Efficient Catalytic Conversion of Glucose into Lactic Acid over Y-β and Yb-β Zeolites
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ABSTRACT:
SUBMITTER: Shen Z
PROVIDER: S-EPMC9330418 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Amine-modified Sn-β was synthesized to improve the yield of lactic acid produced from Scenedesmus. After studying the growth of Scenedesmus, we selected Scenedesmus with the highest sugar content of 46.7% after 8 days of culture as the reaction substrate. The results showed that the yield of lactic acid from Scenedesmus was greatly increased after being catalyzed by 3-aminopropyltrimethoxysilane (APTMS)-modified Sn-β. After the pretreatment of Scenedesmus in an ice bath ultrasound, under the optimal reaction conditions (190 °C and 5 h), the yield of lactic acid reached the highest (37%). The acid-base characterization results of the catalyst confirmed that there are both Lewis acidic sites and medium-strength basic sites in the catalyst. Both of these sites can promote the hydrolysis of Scenedesmus, while the Lewis acidic sites can promote the production of lactic acid and the basic sites can effectively inhibit the production of the byproduct 5-hydroxymethylfurfural (HMF). This study proved that this amination catalyst is a useful strategy to increase the yield of lactic acid.
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Project description:One of the most interesting intermediates for the chemical industry is acrylic acid, which can be derived from lactic acid by catalytic dehydration in the gas phase. The realization of this reaction is complex due to a strong thermal activation leading to the formation of undesired by-products (acetaldehyde, propanoic acid…) as well as polymerization. We studied this reaction over hydroxyapatites modified by substitution of the hydroxyl groups by fluoride. This notably enabled increasing the selectivity to acrylic acid while reducing the formation of the undesired acetaldehyde. Introduction of fluoride induced a modification of the phosphate ( PO43- ) groups. In the presence of water, fluoride prevented the formation of hydrogenophosphate species ( HPO42- ), which are well-known acid sites responsible for the formation of acetaldehyde by decarboxylation/decarbonylation. Further, we evidenced an important impact of fluoride substitution on crystallinity, specific surface area and on the surface Ca/P ratio. This latter is known to be a key parameter to control the acidity and the basicity of the hydroxyapatites. Using FT-IR spectroscopy with propyne as a probe molecule, we could show that lactic acid was concertedly adsorbed on basic and acid sites, which might be at the origin of the observed superior performances.
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Project description:The utilization of sucrose, an easily accessible disaccharide, in the production of a versatile platform chemical lactic acid (LA), is more attractive than a monosaccharide. In this work, we report a modification approach by 3-aminopropyltrimethoxysilane to introduce an amino group onto the surface of the Sn-Beta Lewis acid catalyst. Using the modified catalyst, a maximum LA yield of 58% was achieved under optimal hydrothermal conditions (190 °C, 4 h) from sucrose, along with a complete conversion and a reduced 5-hydroxymethylfurfural (HMF) yield of 8% compared to Sn-Beta. To evaluate the role of the amino group, different substrates were used as the reactants to produce LA. The experimental results suggested that both fructose and glucose were crucial intermediates in the initial 2 h, whereas glucose is the sole reactant after 2 h. Upon modification, not only the hydrolysis of sucrose was promoted, but the side reaction of HMF formation was also suppressed.
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Project description:Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of common two metal mixed catalyst (Zn-Sn-Beta) prepared via solid-state ion exchange synergistically promoted this reaction. In water without a base, a conversion exceeding 99% for sucrose with a lactic acid yield of 54% was achieved within 2 hours at 190 °C under ambient air pressure. Studies of the acid and base properties of the Zn-Sn-Beta zeolite suggest that the introduction of Zn into the Sn-Beta zeolite sequentially enhanced both the Lewis acid and base sites, and the base sites inhibited a series of side reactions related to fructose dehydration to 5-hydroxymethylfurfural and its subsequent decomposition.
| S-EPMC4879548 | biostudies-literature
Project description:Production of lactic acid from glycerol is a cascade catalytic procedure using multifunctional catalysts combined with oxidative and acidic catalytic sites. Therefore, a series of silver-exchanged phosphomolybdic acid catalysts (AgxH3-xPMo12O40, x?=?1?~?3, abbreviated as AgxPMo) was designed and applied in glycerol oxidation with O2 as an oxidant to produce lactic acid (LA) without adding any base. Among all, total silver exchanged phosphomolybdic acid (Ag3PMo) was found to be the most active one with LA selectivity of 93% at 99% conversion under mild conditions of 5?h at 60?°C. The exceptionally high efficiency was contributed to the generation of strong Lewis acid sites, enhanced redox potentials and water-tolerance. More importantly, Ag3PMo was tolerant in crude glycerol from biodiesel production. And the reaction mechanism was also discussed. Meanwhile, Ag3PMo acted as a heterogeneous catalyst for 12 recycles without loss of activity.
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Project description:A niobium-doped HZSM-5 (H[Nb]ZSM-5) was prepared by a hydrothermal synthesis method. The morphology, phase structure, composition, pore structure, and acid content of the catalyst were characterized using a series of analysis techniques such as scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption, and temperature programmed desorption measurements (NH3-TPD). The H[Nb]ZSM-5 catalyst fully remained within the crystal framework and pore structure of HZSM-5. Meanwhile, introduction of niobium (V) endowed the catalyst with both Lewis acid and Bronsted acid sites. Catalytic fast pyrolysis (CFP) of alkali lignin was carried out through a pyrolysis and gas chromatography-mass spectrometry (Py-GC/MS) at 650 °C and atmospheric pressure. The results indicated that H[Nb]ZSM-5 can efficiently and selectively convert lignin into monoaromatic hydrocarbons (MAHs), compared to the control HZSM-5. Catalyzed by H[Nb]ZSM-5, the content of MAHs and aliphatic hydrocarbons reached 43.4% and 20.8%, respectively; while under the catalysis of HZSM-5, these values were 35.5% and 3.2%, respectively. H[Nb]ZSM-5 remarkably lowered the phenol content to approximately 2.8%, which is far lower than the content (24.9%) obtained under HZSM-5 catalysis.
| S-EPMC10222616 | biostudies-literature
Project description:Highlights • E. coli was engineered to produce fumaric acid from glucose under aerobic conditions.• Fermentation-deficient strain with modified glucose transport was used as a chassis.• Novel design for biosynthesis of the product via modified TCA cycle was implemented.• Artificial bypass of 2-ketoglutarate-succinate semialdehyde-succinate was constructed.• Yield of 0.86 mol/mol, amounting to 86% of theoretical maximum, was achieved. Escherichia coli was engineered for efficient aerobic conversion of glucose to fumaric acid. A novel design for biosynthesis of the target product through the modified TCA cycle rather than via glyoxylate shunt, implying oxaloacetate formation from pyruvate and artificial channelling of 2-ketoglutarate towards succinic acid via succinate semialdehyde formation, was implemented. The main fumarases were inactivated in the core strain MSG1.0 (∆ackA-pta, ∆poxB, ∆ldhA, ∆adhE, ∆ptsG, PL-glk, Ptac-galP) by the deletion of the fumA, fumB, and fumC genes. The Bacillus subtilis pycA gene was expressed in the strain to ensure pyruvate to oxaloacetate conversion. The Mycobacterium tuberculosis kgd gene was expressed to enable succinate semialdehyde formation. The resulting strain was able to convert glucose to fumaric acid with a yield of 0.86 mol/mol, amounting to 86% of the theoretical maximum. The results demonstrated the high potential of the implemented strategy for development of efficient strains for bio-based fumaric acid production.
| S-EPMC8801760 | biostudies-literature
Project description:Sulfonated graphene (SG) was prepared and employed to convert corn stalk and xylose into furfural. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize SG. The effects of reaction time, temperature, substrate loading, catalyst dosage and solvents on the reaction were researched and optimized. SG exhibited high catalytic activity in the conversion of xylose and corn stalk to furfural. A fairly high furfural yield of 96% was achieved at 150 °C from xylose and a 71.9% furfural yield was obtained when using a 10.7 ratio (mass ratio: xylose to SG) at 140 °C. While a 48% furfural yield was obtained from corn stalk (based on the starting combined moles of xylan and glucan in corn stalk; yield was >100%, if based on only xylan) using a substrate loading (corn stalk to catalyst mass ratio) of 2.14 and a 19% 5-hydroxymethylfurfural (5-HMF) yield was obtained. What's more, a 43.9% yield of furfural was obtained in only 20 min. In addition, the reusability of SG was also investigated and shown to have good stability for xylose dehydration.
| S-EPMC9062463 | biostudies-literature
Project description:This study investigated the exchange affinity of Fe3+, Cu2+, and Zn2+ cations in sulfuric acid-purified montmorillonite (S-MMT) to enhance Lewis acid sites and subsequently improve the catalytic conversion of glucose to lactic acid. XRD analysis suggested the successful cation exchange process, leading to structural expansion of the resultant cation exchanged-MMTs (CE-MMTs). XRF and TGA indicated that Zn2+ had the highest exchange affinity, followed by Cu2+ and then Fe3+. This finding was further supported by the results of TPD-NH3 analysis and pyridine-adsorption test, which demonstrated that Zn-MMT had the highest total acid sites (TAS) and the ratio of Lewis acid-to-Brønsted acid surface site (LA/BA). These results indicated dominant presence of Lewis acid sites in Zn-MMT due to the higher amount of exchanged Zn2+ cations. Consistently, time-dependent catalytic studies conducted at 170 °C showed that a 7 h-reaction generated the highest lactic acid yield, with the catalytic performance increasing in the order of Fe-MMT < Cu-MMT < Zn-MMT. The study also observed the impact of adding alcohols as co-solvents with water at various ratios on the conversion of glucose to lactic acid catalysed by Zn-MMT. The addition of ethanol enhanced lactic acid yield, while methanol and propanol inhibited lactic acid formation. Notably, a water-to-ethanol ratio of 30 : 70 v/v% emerged as the optimal solvent condition, resulting in ca. 35 wt% higher lactic acid yield compared to using water alone. Overall, this study provides valuable insights into the cation exchange affinity of different cations in MMT catalysts and their relevance to the conversion of glucose to lactic acid. Furthermore, the incorporation of alcohol co-solvent presents a promising way of enhancing the catalytic activity of CE-MMTs.
| S-EPMC10603823 | biostudies-literature
Project description:The catalytic conversion of glucose into lactic acid (LA) provides an alternative approach for LA production to bio-fermentation. Nevertheless, during the process, the dehydration of glucose and fructose into 5-hydroxymethylfurfural catalyzed by Brønsted acid exists as the main side reaction that leads to the decrease in LA yield. In order to promote the yield and selectivity of LA, a series of acid-base bifunctional Sn-Beta-NH2 catalysts were prepared by post-grafting aminopropyl groups with the surface silanol groups of Sn-Beta zeolite. The catalysts were systematically characterized by X-ray diffraction, N2 adsorption-desorption, elemental analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectra analysis following pyridine adsorption, and CO2 temperature-programmed desorption. The as-prepared Sn-Beta-NH2 catalysts exhibiting both Lewis acid and moderate base sites facilitated the conversion of glucose to LA in competition with undesirable side reactions. In addition, effects of reaction parameters including reaction temperature and time, catalyst dosage, and glucose concentration were investigated. A high LA yield up to 56% was achieved under optimized hydrothermal conditions (190 °C, 2 h), along with a complete conversion of glucose and a 5-hydroxymethylfurfural yield of 7%. The result indicated an alternative modification method of Sn-Beta zeolite for a more favorable LA yield.
| S-EPMC9065098 | biostudies-literature