous silica for levoglucosenone productionviacellulose fast pyrolysis

Journal of Chemical Technology & Biotechnology, 2018

Biochemicals are interesting alternatives for biomass valorization owing to their much higher add... more Biochemicals are interesting alternatives for biomass valorization owing to their much higher added value compared to biofuels and energy products. Several methods for the production of valuable chemicals such as levoglucosenone (LGO) via thermochemical processes over solid acid catalysts are being investigated due to their important advantages compared to conventional biomass acid impregnation techniques. The present work explores the synthesis of catalytic materials for the production of this platform molecule.

Research paper thumbnail of Direct synthesis of .beta.-ketomethylenetriphenylphosphoranes from readily available phosphonium salts

The Journal of Organic Chemistry, 1988

6.46 (dd, 2 H, J = 2, 8 Hz, 5”-H), 6.94 (9, 1 H, 3'-H), 7.06 (s, 1 ... (12) Sheldrick, GM SH... more 6.46 (dd, 2 H, J = 2, 8 Hz, 5”-H), 6.94 (9, 1 H, 3'-H), 7.06 (s, 1 ... (12) Sheldrick, GM SHELXS-86, program for crystal structure de-termination; University of Gottingen, Federal Republic of Germany, 1986. (13) Main, P.; Lessinger, L.; Woolfson, MM; Germain, G.; Declerq, S. P. ...

Research paper thumbnail of Synthesis of Myrtenal through Allylic Oxidation of α-Pinene over a Pd/SeO2/SiO2 Catalyst

The 24th International Electronic Conference on Synthetic Organic Chemistry, 2020

SeO2 based samples are tested for the oxidation of α-pinene, in liquid phase employing ethanol as... more SeO2 based samples are tested for the oxidation of α-pinene, in liquid phase employing ethanol as the solvent. Commercial SeO2 was tested under both reflux and under 6 atm O2 pressure. At conversion levels of approximately 40%, the yield to myrtenal was much higher in the latter (34.4%) than in the former case (18.0%) due to the high oxidant species availability. Besides the high yield attained at relatively short reaction time. A palladium promoted selenium dioxide supported catalyst (Pd/SeO2/SiO2) was prepared, characterized, and submitted to the catalytic test. Selenium dioxide (14.4%) was strongly fixed to the silica support. Upon the palladium introduction (0.98%), the reducibility of SeO2 is modified, which originates a selenium species activation towards the allylic oxidation. A 12% conversion level is attained over Pd/SeO2/SiO2 following 8 h of reaction time, employing ethanol as the solvent at 134 °C. The main product is myrtenal, being obtained with a selectivity of 62%. Over oxidation products are not detected. The palladium/selenium dioxide sample is easy to handle with and its recuperation following the reaction in liquid phase is possible.

Research paper thumbnail of Stable and efficient metal-biochar supported catalyst: degradation of model pollutants through sulfate radical-based advanced oxidation processes

Biochar, 2020

This study focuses on the synthesis of metal-based biochar catalysts and their catalytic activati... more This study focuses on the synthesis of metal-based biochar catalysts and their catalytic activation of peroxymonosulfate (PMS, HSO 5 −) for the degradation of three different wastewater model pollutants employing advanced oxidation processes (AOP). Iron, copper, and two different cobalt-based catalysts were prepared and evaluated. The catalysts were supported on a biochar obtained from the pyrolysis of woody pruning wastes. They were characterized by C, H, and N elemental analysis, X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The metal content in each catalyst was determined by means of atomic absorption spectroscopy (AAS). The degradation reactions of benzoic acid (BA), catechol (C), and cinnamic acid (CA) were carried out in a lab scale batch glass reactor and were followed by UV-Visible spectroscopy (UV-Vis). A colorimetric technique was employed to verify the presence of oxidant during the reaction progress. The catalyst/oxidant optimal ratio was determined for the cobalt catalysts. The mineralization degree of the pollutants after the degradations was verified by means of total organic carbon (TOC) content in the residual liquids. After 4 h of reaction, the maximum mineralization was reached when C was treated with a cobalt-based catalyst (> 80%), and its stability was evaluated through successive cycles of use.

Research paper thumbnail of Conversion of sunflower seed hulls, waste from edible oil production, into valuable products

Journal of Environmental Chemical Engineering, 2019

Sunflower seed hulls are an abundant waste produced by the edible oil industry. Pyrolysis was ass... more Sunflower seed hulls are an abundant waste produced by the edible oil industry. Pyrolysis was assessed as a way of turning this material into a liquid rich in valuable products, as well as leading to densification of this voluminous waste. In pursuing this, raw and pre-treated hulls were subjected to fast pyrolysis in a vertical reactor, at 450°C under 200 ml.min-1 of N2. Pre-treatments of sunflower seed hulls consist in washing the material with 15% m/v phosphoric, sulfuric acid solution and 15% m/v sodium hydroxide solution. Then the material undergoes a hydrothermal treatment at 180°C. Raw and pre-treated hulls were characterized prior to pyrolysis by using Proximate and Ultimate Analysis and by TGA/DTG. Pre-treatments lead to substantial modifications in the characteristics of waste hulls producing different bio-oils with diverse compositions. A kinetic study of these pyrolysis reactions was performed in order to determine Ea and rate constants for biomass waste conversion. Hydrothermal pre-treatment leads to selective extraction of hemicellulose, which results in a bio-oil that is highly rich in levoglucosan. Sulfuric and phosphoric acid washing produce lower liquid yields when compared to raw hulls. The bio-oil from phosphoric acid pre-treatment shows a notably high concentration of furfural. NaOH pre-treatment results in an unstable bio-oil, which is rich in tar precursors.