Powder Catalysts Research Articles

Promoted catalytic property of Cu/SSZ-13 by introducing a minority of Mn for NO removal from diesel engine exhaust

The Cu-exchanged SSZ-13 with the small-pore chabazite framework is considered as a highly efficient catalyst for selective catalytic reduction of NO with NH3 (NH3-SCR). In order to further improve the catalytic property, a series of Mn ion-assisted Cu/SSZ-13 powder catalysts were prepared by co-exchange method and stepwise exchange method. It is found that the NH3-SCR activity, N2 selectivity, hydrothermal stability and sulfur resistance of Cu/SSZ-13 are promoted by introducing a minority of Mn (0.15%–0.23%(mass)) through co-exchange method. Characterization results revel that the Cu,Mn co-exchange enables the higher amounts of Cu2+ active sites, the abundant medium strong and strong acid, the optimized ratio of lewis acid to Brønsted acid, etc., which are required for a good NH3-SCR catalytic property over broad temperature range and under harsh working environment. Moreover, a monolithic catalyst was prepared by impregnating a cordierite ceramic support into the coating slurry containing the optimized CuMn/SSZ-13 powder. The diesel engine bench tests show that Cu,Mn co-exchange gives the monolith catalyst a better catalytic property than commercial catalysts. This work provides an important guidance for the rational design of secondary-ion-assisted zeolites applied in NH3-SCR.

Construction of freestanding BiOBr/CCFs composites: Enhanced carrier separation achieving efficient photocatalytic performance

The recycling efficiency of the photocatalyst is an important factor in practical application, which is one of the problems that most powder catalysts need to solve urgently. Herein, the freestanding photocatalyst that BiOBr nanosheets anchored on coal-based carbon fibers (CCFs) has been prepared. Integrating BiOBr to CCFs nanosheets can enlarge the specific surface area of materials, broaden the light absorption range, and increase the carrier transport rate. The optimum BiOBr/CCFs-2 sample exhibits excellent photocatalytic degrade Rhodamine B (RhB) efficiency of 92 % within 20 min under visible light, and the kinetic constant is 2.6 times higher than that of BiOBr. The photogenerated carriers generated by BiOBr nanosheets transfer to CCFs with excellent electrical conductivity and then synergistically improving the photocatalytic performance of BiOBr/CCFs-2. The BiOBr/CCFs-2 still remain excellent photocatalytic activity and cycling stability after five cycles, and the composite will be expected to be widely applied in other fields.

Alkyl Radical Initiated Cyclization/Cascade for Synthesizing Lactam‐Substituted Alkyl Sulfones

Comprehensive SummaryAn alkyl radical initiated cyclization/tandem reaction of alkyl bromides and alkyl electrophiles by using potassium metabisulphite (K2S2O5) as a connector is developed for the synthesis of various lactam‐substituted alkyl sulfones. Notably, this process does not require a metal catalyst or metal powder reductant, highlighting its environmentally friendly features. The reaction demonstrates outstanding substrate adaptability and a high tolerance towards diverse functional groups. Furthermore, the biologically active molecules and commercially available drugs with a late‐stage modification are also highly compatible with this transformation. Mechanistic studies revealed that the reaction proceeds through a single‐step process involving intramolecular radical cyclization, "SO2" insertion, and external alkyl incorporation.

Effect of Polyethylene Pyrolysis Oil Hydrotreatment on the Pt/Al2O3 Catalyst: Experimental Characterization.

The dramatic increase in plastics production, coupled with a low recycling and recovery rate, has been a major challenge for sustainable practices and combating climate change. Hydrotreatment processing to upgrade fuel oils is a well-known process in the petroleum industry. In this work, we aim to investigate the catalyst properties before and after the hydrotreatment of pyrolysis oil derived from plastics, namely, linear low-density polyethylene, as no such report is available in the literature. Granular and powder forms of the Pt/Al2O3 catalyst were used in this study with characterization methods executed as such: transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and IR-RIS. XRD data show that the crystallinity of the catalyst support was unaffected by the hydrotreatment without any residues left, as the characteristic diffraction peaks were indicated for the crystalline phase of the support as 37.4, 39.8, 46.3, and 67.3°. In addition, the TGA experiments revealed that the carbon deposition on the spent catalyst was higher, as indicated by the higher weight loss (15.359%) compared to the fresh catalyst sample (11.43%). XPS analysis showed that the carbon deposition is more intense on the granular spent catalyst, as the intensity of the peaks is some 15 times greater than the peaks from the fresh catalyst. Also, compared to the observed peaks of the powder catalyst, less coke is formed. The band at 1624.05 cm-1 from the IR-RIS spectra was attributed to a shifted C=O band from the coke formation. The extension of these investigations using different catalysts to improve their characteristics and performance and to inhibit coke deposition will contribute to the incorporation of such processes in industry as well as the cost of fuels.

Precious metal-based Catalytic Membrane Reactors for continuous flow catalytic hydrodechlorination

This work is focused on the development of Catalytic Membrane Reactors (CMRs) comprising precious metals as active phases for a comparative assessment in continuous-flow catalytic hydrodechlorination (HDC). HDC has proved its remarkable potential for application as polishing step in drinking water treatment plants, but studies operating in continuous mode are scarce. Preliminary experiments were conducted in batch operation using Pd/Al2O3, Rh/Al2O3 and Pt/Al2O3 powder catalysts to evaluate the influence of the active phase on the removal of prochloraz (PCZ) (100 μg L−1), a pesticide listed on the EU Watch List (2022/1307), by HDC. PCZ removal was successfully described by a pseudo-first order kinetic equation and reaction pathways were proposed. Among the catalysts tested, Pt-based suffered a significant deactivation, not warranting the elimination of this micropollutant. Pd/Al2O3 exhibited a faster removal of PCZ than Rh/Al2O3, while this catalyst resulted in further hydrogenation of the non-chlorinated reaction product. Accordingly, different CMRs were developed by decorating cylindrical inert porous alumina membranes with Pd, Rh, and a combination of Pd-Rh as active phases (∼1% wt.). All CMRs showed a remarkable stability along 100 h on stream, being Pd/CMR be the most effective, with a pseudo-first order rate constant value of 0.062 min−1. An assessment of the impact of operating conditions (aqueous flow rate, PCZ initial concentration, temperature and H2 flow rate) was conducted using the Pd/CMR, which notably remained stable for 450 h on stream. The versatility of the system was finally demonstrated in tap water, achieving a steady-state PCZ conversion close to 95 %.

Water Condensation in the Nanoscale Pores of Pt/C Catalyst Particles and Its Impact on Catalyst Utilization: A Simulation Based on a Reconstructed Structure from Nanoimaging.

In polymer electrolyte membrane fuel cells, carbon-supported platinum (Pt/C) catalyst particles require sufficient water condensation within the nanoscale pores to effectively utilize the interior Pt catalysts. Since experimental visualizations with nanoscale precision of this phenomenon are not yet possible, we utilized a Pt/C catalyst particle reconstructed from segmented nanoimaging of a catalyst powder, which served as the computational domain for lattice density functional theory (LDFT) simulation of water condensation. Paired with experimental water uptake data, LDFT successfully simulated high-resolution water condensation, capturing both thin-film and capillary water condensation phenomena. Using a simple proton movement method within the water network, we reproduced the Pt utilization data from a CO stripping experiment. Our findings highlight that at low relative humidity (RH), Pt utilization is influenced by thin water film formations, mainly dictated by the wettability properties of surfaces within primary pores and the Pt/C catalyst particle's exterior. Conversely, at high RH, Pt utilization is attributed to capillary water condensation in medium-to-large sized pores. This approach contributes a qualitative and quantitative discussion on hypotheses regarding the mechanism of Pt utilization, supporting recent studies (e.g., Girod, R.; Nat. Catal. 2023, 6, (5), 383-391).

Investigation of long-term anti-sulfur and deactivation mechanism of monolithic Mn-Fe-Ce/Al2O3 catalysts for NH3-SCR: Changes in physicochemical and adsorption properties

Owing to the different reaction properties and deactivation mechanisms caused by the structural discrepancy of monolithic catalysts, abundant scientific results of powder or granular NH3-SCR catalysts have still not sufficiently robustly applied in recent years. Furthermore, minimal research has been focused on monolithic catalysts. As a result, this work prepared monolithic Mn-Fe-Ce/Al2O3 catalysts by active component impregnation (ACI-Mn-Fe-Ce/Al2O3) and precursor impregnation methods (PI-Mn-Fe-Ce/Al2O3) and investigates the long-term SO2 and H2O resistance of the catalysts. Compared with the PI-Mn-Fe-Ce/Al2O3 catalyst, the monolithic ACI-Mn-Fe-Ce/Al2O3 catalyst showed better performance. The catalytic activity follows a bell-shaped curve with an optimal performance at a drug loading of 5 %. The ACI-Mn-Fe-Ce/Al2O3 catalyst exhibits long-term resistance to SO2 and H2O and can still convert more than 70 % NOx after 168 h of SO2 and H2O resistance test. Characterization of the ACI-Mn-Fe-Ce/Al2O3 catalysts before and after the reaction showed that the reducibility decreased after the reaction, and more Mn4+ was transformed into Mn2+ to weaken the catalytic activity. However, more Fe2+ and Ce3+ were generated during the reaction, increasing the number of oxygen vacancies, oxygen defects, and hydroxyl-like groups, all of which would contribute to a certain extent to counteract the passivation effect of SO2 on the catalysts. In situ DRIFTs analysis shows that the formation of surface sulfates has a minimal effect on the adsorption of NO, but it does affect the adsorption of coordinated NH3 on Lewis acid sites. This work elucidates the deactivation details of Mn-Fe-Ce/Al2O3 catalysts from the perspective of physicochemical properties, which provides a reference for the development of better low-temperature SO2-resistance catalysts for industrial applications.

Ru-Ce0.7Zr0.3O2-δ as an Anode Catalyst for the Internal Reforming of Dimethyl Ether in Solid Oxide Fuel Cells.

The development of direct dimethyl ether (DME) solid oxide fuel cells (SOFCs) has several drawbacks, due to the low catalytic activity and carbon deposition of conventional Ni-zirconia-based anodes. In the present study, the insertion of 2.0 wt.% Ru-Ce0.7Zr0.3O2-δ (ruthenium-zirconium-doped ceria, Ru-CZO) as an anode catalyst layer (ACL) is proposed to be a promising solution. For this purpose, the CZO powder was prepared by the sol-gel synthesis method, and subsequently, nanoparticles of Ru (1.0-2.0 wt.%) were synthesized by the impregnation method and calcination. The catalyst powder was characterized by BET-specific surface area, X-ray diffraction (XRD), field emission scanning electron microscopy with an energy-dispersive spectroscopy detector (FESEM-EDS), and transmission electron microscopy (TEM) techniques. Afterward, the catalytic activity of Ru-CZO catalyst was studied using DME partial oxidation. Finally, button anode-supported SOFCs with Ru-CZO ACL were prepared, depositing Ru-CZO onto the anode support and using an annealing process. The effect of ACL on the electrochemical performance of cells was investigated under a DME and air mixture at 750 °C. The results showed a high dispersion of Ru in the CZO solid solution, which provided a complete DME conversion and high yields of H2 and CO at 750 °C. As a result, 2.0 wt.% Ru-CZO ACL enhanced the cell performance by more than 20% at 750 °C. The post-test analysis of cells with ACL proved a remarkable resistance of Ru-CZO ACL to carbon deposition compared to the reference cell, evidencing the potential application of Ru-CZO as a catalyst as well as an ACL for direct DME SOFCs.

Construction of multi-porous Ni-based monolithic catalyst by combining wood carbon and SBA-15 for strengthening CO2 methanation

Monolithic catalysts meet the needs of practical application compared with powder catalysts. In this work, we constructed a Ni-based monolithic catalyst (Ni/SAB-15/WWC) by in situ growth of rod-like mesoporous SBA-15 in the microchannels of wood carbon. The small Ni-based nanoparticles (∼5.3 nm) were uniformly dispersed into the mesoporous channels via a post-loading method. The monolithic Ni/SAB-15/WWC catalyst with a multilevel porous structure could provide a laminar gas flow on the surface of Ni active sites, increasing the low-temperature activity and high-temperature durability of CO2 methanation. The Ni/SAB-15/WWC with low Ni loading (∼2%) displayed superior CO2 methanation catalytic performance in terms of low-temperature activity and CH4 selectivity compared with the powder Ni/SAB-15 with high Ni loading (∼15 %). The combination of wood carbon and mesoporous materials is an innovative strategy for the design monolithic catalysts with low metal loading and excellent catalytic performance.

Comparative study of reactive oxygen species and tetracycline degradation pathways in catalytic peroxodisulfate activation by asymmetric mesoporous TiO2 and the corresponding controlled-release materials

The removal of trace amounts of antibiotics from water environments while simultaneously avoiding potential environmental hazards during the treatment is still a challenge. In this work, green, harmless, and novel asymmetric mesoporous TiO2 (A-mTiO2) was combined with peroxodisulfate (PDS) as active components in a controlled-release material (CRM) system for the degradation of tetracycline (TC) in the dark. The formation of reactive oxygen species (ROS) and the degradation pathways of TC during catalytic PDS activation by A-mTiO2 powder catalysts and the CRMs were thoroughly studied. Due to its asymmetric mesoporous structure, there were abundant Ti3+/Ti4+ couples and oxygen vacancies in A-mTiO2, resulting in excellent activity in the activation of PDS for TC degradation, with a mineralization rate of 78.6%. In CRMs, ROS could first form during PDS activation by A-mTiO2 and subsequently dissolve from the CRMs to degrade TC in groundwater. Due to the excellent performance and good stability of A-mTiO2, the resulting constructed CRMs could effectively degrade TC in simulated groundwater over a long period (more than 20 days). From electron paramagnetic resonance analysis and TC degradation experiments, it was interesting to find that the ROS formed during PDS activation by A-mTiO2 powder catalysts and CRMs were different, but the degradation pathways for TC were indeed similar in the two systems. In PDS activation by A-mTiO2, besides the free hydroxyl radical (·OH), singlet oxygen (1O2) worked as a major ROS participating in TC degradation. For CRMs, the immobilization of A-mTiO2 inside CRMs made it difficult to capture superoxide radicals (·O2−), and continuously generate 1O2. In addition, the formation of sulfate radicals (·SO4−), and ·OH during the release process of CRMs was consistent with PDS activation by the A-mTiO2 powder catalyst. The eco-friendly CRMs had a promising potential for practical application in the remediation of organic pollutants from groundwater.

ZSM-5@ceramic foam composite catalyst derived from spent bleaching clay for continuous pyrolysis of waste oil to produce monocyclic aromatic hydrocarbons

Spent bleaching clay, a solid waste generated during the refining process of vegetable oils, lacks an efficient treatment solution. In this study, spent bleaching clay was innovatively employed to fabricate ceramic foams. The thermal stability analysis, microstructure, and crystal phase composition of the ceramic foams were characterized by TG-DSC, SEM, and XRD. An investigation into the influence of Al2O3 content on the ceramic foams was conducted. Results showed that, as the Al2O3 content increased from 15 wt% to 30 wt%, there was a noticeable decrease in bulk density and linear shrinkage, accompanied by an increase in compressive strength. Additionally, the ceramic foams were used as catalyst supports, to synthesize ZSM-5@ceramic foam composite catalysts for pyrolysis of waste oil. The open pores of the ZSCF catalyst not only reduced diffusion path length but also facilitated the exposure of more acid sites, thereby increasing the utilization efficiency of ZSM-5 zeolite. This, in turn, engendered a significant enhancement in monocyclic aromatic hydrocarbons content from 39.15 % (ZSM-5 powder catalyst) to 78.96 %. Besides, a larger support pore size and a thicker ZSM-5 zeolite coating layer led to an increase in monocyclic aromatic hydrocarbons content. As the time on stream was extended to 56 min, the monocyclic aromatic hydrocarbon content obtained with the composite catalyst remained 12.41 % higher than that of the ZSM-5 powder catalyst. These findings validate the potential of the composite catalyst. In essence, this study advances the utilization of spent bleaching clay and introduces a novel concept for ceramic foam fabrication. Furthermore, it contributes to the scaling up of catalytic pyrolysis technology.

High-performance of ZnO/TiO2 heterostructured thin-film photocatalyst fabricated via atomic layer deposition

Oxide semiconductor is one of the most promising candidates for photocatalysts due to its light absorption ability, electronic properties, and stability. It is used in various applications such as solar-energy conversion, CO2 reduction, and water splitting. In this research, ZnO, TiO2, and ZnO/TiO2 heterostructured thin films are fabricated via atomic layer deposition (ALD), and their photocatalytic performances are evaluated. The film thickness can be controlled using ALD, and surface reactions can easily occur in thin films owing to the short distances between the active sites and charge carriers. In addition, unlike a powder catalyst, the bilayer photocatalyst is fixed in the solution; therefore, it does not make the solution turbid or disturb the light penetration. Diethylzinc and titanium tetraisopropoxide are used as precursors for Zn and Ti, and the thin films are deposited on soda-lime glass substrates at 150 °C using H2O as the reactant gas. The photocatalytic activity and stability are evaluated through photodegradation tests using methylene blue aqueous solution. The ZnO single-substance thin film exhibits a high degradation rate, but its performance significantly decreases after three consecutive experiments. The TiO2 single-substance thin film exhibits a relatively low degradation rate, but high reusability, exhibiting characteristics opposite to that of ZnO. Therefore, a TiO2 thin film is coated on ZnO to leverage both these advantages. The thin films are heat-treated at 400 °C for 10 min after deposition in a vacuum atmosphere. The surface morphology, crystal structure, and electrical characteristics of the photocatalyst specimens are analyzed through high-resolution scanning electron microscopy, Cs-corrected scanning transmission electron microscopy, and x-ray diffraction analysis. Their photocatalytic performances under ultraviolet (UV) irradiation are measured through UV–visible spectroscopy. The heat-treated ZnO/TiO2 heterostructured thin film exhibits a photodegradation rate exceeding 80%, with little degeneration after three cycles, indicating enhanced photodegradation performance and stability.

Mn-regulated CuFe2O4 spinel based active component continuous exsolution catalyst for long-term degradation of tetracycline

The development of catalysts with fast reaction rates and long service life remains a significant challenge in advanced oxidation processes. The research applied the property that Mn could occupy both tetrahedral and octahedral sites in the spinel structure. By adjusting Mn composition engineering in CuFe2O4, it could regulate the proportion of active components in spinel constituents and form the hybrid catalyst of Mn-doped CuFe2O4/CuO. CuFe2O4/CuO biphasic interface caused lattice distortion, effectively enhancing the interface interaction, which was conducive to the gradual exsolution and redeposition of the active component CuFe2O4 during the catalytic reaction process, thereby prolonging the service life of the catalyst. Within 30 min, the removal rate of tetracycline hydrochloride was 97.3%, while peroxymonosulfate (PMS) stoichiometric efficiency was 0.12. The degradation effect of the powder catalyst only decreased by 7.3% after 6 cycles. In the self-made fixed bed, the mass ratio of sodium alginate solidified catalyst to sewage treatment capacity could reach 1:33000. These results indicated that Mn doping could effectively improve the catalytic degradation performance of CuFe2O4 and prolong the service life of the catalyst by forming a two-phase interface. Furthermore, sodium alginate curing catalysts could provide new insights into the industrial application of catalysts.

Effect of physicochemical properties of carbons on the performance of bead-type Pd/C catalysts for furfural hydrogenation

In green heterogeneous catalytic systems, alginate has emerged as a promising material for transforming powder catalysts into solid forms because of its sustainability and non-toxicity. Herein, the effect of carbon supports, including activated carbon (AC), carbon black (CB), carbon nanotubes (CNT), and carbon nanofibers (CNF), on a bead-type Pd/alginate-carbon catalyst was studied. Bead-type supports were synthesized by alginate gelation, and Pd-supported bead-type catalysts were prepared by a chemical reduction method. The catalytic activity in the hydrogenation of furfural was evaluated. Physical properties such as the specific surface area and pore volume of the carbon support greatly influenced the properties of the bead-type Pd/C catalyst. Pd/CB-alginate bead (AB), which had the highest specific surface area and pore volume, exhibited the smallest Pd particle size and dispersion, resulting in the highest catalytic performance. Additionally, the catalyst exhibited the highest FF conversion of 99 % and tetrahydrofurfuryl alcohol selectivity of 92 % under 20 bar of H2 at 35 ℃ for 4 h.

Enhancing photocatalytic efficiency and durability: Ag-modified CNS–TiO2 thin films for sustainable industrial wastewater treatment

This study explores a novel approach to address the persistent challenges encountered in recovering powder catalysts and achieving superior photocatalytic performance tailored for environmental remediation and industrial wastewater (IE) treatment. Isopropyl alcohol (IPA), chosen as the solvent through Liyanage classical equations and zeta potential measurements (−33.6 mV), sets the stage for investigating the critical role of the surfactant (PVP) and binder (SiO2) in optimizing colloidal stability, thin-film coating, and photocatalytic activity. Meticulous experimentation reveals a synergistic 10:1 g/L ratio of PVP and SiO2 solutions as the key to achieving a delicate balance in enhancing colloidal stability, facilitating thin-film coating, and optimizing photocatalytic kinetics (84 ± 3%, k = 0.0303 ± 0.002 min−1). Additionally, the study emphasizes the need for a holistic optimization approach, highlighting colloidal stability and film adhesion to unlock the full potential of these advanced photocatalytic materials in engineering applications.

Thermochemical energy storage analysis of solar driven carbon dioxide reforming of methane in SiC-foam cavity reactor

Solar energy is an abundant renewable energy source, and the use of solar energy for carbon dioxide reforming of methane (CRM) is a promising thermochemical energy storage scheme, but the reactor using the traditional powder catalyst has the disadvantages of complex encapsulation and low energy storage efficiency. In this paper, porous SiC-foam with high thermal conductivity is used to prepare Ni/CeO2–Al2O3/SiC catalyst, and then is loaded into a cavity reactor to achieve highly efficient and stable CRM under solar simulator. After a period of reaction, methane conversion rate remains high. As inlet flow rate decreases and incident energy flux rises, methane conversion rate is improved, and thermochemical energy storage efficiency first rises and then drops with maximum 31.4%. The numerical model of the cavity reactor under concentrated heat flux is established, and the simulation results are in good agreement with the experimental data. The structure of catalyst bed directly influences the heat storage performance, and the optimal bed thickness, radius and porosity are obtained. For thick bed, the reverse reaction appears in the end region of the bed, and then this region expands with bed thickness rising, so the reaction rate first increases and then decreases.

Engineering Atomic Ag1-N6 Sites with Enhanced Performance of Eradication Drug-Resistant Bacteria over Visible-Light-Driven Antibacterial Membrane.

Utilizing visible light for water disinfection is a more convenient, safe, and practical alternative to ultraviolet-light sterilization. Herein, we developed silver (Ag) single-atom anchored g-C3N4 (P-CN) nanosheets (Ag1/CN) and then utilized a spin-coating method to fabricate the Ag1/CN-based-membrane for effective antibacterial performance in natural water and domestic wastewater. The incorporated Ag single atom formed a Ag1-N6 motif, which increased the charge density around the N atoms, resulting in a built-in electric field ∼17.2 times stronger than that of pure P-CN and optimizing the dynamics of reactive oxygen species (ROS) production. Additionally, the Ag1-N6 motif inhibited the release of Ag ions, ensuring good biocompatibility. Based on the first-principles calculation, the adsorption energy of O2 on the Ag1/CN (-0.32 eV) was lower than that of P-CN (-0.07 eV), indicating that loaded Ag single atom can lower the energy barrier for O2 activation, generating extra *OH radicals that cooperated with *O2- to effectively neutralize bacteria. As a result, the Ag1/CN powder-catalyst with the concentration of 30 ppm demonstrated a 99.9% antibacterial efficiency against drug-resistant bacteria (Escherichia coli, Staphylococcus aureus, kanamycin-resistant Escherichia coli, and methicillin-resistant Staphylococcus aureus) under visible-light irradiation for 4 h. This efficacy was 24.8 times higher than that of the P-CN powder catalyst. Moreover, the Ag1/CN-based-membrane can maintain a 99.9% bactericidal efficiency for natural water and domestic wastewater treatment using a homemade flow device, demonstrating its potential for water disinfection. Notably, the visible-light-driven antibacterial efficiency of the Ag1/CN catalyst outperformed the majority of the reported g-C3N4-based catalysts/membranes.

Synergistic effect between CoSx and MoS2 at the micrometer scale: Considerable promotion of the hydrodesulfurization of DBT

The future implementation of ultralow sulfur fuel regulations requires researchers to have an excellent understanding of the mechanism of the synergistic effect between the Co(Ni) and (Mo)W sulfides in supported Co(Ni)Mo(W)S hydrodesulfurization (HDS) catalysts. This synergistic effect occurs when the distance between two metals is on the mm or nm scale. To investigate the promotion of HDS on the µm scale, a series of Co and Mo multilayer flake catalysts with a thickness of 1 mm were prepared by laminate molding. The distance between CoSx and MoS2 in these specially structured catalysts was adjustable on the µm scale by controlling the order and quality of the catalyst powder. The results for the HDS of dibenzothiophene (DBT) demonstrate that there is an obvious synergistic effect between CoSx and MoS2 on the µm scale. The results of pyridine IR spectroscopy indicate that this synergy is due to CoSx and MoS2 synergistically generating more coordinatively unsaturated sites (CUSs) and -SH active sites at the μm scale, thus increasing the HDS activity. Moreover, the catalyst activity increases as the distance between CoSx and MoS2 decreases, and the fact that the feed comes into contact with CoSx first greatly improves the activity.

Continuous Direct Mechanocatalytic Suzuki-Miyaura Coupling via Twin-Screw Extrusion.

This work establishes the first direct mechanocatalytic reaction protocol within an extruder, focusing on the Suzuki-Miyaura reaction. Through the coating of either the extruder screws or barrel with Pd, we executed the cross-coupling reaction without the reliance on molecular catalyst compounds or powders, and solvents continuously. We identified the influence and interplay of crucial reaction parameters such as temperature, mechanical energy input, residence time, rheology, and catalyst contact time and finally obtained 36 % and 75 % of the reaction product after one and four reactor passes respectively.

The Synthesis of carbon dots//zincoxide (CDs/ZnO-H400) by using hydrothermal methods for degradation of ofloxacin antibiotics and reactive red azo dye (RR141)

The development of photocatalytic powders to remove contaminants from air solutions is an important field of research in the field of environmental conservation. CD/ZnO-H400, a heterogeneous photocatalytic production, is utilized to degrade the reactive red dye and the antibiotic ofloxacin found in wastewater. This study explains the synthesis of carbon dots (CDs) derived from coconut air and zinc oxide (ZnO) using a hydrothermal method at a temperature of 180 °C with a duration of 4 h and subsequently calcinated at a 400 °C temperature for 4 h. This shows a significant improvement in photocatalytic performance due to improved delivery efficiency at the interface. The cost-efficient use of solar energy allows the comprehensive elimination of harmful pollutants through detoxification. The removal of the contaminant takes place through the first-order reaction, with RR141 showing the highest constant rate at 0.03 min−1, while ofloxacin has a constant speed at 0.01 min−1. The photocatalytic stability is measured after five cycles. The study also tested the impact of sunlight on degradation, showing a degrading rate of 98% for RR141 and 96% for ofloxacin. This study displays a new catalyst powder synthesized from carbon dots derived from the air, coconut and ZnO, showing remarkable photoactivity to completely remove harmful dyes and antibiotics from the surrounding environment.