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We developed a series of heteropolyacid-modified lignin-MOF derived bimetallic catalyst for the efficient in situ hydrogenation/hydrodeoxygenation of biomass-derived 5-hydroxymethylfurfural using isopropanol as hydrogen-donating solvent. [Display omitted] Catalytic conversion of biomass-derived value-added chemicals was of great significance for the utilization of renewable biomass resources to instead of fossil chemicals. Biomass-derived lignin was regarded as an important support and 5-hydroxymethylfurfural (HMF) was a vital platform chemical derived from cellulose. Herein, a series of lignin-MOF hybrid catalysts were prepared and modified with different heteropolyacids (HPAs), which were then successfully introduced into the selective conversion of HMF to 5-hydroxymethylfurfuryl alcohol (MFA). The effect of different HPA, calcination temperature, etc. were all studied, and all catalysts were well characterized. It was confirmed that silicotungstic acid modified catalyst (Ni 3 Co-MOF-LS@HSiW) exhibited the best catalytic performance, while the highest conversion of HMF was up to 100%, with the best MFA yield of 86.5%. The finding in this study could provide novel insights for the utilization of lignin and preparation of value-added biomass-derived chemicals. [ABSTRACT FROM AUTHOR]

This study explores the use of sebacic acid, a catalyst not previously examined in the literature, for hydrogen production from NaBH4 through methanolysis and ethanolysis reactions. Solutions of sebacic acid with concentrations ranging from 0.1 M to 0.4 M were prepared and tested. At a concentration of 0.3 M, 90% of the hydrogen from a 0.33 M NaBH4 solution was released within 3 s, and full release was achieved in 4 s. Hydrogen production rates reached 4500 mL/min for ethanolysis and 4845 mL/min for methanolysis, with methanolysis reactions proving faster. The activation energies for methanolysis and ethanolysis were calculated as 7.17 kJ/mol and 52.3 kJ/mol, respectively. These results demonstrate that sebacic acid enables rapid and efficient hydrogen production, offering a new approach that significantly advances current hydrogen production methods. [ABSTRACT FROM AUTHOR]

Furfural has become one of the most promising building blocks directly derived from biomass. It can be transformed into numerous important biobased chemicals. Among them, furfuryl ethers such as furfuryl ethyl ether (FEE) and tetrahydrofurfuryl ethyl ether (THFEE) are considered to be attractive derivatives, notably as fuel components, due to their high stability and high octane numbers. Therefore, the production of furfuryl ethers from furfural via a hydrogenation route is an important academic and industrial challenge and requires the deployment of new catalytic processes under green and competitive reaction conditions. The existing processes are based on a two-step process combining hydrogenation and reaction with a strong Bronsted acid catalyst in batch conditions. For the first time, a continuous flow one-step process has been elaborated for the conversion of furfural directly into furfuryl ethers based on reductive etherification. The present work explores the catalytic performance in a continuous flow of commercial palladium catalysts supported on activated carbon for the catalytic reductive etherification of furfural with ethanol in the presence of trifluoroacetic acid. The chemical and engineering aspects, such as the mechanisms and reaction conditions, will be discussed. [ABSTRACT FROM AUTHOR]

Biodiesel has received tremendous attention as a sustainable energy source. This review presents an overview of various catalysts utilized in biodiesel production and compares their potential for producing biodiesel. Presented here are the excellent features of the various catalysts while highlighting their drawbacks. For instance, production of biodiesel with homogeneous base catalysts is easy but it can only be used with refined oils having low levels of free fatty acid (FFAs). When homogeneous acid is used in esterification, it causes reactor corrosion. Water and FFAs do not affect heterogeneous acid catalysts. Thus, transesterification of triglycerides into biodiesel and converting FFAs into biodiesel through esterification can be catalyzed more efficiently using a heterogeneous acid catalyst. Biocatalysts are also being used to produce biodiesel from oils with high FFAs. However, heterogeneous acid catalysts and biocatalysts are not suitable for industrial application due to serious mass transfer limitations. Biodiesel yield and conversion were compared over various catalysts in this paper. Also presented are the effects of different reaction parameters on biodiesel yield over different catalysts. The correct interplay of factors like reaction temperature, time, alcohol-to-oil molar ratio, and catalyst loading produces optimal process conditions that give the highest biodiesel yield. [ABSTRACT FROM AUTHOR]

A series of 3-aryl-8-nitro[1,2,4]triazolo[3,4-b][1,3,4]benzothiadiazepines have been synthesized by refluxing 4-amino-5-aryl-1,2,4-triazole-3-thiols and 5-nitro-2-chlorobenzaldeyde in methanol in the presence of glacial acetic acid as catalyst. The structure of the synthesized compounds was confirmed by spectral data, and their fungicidal activity against four fungal strains (Aspergillus niger, Helminthosporium oryzae, Rhizoctonia solani, and Penicillium citrinum) was evaluated. The drug likeness analysis and molecular docking were performed using Swiss ADME, Chimera, and AutoDock Vina tools. [ABSTRACT FROM AUTHOR]

A new catalytic one-pot synthesis of N-substituted β-amido carbonyl compounds has been developed using bismuth nitrate as highly efficient, commercially available, recyclable, and reusable acid catalyst. The efficiency of the proposed protocol was demonstrated by 17 examples including various functionalized N-substituted β-amido carbonyl compounds. The reaction utilized easily available and cost-effective starting materials and proceeded at room temperature in a short period of time, followed by aqueous workup. [ABSTRACT FROM AUTHOR]

Reaction of 9-fluorene propargylic alcohols and substituted-2-hydrazinopyridine using BF3·OEt2 as a Lewis acid catalyst afforded 9-fluorenlidene appended 2-hydrazinopyridine imine derivatives has been developed. The scope of the reaction is demonstrated by selecting a range of fluorene propargylic alcohols and substituted 2-hydrazinopyridine imines. All the synthesized molecules were characterized using various spectroscopic and analytical techniques including 1H NMR,13C NMR, and Mass spectrometry. A plausible reaction mechanism for forming title compounds via propargylic allenyl carbocation is postulated. The synthetic utility of products thus formed is demonstrated by utilizing Suzuki coupling. [ABSTRACT FROM AUTHOR]

Diisoamyl (1R,4S)-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate (2) was prepared by reacting exo-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (1) with isoamyl alcohol in the presence of a sulfuric acid catalyst under sonication conditions. Compound 2 was characterized by 1H, 13C NMR, DEPT-135, infrared, and UV-vis spectroscopy. Gas chromatography–mass spectrometry, elemental analysis, and melting point determination were used to assess purity. The structure of compound 2 was also determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P21/c (14) with cell values of a = 15.5647(3) Å, b = 12.8969(2) Å, c = 9.0873(2) Å; β= 99.3920(10)°. [ABSTRACT FROM AUTHOR]

In the present study, an acid catalyst (UiO-66-SO3H) with Brønsted and Lewis acid sites was synthesised for the preparation of highly efficient biodiesel from oleic acid and methanol using chlorosulphonic acid sulfonated metal–organic frameworks (UiO-66) prepared with acetic acid as a moderator. The prepared catalysts were characterised using XRD, SEM, FT-IR and BET. The catalytic efficiency of the sulfonated catalysts was significantly improved and successful sulfonation was demonstrated by characterisation techniques. Biodiesel was synthesised by the one-pot method and an 85.0% biodiesel yield was achieved under optimum conditions of the reaction. The esterification reaction was determined to be consistent with a proposed primary reaction and the kinetics of the reaction was investigated. A reusability study of the catalyst (UiO-66-SO3H) was also carried out with good reproducibility. In conclusion, the present study provides some ideas for the synthesis of catalysts with high catalytic activity for the application in the catalytic preparation of biodiesel. [ABSTRACT FROM AUTHOR]

Solketal, a widely used glycerol-derived solvent, can be efficiently synthesized through heterogeneous catalysis, thus avoiding the significant product losses typically encountered with aqueous work-up in homogeneous catalysis. This study explores the catalytic synthesis of solketal using solid acid catalysts derived from recovered carbon blacks (rCBs), which are obtained through the pyrolysis of end-of-life tires. This was further converted into solid acid catalysts through the introduction of acidic functional groups using concentrated H2SO4 or 4-benzenediazonium sulfonate (BDS) as sulfonating agents. Additionally, post-pyrolytic rCB treated with glucose and subsequently sulfonated with sulfuric acid was also prepared. Comprehensive characterization of the initial and modified rCBs was performed using techniques such as elemental analysis, powder X-ray diffraction, thermogravimetric analysis, a back titration method, and both scanning and transmission electron microscopy, along with X-ray photoelectron spectroscopy. The catalytic performance of these samples was evaluated through the batch mode glycerol acetalization to produce solketal. The modified rCBs exhibited substantial catalytic activity, achieving high glycerol conversions (approximately 90%) and high solketal selectivity (around 95%) within 30 min at 40 °C. This notable activity was attributed to the presence of -SO3H groups on the surface of the functionalized rCBs. Reusability tests indicated that only rCBs modified with glucose demonstrated acceptable catalytic stability in subsequent acetalization cycles. The findings underscore the potential of utilizing end-of-life tires to produce effective acid catalysts for glycerol valorization processes. [ABSTRACT FROM AUTHOR]

In view of the flue gas characteristics of cement kilns in China, the development of low-temperature denitrification catalysts with excellent anti-poisoning performance has important theoretical and practical significance. In this work, a series of MnCeOx@TiO2 and tourmaline-containing MnCeOx@TiO2-T catalysts was prepared using a chemical pre-deposition method. It was found that the MnCeOx@TiO2-T2 catalyst (containing 2% tourmaline) exhibited the best low-temperature NH3-selective catalytic reduction (NH3-SCR) performance, yielding 100% NOx conversion at 110 °C and above. When 100–300 ppm SO2 and 10 vol.% H2O were introduced to the reaction, the NOx conversion of the MnCeOx@TiO2-T2 catalyst was still higher than 90% at 170 °C, indicating good anti-poisoning performance. The addition of appropriate amounts of tourmaline can not only preferably expose the active {001} facets of TiO2 but also introduce the acidic SiO2 and Al2O3 components and increase the content of Mn4+ and Oα on the surface of the catalyst, all of which contribute to the enhancement of reaction activity of NH3-SCR and anti-poisoning performance. However, excess amounts of tourmaline led to the formation of dense surface of catalysts that suppressed the exposure of catalytic active sites, giving rise to the decrease in catalytic activity and anti-poisoning capability. Through an in situ DRIFTS study, it was found that the addition of appropriate amounts of tourmaline increased the number of Brønsted acid sites on the catalyst surface, which suppressed the adsorption of SO2 and thus inhibited the deposition of NH4HSO4 and (NH4)2HSO4 on the surface of the catalyst, thereby improving the NH3-SCR performance and anti-poisoning ability of the catalyst. [ABSTRACT FROM AUTHOR]

Bagasse and straw are the two feedstocks used to produce cellulosic ethanol from sugarcane. Although this technology is advancing commercially, the differentiation between bagasse and straw remains elusive. This work investigates bagasse and straw supply, conditioning, and pretreatment in a pilot-scale steam-explosion continuous reactor (~ 10 kg/h feed) to illuminate the critical feedstock differences for process scale-up. Evaluating biomass across four sequential harvest seasons (2018–2021) shows that straw supplied in bales requires extra conditioning to reduce mineral matter and particle size before feeding into the reactor. Moreover, straw composition is more variable and consistently has lower contents of glucan (35.6–38.8%) and carbohydrate potential (glucose + xylose, 649–704 kg/dry tonne) compared to bagasse (40.8–42.9%; 735–760 kg/dry tonne). Biomass pretreatments without (190 °C, 5–15 min) and with sulfuric acid catalyst (149–170 °C; 5–15 min; 0.5–5.12%, m/m) show that straw differs from bagasse by presenting a higher acid neutralization capacity and about 5% of labile glucans. These results suggest that straw crushing and aqueous pre-extraction are promising strategies to reduce the dissimilarities with bagasse, thus facilitating the development of feedstock-agnostic biorefining. [ABSTRACT FROM AUTHOR]

This article presents a new method for synthesizing quinoxalines, a versatile class of compounds with applications in medicine, agriculture, and materials science. The authors demonstrate that their method, which uses meglumine sulfate as a catalyst, is simple, efficient, and produces high-quality products. The article includes experimental details and characterization data for the synthesized compounds, which include various quinoxaline derivatives. The document also includes acknowledgments and a disclosure statement. [Extracted from the article]

Hydrodeoxygenation (HDO) is a promising way to produce the second generation biodiesel from aliphatic acid based biomass. In this study, NixMoy@NC bimetallic catalysts with varying molar ratios were prepared using ZIF-8 as a representative MOF precursor. Lauric acid was chosen as the model compound, the catalytic performance of these catalysts with different metal ratios, reaction temperatures, and pressures was investigated. In addition, the reaction of lauric acid, lauric alcohol, and lauric aldehyde at different reaction times were investigated to explore the pathways of lauric acid. The influence of Mo doping on the catalyst structure, reducibility, and electronic properties was investigated through a series of characterizations, including SEM, TEM, XPS, H2-TPR, and NH3-TPD. This study revealed that the ZIF-8 support with incorporated Ni and Mo maintained a stable structure. Compared to Ni-based catalysts, the addition of Mo in the bimetallic catalyst can bring the electron transfer between Ni and Mo and increased the active sites and acid sites. An appropriate amount of Mo can lower the reduction temperature and enhance the catalytic activity for hydrogenation and deoxygenation reactions. Based on the catalytic experimental results, it can be observed that liquid alkanes, such as undecane and dodecane, are primarily formed through decarbonylation of lauric aldehyde and hydrodeoxygenation of lauric alcohol. Additionally, under high-temperature conditions, the hydrodeoxygenation reaction is favored over the decarbonylation reaction, promoting the production of dodecane. This indicates that Mo exhibits better activation for the C–OH reaction, leading to these observations. Under repeated use, the catalyst still has good catalytic activity and stability. [ABSTRACT FROM AUTHOR]

Detailed quantum‐chemical calculations have been carried out to understand both the origin of the catalysis in the urea‐catalyzed nucleophilic ring‐opening of nitrocyclopropanes and the acceleration induced by the presence of an internal Lewis acid in the catalyst. To this end, the mode of activation of these ureas is quantitatively analyzed in detail by means of the Activation Strain Model of reactivity in combination with the Energy Decomposition Analysis method. It is found that the presence of the Lewis acid in the urea further enhances the interaction between the reactants, by increasing both the electrostatic and orbital attractions, which translates into a reduced activation barrier. This insight is also used to assess the impact of the nature of the Lewis acid on the transformation, facilitating the rational design of more active catalysts. [ABSTRACT FROM AUTHOR]

Edible oils are one of the renewable sources that enable the possibility of producing biodiesel sustainably. The transesterification of canola oil with methanol using cesium-modified phosphotungstic acid (Cs2.5H0.5PW12O40) as a heterogeneous catalyst was studied. Reaction conditions, specifically reaction time, catalyst loading, and the ratio of methanol to canola oil, were systematically explored. The canola oil conversion reached 55% at room temperature after 24 h. The reusability tests showed that the conversion of canola oil to biodiesel was maintained. [ABSTRACT FROM AUTHOR]

Increasing the efficiency of cellulose hydrolysis is a crucial milestone to enable its use as a platform for the production of renewable chemicals. Consequently, exploring alternative techniques for cellulose dissolution and subsequent depolymerization and hydrolysis remains a pivotal area of research. This study delves into the performance of diverse solid acid catalysts (ion-exchange resins, metal oxides, and zeolites) for cellulose depolymerization when combined with a concentrated solution of zinc chloride (ZnCl2) as the reaction medium and extractant. The influence of this molten salt hydrate on cellulose dissolution and the stability of the tested catalysts was thoroughly investigated. Optimal mild operating conditions (90 °C and 2 h) that facilitate enhanced conversion and selective glucose production were identified. The highest glucose yields (exceeding 40%) were obtained with Amberlyst-15 and HZSM-5 (SiO2/Al2O3 = 23), effectively mitigating product degradation and equaling or surpassing the traditional homogeneous system using H2SO4. Furthermore, insights into the deactivation mechanisms affecting the best catalysts are provided. [ABSTRACT FROM AUTHOR]

In the present work, the use of enzymatic hydrolysis to obtain cellulose nanofibers composed of purified cellulose from sugarcane bagasse (SCB) and oil palm empty fruit bunches (OPEFBs) was addressed. First, the cellulose was purified by applying hydrothermal treatments conducted at various temperatures (180 and 200 °C) and times (10, 20 and 30 min) and then 2% (m/v) sodium chlorite treatment. Then, enzymatic hydrolysis was conducted for 24, 48 or 72 h using cellulase from Trichoderma reesei at 50 °C and pH = 5.0 to isolate the cellulose nanofibers. The composition, morphology, crystallinity, thermal stability and zeta potential characteristics were evaluated for each cellulosic material. The crystallinity index increased significantly after hydrothermal pretreatment and bleaching from 42.6% to 87.3% and from 42.5% to 86.1% for SCB and OPEFB, respectively. In addition, the obtained pulps showed better thermal stability than residues when used as feedstock. Enzymatic hydrolysis was effective at extracting cellulose nanofibers, as long as the reaction time was controlled to less than 48 h, to avoid compromising the crystallinity and thermal stability of the isolated nanostructures. The enzymatic pathway is a promising alternative to the use of acid catalysts. [ABSTRACT FROM AUTHOR]

Carbon xerogel was prepared by a sol–gel technique by mixing formaldehyde with dissolved resorcinol in acetone solution using picric acid as a catalyst, followed by pyrolysis treatment at the desired temperature. X-ray diffraction analysis revealed that the obtained product has an amorphous phase, with an average grain size of approximately 2 nm. Scanning electron microscopy showed the existence of a mesoporous structure in the resorcinol–formaldehyde (RF) matrix with a pore size of about 50 nm. The electrical measurements carried out on our material showed interesting results. In fact, DC conductivity indicated that the xerogel is transformed from an insulating phase to a carbon-conducting phase under the pyrolysis temperature effect. The current–voltage (I–V) characteristics of the sample prepared at 650°C show different regions—an ohmic region at low applied voltages and a negative differential resistance (NDR) region at higher voltages, with the NDR phase appearing above a threshold voltage. Also, a hysteresis effect depending on the synthesis and measurement parameters was observed. The observed behaviors are explained in terms of the filament formation phenomenon and the Joule heating effect. These interesting behaviors are promising for threshold switching and neuromorphic computing applications. [ABSTRACT FROM AUTHOR]

Commercialised biodiesel, comprising of methyl esters, have large amounts of oxygenated compounds which cause low calorific value, high viscosity, poor low temperature performance and can only used in blends with petroleum-based diesel. Deoxygenation of these compounds can occur through three reaction pathways which are decarboxylation, decarbonylation, hydrodeoxygenation. The removal of oxygen can improve their fuel properties, and is heavily influenced by the presence of hydrogen (H2). However, given safety issues during transportation and storage of H2, the use of solvents to produce in-situ H2 for the deoxygenation process has been suggested as an alternative. The present work attempts to investigate the addition of solvents (deionised water, methanol, ethanol, 1-propanol, 2-propanol, n-hexane and cyclohexane) on the deoxygenation of methyl oleate to enhance its fuel properties. The experiments were carried out with unreduced bimetallic NiCo impregnated onto TiO2. Incorporation of NiCo onto TiO2 maintained the mesoporous nature of the support while increasing the number of strong acid sites of the catalyst, which can promote C-O bond cleavage during deoxygenation. Under hydrogen-restricted conditions, the deoxygenation is expected to occur mainly through decarboxylation and decarbonylation to produce alkanes and alkenes, with cracking to produce shorter chain methyl esters. The deoxygenation was conducted with 50 g methyl oleate, 40 g solvent, 5 wt% catalyst at 300 °C for 2 h in a pressurised nitrogen atmosphere. GCMS analysis show that the addition of 2-propanol showed the highest methyl oleate conversion (69.08 %) over other solvents, with 12.74 % selectivity for alkane formation. These results indicate the potential of solvent-aided deoxygenation of methyl esters for biofuel use. [ABSTRACT FROM AUTHOR]

The remediation of polluted water is a major concern for public health and the environment. Catalytic removal of model organic and inorganic pollutants in water using carbon catalysts has shown promising results. In the present work, stereolithographically 3D‐printed bio‐based carbon monoliths with different textural and surface chemistry properties were used as catalysts for oxalic acid oxidation and catalyst supports for bromate reduction in continuous systems. A significant synergistic effect between ozone or dihydrogen and carbon catalyst was evidenced by mineralization of 14–25 % of oxalic acid or reduction of 15–45 % of bromates in the steady state, respectively. The best results were achieved with samples with the highest mesoporous surface area or, in the case of lower surface area, with samples having the strongest basic character. As materials with great potential, optimizing the textural properties of architected carbon monoliths will enable them to compete with other macro‐structured carbon catalysts. [ABSTRACT FROM AUTHOR]

In this research, a suitable and efficient CoFe2O4@ZnO@Bentonite nano-catalyst was designed and synthesized by using zinc oxide (ZnO) and cobalt ferrite (CoFe2O4) nanoparticles and bentonite by microwave irradiation. Characteristics of the synthesized nanocomposite were investigated by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), transmission electron microscope (TEM), X-ray diffraction (XRD), Bruner-Emmett-Teller (BET) and vibrating sample magnetometer (VSM) techniques. The produced catalyst was effectively employed as a supported solid acid catalyst in mildly agitated three-component reactions involving aromatic aldehydes, 4-hydroxycoumarin, and 1,3-dimethyl-barbituric acid in a single pot to produce benzylbarbiturocoumarins. Starting materials were condensed via three C-C bond formation by CoFe2O4@ ZnO@Bentonite as an efficient, recyclable, and environmentally safe nanocatalyst to obtain target products. The advantages of this method include using a natural substrate, small amounts of catalyst, aqueous media, performing reactions at ambient temperature, simple separation and purification of products, and good yields with short reaction times. [ABSTRACT FROM AUTHOR]

The chemical space of chiral Brønsted acid catalysts is defined by quantity and complexity, reflecting the diverse synthetic challenges confronted and the innovative molecular designs introduced. Here, we detail how this successful outcome is a powerful demonstration of the benefits of utilizing both local structure searches and a comprehensive understanding of catalyst performance for effective and efficient exploration of Brønsted acid properties. In this concept article we provide an evolutionary overview of this field by summarizing the approaches to catalyst optimization, the resulting structures, and functions. [ABSTRACT FROM AUTHOR]

Designing low-cost and efficient catalysts for formic acid dehydrogenation (FAD) is crucial to facilitate the practical applications of formic acid as a hydrogen carrier. Using density functional theory calculations, we designed nine graphdiyne-supported Pd/Cu single-, double-, and triple-atom catalysts, investigating their stability and formic acid dehydrogenation performance. The results indicate that as the number of active metal sites increases, the catalytic activity for formic acid dehydrogenation improves, i.e., M 3 @GDY > M 2 @GDY > M 1 @GDY (M = Pd/Cu). Moreover, a synergistic effect between Pd and Cu atoms is observed in Pd x Cu 3-x @GDY, where the activity sequence of triple-atom catalysts was Pd 1 Cu 2 @GDY > Pd 2 Cu 1 @GDY > Pd 3 @GDY > Cu 3 @GDY. Particularly, Pd 1 Cu 2 @GDY exhibits superior FAD catalytic activity and hydrogen selectivity, presenting a potential novel formic acid dehydrogenation catalyst. Electronic structure analysis indicates that the band center difference Δε (Δε = ε d - ε p) serves as an assessment descriptor for formic acid dehydrogenation activity. Microkinetic analysis further confirms the performance of TACs predicted by DFT results, and shows that all TACs have good H 2 selectivity even at a high temperature. [Display omitted] • A series of Pd x Cu y @GDY catalysts for formic acid dehydrogenation were designed. • Pd 1 Cu 2 @GDY shows best activity and H 2 selectivity among all catalysts. • Band center difference is a good descriptor of the catalytic activity. [ABSTRACT FROM AUTHOR]

Density functional theory and a semi-empirical quantum chemical approach were used to evaluate the photocatalytic efficiency of ceria (CeO2) combined with reduced graphene oxide (rGO) and graphene (GP) for degrading methylene blue (MB). Two main aspects were examined: the adsorption ability of rGO and GP for MB, and the separation of photogenerated electrons and holes in CeO2/rGO and CeO2/GP. Our results, based on calculations of the adsorption energy, population analysis, bond strength index, and reduced density gradient, show favorable energetics for MB adsorption on both rGO and GP surfaces. The process is driven by weak, non-covalent interactions, with rGO showing better MB adsorption. A detailed analysis involving parameters like fractional occupation density, the centroid distance between molecular orbitals, and the Lewis acid index of the catalysts highlights the effective charge separation in CeO2/rGO compared to CeO2/GP. These findings are crucial for understanding photocatalytic degradation mechanisms of organic dyes and developing efficient photocatalysts. [ABSTRACT FROM AUTHOR]

The aqueous-phase hydrogenolysis of glycerol was studied in Ni/CeO2 catalytic systems prepared by incipient wetness impregnation. The operating conditions were 34 bar, 227 ºC, 5 wt.% of glycerol, and a W/mglycerol = 20 g catalyst min/g glycerol without a hydrogen supply. The effect of the catalyst preparation conditions on the catalytic activity and physicochemical properties of the catalysts was assessed, particularly the calcination temperature of the support, the calcination temperature of the catalyst, and the Ni content. The physicochemical properties of the catalysts were determined by N2 adsorption, H2-TPR, NH3-TPD, and XRD, among other techniques. A relevant increase in acidity was observed when increasing the nickel content up to 20 wt.%. The increase in the calcination temperatures of the supports and catalysts showed a detrimental effect on the specific surface area and acid properties of the catalysts, which were crucial to the selectivity of the reaction. These catalysts notably enhanced the yield of liquid products, achieving global glycerol conversion values ranging from 17.1 to 29.0% and carbon yield to liquids ranging from 12.6 to 24.0%. Acetol and 1,2-propanediol were the most abundant products obtained in the liquid stream. [ABSTRACT FROM AUTHOR]

Developing highly effective iron-based catalyst to selectively remove organic contaminants has garnered considerable attention. Herein, a magnetic Fe0/FeS2-doped carbon nanolayer (S-Fe@NC) was synthesized through a straightforward one-step pyrolysis method, pyrolyzing a mixture composed of 4,6-dihydroxypyrimidine, trithiocyanuric acid, and FeCl3·6H2O. With the presence of PMS, S-Fe@NC demonstrated the ability to remove almost 100% bisphenol-A (50 μM) within 3 min, attributed to its excellent graphitization degree and high FeS2/Fe0 content. Furthermore, the S-Fe@NC catalyst demonstrated an impressive kobs value of 1.476 min−1, which surpassed the traditional Fenton system by 77 times and even exceeded the commercial Fe0 catalyst by 127 times. More importantly, the S-Fe@NC/PMS system succeeded in selectively removing organic contaminants based on the hydrophobic interaction between catalyst and contaminants. Besides, the result of electron paramagnetic resonance and the radical quenching experiments indicated that ·OH, SO4·−, 1O2, and O2·− were involved in the organic contaminants removal. Interestingly, after adding ascorbic acid (AA) to the S-Fe@NC/PMS system, more ROS could be generated to result in the kobs augmenting by 4.16 times (6.133 min−1), completely different from the common sense that AA was usually used as a radical quencher. Additionally, the magnetically separable catalyst also exhibited excellent reusability and broad pH adaptability (2.0–12.0). This study provided a valuable insight for developing highly selective and effective Fe-based catalyst for practical wastewater treatment. [ABSTRACT FROM AUTHOR]

In this work, highly efficient carbon‐supported Pd‐based catalysts for formic acid dehydrogenation were synthesized by a straightforward wet impregnation‐reduction method. The carbon support was obtained from a biomass residue (almond shell) prepared via H3PO4‐assisted hydrothermal carbonization (HTC) and thermal activation. This carbon support was doped with nitrogen groups to study the effect on the electronic properties and catalytic performance of the catalysts. Investigating the formation of PdAg alloys with varying Pd : Ag molar ratios resulted in catalysts exhibiting enhanced catalytic activity compared to monometallic Pd counterparts. Notably, the Pd1Ag0.5/NAS catalyst displayed outstanding catalytic performance, achieving an initial TOF of 1716 h−1 (calculated in the first 3 minutes of reaction and expressed per mole of Pd) and maintaining substantial activity over 6 consecutive reaction cycles. This work elucidates the successful synthesis of effective catalysts, emphasizing the influence of nitrogen doping and PdAg alloy composition on catalytic behavior and stability. [ABSTRACT FROM AUTHOR]

Fluorinated arylborane‐based Lewis acid catalysts have shown remarkable activity and serve as ideal examples of transition metal‐free catalysts for diverse organic transformations. However, their homogeneous nature poses challenges in terms of recyclability and separation from reaction mixtures. This work presents an efficient technique for the heterogenization of boron Lewis acid catalysts by anchoring Piers' borane to allyl‐functionalized iron oxide. This catalyst demonstrates excellent activity in the hydrosilylation of imines and the reductive amination of carbonyls using various silanes as reducing agents under mild reaction conditions. The catalyst exhibits broad tolerance towards a wide range of functional substrates. Furthermore, it exhibits good recyclability and can be easily separated from the products using an external magnetic field. This work represents a significant advance in the development of sustainable heterogenous metal‐free catalysts for organic transformations. [ABSTRACT FROM AUTHOR]

For the controllable transformation of C3–6 diols in ethylene glycol (EG), a H-Beta zeolite catalyst was modified with NH3via incomplete desorption. 60.8% of acid sites on the zeolite were deactivated, but the ratio of strong acid sites was obviously increased. With 1,2-pentanediol (PDO) as a representative large-carbon-number diol, the undesirable acetalization and oligomerization reactions of EG were suppressed in the EG-PDO reaction system over the modified catalyst due to their dependency on total acid sites. NH3-TPD and FTIR results proved that Lewis acid sites on the modified zeolite were eliminated after modification, resulting in the suppression of acetalization and oligomerization reactions. In contrast, a portion of strong Brønsted acid sites still remained, ensuring the catalytic transformation of PDO. Only 8.2% of EG was consumed after 8 h reaction, and the conversion of PDO could reach 84.3%. The loading of NH3 on the surface of zeolite pores led to diffusion resistance, slightly decreasing the reaction rate of PDO without affecting the reaction selectivity. The catalytic reactions of other C3–6 diols in EG followed similar principles, and the selectivity to aldehydes or ketone was improved over this modified catalyst. Non-diol biomass hydrogenation products such as glycerol had a negative influence on the selectivity, so these components should be isolated before the reactions. This catalyst could be reused at least 5 times, and the conversion of PDO slightly decreased. This work sheds light on the relationships between the acid properties of the catalyst and different reactions of diols. [ABSTRACT FROM AUTHOR]

Herein, we report thiouracil‐catalyzed α‐selective O‐glycosylations employing easily accessible glycosyl trichloroacetimidate donors without using any co‐catalyst or additive. A variety of alcohol nucleophiles including saccharides, and amino acids with different protecting groups containing glycosyl trichloroacetimidate donors were successfully α‐glycosylated using an operationally simple protocol. Moreover, mechanistic investigations suggest that thiouracil functions as Brønsted acid/base catalyst in this glycosylation process. [ABSTRACT FROM AUTHOR]

The atroposelective transformation of alkynes is an efficient protocol for the assembly of axially chiral compounds. Benefitting from the rapid development of chiral organocatalysts, the organocatalytic atroposelective reactions of alkynes have been extensively studied over the past decades. An array of chiral catalysts, including chiral Brønsted acid catalysts, secondary amine catalysts, N -heterocyclic carbene (NHC) catalysts, thiourea catalysts and N -squaramide catalysts, are employed in enantioselective reactions of different alkynes. This short review summarizes the recent advances on organocatalytic atroposelective reactions of alkynes according to the type of alkyne substrate. The reaction mechanisms, modes of enantiocontrol, product diversity and applications are highlighted. 1 Introduction 2 Electron-Rich Aryl Alkynes 3 Electron-Deficient Aryl Alkynes 4 Other Types of Alkynes 5 Conclusion and Outlook [ABSTRACT FROM AUTHOR]

Zirconium ions incorporated into the secondary structure of the Keggin type heteropoly tungstate by titration method by varying the zirconium content. The FT-IR, Laser Raman, and XRD analysis of the synthesized catalysts revealed that the incorporation of the zirconium does not affect the primary structure of the Keggin ion. The quantitative acid measurement of the catalysts was done by TPD-NH3 technique. The type of acid site was identified by adsorbing pyridine on the catalyst and qualitative analysis was carried out by DRIFTS. The activity of the catalysts was tested for the glycerol carbonylation using urea as a CO source. The catalyst with moderate content of Zr4+ ions in the secondary structure presented high activity. Catalysts acidity and activity depend on the intact primary Keggin heteropoly tungstate together with the counter ions type and its size in the secondary structure and catalyst calcination temperature. [ABSTRACT FROM AUTHOR]

Sulfonated carbon catalysts exhibit superior catalytic performance for production of biobased chemicals, but the catalyst preparation approaches are still suffered from high corrosion and possible pollution risks. In this paper, lignin extracted from corn stover was used to prepare lignin-based activated carbon, which was then subjected to grafting modification by sulfur dioxide nonthermal plasma method to construct a novel lignin-derived solid acid catalyst (LP-LDSA). The catalytic performances of LP-LDSA were further determined by dehydration of fructose to produce 5-HMF in a biphasic solvent system composed by dimethyl sulfoxide (DMSO) and water. Under the optimal conditions, the 5-HMF yield and reaction selectivity were 88.9% and 89.4%, respectively. This LP-LDSA catalyst also exhibited excellent stability and reusability in five sequential reaction batches. This method has advantages of shorter solid acid preparation duration, lower energy consumption, and higher catalytic stability, presenting an innovative and green method for sulfonation production of solid acid catalyst. [ABSTRACT FROM AUTHOR]

K-doped MoVTeNbOx were prepared rapidly and simply by spray drying method and applied to catalyze the selective oxidation of propane to acrylic acid. Results show that doping of K could affect the relative content of M1 and M2 phases in MoVTeNbOx. The as-prepared K-doped MoVTeNbOx exhibited a unique spherical structure agglomerated by needle particles. These needles shaped particles interlaced and stacked with each other to form a mesoporous structure with an average pore size range of 27.26 to 50.78 nm. Moreover, compared with undoped catalysts, doping of K increased the surface V5+ active sites content of the MoVTeNbOx from 60 to 75%. For the conversion of propane to acrylic acid, an appropriate amount of M2 increased the conversion of propane. The selectivity of K-doped MoVTeNbOx catalyst for acrylic acid was significantly improved, possibly due to the distinct reduction in the number of medium acid sites caused by the introduction of K. Furthermore, the special mesoporous structure formed boosted the adsorption and activation of the catalyst for propane and the diffusion of product, which is important to improve the catalytic performance of MoVTeNbOx. Under the optimal reaction condition, the maximum selectivity and yield of K-doped catalyst (K/Mo = 0.005) for acrylic acid reached 72.06% and 49.57%, respectively. Mesoporous K-doped MoVTeNbOx catalyze the direct oxidation of propane to acrylic acid [ABSTRACT FROM AUTHOR]

Synthesis method effect on surface properties of doped V2O5 metal oxide into CaO-based catalysts as acid–base bifunctional catalysts have been studied. Various acid–base bifunctional catalysts were synthesized via co-precipitation, impregnation, and physical mixing methods. X-ray diffraction (XRD), Fourier Transform Infra-Red (FT-IR) and X-ray fluorescence (XRF) analyses of all prepared samples confirmed that V2O5 was well dispersed on the surface of CaO catalysts. V2O5-CaO catalyst synthesized via the co-precipitation method exhibited the highest FAME yield (78.48%) under mild reaction conditions with waste cooking oil among other synthesized catalysts. This superiority is attributed to its highest total acid–base sites per catalyst surface area and mesoporous structure. The simultaneous esterification-transesterification activity was greatly affected by catalyst surface properties (i.e., the strength of acidity and basicity), the total amount of acid–base sites, and surface area. These results were supported by the N2-adsorption, Temperature Programmed Desorption (TPD)-CO2, and TPD-NH3 data. Thus, our work showed that co-precipitation was the most promising preparation method for maximizing the total acid–base sites per catalyst surface area and acid–base strength of the catalyst. The remarkable strength of the acid–base and total amount of acid–base sites of the V2O5-CaO catalyst is caused by the synergistic effect of the dual acid sites (Brønsted and Lewis) and base sites on the catalysts. [ABSTRACT FROM AUTHOR]

A porous Sn–Er–Beta zeolite catalyst was rapidly prepared by introducing Sn source with water bath method and Er source with solid-state ion exchange method. When adding 180 mg catalyst, 225 mg glucose and 10 mL water into a reaction kettle at 200 °C for 2 h, the yield of lactic acid can reach 71.2%. After being recycled 5 times, the lactic acid yield of the catalyst can still reach 45.3%. The physical and chemical properties of Sn–Er–Beta zeolite were characterized, and it was confirmed that the catalyst had a multi-stage pore structure, with Sn and Er elements existing in the zeolite skeleton. Among them, the increase of Lewis acidity, Brønsted acidity and special strong alkaline sites of Sn–Er–Beta zeolite caused by the introduction of Sn, and the Lewis acidic sites are further increased after the introduction of Er. The combination of Sn and Er obviously improves the catalyst's capability to catalyze glucose and fructose to produce lactic acid. This provides an important reference value for the directional catalytic process of sugars. [ABSTRACT FROM AUTHOR]

Polymer supported ferric chloride catalyst is prepared and characterized by IR, SEM, TEM, EDS, TGA, ICP-MS and XRD. The heterogenized Lewis acid catalyst was found to efficiently promote three component Biginelli reaction, where the 3,4-dihydropyrimidine-2(1H)-ones/thiones were efficiently synthesized from urea/thiourea. The catalyst was found to be quite robust for this reaction with very less leaching of metal was observed, and hence can be efficiently recycled. The catalyst was found to be effective for multiple uses, establishing its reusability in this important reaction. [ABSTRACT FROM AUTHOR]

Both the alkyl sulfonic acid and phenyl sulfonic acid groups were incorporated onto a hypercrosslinked porous polymer through copolymerization and post-sulfonation to form novel PDVB-SO3H-SO3H catalyst. The porous polymer based solid acid. PDVB-SO3H-SO3H was applied to the cayaltic synthesis of thioacetal (thioketal) at room temperature. N2 adsorption isotherm experiments demonstrated that the catalyst possessed the significantly high BET surface area. In comparison with conventional homogeneous acid catalysts such as sulfuric acid and p-toluenesulfonic acid, the porous polymer based solid acid. PDVB-SO3H-SO3H showed several noteworthy advantages, including remarkable catalytic activity at room temperature and mild reaction conditions, broad substrates scope, high specific surface area, exceptional acid strength, flexible hydrophobicity, and excellent recyclability. These exceptional features make the polymer a highly promising candidate for diverse industrial applications. [ABSTRACT FROM AUTHOR]

The synthesis of biodiesel can be achieved using either homogeneous or heterogeneous catalysts. Given the non-renewable nature of homogeneous catalysts, heterogeneous catalysts are increasingly preferred for biodiesel production. Agricultural wastes serve as a viable source for these heterogeneous catalysts, contributing to environmental sustainability. This study introduces a novel, eco-friendly, cost-effective, and efficient heterogeneous catalyst that was developed and derived from Citrus limetta peels for biodiesel production. The catalyst was thoroughly characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffractograms (XRD), Field Emission Scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX). Coconut oil, a rich and renewable resource, was used as the feedstock for the biodiesel synthesis. The conversion process was confirmed by 1H NMR, IR spectra, mass spectra, and 13C NMR of the biodiesel. The developed method using the Citrus limetta peel-derived catalyst demonstrated a 100% yield. The results show the optimum conditions for biodiesel synthesis are 1 w/v (for the catalytical dose), with a 6:1 methanol/oil ratio at 60 °C for 3 h. The synthesized biodiesel exhibited a high cetane value of 54, contributing to improved ignition and reduced engine noise. Its sulfur-free composition, boiling point of 294 °C, high viscosity of 2.5 mm2/s, acid value of 0.09 mgKOH/g, and flash point of 142 °C enhance its environmental profile. The catalyst can be used for up to five cycles, underscoring its potential as a cost-effective and sustainable approach for biodiesel production. [ABSTRACT FROM AUTHOR]

Four novel Pd (II), Cu (II), VO (II), and Ag(I) complexes were prepared from benzimidazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, DFT/time‐dependent DFT computations were performed applying (B3LYP/6‐311++G[d,p]/aug‐cc‐pVTZ/aug‐cc‐pVTZ‐PP) level in order to investigate the electronic behavior of the compounds. These results demonstrated good agreement with the experimental data. Computational data discriminate Pd (II) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives using microwave irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for 3‐methyl‐5‐pyrazolone, aromatic aldehyde, and 5‐aminotetrazole was carried out under mild reaction conditions by microwave irradiation. All reaction conditions were optimized among those variable Lewis acid catalysts in comparison with our new complexes. DOBPAPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds over z‐axis and supported by theoretical aspects. [ABSTRACT FROM AUTHOR]

As an important class of nitrogen-containing fused heterocyclic compounds, imidazo[1,2-a]pyridines often exhibit significant biological activities, such as analgesic, anticancer, antiosteoporosis, anxiolytic, etc. Using Y(OTf)3 as a Lewis acid catalyst, a simple and efficient method has been developed for the synthesis of C3-alkylated imidazo[1,2-a]pyridines through the three-component aza-Friedel–Crafts reaction of imidazo[1,2-a]pyridines, aldehydes, and amines in the normal air atmosphere without the protection of inert gas and special requirements for anhydrous and anaerobic conditions. A series of imidazo[1,2-a]pyridine derivatives were obtained with moderate to good yields, and their structures were confirmed by 1H NMR, 13C NMR, and HRMS. Furthermore, this conversion has the advantages of simple operation, excellent functional group tolerance, high atomic economy, broad substrate scope, and can achieve gram-level reactions. Notably, this methodology may be conveniently applied to the further design and rapid synthesis of potential biologically active imidazo[1,2-a]pyridines with multifunctional groups. [ABSTRACT FROM AUTHOR]

The development of cost-effective and highly efficient biochar-based catalysts is essential for the catalytic steam reforming process of bio-oil. In this study, pickling peanut shell biochar was used to prepare biochar-supported Ni/Co monometallic catalyst and biochar-supported nickel-Co bimetallic catalyst through the impregnation method. The catalytic effect of these catalysts on acetic acid (a bio-oil model compound) steam reforming was investigated. It was found that Co could enhance the dispersion of metal particles. The catalyst exhibited the best catalytic effect and significantly improved resistance to carbon deposition with a loading of 8 wt% and a Ni-to-Co ratio of 6:2. At the temperature of 600 °C and the S/C ratio of 3, the selectivity of H2 reached 84.48 %, and the conversion of acetic acid reached 95.49 %. A synergistic effect was observed between Ni and Co, leading to increased metal dispersion, enhanced reducibility, and a higher number of active centers. Co facilitates water dissociation and promotes the oxidation of C–H and mobile O, resulting in a faster decarbonization rate. The effective utilization of biochar-based catalysts and the rational utilization of bio-oil contribute to the timely achievement of carbon emission reduction targets. [ABSTRACT FROM AUTHOR]

We have developed a one-pot, four-component synthetic approach utilizing 5-sulfosalicylic acid dihydrate (5-SSA.2H2O) as an organocatalyst, enabling the synthesis of polyfunctional 3-pyrrolin-2-one molecules by employing dialkylacetylenedicarboxylate, amines, and either formaldehyde or aromatic aldehydes at room temperature. This approach presents numerous notable benefits such as shorter reaction time, simple and eco-friendly procedure, excellent yield, broad applicability across various substrates, and the use of a cost-effective, easily accessible and biodegradable catalyst. The structures of the 3-pyrrolin-2-one molecules were confirmed using techniques such as FTIR, 1HNMR, 13CNMR and HRMS. Overall, this study demonstrates a promising method for producing environmentally friendly polyfunctional 3-pyrrolin-2-one efficiently and smoothly at ambient temperature. [ABSTRACT FROM AUTHOR]

To better apply solid acid catalysts for hydraulic cavitation technology, a ZrO2-ZSM-5 solid acid catalyst was prepared using impregnation and ion-exchange methods. The effects of the catalyst, hydrogen peroxide, and formic acid dosages, reaction temperature, and venturi tube type on the epoxidation of soybean oil were investigated. The appropriate reaction conditions were determined through a series of experiments: n(C = C):n(HCOOH) = 1:3.0, n(C = C):n(H2O2) = 1:2.2, reaction temperature 70 °C, catalyst dosage 1 wt%, and the reaction time 3 h. The epoxy value of the optimized product reached 6.19%. After the reaction, the catalyst was recovered, and catalyst-related mechanisms were hypothesized in conjunction with related analyses. A catalytic mechanism is proposed, and an explanation is provided on how the catalyst accelerates the reaction process. It was concluded that the catalyst can be effectively applied to the epoxidation reaction under the action of hydraulic cavitation, and the reaction rate can be effectively improved. [ABSTRACT FROM AUTHOR]