Catalysis Letters最新文献

The chemo-selective hydrogenation of quinoline is a critical reaction, producing high-value chemical intermediates such as pharmaceuticals, pesticides, and dyes. Traditional heterogeneous catalysts for this reaction typically require higher and more stringent reaction conditions due to the stable π-conjugated structure of quinoline. To achieve this transformation, some innovative strategies must be developed to enhance the catalytic properties of conventional catalysts. In this work, adenine was employed as a novel structural modifier to finish Co-MOFs materials and prepare Pd/Co-MOFs_(A) catalysts. The introduction of adenine efficiently enhanced structural stability and catalytic efficiency of original Pd/Co-MOFs catalyst. A remarkable increase of approximately 441% in catalytic conversion was obtained compared to the unmodified catalyst. This substantial improvement in catalytic performance could be attributed to mass transfer enhancement. The N-heterocyclic conjugated structure facilitated π–π stacking interactions and hydrogen bonding between the catalyst and quinoline, thereby accelerating mass transfer and improving catalytic efficiency. Under mild reaction conditions, the Pd/Co-MOFs_(A) catalyst fully demonstrated its high catalytic performance, achieving a 99.0% quinoline conversion and a 99.9% selectivity toward 1,2,3,4-tetrahydroquinoline. Finally, the Pd/Co-MOFs_(A) catalyst presented in this study could pave the way for enhancing the catalytic performance of traditional heterogeneous catalysts through alkaloid modification in quinoline hydrogenation.

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A strategy was proposed for the synthesis of Mo₂C/C composite as an efficient electrocatalyst through electrospinning and calcination. PVP and PAN were utilized as electrospinning precursors for comparative analysis. Morphological characterization revealed that an electrospinning solution with the viscosity in the range of 2–5 mPa·S was conducive to the formation of spherical morphology. Under calcination at nitrogen atmosphere, as-electrospun Mo@PVP-1 and Mo@PAN-1 samples transformed into Mo₂C/C with bead-like structure at 900 and 800 °C, respectively. Compared to PVP, PAN exhibited greater resistance to deformation at elevated temperature, resulting in better-dispersed spherical Mo₂C/C composite. The synthesized Mo₂C/C exhibited good electrocatalytic activity for hydrogen evolution reaction. The Tafel slopes of Mo₂C/C prepared from Mo@PVP-1-900 and Mo@PAN-1-800 were 75.85 and 164.7 mV·dec⁻¹, respectively. This work contributes to the understanding of synthetic process of spherical Mo₂C/C composites through electrospinning, providing an effective way to improve material performance.

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Mo₂C/C composites were synthesized by calcination with different polymer solutions (PAN and PVP) by electrostatic spraying, and their performance as catalysts was tested.

One of the best renewable energy sources that can replace petroleum fuel is biodiesel, which may be produced through catalytic transesterification. However, there is a risk that some of these plant-based biofuels may actually promote bacterial colonies while damaging the methyl esters that are synthesised. The present study aimed to assess the cadmium oxide (CdO) nanocatalyst in the catalytic transesterification of Lepidium aucheri seed oil into fatty acid methyl esters (FAMEs) as a source of Biodiesel and the potential of the seed oil against bacterial activities as possible source of bio-additive for biofuels. For biodiesel synthesis, a cadmium oxide (CdO) nanocatalyst was synthesised and characterised via SEM, FT-IR, and EDX. The biodiesel yield using the CdO catalyst was 88% when the reaction was carried out for 2 h at 75 °C with an ideal mixture of 12:1 oil to methanol molar ratio and a catalyst concentration of 2% utilising LASO. The antibacterial activity of two bacterial strains (Escherichia coli and Bacillus subtilis) was investigated via the agar well diffusion method. The maximum antibacterial activity was observed with 100 µl of LASO, which inhibited Bacillus subtilis and Escherichia coli, resulting in a 24.7 mm inhibition zone. It was also put to use in the biodiesel synthesis process, trans-esterifying nonedible LASO into methyl esters for the synthesis of Biodiesel. The synthesised biodiesel was subjected to analyses via GC‒MS, FT‒IR, and NMR. The investigation concluded that the biodiesel sector may be used the feedstock as a raw material at the commercial level.

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The catalytic oxidative esterification of 1, 2-propanediol to methyl lactate in a base-free methanol system over Cu-modified Au/HAP catalysts was investigated. The catalysts demonstrated efficient activity in converting 1, 2-propanediol to methyl lactate without any base additives, achieving a conversion of 91.2% and a selectivity of 45% for methyl lactate under optimized conditions of 160 °C, 2 h, and 1.0 MPa O₂ over 2Au12Cu/HAP catalyst. The Au sites were identified as pivotal in catalyzing the oxidation of 1, 2-propanediol, and the basic sites of HAP was hypothesized to play a similar role with base additives to enhance the catalytic activity of Au. Furthermore, modification of Cu to Au was observed to promote the oxidation of the hydroxyacetone intermediate to methyl lactate while effectively suppressing the over-oxidation of methyl lactate, thus increased selectivity of methyl lactate.

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1,2-propanediol was convertedto methyl lactateefficientlyin a base-free methanol system over Au-Cu/HAP catalysts

Copper oxide nanoparticles incorporated-zeolite supported-graphitic carbon nitride (CuO/g–C₃N₄/Zeolite Y) catalyst was fabricated through a facile hydrothermal method, in which CuO nanoparticles were produced via precipitation. The synthesized CuO/g–C₃N₄/Zeolite Y was examined using characterization techniques such as FT-IR, XRD, XPS, TEM, SEM, EDX, TG, BET, DRS, and PL. BET analysis revealed that integrating zeolite and CuO has increased the surface area of graphitic carbon nitride. Increased separation efficiency and reduced recombination rates of photogenerated electrons and holes in CuO/g–C₃N₄/Zeolite Y were confirmed by photoluminescence studies. The CuO/g–C₃N₄/Zeolite Y catalyst exhibits enhanced efficiency for degrading MB and CV dyes compared to pristine g-C₃N₄ under sunlight exposure. The active species studies demonstrated that hydroxyl radicals, superoxide anion radicals and holes involve in the photocatalytic destruction of pollutants. Additionally, the CuO/g–C₃N₄/Zeolite Y composite efficiently degraded the antibiotic ceftazidime. Intermediates generated during the degradation process were identified, and plausible degradation pathways for ceftazidime were proposed through LC–MS analysis. This study implies that the synthesized catalyst can be used in the wastewater cleanup process to eliminate persistent organic contaminants and pharmaceutical pollutants under sunlight irradiation.

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Excess sludge in the paper industry is a hazardous solid waste that requires urgent and proper disposal for environmental protection and resource utilization. In this study, a novel magnetic biochar (Fe-SDBC) synthesized from paper sludge through one-step pyrolysis was employed to activate persulfate (PDS) for the efficient removal of acid orange 7 (AO7). The results indicated that Fe-SDBC could effectively activate PDS to remove 97.8% of AO7 within 90 min, with 89.4% removed within 5 min. Fe-SDBC had unique properties with abundant adsorption and active sites, including iron-containing compounds and oxygen-containing functional groups. The addition concentrations of Fe-SDBC (0.5 g/L) and PDS (10 mM) were optimized based on response surface methodology. Furthermore, Fe-SDBC presented good stability over a wide range of pH (3 ~ 11) and reusability in cyclic experiments. Coexisting ions, such as CO₃²⁻, HCO₃⁻, and PO₄³⁻, had an inhibitory effect on AO7 removal. Both radical and non-radical pathways were proved to be involved in the Fe-SDBC/PDS system for AO7 removal, with singlet oxygen (¹O₂) being the dominant species. Additionally, the degradation pathways were investigated and toxicity assessment was evaluated. This work will provide a potential approach for paper sludge recycling in the wastewater treatment.

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Chlorophenol wastewater has a serious impact on the environment, and it is not easily degraded by traditional methods. The novel electrochemical hydrogen evolution reduction degradation has received widespread attention, among which the electrocatalytic performance of the electrode is particularly critical. In this study, Pd-Fe₂O₃-coated nickel foam electrode (Pd-Fe₂O₃-Ni) was prepared by annealing on Fe–Ni and introducing Pd into Fe₂O₃. Its degradation performance is better than that of the original nickel foam (Ni) and Fe₂O₃-Ni electrodes. The removal of 4-chlorophenol by Pd-Fe₂O₃-Ni was 98.2%, which was 1.4–1.52, 10–12 and 10.3–11.4 times higher than that of the unannealed Pd-Fe₂O₃-Ni, Ni, and Fe₂O₃-Ni, respectively. Meanwhile, the Pd-Fe₂O₃-Ni electrode had good stability, and the 4-chlorophenol removal rate was maintained at 92% after five repetitions, which proved the applicability of the Pd-Fe₂O₃-Ni electrode. Therefore, the prepared Pd-Fe₂O₃-Ni is a high-performance electrode for electrochemical reduction and degradation of wastewater.

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The yield of solvent-tolerant cold-active lipase from halo-tolerant Pseudomonas sp. VITCLP4 was improved by applying statistical methods to precisely combine medium components and other conditions. A two-level Plackett–Burman (PB) design was utilized to screen the most significant variables from eleven variables that influence lipase production. Analysis of variance revealed that Tween-80, peptone, and KH₂PO₄ were statistically significant. Optimum levels of selected variables were ascertained by one-factor-at-a-time (OFAT) analysis. The selected three components' optimum values and interactive effects were established by response surface methodology (RSM) using a five-level-three-factor approach based on the central composite design (CCD). The optimized medium containing Tween-80, 0.6% (v/v), peptone, 0.85% (w/v), KH₂PO₄, 0.1% (w/v), yeast extract, 0.1% (w/v), olive oil, 0.2% (v/v) and inoculum size, 0.2% (v/v) resulted in maximum lipase production of 1356 Units mL⁻¹ min⁻¹ with 7.9-fold increase in the yield. This study provides insights into enhancing lipase production statistically with optimized resources that can be utilized in bioprocess studies and industrial applications.

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Selective oxidation of glycerol has been considered to be one of the ways of efficient conversion and utilization of glycerol. This paper reported the preparation of a series of supported non-noble metal catalysts on Ti modified SBA-15 supported by CuCo, a cheap and readily available non-noble metal, and evaluated the catalytic effect of the catalysts in the selective oxidation of glycerol to produce tartronic acid. The properties of Cu_xCo_y/Ti-SBA-15 catalysts were characterized by XRD, XPS, FT-IR, BET, SEM and TEM. The results showed that Cu and Co were uniformly distributed on the surface of Ti-SBA-15 and the original structure of SBA-15 was maintained. The catalytic activity of CuO and Co₃O₄ can be improved through the synergistic effect of valence change. In addition, the glycerol conversion was 53.8% and tartronic acid selectivity was 54.5% under the optimal reaction conditions. After five cycles, the catalyst still maintained good reuse performance.

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Biochar, a carbon-enriched material, has been introduced as robust sorbent for the removal of wide array of pollutants. Recently, Biochar functionalized with metals or metal hydroxide composites has gained attention as low-cost, sustainable materials. Layered double hydroxides (LDHs) and biochar interact synergistically to produce composites with significantly improved specific surface area, structural heterogenicity, surface functional groups, stability and adsorptive properties. In this study, composites constructed out on Mg–Fe LDHs supported by biochar (BC) derived from Pinus roxburghii (chir pine) waste are synthesised. Pinus roxburghii biochar (PR-BC-500) was produced at 500 ℃ under inert conditions and used to synthesize biochar incorporated LDH nanostructures (PR-LDH-500) hydrothermally. Nanocomposites were characterized by XRD, FTIR, BET, Raman, Zeta potential, UV, PL, SEM and EDS techniques. The SEM results display the ideal distribution of LDH particles on the surface of biochar, increasing surface area and occupying pores, confirming composite formation. Photocatalytic outcomes demonstrated that the BC particles integrated into the LDH structure demonstrated strong photocatalytic performance as prepared. 93.4% of Methylene Blue was degraded through photocatalytic degradation in the active participation of PR-LDH-500 nanocomposites, whereas PR-BC-500 degraded only 76.8%. The optimal conditions for methylene blue degradation using PR-LDH-500 and PR-BC-500 photocatalysts were achieved at a catalyst dosage of 50 mg, with a maximum degradation of 94% at pH 12 after 240 min of UV irradiation. According to the results, PR-LDH-500 has outstanding feasibility as a durable and inexpensive adsorbent for the purifying dye-tainted aqueous ecosystems.

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