Cu catalysts supported on CaO/MgO for glycerol conversion to lactic acid in alkaline medium employing a continuous flow reaction system

Bruno, Arthur M.; Simões, Thiago D. R.; Souza, Mariana M.V.M.; Manfro, Robinson L.

doi:10.1039/d0ra06547a

Cited by 16 publications

(13 citation statements)

References 77 publications

(97 reference statements)

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“…Some exceptions are the research presented by Zhang et al [22] and Shimanouchi et al [23], which employed a continuous ow reactor system with alkaline homogeneous media without using catalysts. In previous studies of our group [24,25], employing a continuous ow reaction system, it was observed that reactions carried out with NaOH/glycerol molar ratios greater than 1 show a yield in LA close to 100%. Therefore, for a more sensitive evaluation of the catalyst performance in the reaction, it was decided to use a NaOH/glycerol molar ratio of 0.75.…”

Section: Introductionmentioning

confidence: 90%

Hydrothermal Transformation of Glycerol to Lactic Acid in Alkaline Medium Using Cu Catalysts Obtained from Hydrotalcite-Like Precursors

Moreira

Nogueira

Freitas

et al. 2022

Waste Biomass Valor

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The conversion of glycerol into lactic acid in alkaline medium using heterogeneous catalysts has been highlighted and has proved to be an e cient alternative to the conventional fermentative route. This work investigated the production of lactic acid from glycerol in alkaline medium using copper catalysts obtained from hydrotalcite-like precursors in a continuous ow reaction system and the effect of different copper loading on catalytic behaviors in terms of yield and selectivity to lactic acid. The catalysts were synthesized by the coprecipitation method and characterized by XRF, XRD, N 2 adsorption-desorption, H 2 -TPR, CO 2 -TPD, and the copper dispersion was determined by N 2 O oxidation. The reaction was performed for 30 h at 240°C, 35 atm, using space velocity (WHSV) of 2 h − 1 , solution of 10 vol% glycerol, and NaOH/glycerol molar ratio of 0.75. Although the 30CuHT catalyst presented higher BET surface areas, Cu dispersion, and basicity than the 20CuHT catalyst, the best results in terms of glycerol conversion (96.5%) and yield (64%) to lactic acid were obtained in the catalytic test performed with the 20CuHT catalyst. This result may be related to the reaction steps that occur in the liquid phase in the presence of the hydroxyl group (OH -). Furthermore, the high content of Cu may favor the hydrogenation of the reaction intermediates (2-hydroxypropenal and pyruvaldehyde), increasing the formation of 1,2-propanediol and consequently reducing the yield of lactic acid. Finally, the catalytic activity of the reduced and nonreduced catalysts was investigated, and the results showed that copper oxide also has catalytic activity.However, the reduction of copper oxide provides better results. Statement Of NoveltyThis study is a new contribution to green chemistry production from biomass-derived products, focusing on the production of lactic acid from glycerol in an alkaline medium using copper catalysts obtained from hydrotalcite-like precursors in a continuous ow reaction system. The motivation for this study is the lack of works that evaluate the effect of the copper loading on the catalysts used in transforming glycerol into lactic acid. In addition, no studies were found in the literature that used hydrotalcite-type precursors for this reaction. Some researchers have evaluated the use of copper oxide as a catalyst.However, in this study, it was observed that for higher yields in the conversion of glycerol into lactic acid, it is necessary to use reduced copper (Cu°) catalysts.

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Section: Introductionmentioning

confidence: 90%

Hydrothermal Transformation of Glycerol to Lactic Acid in Alkaline Medium Using Cu Catalysts Obtained from Hydrotalcite-Like Precursors

Moreira

Nogueira

Freitas

et al. 2022

Waste Biomass Valor

Self Cite

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“…A recent paper by the Manfro 60 research group reported the preparation of CaO, MgO, and CaO/MgO-supported CuO catalysts by impregnation and calcination. The various mixed oxide catalysts were denoted as CuMg, CuCa, Cu5CaMg, Cu10CaMg, and Cu15CaMg without O for oxygen.…”

Section: Heterogeneous Catalysts In the Conversion Of Glycerol To Lamentioning

confidence: 99%

“…All the mixed oxides were employed as catalysts for the conversion of glycerol to LA in a continuous flow reaction system with 10 vol% glycerol solution, NaOH/glycerol molar ratio of 1, feed flow of 0.041 mL min −1 at 240 °C and 35 atm. 60 The results are listed in Table 3. The Cu5CaMg, Cu10CaMg, and Cu15CaMg catalysts were found to have higher catalytic activity as well as higher LA selectivity than that obtained by CuMg and CuCa catalysts (Table 3).…”

Section: Heterogeneous Catalysts In the Conversion Of Glycerol To Lamentioning

confidence: 99%

“…68 This important conclusion needs to be considered as an example for assigning the active catalyst in glycerol oxidation started with the high oxidation state metal precursors such as metal oxide. 56,58,60 The highest glycerol conversion and LA selectivity obtained for both catalysts under the optimized conditions are given in Table 4. The reusability of both Pd/C and 5% Pt/C catalysts with metal loading of 10% Pd and 5% Pt, respectively, was tested in the glycerol oxidation at a temperature of 230 °C for 3 h whereby the catalyst was isolated after each run by filtration.…”

Section: Heterogeneous Catalysts In the Conversion Of Glycerol To Lamentioning

confidence: 99%

“…56 A major flaw of this mechanism is that how and in which step the active catalyst would be involved in the whole set of pathways have not been investigated. 56 Nevertheless, the mechanism has also been adopted for the copper-catalysed conversion of glycerol to LA in alkaline solution as reported in two papers by Manfro et al , 28,60 as well as for the catalytic conversion of glycerol to LA in the presence of heterogeneous Ru–Zn–Cu( i ))/HAP catalyst reported by Han et al 32 In the latter mechanism, the first step is again the dehydrogenation of glycerol to GAL, which is followed by the dehydration of GAL to form PAL, and the presence of Zn 2+ ions is assumed to promote the 1,2-hydride shift in PAL forming LA. 32 It was observed that introducing the copper( i ) significantly decreased FA formation.…”

Section: Mechanismsmentioning

confidence: 99%

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A review of the catalytic conversion of glycerol to lactic acid in the presence of aqueous base

Akbulut

Özkâr

2022

RSC Adv.

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Oxygen Vacancy Mediated Reactivity of CaO/CuO Composite for the Synthesis of Amino‐N‐heterocycles

Rajendran,

Madampadi,

Shee

et al. 2023

ChemCatChem

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Utilising the oxygen‐vacancy‐mediated reactivity of CaO/CuO and hydrazine monohydrate in isopropyl alcohol at 353 K, a variety of amino‐derivatives of N‐heterocycles, including pyridine, indole, quinoline, isoquinoline, and benzothiazole, have been selectively synthesised by reducing their nitro analogues. It is demonstrated that CaO/CuO composite is a reusable, solvent‐resilient solid reducing agent that can reduce a variety of nitro‐N‐heterocyclic substrates. The critical role of the structure of CaO/CuO on the nitro‐reduction activity has been studied using spectroscopy and microscopy. DFT simulations indicate the facile formation of oxygen vacancies (EO,vac =‐ 43.4 kJ/mol) on the interface of CaO/CuO surface under reducing environment. The presence of CaO facilitated a stronger interaction of the nitro‐substrate on the oxygen vacant CuO (111) surface, resulting into a significantly lower activation energy (Ea = 21.9 kJ/mol) for N‐O dissociation. The reaction could be scaled up from 1 to 12 mmol of substrate. CaO/CuO is a reusable and a cost‐effective alternative to the conventional catalyst (Pd/C, Pt/C).

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Cu catalysts supported on CaO/MgO for glycerol conversion to lactic acid in alkaline medium employing a continuous flow reaction system

Abstract: The production of lactic acid (LA) from glycerol in alkaline medium was investigated using Cu catalysts supported on CaO, MgO and xCaO/MgO (x = 5, 10, 15 wt%), employing a continuous flow reaction system over a period of 30 h.

Cited by 16 publications

References 77 publications

Hydrothermal Transformation of Glycerol to Lactic Acid in Alkaline Medium Using Cu Catalysts Obtained from Hydrotalcite-Like Precursors

Hydrothermal Transformation of Glycerol to Lactic Acid in Alkaline Medium Using Cu Catalysts Obtained from Hydrotalcite-Like Precursors

A review of the catalytic conversion of glycerol to lactic acid in the presence of aqueous base

Oxygen Vacancy Mediated Reactivity of CaO/CuO Composite for the Synthesis of Amino‐N‐heterocycles

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