Valorisation of xylose to lactic acid on morphology-controlled ZnO catalysts

Paulino, Priscilla N.; Reis, Orlani C.; Licea, Yordy E.; Albuquerque, Elise M.; Fraga, Marco A.

doi:10.1039/c8cy00679b

Cited by 26 publications

(21 citation statements)

References 47 publications

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“…Not only does it add value to biodiesel production chain, but it also opens the way to exploit waste lignocellulose monosaccharides (pentoses and hexoses). In fact, trioses are found as intermediates during the chemocatalytic conversion of pentoses and hexoses to lactic acid via retro‐aldol condensation reactions (Scheme ) . Therefore, understanding their conversion process also aids to widen alternative green routes to lactic acid production, especially as concerning material supply.…”

Section: Introductionmentioning

confidence: 99%

“…In fact, trioses are found as intermediates during the chemocatalytic conversion of pentoses and hexoses to lactic acid via retro-aldol condensation reactions (Scheme 1). [36][37][38][39][40][41][42] Therefore, understanding their conversion process also aids to widen alternative green routes to lactic acid production, especially as concerning material supply.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Brønsted and Water‐Tolerant Lewis Acid Sites in the Cascade Aqueous‐Phase Reaction of Triose to Lactic Acid

et al. 2019

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Aqueous‐phase conversion of glyceraldehyde to lactic acid was investigated over Nb2O5, TiO2, ZrO2 and SnO2 in a fixed‐bed up‐flow reactor. Special attention was given to the catalysts acidity regarding the type, amount, strength and tolerance to water of surface acid sites. These sites were assessed by infrared spectroscopy of pyridine adsorbed on dehydrated and hydrated catalysts as well as by isopropanol decomposition. It was found that Nb2O5 and TiO2 have the highest fraction of water‐tolerant Lewis acid sites (40 and 47 %), while only 6 % was estimated for ZrO2. No relevant Lewis acidity was observed on SnO2, but it was noticed the presence of strong base sites. The transformation of glyceraldehyde into lactic acid proceeded via a cascade reaction in which glyceraldehyde is firstly dehydrated to pyruvaldehyde, followed by its rearrangement to lactic acid with the addition of a water molecule. The dehydration step occurs on Brønsted acid sites and/or on water‐tolerant Lewis acid sites. These latter sites also determine the selectivity to lactic acid. Strong base sites promote glyceraldehyde fragmentation leading to formaldehyde with high selectivity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Role of Brønsted and Water‐Tolerant Lewis Acid Sites in the Cascade Aqueous‐Phase Reaction of Triose to Lactic Acid

et al. 2019

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“…For example, the cleavage of the C1−C2 bond can generate FA, while the cleavage of the C2−C3 bond usually yields GcA. Nevertheless, the generation of FA and GcA as byproducts would result in low selectivity to LaA 51,52. Thus, it seems that controlling the selective cleavage of the C3−C4 bond of fructose plays a crucial role in enhancing the selectivity to LaA.…”

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confidence: 99%

Directing the Simultaneous Conversion of Hemicellulose and Cellulose in Raw Biomass to Lactic Acid

et al. 2020

ACS Sustainable Chem. Eng.

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The production of lactic acid (LaA) directly from actual biomass via a one-step reaction without pretreatment by chemocatalysis has shown high potential for satisfying its enormous demand in widespread applications. Here, we developed an integrated catalytic strategy using Y(III) as the catalyst, enabling the simultaneous conversion of hemicellulose and cellulose components in the actual biomass and selectively yielding LaA with a yield up to 66.3%. The evaluated turnover frequency was 9.7 h–1, the highest value using the actual biomass as the feedstock as far as we know. Combining the result of the experiment with density functional theory studies, we revealed that in the present system, H+, [Y(OH)2(H2O)2]+ species derived from Y3+ hydrolysis cooperatively contributed to the production of LaA. H+ was primarily responsible for the selective fractionation of hemicellulose and cellulose from actual lignocelluloses to soluble polysaccharide fragments as well as the next polysaccharide conversion to the monosaccharide. [Y(OH)2(H2O)2]+ species predominantly contributed to the next monosaccharide conversion to LaA, particularly favoring the electron outflow from C3 to C4–O of fructose derived from glucose isomerization and leading to the accumulation of electronic density on the O atom in C4–O, thereby significantly weakening the C3–C4 bond and directing the selective cleavage of the C3–C4 bond in fructose to LaA. This work might provide a potential strategy for the simultaneous conversion of C5 and C6 sugars in the actual biomass selectively yielding LaA in a cost-effective and environment-friendly way.

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“…Previous reports have identified that basic sites such as O 2− are also reaction sites for this reaction [19] . To investigate the basicity of MOF‐808‐2F, we carried out in situ DRIFTS of adsorbed CO 2 (Figure S13).…”

Section: Resultsmentioning

confidence: 99%

“…Previous reports have identified that basic sites such as O 2À are also reaction sites for this reaction. [19] To investigate the basicity of MOF-808-2F, we carried out in situ DRIFTS of adsorbed CO 2 (Figure S13). We only find the hydroxy groups in MOF-808-2F interacting with the CO 2 probe molecules suggesting that the reaction sites identified in this work differ from the previous work.…”

Section: Determination Of Acid Sites Using In Situ Drifts Of Adsorbed...mentioning

confidence: 99%

Identification of Cooperative Reaction Sites in Metal−Organic Framework Catalysts for High Yielding Lactic Acid Production from d‐Xylose

et al. 2022

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Determining the roles of surface functionality of heterogeneous acid catalysts is important for many industrial catalysts. In this study, the decisive structure of metal−organic frameworks (MOFs) is utilized to identify important features for the effective conversion of d‐xylose into lactic acid. Several acidic MOFs are tested and the combination of Lewis acidity and adjacent hydroxy sites is found to be critical to attain high lactic acid yields. This hypothesis is corroborated experimentally by modification of the MOF to increase such sites, which affords an enhanced lactic acid yield of 79 %, and investigation of the acidity by using in situ FTIR spectroscopy. Density functional theory calculations disclose the cooperative behavior of Lewis acid sites and hydroxy groups in promoting the Cannizzaro reaction, a key step in the production of lactic acid.

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Valorisation of xylose to lactic acid on morphology-controlled ZnO catalysts

Abstract: The activity of ZnO catalysts is significantly driven by the strength of the basic sites determined by their morphology.

Cited by 26 publications

References 47 publications

The Role of Brønsted and Water‐Tolerant Lewis Acid Sites in the Cascade Aqueous‐Phase Reaction of Triose to Lactic Acid

The Role of Brønsted and Water‐Tolerant Lewis Acid Sites in the Cascade Aqueous‐Phase Reaction of Triose to Lactic Acid

Directing the Simultaneous Conversion of Hemicellulose and Cellulose in Raw Biomass to Lactic Acid

Identification of Cooperative Reaction Sites in Metal−Organic Framework Catalysts for High Yielding Lactic Acid Production from d‐Xylose

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