Catalytic Activity For Hydrolysis Research Articles

Boosting catalytic hydrolysis of carbonyl sulfide over K+ modified CeO2 nanospheres at low-temperature

Carbonyl sulfide (COS) as one of typical atmospheric sulfur-containing pollutants widely emitted from various industrial processes, which has a significant impact on human health and environmental safety. Currently, developing highly efficient catalysts to eliminate COS is of great significance for both fundamental catalytic research and actual industrial application. Here we report a series of K+ doping spherical cerium oxide (CeO2-S) that showing promote activity for catalytic hydrolysis of COS. The research results demonstrated that the K+-doped CeO2-S formed more Ce3+ and oxygen vacancies than CeO2-S. The hydrolysis activity and stability of CeO2-S for COS were significantly improved by the introduction of K+. Among them, the 0.2 K/CeO2-S showed the optimal performance. Further in-situ DRIFTS results revealed that a slight increase in alkalinity could enhanced the activation of H2O over 0.2 K/CeO2-S, and the generated surface active hydroxyl groups reacted with adsorbed COS to produce the intermediate species (HSCO2-), leading to the formation of H2S and CO2. The catalysts prepared in this paper exhibited promoted activity with low-temperature and high stability for COS hydrolysis, which is beneficial for practical industrial scale-up applications and provides novel insights into designing efficacious catalysts with efficient low-temperature activity and superior stability for removing COS.

Enhancing catalytic hydrolysis activity of ZnNiAl hydrotalcite-like compounds-derived oxides using rare earth metals

Efficient catalysts are highly desirable for the simultaneous removal of hydrogen cyanide (HCN) and carbonyl sulfide (COS) to meet the increasingly stringent emission standards and achieve cleaner production. In this study, ZnNiAl hydrotalcite-like compounds (HTLCs)-derived oxides doped with a series of rare earth metals, such as cerium (Ce), gadolinium (Gd), and yttrium (Y), were synthesized and used for the simultaneous hydrolysis of HCN and COS. The results demonstrated that the chemical state and electronic structure of ZiNiAl were changed by Ce doping because of the incorporation of Ce into the nickel oxide (NiO) network. Thus, abundant active species for the adsorption and dissociation of HCN and COS, including chemically adsorbed oxygen and strong basic sites, were produced by Ce doping. Meanwhile, the well-developed mesoporous structure provided accessibility to the active sites. As a result, Ce doping significantly enhanced the catalytic performance of ZnNiAl. Furthermore, the mechanisms of HCN and COS hydrolysis over Ce-ZnNiAl and their deactivation were proposed. This study provides a novel route for efficiently eliminating HCN and COS in diverse industrial processes.

Removal of organophosphorus agents via atomically dispersed Co on nitrogen-doped graphene: catalytic degradation and adsorption.

In this work, we disperse Co atomically on three-dimensional networks of N-doped graphene (3DNG) through the impregnation of 3DNG with Co(Ac)2·4H2O solution followed by rapid pyrolysis. The structure, morphology and composition of the as-prepared composite, namely ACo/3DNG, are characterized. The atomically dispersed Co and enriched Co-N species afford the ACo/3DNG with unique catalytic activity for hydrolysis of organophosphorus agents (OPs), and the network structure and super-hydrophobic surface of 3DNG ensures excellent physical adsorption capacity. Thus, ACo/3DNG demonstrates good capability for removal of OPs pesticides from water.

Enhancement of catalytic hydrolysis activity for organophosphates by the metal–organic framework MOF-808-NH2via post-synthetic modification

Post-synthetic modification of MOF-808 creates solid state buffering capacity for organophosphate catalytic hydrolysis.

Thermo-responsive catalysts based on bimetallic alloyed Pt-Pd supported on mesoporous silica: Controllable hydrogen generation from ammonia borane

The ultrafine and highly dispersed bimetallic Pt-Pd nanoparticles are successfully anchored on mesoporous silica nanoparticles (MSN). The [email protected] catalyst exhibits excellent catalytic performance in the hydrogen from ammonia borane (AB). When the [email protected] nanoparticles were grafted with luminescent material and smart thermo-responsive polymer, a smart catalyst could be fabricated. The smart catalyst exhibits the thermo-responsive catalytic performance and switchable luminescence. For example, the composite catalyst displays high catalytic activity in hydrolysis of AB at 25 °C. However, it shows much lower catalytic activity when the temperature increases to 35 °C. The smart catalysts could be potentially applied in the self-protection device of dehydrogenation. When the system of dehydrogenation is under high temperature environment, the smart composite catalyst could automatically restrain the production of H2 for the purpose of safety.

The optimized biocatalytic synthesis of (S)-methyl 2-chlorobutanoate by Acinetobacter sp. lipase.

Epilepsy is a chronic disease caused by sudden abnormal discharge of brain neurons, leading to transient brain dysfunction. Levetiracetam, developed by the UCB company in Belgium, is an effective drug for the treatment of epilepsy. (S)-Methyl 2-chlorobutanoate is an important chiral building block of levetiracetam, which has attracted a great deal of attention. In this study, a strain of lipase-produced Acinetobacter sp. zjutfet-1 was screened from soil samples. At optimized conditions for fermentation and biocatalysis, the bacterial lipase exhibited high catalytic activity for hydrolysis and stereoselectivity toward racemic methyl 2-chlorobutanoate. When the enzymatic reaction was carried out in 6% of racemic substrate, the enantiomeric excess (e.e.s ) reached more than 95%, with a yield of over 86%. Therefore, this lipase can efficiently resolve racemic methyl 2-chlorobutanoate and obtain (S)-methyl 2-chlorobutanoate, which presents great potential in the industrial production of levetiracetam.

Silica@lipase hybrid biocatalysts with superior activity by mimetic biomineralization in oil/water two-phase system for hydrolysis of soybean oil

Enzymatic hydrolysis of vegetable oils is crucial for its potential application in foods and drugs. However, the poor activity of free lipase hinders the reaction. Herein, inspired by lipase interface activation, a novel silica@lipase hybrid biocatalyst with a superior catalytic activity for hydrolysis of vegetable oils was developed though the sol-gel biosilicification approach in the oleic acid/water two-phase system. The resultant silica@lipase hybrid biocatalyst exhibited 13.5-fold higher activity than free lipase, and excellent storage stability. After 100 days of storage, the free lipase absolutely loss hydrolytic activity whereas the silica@lipase hybrid biocatalyst still retained 197.4% of its initial activity. In particular, hydrolysis yield of soybean oil by the hybrid biocatalyst reached 98.8% within only 4 h, which is the fastest value recorded in the current literature. After 5 consecutive cycles, hydrolysis yield still retained up to 63%. Therefore, this strategy provides a facile and efficient method for preparing lipase hybrid biocatalysts with high hydrolysis activity.

Highly dispersed cobalt nanoparticles onto nitrogen-doped carbon nanosheets for efficient hydrogen generation via catalytic hydrolysis of sodium borohydride

Porous carbon nanostructures are promising supports for stabilizing the highly dispersed metal nanoparticles and facilitating the mass transfer during the reaction, which are critical to achieve the high efficiency of hydrogen generation from sodium borohydride dehydrogenation. Herein, the catalytically active porous architectures are simply prepared by using 2-methylimidazole and melamine as reactive sources. The structural and compositional characterizations reveal the coexistence of metallic cobalt and N-doped carbon in porous architectures. Electron microscopy observations indicate that the synthesized products are smartly constructed from the carbon nanosheets with densely dispersed Co nanoparticles. Due to the notable structural features, the prepared Co@NC-600 sample presents the highly efficient activity for catalytic hydrolysis of NaBH4 with a hydrogen generation rate of 2574 mL min−1 gcat−1 and an activation energy of 47.6 kJ mol−1. The catalytically active metallic Co and suitable support-effect of N-doped carbon are responsible for catalytic dehydrogenation.

Synergetic effect between Fe and Ti species on Fe–Ti–O x for hydrogen cyanide purification

ABSTRACT The Fe–Ti–O x catalysts with the different Fe contents were used for the catalytic hydrolysis of hydrogen cyanide (HCN) in the presence of H2O, which investigated the roles of Fe chemical valence and oxygen species in HCN removal and the production (NH3 and CO). The results implied that more amounts of Fe3+ species over Fe–Ti–Ox could increase the catalytic hydrolysis activity of HCN while Fe2+ species contributed to the formation of NH3 at high temperatures. Furthermore, the abundance of surface oxygen species was in favour of the catalytic performance of HCN.

Air-engaged fabrication of nitrogen-doped carbon skeleton as an excellent platform for ultrafine well-dispersed RuNi alloy nanoparticles toward efficient hydrolysis of ammonia borane

Functional carbons that can provide abundant anchoring sites for metal nanoparticles (NPs) have shown great promise in boosting the catalytic activity for hydrolysis of ammonia borane (AB), while the synthetic recipes for some of them are complicated, time-consuming and hazardous together with a low yield. Herein, we develop a facile and easily scalable one-pot synthetic strategy to nitrogen-doped carbon skeleton (NCS) via direct pyrolysis of ethylenediamine tetra-acetic acid tetra-sodium salt in air. Attributing to the anchoring sites from abundant nitrogen-dopant and nanoporous structure of NCS, ultrasmall RuNi alloy NPs are highly distributed on NCS. The as-prepared RuNi/NCS can be used as a highly active catalyst for hydrogen production from AB hydrolysis at room temperature. Specifically, the optimal Ru1Ni1.90/NCS delivers an excellent catalytic activity with a very high turnover frequency of 1017 min−1 in basic solution, superior to many previous results. The kinetic studies indicate that AB hydrolysis catalyzed by Ru1Ni1.90/NCS is first-order and zero-order in terms of Ru and AB concentrations, respectively. Additionally, the isotopic analysis reveals that the O–H bond cleavage of water is the rate-determining step. The high catalytic activity of Ru1Ni1.90/NCS can be assigned to the ultrasmall RuNi nanostructure, highly nanoporous carbon matrix, and abundant N-dopant and the synergistic catalysis between the two metals. This study offers a simple synthetic protocol for construction of metal-carbon hybrid toward hydrogen generation from the hydrolysis of chemical storage materials.

Nanostructured manganese oxides as highly active catalysts for enhanced hydrolysis of bis(4-nitrophenyl)phosphate and catalytic decomposition of methanol

The nanostructured manganese oxides (MnOx) exhibited high catalytic activities for hydrolysis of phosphate diester-based substrate bis(4-nitrophenyl)phosphate and decomposition of methanol to carbon monoxide and hydrogen as a potential alternative fuel.

Cobalt oxide supported multi wall carbon nanotube catalysts for hydrogen production via sodium borohydride hydrolysis

Cobalt oxide supported multi-wall carbon nanotubes (Co/MWCNTs) catalysts with different cobalt oxide loadings were synthesized by simple impregnation method. The synthesized Co/MWCNTs materials were used as catalysts for hydrolysis of sodium borohydride (NaBH4), an effective route to produce clean hydrogen. The effect of some parameters such as Co loading, reaction temperature and reaction time were investigated on the performance of catalysts in hydrolysis of NaBH4. The hydrogen generation rate was found to be 409 mLg−1min−1 at 35 °C for Co/MWCNTs-20 catalyst in NaBH4 hydrolysis, while it is 28 mLg−1min−1 for bulk MWCNTs support. The physico-chemical characteristics such as crystalline phase, morphology, particle size, reducibility, surface and textural properties of the catalysts were studied by using powder XRD, FE-SEM, TEM, N2-physorption, XPS and H2-TPR techniques. The reduction temperature of cobalt oxide species was shifted to lower temperatures after impregnation of nanosized Co oxides on the MWCNTs support. It was also observed that presence of more number of surface Co2+ species in Co/MWCNTs-20 catalyst is responsible for superior activity in catalytic hydrolysis of NaBH4. The obtained results also suggested that Co/MWCNTs catalysts can be reused for five cycles with a slight loss of activity.

Hydrolysis of Oligosaccharides and Polysaccharides on Sulfonated Solid Acid Catalysts: Relations between Adsorption Properties and Catalytic Activities.

Sulfonated solid acid materials, such as sulfonated carbon catalysts, are promising materials as heterogeneous catalysts for the hydrolysis of esters and polysaccharides in water solvents. The catalytic active site is a sulfonic acid functional group. Compared to conventional strong acidic ion-exchange resin catalysts, sulfonated carbon materials have less sulfonic acid functional groups but higher catalytic activity for hydrolysis of polysaccharides per catalyst weight. However, the details of catalytic properties and the substrate suitability of both catalysts are unclear. In this study, the hydrolytic activities and the adsorption properties of both catalysts were investigated for various oligosaccharides and polysaccharides with varying degrees of polymerization (DP). The catalytic activities for the hydrolysis with increase of the DP of saccharides were found to increase over the sulfonated carbon catalyst but decrease over strong acidic ion-exchange resin catalyst. The inverse catalytic properties attribute to the dependence of the amounts of adsorption and/or penetration of saccharides on the DP. Moreover, the catalytic activity per acidic sites of strong acidic ion-exchange resin is in good agreement with the value obtained by multiplying the catalytic activity of a dilute sulfuric acid by the penetration degrees.

Zhao Li

Zhao Li

Acidic and basic groups introducing on the surface of activated carbon during the plasma-surface modification for changing of COS catalytic hydrolysis activity

The Fe-based microwave coconut shell activated carbon (Fe/MCSAC) catalyst was surface modified by O2- and NH3-plasma. The catalyst modified by O2-plasma showed a lower catalytic activity than the unmodified sample, but the catalyst modified by NH3-plasma was improved dramatically. Fourier Transform Infrared Spectroscopy (FTIR) results showed that -COOH and -NH2 groups can be generated after by O2- and NH3-plasma modification, respectively. The theoretical calculation results indicated that acidic -COOH group showed some inhibition to the hydrolysis of carbonyl sulfide (COS), but -NH2 could improve it by bonding with the H atoms of H2O.

Co3xCu3-3x(PO4)2 microspheres, a novel non-precious metal catalyst with superior catalytic activity in hydrolysis of ammonia borane for hydrogen production

Development of robust and cheap catalyst for fast hydrogen evolution from ammonia borane (AB) aqueous solution is an interesting and important topic in the field of hydrogen energy. Herein, a novel non-precious Co3xCu3-3x(PO4)2 catalyst possessing high reactivity in AB hydrolysis has been developed for the first time. By tuning the molar ratio of Co and Cu, a series of Co3xCu3-3x(PO4)2 with different x were synthesized and the catalytic behavior in AB hydrolysis was examined. At the optimal x of 0.8, an ultrahigh turnover frequency of 72.6 min−1 was achieved. Additionally, the synergistic effect between Cu3(PO4)2 and Co3(PO4)2 was experimentally confirmed, and the reaction kinetics of AB hydrolysis catalyzed by Co2.4Cu0.6(PO4)2 were investigated. This work provides a simple route and some new insights for the fabrication of a cheap P-containing catalyst with robust catalytic performance.

Activated carbon derived from tea waste: A promising supporting material for metal nanoparticles used as catalysts in hydrolysis of ammonia borane

Activated carbons with high porosity and high surface area are promising materials to be used in wide-range applications. They can easily be prepared from various biomass source following by simple and reproducible activation and carbonization steps. In this study, the woody part of tea which is highly available tea waste after the harvesting of tea leaves is considered as the precursor of highly porous activated carbon. In fact, activated carbon with well-ordered porous structure (micropore area = 1614.3 m2 g−1, micropore volume = 1.13 cm3 g−1) and high surface area (2559 m2 g−1) was achieved using this tea waste. The obtained activated carbon was used to support cobalt, nickel and copper nanoparticles which were used as catalysts in H2 generation from aqueous ammonia borane. The results reveal that Co nanoparticles with an average particle size of 3.18 nm on activated carbon provide higher activity (TOF = 7.5 min−1) as compared to nickel (TOF = 4.8 min−1) and copper nanoparticles in this reaction. Herein, we report also the kinetic studies including the effect of temperature, metal concentration and metal loading on the catalytic activity in hydrolysis of ammonia borane.

Surface characterization of metal oxides-supported activated carbon fiber catalysts for simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide

The sol–gel method was used to synthesize a series of metal oxides-supported activated carbon fiber (ACF) and the simultaneous catalytic hydrolysis activity of carbonyl sulfide (COS) and carbon disulfide (CS2) at relatively low temperatures of 60°C was tested. The effects of preparation conditions on the catalyst properties were investigated, including the kinds and amount of metal oxides and calcination temperatures. The activity tests indicated that catalysts with 5 wt.% Ni after calcining at 400°C (Ni(5)/ACF(400)) had the best performance for the simultaneous catalytic hydrolysis of COS and CS2. The surface and structure properties of prepared ACF were characterized by scanning electron microscope-energy disperse spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), carbon dioxide-temperature programmed desorption (CO2-TPD) and diffuse reflectance Fourier transform infrared reflection (DRFTIR). And the metal cation defects were researched by electron paramagnetic resonance (EPR) method. The characterization results showed that the supporting of Ni on the ACF made the ACF catalyst show alkaline and increased the specific surface area and the number of micropores, then improved catalytic hydrolysis activity. The DRFTIR results revealed that -OH species could facilitate the hydrolysis of COS and CS2; -COO and -C–O species could facilitate the oxidation of catalytic hydrolysate H2S. And the EPR results showed that high calcination temperature conditions provide more active reaction center for the COS and CS2 adsorption.

Retraction: Honeycomb-like Co-B amorphous alloy catalysts assembled by a solution plasma process show enhanced catalytic hydrolysis activity for hydrogen generation.

Retraction of ‘Honeycomb-like Co–B amorphous alloy catalysts assembled by a solution plasma process show enhanced catalytic hydrolysis activity for hydrogen generation’ by Dong Ge Tong et al., RSC Adv., 2012, 2, 2369–2376.

Facile Synthesis of Monodispersed Co Nanoparticles on Titanium Carbides for Hydrolysis of Ammonia Borane at Mild Temperature.

Herein, we successfully immobilized non-noble Co nanoparticles on titanium carbides (MXene) for the hydrolysis of ammonia borane by a simple co-reduction route. The synthesized Co nanoparticles with the size of 3.2 nm were monodispersed on MXene surface. The Co NPs/MXene exhibited excellent catalytic performance for the hydrolysis of ammonia borane with TOF value of 39.9 molH₂ mol-1cat min-1 at 323 K. The enhanced catalytic property was mainly due to the ultrafine nanoparticles formed on MXene surface. More importantly, the catalytic activity for hydrolysis of ammonia borane did not significantly decrease for up to 6 recycling tests, indicating the remarkable reusability of Co NPs/MXene. Furthermore, this study opens up a new strategy for the preparation of non-noble metallic nanocatalysts with high performance for hydrolysis reactions in practical hydrogen storage systems, thereby fast-tracking the application of ammonia borane in fuel cells.