Catalysis Letters最新文献

Developing simple, durable, and efficient photocatalysts is crucial for achieving environmentally friendly treatment of organic pollutants in water. In this study, nanoscale titanium dioxide (TiO₂) with a size of approximately 5 nm was synthesized using the sol-gel method, and carbon quantum dots (CQDs) with a size of around 3–5 nm were prepared via a vacuum heating process. The preparation conditions could be controlled to render the TiO₂ surface positively charged and the CQDs surface negatively charged. The combination of TiO₂ with CQDs can form a heterojunction, thereby improving light absorption and the separation efficiency of photogenerated carriers. This enables effective light harvesting and carrier transfer, enhancing the photocatalytic performance. The ζ-potentiometer and electron spin resonance (ESR) measurements confirmed the successful fabrication of high-performance TiO₂/CQDs composites through electrostatic attraction, forming an interfacial high-speed channel for the transfer of photogenerated carriers. The results demonstrated that the degradation kinetics rate of TiO₂/CQDs composites reached 0.1345 min^− 1 and degraded 98% of tetracycline hydrochloride within 30 min, which is 6.0 and 4.9 times higher than individual TiO₂ and CQDs, respectively. Based on analytical data and experimental results, the photocatalytic mechanism was elucidated, and intermediates along with reactive species were identified to propose possible degradation pathways. Additionally, antimicrobial testing confirmed the nontoxicity of the constructed catalysts and the complete degradation of the pollutants.

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The conditions for producing 1-methyldecalin with different ratio of cis- and trans-isomers during hydrogenation of 1-methylnaphthalene on a 3%Pt/C catalyst have been studied. A comparison of the dehydrogenation parameters of the obtained 1-methyldecaline samples in a flow-type unit depending on the contact time of the substrate with the 1%Pt/C catalyst has been carried out. On the basis of experimental data, the formal values of the equilibrium constants of the elementary acts of the dehydrogenation reaction were estimated using the computer program of mathematical modeling of complex reaction kinetics KINET 0.8. The obtained results indicate a significant influence on the efficiency of the dehydrogenation reaction not only of the type of ring isomerism (cis- and trans-) in the condensed bicyclic system, but also of the direction of the methyl substituent in one of the six-membered cycles (syn- or anti-).

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A crucial characteristic of perovskite-like oxides is oxygen mobility, which can be enhanced by inducing structural defects through stoichiometry variations during synthesis, thereby boosting the catalytic activity. This study evaluated the effect of structural modifications of LaFeO₃ (LF) and LaMnO₃ (LM) perovskites series on the total oxidation of 2-propanol as a VOC model, a well-known organic solvent. These modifications were performed during synthesis by partially removing the B-site cation or by structural doping in the B-site with another cation (Mn for the LF series and Pd for the LM series). Structural characterization was carried out by XRD and Raman spectroscopy, while the bulk and surface chemical composition were assessed by ICP and XPS, respectively. On the other hand, catalytic activity was performed using a reactivity test with the 2-propanol molecule. The CO-TPR and O₂-TPD measurements were used to characterize the reducibility of the active phase, and the type of oxygen species present in the sample. The catalytic activity results indicated that the modified perovskites showed a difference of 118 °C and 109 °C in the T₉₅ parameter (Temperature at which the conversion of 2-propanol was 95%) relative to pure LF and LM perovskites, respectively. It was also observed that the inclusion of cationic species with high oxidation states enhances the catalytic properties of the materials not only for the doped perovskites but also for the impregnated ones used for comparison purposes. This research demonstrated that stoichiometric variations in modified perovskite-like catalysts significantly improve the catalytic capacity by forming structural defects and modifying redox properties.Kindly check and confirm whether the corresponding author is correctly identified.I confirm that the corresponding author is well identified

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Electronic structure engineering provides an effective route to enhance the mass activity and stability of Pt-based catalysts. In this paper, platinum nanoparticles supported on carbon nanotubes (Pt/CNTs) are prepared by treating the H₂PtCl₆/CNT precursor with argon plasma at different bias. Extensive structural characterization indicates that, compared with positive and zero bias of the substrate, negative bias causes the most defects in CNTs (I_D/I_G = 1.11), results in the lowest valence state of Pt, and achieves the highest Pt loading (4.9 wt%). Meanwhile, the synthesized Pt/CNTs at negative bias (Pt/CNT-V₋) demonstrate significant catalytic activity and exceptional stability in the hydrogen evolution reaction (HER). The Pt/CNT-V₋ catalyst exhibits an overpotential of 45 mV at a current density of 10 mA cm^− 2 and a mass activity of 3.28 A mg^− 1 for the HER in 0.5 M H₂SO₄, surpassing the performance of commercial JM-Pt/C. The overpotential of the Pt/CNT-V₋ catalyst only negatively shifts by 3 mV after 3000 cycles, compared to the 9 mV shift observed for JM-Pt/C. This simple method provides a new strategy for tuning the electronic properties of metals on carbon carriers.

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The solar energy-driven photocatalytic H₂ production from water plays a critical role in achieving decarbonization. One of the key factors determining the water splitting efficiency is the selection of highly effective and stable photocatalysts. Recently, ZnIn₂S₄ (ZIS) based photocatalysts have attracted a great deal of attention due to smaller bandgaps, great light harvesting ability, less toxicity, and ease of fabrication. Therefore, in this study, pristine ZIS and N-doped ZIS (N-ZIS) photocatalysts were synthesized, followed by the investigation of the water splitting reaction under different reaction conditions (e.g., photocatalyst concentration and type and dosage of sacrificial agent). Afterward, the stability of the photocatalyst and sacrificial agent was explored. The results showed that N doping enhanced the evolution of total gases via water splitting reaction. The maximum amount of total gases of 17,559 µmol/g_catalyst was produced at 5mg_{N − ZIS}/35ml_{reaction medium}, methanol as the sacrificial agent, 15 vol% methanol addition for 2 h reaction time. In the stability study of N-ZIS and methanol, a decrease of 6.67% and 29.03% was observed at 3rd cycle, respectively. Overall, the present work provides new insights and knowledge into photocatalytic water splitting over N doping technique for ZIS-based photocatalysts.

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Understanding water adsorption on catalyst surfaces through DFT studies is essential for uncovering interaction mechanisms and enhancing surface reactivity. Defect modulation in oxide-based semiconductors like TiO₂ is pivotal for applications in catalysis, geophysics, and biochemistry. This study uses periodic DFT calculations to investigate water adsorption on Br- and N-doped TiO₂ (101) surfaces. The results indicate that Br and N doping enhances surface reactivity, yielding higher adsorption energy of -0.873 eV for a single water molecule compared to -0.654 eV for undoped TiO₂. An increase in the number of water molecules leads to cluster formation on the modified surface, demonstrating improved adsorption capability. Moreover, Br and N dopants facilitate water dissociation, suggesting an elevated radical’s production. This study is significant as it deepens our understanding of the surface behavior of doped oxide materials, i.e., TiO₂, paving the way for enhanced insights into their catalytic properties and potential applications in heterogeneous catalysis.

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Environmental pollution and bacterial infections are serious problems that mankind has been facing. The simultaneous removal of pollutants and bacteria has attracted widespread attention. Herein, Hydroxyapatite (HAp)/TiO₂ photocatalysts were prepared with anatase TiO₂ exposing {101} and {001} facets as supports. HAp/TiO₂{101} exhibited excellent enhancement in photocatalytic degradation compared to HAp/TiO₂{001} and the pristine TiO₂ nanocrystals. The optimum HAp/TiO₂{101} photocatalyst displayed 77% degradation efficiency of tetracycline (TC) under 300 W xenon lamp within 60 min, as well as excellent stability and reproducibility. The inhibition rates for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are up to 98.3% and 97.2%, respectively. Moreover, it is biocompatible and has a remarkable therapeutic effect on wounds infected with S. aureus. The possible photocatalytic mechanism of HAp/TiO₂{101} was proposed and proved by EPR results. It has been demonstrated that ·O₂⁻, h⁺ as well as their corresponding reactive oxygen species (ROS) play a dominant role in the processes of TC degradation and antimicrobial actions. This work represents the first systematic exploration regarding the capability of HAp/TiO₂{101} which exhibits facet-dependent properties in the photocatalytic degradation, antimicrobial activities, as well as in the treatment of wound infections. It vividly demonstrates its prospective applications in the fields of environmental protection, life, and health.

Organic-pillared vermiculite was applied as the support to fabricate Ru catalyst via adsorption-precipitation method. The catalytic performances of the catalyst were investigated for the selective hydrogenation of levulinic acid (LA) or methyl levulinate (ML) to γ-valerolactone (GVL). The 100% selectivity of GVL and 100% conversion of LA were obtained at 403 K, 4.0 MPa using water as solvent. Moreover, a good recyclability was observed even after 14 reaction cycles as a slight conversion decrease of the LA and no change of the selectivity of GVL. The Characterization of the fresh catalysts and reused catalysts were performed using various techniques including XRD, FT-IR, N₂ adsorption-desorption, XPS and TEM. The catalytic tests and characterization data confirmed that the sample of Ru/Modified-Vermiculite can be taken as a robust and effective catalyst for the conversion of the LA to GVL.

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The modified vermiculite supported-Ru catalyst has super activity and stability in the hydrogenation of levulinic acid to γ-valerolactone. Ru active components dispersed uniformly on the surface of organic modified vermiculite, and there was no obvious aggregation of the components. Even after fourteen cycles, levulinic acid conversion and γ-valerolactone selectivity remained 95% and 100%, respectively. The present work provides an efficient route for the preparing the Ru-based catalyst of excellent stability in the process of hydrogenation of levulinic acid.

C6 hydrocarbon (n-hexane, cyclohexane and 1-hexene) co-cracking over HZSM-5 zeolites at 320–550 °C were studied in this work to get an insight into the catalytic cracking process, which played an important role in the petrochemical industry. The total conversion was in an order of 1-hexene > n-hexane/1-hexene > n-hexane > n-hexane/cyclohexane > cyclohexane, and the conversion reduction with the prolonged reaction time was in an order of 1-hexene < n-hexane/1-hexene, n-hexane < n-hexane/cyclohexane < cyclohexane. It was deduced that the presence of 1-hexene promoted the total conversion and alleviated the conversion reduction in the co-cracking, while the presence of cyclohexane reduced the total conversion and accelerated the conversion reduction with the prolonged reaction time. In addition, increasing reaction temperature and 1-hexene content promoted ethene and propene selectivity in the co-cracking. The conversion and product distribution in the co-cracking can be attributed to the unique interaction of C6 molecular structure. The six-member ring of cyclohexane hindered the diffusion process, and thus inhibited n-hexane decomposition in the co-cracking. The C = C bond of 1-hexene was easy to interact with and occupied the acid site and carbenium ions, which inhibited n-hexane decomposition while promoted the durability of n-hexane decomposition against high coke content.

Ni/SAPO-11 catalysts with highly dispersed Ni (TA-Ni/SA-11) were prepared using tartaric acid as a dispersant. The effect of the tartaric acid content on the physiochemical properties of the TA-Ni/SA-11 catalysts and their n-heptane hydroisomerization performance were investigated. TA-Ni/SA-11 exhibits smaller Ni particles and more Ni active sites in comparison to conventional Ni/SAPO-11 prepared via the impregnation method due to the interaction between tartaric acid and Ni²⁺. As the molar ratio of tartaric acid and Ni²⁺ (n_TA/n_Ni) increases, the number of Ni active sites in TA-Ni/SA-11 rises, while the surface area and relative crystallinity decrease because of the dealumination of SAPO-11. When n_TA/n_Ni is 0.75, 0.75TA-Ni/SA-11 presents the highest n-heptane conversion of 82.4% and isomer selectivity of 90.5%, as well as the lowest cracking selectivity of 9.0% at 380 °C, 1.5 MPa, 2 h^− 1, and a volume ratio of H₂ to n-heptane of 400 among these catalysts.

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