Honeycomb-shaped PtSnNa/γ-Al2O3/cordierite monolithic catalyst with improved stability and selectivity for propane dehydrogenation

A novel honeycomb-shaped PtSnNa/γ-Al₂O₃/cordierite monolithic catalyst was developed. It was found that, the unique structure of the material led to the improved catalyst performances versus the conventional granule catalyst.     

Active carbon supported S-promoted Bi catalysts for acetylene hydrochlorination reaction

We synthesized a S doped Bi/AC catalyst for acetylene hydrochlorination. The addition of H₂SO₄ changes the structure of the Bi atoms in the catalyst, resulting in the improvement of the specific surface areas and catalytic efficiency of the Bi-based catalyst under reaction conditions.     

Application of Li2SiO3 as a heterogeneous catalyst in the production of biodiesel from soybean oil

Biodiesel was synthesized from soybean oil by transesterification over Li₂SiO₃ catalyst.The Li₂SiO₃ can be used for biodiesel production directly without further drying or thermal pretreatment,no obvious difference in the FAME conversion（92.4-96.7%） between the air-exposed catalyst（24-72 h） and the fresh one（94.2%）.This leads to important benefits when considering industrial applications of Li₂SiO₃ as a solid catalyst for storing and handling catalyst without taking special actions.     

Regeneration of C4H10 dry reforming catalyst by nonthermal plasma

Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons.An effort was made to regenerate the catalyst（Ni/7-alumina） by oxidation methods.Two approaches were carried out for the regeneration of the deactivated catalyst.The first one involves the plasma treatment of the deactivated catalyst in the presence of dry air over a temperature range of 300～500℃,while the second one only the thermal treatment in the same temperature range.The performance of the regenerated catalyst was evaluated in terms of C₄H₁₀ and CO₂ conversions and the physicochemical characteristics were examined using a surface area analyzer,an elemental analyzer,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.It was observed that the carbon deposit （coke） on the catalyst was about 9.89 wt%after reforming C₄H₁₀ for 5 h at 540℃.The simple thermal treatment at 400℃reduced carbon content to 6.59 wt%whereas it was decreased to 3.25 wt%by the plasma and heat combination.The specific surface area was fully restored to the original state by the plasma-assisted regeneration at 500℃.As far as the catalytic activity is concerned,the fresh and regenerated catalysts exhibited similar C₄H₁₀ and CO₂ conversion efficiencies.     

Catalytic effect of lucunary heteropolyanion containing molybdenum and tungsten atoms on decolorization of direct blue 71

In this research,a lucunary Keggin structure,[PMo₂W₉O₃₉]^7- was selected as an efficient homogenous catalyst for degradation of an azo dye（direct blue 71） and a simple method was developed for degradation of DB71.The method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates,K₇[PMo₂W₉O₃₉]? 19H₂O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H₂O₂,pH and reaction time were investigated and optimized. Results show that K₇[PMo₂W₉O₃₉]? 19H₂O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H₂O₂ could lead to the disappearance approximately 65%of dye after 60 min.But degradation for the same experiment performed in the absence of catalyst or in the absence of H₂O₂ was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H₂O₂ and optimize conditions(0.6 g/L of K₇[PMo_2- W₉O₃₉H₉H₂O,0.08 mol/L hydrogen peroxide and room temperature).     

Highly active Pd containing EMT zeolite catalyst for indirect oxidative carbonylation of methanol to dimethyl carbonate

Palladium containing EMT zeolite catalyst(Pd/EMT) was prepared and used for the indirect oxidative carbonylation of methanol to dimethyl carbonate(DMC).The EMT zeolite was employed as a new catalyst support and compared with the conventional Pd containing FAU zeolite catalyst(Pd/FAU).The Pd/EMT in contrast to the Pd/FAU catalyst exhibited high intrinsic activity with the turnover frequency of 0.25 s^-1 vs.0.11 s^-1.The Pd/EMT catalyst showed high CO conversion of 82% and DMC selectivity of 79%,that maintained for at least 130 h,while the activity of the Pd/FAU catalyst rapidly deteriorated within 12 h.The enhanced interactions between Pd and EMT zeolite inhibited the sintering of palladium clusters and maintained the Pd2+ active sites in the Pd/EMT catalyst.The stabilization of the mono-dispersed Pd clusters within the EMT zeolite is paramount to the excellent performance of the catalyst for the indirect oxidative carbonylation of methanol to DMC.     

Tailoring synergetic catalytic interface of VPO/Ni2P to boost hydrogen evolution under alkaline conditions

Design of the catalyst for efficient water dissociation and hydrogen recombination is paramount in enhancement of the alkaline water electrolysis kinetics.Herein,we reported a delicate hierarchical(VO)₂ P₂O₇-Ni₂ P@NF(VPO-Ni₂ P@NF)hybrid catalyst that operated efficiently in alkaline media.The VPO and Ni₂ P respectively act as the water dissociation promoter and the hydrogen recombination center,which synergistically propel water adsorption/dissociation and H intermediates recombination.The resulting synergistic interfaces between VPO and Ni₂ P are verified to afford the catalyst an outstanding performance for hydrogen evolution reaction in alkaline media with an overpotential of 154 mV at 10 mA cm^-2,Tafel slope of 65 mV dec^-1,and remarkable durability.Furthermore,the catalyst presents the potential for overall water splitting.This work may shed fresh light on the high-performance electrocatalyst design and the application of VPO on water electrolysis.     

Synergetic effect of FeVO4 and α-Fe2O3 in Fe-V-O catalysts for liquid phase oxidation of toluene to benzaldehyde

Synergistic effect of FeVO₄ withα-Fe₂O₃ was found in Fe-V-O catalyst,which was responsible for the high apparent formation rate（A.F.R.） of benzaldehyde in liquid phase oxidation of toluene by hydrogen peroxide.The synergistic effect might create VO_πspecies as active sites;moreover,it improved the reducibility and the reactivity of Fe-V-O catalyst.In order to gain the high A.F.R. of benzaldehyde,the catalyst should have the moderate reducibihty.     

Preparation of polypropylene/clay nanocomposites by <Emphasis Type="Italic">in situ</Emphasis> polymerization with TiCl<Subscript>4</Subscript>/MgCl<Subscript>2</Subscript>/clay compound catalyst

TiCl₄/MgCl₂/clay compound catalyst was prepared by chemical reaction.Exfoliated polypropylene（PP）/clay nanocomposites were synthesized by in situ polymerization with this compound catalyst.Effects of polymerization temperature,polymerization time,propylene pressure,solvent consumption and pre-treat time of catalyst on catalyst activity and catalytic stereospecificity were studied.Under optimal conditions,activity of the nano-compound catalyst is about 88.3 kg/（mol Ti·h）.Isotacticity of PP obtained in the nanocomposites is in the range of 89%-99%,and its melting temperature is about 159℃.The weight-average molecular weight of PP can reach 6.7×10⁵ - 7.8×10⁵,and the molecular weight distribution is between 7.7 and 7.9.     

Graphene-nickel nitride hybrids supporting palladium nanoparticles for enhanced ethanol electrooxidation

Electrocatalysts for ethanol oxidation reaction(EOR)are generally limited by their poor durability because of the catalyst poisoning induced by the reaction intermediate carbon monoxide(CO).Therefore,the rapid oxidation removal of CO intermediates is crucial to the durability of EOR-based catalysts.Herein,in order to effectively avoiding the catalyst CO poisoning and improve the durability,the graphene-nickel nitride hybrids(AG-Ni₃N)were designed for supporting palladium nanoparticles(Pd/AG-Ni₃N)and then used for ethanol electrooxidation.The density functional theory(DFT)calculations demonstrated the introduction of AG-Ni₃N depresses the CO absorption and simultaneously promotes the adsorption of OH species for CO oxidation removal.The fabricated Pd/AG-Ni₃N catalyst distinctively exhibits excellent electroactivity with the mass catalytic activity of 3499.5 m A mg^-1 on EOR in alkaline media,which is around 5.24 times higher than Pd/C(commercial catalyst).Notably,the Pd/AG-Ni₃N hybrids display excellent stability and durability after chronoamperometric measurements with a total operation time of 150,000 s.     

A zirconium modified Co/SiO2 Fischer-Tropsch catalyst prepared by dielectric-barrier discharge plasma

Co/SiO₂ and zirconium promoted Co/Zr/SiO₂ catalysts were prepared using dielectric-barrier discharge（DBD） plasma instead of the conventional thermal calcination method.Fischer-Tropsch Synthesis（FTS） performances of the catalyst were evaluated in a fixed bed reactor.The results indicated that the catalyst treated by DBD plasma shows the higher FTS activity and yield of heavy hydrocarbons as compared with that treated by the conventional thermal calcination method.Increase in CO conversion was unnoticeable on the Co/SiO₂ catalyst,but significant on the Co/Zr/SiO₂ catalyst,both prepared by DBD plasma.On the other hand,heavy hydrocarbon selectivity and chain growth probability （a value） were enhanced on all the catalysts prepared by the DBD plasma.In order to study the effect of the DBD plasma treatment on the FTS performance,the catalysts were characterized by N₂-physisorption,H2-temperature programed reduction（H₂-TPR）,H₂-temperature-programmed desorption（H₂-TPD） and oxygen titration,transmission electron microscope（TEM） and X-ray diffraction（XRD）.It was proved that,compared with the traditional calcination method,DBD plasma not only could shorten the precursor decomposition time,but also could achieve better cobalt dispersion,smaller Co₃O₄ cluster size and more uniform cobalt distribution.However,cobalt reducibility was hindered to some extent in the Co/SiO₂ catalyst prepared by DBD plasma,while the zirconium additive prevented significantly the decrease in cobalt reducibility and increased cobalt dispersion as well as the FTS performance.     

Magnetic graphene nanocomposite as an efficient catalyst for hydrogenation of nitroarenes

Graphene-Fe₃O₄ nanocomposite（G-Fe₃O₄） was synthesized by a chemical co-precipitation method which was used as an efficient catalyst for the reduction of nitroarenes with hydrazine hydrate.The method has been applied to a broad range of compounds with different properties and the yields were in the range of 75%-92%.The G-Fe₃O₄ catalyst can be readily recovered and reused 5 times without significant loss of the catalytic activity.     

Synergistic catalysis of isolated Fe~(3+) and Fe_2O_3 on FeO_x/HZSM-5 catalysts for Friedel-Crafts benzylation of benzene

FeO_x/HZSM-5 catalyst with 8 wt.%Fe-loading（8-FeZ） exhibited significantly higher reactivity in the benzylation of benzene with benzyl chloride than FeO_x/HZSM-5 catalyst with 2.5 wt.%Fe-loading（2.5-FeZ） because the synergistic catalysis between isolated Fe³⁺ and superfine Fe₂O₃ occurred on 8-FeZ in the reaction.     

NiSe2-CoSe2 with a Hybrid Nanorods and Nanoparticles Structure for Efficient Oxygen Evolution Reaction

Hetero-structure induced high performance catalyst for oxygen evolution reaction(OER)in the water splitting reaction has received increased attention.Herein,we demonstrated a novel catalyst system of NiSe₂-CoSe₂ consisting of nanorods and nanoparticles for the efficient OER in the alkaline electrolyte.This catalyst system can be easily fabricated via a low-temperature selenization of the solvothermal synthesized NiCo(OH)x precursor and the unique morphology of hybrid nanorods and nanoparticles was found by the electron microscopy analysis.The high valence state of the metal species was indicated by X-ray photoelectron spectroscopy study and a strong electronic effect was found in the NiSe₂-CoSe₂ catalyst system compared to their counterparts.As a result,NiSe₂-CoSe₂ exhibited high catalytic performance with a low overpotential of 250 mV to reach 10 mA·cm^-2 for OER in the alkaline solution.Furthermore,high catalytic stability and catalytic kinetics were also observed.The superior performance can be attributed to the high valence states of Ni and Co and their strong synergetic coupling effect between the nanorods and nanoparticles,which could accelerate the charge transfer and offer abundant electrocatalytic active sites.The current work offers an efficient hetero-structure catalyst system for OER,and the results are helpful for the catalysis understanding.     

Epoxy ether cleaving reactions catalyzed by supporting Lewis acidic ionic liquid

Lewis acidic ionic liquids were used to catalyze the reaction of epoxypropane with POCl₃.Considering the lower cost and catalytic activities,we concluded that[Et₃NH]Cl/AlCl₃ was the most attractive ionic liquid from an economical point of view.But it would be easily inactivated because of sensitive to water and air.Moreover,it could not be reused easily because of difficulty recovery in the reaction.However,supporting[Et₃NH]Cl/AlCl₃ catalyst could resolve above problems.Supporting[Et₃NH]Cl/ AlCl₃ catalyst could be separated by filter easily and reused 5 times in 98%yield.Furthermore,the catalyst was applicable to other epoxy ether cleaving reactions.     

Insight into the hydrogen oxidation electrocatalytic performance enhancement on Ni via oxophilic regulation of MoO_2

Exploring platinum-group-metal(PGM)free electrocatalysts for hydrogen oxidation reaction(HOR)in alkaline media is essential to the progress of anion exchange membrane fuel cells(AEMFCs).In this work,a Ni/MoO₂ heterostructure catalyst with comparable HOR activity in alkaline electrolyte with PGM catalyst was prepared by a simple hydrothermal-reduction method.Remarkably,the Ni/MoO₂ presents a mass kinetic current density of 38.5 mA mgNi^-1 at the overpotential of 50 mV,which is higher than that of the best PGM free HOR catalyst reported by far.Moreover,the HOR performance of Ni/MoO₂ under 100 ppm CO shows negligible fading,together with the superior durability,render it significant potential for application in AEMFCs.A particular mechanistic study indicates that the excellent HOR performance is ascribed to the accelerated Volmer step by the incorporation of MoO₂.The function of MoO₂ was further confirmed by CO striping experiment on Pt/C-MoO₂ that MoO₂ can facilitated OH adsorption thus accelerate the HOR process.On account of the high performance and low cost,the Ni/MoO₂ electrocatalyst encourages the establishment of high performance PGM free catalyst and shows significant potential for application in AEMFCs.     

Optimization and statistical analysis of Au-ZnO/Al2O3 catalyst for CO oxidation

In our former work[Catal.Today 174（2011） 127],12 heterogeneous catalysts were screened for CO oxidation,and Au-ZnO/Al₂O₃ was chosen and optimized in terms of weight loadings of Au and ZnO.The present study follows on to consider the impact of process parameters （catalyst preparation and reaction conditions）,in conjunction with catalyst composition（weight loadings of Au and ZnO,and the total weight of the catalyst）,as the optimization of the process parameters simultaneously optimized the catalyst composition.The optimization target is the reactivity of this important reaction.These factors were first optimized using response surface methodology（RSM） with 25 experiments,to obtain the optimum:100 mg of 1.0%Au-4.1%ZnO/Al₂O₃ catalyst with 220℃calcination and 100℃reduction.After optimization,the main effects and interactions of these five factors were studied using statistical sensitivity analysis（SA）.Certain observations from S A were verified by reaction mechanism,reactivity test and/or characterization techniques,while others need further investigation.     

CeO2 Particles Anchored to Ni2P Nanoplate for Efficient Photo-catalytic Hydrogen Evolution

Photocatalytic hydrogen evolution can convert intermittent and dispersive solar energy into hydrogen with high energy density,which is expected to fundamentally solve the problems of environmental pollution and energy shortages.In this experiment,the performance of the catalyst is modified by introducing cocatalyst and morphology control.Ni(OH)2 nanoflowers are used as substrates to derive nanoplate stack Ni₂P by high-temperature phosphating method,and a great many of CeO₂ nanoparticles are anchored in the Ni₂P.This unique 3D/0D combination effectively inhibits the agglomeration of CeO₂ nanoparticles and shortens the electron transfer path.Secondly,the introduction of metal-like performance of Ni₂P broadens the light absorption range of the catalyst and reduces the overpotential of the catalyst,which is a key factor in enhancing the catalytic activity.The design ideas of this experiment have reference significance for the design of efficient and environmentally friendly photocatalysts.     

Recyclable Fenton-like catalyst based on zeolite Y supported ultrafine,highly-dispersed Fe2O3 nanoparticles for removal of organics under mild conditions

The active Fenton-like catalyst, obtained by highly dispersed Fe₂O₃ nanoparticles in size of 5 nm on the surface of zeolite Y, shows the excellent degradation efficiency to phenol higher than 90% under the mild conditions of room temperature and neutral solution, and the catalyst can be easily recovered with stable catalytic activity for 8 cycles.     

An efficient single atom catalysts Os/P3C sheet for ammonia borane dehydrogenation

Ammonia borane （NH₃BH₃, AB） has been considered to be a promising chemical hydrogen storage material. Based on density functional theory, a series of transition metal atoms supported P₃C （P₃C＿O） sheet is systematically investigated to screen out the most promising catalyst for dehydrogenation of AB. The results indicate that the Os/P₃C and Os/P₃C＿O could be an efficient single atom catalyst （SACs） and the stepwise reaction pathway...