Special Issue on Catalytic Activation and Selective Conversion of Energy-Related Molecules

The activation and selective conversion of energy-related molecules is an important research area of energy chemistry.The depletion of petroleum has stimulated research activities into the utilization of non-petroleum carbon resources such as natural gas(including conventional and

Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes

Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment.

Understanding the Pt-like Catalytic Activity of Transition Metal Carbide Ta4C_(3) for I_(3)^(-) Reduction

This paper attempts to understand the Pt-like catalytic activity of transition metal carbide Ta4C_(3) for IRR(I_(3)^(-)reduction reaction)based on the correlation of adsorption energy to d-band center(εd).Ta4C_(3) was prepared by carbothermal reduction method with a template.Its photoelectrochemical properties were investigated as a CE(counter electrode)in DSSC(dye-sensitized solar cell).Its surface electronic structures,including DOS(density of state)andεd,and adsorption energy were computed by first-principle DFT(density functional theory).In TMC(transition metal carbide)Ta4C_(3),the interaction between Ta and C atoms makes the d-band of Ta broaden and results in the downward shift of itsεd.A moderate absorption energy corresponding to theεd is achieved,which is the nature of the Pt-like catalytic activity of Ta4C_(3).Appropriate change of adsorption energy by adjustingεd is a promising strategy to improve catalytic activity.This work is of great significance to the fundamental and application researches.

PREPARATION OF MESOPOROUS CARBON BY CARBON DIOXIDE ACTIVATION WITH CATALYST

A mesoporous activated carbon (AC) can be successfully prepared by catalytic activation with carbon dioxide. For iron oxide as catalyst, there were two regions of mesopore size distribution, i.e. 2-5nm and 30-70nm. When copper oxide or magnesium oxide coexisted with iron oxide as composite catalyst, the content of pores with sizes of 2-5nm was decreased, while the pores with 30-70nm were increased significantly. For comparison, AC reactivated by carbon dioxide directly was also investigated. It was shown that the size of mesopores of the resulting AC concentrated in 2-5nm with less volume. The adsorption of Congo red was tested to evaluate the property of the result-ing AC. Furthermore, the factors affecting pore size distribution and the possibility of mesopore formation were discussed.

Size-dependent peroxidase-like catalytic activity of Fe_3O_4 nanoparticles

Peroxidase-like catalytic properties of Fe3O4 nanoparficles （NPs） with three different sizes, synthesized by chemical coprecipitation and sol-gel methods, were investigated by UV-vis spectrum analysis. By comparing Fe3O4 NPs with average diameters of 11, 20, and 150 nm, we found that the catalytic activity increases with the reduced nanoparticle size. The electrochemical method to characterize the catalytic activity of Fe3O4 NPs using the response currents of the reaction product and substrate was also developed.

Catalytic properties of Cu/Co/Zn/Zr oxides prepared by various methods

The new Cu-Co based （Cu/Co/Zn/Zr） catalysts for higher-alcohol synthesis were prepared using coprecipitation method, plasma enhanced method and reverse coprecipitation method under ultrasound irradiation. The catalysts were investigated by the means of BET, SEM, XRD, H2-TPR and XPS. Catalytic properties of the catalysts prepared by various methods were examined using CO hydrogenation reaction. It was found that plasma enhanced method and reverse coprecipitation method under ultrasound irradiation were both effective in enhancing the catalytic properties of Cu/Co/Zn/Zr mixed oxides. The small particle size, high dispersion of active components, the improvement of specific surface area and surface contents of active phases could account for the excellent performance of the experimental Cu/Co/Zn/Zr catalysts.

Preparation of SO_4^(2-)/TiO_2-WO_3 solid superacid and its catalytic activity in acetalation and ketaltion

SO_4^(2-)/TiO_2-WO_3 was prepared and its catalytic activity under differentsynthetic conditions was discussed with esterification of n-butanoic acid and n-butyl alcohol asprobing reaction. The optimum conditions are found that the mass fraction of H_2WO_4 used in thecompound is 12.5 percent, the calcination temperature is 580 deg C, the calcination time is 3 h, andthe soaked consistency of H_2SO_4 is 1.0 mol centre dot L^(-1). Then SO_4^(2-)/TiO_2-WO_3 wasapplied as the catalyst in the catalytic synthesis of eight similar important ketals and acetalsunder the optimum conditions and revealed high catalytic activity. On condition that the molar ratioof aldehyde/ketone to glycol is 1:1.5, the mass fraction of the catalyst used in the reactants is0.5 percent, and the reaction time is 1.0 h, the yields of ketals and acetals can reach 64.2percent-95.1 percent. Moreover, it can be easily recovered and reused.

A Sub-Nanostructural Transformable Nanozyme for Tumor Photocatalytic Therapy

The structural change-mediated catalytic activity regulation plays a significant role in the biological functions of natural enzymes.However,there is virtually no artificial nanozyme reported that can achieve natural enzyme-like stringent spatiotemporal structure-based catalytic activity regulation.Here,we report a subnanostructural transformable gold@ceria(STGC-PEG)nanozyme that performs tunable catalytic activities via near-infrared(NIR)light-mediated sub-nanostructural transformation.The gold core in STGC-PEG can generate energetic hot electrons upon NIR irradiation,wherein an internal sub-nanostructural transformation is initiated by the conversion between CeO;and electron-rich state of CeO;-x,and active oxygen vacancies generation via the hot-electron injection.Interestingly,the sub-nanostructural transformation of STGC-PEG enhances peroxidase-like activity and unprecedentedly activates plasmon-promoted oxidase-like activity,allowing highly efficient low-power NIR light(50 m W cm;)-activated photocatalytic therapy of tumors.Our atomic-level design and fabrication provide a platform to precisely regulate the catalytic activities of nanozymes via a light-mediated sub-nanostructural transformation,approaching natural enzyme-like activity control in complex living systems.

Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

Surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

Catalytic combustion study of soot on Ce_(0.7)Zr_(0.3)O_2 solid solution

The Ce0.7Zr0.3O2 solid solution and CeO2 were prepared using the sol-gel method. The phase structure, crystallite sizes and the reducibility of the catalysts were characterized by XRD and H2-TPR techniques. XRD results indicated that Zr^4＋ had replaced part of Ce^4＋ to form a fluorite-like solid solution, which was favorable to obtain ultrafine nanoparticles. The ratio of main HE consumption for Ce0.7Zr0.3O2：CeO2 was 4.4：1.0, implying that the solid solution could improve the reducibility compared to the single CeO2. The Ce0.7Zr0.3O2 solid solution catalyst showed a sharp combustion peak at 397 ℃, which was 200 ℃ lower than that of the single soot. The good catalytic activity of the Ce0.7Zr0.3O2 was attributed to the formation of nano-CeO2-based solid solution, which enhanced the reducibility and then improved the combustion activity. As Ce0.7Zr0.3O2 could be easily reduced to Ce0.7Zr0.3O2-x meanwhile, after oxygenation, the Ce0.7Zr0.3O2.x was recovered to Ce0.7Zr0.3O2 completely. A catalytic combustion reaction mechanism was proposed： the Ce0.7Zr0.3O2 was reduced to Ce0.7Zr0.3O2-x by the reaction with carbon and then it was recovered to Ce0.7Zr0.3O2-x by the interaction with O2.

Theoretical Study on the Catalytic Activity and Sulfur Resistibility of Amorphous Alloy Ni-B-P

In the present paper, one hundred cluster models NinBP （n = 1-6） have been designed and studied by density functional theory （DFT） to get an insight into the local structure, catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found： that as the content of Ni in the clusters increases, the value of Fermi level in clusters fluctuated, which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS, we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP （n = 1 -6）, we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity, strong sulfur resistibility appears in clusters Ni3BP, and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future.

Effects of Dispersed Mo-Fe Catalysts on Catalytic Hydrothermal Conversion of Residue

Replacement of precious single metal catalysts with cost-effective,highly-dispersed composite catalysts for catalytic hydrothermal conversion of residue holds tremendous promise for the residue upgrading technologies.Organic metals were added to the feed as the oil-soluble precursors,and were transformed into the catalytic active phases in this work.Physical properties and structures of the composite catalysts had been investigated by X-ray fluorescence spectroscopy,X-ray photoelectron spectroscopy,X-ray diffraction,scanning electron microscopy and transmission electron microscopy.The composite catalysts were found to be highly efficient in the catalytic hydrothermal conversion of both the model compound and the residue.Increased metal dispersion and synergistic effects of two metals played indispensable roles in such catalytic system.Results showed that under the test conditions specified in the article,the catalyst had the best catalytic performance when the mass ratio of molybdenum to iron was 1.5.

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy electrode for hydrogen evolution reaction （HER）. The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 30% KOH solution containing 10% potassium sodium tartrate at 70℃ for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range （about 50 nm）, a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interruption shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.

Kinetics of catalytically activated duplication in aggregation growth

We propose a catalytically activated duplication model to mimic the coagulation and duplication of the DNA polymer system under the catalysis of the primer RNA. In the model, two aggregates of the same species can coagulate themselves and a DNA aggregate of any size can yield a new monomer or double itself with the help of RNA aggregates. By employing the mean-field rate equation approach we analytically investigate the evolution behaviour of the system. For the system with catalysis-driven monomer duplications, the aggregate size distribution of DNA polymers αk（t） always follows a power law in size in the long-time limit, and it decreases with time or approaches a time-independent steady-state form in the case of the duplication rate independent of the size of the mother aggregates, while it increases with time increasing in the case of the duplication rate proportional to the size of the mother aggregates. For the system with complete catalysis-driven duplications, the aggregate size distribution αk（t） approaches a generalized or modified scaling form.

Unraveling the catalytically active phase of carbon dioxide hydrogenation to methanol on Zn/Cu alloy: Single atom versus small cluster

Methanol synthesis from CO_(2)hydrogenation catalyzed by Zn/Cu alloy has been widely studied,but there is still debate on its catalytic active phase and whether the Zn can be oxidized during the reaction process.What is more,as Zn atoms could locate on Zn/Cu alloy surface in forms of both single atom and cluster,how Zn surface distribution affects catalytic activity is still not clear.In this work,we performed a systematic theoretical study to compare the mechanistic natures and catalytic pathways between Zn single atom and small cluster on catalyst surface,where the surface oxidation was shown to play the critical role.Before surface oxidation,the Zn single atom/Cu is more active than the Zn small cluster/Cu,but its surface oxidation is difficult to take place.Instead,after the easy surface oxidation by CO_(2)decomposition,the oxidized Zn small cluster/Cu becomes much more active,which even exceeds the hardlyoxidized Zn single atom/Cu to become the active phase.Further analyses show this dramatic promotion of surface oxidation can be ascribed to the following factors:i)The O from surface oxidation could preferably occupy the strongest binding sites on the center of Zn cluster.That makes the O intermediates bind at the Zn/Cu interface,preventing their too tight binding for further hydrogenation;ii)The higher positive charge and work function on the oxidized surface could also promote the hydrogenation of O intermediates.This work provided one more example that under certain condition,the metal cluster can be more active than the single atom in heterogeneous catalysis.

Catalytic aquathermolysis of Shengli heavy crude oil with an amphiphilic cobalt catalyst

An interfacially active cobalt complex,cobalt dodecylbenzenesulfonate,was synthesized.Elemental analysis,atomic absorption spectroscopy,Fourier transform infrared spectroscopy（FT-IR）,thermogravimetric analysis,and surface/interfacial tension determination were performed to investigate the properties of the catalyst.Results showed that the synthesized catalyst showed active interfacial behavior,decreasing the surface tension and interfacial tension between heavy oil and liquid phase to below 30 and 1.5 mN/m,respectively.The catalyst was not thermally degraded at a temperature of 400 ℃,indicating its high thermal stability.Catalytic performance of the catalyst was evaluated by carrying out aquathermolysis.The viscosity determination showed that the viscosity of the heavy oil decreased by 38%.The average molecular weight,group compositions,and average molecular structure of various samples were analyzed using elemental analysis,FT-IR,electrospray ionization Fourier transform ion cyclotron resonance（ESI FT-ICR MS）,and ～1H nuclear magnetic resonance.Results indicated that the catalyst could attack the sulfur- and O_2-type heteroatomic compounds in asphaltene and resin,especially the compounds with aromatic structure,leading to a decrease in the molecular weight and then the reduction in the viscosity of heavy oil.Therefore,the synthesized catalyst might find an application in catalytic aquathermolysis of heavy oil,especially for the high-aromaticity heavy oil with high oxygen content.

The Synthesis of Neodymium Complexes with Polymers Containing Thiol and Sulphoxide and Their Catalytic Activities

Introduction Polymers containing thiol and sulphoxide which have active—SH and—SO groups respectively, have wide application to biological, pharmaceutical, industrial and other chemical field and—SH and—SO groups are easy to form complexes with metals, so they have aroused an increasing interest of many authors. A large number of functional resins and corresponding metal complexes have been synthesized.

Evolution behavior of catalytically activated replication-decline in a coagulation process

We propose a catalytically activated replication-decline model of three species, in which two aggregates of the same species can coagulate themselves, an A aggregate of any size can replicate itself with the help of B aggregates, and the decline of A aggregate occurs under the catalysis of C aggregates. By means of mean-field rate equations, we derive the asymptotic solutions of the aggregate size distribution ak（t） of species A, which is found to depend strongly on the competition among three mechanisms： the self-coagulation of species A, the replication of species A catalyzed by species B, and the decline of species A catalyzed by species C. When the self-coagulation of species A dominates the system, the aggregate size distribution a^（t） satisfies the conventional scaling form. When the catalyzed replication process dominates the system, ak（t） takes the generalized scaling form. When the catalyzed decline process dominates the system, ak（t） approaches the modified scaling form.

Synthesis of Catalytic Systems Based on Nanocomposites Containing Palladium and Hydroxycarbonates of Rare-Earth Elements

The purpose of this work is to synthesize the catalytic systems containing palladium nanoparticles and using hydroxycarbonates of yttrium and cerium as supports,and to test the catalytic activity of the obtained catalysts in the Suzuki cross-couping reaction.Nanocomposites Pd/Y(OH)CO 3 and Pd/Ce(OH)CO 3 were synthesized according to two methods:the first one-simultaneous production of nanoscale substrate and immobilization of palladium nanoparticles on its surface(nanocomposites 1),the second one-the prior synthesis of polyvinylpyrrolidone stabilized palladium nanoparticles followed by their immobilization on the nano sized substrate surface(nanocomposites 2).The reaction between phenylboronic acid and iodobenzene is chosen as a model one.The dependence of the catalytic activity of catalysts on the method of their synthesis was established.It was established that nanocomposites 2 exhibit higher catalytic activity in the selected reaction compared to the nanocomposites 1.The TOF values for the nanocomposites 1 are 6663～14617 h 1 when using the substrate Ce(OH)CO 3 and 13774～27084 h 1 when using the substrate Y(OH)CO 3,while the nanocomposites 2 reveal TOF = 87287 h 1 for the substrate Ce(OH)CO 3 and TOF = 97746 h 1 for the substrate Y(OH)CO 3 under other equal conditions.In addition,nanocomposites 2 "work" at room temperature giving a high yield of the desired product.It is noted that the support nanoparticles Y(OH)CO 3 and Ce(OH)CO 3 also exhibit catalytic activity.The yield of the final product of the reaction using them as catalysts is 55%(TOF = 11 and 8 h 1,respectively).Thus,the use of yttrium and cerium hydroxycarbonates as supports allows to decrease the palladium content in the nanocomposites to 0.01%～1% and,consequently,reduce the cost of the catalyst while maintaining its high catalytic activity.

Kinetics of catalytically activated aggregation-fragmentation process

We propose a catalytically activated aggregation-fragmentation model of three species, in which two clusters of species A can coagulate into a larger one under the catalysis of B clusters; otherwise, one cluster of species A will fragment into two smaller clusters under the catalysis of C clusters. By means of mean-field rate equations, we derive the asymptotic solutions of the cluster-mass distributions ak（t） of species A, which is found to depend strongly on the competition between the catalyzed aggregation process and the catalyzed fragmentation process. When the catalyzed aggregation process dominates the system, the cluster-mass distribution ak（t） satisfies the conventional scaling form. When the catalyzed fragmentation process dominates the system, the scaling description of ak （t） breaks down completely and the monodisperse initial condition of species A would not be changed in the long-time limit. In the marginal case when the effects of catalyzed aggregation and catalyzed fragmentation counteract each other, ak（t） takes the modified scaling form and the system can eventually evolve to a steady state.