Catalytic Hydrolysis Research Articles

Cerium-based nanohydrolase for fast catalytic hydrolysis of β-lactam antibiotics in wastewater effluents

To defuse risks of antibiotic residues in effluent to achieve safe wastewater reuse, direct hydrolysis of the functional group responsible for the antibacterial activity, such as the of β-lactam ring in β-lactam antibiotics, has been recognized as an efficient and cost-effective strategy. However, the instability of natural hydrolases limits their use in treating antibiotic-containing wastewater. Herein, inspired by the active site of natural hydrolase, a Ce-based nanohydrolase was created for rapid hydrolysis of β-lactam antibiotics. The typical β-lactam antibiotic, penicillin G (PG), could be totally removed by the nanohydrolase within 2min with a hydrolysis efficiency of 44%, and the hydrolysis efficiency could reach 98% within 10min. It revealed that Ce(IV) in the nanohydrolase adsorbed PG via Lewis acid-Lewis base interaction to activate the β-lactam ring, while the -OH on Ce(III) served as nucleophile to attack the β-lactam ring, thereby promoting the hydrolysis of PG. The Ce-based nanohydrolase also showed good catalytic hydrolysis performance towards other commonly used β-lactam antibiotics and structurally related chemicals, implying its substrate universality. In addition to having high hydrolytic activity similar to that of natural hydrolases, this nanohydrolase exhibited extraordinary reusability and potential for practical applications that natural hydrolases do not possess. This work offers an innovative strategy to eliminate the risks of hydrolysable micropollutants in wastewater effluents and also provides reference for designing better nanohydrolase.

Preparation of two new chiral metal-organic frameworks for lipase immobilization and their use as biocatalysis in the enantioselective hydrolysis of racemic naproxen methyl ester

Considering the selective pharmacological activity of chiral drugs, it is important to develop new chiral materials to synthesize them. In this work, two new chiral MOFs (UiO-66@Np and UiO-66@Ib) were prepared by the covalent attachment of the chiral compounds (S-naproxen and S-ibuprofen) to the amine-functionalized Zr-MOF (UiO-66-NH2). Then, Candida rugosa lipase (CRL) was immobilized on these chiral MOFs to fabricate two new biocomposites (UiO-66@Np@CRL and UiO-66@Ib@CRL) as effective biocatalysts, which enable significant enhancement in the catalytic activity and enantioselectivity of lipase. The FTIR, SEM, EDX, TGA, and PXRD analyses were carried out to confirm the formation of the biocomposites. The catalytic performances of the biocomposites (UiO-66@Np@CRL and UiO-66@Ib@CRL) were evaluated in the typical hydrolysis of p-nitro-phenyl palmitate (p-NPP) and the catalytic enantioselective hydrolysis of (R,S)-naproxen methyl ester. Under optimal conditions, UiO-66@Np@CRL showed a higher enantiomeric excess of the substrate (ees) value and a 98 % and 50 % conversion rate, respectively, than that of UiO-66@Ib@CRL. Besides, an excellent enantioselectivity (E) value of 458 was obtained in the presence of the biocomposite (UiO-66@Np@CRL). In addition, it was observed that the catalytic activity, conversion rate and ees value of this composite (UiO-66@Np@CRL) remained almost unchanged in reuse after 6 months. The results showed that in enantioselective reactions, the highest conversion and enantioselectivity could be achieved when the chiral compound bound to the MOF and the model compound used are the same.

Synergistic enhancement of Co doped Ni/NiOx nanofilms for catalytic hydrolysis towards ammonia borane

Transition metal catalysts exhibit a potential application for the hydrolytic dehydrogenation of ammonia borane (AB). The regulation of active sites through heterogeneous metal doping have been acknowledged as an efficient technology. Herein, Co-doped Ni/NiO nanofilms (Ni/NiCoOx-Y, Y is Co/(Co + Ni) atom ratio) were synthesized on an ionic liquid (IL)/water interface, in which Co atoms are uniformly doped in the basal NiO crystal lattice in the form of Co ions. The Ni/NiCoOx-Y catalysts exhibit a “volcanic” relationship between the catalytic activities for AB hydrolysis and Co-doped content. The optimized Ni/NiCoOx-20 nanofilms exhibit observably enhanced catalytic activity for AB hydrolysis, completely producing H2 within 4 min with a turnover frequency of 12.93 molH2·molmetal−1·min−1 and a low activation energy of 39.57 kJ mol−1. Moreover, Co doping can effectively enhance the stability of Ni-based nanofilms. The incorporation of Co ions into Ni/NiO crystal lattice slightly increases Ni electron density or Ni lattice expansion. Thus “electronic effect” strengthens the adsorption of H2O/intermediates and further beneficially accelerate combination of AB and H2O molecules, contributing to the improved catalytic activity. Meantime, the strong interaction of Co–Ni atoms can utilize the synergistic enhancement effect.

Mechanistic insights into facet-dependent catalytic hydrolysis of organophosphate ester by α-MnO2 nanorods

Organophosphate esters (OPEs) are a class of new pollutants with high health and ecological risks, and metal oxide nanoparticles can catalyze their hydrolytic degradation. Yet, the mechanisms dictating how the intrinsic structural properties of metal oxide nanomaterials affect their catalytic activity remain elusive. Herein, we explore the mechanisms through which exposed facets of α-MnO2 nanorods determine their efficiency in catalyzing hydrolysis of 4-nitrophenyl phosphate (pNPP), a model OPE, using in situ spectroscopy and theoretical calculations. Facet-dependent catalytic activity was observed: α-MnO2 nanorods predominantly exposed with the {110} facet exhibited superior adsorption performance and hydrolysis efficiency to those predominantly exposed with the {310} and {200} facets. Surface unsaturated Mn atoms regulate the adsorption affinity of α-MnO2 for pNPP by influencing the coordination complexation strength. This inner-sphere complexation process activates the ester group, promoting the cleavage of the P–O bond and accelerating the hydrolysis reaction. Additionally, facets with higher Lewis acidity induce more pronounced electron redistribution in pNPP, which increases the electrophilicity of the P atom, making it more susceptible to nucleophilic attack and thus facilitating hydrolysis. The findings help predict the environmental fate and risks of OPEs and provide a basis for designing efficient catalytic nanomaterials for their removal.

Nitrogen-Rich Molybdenum Nitride with Intrinsic CD39 Nucleotidase Activity.

CD39 is one of the important nucleotidases to adjust extracellular adenosine triphosphate (ATP) and adenosine diphosphate (ADP) concentration. However, the enzyme mimics to simulate the activity of CD39 still remains to be explored. Herein nitrogen-rich molybdenum nitride (Mo5N6) nanosheets are explored to possess CD39-like activity, which are able to catalyze the hydrolysis of the high-energy phosphate bonds (HEPBs) in ATP and ADP but not the common phosphate bonds in adenosine monophosphate (AMP). The catalytic hydrolysis of the phosphate bond over Mo5N6-700 nanosheets is first investigated using para-nitrophenyl phosphate as the model substrate and then the CD39-like activity is further explored and verified by 31p NMR spectroscopy. Mo4+ on the surface of Mo5N6-700 nanosheets are the catalytic active sites. Using ATP as the model substrate, the Km and Vmax values of CD39-like activity at optimal pH 9.0 are 3.2µmol L-1 and 18.5µmol L-1 h-1, respectively. The CD39-like activity of Mo5N6-700 nanosheets enabled the down-regulation of intracellular ATP concentration to a larger degree for cancer cells than normal cells, which makes Mo5N6-700 nanosheets a potential therapeutic reagent for cancers.

Catalytic hydrolysis of COS over unsupported Al2O3: New insights into the influence of hydroxyl characteristics on hydrolysis efficiency

H2O molecules are challenging to dissociate at low temperatures to produce hydroxyl groups for heterogeneous carbonyl sulfide (COS) hydrolysis. Utilizing the inherent hydroxyl groups on Al2O3 surfaces for catalytic COS hydrolysis is effective; however, the relationship between the hydroxyl nature and hydrolysis efficiency remains unclear. In this study, we investigated the effects of crystal structure, surface morphology, specific surface area, and hydroxyl characteristics of Al2O3 on COS hydrolysis efficiency. Results showed that the content, stability, and activity of hydroxyl groups significantly impacted the efficiency. Catalysts prepared from commercial alumina (Al2O3-C) exhibited superior COS hydrolysis efficiencies under both dry and humid conditions compared to pseudo-boehmite derived Al2O3 (Al2O3-S) and boehmite derived Al2O3 (Al2O3-B) owing to the higher, more stable, and active hydroxyl content in Al2O3-C. Although Al2O3-S contained a sufficient amount of surface hydroxyl, its lower activity reduced the hydrolysis efficiency. The catalytic COS hydrolysis mechanism over hydroxyl-rich Al2O3 was elucidated through various characterization methods, providing new insights into the correlation between Al2O3 surface hydroxyl properties and COS hydrolysis efficiency.

Synthesis of Ecofriendly Bimetallic Pt/Ni Nanoparticles on KNbO3 via Hydrothermal Process for Sustainable Hydrogen Evolution from NaBH4

The performance of nickel and platinum bimetallic nanoparticles (NPs) supported on potassium niobate (KNbO3) is evaluated in the catalytic hydrolysis of sodium borohydride (NaBH4) to generate hydrogen (H2). KNbO3 was synthesized via a hydrothermal route using Nb2O5 and KOH as precursors. X-ray diffraction (XRD) confirmed the crystalline orthorhombic structure of KNbO3. The Ni/Pt NPs, with an average size of 4.66 nm and a spherical morphology, were uniformly dispersed on the surface of KNbO3 nanosheets. The N2 physisorption isotherms of KNbO3 and Ni/Pt NPs were classified as type V with H3 hysteresis, showing specific surface areas of 0.170 and 2.87 m2 g−1, respectively. Catalytic performance studies examined various Ni/Pt molar ratios, with the 1:3 ratio (mol/mol) demonstrating the highest efficiency. Kinetic analysis of NaBH4 hydrolysis showed that the data fit the pseudo-first-order model. An increase in temperature enhanced the hydrogen generation rate (HGR), reaching 2068.3 mL gcat−1 min−1 at 315.05 K. The apparent activation energy (Ea) was determined to be 29.9 kJ mol−1. Durability assays showed only an 11% decrease in activity after 11 catalytic cycles. Thus, a promising, easy-to-synthesize, and environmentally friendly catalyst for NaBH4 hydrolysis has been developed.

Ruthenium-Based High-Entropy Alloys Expediting Hydrogen Evolution through Catalytic Hydrolysis of Ammonia Borane

Ruthenium-Based High-Entropy Alloys Expediting Hydrogen Evolution through Catalytic Hydrolysis of Ammonia Borane

Catalytic Hydrolysis of Paraoxon by Immobilized Copper(II) Complexes of 1,4,7-Triazacyclononane Derivatives.

Organophosphate neuroactive agents represent severe security threats in various scenarios, including military conflicts, terrorist activities and industrial accidents. Addressing these threats necessitates effective protective measures, with a focus on decontamination strategies. Adsorbents such as bentonite have been explored as a preliminary method for chemical warfare agent immobilization, albeit lacking chemical destruction capabilities. Chemical decontamination, on the other hand, involves converting these agents into non-toxic or less toxic forms. In this study, we investigated the hydrolytic activity of a Cu(II) complex, previously studied for phosphate ester hydrolysis, as a potential agent for chemical warfare decontamination. Specifically, we focused on a ligand featuring a thiophene anchor bound through an aliphatic spacer, which exhibited high hydrolytic activity in its Cu(II) complex form in our previous studies. Paraoxon, an efficient insecticide, was selected as a model substrate for hydrolytic studies due to its structural resemblance to specific chemical warfare agents and due to the presence of a chromogenic 4-nitrophenolate moiety. Our findings clearly show the hydrolytic activity of the studied Cu(II) complexes. Additionally, we demonstrate the immobilization of the studied complex onto a solid substrate of Amberlite XAD4 via copolymerization of its thiophene side group with dithiophene. The hydrolytic activity of the resultant material towards paraoxon was studied, indicating its potential utilization in organophosphate neuroactive agent decontamination under mild conditions and the key importance of surface adsorption of paraoxon on the polymer surface.

Ratiometric electrochemical detection of alkaline phosphatase based on SWCNTs/Cu-MOF modified graphite paper electrodes

Alkaline phosphatase (ALP) is integral to a diverse array of biological processes, consequently, its presence is frequently linked to the onset of various pathologies. In the current investigation, 1-naphthyl phosphate (1-Npp) served as a substrate, with the catalytic hydrolysis of phosphate groups by ALP being leveraged to engender a detectable current at an applied potential of 0.277 V. Initially, carbon nanotubes (SWCNTs) were deposited via drop-coating onto graphite paper (Gp), a material characterized by exceptional electrical conductivity. Subsequently, Cu-MOF was uniformly deposited on Gp/SWCNTs composites by rapid electrodeposition technique, that is, chronocurrent method (i–t), at a potential of −1.1 V for 240 s, thereby fabricating an electrochemical sensor platform denominated Gp/SWCNTs/Cu-MOF. This platform enabled the ratiometric electrochemical quantification of ALP, utilizing the signal from Cu-MOF as an internal standard. This platform’s integrated design facilitates signal amplification and provides an inbuilt reference, which was instrumental in mitigating the impact of environmental fluctuations and enhancing the precision of the obtained data. The ratiometric signals exhibited strong linear correlations within the 0.014–14.29 U mL−1 concentration, with a detection limit of 0.005 U mL−1. Moreover, the sensor exhibited robust selectivity, repeatability, and excellent detection performance in real-world samples, with recovery rates spanning 99.3 %–103.5 %, making it a suitable candidate for the expedient and precise quantification of ALP in serum.

Magnetite Fe3O4 nanoparticles impregnated on Chlorella vulgaris microalgae: Its role in obtaining hydrogen from the sodium borohydride-hydrolysis

Recently, the single-celled green freshwater microalgae species “Chlorella vulgaris” has attracted the attention of researchers due to its different usage areas. In particular, research focuses on the technology of obtaining bio‑hydrogen with various techniques. This research involves, for the first time, the use of the microalga Chlorella vulgaris as a bio-supporting material for magnetite Fe3O4 nanoparticles (Fe3O4NPs@Chlorella vulgaris) and the production of hydrogen through catalytic hydrolysis of NaBH4 (sodium borohydride, SB) in the presence of the resulting magnetite nanoparticles. Here, detailed kinetic studies were carried out during the SB-hydrolysis by taking magnetite Fe3O4NPs@Chlorella vulgaris and SB in varying amounts and at varying temperatures, and the activation energy and lifetime of magnetite Fe3O4NPs@Chlorella vulgaris was found to be 23.49 kJ mol−1 and 93,280 mol H2 (mol Fe3O4)−1, respectively. No change in the chemical and physical structure of the biocatalyst was observed during the hydrolysis of SB, so only detailed characterization of microalgae and magnetite Fe3O4NPs@Chlorella vulgaris was performed, and the particle size of the catalyst was calculated as 10.19 ± 2.17 nm. The results showed that these Fe3O4NPs@Chlorella vulgaris, which can be easily separated magnetically and have high catalytic activity, are a “clean” and quite surprising catalyst in terms of hydrogen production.

Catalytic hydrolysis of HCN on the coupled sites of Lewis acid and surface hydroxyl of Fe-BEA catalyst leading to the presence of HCHO positively affects NH3-SCR activity

Formaldehyde (HCHO) in the exhaust gas of diesel or natural gas engines is usually considered to be a serious hindrance to the NH3-SCR process. However, the promotion effects of HCHO on the NH3-SCR activity and its temperature dependence were discovered in this work for the first time. For the Fe-BEA catalysts, below 300 °C, a notable decrease in activity observed, up to 40 % at 300 °C, and HCN selectivity reached 35 %. However, with the increase in temperature, a significant promotion effect was produced. Not only for the increase of NOx conversion, but also the diminish of the by-product HCN. The disparity in the number and activity of Lewis acid sites (Fe3+) and surface hydroxyls was the primary reason why Fe-BEA catalysts with varying Fe contents exhibited different influence. The presence of HCHO resulted in a modification of the oxidation pathway of NH3 at high temperatures. Surface hydroxyls facilitated the hydrolysis reaction of the as-formed HCN to produce NH3, with NH3 on Lewis acid sites subsequently re-participating in the SCR process. This enhanced the NOx conversion and the selectivity of carbon-containing products. Furthermore, it was demonstrated that HCHO completely converted to hexamethylenetetramine (HMTA) by reacting with NH3 prior to passing through the SCR catalyst. The thermal decomposition of HMTA on the catalyst was identified as a crucial step for the subsequent generation of HCN, and the detailed mechanism of how to effectively inhibit the decrease of de-NOx activity and the formation of HCN in the HCHO-containing NH3-SCR conditions was elucidated. This study paves the way for the development of effective SCR catalysts for the synergistic control of HCN from mobile and stationary sources.

Investigation of hydrolysis of sugarcane bagasse into glucose over solid acid HSO3-ZSM-5 zeolite for fermentation to bioethanol

ABSTRACT In the pursuit of sustainable energy sources, biomass has emerged as a promising alternative to fossil fuels due to its renewability and carbon neutrality. This current work presents the application of solid acid zeolite catalyst for biomass hydrolysis into reducing sugar for fermentation. Sulfonated ZSM-5 zeolite was prepared by grafting sulfonic acid group on the surface and/or into the pores of porous ZSM-5 zeolite and characterized by several analyses. The as-synthesized HSO3-ZSM-5 zeolite was then investigated as a solid acid catalyst for the hydrolysis of alkaline pretreated sugarcane bagasse (SB). Containing sulfonic acid groups – a very strong acid – on the surface, HSO3-ZSM-5 zeolite presented high catalytic activity and high efficiency in the hydrolysis of SB biomass. When the hydrolysis was carried out under optimal conditions, approximately 106.8 g/L of reducing sugar including of glucose, xylose, arabinose, and cellobiose was recovered. 86.65% fermentable sugars could be achieved after catalytic hydrolysis, and 48.7% of SB in total was converted to reducing sugar and others. Moreover, this solid acid catalyst can be reused impressively several times with no significant loss in catalytic activity. The sugar hydrolyzate could be used for fermentative production of bio-ethanol. Results indicated the possibility of using solid acid zeolite in the hydrolysis of lignocellulose to generate sugars that can be further applied in biofuel or chemical manufacturing.

Pt–Ni–Co trimetallic nanoparticles anchored on graphene oxide: An effective catalyst for ammonia-borane hydrolysis and direct electrooxidation of ammonia-borane in alkaline solution

In this study, graphene oxide supported platin, nickel and cobalt trimetallic nanoparticles (PtNiCo@GO) were prepared by the impregnation/reduction method. The catalytic performances of PtNiCo@GO catalysts prepared with different atomic ratios were investigated for hydrogen production and electro-oxidation of ammonia-borane (AB). For hydrolysis of ammonia-borane, Pt0.8Ni0.1Co0.1@GO catalyst exhibited higher catalytic activity than Pt0.6Ni0.2Co0.2@GO, Pt0.4Ni0.3Co0.3@GO, and Pt0.2Ni0.4Co0.4@GO. The hydrogen generation rate and turnover frequency values were found to be 540 mL min−1g−1 and 42.8 min−1, respectively, in the experiment conducted at 35 °C, 0.5 mmol AB, and 50 mg Pt0.8Ni0.1Co0.1@GO catalyst. The activation parameters (Ea, ΔH#, and ΔS#) in the catalytic hydrolysis of AB were obtained at 42.22 kJ/mol, 31.95 kJ/mol and −114.82 J/(mol × K), respectively. The effects of the PtNiCo@GO catalyst on AB electro-oxidation were made at a scanning rate of 100 mV/s in the potential range of - 1V/+1V against Ag/AgCl, and chronoamperometry measurements were made at constant potentials of - 0.2V, 0.1V and 0.4V. For cyclic voltammetry and chronoamperometry measurements, 5 mM [Fe(CN)6]3/4 (1 M KCl) redox probe and 1 M NaOH + 50 mM AB solution were used.

Study of the Sodium Borohydride Hydrolysis Reaction's Performance via a Kaolin-Supported Co-Cr Bimetallic Catalyst

Hydrogen is an attractive source of energy because of its properties, which include superior quality, effectiveness, pureness, dependability, and sustainability. Technologies for producing and storing hydrogen are being developed in parallel with fuel cell development. Chemical storage of hydrogen in a metal hydride containing boron eliminates the problem of hydrogen transportation and storage. Through catalytic reactions, hydrogen stored in solid form in boron hydrides can be recovered. In this study, a nowel developed Co-Cr bimetallic catalyst supported by kaolin, a natural mineral, was synthesized to be used for hydrogen production by hydrolysis of sodium boron hydride. The structural characteristics of the produced Co-Cr@Kaolin catalyst were ascertained by EDX, FTIR, and SEM analyses. Next, the ideal conditions for the hydrolysis reaction of sodium borohydride (NaBH4) catalyzed by Co-Cr@Kaolin were examined. These included the concentration of the catalyst, the amount of support material (kaolin), the amount of catalyst, and the concentration of NaBH4. The optimal hydrolysis conditions were found to be 2.5% NaOH concentration, 40 mg of catalyst, and 2% NaBH4 concentration at 303 K. The maximum rate of hydrogen production was determined as 5007 ml g-1 min-1 under optimal conditions. After conducting hydrolysis operations at different temperatures to elucidate the reaction kinetics, it was found that the catalytic hydrolysis reaction was of the 0th order and that the reaction activation energy was 19.36 kJ mol-1. The hydrogen production rate obtained as a result of the hydrolysis reaction accompanied by a Co-Cr catalyst was determined as 3166 ml g-1 min-1. It is therefore established that supporting kaolin to Co-Cr catalyst enhances its efficacy.

Bi-functional hydrogen tungsten bronze/carbon composite catalysts towards biomass conversion and solar water purification

We presented a novel bi-functional catalyst composed of HxWO3 and carbon composites, which exhibits excellent catalytic activity in biomass conversion and has the ability to effectively purify water via a wide range of wavelengths in the light spectrum. The HxWO3/carbon composites were effectively produced from commercially available monoclinic tungsten trioxide (WO3) and polypropylene (PP) powders to a single-step mechanochemical reaction employing high-energy ball milling. We systemically investigated how different synthesis parameters, such as rotation speed, processing duration, and ball diameter, affect the mechanochemically-induced phase transformation to either tetragonal or cubic HxWO3 during planetary ball milling. The crystal phase of HxWO3 was controllable by altering the total impact energy in the ball milling. In addition, real-time monitoring of the pressure increment inside the pot and evaluation of the evolved gas revealed the degassing behavior through the oxidative degradation of PP assisted by WO3. The CV and Rietveld analysis proved that HxWO3 exhibited significant enhancement by two orders of magnitude in the rate of H+ diffusion compared to monoclinic WO3. This enhancement would be attributed to the expansion of a mechanically-formed tunnel along the a-axis, which facilitates the migration of H+ ions. The HxWO3/carbon composites performed approximately 12-fold higher efficiency in generating soluble solids (glucose and furfural derivatives) compared to untreated WO3 through the catalytic hydrolysis of cellulose, owing to the enhanced Brønsted acidity. Moreover, the composite particles showed broad light absorption in the UV–Vis–NIR range and demonstrated a considerable enhancement of over three orders of magnitude in the photocatalytic degradation of methyl orange pollutants when exposed to NIR and visible light.

Construction of La/Al2O3 nanorod-like catalyst with rich basic sites: Enabling efficient conversion of COS-superior selectivity and theoretical insights

The introduction of surface basic sites to COS hydrolysis catalysts can improve H2O activation and COS adsorption, leading to enhanced catalytic performance. However, maximizing the concentration of basic sites remains a challenge due to the limited exposed surface area of these catalysts. Herein, a La/Al2O3 catalyst with abundant alkaline sites to catalyze the hydrolysis of COS was prepared by a simple ammonia-assisted hydrothermal method. This synthesized La/Al2O3 catalyst exhibits a thin rod-like structure formed by the random accumulation of nanoparticles. Lanthanum, one of the most abundant rare earth metals, is an ideal doping aid to further promote the COS-catalyzed hydrolysis performance of Al2O3. Characterization studies show that the proper lanthanum loading effectively enhances the formation of basic sites, leading to improved lattice oxygen reactivity and –OH adsorption capacity. As a result, the prepared La-loaded Al2O3 nanorod sample with abundant basic sites exhibits nearly 100 % COS conversion and total H2S yield at 160 °C. In addition, the reaction pathways and deactivation mechanisms for selective catalytic hydrolysis of COS on the La-doped Al2O3 catalyst were revealed by using in situ DRIFTS to evaluate COS adsorption and hydrolysis. Density functional theory calculations showed that La loading enhances the electron transfer between the La and Al atoms, improves the formation of basic sites, and enhances the adsorption of –OH. This study provides new insights into the design of efficient alumina-based catalysts for the catalytic hydrolysis of COS.

Enhanced stability in Co0.8Ni0.2/NDMCS catalysts: Carbon nitride encapsulation for robust hydrogen generation

Catalytic hydrolysis of NaBH4 is a promising method for "on-demand" hydrogen generation, with cobalt catalysts playing a key role due to their high hydrogen generation rates. However, rapid cobalt dissolution and poor recycling hinder stable hydrogen production. This study presents a dual-mode stabilization technique using carbon nitride encapsulation to address these challenges. Co0.8Ni0.2 alloy nanoparticles (NPs) are confined within N-doped mesoporous carbon spheres (NDMCS) and encapsulated with a carbon nitride shell (∼ 5 nm thick). XPS results reveal strong non-classical metal-support interaction, increasing activation energy from 38.82 to 44.6 kJ mol−1, which controls cobalt's reactivity, leading to excellent recycling efficiency (90 % retention of initial rate, no change in particle size) in high-concentration reactants (2 %NaBH4 + 2 %NaOH). The retention rate drops to 26.8 % without this stabilization due to rapid metal dissolution. This stability of Co0.8Ni0.2 alloy in alkaline conditions has significant practical implications for hydrogen generation and other electrochemical applications.

Ruthenium nanoparticle immobilised on ionic liquid polymer as efficient catalyst for the hydrolysis of NaBH4

Development of heterogeneous catalyst is significant key for achieving high performance of NaBH4 hydrolysis to produce hydrogen. The stability of sodium borohydride in the presence of suitable catalyst is the efficient method to generate hydrogen. In this work, styrene-imid PIILP, polymer 1 decorated styrene, imidazolium ionic liquid, and cross-coupling is successfully synthesised by AIBN initiated radical polymerisation, then precipitation with 3,3′,3″phosphinetriyltribenzene sulfonate with ratio (1:0.3) to isolate the first styrene-imid- sulphonated PIILP, polymer 2. RuNP@styrene-imid-sulphonated PIILP, RuNPs catalyst 3 was synthesised by impregnation with RuCl3, then reduction by NaBH4. Moreover, several analytical techniques such as, 31P, 1H, 13C solid-state NMR, CHN, IR, XPS, TEM, TGA-DTA, and SEM were examined to explore the obtained catalyst 3. The hydrogen generation from NaBH4 utilizing catalyst 3 was exhibited the catalytic behaviour studying several parameters such as, temperature, catalytic loading, and NaBH4 concentrations this work was deducted the activation energy (30.32 kJmol-1), and the turnover frequency (TOF) reached up 134.9, 112.77, and 98.38 moleH2.molcat−1.min−1 at 40, 35 and 30 °C. The effectiveness of Ruthenium nanoparticle catalyst 3 for the hydrolysis reaction of NaBH4 was examined in H2O and D2O resulting kinetic isotope effect (KIE) kH/kD = 3. In addition, RuNPs demonstrated a promising efficient for reuse catalyst 3 after five cycles for the catalytic hydrolysis.

Effect of mixed metal oxide‐based catalysts for the removal of hydrophobic phthalates from water

AbstractContaminants of emerging concern (CECs) such as phthalic acid esters (PAEs) are ubiquitous, toxic and persistent in aquatic environments. Current study explored mixed metal oxide catalysts derived from magnesium aluminium (MAH), magnesium aluminium ruthenium (MAR‐H), magnesium aluminium nickel (MANH) hydroxides and copper aluminium hydroxides of ammonium (CAM‐Am) and sodium molybdate (CAM‐Na) to remove dibutyl phthalate (DBP) and di‐2‐ethyl hexyl phthalate (DEHP) from water. Powder X‐ray diffraction (XRD) studies of the catalysts before and after the treatment showed that their structures were stable and robust. During Fourier Transform Infrared (FTIR) studies, vibrational bands or peaks of ester and alkane functional groups of DBP and DEHP were observed at all the catalysts after treatment. Thermogravimetric analysis (TGA) confirmed phthalate adsorption at the five catalysts. Hydrolysis of DBP and DEHP was observed during treatment using CAM‐Am and CAM‐Na that was analysed and quantified using total organic carbon (TOC), high performance liquid chromatography (HPLC) and high‐resolution mass spectrometry (HRMS). From TOC analyses, optimal conditions of 500 mg L−1 catalyst dosage and 30 h treatment time were deduced for catalytic hydrolysis of DBP and DEHP. Present study illustrated that the catalysts MAH and MANH can adsorb PAEs while CAM‐Na can adsorb and hydrolyse them.