Esterification of aqueous lactic acid solutions with ethanol using carbon solid acid catalysts: Amberlyst 15, sulfonated pyrolyzed wood and graphene oxide

Nguyen, Van Lap; Bui, Ngoc Quynh; Mascunan, Pascale; Vu, Thi Thu Ha; Fongarland, Pascal; Essayem, N.

doi:10.1016/j.apcata.2017.12.024

Cited by 45 publications

(50 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this paper, we disclose by calorimetry of NH3 adsorption the presence of very strong acid sites on GO with heat of NH3 adsorption as high as 200 kJ/mol, a value similar to that measured on heteropolyacids, H3PW12O40 or Cs2HPW12O40, reported as superacids [18,19]. It is clear that the acidity of GO is significantly higher than that developed by sulfonic groups borne by a classical carbonous matrix such as sulfonated acidic resins (Amberlyst-15) or usual sulfonated carbons characterized by the lower heat of ammonia adsorption of approximately 140 kJ/mol [15,20]. Besides, it is shown here that reGO has a weak acidic surface capable of retaining NH3 rather by physisorption than chemisorption.…”

Section: Discussionsupporting

confidence: 74%

“…The other broad absorption centered around 1200 cm −1 might involve vibrations ascribed to SO 3 H groups. The assignment of the two other thinner vibrations at 1778 cm −1 and 1583 cm −1 remains rather controversial in the literature: the former band around 1780 cm −1 was either ascribed to CO stretching of COOH groups [10,11] or to the bending mode of protonated water clusters [15], while the latter, observed here at 1583 cm −1 on the GO dehydrated 2 h at 150 • C, was attributed as well to νC=C ring vibrations or to adsorbed water molecules [16]. By contrast, the FTIR spectrum of reduced GO shows a strong reduction of the intensity of all the functional groups.…”

Section: Ftir Study Of the Functionnal Groups Of Go And Reduced Gomentioning

confidence: 99%

“…Graphene oxide was synthesized following the modified Hummers' method [15]; 50 mL of sulfuric acid 95% was added to a mixture of 1 g expanded graphite and 0.5 g sodium nitrate under constant stirring at room temperature. After 1 h, the temperature of the solution was cooled to less than 20 • C by ice bath; then, 3 g KMnO 4 was added gradually to the solution.…”

Section: Graphene Oxide and Reduced Graphene Oxide Preparationmentioning

confidence: 99%

See 2 more Smart Citations

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

et al. 2020

Self Cite

View full text Add to dashboard Cite

Graphene oxide addresses increasing interests as a solid acid catalyst working in water for carbohydrate conversion. If there is a general agreement to correlate its unique catalytic performances to its ability to adsorb sugars, the origin of its acidity remains controversial. In this article, we study the acid strength of graphene oxide (GO) prepared by modified Hummers method and that of reduced GO by calorimetry of NH3 adsorption and by FTIR of pyridine adsorption. Very strong acid sites are detected on GO by calorimetry, while reduced graphene oxide (reGO) is not very acidic. The FTIR of pyridine adsorption shows the prevailing presence of Br∅nsted acid sites and a unique feature, the presence of pyridine coordinated by hydrogen bonds. This exceptionally strong Br∅nsted acidity is tentatively explained by the presence of graphene domains decorated by hydroxyl, carboxylic, or sulfonated groups within the GO sheet, resulting in a high mobility of the negative charges which makes the proton free and explains its strong acidity. Accordingly, only GO is active and selective for native cellulose hydrolysis, leading to 27% yield in glucose. Finally, we show that sugar alcohols cannot be formed directly from cellulose using GO combined with Pt/re-GO under hydrogen, explained by the reduction of oxygenated functions of GO. The instability of the functional groups of GO in a reducing atmosphere is the weak point of this peculiar solid acid.

show abstract

Section: Discussionsupporting

confidence: 74%

Section: Ftir Study Of the Functionnal Groups Of Go And Reduced Gomentioning

confidence: 99%

Section: Graphene Oxide and Reduced Graphene Oxide Preparationmentioning

confidence: 99%

See 1 more Smart Citation

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Tests. e activity of the catalysts was evaluated through the esterification reaction between lactic acid 50% (obtained from 85% lactic acid solution by the dilution) and ethanol (mole ratio 1 : 4) at 82°C [29]. e weight ratios of the sulfonated biochar and GO catalysts to lactic acid are 5% and 1%, respectively.…”

Section: Catalyticmentioning

confidence: 99%

Synthesis of Acidic Heterogeneous Catalysts with High Stability Based on Graphene Oxide/Activated Carbon Composites for the Esterification of Lactic Acid

Vu¹,

Nguyen

Nguyen³

2019

Journal of Chemistry

View full text Add to dashboard Cite

In this article, acidic heterogeneous catalysts based on graphene oxide and sulfonated biochar were prepared, characterized, and used for lactic acid esterification to form ethyl lactate. Graphene oxide was supported on activated carbon (GO/AC) to more easily filter the catalyst from the reactants. The catalysts were characterized by such methods as XRD, FT-IR, SEM, BET, and the acid-base titration. Catalytic activity was evaluated through the esterification of lactic acid. As a result, the activity of the catalysts decreased in the following order: graphene oxide > sulfonated biochar ≈ GO/AC >> activated carbon. In addition, the GO/AC catalyst showed good stability with an unchanged yield from the 3rd to the 6th recycling test. These results suggest potential applications for new acidic heterogeneous catalysts based on graphene oxide and sulfonated biochar that could replace homogeneous acids in the future.

show abstract

“…Some metal oxides have been used for esterification of lactic acid with n‐butanol in batch conditions but not reported about catalyst stability. Recently, Nadine Essayem reported the synthesis of ethyl lactate (EL) over carbon solid acid catalysts such as Amberlyst 15, sulfonated pyrolyzed wood and graphene oxide but those were not stable in esterification conditions due to leaching of sulphur in the presence of water . Numerous groups reported esterification of lactic acid in batch conditions.…”

Section: Introductionmentioning

confidence: 99%

Vapor Phase Selective Production of Ethyl Lactate over ZrO₂‐SiO₂ Catalysts Using Lactic Acid and Ethanol

et al. 2018

View full text Add to dashboard Cite

A series of zirconia‐silica catalysts with different weight % of ZrO2 were prepared by sol‐gel method and tested for the vapor phase production of ethyl lactate via esterification of lactic acid using ethanol. Under the optimized conditions, 99% selectivity to ethyl lactate and complete conversion of lactic acid is observed over 7% ZrO2/SiO2 catalyst at 453 K with 1:15 molar ratio of lactic acid and ethanol. The catalysts were studied for various properties using XRD, FTIR, NH3‐TPD, N2 sorption, Pyridine FT‐IR and UV‐Vis. The results revealed that 7% ZrO2/SiO2 possesses amorphous phase and sufficient number of acidic sites which are helpful in achieving higher activity.

show abstract

Esterification of aqueous lactic acid solutions with ethanol using carbon solid acid catalysts: Amberlyst 15, sulfonated pyrolyzed wood and graphene oxide

Cited by 45 publications

References 31 publications

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

Synthesis of Acidic Heterogeneous Catalysts with High Stability Based on Graphene Oxide/Activated Carbon Composites for the Esterification of Lactic Acid

Vapor Phase Selective Production of Ethyl Lactate over ZrO₂‐SiO₂ Catalysts Using Lactic Acid and Ethanol

Contact Info

Product

Resources

About

Esterification of aqueous lactic acid solutions with ethanol using carbon solid acid catalysts: Amberlyst 15, sulfonated pyrolyzed wood and graphene oxide

Cited by 45 publications

References 31 publications

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

Acid Properties of GO and Reduced GO as Determined by Microcalorimetry, FTIR, and Kinetics of Cellulose Hydrolysis-Hydrogenolysis

Synthesis of Acidic Heterogeneous Catalysts with High Stability Based on Graphene Oxide/Activated Carbon Composites for the Esterification of Lactic Acid

Vapor Phase Selective Production of Ethyl Lactate over ZrO2‐SiO2 Catalysts Using Lactic Acid and Ethanol

Contact Info

Product

Resources

About

Vapor Phase Selective Production of Ethyl Lactate over ZrO₂‐SiO₂ Catalysts Using Lactic Acid and Ethanol