Addition Of Catalyst Research Articles

In English

The main idea of this work is the investigation of structural and morphological characteristics of microcrystalline cellulose with switchgrass (Panicum virgatum L.) by the method of organo-solvent cooking with the addition of various brands of ion-exchange resins instead of sulfuric acid. A sulfonated copolymer of styrene and divinyl benzene with two functional groups per ring - Purolite CT-275 and a sulfonated copolymer based on tetrafluoroethylene - Nafion NR-50 were chosen as initial ion exchange resins. Air-dry switchgrass (Panicum virgatum L.), a technical culture, was used for the research. Microcrystalline cellulose (MCC) was obtained from it by the method of organo-solvent cooking with the addition of a solid catalyst. Using the methods of XRD, FTIR-ATR, AFM, TGA and DSC, the structure and morphology of MCC were studied. It is found that the use of ion-exchange resins in the organo-solvent method of obtaining MCC in a batch reactor requires the use of protective covers for the catalyst to avoid its mechanical damage. It has been found that only sulfonated copolymers based on tetrafluoroethylene are stable in the cooking solution, in contrast to sulfonated copolymers of styrene and divinylbenzene, and allow obtaining MCC from millet with a yield of 53 % versus 40 % for the classical method and a degree of polymerization of 440 versus 578, respectively. Due to the destruction of amorphous binders in the MCC’s from switchgrass (Panicum virgatum L.), regardless of the conditions of its production, we observe further ordering of the structure of the obtained MCC which is expressed in narrower and more intense peaks in the range 2θ = 22–23°. The FTIR-ATR method showed that the obtained MCC has functional groups similar to commercial M-1021. The AFM method showed that MCC has a globular and wavy relief. Surface roughness with globular relief is 12.6 nm.

Design, Development and Molecular Docking Studies of C-2 Sulfenylated Benzofurans: Potential Interleukin 1-β Antagonist

An environmental friendly methodology for C-2 sulfenylation of benzofurans through dehydrogenative cross-coupling has been developed. Sulfenylation at second position is carried out using commercially available thiols in presence of molecular iodine and DMSO. The reaction accommodates wide spectrum of electronically diverse substituents on thiophenol ring. This process offers diverse advantages, including greener reaction conditions, moderate to good percentage yields, easy workup, no additional metal catalysts requirement and gram scale synthesis. Molecular docking studies is also conducted to substantiate interleukin 1-β antagonist nature of the designed compounds.

Valorization of low heavy metal-accumulating plants through catalytic hydrothermal liquefaction with attapulgite: Product characterization and migration behavior of heavy metals

Harmless treatment of heavy metal-accumulating plants is significant for further development and application of phytoremediation for contaminated soil remediation. In this study, hydrothermal liquefaction (HTL) of low heavy metal-accumulating plants (Jute, Solanum nigrum, and Sorghum) was conducted at different temperatures (280–360 °C) for bio-oil production. Attapulgite and Co/Attapulgite were prepared and tested in HTL process. The maximum bio-oil yield and higher heating value (HHV) was found to be 32.04% and 29.61 MJ/kg from HTL of Solanum nigrum with Co/Attapulgite at 300 °C. The improvement in quality of bio-oil was marked with decreased O/C content (0.26) and newly formed hydrocarbon fraction with the content of 6.24% with Co/Attapulgite catalyst. It was beneficial for immobilization of Mn, Zn and Cr in hydrochar with addition of catalyst. Notably, Mn and Cd were not detected in any bio-oil, and the proportion of Cr in the bio-oil obtained at 360 °C decreased to zero with Co/Attapulgite. XPS and XRD analysis indicated that Mn and Zn existed in the form of Mn3O4, Mn, ZnO and Zn(OH)2 in hydrochar. Finally, potential pathway of heavy metals migration-transformation behaviors during HTL was proposed.

Recyclable ionic liquid-mediated synthesis of quinazolin-4(3H)-ones under metal-free and solvent-free conditions

A metal-free and solvent-free method for the synthesis of quinazolin-4(3H)-ones is proposed by condensation cyclization of 2-aminobenzamides and aldehydes using 1-butyl-3-methylimida-zolium tetrafluoride ([Bmim]BF4) as ionic liquid catalyst. In this reaction, [Bmim]BF4 acts as both a catalyst and a solvent without need for additional catalysts and solvents. This method exhibits favorable functional group tolerance in substrates and affords a series of desired products in moderate to excellent yields. In addition, it is noteworthy that the reaction yield is still as high as 87% after [Bmim]BF4 is recycled at least four times.

Catalytic pyrolysis of FeAlOx and medical plastic waste: Kinetic, slag conversion, and gas emission patterns

The globally substantial increase in medical waste stream and types renders efficient disposal and circularity strategies imperative. Currently, most medical waste disposed of is predominantly plastic materials. A promising approach for its recycling efficiency involves using catalytic pyrolysis to transform plastic waste into reusable pyrolysis oil. This study aimed to characterize gas products and bottom slag of the catalytic pyrolysis of medical waste infusion tubes (PVC) via thermogravimetric (TG) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) analyses. As s bimetallic catalyst known for its exceptional ability as a carbon carrier that can turn carbon into CO at high pyrolysis temperatures, FeAlOx was synthesized and characterized. The addition of 50% (wt) FeAlOx yielded the lowest activation energy (Eα = 108.11 kJ/mol). The catalyst facilitated the breaking of the C-Cl bond in PVC, increasing HCl and light hydrocarbon gases, such as CH4. Prolonged pyrolysis residence times reduced chlorine remnants in the bottom slag, increased its alumina content, and achieved a stable slag composition. The reaction model with varying catalyst additions was dynamically evolved as follows: F1.6→F2→F2.2→F1.5 in the first stage and F2.3→F2.8→F4.8→F2 in the second stage, thus achieving an optimal kinetic and thermodynamic ratio of 5:5. The addition of the catalyst reduced not only the energy consumption and complexity of the two pyrolysis stages of PVC but also the production of pollutants, thus improving the circularity. This study provides actionable insights into the potential of the catalyst-assisted pyrolysis as an effective method for the circular management of medical waste.

Catalytic co-pyrolysis of Vachellia Farnesiana with polypropylene plastic to produce bio-oil: Parameter optimization study

Catalytic co-pyrolysis of biomass Vachellia Farnesiana (VF) and Polyropylene (PP) plastic was carried out using sodium carbonate (Na2CO3) catalyst to produce high quality oil. A semi batch pyrolysis reactor was used to perform the co-pyrolysis of VF and PP at different temperatures (350–550 °C), time (20-60mins), VF/PP ratio (0–100 %) and catalyst loading (0–10 %). The experiments were conducted using 40 g feed mixture to optimize the feed ratio, temperature, reaction time, and Na2CO3 catalyst ratio. The best conditions for the process were thus found to be 450 °C temperature, 40 min time, and 5 wt% Na2CO3 catalyst. Under these conditions, the maximum fuel oil yield of ∼ 64 % was achieved, which was approximately 4 % higher than oil yield obtained without utilization of Na2CO3 catalyst. Variations in temperature, the VF/PP ratio, and the Na2CO3 catalyst parameters had the most significant effects on improving the quality of the oil. The utilization of Na2CO3, along with an increase in temperature and the amount of PP in the VF/PP blend, contributed to higher yields and a greater gross calorific value (GCV) of the obtained oil. FTIR analysis was conducted to identify the functional groups present in the oil. Similarly, GCMS analysis further revealed that the presence of a significant alkanes and alkenes, along with fewer oxygenates, was responsible for the favorable GCV of the oil. The addition of the Na2CO3 catalyst was found to increase the concentrations of alkanes, alkenes, and alcohols, while reducing acids, ethers, and ketones. As a result, it was able to enhance the quality of the oil.

Advanced oxidation of polycyclic aromatic hydrocarbons in tropical soil: Self-catalytic utilization of natural iron contents in an oxygenation reactor supported with persulfate

The catalysts derived from natural iron minerals in the advanced oxidation process offer several advantages. However, their utilization in soil remediation is restricted due to the presence of soil impurities, which can inhibit the catalytic activity of these minerals. The soils in tropical regions exhibit lower organic matter content, limited cation exchange capacity, and are non-saline, this enhances the efficiency of utilizing natural iron minerals from tropical soil as a catalyst. In this regard, the catalytic potential of naturally iron-bearing tropical soil was investigated to eliminate phenanthrene (PHE), pyrene (PYR), and benzo[α]pyrene (B[α]P) using an oxygenated reactor supported with persulfate (PS). The system showed an efficient performance, and the removal efficiencies under the optimum conditions were 81 %, 73 %, and 86 % for PHE, PYR, and B[α]P, respectively. This indicated that the catalytic activity of iron was working efficiently. However, there were changes in the soil characteristics after the remediation process such as a significant reduction in iron and aluminum contents. The scavenging experiments demonstrated that HO• had a minor role in the oxidation process, SO4•− and O2•− emerged as the primary reactive species responsible for the effective degradation of the PAHs. Moreover, the by-products were monitored after soil remediation to evaluate their toxicity and to propose degradation pathways. The Mutagenicity test showed that two by-products from each PHE and B[α]P had positive results, while only one by-product of PYR showed positive. The toxicity tests of oral rat LD50 and developmental toxicity tests revealed that certain PAHs by-products could be more toxic from the parent pollutant itself. This study represents a notable progression in soil remediation by providing a step forward in the application of the advanced oxidation process (AOP) without requiring additional catalysts to activate oxidants and degrade pollutant PAHs from the soil.

High-Fidelity RNA Copying via 2',3'-Cyclic Phosphate Ligation.

Templated ligation offers an efficient approach to replicate long strands in an RNA world. The 2',3'-cyclic phosphate (>P) is a prebiotically available activation that also forms during RNA hydrolysis. Using gel electrophoresis and high-performance liquid chromatography, we found that the templated ligation of RNA with >P proceeds in simple low-salt aqueous solutions with 1 mM MgCl2 under alkaline pH ranging from 9 to 11 and temperatures from -20 to 25 °C. No additional catalysts were required. In contrast to previous reports, we found an increase in the number of canonical linkages to 50%. The reaction proceeds in a sequence-specific manner, with an experimentally determined ligation fidelity of 82% at the 3' end and 91% at the 5' end of the ligation site. With splinted oligomers, five ligations created a 96-mer strand, demonstrating a pathway for the ribozyme assembly. Due to the low salt requirements, the ligation conditions will be compatible with strand separation. Templated ligation mediated by 2',3'-cyclic phosphate in alkaline conditions therefore offers a performant replication and elongation reaction for RNA on early Earth.

Temperature, pressure, and duration impacts on the optimal stiffening of carbonates aged in diammonium phosphate solution

Diammonium phosphate (DAP) has been proven effective in improving the stiffness of weak or acid-damaged carbonates, thereby preserving hydraulic fracture conductivity. The reaction between DAP and calcite in chalk formations primarily produces hydroxyapatite (HAP), which is stiffer than calcite. However, the optimal reaction outcomes vary greatly with factors such as DAP concentration and reaction conditions. This study investigated the DAP-calcite reaction duration, pressure, and temperature effects on the stiffness magnitude of soft Austin chalk. Also, the catalyst effect and depth of HAP formation were examined. The study involved the assessment of stiffness non-destructively (impulse hammering), mineralogy (XRD, SEM), and elemental composition (XRF). The study tested 15 different DAP-chalk reaction variations, where the pressure, temperature, aging time and catalyst addition were modified in each case. The samples' elastic stiffness distributions were then collected and compared to the pre-reaction ones. The results showed that the elastic stiffness increased in all treated samples, with an 181% maximum increase achieved after 72 h at 6.9 MPa and 75 °C. However, the pressure effect was minor compared to the temperature. The SEM images revealed different HAP morphology corresponding to different treatment conditions. Although the treated samples showed an increased intensity of phosphorus throughout the entire sample, the near-surface zone (4–6 mm) was the most affected, as inferred from the XRF elemental analysis. The study's findings can help optimize hydraulic fracturing operations in weak carbonate reservoirs, improving production rates and overall well performance.

DFT Mechanistic Investigation into Ni(II)-Catalyzed Hydroxylation of Benzene to Phenol by H2O2.

Introduction of oxygen into aromatic C-H bonds is intriguing from both fundamental and practical perspectives. Although the 3d metal-catalyzed hydroxylation of arenes by H2O2 has been developed by several prominent researchers, a definitive mechanism for these crucial transformations remains elusive. Herein, density functional theory calculations were used to shed light on the mechanism of the established hydroxylation reaction of benzene with H2O2, catalyzed by [NiII(tepa)]2+ (tepa = tris[2-(pyridin-2-yl)ethyl]amine). Dinickel(III) bis(μ-oxo) species have been proposed as the key intermediate responsible for the benzene hydroxylation reaction. Our findings indicate that while the dinickel dioxygen species can be generated as a stable structure, it cannot serve as an active catalyst in this transformation. The calculations allowed us to unveil an unprecedented mechanism composed of six main steps as follows: (i) deprotonation of coordinated H2O2, (ii) oxidative addition, (iii) water elimination, (iv) benzene addition, (v) ketone generation, and (vi) tautomerization and regeneration of the active catalyst. Addition of benzene to oxygen, which occurs via a radical mechanism, turns out to be the rate-determining step in the overall reaction. This study demonstrates the critical role of Ni-oxyl species in such transformations, highlighting how the unpaired spin density value on oxygen and positive charges on the Ni-O• complex affect the activation barrier for benzene addition.

Synergistic interactions between cellulose and plastics (PET, HDPE, and PS) during CO2 gasification-catalytic reforming on Ni/CeO2 nanorod catalyst

CO2 gasification-reforming is a promising approach for the transformation of carbonaceous materials into CO-rich syngas. Within municipal solid waste and agricultural waste streams, plastics are commonly found intermixed with biomass waste. This study delves into the CO2 gasification-reforming of biomass (cellulose) and various plastics (PET, HDPE, and PS) using a self-built online weighing fixed bed reactor and a two-stage fixed bed reactor. During the gasification-reforming of cellulose-plastic mixtures without the catalyst, the experimental gas production rate of cellulose slightly decreased, with the peak of gas production migrating to a higher temperature range. This phenomenon can be attributed to the molten plastic adhering to the cellulose surface, which impeded heat and mass transfer essential for cellulose decomposition. Furthermore, the gas production from plastics was suppressed in the mixtures, likely due to the interference of cellulose char in the decomposition of plastics. The incorporation of 2%Ni/CeO2 catalysts not only augmented gas yields and production rates but also emphasized the synergistic interactions. For the cellulose-HDPE mixture, the total gas yield was reduced by 14.9 mmol gsample−1 relative to the theoretical value. Given that HDPE possessed the highest decomposition temperature, the synergistic interaction was predominantly driven by the inhibitive nature of cellulose char. In contrast, the total gas yields for cellulose-PET and cellulose-PS mixtures increased by 8.7 mmol gsample−1 and 13.3 mmol gsample−1, respectively. The free radicals emanating from cellulose could trigger the decomposition of volatile components from plastics. Concurrently, the decomposition products of plastic could serve as hydrogen donors to stabilize the volatiles of cellulose. The interactions primarily affect the volatiles and tar components of the mixtures. The catalysts amplified gas yields by facilitating the CO2 reforming of tar, therefore, the synergistic interaction became evident upon catalyst addition. Gas chromatography-mass spectrometry analyses of the tar also corroborated the described interaction mechanisms between cellulose and plastics. Thermogravimetric analysis of used catalysts indicated that the synergistic action between cellulose and plastic could effectively diminish coke deposition, thereby preventing swift catalyst deactivation.

Evaluation of biomass sources on the production of biofuels from lignocellulosic waste over zeolite catalysts

Catalytic fast pyrolysis (CFP) is a promising method to convert biomass waste into sustainable bio-oils. However, the relationship gap between biomass characteristics and bio-oil quality has hindered the development of CFP technology. This study investigated the pyrolysis and CFP of ten biomass sources over zeolites, and showed that biomass sources and zeolites played important roles in bio-oil production. For noncatalytic trials, the bio-oil yield was positively related to holocellulose (R2 = 0.75) and volatiles content (R2 = 0.62) but negatively to ash content (R2 = -0.65). The bio-oil quality was dramatically improved after catalyst addition. For CFP over ZSM-5, hydrocarbons selectivity of bio-oils was increased by 1.6∼79.3 times, which was closely related to H/C ratio (R2 = 0.79). For ZSM-5@SBA-15 trials, the dependency of hydrocarbons selectivity on biomass characteristics was less clear than that in ZSM-5 counterparts, although undesirable PAHs were inhibited for most biomass sources. This study demonstrated the influence mechanism of biomass characteristics on bio-oil compositions.

Chiral Covalent Organic Cages: Structural Isomerism and Enantioselective Catalysis.

Covalent organic cages are a prominent class of discrete porous architectures; however, their structural isomerism remains relatively unexplored. Here, we demonstrate the structural isomerism of chiral covalent organic cages that renders distinct enantioselective catalytic properties. Imine condensations of tetra-topic 5,10-di(3,5-diformylphenyl)-5,10-dihydrophenazine and ditopic 1,2-cyclohexanediamine produce two chiral [4 + 8] organic cage isomers with totally different topologies and geometries that depend on the orientations of four tetraaldehyde units with respect to each other. One isomer (PN-1) has an unprecedented Johnson-type J26 structure, whereas another (PN-2) adopts a tetragonal prismatic structure. After the reduction of the imine linkages, the cages are transformed into two amine bond-linked isomers PN-1R and PN-2R. After binding to Ni(II) ions, both can serve as efficient catalysts for asymmetric Michael additions, whereas PN-2R affords obviously higher enantioselectivity and reactivity than PN-1R presumably because of its large cavity and open windows that can concentrate reactants for the reactions. Density-functional theory (DFT) calculations further confirm that the enantioselective catalytic performance varies depending on the isomer.

Integrated Wastewater Processing using Electrogoagulation Method into Oxyhydrogen (HHO) for Renewable Energy

Integrated wastewater is one of the contributors to wastewater that can harm the environment, thus fast industrial expansion must be followed with advancements in wastewater processing systems. Because the presence of contaminants in integrated wastewater can cause several issues for persons and the environment, integrated wastewater processing is required. One type of integrated wastewater processing is the production of hydrogen gas as a new and sustainable energy source. The electrocoagulation process may be used to convert integrated wastewater into hydrogen gas. One type of integrated wastewater processing is the production of hydrogen gas as a new and sustainable energy source. The electrocoagulation process may be used to convert integrated wastewater into hydrogen gas. In this study, oxyhydrogen (HHO) was produced from integrated wastewater utilizing two process stages: integrated wastewater processing with an electrocoagulator, followed by the process of getting HHO using an oxyhydrogen reactor. A NaOH catalyst was applied at different concentrations of 0.1 M, 0.2 M, 0.3 M, 0.4 M, and 0.5 M with an electrolysis period of 5 minutes to produce hydrogen gas. The addition of the NaOH catalyst is intended to find the optimal concentration for the production of hydrogen gas. According to the findings of the study and analysis, the optimal NaOH catalyst concentration for producing hydrogen gas is 0.5 M with hydrogen content of 346 mg/m3

Zinc Chloride as a Catalyst in Hydrothermal Carbonization of Cocoa Pods Husk

In this study, we have successfully synthesized a high surface area of activated carbons (ACs) from cocoa pod husk (CPH) by using a combination of hydrothermal carbonization (HTC) and chemical activation in the presence of ZnCl2 as both of catalyst as well as activating agent. During HTC, the effect of HTC temperature (200 and 225 °C) and ZnCl2 to biomass mass ratio (1:1, 2:1, 3:1) as a catalyst to the characteristics of the obtained hydrochar (HC) and ACs were investigated. The obtained hydrochar (HCs) was then processed by using ZnCl2 chemical activation with a fixed HC to ZnCl2 mass ratio of 1:4 and the mixture was pyrolyzed at 600 °C for 1 h under an inert atmosphere. The results showed that the addition of catalyst during HTC presented different AC morphology, where the carbon samples were decorated with carbon microspheres. An increase of surface area was observed, where the ACs synthesized from catalyzed HC at biomass to ZnCl2 ratio of 1:3 at temperature 200 °C gave a higher surface area of 1954 m2/g compared to that of without catalyst (1165 m2/g). The catalysis effect was more profound at the HTC temperature of 200 °C compared to 225 °C, as reflected in the significant increase of AC surface area. The addition of a catalyst creates ACs with narrow pore distribution compared to that of synthesized in the absence of a catalyst. It was also observed that the ACs from catalyzed hydrochar possessed higher oxygenated functional groups (OFG) than those without catalysts.

Geometrical Stabilities and Electronic Structures of Ru3 Clusters on Rutile TiO2 for Green Hydrogen Production.

In response to the vital requirement for renewable energy alternatives, this research delves into the complex interactions between ruthenium (Ru3) clusters and rutile titanium dioxide (TiO2) (110) interfaces, with the aim of enhancing photocatalytic water splitting processes to produce environmentally friendly hydrogen. As the world shifts away from traditional fossil fuels, this study utilizes the density functional theory (DFT) and the HSE06 hybrid functional to thoroughly assess the geometric and electronic properties of Ru3 clusters on rutile TiO2 (110) surfaces. Given TiO2's renown role as a photocatalyst and its limitations in visible light absorption, this research investigates the potential of metals like Ru to serve as additional catalysts. The results indicate that the triangular Ru3 cluster exhibits exceptional stability and charge transfer effectiveness when loaded on rutile TiO2 (110). Under ideal adsorption scenarios, the cluster undergoes oxidation, leading to subsequent changes in the electronic configuration of TiO2. Further exploration into TiO2 surfaces with defects shows that Ru3 clusters influence the creation of oxygen vacancies, resulting in a greater stabilization of TiO2 and an increase in the energy required for creating oxygen vacancies. Moreover, the attachment of the Ru3 cluster and the creation of oxygen vacancies lead to the emergence of polaronic and hybrid states centered on specific titanium atoms. These states are vital for enhancing the photocatalytic performance of the material within the visible light spectrum. This DFT study provides essential insights into the role of Ru3 clusters as potential supplementary catalysts in TiO2-based photocatalytic systems, setting the stage for practical experiments and the development of highly efficient photocatalysts for sustainable hydrogen generation. The observed effects on electronic structures and oxygen vacancy generation underscore the intricate relationship between Ru3 clusters and TiO2 interfaces, offering a valuable direction for future research in the pursuit of clean and sustainable energy solutions.

Catalytic pyrolysis of lignocellulosic and algal biomass using NaOH as a catalyst

AbstractIn this work, the pyrolysis of barley straw (BS) and brown algae (BA) mixed with NaOH as a catalyst was compared. Four different catalyst‐to‐biomass mass ratios (i.e., 6:100, 8:100, 10:100, and 12:100) and five pyrolysis heating rates were examined. The kinetic parameters (e.g., the activation energy and pre‐exponential factor) were evaluated using the Friedman method and kinetic models. For noncatalytic pyrolysis, the average activation energies for BS and BA samples were 139.71 and 183.19 kJ mol−1, respectively. However, the addition of catalyst generally increased the average activation energy of BS samples but decreased that of BA samples. The enthalpy change and Gibbs free energy change revealed that both catalytic and noncatalytic pyrolysis processes were nonspontaneous and endothermic, and the inclusion of catalyst increased the average entropy change of the BS samples but decreased that of the BA samples. Char and biochar yields after pyrolysis were also analyzed quantitatively. These observations provide insight into the differences in catalytic pyrolysis between lignocellulosic and algal biomass species.

Is catalytic ozonation always an efficient treatment for refractory pollutant in various water matrices?

In this study, surrogate indicators (·OH yield and Rct value) were developed to identify whether homogeneous and heterogeneous catalysts should be added during ozonation of refractory pollutants. The abatement of atrazine (ATZ) was in the order of O3/H2O2 process (94 %) > O3/γ-Al2O3 process (70 %) > ozonation alone process (55 %) in synthetic water samples at pH 7, which was in agreement with the order of ·OH yield and Rct value. However, the abatement of ATZ during ozonation alone process (0.64–0.62) was higher than O3/H2O2 process (0.63–0.60) and O3/γ-Al2O3 process (0.48–0.49) in the presence of high dosage of humic acid (HA, 3.38 × 10−1–4.50 × 10−1 mg C/L) at pH 7. The abatement of ATZ was linearly proportional to ·OH yield, whereas it was not linearly proportional to Rct value in the synthetic water samples containing HA at pH7. The abatement of ATZ during ozonation alone process was higher than that during catalytic ozonation process by one-time ozone dosing method in real water. The abatement of ATZ during O3/H2O2 process and O3/γ-Al2O3 process were higher than that during ozonation alone process by three-time ozone dosing method in real water, which was linearly proportional to ·OH yield and Rct value. The residual DOM in phase III become recalcitrant to ozone, which could be decomposed by catalyst forming ·OH. Overall, this result implies that the comparison of ·OH yield and Rct value between ozone decay by DOM in various water matrices and by catalyst should be concerned before the addition of catalyst during ozonation process was applied in real water.

Nucleophilic functionalization of thianthrenium salts under basic conditions.

In recent years, S-(alkyl)thianthrenium salts have become an important means of functionalizing alcohol compounds. However, additional transition metal catalysts and/or visible light are required. Herein, a direct thioetherification/amination reaction of thianthrenium salts is realized under metal-free conditions. This strategy exhibits good functional-group tolerance, operational simplicity, and an extensive range of compatible substrates.

Regulation of Ni valence state and synergistic effects of supports in the hydrodeoxygenation of lignin-derived vanillin using pseudoboehmite-supported Ni catalysts

ABSTRACT Preparing 2-methoxy-4-methylphenol (MMP) through the vanillin (VAN) route is a crucial step in the high-value utilization of lignin (VTM). In this study, a series of Ni/PB catalysts were synthesized using pseudoboehmite (PB) as a carrier. Changes in the valence states of Ni were induced through H2 activation, while the impacts of reaction temperature, initial pressure, and catalyst addition were investigated based on the VTM process. The results revealed that PB exhibited a distinct mesoporous structure (average pore size of 5.8 nm), with Ni loaded in small particles size (3.88 nm). Ni species on the catalyst existed in a + 2-valence state, undergoing a change after H2 activation, with an increase in Ni0 promoting enhanced activity. The Ni/PB-450 catalyst exhibited excellent activity at 250°C for 3 hours (VAN conversion and MMP selectivity > 99%), and the catalyst demonstrated good durability, maintaining 99.1% VAN conversion and 80% MMP selectivity after two cycles. Combining the characterization and experimental results, the etherification and hydrogenation of VAN were identified as the primary reaction pathways. This study aimed to provide a new avenue for the high-value utilization of lignin and its derivatives through controlled catalyst preparation.