High Catalytic Efficiency Research Articles

Analysis of the Behavior of Deep Eutectic Solvents upon Addition of Water: Its Effects over a Catalytic Reaction.

This study presents the potential role of deep eutectic solvents (DESs) in a lipase-catalyzed hydrolysis reaction as a co-solvent in an aqueous solution given by a phosphate buffer. Ammonium salts, such as choline chloride, were paired with hydrogen bond donors, such as urea, 1,2,3-propanetriol, and 1,2 propanediol. The hydrolysis of p-nitrophenyl laureate was carried out with the lipase Candida antarctica Lipase B (CALB) as a reaction model to evaluate the solvent effect and tested in different DES/buffer phosphate mixtures at different % w/w. The results showed that two mixtures of different DES at 25 % w/w were the most promising solvents, as this percentage enhanced the activities of CALB, as evidenced by its higher catalytic efficiency (kcatKM). The solvent analysis shows that the enzymatic reaction requires a reaction media rich in water molecules to enable hydrogen-bond formation from the reaction media toward the enzymatic reaction, suggesting a better interaction between the substrate and the enzyme-active site. This interaction could be attributed to high degrees of freedom influencing the enzyme conformation given by the reaction media, suggesting that CALB acquires a more restrictive structure in the presence of DES or the stabilized network given by the hydrogen bond from water molecules in the mixture improves the enzymatic activity, conferring conformational stability by solvent effects. This study offers a promising approach for applications and further perspectives on genuinely green industrial solvents.

Solid-State Oxidation of Alcohols in Gold-Coated Milling Vessels via Direct Mechanocatalysis.

This paper presents a novel approach for the selective oxidation of alcohols to their corresponding aldehydes through direct mechanocatalysis, employing a gold-coated milling vessel as catalyst and air as the oxidation agent. By adjusting milling frequency, media, and duration, high catalytic efficiencies and selectivities are achieved. Remarkably, yields of up to 99 % are obtained for specific substrates, with a turnover number (TON) of 8200 and a turnover frequency (TOF) of 0.77 s-1, surpassing existing alternatives. Confirmation of the catalytic reaction indeed occurring on the milling tool surface was achieved through X-ray photoelectron spectroscopy (XPS).

Festphasen‐Alkoholoxidation mittels Direkter Mechanokatalyse

AbstractDiese Publikation stellt einen neuartigen Ansatz für die selektive Oxidation von Alkoholen zu den entsprechenden Aldehyden durch direkte Mechanokatalyse vor, wobei ein mit Gold beschichtetes Mahlgefäß als Katalysator und Luftsauerstoff als Oxidationsmittel verwendet werden. Durch die Anpassung der Mahlfrequenz, der Mahlmedien und der Mahlzeit werden hohe Katalysatoraktivität und Selektivitäten erreicht. Zudem werden für bestimmte Substrate Ausbeuten von bis zu 99 % erzielt, sowie eine Turnover Number (TON) von 8200 und eine Turnover Frequency (TOF) von 0,77 s−1, was bestehende Alternativen übertrifft. Mittels Röntgenphotoelektronenspektroskopie (XPS) konnte bestätigt werden, dass die katalytische Reaktion tatsächlich auf der Oberfläche des Mahlwerkzeugs stattfindet.

Biomass carbon quantum dots: Mimicking peroxidase-like activity and sensitive fluorometric and colorimetric detection of dopamine hydrochloride in meat products

Dopamine (DH), as a kind of "lean meat powder", is easily accumulated in animal tissues and further endangers the health of consumers. As a result, developing a quick, sensitive, and cost-effective approach for detecting DH concentration is critical to food safety. In this paper, fluorescent carbon quantum dot (CQDs) peroxidase mimetic enzymes with remarkable stability and high catalytic efficiency were produced utilizing a green synthesis technique from three types of food waste: corncob, sunflower seed husk, and grape seed. Then a colorimetric/fluorescent dual-mode sensor based on fluorescent CQDs was developed for the visual detection of dopamine hydrochloride in pork through changing the fluorescence brightness and color caused by its catalysis. The fluorescent CQDs generated from the three wastes were characterized, and the ones based on corncob performed the best as mimicked enzymes. Therefore, corncob fluorescent CQDs (CFCD) were used for the detection of DH. Under the optimal conditions, the linear range of DH measured by the fluorescent technique was 0.001–0.6 mmol/L (R2 = 0.9947), with a detection limit of 7.86 nmol/L. The linear range of DH measured by the colorimetric technique was 0.001–0.7 mmol/L (R2 = 0.9952), with a detection limit of 0.93 μmol/L. And with its high sensitivity and selectivity, it was successfully applied to the detection of DH in real samples. The developed CFCD concept may provide a novel method for the detection of DH. This comprehensive strategy promotes the high-efficiency conversion of biomass into CQDs and provides a theoretical basis for exploring the treatment of biomass waste.

Magnetic PdNi@CN as a versatile catalyst for Suzuki reaction and 4-nitrophenol reduction

Palladium-based non-homogeneous catalysts have attracted considerable attention due to their high catalytic efficiency and adaptability. However, they still face the challenges of long reaction routes and poor cycling stability. An economical, efficient, stable and environmentally friendly catalyst PdNi@CN was prepared by loading nickel-palladium nanoparticles onto nitrogen-doped carbon functionalized carrier material. The catalyst was thoroughly characterized using XRD, XPS, SEM, TEM, VSM, and ICP. PdNi@CN could efficiently catalyze the Suzuki coupling reaction (Iodobenzene and phenylboronic acid, 97 % yield, TON (Turnover Number)=1.62 × 102, TOF (Turnover Frequency)=2.43 × 102 h-1). Furthermore, PdNi@CN exhibited high activity in the reduction of 4-nitrophenol (4-NP, Kapp=8.01 × 10–2 s-1). After five cycles of catalysis, the conversion of 4-NP still reached 95 %, demonstrating the excellent structural stability and high catalytic performance of PdNi@CN.

Facile fabrication of chitosan/bone/bamboo biochar beads for simultaneous removal of co-existing Cr(VI) and bisphenol a from water

Heavy metal Cr(VI) and organic BPA have posed harmful risks to human health, aquatic organisms and the ecosystem. In this work, Chitosan/bone/bamboo biochar beads (CS-AMCM) were synthesized by co-pyrolysis and in situ precipitation method. These microbeads featured a particle size of approximately 1 ± 0.2 mm and were rich in oxygen/nitrogen functional groups. CS-AMCM was characterized using XRD, Zeta potential, FTIR, etc. Experiments showed that adsorption processes of CS-AMCM on Cr(VI) and BPA fitted well to Langmuir model, with theoretical maximum capacities of 343.61 mg/g and 140.30 mg/g, respectively. Pore filling, electrostatic attraction, redox, complexation and ion exchange were the main mechanisms for Cr(VI), whereas for BPA, the intermolecular force (hydrogen bond) and pore filling were involved. CS-AMCM with adsorbed Cr(VI) demonstrated effective activation in producing ·OH and ·O2 from H2O2, which degraded BPA and Cr(VI) with the removal rates of 99.2% and 98.2%, respectively. CS-AMCM offers the advantages of low-cost, large adsorption capacity, high catalytic degradation efficiency, and favorable recycling in treating Cr(VI) and BPA mixed wastewater, which shows great potential in treating heavy metal and organic matter mixed pollution wastewater.

Antimicrobial framework nucleic acid‐based DNAzyme cluster with high catalytic efficiency

AbstractBACKGROUNDHydroxyl radical‐mediated materials primarily liberate more reactive and acutely lethal hydroxyl radical (•OH) and act as potent bactericidal antibiotics, for example H2O2. Hydroxyl radical possess higher tendency than that of H2O2 to attack various biological molecules such as DNA, proteins and iron–sulfur clusters, and impair their proper functioning, actively leading to strongly potent bactericidal effect. To acquire the desired antimicrobial effect, high concentration of H2O2 is required that has found medically harmful to healthy tissues of humans.RESULTSWe herein report framework nucleic acid‐regulated DNAzyme cluster (FDC) – that is, peroxidase‐like hemin‐bound G‐quadruplex (G4/H) DNAzyme – to amplify the catalytic reduction potential of G4/H complex, leading to high conversion rate of H2O2 to more reactive hydroxyl radical that potentially shows the same antibacterial efficiency at lower and safer H2O2 concentration. Specifically, we have grafted multiple copies of DNAzymes outside framework nucleic acid (FNA) to successively achieve 3–9 orders of magnitude enhancement in catalytic activity and antibacterial efficiency of FDC.CONCLUSIONOur designed FDC has successfully alleviated H2O2 toxicity and increased its efficiency as antibacterial material, as FDC amplified the catalytic reduction potential of G4/H DNAzyme, leading to high conversion rate of H2O2 to more reactive •OH that potentially shows the same antibacterial efficiency at lower and safer H2O2 concentration. © 2024 Society of Chemical Industry (SCI).

Electrochemical degradation of small molecule dyes by TiO2-decorated polyacrylonitrile nanofiber membranes with superior properties

To optimize the uniform dispersion of nanoparticles and enhance their catalytic degradation effect on small molecule dyes in textile wastewater, titanium dioxide (TiO2) was deposited on polyacrylonitrile (PAN) fiber membranes using magnetron sputtering technology, and TiO2/PAN nanofiber membrane (NFM) with low content and high catalytic efficiency was successfully prepared. Through membrane separation coupling electrocatalysis, the composite membranes exhibited outstanding performance in removing Congo red (CR), Sunset yellow (SY), Methyl orange (MO), and Methylene blue (MB) dyes, with removal rates of 99.5%, 98.8%, 98.5%, and 87.2% respectively. Even after continuous catalysis for 10 h, the composite membranes maintained a high dye removal rate, demonstrating their remarkable stability and water treatment capabilities. Furthermore, TiO2/PAN NFMs displayed high pure water permeance, dye permeance, and mechanical strength. Specifically, M20 (magnetron sputtering time of 20 min) showed water permeance and dye (SY) permeance values of 1944 L·m−2·h−1·bar−1 and 816 L·m−2·h−1·bar−1, respectively, and indicate superior mechanical and electrochemical properties. During the electrocatalytic process, TiO2/PAN NFMs generated reactive oxygen species (ROS) on the surface, imparting a self-cleaning property that extended the service life of the membranes and offered an effective solution for textile wastewater treatment.

Synergistic removal of tetracycline in water with highly stable Lac immobilized on magnetic metal-organic framework

The arbitrary discharge of tetracycline (TC) residuals has seriously influenced the ecosystem and human health. Laccase (Lac)-based biodegradation technology is considered a more effective way to remove TC due to its high catalytic efficiency and less by-product. Nevertheless, free Lac suffers from poor stability, easy inactivation and difficult recovery, restricting its application. Immobilization of Lac is considered an efficient strategy for addressing these obstacles. In this study, a magnetic metal-organic framework of Fe3O4@SiO2@UiO-66-NH2 (MMOF) was prepared and used as a carrier to immobilize Lac (Lac@MMOF) for TC degradation. Benefiting from the multiple binding sites, adsorption, and protection effect of MMOF, Lac@MMOF displayed a wider pH application range (2–7) and better thermal (15–85 °C), repeatability, and storage stability than free Lac. Furthermore, owing to the synergism of MOF adsorption and Lac biocatalysis, the removal rate of Lac@MMOF for TC could be up to 98 % at pH = 7 within 1 hr, which was 1.29 and 1.24 times that of free Lac and MMOF, respectively. More importantly, Lac@MMOF could easily be separated from aqueous solution under a magnetic field and maintained good removal performance (80 %) after five cycles. The degradation products were identified by applying LC-MS/MS, and possible degradation mechanisms and pathways were proposed. Finally, the antibacterial activity of intermediate products was evaluated using Escherichia coli, which revealed that the toxicity of TC was reduced effectively by the degradation of Lac@MMOF. Overall, Lac@MMOF is a green alternative for residual antibiotic removal in water.

Facile microwave-assisted synthesis of Sb2O3-CuO nanocomposites for catalytic degradation of p-nitrophenol

Recently, bimetallic nanocomposites have been prepared and used in the fields of sensing, catalysis, energy and medicine. However, there are few reports on the preparation and application of new antimony-metal nanocomposites based on two-dimensional antimonene (AM). Herein, Sb2O3-CuO nanocomposites were facilely synthesized by using microwave-assisted heating the mixture solution of AM and Cu2+ ions and utilized for catalytic degradation of p-nitrophenol (PNP). Interestingly, in the mixed solution of AM and various metal ions (Cu2+, Co2+, Mn2+), only the mixture of AM and Cu2+ ions showed efficient fading and absorption reduction effects on PNP after being heated. A series of characterization on morphology and elemental composition confirmed that the nanocomposites obtained after microwave heating was composed of Sb, Cu, O elements (namely Sb2O3-CuO), and was a layered structure loaded with numerous irregular particles. Compared with other catalysts, the nanocomposite has higher catalytic efficiency (the rate constant of 1.07 s−1), and was capable of degrading 96 % of PNP with only 3 s reaction. Electron spin resonance spectroscopy and liquid chromatography-mass spectrometry analysis demonstrated that the copper-mediated Fenton-like reaction in the nanocomposites induced hydroxyl radicals which can efficiently attack and degrade PNP. This study presents a novel approach to the synthesis of antimony-metal nanocomposites and provides a potential solution for the treatment of organic pollutants.

Structure modeling-based characterization of ChnD, the 6-hydroxyhexanoate dehydrogenase from Acinetobacter sp. strain NCIMB 9871

α,ω-Dicarboxylic acids, ω-aminoalkanoic acids, and α,ω-diaminoalkanes are valuable building blocks for the production of biopolyesters and biopolyamides. One of the key steps in producing these chemicals is the oxidation of ω-hydroxycarboxylic acids using alcohol dehydrogenases (e.g., ChnD of Acinetobacter sp. NCIMB 9871). However, the reaction and structural features of these enzymes remain mostly undiscovered. Thereby, we have investigated characteristics of ChnD based on enzyme kinetics, substrate-docking simulations, and mutation studies. Kinetic analysis revealed a distinct preference of ChnD for medium chain ω-hydroxycarboxylic acids, with the highest catalytic efficiency of 18.0 mM−1s−1 for 12-hydroxydodecanoic acid among C6 to C12 ω-hydroxycarboxylic acids. The high catalytic efficiency was attributed to the positive interactions between the carboxyl group of the substrates and the guanidino group of two arginine residues (i.e., Arg62 and Arg266) in the substrate binding site. The ChnD_R62L variant showed the increased efficiency and affinity, particularly for fatty alcohols (i.e., C6–C10) and branched-chain fatty alcohols, such as 3-methyl-2-buten-1-ol. Overall, this study contributes to the deeper understanding of medium-chain primary aliphatic alcohol dehydrogenases and their applications for the production of industrially relevant chemicals such as α,ω-dicarboxylic acids, ω-aminoalkanoic acids, and α,ω-diaminoalkanes from renewable biomass.

Reusable CS-Ca@PEI/CuMnO2 Hydrogel Beads for Peroxymonosulfate-Activated Degradation of Congo Red.

Metal oxides can activate peroxymonosulfate (PMS) for the catalytic degradation of organic dyes. However, achieving high catalytic efficiency, structural stability, ease of recovery, and recyclability remains challenging for both research and practical applications. To address these requirements, a bimetallic oxide, CuMnO2, was synthesized using a simple hydrothermal approach and was encapsulated to create hydrogel beads, CS-Ca@PEI/CuMnO2. Subsequently, CS-Ca@PEI/CuMnO2 was used to activate PMS and establish a solid-liquid heterogeneous oxidation system (CS-Ca@PEI/CuMnO2/PMS) for the degradation of Congo red (CR). The effects of various parameters such as different systems, catalyst dosages, initial pH values, PMS concentrations, temperatures, and anion types on the catalytic degradation properties of CS-Ca@PEI/CuMnO2 for CR were systematically evaluated. The results indicated that CS-Ca@PEI/CuMnO2 has exceptional degradation capacity, achieving 91.0% degradation of CR at pH 7. After three degradation cycles, the catalyst maintained an 86.9% degradation efficiency compared to its original performance, highlighting its robust structural stability. The presence of reactive radicals, specifically 1O2 and •O2-, were confirmed through quenching experiments, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance spectroscopy (EPR). Liquid chromatography-tandem mass spectrometry (LC-MS) revealed ten proposed intermediates in the catalytic degradation process. Due to its exceptional catalytic performance, structural durability, recyclability, and ease of retrieval, the catalyst shows great potential for effectively removing organic pollutants from industrial wastewater.

In Situ Synthesis, Characterization and Photocatalytic Efficacy of Silver-Enhanced MXene and Graphene Nanocomposites

The emergence of 2D materials has significantly expanded the wide range of nanomaterials with diverse applications. Notably, their high conductivity, catalytic efficiency, and hydrophobicity have fueled heightened research interests for water treatment applications. This research aimed to investigate the synthesis and characterization of MXene and reduced graphene oxide (rGO) nanocomposites with silver nanoparticles (Ag) for enhanced catalytic activity in the decomposition of Direct Blue-24 dye. In this study, we employed well-established methods, previously documented in the literature, to prepare two distinct nanocomposites. Novel nanocomposites, namely reduced graphene oxide–silver nanoparticles (rGO–Ag) and MXene–silver nanoparticles (MXene–Ag), were synthesized using the hydrothermal and direct reduction method with an ammoniacal solution (aqueous solution). Comprehensive characterization using advanced tools revealed that the introduced Ag particles integrated seamlessly onto the parent nanofilms of the Carbon derivatives, forming a secondary phase with enhanced catalytic functionality. These nanocomposites demonstrated significant improvements in the catalytic decomposition reactions in simulated wastewater. Verification involved the reduction reaction of Direct Blue-24 dye at known nanocomposite concentrations. The results indicated that MXene–Ag exhibited a superior catalytic activity of 98% in 10 min compared to the rGO–Ag nanocomposite films, which achieved 96% in 35 min. The results indicated that MXene–Ag nanocomposites exhibited a 20–25% increase in catalytic efficiency compared to the rGO–Ag nanocomposites. The outcomes of this research hold promise for practical applications in textile wastewater management and various industrial sectors dealing with mutagenic and carcinogenic chemicals containing azo and/or phthalocyanine products.

Bimetallic phosphidethe nanoparticles as photo-enhanced nanozymes for synergistic cancer immunotherapy

<p class="MsoNormal" style="margin-top: 12pt; text-align: justify;"><span lang="EN-US" style="font-family: 'times new roman', times, serif; font-size: 14pt;">Nanozyme with biomimetic enzyme activity has the advantages of good catalytic performance, high stability, and is not easily affected by temperature. However, the application of tumor microenvironment (TME) in the tumor is limited due to its low catalytic activity. Herein, a multifunctional nanozyme based on CuCoP with multivalent metal ions (Cu+/Cu2+ and Co2+/ Co3+) provides an innovative strategy for constructing acid-responsive cancer therapy. CuCoP has excellent photothermal properties (photothermal conversion efficiency of 66.9%) as well as glutathione (GSH) peroxidase activity and high photo-enhanced peroxidase-like (POD) enzyme activity in weak acid TME. CuCoP can consume the overexpressed GSH, thus alleviating the antioxidant capacity of the tumor, and reduces Cu2+/ Co3+ to Cu+/ Co 2+. Subsequently, the generated Cu+/Co2+ will react with endogenous H2O2 to generate cytotoxic hydroxyl radical (•OH), which have high catalytic efficiency in weakly acidic TME. Crucially, the synergistic effect of PTT and the cascade reaction of bimetallic atoms with GSH and H2O2 can effectively reduce antioxidant capacity, inhibit tumors and trigger effective immune cell death (ICD) process, which caused a strong immune response and inhibit tumor recurrence and metastasis. As a novel bimetallic sulfide nanoenzyme triggered by TME, CuCoP has great research value in cancer therapy.</span></p>

A photocatalytic redox cycle over a polyimide catalyst drives efficient solar-to-H2O2 conversion

Circumventing the conventional two-electron oxygen reduction pathway remains a great problem in enhancing the efficiency of H2O2 photosynthesis. A promising approach to achieve outstanding photocatalytic activity involves the utilization of redox intermediates. Here, we engineer a polyimide aerogel photocatalyst with photoreductive carbonyl groups for non-sacrificial H2O2 production. Under photoexcitation, carbonyl groups on the photocatalyst surface are reduced, forming an anion radical intermediate. The produced intermediate is oxidized by O2 to produce H2O2 and subsequently restores the carbonyl group. The high catalytic efficiency is ascribed to a photocatalytic redox cycle mediated by the radical anion, which not only promotes oxygen adsorption but also lowers the energy barrier of O2 reduction reaction for H2O2 generation. An apparent quantum yield of 14.28% at 420 ± 10 nm with a solar-to-chemical conversion efficiency of 0.92% is achieved. Moreover, we demonstrate that a mere 0.5 m2 self-supported polyimide aerogel exposed to natural sunlight for 6 h yields significant H2O2 production of 34.3 mmol m−2.

Next-generation of a Fe-Ce double variable-valence metals modulated high-efficiency nanozyme

High catalytic efficiency is the continuous pursuit for the preparation of high-performance nanozymes. In this work, a Fe-Ce double variable-valence metals nanozyme (Fe-Ce-MOL) was constructed based on metal–organic layers (MOLs), a class of two-dimensional metal–organic frameworks with ultra-thin structure, for peroxidase (POD) mimicking. Fe-Ce-MOL exhibited significantly enhanced catalytic activity in comparison with that of natural horseradish peroxidase and single variable-valence metal nanozyme (Fe-Zr-MOL). Density functional theory calculations demonstrated that the Fe site of Fe-Ce-MOL had a stronger adsorption effect on H2O2 compared to Fe-Zr-MOL and more heat was released in the catalytic reaction of H2O2, making the reaction easier to occur. Moreover, there was more electron transfer between Fe and Ce double variable-valence metals, also accelerating the catalytic process. These results indicated that the ultra-thin structure of Fe-Ce-MOL provided more catalytic sites and Fe and Ce double variable-valence metals could regulate the process of oxidation–reduction and promote the efficiency of electron transfer synergistically. As a proof of concept, the proposed Fe-Ce-MOL was used in biosensing and antibacterial applications. These results suggested that Fe-Ce-MOL had great potential as a new-generation nanozyme. This work pioneers a new approach for the rational design of highly efficient nanozymes.

Visualizing Phase Evolution of Co2C for Efficient Fischer-Tropsch to Olefins.

Cobalt carbide (Co2C) possesses high catalytic efficiency Fischer-Tropsch synthesis (FTS), while the products selectivity appears sensitive to crystallography geometry. Since the Anderson-Schulz-Flory (ASF) distribution in FTS is broken through fabricating facetted Co2C nanocrystals, yet the underlying mechanism of Co2C crystallization remains unclarified suffering from sophisticated catalyst composition involving promoter agents. Herein, the synthesis of high-purity single-crystal nanoprisms (Co2C-p) for highly efficient FTS is reported to lower olefins. Through comprehensive microstructure analysis, e.g., high-resolution TEM, in situ TEM and electron diffraction, as well as finite element simulation of gas flow field, for the first time the full roadmap of forming catalytic active cobalt carbides is disclosed, starting from reduction of Co3O4 precursor to CoO intermediate, then carburization into Co2C-s and subsequent ripening growth into Co2C-p. This gas-induced engineering of crystal phase provides a new synthesis strategy, with many new possibilities for precise design of metal-based catalyst for diverse catalytic applications.

Silica nanospheres-encapsulated polymer ligands-bound Pd nanoparticles as highly efficient and selective catalysts for semi-hydrogenations of alkynes

In this work, we report that poly (acrylic acid) (PAA) and poly (ethylenimine) (PEI) capped Pd nanoparticles (NPs) encaged in hollow silica nanospheres (PAA/PEI-Pd@HSNs) function as highly efficient and selective catalysts for hydrogenations of a series of alkynes. We used the coordination of Pd4+ ions with PEI and PAA to build the micelles system in an ethanol-water system, which was employed as the templates for silica deposition and following NaBH4 reduction to give PAA/PEI-Pd@HSNs. The materials feature polymer-coordinated small Pd NPs inside silica nanospheres with thin shells and large cavities. The PAA/PEI-Pd@HSNs exhibit extremely high catalytic efficiency and reusability with enhanced alkene selectivity of ∼90 % at near complete conversions for hydrogenation of a series of alkynes, and maintain high selectivity even with a significantly extended reaction time. The enhanced catalytic performance of PAA/PEI-Pd@HSNs is ascribed to their thin silica shells/large cavities to improve the catalytic activity, PEI/PAA ligands that inhibit the deep hydrogenation of alkenes to alkanes on Pd NPs, and the protection of silica shells for inner ligands and Pd NPs to improve the reusability.

Synthesis of HZSM-5@activated carbon for improving aromatic production from catalytic pyrolysis of biomass

HZSM-5 widely used for the catalytic pyrolysis of biomass exhibits the drawbacks of high diffusion resistance and large coke production. To effectively enhance the catalytic efficiency and alleviate the coke deposition, a novel promising catalyst, HZSM-5 coated activated carbon (HZSM-5@AC), was prepared for the first time for in-line upgrading the pyrolysis products of soybean straw. Various catalysts including HZSM-5, activated carbon, and the HZSM-5@AC catalysts with different HZSM-5 to activated carbon mass ratios were characterized. The results showed that the HZSM-5 was successfully coated on the surface of activated carbon and the addition of activated carbon introduced a mesoporous structure and more acidic sites to the catalyst. The catalytic performance on the biomass conversion showed that the catalyst with HZSM-5-to-activated carbon mass ratio of 18:5 (18HZSM-5@5AC) had the highest catalytic efficiency on the conversion of biomass into aromatics with a selectivity of 99.5%, including 75.68% of benzene, toluene, and xylenes (BTX) with a yield of 74.68 mg/g. Moreover, a possible pathway for HZSM-5@AC catalyzed biomass pyrolysis was proposed through analyzing the conversion of model compounds. The catalyst cycling experiments demonstrated the higher stability of HZSM-5@AC than the parent HZSM-5 and activated carbon. TG, FTIR, Raman and SEM showed that the spent HZSM-5@AC was hardly structurally changed with a low coke yield of 0.08%. However, the spent HZSM-5 was partly structurally deactivated by large aromatic ring systems with a coke yield of 3.74%. SEM results also showed that a large amount of polymerized material encapsulated the surface of the spent HZSM-5.

Composite catalyst regenerated from spent Cu-Bi-spinel adsorbent and its Fenton-like photocatalysis mechanism for efficient removal of sulfamethoxazole

Reutilization of spent adsorbent by converting the adsorbed organic pollutants into carbon matrix has attracted more attention in recent years, which delivers a greener way for the preparation of catalysis and environment remediation. In this work, CuBi2O4 after adsorption of pollutant sulfamethazine was further transformed to a photocatalyst CBO-WC500 with high catalytic efficiency for degradation of typical pharmaceuticals. The XAFS analysis proved that Cu-C chemical bond was constructed during the preparation process. The obtained CBO-WC500 was applied to remove sulfamethoxazole (SMX) through photocatalytic Fenton-like reaction, and removal efficiency reached 88.9 % after 60 minutes with the initial 5 mg•L−1 SMX and 0.2 g•L−1 catalyst in peroxymonosulfate (PMS) system. The results showed that the introduction of carbon stem from waste improved separation of photo-generated carriers and electron transfer capability, thus more photo-induced electrons could participate in reaction with PMS. Moreover, Cu(I) and Cu(II) in CBO-WC500 with Cu-Bi-spinel structure played a vital role in PMS activation. Led by electron transportation, reactive species (1O2, •OH, SO4•-) originated from PMS contributed to degradation of SMX, and degradation pathway of target pollutant was proposed based on analysis of intermediates. Removal efficiency of CBO-WC500 for SMX kept stable after several cycles’ utilization, and it also showed decent eliminating performance of mixed pollutants in different water matrix. This study has provided a potential way for resource reuse of adsorbed pollutant and realizing reutilization of spent adsorbent as photocatalyst with higher efficiency.