Catalysis Letters最新文献

In this study, highly crystalline ZSM-22 zeolite with a TON topology was synthesized via a seed–template co-assisted hydrothermal method and subsequently modified with low-concentration NH₄Cl to introduce Brønsted acid sites. The characterization of the catalyst revealed its well-defined rod-like crystals (2–5 μm), one-dimensional straight channels (0.46 × 0.57 nm), microporous surface area of 210 m²·g⁻¹, Brønsted-to-Lewis (B/L) acid ratio of 0.45, and excellent thermal stability. Under optimized reaction conditions (270 °C, 3 h, 6 wt% catalyst), the catalyst achieved a 95.01% conversion of oleic acid and a 77.72% yield of isostearic acid. The confinement effect of the 1D channels effectively suppressed undesired side reactions, offering significantly enhanced selectivity compared to commercial zeolites such as ZSM-5. Thermogravimetric analysis demonstrated that calcination at 550 °C successfully removed coke deposits and restored catalyst activity. After five regeneration cycles, the conversion and yield remained at 89.50% and 72.80%, respectively, with less than 6% loss. These findings provide theoretical and technical guidance for the high-value catalytic transformation of biomass-derived fatty acids.

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H-ZSM-22 catalyst with good reusability

To further explore the catalytic versatility of Penicillium expansum lipase (PEL), we investigated and optimized its application in the Pudovik-Abramov reaction. Under environmentally friendly optimized conditions, PEL effectively catalyzed the reaction, yielding valuable α-hydroxyalkylphosphonates with efficiencies reaching up to 94%. Leveraging site-directed mutagenesis, we also probed the potential molecular basis underlying the enzymatic catalysis of the Pudovik-Abramov reaction. Our results demonstrate that although the catalytic mechanism for this reaction differs from that of the enzyme’s native hydrolysis activity, the catalytic histidine residue within the PEL catalytic triad retains an indispensable role in the Pudovik-Abramov reaction. This underscores that key structural elements of the lipase active site, such as the catalytic triad, constitute crucial molecular foundations for its catalytic promiscuity.

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PEL effectively catalyzed the Pudovik-Abramov reaction, yielding valuable α-hydroxyalkylphosphonates. The catalytic histidine residue within the PEL catalytic triadretains an indispensable role in the reaction.

In the western region of Azerbaijan, grape seeds waste products from wine production at “GANJA SHARAB-2” were utilized as a raw material for biodiesel production as an alternative energy source. In this study, biodiesel (fatty acid methyl esters) was synthesized through transesterification reactions of grape seed oil in methanol, using catalysts prepared by modifying natural Aydag zeolite via impregnation with alkaline earth metal oxides (MgO, CaO, SrO). The natural and activated zeolite catalysts were tested under reaction conditions involving a 1:10 molar ratio of oil to methanol at temperatures of 200 °C, 250 °C, and 300 °C for a duration of two hours. The transesterification reactions were carried out using 0.5 g of each catalyst (natural zeolite; 5% SrO/zeolite; 5% MgO/zeolite; 5% CaO/zeolite). The physic and chemical properties of the catalysts were characterized using X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) methods. Among the catalysts and reaction conditions evaluated, the highest triglyceride conversion rate (92.6%) and fatty acid methyl ester yield (98.9%) were achieved using the 5% CaO/zeolite catalyst at 300 °C. Various physicochemical parameters of the obtained biodiesel were determined and their compliance with the international standard ASTM (American Society for Testing and Materials) was studied comparatively. Infrared (IR) spectroscopy confirmed the successful conversion of grape seed oil into biodiesel through transesterification in the presence of activated zeolite catalysts.

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Biodiesel Production from Zeolite Catalysis

Cotton Blue (CB) is a triphenylmethane dye widely used in the textile, biological staining, and paper industries, but its stable aromatic structure makes it nonbiodegradable and harmful to aquatic life. In this study, CoFe₂O₄/bentonite nanocomposite was synthesized by green hydrothermal method using Millettia ferruginea leaf extract as a reducing and capping agent. Characterization of the nanocomposite was carried out with Uv-vis, FTIR, TGA, XRD, SEM, and EDS. The nanocomposite was found to be of 8.14 nm average size with good thermal stability, with no appreciable loss of weight up to 900 °C. Catalytic degradation of CB was assessed under several conditions with 50µL of 5% sodium hypochlorite for 20 min. Maximum efficiency of degradation was 99.5% at a 15 mg dose of catalyst, or equivalent to 0.3150 min^− 1 of the rate constant. Optimum temperature was 45 °C, resulting in a 0.2251 min^− 1 rate constant. The reusability test revealed minimal loss of activity through four successive cycles, with efficiency decreasing gradually from 99.5% to 90.8%. Overall, the results demonstrate the capability of the hydrothermally green-synthesised CoFe₂O₄ nanocomposite as a treatment agent for sustainable dye-containing wastewater.

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Developing low-cost catalysts with high activity and durability is critical for on-demand H₂ generation from sodium borohydride (NaBH₄). Herein, amorphous NiB nanoparticles (1–10 wt% Ni) supported on calcium-deficient hydroxyapatite (HAP) were prepared by wet impregnation. Structural and surface analyses (XRD, TEM, XPS, N₂ adsorption) show well-crystallized HAP, mesoporosity, and uniformly dispersed NiB nanoparticles ((approx )30–50 nm). The 10 NiB/HAP catalyst delivers a hydrogen generation rate of 620 mL.g_Ni^-1. min^-1 at 303 K, exhibits zero-order kinetics with respect to NaBH₄ with an apparent activation energy of 57.2 kJ.mol^-1, and retains 58.3% of its initial activity after five consecutive cycles. XPS reveals Ni²⁺-dominated surfaces for the fresh catalyst and the emergence of Ni⁰/borate species after reaction, consistent with in-situ reduction during hydrolysis. Based on the observed surface functionalities and dispersion, we propose that BH₄^- activation at NiB domains is assisted by Brønsted –POH groups and Lewis-acidic Ca-vacancy sites on HAP, facilitating water activation and hydride–proton coupling. These results identify NiB/HAP as a scalable, low-cost catalyst for portable hydrogen supply.

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Hydrogen energy is widely regarded as one of the most promising alternatives to fossil fuels. This study focuses on the synthesis of an environmentally friendly zwitterionic polymer catalyst, Poly(Quaternized-2-diethylaminoethyl methacrylate) (P(Q-DMA)), was synthesized and evaluated for the first time as a metal-free catalyst in NaBH₄ methanolysis for hydrogen production. Owing to its zwitterionic nature, P(Q-DMA) was designed to interact synergistically with methanol and sodium borohydride through multiple mechanisms, including ion–dipole, ion–ion, and hydrogen-bonding interactions. The structure–function relationship was investigated using surface analysis (BET, SEM and Zeta), chemical characterization (FTIR, TGA), and kinetic modeling. Systematic optimization revealed high catalytic efficiency, achieving a hydrogen generation rate (HGR) of 443.4 mL H₂ min⁻¹ gcat⁻¹ and a mass-specific HGR of 8868.4 mL H₂ min⁻¹ gcat⁻¹, with a low activation energy (Ea) of 19.91 kJ mol⁻¹. The polymer also exhibited good electrocatalytic activity (0.72 mA cm⁻² at 0.8 V in 1 M NaOH + 0.1 M NaBH₄) and stable performance during NaBH₄ electrooxidation. Importantly, zeta potential values shifted from + 13.1 mV before reaction to − 12.2 mV (unwashed) and − 8.43 mV (washed) after reaction, indicating surface modification by adsorbed borate species. These results highlight P(Q-DMA) as a promising biocompatible, metal-free catalyst for scalable hydrogen production and electrochemical applications, aligning with sustainable and clean energy goals.

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The facile preparation of a green zinc-based coordination polymer, Zn-PICA (Zn-poly-imidazole carboxylic acid), which promotes acceptorless dehydrogenative coupling (ADC) to synthesize the pharmaceutically and industrially significant benzimidazole derivatives with a wide substrate scope was herein reported. This novel, tandem/cathcade-type synthetic strategy exhibits high efficiency, atom and step economy towards an ADC reaction involving the condensation of o-phenylenediamine with an aryl alcohol or amine as the substrate to afford the benzimidazole derivatives in moderate to good yields and is found applicable to gram-scale synthesis. The coordination polymer catalyst (Zn-PICA) was characterized by FT-IR, SEM, TEM, EDS and XPS, followed by a proposed mechanism based on a series of control experiments. Finally, the recyclability of Zn-PICA catalytic system was examined and the catalyst was found to retain good activity within five cycles.

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The oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) faces challenges of low efficiency and poor stability when non-noble metal catalysts are used. Herein, a Cu-Ni bimetallic catalyst (Cu₆₇Ni₂₂O_x) was designed, and its oxygen vacancy (O_V) formation and adsorption-oxidation capacity was systematically investigated via scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR), among other techniques. Structural characterizations showed that the (Cu₆₇Ni₂₂O_x catalyst combined amorphous nickel oxide and crystalline copper oxide. Amorphous Ni enhanced surface hydroxylation (13.2%) to promote the adsorption for HMF, while the catalyst’s high O_V concentration (56.2%) facilitated active oxygen transfer. Additionally, the Cu-Ni heterointerface of (Cu₆₇Ni₂₂O_x effectively suppressed particle agglomeration to a certain extent, as evidenced by cycling tests showing over 80% activity retention after 5 cycles. Under optimized conditions, the FDCA yield reached 93.46% within 12 h at 140 °C. This catalyst offers a promising candidate for the sustainable synthesis of FDCA.

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The impacts of PbCl₂ and PbO on Mn–Co catalysts were investigated and compared in the context of low-temperature CO oxidation. The poisoned catalysts were synthesized by impregnating fresh catalysts with aqueous solutions of PbCl₂ and Pb(NO₃)₂, respectively. The activity of the Mn–Co catalyst would be reduced by both Pb species, and PbO was more effective in poisoning it compared to PbCl₂. The Pb species led to a reduction in specific surface area and pore volume. Furthermore, the presence of Pb species decreased the concentrations of Mn³⁺, Co³⁺, and surface lattice oxygen species. In addition, the presence of Pb species led to a decrease in the reducibility, thereby impeding the adsorption activation process of CO as well as the redox cycle. Moreover, the oxidation of CO on the MC catalyst followed the Mars-van Krevelen (MvK) mechanism. CO reacted with Co³⁺ to form the CO–Co³⁺ species. Subsequently, CO–Co³⁺ species reacted with lattice oxygen to generate carbonate species and create oxygen vacancies. The carbonate is further decomposed into CO₂. The presence of Pb inhibited the adsorption of CO and reduced the generation of active intermediates. Besides, the introduction of Pb inhibited the decomposition of carbonate, leading to its accumulation on the catalyst surface, which blocked the active sites and oxygen vacancies.