Here in, we have fabricated a composite of SiC and g-C 3 N 5 to form a noble -metal -free heterostructure as SiC/gC 3 N 5 for electrochemical HER activity. More than a few characterization techniques were investigated for their structural properties, such as the XRD, UV- DRS, FT-IR, FE-SEM, HR-TEM, and XPS measurements respectively. The HER reaction of SiC/g-C 3 N 5 heterostructure with an overpotential obtained from Tafel slope of 81 mV/dec vs RHE at 10 mA/cm 2 which is much better than that of the pristine SiC material. This work entitles that the effective approach for the rational design of g-C 3 N 5 -based electrocatalysts, for future developments in metal -free electrocatalysts.
The 2D transition metal WSe2, a strong photocatalyst, was combined with BiVO4 to create a p-n heterojunction photocatalyst using a hydrothermal process. The resulting 10% WSe2/BiVO4 (in the synthesized material, the mass ratio of WSe2 to BiVO4 is 1:10) composite showed impressive 94.5% efficiency in Methylene Blue (MB) degradation under visible light. Even after eight cycles, it maintained a 72% degradation rate, demonstrating robust photocatalytic stability. Experiments, including ·O2− and h+ capture and ESR analysis, revealed their vital roles in photocatalytic degradation. The exceptional performance of WSe2/BiVO4 is attributed to the internal electric field formed between WSe2 and BiVO4, enhancing carrier mobility.
In this study, Fe2O3/C3N4/NH2-MIL-125 ternary composite photocatalysts were synthesized. Their amino groups provided close bonding between these materials, facilitating the effective separation of electrons and holes. Besides, each component of Fe2O3/C3N4/NH2-MIL-125 plays a crucial role. NH2-MIL-125 provided a high surface area, C3N4 contributed to the primary photocatalytic activity, and Fe2O3 aided in enhancing light absorption, generating additional potential to produce hydroxyl radicals, thereby further enhancing photocatalytic activity. Moreover, the proportion of loaded Fe2O3 and C3N4 in the ternary material was investigated. It was found that Fe2O3/C3N4/NH2-MIL-125 with a 1:1 ratio of Fe2O3 and C3N4 (FeCN1:1/NM125) exhibited excellent photocatalytic performance, in which RhB degradation reached 100% under visible light irradiation, conforming to first-order kinetics analysis with a reaction rate constant k of 0.0164 min−1. Its efficiency was twice that of the binary catalyst C3N4/NH2-MIL-125 or Fe2O3/NH2-MIL-125, seven times that of the pristine catalyst C3N4, and ten times that of the pristine catalyst NH2-MIL-125. Scavenger experiments showed that the degradation efficiencies were 52.57%, 55.51%, and 63.41%, respectively, indicating that three active species, namely superoxide radicals, holes, and hydroxyl radicals, made significant contributions to photocatalysis.
A novel Deep Eutectic Solvent (ChCl/THFTCA-DES) was prepared by a mixture (2:1) of choline chloride [(CH3)(3)N+ CH2CH2OH]Cl- = (ChCl) and tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA) as a cheap, simple, and non-toxic method, characterized by FT-IR, densito-meter, eutectic point, and H-1 NMR techniques and used as a capable and new catalyst for the synthesis of ten Henna-based benzopyranophenazine-carbonitriles.
Zeolite with nanoscale in some dimensions always display better catalytic performance because it contains more exposed catalytic active sites. Herein, a Cu2+ exchanged SSZ-39 zeolite with nanosheet morphology was chosen as a catalyst for the preparation of 2-vinyl heterocycle ethers through decarboxylative cross-coupling of cinnamic acids with ethers. The template reaction conditions were optimized, and the possible reaction mechanism was proposed. Then, a wide range of 2-vinyl heterocycle ethers were prepared. The recycling experiment demonstrated the good sustainability of the catalyst. The potential value of the catalytic product was demonstrated through the bifunctional addition and hydrogenation reduction.
5 wt% ruthenium-loaded Zeolite- beta is found to be efficient for hydrotreating the lignin model compound, m-cresol, at 170 degrees C under 10 bar hydrogen pressure to give methyl cyclohexane. The catalyst has a bifunctional nature in which the redox properties of ruthenium and the strong acidic nature of Zeolite- beta are instrumental in the hydrotreating of m -cresol. The well-dispersed metallic ruthenium on Zeolite- beta, as evident from TEM and EDS mapping analysis, is responsible for the potential activity. The activity was retained even after six cycles and was also found to have potential for hydrotreating various other functional substrates.
Reed flower-like SmMnOx and cauliflower-like SmMnOx-rGO catalysts were successfully synthesized by a coprecipitation-coupled solvothermal method for selective catalytic reduction (SCR) of NOx. The NOx conversion of the two catalysts is more than 90% in the temperature range of 75-200 degrees C, and the N2 selectivity of SmMnOxrGO is above 90%. Moreover, both of them exhibit more than 62% of resistance to H2O and SO2 at a very low temperature of 100 degrees C, much superior than the fluffy spherical SmMnOx prepared by coprecipitation method. The strong synergy between Mn and Sm endowed by the flower-like structure contributes to a low degree of crystallization, a high ratio of (Mn3++Mn4+)/Mn, more chemisorbed oxygen species, strong redox ability, and more Lewis acid sites, hence effectively enhancing low-temperature SCR activity and resistance to H2O and SO2. In addition, the decreased ratio of Mn4+/Mn after rGO doping hinders the side reaction of NH3 oxidation, thus enhancing the N2 selectivity of rGO-doped SmMnOx catalyst.
This study's objective is to examine the potential of the chitosan-supported Ag and Ag2O nanoparticles on the reduction of CO2. The transition state of the reduction reaction was systematically calculated using the nudged elastic band and the semi-empirical tight-binding calculations. It is found that the large charge polarization on the Ag and Ag2O nanoclusters can modulate chitosan's surface reactivity. The formation of the metal hydrates is the rate-determining step for reducing CO2. The calculated activation energy of the order of 1.5 eV demonstrates that Ag and Ag2O /chitosan could be used as catalysts for converting to CO2 formic acid.
It is critical to enhance the photocatalytic performance of BiOBr through appropriate strategies. Two BiOBr samples with different water (W) and ethylene glycol (EG) solvents have been synthesized. BiOBr-EG presents a 3D nest-like morphology composed of nanoplates, prominently emphasizing (110) facets. In contrast, BiOBr-W displays 2D microplates with exposed (102) facets. Notably, BiOBr-EG exhibits a degradation rate 7.4 times faster and removal efficiency of Enrofloxacin (ENR) 2.2 times greater than that of BiOBr-W. Additional investigations reveal that ·O2− plays a dominant role in the degradation process. Finally, the degradation pathways are explored through DFT calculation and HPLC-MS methods.
The increasing focus on sustainability has prompted researchers to investigate innovative catalytic methods for converting acids produced from biomass into value added ester compounds. The present study focuses on the efficient conversion of diverse biomass-derived acids into esters through the utilization of zeolite-based catalysts, capitalizing on their unique structural and acidic properties. The utilization of esters encompasses a wide range of applications, making them highly versatile as both platform chemicals and biofuels. Recent development and enhancement of catalytic systems based on zeolites are specifically reviewed for the efficient synthesis of ester compounds with significant commercial value from biomass derived acids.
Methane decomposition for hydrogen production is classified as blue turquoise, an intermediate between green and blue hydrogen. It does not generate greenhouse gas (GHG) emissions and does not require installation of carbon capture, utilization, and storage (CCUS) processes, becoming environmentally competitive among technologies, as the only byproduct is solid carbon. This research contributes to optimize temperature and gas hourly space velocity parameters for methane conversion adopting design of experiment (DoE) concept to collect data and identify significant factors through a 3(2) factorial design. Highest methane conversion, considering thermodynamic equilibrium limit of reaction, was obtained at 900 K and 6000 mL.h(-1).g(-1). The catalyst used was characterized by SEM, BET, and XRD.
Selective conversion of furfural can prepare various important chemicals, marking it as a prominent area of interest in biomass utilization. This paper reviews the latest progress in the direct conversion of furfural or its derivatives to 1, 5-pentanediol, 1, 2-pentanediol and 1, 4-pentanediol which are widely used high-value fine chemicals with great development potential in application. The recent catalytic methodologies employed in the synthesis of pentanediols from furfural and its derivatives, encompassing both noble metal and non-noble metal catalysts, have been comprehensively summarized. Furthermore, the challenges and opportunities in biomass-based pentanediols synthesis are analyzed, emphasizing catalyst importance and sustainable, eco-friendly production for pentanediols from renewable resources.
A novel bimetallic central covalent coupling catalytic system (Porp.Co@Zn-C6) based on Tris(4-Cl)(4-OH)Co and Tris(4-Cl)(4-OH)Zn was established to improve cycloalkanes oxidation. In particular, the partially-oxidized product's selectivity rose from 86.4% to 97.5% and the cyclohexane conversion was boosted from 3.80% to 4.41%. Simultaneously achieved improvements in conversion and selectivity. In this system, Co(II) was employed to activate molecular oxygen, Zn(II) was utilized to strengthen the utilization of cyclohexyl hydroperoxide and to be avoided its thermal decomposition in disorder state. This proposal can be very suitable for other cycloalkanes as well, which will improve the conversion and selectivity concurrently.
The impact of binder selection on catalytic performance of real catalyst extrudates is still limitedly shown in biomass catalysis. Herein, we have prepared two zeolite-based bifunctional extrudates (Ni/LaY-Al 2 O 3 and Ni/ LaY-SiO 2 ). Compared with Ni/LaY-Al 2 O 3 , Ni/LaY-SiO 2 shows a markedly enhanced durability and sustained performance for 936 h in the continuous liquid-phase hydrogenation of gamma -valerolactone into methyl pentanoate. Complementary characterization studies reveal that choosing SiO 2 as binder could efficiently mitigate metal agglomeration, coke formation and support dealumination during catalysis. These findings showcase that binder selection is essential for catalyst durability in the development of the industrial-level bifunctional catalysts for biomass valorization.
For the first time, the successful synthesis of 4,4-bis(5-methylthiophen-2-yl)pentanoic acid (bisthiophenic acid-methyl; BTA-M) and its alkyl esters (BTAE-M) from levulinic acid (LA) and its esters with 2-Methylthiophene (2-Met) has been achieved, utilizing solid acid catalysts (Amberlyst-15 and Indion-190). Notably, Indion-190, a cost-effective catalyst, demonstrated the formation of BTA-M and bisthiophenic methyl ester-methyl (BTME-M) with 96–98% selectivities and 99% conversion of LA and methyl levulinate under optimized, solvent-free reaction conditions. The recyclability of Indion-190 has been showcased, maintaining good recyclability for the preparation of BTA-M and BTME-M over three reaction cycles, with a slight decrease in the conversion of reactants.
A strategy to mitigate diffusion restrictions associated with heavy crude oil conversions is using mesostructured Y zeolite. In recent years, multiple routes have been proposed for obtaining materials with improved catalytic performance versus catalysts with higher molecular transport restrictions. Typically, after the implementation of these treatments, improvement in catalytic activity is correlated either with changes in textural properties (area and porous volume) or the modification of physicochemical properties (Si/Al ratio and acid strength); however, the correlation with diffusional mass transport characteristics is not typical. In this study, alkylaromatic molecules of different kinetic diameters, such as benzene, toluene, p-xylene, and m-xylene, were used as molecule probes to determine the effective diffusion through a pulse experiment under conditions of no adsorption or reaction. The studied solids include five commercial zeolites from the Zeolyst CBV series and four top-down mesostructured Y zeolites. The obtained concentration curves were fitted to an exponential decay model, a solution of the second Fick's law under defined experimental conditions, and correlation values between 0.9996 > R-2 > 0.9896 were found. Furthermore, the implementation of the descriptors "Transport ratio (TRMR)" and "Corrected transport ratio (TRMR (c))" was proposed, which allowed the combined representation of the change in the mass transport of aromatic probes and the changes in the acidity of the zeolite, after the application of top-down treatments. These descriptors proved simple and effective tools to correlate the changes after mesopore insertion with the catalytic performance in the 1,3,5-Triisopropylbenzene (TIPB) cracking reaction. Our approach is an integral method of screening mesostructured zeolites with an adequate balance of acidity and transport properties.
This study focuses on the synthesis of hierarchical nano-sized beta zeolites that exhibit enhanced catalytic properties through zeolite particle size reduction (to <80 nm) and the introduction of mesopores inside and between particles to improve diffusion of large molecules. The zeolites were produced by desilication and with template-including nano-sized beta as starting material. The samples were characterized by BET, XRD, XRF, solid-state NMR, TG-DTA, and NH3-TPD. Our method uses a shortened synthesis process to yield zeolites with higher surface area, pore volume (>1.0 ml/g), and stronger acidity that those developed by other methods. The zeolite reaction performances were evaluated in crude oil hydrocracking under commercial hydrocracker operating conditions in a pilot plant unit. The testing results showed that the catalyst including the hierarchical nanosized zeolite beta had much higher heavy oil conversion activity and naphtha selectivity.
Water pollution caused by antibiotics poses a serious threat to human health and ecosystems. Rapid and efficient removal of antibiotic pollution in water by photocatalysts is one of the effective means to protect the environment and public health. Herein, a wide-spectral responsive upconversion NaGdF4:Yb,Tm@Mn-MOFs core-shell nanostructures were built by coating hexagonal NaGdF4:Yb,Tm cores with amino-functionalized manganese carboxylate MOFs (Mn-MOFs) shells, which exhibited good water dispersibility. Mn-MOFs catalysts is mainly concentrated in the ultraviolet region, while NaGdF4:Yb,Tm nanoparticles can transform infrared light into visible light or even higher energy ultraviolet light, which is harvested by the Mn-MOFs. The optimized nanostructures were tested under simulated solar light (After 120 min irradiation) in the degradation of tetracycline, oxytetracycline hydrochloride and tetracycline hydrochloride, while their degradation rates reached 70%, 72% and 75%, respectively. The better photocatalytic mechanism for antibiotics than its individual components was elucidated, which provides a potential strategy to broaden the full spectrum absorption of the wide bandgap semiconductors and apply for the field of environmental remediation.
Several tertiary amine solutions with different structures were tested in the integrated CO2 capture and hydrogenation process in the presence of heterogeneous Pd/NAC catalysts. The tertiary amines of 3-dimethylamino-1,2-propanediol (3DMA-1,2-PD) and 3-diethylamino-1,2-propanedio (3DEA-1,2-PD) with high CO2 absorption capacity and high formate yield were selected as suitable candidates as CO2 capture and hydrogenation solvents. Under mild reaction conditions, a high formate yield of 68% was achieved when using 1 M 3DMA-1,2-PD solution with CO2 loading of 0.5 mol amine/mol CO2. In addition, the physico-chemical properties of the Pd/NAC catalysts were examined and the reaction mechanism of CO2 absorption and hydrogenation in the presence of Pd/NAC was proposed.
This review highlights Carbon Quantum Dots (CQDs) as promising photocatalysts for breaking down organic pollutants, particularly in advancing CQDs-based systems for degrading organic dyes. CQDs, used alone or combined with semiconductors, enhance performance. In scenarios with narrow bandgaps, CQDs assist in separating charges, whereas in wider bandgaps, they enable visible/NIR activity through up-conversion luminescence. When integrated into Z-scheme heterostructures, CQDs reduce recombination by facilitating electron transfer. Synthesis methods—both top-down and bottom-up—are explored along with crucial physicochemical properties. Furthermore, modifying CQDs through doping and integrating functional groups on their surface adjusts their characteristics, promising more effective CQDs-modified photocatalysts in future research.
