catalysis

摘要： The industrial manufacture of ammonia(NH_(3))using Fe-based catalyst works under rigorous conditions.For the goal of carbon-neutrality,it is highly desired to develop advanced catalyst for NH_(3)synthesis at mild conditions to reduce energy consumption and CO_(2)emissions.However,the main challenge of NH_(3)synthesis at mild conditions lies in the dissociation of steady N≡N triple bond.In this work,we report the design of subnanometer Ru clusters(0.8 nm)anchored on the hollow N-doped carbon spheres catalyst(Ru-SNCs),which effectively promotes the NH_(3)synthesis at mild conditions via an associative route.The NH_(3)synthesis rate over Ru-SNCs(0.49%(mass)Ru)reaches up to 11.7 mmol NH_(3)·(g cat)^(-1)·h^(-1) at 400°C and 3 MPa,which is superior to that of 8.3 mmol NH_(3)·(g cat)^(-1)·h^(-1) over Ru nanoparticle catalyst(1.20%(mass)Ru).Various characterizations show that the N_(2)H_(4)species are the main intermediates for NH_(3)synthesis on Ru-SNCs catalyst.It demonstrates that Ru-SNCs catalyst can follow an associative route for N_(2)activation,which circumvents the direct dissociation of N_(2)and results in highly efficient NH_(3)synthesis at mild conditions.

摘要： Development of renewable fuels,such as hydrogen,liquid ammonia,is of great significance for relieving the pressure of anthropogenic CO_(2)emissions and depletion of traditional fossil energy sources.For the past two decades,heterogeneous catalysis has received increased attention as an efficient route for the production of renewable fuels.Typical heterogeneous catalytic reactions include photocatalysis,electrocatalysis,photoelectrocatalysis,thermalcatalysis,photothermalcatalysis as well as some emerging catalytic pathways,e.g.piezocatalysis.Each catalytic reaction has its own advantages.For instance,electrocatalysis has the characteristic of high efficiency,photocatalysis is featured by the sustainability and low cost,thermalcatalysis generally shows a high practicability and scalability for industrialization,and coupled‐catalysis can integrate the merits of diversified catalytic reactions,achieving a more efficient catalytic performance for production of renewable fuels.Developing new catalytic reactions is anticipated to enrich the selection of possible catalytic system,and to advance the understanding of heterogeneous catalytic mechanism.

摘要： Rational design of Zn-containing HZSM-5 zeolite(Zn/HZSM-5)with high reactivity and excellent aromatization performance for olefin aromatization is crucially desired.We develop a new and uncomplicated method to synthesize Zn/HZSM-5(IMX/Z5)with superior aromatization performance in the paper.Compared to incipient wetness impregnation(IMP/Z5)and mechanical mixing(MIX/Z5),the asprepared IMX/Z5 presents a higher amount of surface ZnOH^(+)species(2.87%)while keeping identical bulk zinc content.As a result,more surface ZnOH^(+)favor both the aromatization of 1-hexene and cyclohexane dehydrogenation.For the two olefin aromatization pathways(hydrogen transfer and dehydrogenation),it is the first time found both the hydrogen transfer ability and the dehydrogenation ability increase linearly with the amount of surface ZnOH^(+)species while keeping identical bulk zinc content.We believe that the linear relationships are essential to design next generation olefin aromatization catalysts.

摘要： A series of Zn_(x)Ni_(y)CrO_(m±δ)catalysts were synthesized via a typical co-precipitation method,in which Zn-Cr layered double hydroxides(LDHs)were found and Ni-Zn intermetallic compound(IMC)was formed after reduction in hydrogen.During auto-thermal reforming(ATR)of acetic acid(HAc),the Ni-Zn IMC was transformed into Ni/(amorphous-ZnO)-ZnCr_(2)O_(4) species with uniformed distribution and appropriate interaction within these Ni-Zn-Cr-O species;besides,the adsorbed oxygen promoted the activation and transfer of oxygen species;therefore,deactivation by oxidation,sintering and coking was inhibited.And the optimized Zn_(2.37)Ni_(0.63)CrO_(4.5±δ)catalyst presented high activity and stability in a 45-h ATR test with HAc conversion near 100%and hydrogen yield at 2.7 mol-H_(2)/mol-HAc,showing potential for hydrogen production via ATR of HAc.

摘要： Ultra-deep desulfurization of transformer oil is of great demand among power industry.In this work,the effective and deep removal of various types of organosulfurs,including mercaptan,sulfide and disulfide via catalytic adsorptive desulfurization(CADS)using bifunctional Ti-based adsorbent is reported.Compared to adsorptive desulfurization(ADS),dramatically improvement of the organosulfur uptakes were achieved under CADS process.The equilibrium adsorption capacity at 5 μg∙g^(-1) S reached up to 15.7,33.4,11.6 and 11.9 mg∙g^(-1) for propyl mercaptan(n-PM),dimethyl sulfide(DMS),di-t-butyl disulfide(DTBDS)and dibenzyl disulfide(DBDS),which was 262,477,97 and 128 times to that of ADS process,respectively,and was the highest among the reported desulfurization adsorbents.Moreover,it achieved superior breakthrough capacity of 2050,530 and 210 ml F·(g A)^(-1) at the breakthrough S concentration of 1 μg∙g^(-1) of the commercial transformer oil S containing 10,50 and 150 μg∙g^(-1),respectively.The effectiveness of CADS is associated to the transformation of sulfur species to higher polar sulfonic species with the assistance of mild oxidant,which can be readily captured by silanol groups on SiO2 through Hbonding interaction.The excellent recyclability of the adsorbent can be realized through solvent washing or oxidative air treatment.This work provides an effective and economic approach for the elimination of trace amount of mercaptan,sulfide and disulfide from transformer oil.

摘要： With the world’s fossil fuels being finite in nature,an increasing interest focuses on the application of alternative renewable resources such as biomass.Biomass-derived platform chemicals with abundant functional groups have the potential to replace bulk chemicals for the production of value-added chemicals,fuels,and materials.The upgrading of these platform chemicals relies on the development of efficient catalytic systems.Hydrotalcite,with its wide compositional variety,tuneable anion-exchange capacity,and controlled acidity/basicity sites demonstrates great potential in the catalytic upgrading of biomass and the derived platform chemicals.The past decade has witnessed the emergence of research achievements on the development of efficient and robust hydrotalcite-derived metal catalysts and their applications in the upgrading of biomass or the derived platform chemicals.In this review,we aim to summarize the recent advances on the catalytic upgrading of biomass-derived platform chemicals(e.g.,furfural,5-hydroxymethylfurfural,levulinic acid,and glycerol)via hydrotalcitederived metal catalysts.We also observed that the crucial role of using hydrotalcite-derived catalysts relies on their strong metal–support interactions.As a result,a section focusing on the discussion of the metal–support interactions of hydrotalcitederived catalysts was provided.

摘要： Novel graphene-supported FeOOH nanodots(FeOOH NDs@G)were successfully prepared by a facile hydrothermal method and doped into MgH_(2)through mechanical ball-milling.MgH_(2)with 10wt%FeOOH NDs@G began to release hydrogen at 229.8°C,which is106.8°C lower than that of pure MgH_(2).The MgH_(2)-10wt%FeOOH NDs@G composite could reversibly absorb 6.0wt%hydrogen at 200°C under a 3.2 MPa hydrogen pressure within 60 min.With the addition of FeOOH NDs@G,the dehydrogenation and hydrogenation activation energy of MgH_(2)was decreased to 125.03 and 58.20 kJ·mol^(-1)(156.05 and 82.80 kJ·mol^(-1)for pure MgH_(2)),respectively.Furthermore,the hydrogen capacity of the FeOOH NDs@G composite retained 98.5%of the initial capacity after 20 cycles,showing good cyclic stability.The catalytic action of FeOOH NDs@G towards MgH_(2)could be attributed to the synergistic effect between graphene nanosheets and in-situ formed Fe,which prevented the aggregation of Mg/MgH2 particles and accelerated the hydrogen diffusion during cycling,thus enabling the Mg H_(2)-10wt%FeOOH NDs@G composite to exhibit excellent hydrogen storage performance.

摘要： Mesoporous transition metal oxide catalysts are well-used in the elimination of volatile organic compounds.In this study,we developed an efficient method for the preparation of mesoporous-Mn_(3)O_(4)(mMn_(3)O_(4))without the use of templates or surfactants.In this method,KCl protects oxygen defects on the surface of fresh Mn_(3)O_(4) crystallites.m-Mn_(3)O_(4) shows higher ameliorative catalytic activity than bulk-Mn_(3)O_(4)(b-Mn_(3)O_(4)) and calcined-Mn_(3)O_(4)(c-Mn_(3)O_(4)),achieving toluene catalytic oxidation of T_(10) and T_(90)(the temperature at a conversion rate of about 10%and 90%)at 191°Cand 230°C,respectively(WHSV=40,000 ml·g^(-1)·h^(-1)).Based on various characterizations,the prepared m-Mn_(3)O_(4)has large specific surface area and abundant oxygen defects,and thus can provide more surface active sites,which give it superior toluene combustion activity.

摘要： The bioleaching of chalcopyrite is low cost and environmentally friendly,but the leaching rate is low.To explore the mechanism of chalcopyrite bioleaching and improve its leaching rate,the effect and mechanism of manganese ions(Mn^(2+))and visible light on chalcopyrite mediated by Acidithiobacillus ferrooxidans(A.ferrooxidans)were discussed.Bioleaching experiments showed that when both Mn^(2+)and visible light were present,the copper extraction was 14.38%higher than that of the control system(without Mn^(2+)and visible light).Moreover,visible light and Mn^(2+)promoted the growth of A.ferrooxidans.Scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS)analysis revealed that Mn^(2+)promoted the formation of extracellular polymeric substance(EPS)on the surface of chalcopyrite,changed the morphology of A.ferrooxidans,enhanced the adsorption of bacteria on chalcopyrite surface with light illumination,and thus promoted the bioleaching of chalcopyrite.UV–vis absorbance spectra indicated that Mn^(2+)promoted the response of chalcopyrite to visible light and enhanced the catalytic effect of visible light on chalcopyrite bioleaching.Based on X-ray photoelectron spectroscopy(XPS),the relevant sulfur speciation of chalcopyrite before and after bioleaching were analyzed and the results revealed that visible light and Mn^(2+)promoted chalcopyrite bioleaching by reducing the formation of passivation layer(S_(n)^(2-)/S0).Investigation into electrochemical results further indicated that Mn^(2+)and visible light improved the electrochemical activity of chalcopyrite,thus increasing the bioleaching rate.

摘要： Ir is recognized as efficient catalyst for hydrogen evolution reaction(HER).The high price,however,has hindered its application in the production of hydrogen.In this work,we prepared the self-supported FeIr alloy nanoparticles,taking advantage of solid-state synthesis method.The as-prepared FeIr alloy possesses a novel morphology of pollen,which is consist of smaller FeIr nanoparticles.DFT calculations reveal that the change of the free Gibbs for Ir is negative after the adsorption of active H,while it is positive for the case of Fe.Thus,the alloying of Fe and Ir not only effectively reduces the cost,but also can achieve more adequate adsorption of active H species.Benefitting from this,the as-prepared FeIr alloy nanoparticle exhibits superior HER performance with an overpotential of 19 m V at a current density of 10 m V/cm^(2)and a Tafel slope of 32 m V/dec,when tested in 0.5 M H_(2)SO_(4),better than pure Ir and Pt/C.This work paves the way to the exploration of efficient alloy electrocatalysts for HER.

摘要： Membrane catalytic (MC) technology is introduced to improve the removal of elemental mercury(Hg0) from flue gas at lower temperature. The MC technology integrated membrane catalysis and Deaconreaction. The MC technology employed MnOxas the main catalytic components and doped with transitionmetals of Mo and Ru. The removal efficiencies of Hg0and the influence of the concentration of SO2, NO andO2on the removal of Hg0in the MC were studied and compared with traditional catalytic oxidation (TCO)mode. The results show that the MC technology can effectively overcome the shortcomings of the TCO modefor the removal of the trace level of Hg0in flue gas. The influence of NO and SO2on Hg0removal wereinsignificant even though 200 ppmv NO and 1000 ppmv SO2used. The results also show that the activities ofthe Mn catalyst, including retainability for oxidants and yield of Cl2derived from Deacon reaction, weresignificantly enhanced after doped with Mo and Ru. The Mn-Mo-Ru catalyst was found to effectively improvethe removal of Hg0from coal-fired flue gas. The removal efficiencies of Hg0reached 95%with Mn-Mo-Rucatalyst and 8 ppmv HCl at 423 K. Compared to the TCO mode, the demanded HCl for Hg0removal could beremarkably reduced. Results obtained warrant further development of this technique as a means of mercurypollution control.