Highly Dispersed Pd Nanoparticles Supported on Zr-Doped MgAl Mixed Metal Oxides for 2-Ethylanthraquinone Hydrogenation

In this study,Pd-Mg(Al)-LDH/γ-Al_2O_3 and Pd-Mg(Al)Zr-LDH/γ-Al_2O_3 precursors were synthesized by impregnating Na_2PdCl_4 on Mg(Al)-LDH/γ-Al_2O_3 and Mg(Al)Zr-LDH/γ-Al_2O_3,and then the precursors were calcinated and reduced to obtain Pd-Mg(Al)-MMO/γ-Al_2O_3 and Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 catalysts.Compared with Pd/γ-Al_2O_3 catalyst,the hydrogenation efficiency of Pd-Mg(Al)-MMO/γ-Al_2O_3 and Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 increased by 15.7%and 24.0%,respectively.Moreover,the stability of Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 catalyst was also higher than that of Pd/γ-Al_2O_3.After four runs,the hydrogenation efficiency of Pd/γ-Al_2O_3 decreased from 12.1 to 10.0 g/L,while that of Pd-Mg(Al)Zr-MMO/γ-Al_2O_3 decreased from 15.0 to 14.3 g/L.The active aquinones selectivities of all catalysts were almost 99%.The structures of the catalysts were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),N_2 adsorption-desorption,inductively coupled plasma-atomic emission spectrometry (ICP-AES),CO chemisorption analysis,transmission electron microscopy (TEM),temperature-programmed reduction with hydrogen (H_2-TPR),and X-ray photoelectron spectroscopy(XPS).The results indicate that the improved catalytic performance is attributed to the stronger interaction between Pd and Mg(Al)Zr-MMO/γ-Al_2O_3,smaller Pd particle size and higher Pd dispersion.This work develops an effective method to synthesize highly dispersed Pd nanoparticles based on the layered double hydroxides (LDHs) precursor.     

Hydrogenation of ortho-nitrochlorobenzene on activated carbon supported platinum catalysts

INTRODUCTION 2,2′-dichlorohydrazobenzene (DHB) is a com-mercially important intermediate, and is convention-ally manufactured by zinc reduction of or-tho-nitrochlorobenzene (Xu, 1996). The major dis-advantage of this process is the generation of largeamounts of sludge in reduction. A single step catalytichydrogenation of ortho-nitrochlorobenzene to DHBusing supported noble metal catalyst in the presenceof aqueous sodium hydroxide medium becomes moreimportant, because it is enviro…     

Preparation of Cu/ZnO/Al2O3 catalysts in a solvent-free routine for CO hydrogenation

The synthesis of methanol and dimethyl ether (DME) from CO hydrogenation has been investigated on Cu-based catalysts. A series of Cu/ZnO/Al₂O₃ catalysts were prepared using a solvent-free routine which involved a direct blend of copper/zinc/aluminum salts and citric acid, followed by calcination at 450 °C. The calcination processes were monitored using thermogravimetry differential scanning calorimetry (TG-DSC). Catalysts were further characterized using N₂ adsorption, scanning electronic microscopy (SEM), X-ray diffraction (XRD), N₂O oxidation followed by H₂ titration, and temperature-programmed reduction with H₂ (H₂-TPR). The reduction processes were also monitored with in-situ XRD. The physicochemical properties of catalysts depended strongly on the types of precursor salts, and catalysts prepared using Al acetate and Cu nitrate as starting materials had a larger surface area, larger exposed metallic copper surface area, and lower reduction temperature. The CO hydrogenation performances of these catalysts were compared and discussed in terms of their structures. Catalysts prepared with copper nitrate, zinc and aluminum acetates exhibited the highest catalytic activity.     

Ionic Liquid-Complex Pd/C System as Catalyst for Copolymerization of CO and Styrene简

The copolymerization of CO and styrene catalyzed by Pd/C toward the formation of polyketones(PK)was studied in the N-valeronitrile-N'-methylimidazolium hexafluorophosphate([C4CNmim]+PF-6) medium. The synthesized PK was characterized by Fourier transform infrared(FTIR), elemental analysis, 13C-nuclear magnetic resonance(13C-NMR), differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and gel permeation chromatography(GPC). The supported ionic liquid film on the surface of Pd/C catalyst can prevent the products from covering the hole of active carbon due to its chemical stability and weak coordination ability with metal ions, and thus efficiently improve the catalytic activity. The effects of different amounts of ionic liquid on the catalytic activity and reusability of the catalyst and the molecular weight of PK were discussed. When the usage of ionic liquid is 10wt%(0.1 g ionic liquid / 1 g active carbon carrier) and the theoretical content of Pd2+ is 5wt%(0.05 g Pd2+/ 1 g active carbon carrier), the highest catalytic activity 2 963.64 gSTCO/(gPd·h) is achieved with the molecular weight and polydispersity index of PK as Mn=9 684, Mw=13 452 and Mw /Mn=1.389.     

空心三元PdPtCu纳米材料的制备及其对乙醇氧化的电催化性能研究

采用诱导法制备空心三元PdPtCu纳米材料,利用透射电镜(TEM)、扫描电镜(SEM)和X射线衍射(XRD)对其形貌、组成和结构进行表征,并在碱性条件下测试其对乙醇氧化的电催化性能。结果表明,以氧化铜为诱导剂制备的三元PdPtCu纳米材料主要呈空心结构,且其形貌和组成可控;Pd₃Pt@Cu,PdPt@Cu和PdPt₃@Cu三种材料的质量电流密度分别为8 510 A·g^-1,9 270 A·g^-1和5 490 A·g^-1,无论是质量活性还是稳定性,均明显优于商业Pd/C和商业Pt/C催化剂。     

Optimization of Co-precipitation Condition for Preparing Molybdenum-Based Sulfur-Resistant Methanation Catalysts

In this study, the effects of ZrO_2 carrier precursors, MoO_3 loading, and washing treatment on the catalytic performance of Mo O_3/ZrO_2 toward sulfur-resistant methanation were investigated. All the catalysts were prepared by co-precipitation method and further characterized by N_2 adsorption–desorption, H_2-temperature-programmed reduction, X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The prepared MoO_3/ZrO_2 catalysts were tested in a continuous-flow pressurized fixed bed reactor for CO methanation. The results revealed that the carrier precursors, MoO_3 loading, and washing treatment affected not only the crystalline phase of Mo species but also the grain size of ZrO_2 carrier and consequently influenced the MoO_3/ZrO_2 activity toward sulfur-resistant methanation. The 25 wt% MoO_3/ZrO_2 catalyst prepared using Zr(NO_3) 4 ·5 H_2O as the precursor and treated by water washing displayed the best activity for sulfur-resistant methanation due to its greater number of octahedral Mo species and smaller ZrO_2 grain size.     

活性组分在载体表面的分散状态

许多催化剂的活性组分可在载体表面自发分散.XRD,LRS和XPS等技术可用于研究活性组分在载体表面的分散状态,并测得相应的分散阈值.结果表明,当活性组分含量低于其分散阈值时,它在载体表面呈单层但非密置单层分散,逾此阈值时出现晶相.自发分散效应可以称为自发单层分散原理,这一自发单层分散原理可用于解释和改进多相催化剂制备工艺条件、解决相关的表面结构问题.     

Preparation and characterization of mesoporous indium oxide

Indium oxide nanocrystals with mesoporous structure were successfully synthesized by using triblock copolymer as a template, and characterized by thermogravimetry-differential scanning calorimeter (TG-DSC), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and N₂ adsorption. A high EO/PO ratio is thought to be the key point to prepare mesoporous In₂O₃. The results show that the average pore diameter of the products is 6 nm, the BET surface area is 54.78 m²/g, and the adsorbing pore volume is 0.345 cm³/g. After comparing with normal indium oxide nanoparticles by BET test, mesoporous indium oxide demonstrates a large difference in adsorbing pore volume and average pore diameters from normal ones. Project supported by the Leading Academic Discipline Project of Shanghai Municipal Education Commission (Grant No.J50102)     

果胶@生物炭-Fe3O4的制备及其对Cu2+的吸附性能

以木屑为原料,高温热解制备生物炭。以聚乙烯醇为粘结剂,采用混合法将生物炭与果胶复合,并负载磁性,经烘干定型制备果胶包覆的磁性生物炭材料（果胶@生物炭-Fe₃O₄）。采用扫描电镜（SEM）、X射线衍射（XRD）及N₂吸附-脱附（BET）等方法对果胶@生物炭-Fe₃O₄进行表征,结合吸附实验分析其对Cu²⁺的吸附特性。结果表明,当生物炭、果胶、Fe₃O₄质量比为5：1：1,溶液pH值为6,吸附24 h,果胶@生物炭-Fe₃O₄对Cu²⁺吸附效果最好;二级动力学方程能较好地描述果胶@生物炭-Fe₃O₄对Cu²⁺的吸附过程,Freundlich模型能较好地拟合其吸附行为;SEM结果显示该材料具有不规则的孔隙结构;XRD分析显示纳米Fe₃O₄是其主要的晶体结构;BET测得其比表面积为25.654 m²·g^-1,平均孔径为20.18 nm。     

Dual bed catalyst system for oxidative dehydrogenation of mixed-butenes: a synergistic mechanism

Oxidative dehydrogenation (ODH) of mono and mixed-butenes to 1,3-butadiene (BD) was conducted using individual and dual bed catalyst systems, consisting of ZnFe₂O₄, Co₉Fe₃Bi₁Mo₁₂O₅₁ or both. The dual bed catalyst system gave improved catalytic performance. A mechanism based on synergy between the catalysts is proposed to explain the improved overall butene conversion. The proportion of the reactants differed between the catalyst beds in the dual bed system, making better use of the catalytic activity of the second bed. The existence of all butene isomers inhibited isomerization, leading to a higher proportion of ODH reactions and thus improved the conversion of butene and the yield of BD. The packing sequences and the volume ratio of the catalysts in the bed were optimized. The results indicated that the sequence with ZnFe₂O₄ on top and a catalyst packing ratio of between 4:6 and 6:4 led to better activity.     

Designing Pd-based supported bimetallic catalysts for environmental applications

Supported bimetallic nanoparticulate catalysts are an important class of heterogeneous catalysts for many reactions including selective oxidation, hydrogenation/hydrogenolysis, reforming, biomass conversion reactions, and many more. The activity, selectivity, and stability of these catalysts depend on their structural features including particle size, composition, and morphology. In this review, we present important structural features relevant to supported bimetallic catalysts focusing on Pd-based bimetallic systems and recently reported strategies to control them through different synthesis methodologies. Further, we focus on a few reactions that are relevant to environmental catalysis, i.e. CO oxidation, hydrocarbon oxidation, hydrodechlorination, and NO _x decomposition, where Pd-based catalysts are often used successfully. In spite of much progress in these areas, still there is a need for more advanced catalytic technologies to address the grand challenges like environmental remediation. Some of the recent advances in the design of bimetallic catalysts were made because of the combined efforts of material scientists, spectroscopists, microscopists, catalysis chemists, and engineers through state-of-the-art characterization methodologies, mechanistic investigations, and structure-activity correlations. This review is aimed at inspiring scientists to rationally design catalysts for a green and sustainable future.     

Effect of agarose content on microstructures and mechanical properties of porous silicon nitride ceramics produced by gelcasting

<正>Porous Si3N4 self-reinforce ceramics were prepared by gelcasting using agarose solutions. By changing the agarose content in the slurries, the porous silicon nitride ceramics with different porosities, α→β-Si3N4 phase transformation, and mechanical properties were obtained. When the agarose content changed from 0.2% to 0.8% (w/w, based on powder), the porosities increased from 10.3% to 21.4%, while the fracture strength decreased from 455 to 316 MPa and the fracture toughness decreased from 6.6 to 5.5 MPa·m1/2. Many fibrous β-Si3N4 grains grown from the internal wall of the round pores is the typical microstructure of the gelcasting porous silicon nitride ceramic. Both elongated β-Si3N4 grains and suitable interfacial bonding strength contributes to high fracture toughness by favoring crack deflection and bridging. The growth mechanisms of fibrous grains resulted from the synergy of solution-diffusion-reprecipitation and vapor-liquid-solid (VLS).     

Catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 in NO＋CO reaction

Using SnxTi1-xO2 as carriers, CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide (CuO) were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 were examined using a microreactor-gas chromatography (GC) NO CO reaction system and the methods of BET (Brun- auer-Emmett-Teller), TG-DTA (themogravimetric and differential thermal analysis), X-ray diffraction (XRD) and H2-temperature programmed reduction (TPR). The results showed that NO conversions of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT (Brunauer, Deming, Deming and Teller) system and a typical mesoporous sample. There were two CuO diffraction peaks (2θ 35.5° and 38.7°), and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks (α, β and γ) from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the γ peak was the reduction of crystal phase copper oxide. In addition, a fourth peak (δ) of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.     

Fe_3O_4/C/Pd复合材料的制备及催化Suzuki反应研究

通过实验制备出了Fe3O4、Fe3O4/C、Fe3O4/C/Pd纳米粒子,并将其应用于Suzuki偶联反应.以Fe3O4为载体通过溶剂热法将C包覆在Fe3O4上,再在得到的复合材料上包覆Pd得到Fe3O4/C/Pd催化剂.通过X-射线衍射(XRD)和透射电子显微镜(TEM)对产物进行表征,并对结果进行粒径形貌分析.实验结果表明,Suzuki反应在以DMF/H2O(V/V=1)为溶剂,Na2CO3为碱时,在反应温度为80℃下,反应5 h时催化剂的催化性能最佳.     

HNCO hydrolysis performance in urea-water solution thermohydrolysis process with and without catalysts

The thermolysis of urea-water solution and its product, HNCO hydrolysis is investigated in a dual-reactor system. For the thermal decomposition below about 1073 K, the main products are ammonia (NH3) and isocyanic acid (HNCO) whereas at higher temperatures the oxidation processes take effect and the products include a low concentration of nitric oxide (NO) and nitrous oxide (N2O). The gas HNCO is quite stable and a high yield of HNCO is observed. The ratio of NH3 to HNCO increases from approximately 1.2 to 1.7 with the temperature. The chemical analysis shows that H radical is in favor of HNCO hydrolysis by instigating the reaction HNCO+H·→·NH2+CO and high temperature has positive effect on H radical. The hydrolysis of HNCO over an alumina catalyst made using a sol-gel process (designated as γ-Al2O3) is investigated. The conversion of HNCO is high even at the high space velocities (6×105 h-1) and low temperatures (393–673 K) in the tests with catalysts, which enhances HNCO hydrolysis and raises the ratio of NH3 to HNCO to approximately 100. The pure γ-Al2O3 shows a better catalytic performance than CuO/γ-Al2O3. The addition of CuO not only reduces the surface area but also decreases the Lewis acid sites which are recognized to have a positive effect on the catalytic activity. The apparent activation energy of the hydrolysis reaction amounts to about 25 kJ/mol in 393–473 K while 13 kJ/mol over 473 K. The overall hydrolysis reaction rate on catalysts is mainly determined by external and internal mass-transfer limitations.     

Ultra-Thin Carbon-Doped Bi2WO6 Nanosheets for Enhanced Photocatalytic CO2 Reduction

The photocatalytic reduction of CO₂ is a promising strategy to generate chemical fuels. However, this reaction usually suffers from low photoactivity because of insufficient light absorption and rapid charge recombination. Defect engineering has become an effective approach to improve the photocatalytic activity. Herein, ultra-thin (~ 4.1 nm) carbon-doped Bi₂WO₆ nanosheets were prepared via hydrothermal treatment followed by calcination. The ultra-thin nanosheet structure of the catalyst not only provides more active sites but also shortens the diffusion distance of charge carriers, thereby suppressing charge recombination. Moreover, carbon doping could successfully extend the light absorption range of the catalyst and remarkably promote charge separation, thus inhibiting recombination. As a result, the as-prepared Bi₂WO₆ photocatalyst with ultra-thin nanosheet structure and carbon doping exhibits enhanced photocatalytic CO₂ reduction performance, which is twice that of pristine ultra-thin Bi₂WO₆ nanosheet. This study highlights the importance of defect engineering in photocatalytic energy conversion and provides new insights for fabricating efficient photocatalysts.

     

Performance Evaluation of Modified Black Clay as a Heterogeneous Fenton Catalyst on Decolorization of Azure B Dye: Kinetic Study and Cost Evaluation

Black clay(BC) was used as a catalyst for the decolorization of Azure B dye by Fenton process. BC was modified by acid, alkali, distilled water, and calcination to check their changes in characterization and efficiency on decolorization of Azure B. Among three modified catalysts, maximum decolorization was obtained by acid-modified BC(AMBC) catalyst due to the highest removal of impurities, comparatively. The characterization of AMBC was done by Fourier-transform infrared spectroscopy and X-ray diffraction spectroscopy which show the presence of metal ion. The BET surface area, pore volume, pore size, and density of AMBC were calculated to be 79.402 m~2/g, 0.0608 m~3/g, 0.00306 nm, and 16 g/cm~3, respectively. The highest decolorization of 97.59% was achieved only in 10 min using AMBC at optimized calcination of 100 °C and 3 h of aging. AMBC was considered as the main catalyst for optimizing the different process parameters. Optimized conditions were obtained: pH 2, 0.2 mL of H_2O_2, catalyst dose 0.3 g, room temperature(30 °C), and stirring speed 400 r/min. The catalyst has showed excellent stability and reusability. It could remove more than 85% of color even after four cycles of run and less than negligible leaching of iron. AMBC has good recycling ability among other modified catalysts. To check the selectivity of catalyst, different dyes such as Congo red and mixed dye(mixture of Azure B and Congo red) decolorization were studied. In the present work, kinetic study was also carried out and a three-stage decolorization process was found.     

MoO_3/TiO_2—SiO_2催化剂的阈值效应研究

采用气相流动吸附法制TiO_2/SiO_2复合载体,浸渍法担载一定量MoO_3。用XRD、LRS和TPR等技术考察了MoO_3在TiO_2/SiO_2表面的分散状态,中压固定床反应装置测定MoO_3/TiO_2—SiO_2、MoO_3/SiO_2催化剂的噻吩加氢脱硫、环己烯加氢和苯加氢活性。结果表明:(1)TiO_2的加入有利于加强MoO_3与SiO_2之间的相互作用,促进MoO_3在载体表面的分散,提高其分散阈值:(2)当MoO_3载量低于分散阈值时,其HDS、HYD和BHD活性随MoO_3载量的增加而明显增大,但在高于分散阈值后,几乎保持不变,能明显体现负载型Mo催化剂在HDS、HYD和BHD反应中的阈值效应;(3)MoO_3/TiO_2—SiO_2催化剂的HDS、HYD和BHD活性都较MoO_3/SiO_2催化剂高,TiO_2能很大程度地改善MoO_3/SiO_2催化剂的HDS、HYD活性。     

Synthesis of Novel Ionic Liquid （[C4CNmim]^＋PF6^-） and Application to Preparation of Polyketone

N-valeronitrile-N’-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.     

Effect of support calcination temperature on the Ru-Ce-B/ZrO_2 catalysts for benzene selective hydrogenation to cyclohexene

The effect of support calcination temperature on the benzene selective hydrogenation performance of the Ru-Ce-B/ZrO2 catalysts was investigated.It was found that with increasing calcination temperature,the surface area decreased,on the contrary,the pore size and the amount of monoclinic phase increased.With increasing support calcination temperature,the activity of the catalyst roughly decreased and cyclohexene selectivity increased.The activity decreased due to the decrease of the surface areas.The increase of the cyclohexene selectivity was correlated not only with the decrease of the surface areas but also with the increase of monoclinic phases,rich in surface hydroxyl,and the enlarged pore size of zirconia.This suggests the monoclinic zirconia with a medium surface area,rather than a big one,and a mesoporous structure,even including some macropores,is an ideal support of the catalyst for benzene selective hydrogenation.