Catalysis Science & Technology最新文献

The electrochemical reduction of CO₂ (CO₂RR) offers a promising route for sustainable fuel and chemical production. This study compares the CO₂RR performance of hydrothermally synthesized carbon nanosphere-supported nickel hydroxide (Ni–C), copper hydroxide (Cu–C), and bimetallic nickel–copper hydroxide (NiCu–C) catalysts, investigating the influence of metal composition. Significant differences in product selectivity were observed: Cu–C primarily yielded C₂ products, whereas Ni–C and NiCu–C generated mixtures of H₂, CO, formate, and acetate, with minimal C₃ products. Faradaic efficiencies (FEs) for C₃ products (including propylene, propane, and n-propanol) were very low for Ni–C and NiCu–C (<0.3% combined). In comparison, Cu–C showed modest FEs (∼3–5%) primarily for n-propanol. X-ray photoelectron spectroscopy revealed partially oxidized nickel species (Ni^δ+) in Ni–C and NiCu–C and predominantly Cu(I) species post-reaction, while scanning electron microscopy confirmed a distinct fibrous morphology for the Ni-containing catalysts. Control experiments with CO and acetate, and in situ Raman spectroscopy, suggest reaction pathways that differ from the typical Cu-catalyzed routes, potentially involving hydrogenated intermediates such as *CHO. This work provides a comparative analysis, highlighting how catalyst composition and associated electronic/structural properties influence the overall CO₂RR activity and selectivity pathways in Ni, Cu, and NiCu hydroxide systems, rather than achieving significant C₃ production.

IrRu nanoparticles surrounded by Ir/Ru–N–C retain 91.68% of the initial current density at 0.1 V vs. RHE toward acidic hydrogen oxidation reaction in the presence of 1000 ppm CO/H₂, closely correlated with the removal of CO via the following reaction: CO_ad–IrRu nanoparticle + OH_ad–Ir/Ru–N–C → COOH_ad.

During the methanol-to-propylene (MTP) process, the catalytic performance of zeolite catalysts is closely related to its pore structure and acid property. Exploring the structure–function relationship is of great significance for both academic research and industrial applications. In the present work, a series of hierarchical ZSM-11 zeolites with different SiO₂/Al₂O₃ ratios were synthesized by changing the chemical composition of gel precursors. XRD, SEM, TEM, N₂ adsorption–desorption, NH₃-TPD, ICP-OES, NMR spectroscopy, FT-IR spectroscopy, pyridine-IR spectroscopy, in situ UV/vis spectroscopy and TG-DTG analysis were used to explore the structural and textural properties of the as-synthesized zeolite samples. The results show that the change in the SiO₂/Al₂O₃ ratio in the gel precursors has some effects on the morphology, crystalline sizes and porous structural properties of the samples. Furthermore, it plays an important role in tailoring the distribution of the framework Al species and thus in adjusting the acid sites of the as-prepared ZSM-11 catalysts. The distribution of framework Al species in the intersecting cavity significantly decreases with the increased SiO₂/Al₂O₃ ratio in the gel precursors, which inhibits the reaction paths based on the aromatic cycle, resulting in a reduction of aromatic products and carbon deposition precursors while enhancing the selectivity of the targeted product propylene. Typically, as compared with the low-silicon ZSM-11-60, the relatively high-silica ZSM-11-160 exhibits superior catalytic performance to achieve a high selectivity of propylene in the final products (39.4% vs. 17.6%) and a longer catalytic life (106 h vs. 42 h) because of a low coking deposition rate (0.52 mg g⁻¹ h⁻¹vs. 2.21 mg g⁻¹ h⁻¹) during the MTP process.

A series of Ru–Mn catalysts supported on desilicated ZSM-5 (RuMn/ZS) are prepared and investigated for the oxidation of HMF to FDCA under aqueous conditions without an external base. RuMn/ZS shows a two-fold higher catalytic activity than Ru–Mn supported on the parent ZSM-5 (RuMn/HZ), giving the highest FDCA yield of 76.7% under optimised reaction conditions. N₂-sorption analysis indicates that RuMn/ZS possesses a 1.22 times higher total surface area (448 m² g⁻¹) and 2.72 and 6.72 times higher mesopore surface area (207 m² g⁻¹) and mesopore volume (0.942 cm³ g⁻¹) than the parent RuMn/HZ due to the desilication. High-resolution transmission electron microscopy (HRTEM) and elemental mapping indicate that RuMn/ZS possesses relatively smaller particle sizes (1.7 nm) with high dispersion of Ru and Mn. NH₃ and CO₂-temperature programmed desorption studies show that RuMn/ZS has a 2 times higher amount of total acidic sites and a 1.79 times higher amount of total basic sites compared to RuMn/HZ. In addition, RuMn/ZS also possesses a balance ratio of acidic to basic sites (3.08) with optimal amounts compared to other catalysts employed in this study. Furthermore, an in situ diffuse reflectance infrared Fourier transform (DRIFT) study using ammonia, pyridine, and CO₂ as probe molecules discloses that RuMn/ZS possesses relatively stronger Lewis acidic sites and stronger basic sites than RuMn/HZ. HMF adsorbed RuMn/ZS diffuse reflectance ultraviolet-visible and DRIFT spectra substantiate the stronger Lewis acidity and basicity than those of RuMn/HZ. Poisoning studies with additives, such as KSCN, further substantiate the crucial primary role of Lewis acidic sites in efficiently catalysing the HMF oxidation reaction. RuMn/ZS is recyclable for three runs with no notable activity loss.

The integration of adsorption and photocatalysis in heterojunction composites offers a promising strategy for efficient azo dye degradation. Here, a novel α-Fe₂O₃/perylene-3,4,9,10-tetracarboxylic diimide (PDINH) Z-scheme heterojunction was synthesized via a facile solvent method, showcasing synergistic adsorption–photocatalysis for wastewater treatment. Zeta potential analysis (α-Fe₂O₃: +14.7 mV; PDINH: −24.3 mV at pH 5.0) and density functional theory (DFT) calculations (binding energy: −3.10 eV) revealed strong electrostatic interactions between α-Fe₂O₃ and PDINH, enabling uniform nanoparticle dispersion and forming a heterostructure with enhanced specific surface area. Electrochemical measurements confirmed that the Z-scheme heterojunction significantly accelerated charge carrier migration and suppressed electron–hole recombination, facilitated by an internal electric field from well-matched band alignment. Under visible light, the α-Fe₂O₃-15/PDINH composite achieved 93.4% removal of methyl orange (MO), outperforming PDINH alone (63.1%) due to its positive surface charge (+8.7 mV at pH 5.0) that enhanced selective adsorption of anionic dyes. Quenching experiments identified h⁺, ·O₂⁻, and ·OH as the primary reactive species, with the Z-scheme pathway retaining strong redox capabilities for efficient degradation. Notably, the composite exhibited an operational cost of $2.41 per ton, significantly lower than other reported processes, and maintained high efficiency (81.8% MO removal) over multiple cycles. This work demonstrates that the α-Fe₂O₃/PDINH composite integrates adsorption and photocatalysis synergistically, providing a low-cost, scalable solution for azo dye wastewater treatment with potential for industrial application.

Chromium complexes supported by alkyl-bridged PCCP ligands (Ph₂PCH(R¹)-C(R²)PPh₂) demonstrate exceptional catalytic activity and selectivity in ethylene tri-/tetramerization reactions. To elucidate the influence of PCCP ligand geometry on catalytic performance, a series of bisphosphine ligands featuring five- to eight-membered cycloalkane bridges were systematically synthesized. Notably, the catalytic behavior is profoundly dependent on the ring size of the cycloalkane bridge. As the bridge cycloalkane increases in ring size, the chromium complexes exhibit a 3.4 fold enhancement in activity (from 813 kg g⁻¹ Cr per h for the five-membered ring to 2891 kg g⁻¹ Cr per h for the eight-membered variant) alongside a progressive improvement in α-olefin selectivity (total selectivity of 1-C₆ and 1-C₈ from 76.5% to 90.3%). Concurrently, polyethylene formation is dramatically suppressed (from 38.6% to 0.14%). Under optimal conditions, complex bearing ligand 4 achieves a peak activity of 3120 kg g⁻¹ Cr per h with 48.9% 1-C₈ selectivity, 89.9% α-olefin selectivity, and near-complete suppression of polymer. Structural analysis reveals a critical correlation between the ligand backbone dihedral angle and catalytic performance: smaller dihedral angles correlate with higher activity, underscoring the pivotal role of ligand structure in tuning reactivity.

The extensive use of plastics has resulted in severe environmental pollution, making the valorization of plastic waste not only a strategy for value recovery but also an effective approach to mitigate its environmental impact. Consequently, this topic has become a focal point of research in industry and academia. Pyrolysis is a key step in the carbon resource conversion of plastic waste, facilitating the degradation of complex polymeric materials into high value products such as alkanes, olefins, and BTX. This review summarizes recent advancements in plastic pyrolysis technologies, as a focus on scientific challenges and technological breakthroughs in this domain. Through a systematic analysis, the study examines the pyrolysis mechanisms and current research status of the most widely used plastics, exploring the critical factors influencing the pyrolysis process including reaction conditions, such as temperature, residence time, and catalyst dosage, and the reactor design which has a significant role in improving the pyrolysis efficiency and product selection. This review provides a summary of commonly used catalyst types, with emphasis on the exceptional performance of zeolite based catalysts and their metal modified productions. Research indicates that zeolite catalysts, owing to their strong acidity and stable pore structures, markedly enhance the activity and selectivity of pyrolysis reactions. Other catalysts such as FCC catalysts, clay catalysts and metal oxides have shown promising catalytic performance under certain conditions, offering potential for the industrial applicability of plastic pyrolysis technologies. However, plastic waste pyrolysis research remains a challenge, including regulation of reaction pathways for co-pyrolysis of multi-component plastics, reducing catalyst deactivation, and optimization of energy efficiency. These challenges not only limit further promotion of pyrolysis technologies but also demand more fundamental scientific research and engineering advances. Finally, we conclude with future research directions, with suggestions for theoretical guidance and technology support for plastic waste pyrolysis development and industrial applications.

High-efficiency, robust and low-cost electrocatalysts for the oxygen reduction reaction (ORR) are at the heart of new energy conversion and storage devices. Recently, atomically dispersed metal electrocatalysts (metal–nitrogen–carbon, M–N–C) for the ORR have received great attention. Herein, this review presents recent advances in the noble metal-free atomically dispersed metal electrocatalysts toward the ORR. Specifically, we first introduce the different mechanisms of 2e⁻ and 4e⁻ ORR on the catalyst. Then, the classification and corresponding recent advances in M–N–C electrocatalysts are reviewed, including metal coordination configuration (like the structure and coordination of N in M–N₄, heteroatom substitution, heteroatom doping in carbon skeleton and axial coordination), modulation of the second atom in diatomic catalysts, and the effect of metal nanoparticles/clusters in M–N–C catalysts. In parallel, the synthesis strategy, structure, electrochemical properties and reaction mechanism are highlighted. Finally, an outlook on the current advances and challenges and the potential of the M–N–C-based electrocatalysts towards 2e⁻ and 4e⁻ ORR are discussed.

In this study, we disclose a Zn(II)-catalysed metal-ligand cooperative approach that converts renewable primary alcohols into highly substituted N-heterocycles via acceptor-less dehydrogenation. A well-defined Zn(II) complex, C1, supported by the NNN pincer ligand (E)-2-((2-(pyridin-2-yl)hydrazineylidene)methyl)pyridine (L1), was prepared and characterized by IR, UV-vis, ¹H and ¹³C NMR spectroscopy, HRMS, and single-crystal X-ray diffraction. Complex C1 efficiently promotes a one-pot, three-component synthesis of 1,3,5-trisubstituted-pyrazolines from aromatic primary alcohols, aromatic ketones, and phenylhydrazine. The scope of C1 was further demonstrated in the multicomponent construction of 2,4,5,6-tetrasubstituted pyrimidines from primary alcohols, challenging cyclic ketones, and various amidine hydrochlorides, as well as in the dehydrogenative coupling of 2-aminobenzyl alcohol with aromatic ketones to furnish quinolines. Overall, 30 pyrazolines, 42 pyrimidines, and 27 quinolines were obtained in good yields. Control experiments, HRMS study, and DFT calculations collectively support a reaction pathway in which alcohol dehydrogenation proceeds through a metal–ligand cooperative mechanism.

PdZn_β alloy catalysts have attracted extensive attention in the methanol steam reforming (MSR) reaction due to their superior thermal stability compared to Cu-based catalysts, which are prone to sintering. However, conventional supported PdZn catalysts typically require a high Pd loading (e.g., Pd/ZnO, >5.0 wt%) to achieve the desired MSR performance, limiting their practical applications. In this work, we explore a ZnTiO₃ perovskite as a support and a zinc source to achieve the controlled synthesis of the PdZn_β alloy at low Pd loadings. The 0.1 wt% Pd/ZnTiO₃ catalyst achieves excellent reactivity and CO₂ selectivity (>96%) across a wide temperature range (up to 400 °C). This performance is attributed to the enhanced synergy between the small PdZn_β particles and the ZnTiO₃ support, which enhances methanol dehydrogenation and water dissociation, respectively. The catalyst also shows exceptional thermal stability over 50 hours at 350 °C with minimal loss in activity or selectivity, while pure ZnTiO₃ deactivates significantly. The advanced Pd/ZnTiO₃ catalysts with ultra-low Pd loading demonstrate superior potential over other metal oxides for efficient and stable hydrogen production in mobile applications, which typically need to operate at high reaction temperatures.