Hierarchical Catalysts Research Articles

Gel–sol synthesis of hierarchical CaO using pollen as biotemplate for biodiesel production

In this paper, a novel hierarchical calcium-based catalyst marked as CaO(S) has been established to catalyze oil-methyl acetate-methanol for no-glycerol biodiesel production. The CaO(S) was synthesized through sol–gel-biotemplate method using calcium nitrate-ethanol-citric acid as precursor and rape pollen as biotemplate, followed by the characterizations such as N2-Brunauer Emmet Teller (N2-BET), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), CO2-temperature programmed desorption (CO2-TPD), Thermogravimetry differential thermal analysis (TG-DTA) and scanning electron microscopy (SEM). The results indicate that pollen as a biotemplate could be used to improve the basicity and textural parameters of calcium oxide particles, especially for 1/1-CaO(S)-700, presented by its total basicity of 5.90 mmol/g, the specific surface area of 16.47 m2/g, the pore volume of 0.04 cm3/g, the average pore size of 10.28 nm, and the widespread distribution of pore size (2–12.5 nm). Moreover, the yield of no-glycerol biodiesel, 96.62%, has been investigated after 3 h under optimized conditions (temperature = 65 °C, dosage of CaO(S) = 10 wt%, oil/methyl acetate/methanol = 1/1/8), by the yield presence of 91.37% after 3 cycles, which indicated that the 1/1-CaO(S)-700 prepared by sol–gel-biotemplate method had good stability.

Electrochemically reconstructed ternary active sites of hierarchical hollow Co-based catalyst for enhancing oxygen evolution reaction

Electrochemically reconstructed ternary active sites of hierarchical hollow Co-based catalyst for enhancing oxygen evolution reaction

Tree-like hierarchical porous anode catalyst layer for efficient proton exchange membrane water electrolyzer by optimization of transportation

Tree-like hierarchical porous anode catalyst layer for efficient proton exchange membrane water electrolyzer by optimization of transportation

Macro-micro structure controlled hierarchical porous copper catalysts via laser powder bed fusion and chemical dealloying of a FeCoNiCu high-entropy alloy

Macro-micro structure controlled hierarchical porous copper catalysts via laser powder bed fusion and chemical dealloying of a FeCoNiCu high-entropy alloy

Outstanding Formaldehyde Abatement Performance and Preferable Resistance to SO2 and H2O over CrOx-CeOx Facilitated Hierarchical Porous Biochars Catalysts

Outstanding Formaldehyde Abatement Performance and Preferable Resistance to SO2 and H2O over CrOx-CeOx Facilitated Hierarchical Porous Biochars Catalysts

Hierarchical assembly of Pt single atoms and WC nanocrystals on porous carbon Boosting hydrogen evolution reactions.

Hierarchical assembly of Pt single atoms and WC nanocrystals on porous carbon Boosting hydrogen evolution reactions.

Hierarchical Malachite Microsphere Catalyst in the Ethynylation of Formaldehyde for 1,4-Butynediol Synthesis.

The challenge of improving the wear resistance of Cu-Bi catalysts continues to persist in the industrial production of 1,4-butynediol (BYD) through the ethynylation of a formaldehyde reaction. Herein, We successfully prepared a hierarchical malachite microsphere catalyst by cooling the crystallization process under atmospheric pressure. The hierarchical malachite microspheres are uniform spheres with a diameter of 18 μm, which are composed of numerous two-dimensional microplatelets paralleling the sphere surface. The cooling rate is a crucial factor that significantly influences the development of the crystal morphologies. A slower cooling rate enhances the crystallinity of the catalyst particles, leading to the formation of larger microplatelets on the catalyst surface. Experimental results demonstrated that the spherical malachite catalyst, synthesized via the cooling crystallization method, exhibits excellent wear resistance and sustained catalytic performance in the ethynylation of formaldehyde for the synthesis of BYD.

Large-Scale Preparation of Granular Sludge@MOF-Derived Hierarchical Porous Carbon Catalysts for Advanced Oxidation Process: Preparation Process and Intrinsic Degradation Mechanism

Tetracycline (TTCH) is widely used but difficult to remove, which poses a threat to the health of the ecosystem, so it is urgent to take effective measures to remove it. Granular sludge plays an important role in biochemical treatment. Its rich functional groups and loose porous structure make it a potential catalyst carrier. This study utilized granular sludge as a precursor and modified it by loading a Zn/Co-zeolite imidazolate framework (ZIF-67/8). After carbonization, a granular sludge-supported MOF-derived porous carbon material (GSZC-800) with high catalytic activity is produced. The degradation rate of tetracycline reached a maximum of 90.8% after 40 min of reaction, and the optimal conditions were 20 ppm of initial pollutant concentration, 0.05 g/L of catalyst, and 0.10 g/L of peroxymonosulfate (PMS), which is superior to biomass-charcoal derived catalysts that have been reported in the literature. Through ion interference experiments, radical quenching experiments, electron transfer mechanism studies, and fluorescence spectroscopy analysis, it is suggested that this is a non-radical mechanism dominated by a single linear oxygen species. The catalyst GSZC-800 exhibits an ease of preparation and accessibility, has a wide range of applicable pH values, and effectively removes different pollutants. It has potential applications in treating actual wastewater and various pollutants. This study not only provides a new idea for the high-value utilization of granular sludge, but also provides an important theoretical and experimental basis for the development of efficient and stable non-homogeneous catalysts.

Enhancing peroxymonosulfate activation with hierarchical cobalt-based N-doped carbon catalysts derived from hybrid MOFs intermediates for tetracycline degradation: Performance, mechanism insights and biotoxicity evaluation

Enhancing peroxymonosulfate activation with hierarchical cobalt-based N-doped carbon catalysts derived from hybrid MOFs intermediates for tetracycline degradation: Performance, mechanism insights and biotoxicity evaluation

Influence of metal doping on the coke formation of a novel hierarchical HZSM-5 zeolite catalyst in the conversion of 1-propanol to fuel blendstock.

In this work, the effect of Ni doping on coke formation and the activity of a novel hierarchical HZSM-5 zeolite catalyst in the conversion of 1-propanol to fuel blends was investigated. The catalysts, which were hydrothermally synthesised and modified with 0.5 wt% Ni, were characterised using different techniques (XRD, FTIR, SEM, PSD, N2 adsorption, NH3-TPD, TGA-DTA) and tested at 350-400 °C and, WHSV of 7 and 12 h-1 for the conversion of 1-propanol into fuel blendstocks. The catalyst characterisation results confirmed the successful synthesis of hierarchical HZSM-5 and the incorporation of nickel. The catalytic results showed that both catalysts exhibited >98% 1-propanol conversion with considerable selectivity (>80%) for jet fuel and (>50%) gasoline blendstock. While Ni/HZSM-5 favoured jet fuel, the undoped catalyst improved gasoline production. The stability and deactivation study showed that HZSM-5 exhibited greater long-term stability and maintained a conversion rate of >95%, making it well-suited for the extended conversion of 1-propanol. The moderate production of jet fuel and the uniform selectivity of gasoline indicate a balanced distribution of products. In contrast, Ni/HZSM-5 initially provides higher jet fuel production and stable gasoline production, but the conversion rate drops more sharply after 40 h on stream, which is due to rapid deactivation by coke accumulation or deactivation of metal sites. The coking study showed that the Ni-doped catalysts produced more coke, resulting in a weight loss of 6.4 wt% compared to the unmodified catalysts (6.1 wt%), which contributed to their deactivation, as evidenced by a reduction in 1-propanol conversion. Characteristic spectral bands from the analysis of the spent catalysts indicated the composition of the coke present, with key regions at 1300-1700 cm-1 and 2800-3100 cm-1 showing that the spent catalysts consisted of polycondensed aromatics, conjugated olefins and aliphatics. It can be concluded that the metal modification improves the catalytic performance but increases the coking and deactivation tendencies compared to the unmodified catalyst, which may limit the stability of the catalyst.

Preparation of high stability hierarchical bimetallic Ni-Mo catalysts for CO2 reforming with methane

Preparation of high stability hierarchical bimetallic Ni-Mo catalysts for CO2 reforming with methane

Regulating Carbon Vacancies and Undercoordinated Mo Sites in Mo2C Catalysts Toward Photo-Thermal Catalytic Conversion of Biomass Into H2 Fuel.

The conversion of biomass into chemical fuels is exciting but quite challenging in the development of an effective conversion strategy to generate easily-separated products without energy consumption. Herein, a lignocellulosic biomass-to-H2 conversion system via photo-thermal catalysis over Mo2C hierarchical nanotube catalysts in an acidic solution, in which the lignocellulose is hydrolyzed to small organic molecules (such as glucose, etc) by dilute H2SO4, and then the resulting glucose is oxidized by Mo2C catalyst to generate H2 are reported. During the photo-thermal catalytic processes, the carbon vacancy in Mo2C catalysts results in the generation of undercoordinated Mo sites, which act as active sites for both biomass oxidation and H2 generation reactions. Thus, the successful photo-thermal catalytic conversion of common agricultural and forestry biomass including polar wood chip, bamboo, wheat straw, rice straw, corncob, and rice hull into H2 fuel is realized, and the highest H2 generation rate achieves 30 µmolg-1h-1 in the wheat straw system. Outwork affords efficient noble-metal-free catalysts with adjustable active sites for photo-thermal catalytic conversion of lignocellulosic biomass into H2.

Robust Spray Combustion Enabling Hierarchical Porous Carbon-Supported FeCoNi Alloy Catalyst for Zn-Air Batteries.

Rechargeable Zn-air batteries (RZABs) are poised for industrial application, yet they require low-cost, high-performance catalysts that efficiently facilitate both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The pivotal challenge lies in designing multimetal active sites and optimizing the carbon skeleton structure to modulate catalyst activity. In this study, we introduce a novel hierarchical porous carbon-supported FeCoNi bifunctional catalyst, synthesized via a spray combustion method. The carbon, derived from sucrose, was tailored into a hierarchical porous morphology through etching with NO3- ions and NaCl, thereby significantly increasing the surface area for the interaction of the O2 and electrolyte interaction. The in situ formation of FeCoNi alloy nanoparticles ensures their uniform dispersion and anchoring, facilitating electron transport. The strong interaction and charge transfer at the heterogeneous FeCoNi alloy interfaces, along with nitrogen doping, which enhances the OER/ORR activity, endow the FeCoNi/N-PC catalyst with exceptional bifunctional catalytic properties, characterized by an activity parameter of 0.73 V. Furthermore, the RZAB assembled with this catalyst demonstrates outstanding cycling stability and reversibility, with a minimal round-trip efficiency decay of 7.6% over 1380 cycles (460 h) at 10 mA cm-2.

Effect of Silica–Alumina Ratio on Catalytic Cracking of Polyethylene over Mesoporous Silica–Zeolite Hierarchical Catalysts Produced by Gel Skeletal Reinforcement

Effect of Silica–Alumina Ratio on Catalytic Cracking of Polyethylene over Mesoporous Silica–Zeolite Hierarchical Catalysts Produced by Gel Skeletal Reinforcement

Selective hydrogenolysis of lignin over hierarchical CoNC catalysts for the sustainable production of 4-propylsyringol

A hierarchical CoNC catalyst was used for the selective production of 4-propylsyringol via a radical route during lignin hydrogenolysis.

The Synthesis, Characteristics, and Application of Hierarchical Porous Materials in Carbon Dioxide Reduction Reactions

The reduction of carbon dioxide to valuable chemical products could favor the establishment of a sustainable carbon cycle, which has attracted much attention in recent years. Developing efficient catalysts plays a vital role in the carbon dioxide reduction reaction (CO2RR) process, but with great challenges in achieving a uniform distribution of catalytic active sites and rapid mass transfer properties. Hierarchical porous materials with a porous hierarchy show great promise for application in CO2RRs owing to the high specific surface area and superior porous connection. Plenty of breakthroughs in recent CO2RR studies have been recently achieved regarding hierarchical porous materials, indicating that a summary of hierarchical porous materials for carbon dioxide reduction reactions is highly desired and significant. In this paper, we summarize the recent breakthroughs of hierarchical porous materials in CO2RRs, including classical synthesis methods, advanced characterization technologies, and novel CO2RR strategies. Moreover, by highlighting several significant works, the advantages of hierarchical porous materials for CO2RRs are analyzed and revealed. Additionally, a perspective on hierarchical porous materials for CO2RRs (e.g., challenges, potential catalysts, promising strategies, etc.) for future study is also presented. It can be anticipated that this comprehensive review will provide valuable insights for further developing efficient alternative hierarchical porous catalysts for CO2 reduction reactions.

Hierarchical Architectures by Hybridizing Ru Nanoparticles with Nitrogen/Oxygen Dual‐Doped Carbon Nanotubes for Advanced Hydrogen Evolution Reaction Performance

AbstractDeveloping highly efficient and stable electrocatalysts is critical for advancing hydrogen evolution reactions (HER) for hydrogen production. Herein, we report a facile approach to fabricating a hierarchical catalyst featuring ruthenium (Ru) nanoparticles uniformly integrated with nitrogen/oxygen co‐doped carbon nanotube aerogels (Ru‐NOCAs). Heteroatoms N and O‐modified CNTs can result in a negatively charged surface to effectively trap Ru3+ ions. Ru‐NOCAs exhibit a well‐defined hierarchical morphology facilitated by the self‐assembly of functional groups on the surface of CNTs, which enhances the interaction between Ru nanoparticles and CNTs. Due to the synergistic effect of hierarchical structure and strong interaction formation, Ru‐NOCAs show excellent catalytic activity and stability. Ru‐NOCAs catalyst demonstrates a remarkable overpotential of 41 mV at 10 mA cm−2 with a Tafel slope of 57 mV dec−1 in 1 M KOH and an overpotential of 68 mV with a Tafel slope of 65.8 mV dec−1 in 0.5 M H2SO4. These results indicate superior catalytic efficiency and enhanced charge transfer kinetics compared to the control samples. This study highlights the effectiveness of incorporating hierarchical structures and tailored surface chemistries in electrocatalyst design, offering new avenues for optimizing HER performance and advancing hydrogen fuel technology.

Rational desig of hierarchical defect-rich NiSe2/Se-NiCuOx heterostructures: Modulating electronic structure for exceptional ammonia oxidation performance

Rational desig of hierarchical defect-rich NiSe2/Se-NiCuOx heterostructures: Modulating electronic structure for exceptional ammonia oxidation performance

Accurate location of Ni and W active sites in hierarchical zeolite catalyst for the conversion of cellulose to alcohols

Accurate location of Ni and W active sites in hierarchical zeolite catalyst for the conversion of cellulose to alcohols

Hierarchical micro-meso-macroporous xAIL@HP UIO-66-NH2 catalysts used for efficient biodiesel production from low-grade acidic oils

Hierarchical micro-meso-macroporous xAIL@HP UIO-66-NH2 catalysts used for efficient biodiesel production from low-grade acidic oils