Applied Catalysis A: General最新文献

In the semi-hydrogenation of acetylene, nickel-based catalysts offer a promising alternative to precious metal palladium catalysts. Despite the positive hydrogenation activity of nickel-based catalysts, there is still room for improvement in terms of their selectivity and stability. In this study, a simple incipient wetness impregnation method was employed to prepare Ni(OAC)₂-IL/Al₂O₃ catalyst and its performance in the selective hydrogenation of acetylene was investigated. It was found that under the conditions of 170 °C and a space velocity of 600 h⁻¹, the 3 % Ni(OAC)₂-IL/Al₂O₃ catalyst achieved a 95.3 % acetylene conversion with an 85.6 % ethylene selectivity. Furthermore, the catalyst exhibited outstanding stability over a 100 hour test. TEM, XPS and C₂H₄-TPD experiments showed that the Ni species were encapsulated in the ionic liquids (ILs), and the interaction between the metal ions, nickel, and the ILs ensured a high dispersion and stability of the actives on the carriers, and the electronic effect between the ionic nickel and the ionic liquids increased the electron cloud density of the Ni, which improved the catalyst selectivity, which is the main reason for its excellent catalytic performance.

The catalytic and electrochemical hydrogenation of CO₂ offers the option of a carbon-neutral cycle for sustainable energy and synthesis of value-added chemicals. The synthesized noble metal-free Cu-InO₂@rGO nanocomposite has been characterized by various techniques such as scanning electron microscopy (SEM) confirming the spherical shape of Cu-InO₂ nanoalloy embedded on rGO, the average size calculated by high resolution-transmission electron microscopy (HR-TEM) shows Cu-InO₂ (∼ 4 nm) alloy is on rGO surface (∼100 nm). The XRD pattern confirms the Face centered cubic (FCC) crystal structure of Cu-InO₂@rGO, and Furrier transform- Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses of Cu-In-O exist in the nanomaterials. The linear sweep voltammetry (LSV) demonstrates an ultra-low potential of −0.9 V vs. SCE. The bulk electrolysis on Cu-InO₂@rGO electrocatalyst demonstrated at a potential of −1.1 V vs. SCE to reach HCOOH with a Faradic yield of 76.10%. Electrochemical CO₂ reduction on Cu-InO₂@rGO is responsible for the variation of adsorption of CO₂ intermediates due to controlled selectivity and inhibiting the formation of H₂ and CO. In catalytic hydrogenation used as the same catalyst was found, an excellent yield towards HCOOH is 5.5 mmol. Current studies have highlighted the enhancement in activity along with selectivity for product formation could be due to having a capable active interface from electrocatalysts for low cost and proficient production of fuels.

MIL-125(Ti) is well known for having stable structure, tunable electron structure, and multiple active sites, which is commonly studied in the field of photocatalysis. In this work, a series of rare earth (RE) doped MIL-125(Ti) (RE=Ce, Pr, Tm, Dy, Eu, and Sm) are prepared via the one-step hydrothermal method. Notably, Pr-MIL-125 displays a significantly enhanced catalytic performance than other RE-doped MIL-125, resulting in a maximal CO and CH₄ yield of 13.30 and 0.87 µmol·g⁻¹·h⁻¹, respectively, which are 2.53-fold and 4.14-fold of the pristine MIL-125. The layered morphology endows Pr-MIL-125 with more active sites and facilitates the reaction of photoreduction CO₂. Furthermore, the promoted photoactivities attributed to Pr ion dopant can act as electron transfer bridge and suppress charge recombination. This work would provide insight and guidance for designing RE-MOF based photocatalysts and enhancing the performance of photoreduction CO₂.

High-entropy oxides (HEOs) have garnered significant attention in catalysis due to their excellent redox properties and superior stability. In this study, we prepared and investigated a high-entropy oxide, Cu₁Zn₁Al_0.5Ce₅Zr_0.5O_x, to elucidate the impact of oxygen vacancy density on the CO₂ hydrogenation reaction. Comparisons were made with binary or ternary solid solutions composed of the same cations present in this HEO, and possessing the same phase structure. The HEO exhibits a higher surface oxygen vacancy density as evidenced by Raman spectroscopy and XPS. The increased number of oxygen vacancies significantly increases the active sites and enhances the strength for CO₂ adsorption. Combined with kinetic analysis, it is suggested that the enhanced CO₂ adsorption leads to improved CO₂ conversion on the HEO. Moreover, the formation of oxygen vacancies facilitates H₂ dissociation and supply, which is pivotal for methanol formation on the HEO. The stability of the HEO Cu₁Zn₁Al_0.5Ce₅Zr_0.5O_x surpasses that of the medium entropy oxide, showing no significant deactivation after 100 hours of reaction.

The introduction of oxygen vacancies (OVs) into photocatalysts has proven to be a successful tactic to boost CO₂ reduction. However, the challenge lies in acquiring OV sites that are stable in the long term, highly dispersed, and tunable in concentration. Herein, an innovative configuration, referred to as N-Bi^(3+x)+--O_V, was developed for the model semiconductor Bi₂O₂CO₃ via an in situ anion doping approach. The structure enables the synthetic photocatalyst to exhibit superb CO₂ photoreduction performance, with approximately 100% CO selectivity and remarkable long-term stability. Experimental studies and density functional theory (DFT) calculations show that replacing O^2- with N^3- uniformly in the [Bi₂O₂]²⁺ structural unit increases the chemical valence of Bi, elongates nearby Bi─O bonds, releases lattice O, improves CO₂ absorption, and decreases the energy barrier for the formation of the critical intermediate *COOH. This study offers new insights and potential opportunities for the development of reliable defect-type semiconductors and their catalytic applications.

BaTaO₂N (BTON) with a generous adsorption edge of ca. 660 nm and high theoretical solar-to-hydrogen conversion efficiency of ca. 20.6% has been extensively investigated for photocatalytic water splitting. In this study, we have successfully prepared a porous BTON nanosheet via employing Ba₂Bi₃Ta₂O₁₁Cl (BBTOC) oxyhalide as a novel nitridation precursor. The oxygen evolution rate of the BTON nanosheet is 108 μmol·h⁻¹, which is three times higher than that of BTON (25.9 μmol·h⁻¹) prepared by conventional solid-state method. The successful construction of porous BTON nanosheet is due to the structural transformation of BBTOC nanosheet precursor and facile evaporation of Bi and Cl elements. The porous nanosheet morphology of BTON can not only promote the transfer of photogenerated charge carriers but also provide abundant reaction sites for the oxygen evolution reaction. This work demonstrates a novel and efficient strategy for preparing oxynitride for efficient solar energy conversion.

The geometric and electronic structure of Pt active sites plays a crucial role in determining the catalysts performance, but precise regulation remains challenging. Herein, we propose a novel approach to modulate the nature of Pt active sites by combining photo-deposition of Pt nanoparticles with ultra-low Mo loading (0.1 wt%) modification on Pt/SiO₂ catalysts. The addition of ultra-low loading Mo promoter not only effectively reduces the size of Pt particles but also donates electrons to the Pt particles. Furthermore, the photo-deposited Pt particles exhibit a higher proportion of metallic Pt species, which is more stable than that metallic Pt species obtained by H₂ reduction, compared to those prepared using traditional wetness impregnation methods. Propane oxidation activity evaluations confirm that the photo-deposited and Mo-modified Pt/0.1Mo/SiO₂-P catalyst exhibits the highest activity among all the prepared catalysts. Combined with experiments of C₃H₈-TPSR and in-situ DRIFT spectra of propane oxidation, it is found that the Pt/0.1Mo/SiO₂-P catalyst remarkably promotes propane activation and C-H bond cleavage due to the nature change of Pt active sites, and the presence of gaseous oxygen benefits propane cleavage on active sites. Our primary results provide a promising strategy for designing superior platinum catalysts by regulating Pt active sites nature for efficient propane complete oxidation.

Metal-organic framework (MOF)-derived hollow metal oxides exhibit significant potential as cutting-edge electrocatalysts for the oxygen evolution reaction (OER) owing to their exceptional intrinsic activity, expansive specific surface area, structured controllability, and adjustable pore dimensions. Nevertheless, their industrial utilization faces the obstacles such as intricate synthesis procedures, limited scalability, and inconsistent performance, necessitating the formulation of effective solutions. Various engineering strategies have been proposed by researchers to tackle these hurdles. This comprehensive review highlights recent breakthroughs in engineering MOF-derived hollow metal oxides and their applications in electrocatalytic OER. It initiates by juxtaposing the drawbacks of traditional metal oxides against the advantages of MOF-derived hollow metal oxides. Subsequently, it delves into a thorough exploration of the engineering methodologies employed to elevate their OER efficiency. Lastly, the review delineates current challenges and potential avenues for the development of more efficient MOF-derived hollow metal oxide electrocatalysts in the future.

Hydroconversion of guaiacol (GUA) over γ-Al₂O₃ and phosphatized-γ-Al₂O₃ (γ-Al₂O₃(P)) supported Ni catalysts was initiated by Lewis-sites and active Ni sites. Conversion proceeded via transmethylation and hydrodemethylation/hydrodemethoxylation as major and minor pathways, respectively, resulting in mainly catechol and methylcatechols, and via series of consecutive hydrodehydroxylation (HDHY) and ring hydrogenation (HYD) reactions leading to partially and fully deoxygenated, saturated, and unsaturated products. High Ni-loading and high H₂ pressure promoted the formation of cyclohexane and methyl-substituted cyclohexanes; however, above 300 °C the hydrogenation–dehydrogenation equilibrium favored the formation of benzene and methyl-substituted benzenes. Ni/γ-Al₂O₃(P) showed suppressed HYD/HDHY activity resulting in pronounced formation of catechol and/or phenol and their methyl-substituted derivatives. Surface phenolate species were substantiated as surface intermediates of hydrodeoxygenation. Phosphatizing reduced the concentration of both basic OH and Lewis acid (Al⁺) – Lewis base (O^–) pair surface sites of the γ-Al₂O₃ support and, thereby, suppressed phenolate formation and hydrodeoxgenation.

In this study, we report an efficient, stable, and renewable N, P co-doped coffee biochar-based catalyst loaded with highly dispersed Ni-N_x species (Ni/NPCB-600), and it was successfully applied to the aqueous-phase chemoselective reduction or reductive amination of diverse nitroarenes (Yield up to >91%). Experimental and characterization studies revealed that N, P co-doping have a synergistic effect on improving the catalytic performance of Ni/NPCB-600. The textural properties of Ni/NPCB-600 are enhanced after doping of P, which can facilitate mass transfer and expose more accessible active sites in the reaction. The doping of N could induce the formation of Ni-N_x sites and enhance the basicity of the Ni/NPCB-600 catalyst, which can promote the adsorption and activation of formic acid and nitroarenes, respectively. This is the first example of N, P co-doped coffee biochar-based catalyst for nitroarenes reduction or reductive amination, and reveals its potential industrial application prospects.