Catalytic Process Research Articles

Preparation of high-value carbon nanotubes from real waste plastic towards the negative carbon technology

The preparation of carbon nanotubes (CNTs) from plastics is of great significance for realizing high value utilization of waste and reducing carbon emission. Here, several kinds of real waste plastics were introduced into catalytic pyrolysis, and the process was also optimized. The results showed that the presence of impurities (e.g., adhesive labels) reduced the initial activation energy of the pyrolysis reaction, and the pyrolysis process was extended and could be divided into two stages. During the catalytic process, impurities play a toxic role on the catalyst at higher temperatures and result in the agglomeration of catalyst particles and a decrease in catalytic activity. Less than 10 wt.% carbon fibers were collected from milk cup waste. However, after experimental optimization, the influence of the impurity component was greatly reduced. The toxic effect of organic impurity volatiles on a catalyst was avoided by employing a segmented catalytic pyrolysis process, which led to an increase in solid carbon content of more than 20 % for express package waste. Simultaneously, more uniform and smoother CNTs can be found in the obtained solid carbon. The process of preparing carbon nanotubes with higher yield and better quality is feasible and has important application prospects in the utilization of waste plastics.

Decoration of marigold flower-like CoMo LDH on reinforced cow manure-derived biochar as an effective peroxymonosulfate activator for degradation of Bisphenol A in water

Marigold flower-like CoMo layered double hydroxide (LDH) was decorated on biochar derived from cow manure (CoMo@BC) to act as an efficient activator for peroxymonosulfate (PMS), enabling the degradation of Bisphenol A (BPA) in water. The CoMo@BC/PMS system can eliminate up to 98% of BPA at a concentration of 0.044mM within 15min. High efficacy is sustained in the pH range of 5 to 9, underscoring the robustness and adaptability of the system. Furthermore, the catalyst exhibits excellent stability, retaining activity over five consecutive cycles. Versatility is highlighted by the capability to degrade over 88% of various organic pollutants, indicating broad-spectrum applicability in water treatment. A comprehensive mechanistic study has elucidated three distinct degradation pathways and identified six intermediates of BPA, providing valuable insights into the catalytic process. Overall, the research underscores the potential of CoMo@BC as a highly effective catalyst for advanced water treatment applications through PMS activation. Significant efficacy in eliminating organic pollutants suggests great promise for enhancing the sustainability and efficiency of water purification technologies.

Modified Active Disturbance Rejection Control Design Based on Gain Scheduling for Selective Catalytic Reduction Denitrification Processes

Modified Active Disturbance Rejection Control Design Based on Gain Scheduling for Selective Catalytic Reduction Denitrification Processes

Promotion effect of nitrogen doping on the low-temperature NH3-SCR of NO over activated carbon: Characterization and mechanism analysis

Heteroatom nitrogen doping in carbon catalysts is recognized an effective strategy for tailoring the properties of carbon catalysts for various flue gas de-NOx applications. However, accurately discerning the active structures after nitrogen doping and elucidating the promotion effect on low-temperature selective catalytic reduction activity remains a formidable challenge under different nitrogen doping preparation conditions. In this study, a series of nitrogen-doped activated carbon catalysts was synthesized through the L16(45) orthogonal array design method, and the degree of influence of various preparation conditions on de-NOx catalytic activities was also assessed. The optimal preparation conditions determined by range analysis were employed to synthesize NOAC-17, achieving the NO conversion of 95% and N2 selectivity of 99% at 300 °C, respectively. Subsequently, various characterization results proved that nitrogen doping induced the formation of abundant basic groups. The imine, amide, amine, and N-6 groups altered the acid-base of the activated carbon surface and increased the adsorption of acidic NOx. The N-5 and N-Q groups enhanced electronic interaction in the carbon matrix and accelerated electron mobility in the catalytic reaction process. Moreover, the N-6 group played multiple roles beyond the aforementioned effect due to its special structure. It also enhanced the accumulation of oxygen vacancies, which were closely associated with further oxidation of adsorbed NO. The lone electron pair in the N-6 group within the activated carbon framework can alter the polarity of the catalyst, thereby exerting a positive influence on the adsorption and activation of NH3. The nitrogen-doped catalyst identified through range analysis of the orthogonal experiment primarily facilitated the NH3-SCR reaction via the E-R mechanism with supplementary contribution from L-H mechanism at low temperatures. The nitrogen doping conditions obtained for the activated carbon catalyst provide valuable insights for the strategic enhancement of its catalytic performance in low-temperature NH3-SCR reactions.

Application of metal organic frameworks ZIF-8-based solid catalyst with hierarchical porous structure and Brønsted-Lewis dual acid sites ionic liquids for sustainable biodiesel production from acidic soybean oil

In order to alleviate the mass transfer limitation of triglyceride macromolecules on the solid catalyst surface during the catalytic oil transformation process, the utilization of hierarchical porous solid catalyst is a feasible method. For reaching this goal, the hierarchical porous support of H-ZIF-8 was initially prepared by incorporating the three-dimensional ordered macro and mesoporous into the ZIF-8 using polystyrene spheres (PS) as a hard template. Subsequently, the phosphotungstate anion PW12O403- (PW) decorated sulfonated 4,4'-dipyridinium ionic liquid with Keggin structure, namely [DPySO3H]1.5PW, was encapsulated in the H-ZIF-8 support, with the formation of the novel [DPySO3H]1.5PW@H-ZIF-8 catalyst. The so-synthesized solid catalysts featured with ordered hierarchical porous structure and dual Lewis and Brønsted acidic properties, with large BET surface area of 267.38 m2/g. This catalyst had high catalytic performances for the concurrent transformation of triglycerides and free fatty acids to biodiesel in a heterogeneous manner. Under the optimal reaction parameters (methanol/oil molar ratio: 30:1; catalyst dosage: 4 wt%; reaction time: 8 h; reaction temperature: 130 °C), the oil conversion level of 91.2% and entire conversion of free fatty acids could be attained by applying this [DPySO3H]1.5PW@H-ZIF-8 catalyst. The high catalytic activity of this catalyst was due primarily to the increased mass transfer efficiency and synergism of Lewis and Brønsted acid sites. Moreover, the good FFA and moisture-resistance capacity was also shown for this catalyst even in the case of moisture content of 5 % and FFA content of 40 % in the oil feedstock. This solid catalyst could be reused by simple filtration and displayed good reusability, still attaining over 80% oil conversion at the fourth reuse cycles thanks to the robust interactions between the acidic active centers and the hierarchical porous support. The kinetic analysis indicated that the activation energy Ea and Arrhenius constant A for this solid acid-catalyzed transesterification process were 56.0 kJ/mol and 7.8×104 min-1, respectively. This research would provide a new approach for the development of hierarchical porous solid catalysts, enabling the one-step transformation of low-grade acidic oils into biodiesel in a more sustainable and environmentally friendly way.

Constructing a 3D ordered macroporous cobalt monoatomic catalyst for efficient SMX degradation via PMS activation

The cobalt monoatomic catalyst with 3D ordered macropores structure (3DOM Co/NC) was prepared using the crystalline porous material ZIF-67 and SiO2 as the precursor and template, and used to investigate the effect of its activation with peroxymonosulfate (PMS) on sulfamethoxazole (SMX) removal. The mesoporous structure mostly retained after ZIF-67 carbonisation, and the formation of new homogeneous macropores after the removal of the SiO2 template, which greatly increases the surface area of the catalyst (429 m2 g-1) and promotes long-range mass transfer. Additionally, Co monoatomic sites were formed in the porous skeleton, providing electrons that were utilised for the activation of PMS. This distinctive structure enables it to almost completely degrade of 20 ppm SMX within 3min and show excellent catalytic degradation efficiency in a wide pH range (3.0-9.0) and high-salinity simulated wastewater (10-100mM). In addition, the main ROS in the catalytic degradation process were explored as 1O2 and O•2-. Combined with the results of DFT calculations and product analyses, the active sites of SMX were predicted and the degradation pathways and mechanisms were inferred, confirming that the degradation process of SMX poses a low risk of toxicity to the environment. This study reveals that the addition of 3DOM Co/NC was more favourable for the activation of PMS for SMX degradation, which contributes to the development and improvement of advanced oxidation processes for environmental remediation.

The catalytic reduction-oxidation collaborative processes for enhanced elimination of TBBPA over Pd/CeO2-R catalyst

The degradation of tetrabromobisphenol A (TBBPA) was inhibited due to the existence of strong electron attraction Br. The reduction of TBBPA usually generated bisphenol A (BPA), which still do harm to the environment. Herein, we prepared Pd/CeO2 catalysts for the valid elimination of TBBPA with clean products via the catalytic hydrodebromination-oxidation (R-O) synergy processes. TBBPA suffered debromination and BPA and Br- were the products after reaction for 60min during the catalytic hydrodebromination (HDBr) processes, BPA could be degraded smoothly in the following oxidation step involved PMS activation, reflecting an excellent ability of the Pd based catalyst for the activation of H2, C-Br bond and PMS. Both Pd0 and Pdn+ played key roles for the HDBr of TBBPA, while Pd0 was the main active sites for the oxidation of BPA. HOBr generated from Br- oxidation favored the removal of BPA while the reactive species such as 1O2 generated from PMS activation further accelerated the TOC removal. The TOC removal rate was 5.2% for the direct degradation of TBBPA in the PMS/DP-Pd/CeO2-R system, while this value increased to 57.5% in the R-O synergy system. In addition, after reaction for 120min to eliminate TBBPA, the products were friendly to the aquatic organisms in the R-O synergy system, while the products remain exhibited strong toxicity in the single oxidation system, highlighting the advantages of the Pd/CeO2 catalyst triggered reduction/oxidation cooperation processes.

Cu-S-Mo Interfacial Sites in CuO2@MoS2/PLLA Scaffolds for Robust Synergistic Antibacterial Efficacy via CDT and PTT

Bacterial infections considerably limit the success of scaffold transplantation. CuO2 may generate hydroxyl radicals through a self-cascade catalytic process, which is effective for sterilization. However, reducing CuO2-derived Cu+ ions to Cu° can lead to a decline in catalytic activity. To overcome these limitations, we anchored CuO2 onto MoS2 to establish stable Cu-S-Mo interfacial sites. The CuO2/MoS2 nanozyme was fabricated using a low-temperature co-precipitation technique and introduced into poly-L-lactic acid scaffolds using selective laser sintering. The Cu-S-Mo interfacial sites showed a triad of functions that synergistically enhanced catalytic performance. These sites stabilized the Cu atoms, augmented catalytic activity by facilitating efficient electron transfer through the Mo4+/Mo6+ redox couple, and improved the conduction of heat derived from the photothermal response of MoS2 to the Cu catalyst. The synergistic action of chemodynamic and photothermal therapy, mediated by the Cu-S-Mo sites, resulted in remarkable antibacterial efficacy, with 92.3% and 93.5% inhibition rates against Staphylococcus aureus and Escherichia coli, respectively. Experimental evidence and simulations demonstrated that Cu-S-Mo structure stabilized the Cu atoms and improved electron transfer via interatomic charge transfer. These results highlight the potential of the CuO2@MoS2/PLLA scaffold in eliminating bacterial infections.

Catalytic Degradation of Acid Orange 7 Using CoFe2O4@Biochar Heterogeneous Catalytic Ozonation Process in Aqueous Solutions

Catalytic Degradation of Acid Orange 7 Using CoFe2O4@Biochar Heterogeneous Catalytic Ozonation Process in Aqueous Solutions

Second Generation Zwitterionic Aza‐Diarylethene: Photoreversible CN Bond Formation, Three‐State Photoswitching, Thermal Energy Release, and Facile Photoinitiation of Polymerization

AbstractDiarylethenes are a well‐studied and optimized class of photoswitches with a wide range of applications, including data storage, smart materials, or photocontrolled catalysis and biological processes. Most recently, aza‐diarylethenes have been developed in which carbon‐carbon bond connections are replaced by carbon‐nitrogen connections. This structural elaboration opens up an entire new structure and property space expanding the versatility and applicability of diarylethenes. In this work, we present the second generation of zwitterionic aza‐diarylethenes, which finally allows for fully reversible photoswitching and precise control over all three switching states. High‐yielding photoswitching between the neutral open form and a zwitterionic Z isomer is achieved with two different wavelengths of light. The third zwitterionic E isomeric state can be reached in up to 87 % upon irradiation with a third wavelength. Its high energy content of >10 kcal/mol can be released thermally by deliberate solvent change as trigger mechanism, rendering aza‐diarylethenes into interesting candidates for molecular solar thermal energy storage (MOST) applications. The third state also serves as locking state, allowing to toggle light‐responsiveness reversibly between thermally labile and thermally stable switching. Further, irradiation of the zwitterionic states leads to highly efficient photopolymerization of methyl acrylate (MA), directly harnessing the unleashed chemical reactivity of our aza‐diarylethene in a materials application.

Second Generation Zwitterionic Aza-Diarylethene: Photoreversible CN Bond Formation, Three-State Photoswitching, Thermal Energy Release, and Facile Photoinitiation of Polymerization.

Diarylethenes are a well-studied and optimized class of photoswitches with a wide range of applications, including data storage, smart materials, or photocontrolled catalysis and biological processes. Most recently, aza-diarylethenes have been developed in which carbon-carbon bond connections are replaced by carbon-nitrogen connections. This structural elaboration opens an entire new structure and property space expanding versatility and applicability of diarylethenes. In this work, we present the second generation of zwitterionic aza-diarylethenes, which finally allows for fully reversible photoswitching and precise control over all three switching states. High-yielding photoswitching between the neutral open form and a zwitterionicZisomer is achieved with two different wavelengths of light. The third zwitterionicEisomeric state can be reached up to 87% upon irradiation with a third wavelength. Its high energy content of >10 kcal/mol can be released thermally by deliberate solvent change as trigger mechanism, rendering aza-diarylethenes into interesting candidates for molecular solar thermal energystorage (MOST) applications. The third state further serves as locking state, allowing to toggle light-responsiveness reversibly between thermally labile and thermally stable switching. Further, irradiation of the zwitterionic states leads to highly efficient photopolymerization of methyl acrylate (MA),directly harnessing the unleashed chemical reactivity of aza-diarylethene in materials applications.

Localized Oxidative Catalytic Reactions Triggered by Cavitation Bubbles Confinement on Copper Oxide Microstructured Particles.

Efficient energy transfer management in catalytic processes is crucial for overcoming activation energy barriers while minimizing costs and CO2 emissions. We exploit here a concept of CuO particle design with multiple gas-stabilizing sites, engineered to function as cavitation nuclei and catalysts. This concept facilitates the selective and efficient acoustic energy transfer directly to the catalyst surface, avoiding the undesired dissipation of acoustic energy into the bulk solution while demonstrating superior cavitation properties at lower acoustic pressure amplitudes. Utilizing a chemical thermometric approach, we demonstrate that the local temperature on the surface of our CuO particles during cavitation bubble implosions can create an effective equivalent temperature of about 360 °C. This temperature effect facilitates the efficient catalysis of oxidative reactions using an organic pollutant probe molecule. Density functional theory (DFT) calculations were used to assess the decomposition of H2O2 and of pollutant probe molecule on CuO (111). Our work represents a significant advance in sonocatalytic systems, promising efficient energy use in catalytic reactions.

Localized Oxidative Catalytic Reactions Triggered by Cavitation Bubbles Confinement on Copper Oxide Microstructured Particles.

AbstractEfficient energy transfer management in catalytic processes is crucial for overcoming activation energy barriers while minimizing costs and CO2 emissions. We exploit here a concept of CuO particle design with multiple gas‐stabilizing sites, engineered to function as cavitation nuclei and catalysts. This concept facilitates the selective and efficient acoustic energy transfer directly to the catalyst surface, avoiding the undesired dissipation of acoustic energy into the bulk solution while demonstrating superior cavitation properties at lower acoustic pressure amplitudes. Utilizing a chemical thermometric approach, we demonstrate that the local temperature on the surface of our CuO particles during cavitation bubble implosions can create an effective equivalent temperature of about 360 °C. This temperature effect facilitates the efficient catalysis of oxidative reactions using an organic pollutant probe molecule. Density functional theory (DFT) calculations were used to assess the decomposition of H2O2 and of pollutant probe molecule on CuO (111). Our work represents a significant advance in sonocatalytic systems, promising efficient energy use in catalytic reactions.

Spin Crossover and Its Application in Organometallic Catalysis: Concepts and Recent Progress.

Spin crossover is one of the most important properties of open-shell metal complexes. In organometallic catalytic reactions, catalysts can alter reaction kinetics by spin crossover, i. e., accelerating or hindering the reaction progression, as well as altering reaction pathways, modulating the reaction selectivity or promoting new reactions. This personal account outlines the introduction and development of important concepts such as "two-state reactivity" involving spin crossover, and proposes a new concept, "spin-responsive catalysis" to summarize the catalytic processes in which spin effects are present. Finally, the electronic mechanism of spin crossover accelerating the reaction and the role of spin crossover in changing the reaction path and regulating the reaction selectivity are introduced by taking two recent typical iron-catalyzed reactions recently reported by our group as examples.

Engineering Single Ni Sites on 3D Cage‐like Cucurbit[n]uril Ligands for Efficient and Selective CO2 Photocatalytic Reduction

AbstractSolar‐driven CO2 selective reduction with high conversion is a challenging task yet holds immense promise for both CO2 neutralization and green fuel production. Enhancing CO2 adsorption at the catalytic centre can trigger a highly efficient CO2 capture‐to‐conversion process. Herein, we introduce cucurbit[n]urils (CB[n]), a new family of molecular ligands, as a key component in the creation of a 3D cage‐like metal (nickel, Ni)‐complex molecular co‐catalyst (CB[7]‐Ni) for photocatalysis. It exhibits an unprecedented CO yield rate of 72.1 μmol ⋅ h−1 with a high selectivity of 97.9 % under visible light irradiation. To verify the origin of the carbon source in the products, a straightforward isotopic tracing method is designed based on tandem reactions. The catalytic process commences with photoelectron transfer from Ru(bpy)32+ to the Ni2+ site, resulting in the reduction of Ni2+ to Ni+. The locally enriched CO2 molecules in the cage ligand CB[7] undergo selective reduction by the Ni+ nearby to form CO product. This work exemplifies the inspiring potential of ligand structure engineering in advancing the development of efficient unanchored molecular co‐catalysts.

Robust Organocatalytic Three-Component Approach to 1,3-Diarylallylidene Pyrazolones via Consecutive Double Condensation Reactions.

A robust pyrrolidine-BzOH salt-catalyzed one-pot three-component reaction involving 4-unsubstituted pyrazolones, aryl/heteroarylaldehydes, and aryl methyl ketones is reported for the first time. This catalytic process fortifies an efficient method, allowing for the practical synthesis of a wide array of synthetically useful 1,3-diarylallylidene pyrazolones in good to high yields exclusively in their single geometrical isomer forms. Furthermore, this catalyst facilitates a sequential double condensation reaction under thermal conditions, thereby enabling two consecutive C═C bonds through displacement of aryl groups. Moreover, this organocatalytic technique achieves a 100% carbon atom economy, marking a significant step forward toward efficient and sustainable synthesis.

Engineering Single Ni Sites on 3D Cage-like Cucurbit[n]uril Ligands for Efficient and Selective CO2 Photocatalytic Reduction.

Solar-driven CO2 selective reduction with high conversion is a challenging task yet holds immense promise for both CO2 neutralization and green fuel production. Enhancing CO2 adsorption at the catalytic centre can trigger a highly efficient CO2 capture-to-conversion process. Herein, we introduce cucurbit[n]urils (CB[n]), a new family of molecular ligands, as a key component in the creation of a 3D cage-like metal (nickel, Ni)-complex molecular co-catalyst (CB[7]-Ni) for photocatalysis. It exhibits an unprecedented CO yield rate of 72.1 μmol ⋅ h-1 with a high selectivity of 97.9 % under visible light irradiation. To verify the origin of the carbon source in the products, a straightforward isotopic tracing method is designed based on tandem reactions. The catalytic process commences with photoelectron transfer from Ru(bpy)3 2+ to the Ni2+ site, resulting in the reduction of Ni2+ to Ni+. The locally enriched CO2 molecules in the cage ligand CB[7] undergo selective reduction by the Ni+ nearby to form CO product. This work exemplifies the inspiring potential of ligand structure engineering in advancing the development of efficient unanchored molecular co-catalysts.

Nanomaterials for Energy Conversion

Nanomaterials have emerged as a cornerstone in advancing energy conversion technologies, offering unparalleled potential for improving efficiency and sustainability. Their unique properties—such as high surface area, tunable electronic structure, and quantum effects—enable superior performance in applications like solar cells, fuel cells, thermoelectric devices, and batteries. By manipulating nanoscale architectures, researchers can enhance energy harvesting, storage, and conversion processes. This study explores the role of nanomaterials in energy conversion, focusing on their design, synthesis, and application in cutting-edge technologies. The integration of nanomaterials with advanced energy systems has shown significant potential to address challenges such as limited energy resources and environmental concerns. Special emphasis is placed on nanostructured semiconductors, quantum dots, and graphene-based materials for their contributions to photovoltaic and catalytic processes. Despite their advantages, challenges remain, including scalability, stability, and cost-efficiency. This research aims to provide a comprehensive overview of recent advancements, evaluate existing challenges, and highlight future directions for nanomaterials in energy conversion, ultimately contributing to a sustainable energy future.

In Situ Raman Study of Layered Double Hydroxide Catalysts for Water Oxidation to Hydrogen Evolution: Recent Progress and Future Perspectives

With the increasing global emphasis on green energy and sustainable development goals, the electrocatalytic oxygen evolution reaction (OER) is gradually becoming a crucial focus in research on water oxidation for hydrogen generation. However, its complicated reaction processes associated with its high energy barrier severely limit the efficiency of energy conversion. Recently, layered double hydroxide (LDH) has been considered as one of the most promising catalysts in alkaline media. Nonetheless, lacking a deep insight into the kinetic process of the electrocatalytic OER process is detrimental to the further optimization of LDH catalysts. Therefore, monitoring the catalytic reaction kinetic process via surface-sensitive in situ spectroscopy is especially important. In particular, the in situ Raman technique is capable of providing fingerprint information for surface species and intermediates in the operating environment. From the perspective of Raman spectroscopy, this paper provides an exhaustive overview of research progress in in situ Raman for the characterization of the catalytic mechanism of LDH catalysts, providing theoretical guidance for designing LDH materials. Finally, we present an incisive discussion on the challenges of the electrocatalytic in situ Raman technique and its future development trend.

Polarized Bimetallic Site Synergy in Ionic Structures of Cu(II), Fe(III), and Mn(III) Porphyrins: Electrochemistry and Catalytic Hydrogenation of Nitroaromatics.

Binuclear catalytic sites attained in a controlled way with complementary and cooperative metal ion centers are highly relevant in the development of new or enhanced catalytic processes. Herein, binuclear sites carrying Fe(III), Cu(II), or Mn(III) metal ions with a polarized structure have been prepared using the ionic self-assembly of oppositely charged metalloporphyrins. Binary porphyrin structures (BIPOS) have been prepared based on metalloporphyrin cations carrying pyridinium or methylpyridinium groups in conjugation with metalloporphyrin anions carrying sulfonatophenyl groups. BIPOS carrying [cation/anion] tecton pairs of [Cu/Fe], [Fe/Cu], [Cu/Cu], [Fe/Fe], [Mn/Fe], [Fe/Mn], and [Mn/Mn] have been compared. Electrochemical interaction and enhanced catalytic behavior are noticeable for BIPOS [Fe/Cu], [Fe/Fe], and [Mn/Fe] carrying a Fe center and [less electronegative/more electronegative] metal ion centers in the [cation/anion] porphyrin ionic pairs. For high-performance BIPOS, cyclic voltammograms showed a greater separation of the cathodic and anodic peaks, within ΔEp = 0.095-0.125 V, and the rate constants for the catalytic reduction of 4-nitrophenol were within k = 0.380-0.535 min-1/mg of catalyst, significantly superior to the related individual metalloporphyrins. Inverse heterobimetallic [Cu/Fe] and [Fe/Mn] and the homometallic BIPOS [Cu/Cu] and [Mn/Mn] were significantly less active or inefficient. A [Fe/Cu] material could be reused in at least 5 catalytic cycles, maintaining catalytic activity; the best catalysts were also active in the reduction of nitrobenzene to aniline in mild conditions (visible light, 30 °C, 0.5 mol % catalyst), and an [Fe/Fe] catalyst showed 100% aniline yield after 2 h.