Applied Catalysis A: General最新文献

The current review offers a comprehensive analysis of the catalytic N-benzyl hydrogenolysis debenzylation reaction, encompassing an examination of the catalytic mechanism and kinetic characteristics. Among the various catalysts employed in C−N hydrolysis, the supported palladium catalyst stands out as the most frequently employed catalyst. This review thoroughly elucidates the utilization of palladium catalyst in N-benzyl catalytic hydrogenolysis, providing insights into its activity, selectivity, and stability concerning support materials, cocatalysts, solvents, and pH conditions. These findings yield valuable insights for optimizing catalyst design and reaction conditions. Additionally, we briefly introduce the applications of other metallic catalysts such as nickel and platinum in catalyzing N-benzyl hydrogenolysis reactions. This provides valuable guidance for advancing our understanding of the hydrogenolysis reaction mechanisms, enhancing catalyst performance, and developing novel catalytic agents.

The preparation of Hydrogen peroxide (H₂O₂) by electrochemical two-electron oxygen reduction reaction (2e^- ORR) and water oxidation reaction (2e^- WOR) is a highly desirable method that can be green, clean and safe. However, the sluggish reaction kinetics and poor 2e^- ORR and WOR selectivity severely limits scale-up applications. To resolve these challenges, research on cost-effective catalysts have been intensively explored, which have made great progress. Herein, we first introduced the fundamental chemistry and catalytic mechanism of ORR and WOR, including the possible reaction pathways, the binding modes of oxygen and water on the catalytic sites, and the energy-barrier diagrams of each stage of the reaction obtained by theoretical calculations. Then, the current progress of catalyst research for electrocatalytic synthesis of H₂O₂ is discussed. Among them, single-atom catalysts as well as molecular catalysts are the hot spots of current research. Single-atom catalysts can reduce the amount of precious or non-precious metals used, and maintain catalytic activity while reducing costs; meanwhile, molecular catalysts have the advantages of single reaction performance, high selectivity, and clear mechanism, which are easy to design and grasp. Finally, on the basis of previous studies, the remaining challenges and development prospects of the current research on electrocatalytic production of H₂O₂ are discussed, and suggestions are provided for the development of this field in the future.

This work studies the reaction mechanism and the role of CO₂ in ethane dehydrogenation to ethene over two types of Pt-Zn/ZSM-5 catalysts. The calculation results demonstrate that the Pt-Zn sites have different roles, and Zn₆Pt₁/ZSM-5 is more active than Pt₃Zn₁/ZSM-5 due to more efficient Pt-Zn sites for dehydrogenation with the assistance of framework O of ZSM-5. CO₂ reacts with H- species generated from ethane dehydrogenation and creates new and facile H-consuming routes, thus promoting the reaction. The positive effect of CO₂ is more significant over Zn₆Pt₁/ZSM-5 than Pt₃Zn₁/ZSM-5 owing to the largely reduced barrier of rate-limiting step. Zn₆Pt₁/ZSM-5 greatly suppresses the competitive side reaction of CO₂ with ethyl species, thus becoming a promising catalyst for ethene generation. This work deepens the mechanistic understanding of CO₂-assisted dehydrogenation of light alkanes over Pt-Zn/ZSM-5 catalysts and unravels the important role of CO₂, providing a useful reference for future catalyst design.

Ni stabilized over zirconia-alumina support (10Ni/10ZrAl), and further enhanced with gallium promotion, was examined for its efficacy in dry reforming of methane. 1–3 wt % gallium addition to the 10Ni/10ZrAl catalyst led to an even distribution of gallium throughout the catalyst, increased formation of NiO species that are easily reduced, and deposition of less graphitic carbon compared to an unpromoted catalyst. 10Ni2Ga/10ZrAl catalyst has least carbon deposition and highest H₂ yield (26 %) at 600 ^°C. Process optimization is performed over best catalyst, 10Ni2Ga/10ZrAl, by varying space velocity from 30,000 cm³ g⁻¹h⁻¹ to 48,000 cm³g⁻¹h⁻¹, reaction temperature from 550 °C to 800 °C, and CH₄/CO₂ from 0.5 to 1. A regression model equation is set as the function of factors, and the response as H₂ yield through research surface methodology under center composite design. The model predicted an optimal H₂ yield of 91.95 % which is closely validated by 90.09 % H₂ yield experimental at optimized conditions.

The one-pot CO₂ hydrogenation to lower olefins involves the integration of two catalytic reactions in a single reactor: the conversion of CO₂ into methanol (CTM) and its subsequent conversion into lower olefins (MTO). This approach requires two catalysts cooperating in the same reactor, posing different challenges in terms of synergies and interactions between the two active phases. In this work, we investigate the effect of process conditions and arrangements between In₂O₃-ZrO₂ (CTM catalyst) and SAPO-34 (MTO catalyst) on the lower olefins yield. We show that the distance between CTM and MTO active sites, studied by assessing different catalyst arrangements spanning from an intimate mixture obtained through mortar mixing to a complete segregation of the catalysts (i.e., consecutive beds), plays a key role in driving the products distribution. However, the thermodynamic equilibrium of the reverse water gas shift limits CO₂ conversion in the investigated conditions. Finally, we discuss the stability of the catalytic performances: the characterization of the spent samples after ∼400 h on stream indicated the deactivation of the catalytic materials in all investigated cases, with In sintering on the methanol catalyst, and SAPO-34 losing both P and Al due to hydrothermal aging; indications of In migration on SAPO-34 were also observed when the two catalyst are in contact.

Two types of 5 %wt Ru/AC catalysts were prepared using carbon carriers treated with 5 mol L⁻¹ HNO₃ and 5 mol L⁻¹ HCl by the impregnation method, respectively. The catalysts were characterized by N₂ physical adsorption, XRD, XPS, SEM, TEM and ICP-AES. The catalytic activity and stability of the catalysts for the decomposition of hydroxylamine nitrate (HAN) and hydrazine nitrate (HN) was evaluated. The results demonstrated that both catalysts exhibited complete decomposition of HAN and HN under moderate reaction conditions (70–90 ℃), displaying similar activities. And the catalysts treated with hydrochloric acid exhibited better stability and can be reused 128 cycles. Furthermore, the experimental results on various parameters indicate that an increase in temperature and nitric acid concentration leads to a reduction in reaction time. The catalytic performance of Ru/AC catalyst remains unchanged after 20 cycles under radioactive conditions, exhibiting exceptional radiation resistance.

Due to the expensive cost of precious metals, there is an urgent need to develop cheap and efficient catalysts for the oxygen evolution reaction (OER). As a novel catalyst, high-entropy alloy (HEA) has found widespread application in the field of hydrogen production through water electrolysis. However, a significant portion of HEA catalysts prepared by traditional solvothermal methods are challenging due to their high cost, extended compound cycle, and relatively difficult electronic structure adjustment in the catalytic center. In this study, a heterostructure catalyst composed of MoC and FeCoNiMo HEA alloy (denoted as FeCoNiMo-M) was synthesized by the microwave method. Catalysts produced via the microwave method typically exhibit MoC encloses the spherical heterostructure of the internal high entropy alloy, MoC not only protects the true active center NiOOH, but even further regulates the electronic structure of the catalyst. Notably, the FeCoNiMo-M sample synthesized using microwave demonstrates an overpotential of merely 232 mV (@10 mA cm⁻²) in 1 M KOH, nearly 20 mV lower compared to the traditional hydrothermally-synthesized FeCoNiMo-H HEA catalyst. Furthermore, the FeCoNiMo-M catalyst demonstrates impressive durability in OER with a significant current density of 100 mA cm⁻² for a duration of 240 hours. The in-situ Raman results indicate that the FeCoNiMo-M catalyst undergoes the conversion of the actual reaction intermediate NiOOH and accelerates the OER with only a very low overpotential. These findings suggest that our approach could open up possibilities for the advancement of OER catalysts that are both more convenient and efficient.

Semiconductor photocatalysis technology has a wide range of application in the treatment of environmental pollution. In this study, the Z-scheme heterojunction photocatalyst ZIF-8/Bi₄O₅Br₂ was synthesized by hydrothermal method. The morphology, structure, mechanism and photocatalytic performance of the materials were studied. Under simulated sunlight illumination for 60 minutes, the degradation efficiency of oxytetracycline (15 mg·L⁻¹) reached 94.2 %. In light of density functional theory calculation and liquid chromatography-mass spectrometry, the attack sites and degradation pathways of OTC were determined. The consequence of free radical capture test and electron paramagnetic resonance detection showed that ·O^2-, ·OH and h⁺ were the primary active substances. Based on the analysis above, the charge transfer principle of Z-scheme heterojunction was further elucidation. It inhibited the recombination of photo carriers and improved the photocatalytic performance. This work provides a hopeful measure for photocatalytic degradation of OTC by Z-scheme heterojunction composite.

Heterogeneous oxide couplers represent a type of emerging composite materials with inherently outstanding interface properties for electrocatalytic applications. In this study, we fabricate a Ru-Co nano-oxide coupler that enables internal electron transfer between Ru and Co elements. The catalyst exhibits superior oxygen evolution reaction (OER) performance compared to commercial RuO₂, with mere 260 mV overpotential at 10 mA cm⁻². The exchange current density (i₀) for RuO_2/Co₃O₄ is enhanced by three orders of magnitude compared to commercial RuO₂. Electrochemical characterizations and computational analysis reveal that the coupling of Co₃O₄ and RuO₂ enhances the surface's capability for water dissociation on the interface Ru sites, thereby initiating OER. The exceptional performance of RuO₂/Co₃O₄ enables water splitting via a single-cell AA battery configuration that utilizes a RuO₂/Co₃O₄ anode || Pt/C cathode setup. This accomplishment underscores the potential of RuO₂/Co₃O₄ for effective and sustainable electrochemical water splitting applications.

The Pt-based alloys catalysts with special morphology attract great attention. Herein, a flocculent-structured high-entropy-alloy (HEA) (named as F-PtBiCuCoMo/C) electrocatalyst is prepared by co-reduction, which can greatly improve the overall catalytic performance and reduce Pt-usage. In ethylene glycol oxidation reaction (EGOR), it has mass activity of 1.08 A mg⁻¹_Pt, which also has a good durability with high residual current density (0.27 A mg⁻¹_Pt after 3000 s). Notably, the power density reached 17.9 mW cm⁻² in as-assembled direct ethylene glycol fuel cells (DEGFC), which exceeded commercial Pt/C references by 2.4 times. Thence, this F-PtBiCuCoMo/C electrocatalyst would be a good option for the advancement of DEGFC technology.