Highly efficient V-Mo-Fe-O catalysts for selective oxidation of toluene to benzaldehyde

The V-Mo-Fe-O catalysts were synthesized by a sol-gel method, characterized and used for the selective oxidation of toluene to benzaldehyde with hydrogen peroxide. The results show that V-Mo-Fe-O catalyst is an effective catalyst, exhibiting a toluene conversion of 40.3%, and a benzaldehyde selectivity of 84.5% at 80 °C. Scanning electron microscopy (SEM) shows that the catalyst has nanorod structure with a thin layer compound, which may be constitutive of iron molybdate while the main compound of catalyst is MoV₂O₈. Furthermore, the catalyst can be easily recycled and reused for four times without significant changes in its activity.     

Highly efficient non-noble metal based nanostructured catalysts for selective CO methanation

Highly efficient non-noble metal based catalysts (Zr_1 − xNi_xO₂) showed outstanding catalytic performance at lower temperature for selective CO methanation. The characterization techniques revealed that Zr_1 − xNi_xO₂ catalyst contained uniformly dispersed Ni particles with strong interaction between Ni and ZrO₂.     

Highly efficient sulfur and coking resistance catalysts for tar gasification with steam

Ni-on-dolomite catalysts were found to be effective catalysts for coking resistance and promising sulfur tolerance for steam reforming of tar. Experiments were carried out in a fixed bed reactor at 730–850 °C with a short contact time (W/F: 0.55 g h/mol) and under atmospheric pressure. Toluene and naphthalene were selected as the model component of tar. The process variables such as calcination temperature, reaction temperature and the content of nickel had substantial influence on promising sulfur tolerance in catalytic tar removal by Ni/Dolomite catalysts. Results were compared with the Ni/Al₂O₃, Ni/SiO₂ as a representative of commercial catalysts. The novel 15%Ni/Dolomite almost gasified tar component even at 770 °C and the presence of 100 ppm H₂S in the feed. The poisoning effect of H₂S was discovered to be reversible. The suppression of the catalytic activity by adding H₂S was much lower for Ni/Dolomite than Ni/Al₂O₃. The TGA–DTA analysis of used catalysts revealed that Ni/Dolomite exhibited high resistance to coke deposition over those of the Ni/Al₂O₃, Ni/SiO₂.     

Highly efficient palladium catalysts supported on nitrogen contained polymers for Suzuki-Miyaura reaction

Through Pd catalyzed CN coupling reaction, Pd nanoparticles and diadamantylphosphine ligand were immobilized in situ into the formed N contained polymers as heterogeneous Pd catalysts for Suzuki-Miyaura reaction. The Pd@NPad₂-1.0 catalyst was found to be highly efficient and only 4 ppm of Pd (Pd@NPad₂-1.0) was required for the coupling of aryl bromides with phenylboronic acid, and the corresponding products were obtained in good to excellent yields with high TON and TOF as 250,000 and 41,666 h^− 1 respectively. Moreover, the coupling of various aryl chlorides with phenylboronic acids gave the corresponding products in high yields also. And the Pd@NPad₂-1.0 catalyst is reusable at least 5 times with only slight deactivation.     

三维有序大孔钙钛矿金属氧化物作为高效燃烧催化剂的研究进展

三维有序大孔（3DOM）材料因为具有独特的结构、可调的组成、高稳定性、高电子传递能力以及高比表面积而引起很多学者的研究兴趣。本文主要介绍了3DOM钙钛矿材料作为催化剂或载体在催化碳烟、挥发性有机物和甲烷燃烧方面取得的成果,分析了制备条件、结构特征对催化性能的影响;指出了3DOM钙钛矿材料具有优异的催化燃烧稳定性、高分子吸附和扩散能力以及高氧迁移率,能够显著降低氧化还原温度和表观活化能,因此可以作为高效燃烧催化剂。最后提出了未来研究重点和发展方向,在未来的研究中应该开发出更多可以与贵金属相媲美的廉价的新型3DOM材料以拓展3DOM材料应用范围。另外,3DOM 材料表面性能的提升以及用于催化燃烧的作用机理需进一步深入研究。     

Highly efficient catalysts for the synthesis of adipic acid from cis,cis-muconic acid

Performing catalysts have been synthetized through incipient wet impregnation and tested for cis,cis-muconic acid hydrogenation to adipic acid. The activity of Pt-based catalysts has been compared with an Ni-based catalyst at a gentle condition. A supported 14.2 wt% Ni on γ-alumina converted 100% of muconic acid, yielding 99.4 mol% of adipic acid.     

Influence of combustion aids on suspension combustion synthesis of mullite powders

Mullite powders were obtained by suspension combustion synthesis. The reaction was performed in a combustion reactor designed in the laboratory, which presents some advantages over other classical procedures (heating with a hot-plate, a furnace or a microwave oven). Aluminium nitrate, as a source of Al, and either TEOS or a colloidal silica suspension, as a source of Si, were used as reagents. Urea, at either 100 or 200% excess over the stoichiometric ratio, was used as fuel. NH₄NO₃, HNO₃, NH₄Cl and H₂O₂ were compared as combustion aids. Mullite phase with a high crystallinity and a high specific surface area was directly obtained by using aluminium nitrate, colloidal silica suspension, a 100% excess of urea and either NH₄NO₃ or H₂O₂. The selection of a combustion aid determines the characteristics of the as-synthesized powders. In addition to enthalpy predictions the reduction potential is a key parameter for the combustion to occur.     

Electrochemical catalysts for hydrocarbon combustion

Two series of electrochemical catalysts were prepared from sputtered Pt thin films onto two kinds of electrolyte membranes, 8 mol% Y₂O₃-stabilized ZrO₂ (YSZ), an O²⁻ conducting oxide and Na₃Zr₂Si₂PO₁₂ (NASICON), a Na⁺ one; respectively. The thickness of the Pt films varied from 8 to 120 nm. Therefore, the Pt loading was extremely low. The catalytic activity of Pt/YSZ and Pt/NASICON systems has been investigated between 200 and 500 °C for propane and propene, respectively. In spite of the low Pt loading, the Pt/YSZ electrochemical catalysts exhibited high activity for propane combustion. Furthermore, the catalytic activity can be in-situ controlled by applying electrical polarisation with high Faradaic efficiency (10³). The catalytic rate of propene deep oxidation on Pt/NASICON electrochemical catalyst was found to be limited by the number of active sites, which is low on very thin Pt films. Moreover, initial anodic polarisation indicate that Na⁺ ions are already present on the top surface of Pt, probably proceeding from the preliminary stabilisation treatment of Pt in the reactive mixture. Nevertheless, polarisation allows the tuning of the catalytic activity of the electrochemical catalysts for propene oxidation. Finally, for both kinds of electrochemical catalysts, our results have evidenced that the measurement of the open-circuit voltage during catalytic process can be an indicator of the hydrocarbon conversion.     

Highly efficient Pd-Fe/Ni foam as heterogeneous Fenton catalysts for the three-dimensional electrode system

A novel particle electrode (PE) Pd-Fe/Ni foam was synthesized and used for Dimetridazole (DMZ) degradation in the three-dimensional electrode (3D) system. Results showed that Pd-Fe/Ni foam exhibited excellent electrocatalytic activity and satisfactory electrocatalytic stability. Inducing Pd and Fe species could not only decrease the resistance and accelerate the electron transfer, but also cause synergistic effect. In the 3D system with Pd-Fe/Ni foam PEs, DMZ degradation was much more efficient as compared with those using Ni foam PEs, Fe/Ni foam PEs and Pd/Ni foam PEs, owing to direct electrolysis, and efficient production of H₂O₂ and ·OH of Pd-Fe/Ni foam PEs.     

Effect of Lead and Copper Methylene Disalicylates on the combustion rates of double-base rocket propellants

The effect of lead and copper methylene disalicylates and their mixtures was studied on the burning rates (35 kg/cm²-140 kg/cm²), heat of explosion, stability and thermal decomposition of double-base propelants. The results indicate that these salts are very effective catalyst and their mixtures produce super-rate burning (140% increase) with a uniform pressure index value in the entire pressure range. These additives lower “n” value to about 0.2–0.3 in some of the pressure regions. Results of DTA study suggest that these additives decompose in an exothermic mode in the temperature range close to the surface temperature of double base propellants.     

Role of Additives in Combustion Waves and effect on stable combustion limit of double-base propellants

The effect of additives on the flame structures and the burning rates of double-base propellants have been examined by means of photographic observations and temperature profile measurements. The additives used for this study are lead salicylate (PbSa, 2%), nickel (Ni, 1%), ammonium perchlorate (AP, 30%), and cyclotetramethylene tetranitramine (HMX, 30%). The addition of PbSa increases the burning rate, but does not improve the flame temperature characteristics. The addition of Ni increases the flame temperature significantly at pressures below 30 atm. The Ni acts as a catalyst to promote the flame reaction while it does not act as a burning rate modifier. The additions of AP and HMX increase the thermal performance of the propellant system, however, the HMX does not improve the stable combustion limit of the rocket motor at low pressures. The addition of Ni or AP is found to increase the flame temperature at pressures below 30 atm, and the stable combustion limit is lowered to below 3 atm.     

静电纺丝法制备高活性多孔Ni/SiO2甲烷化催化剂

以三嵌段共聚物P123为模板剂,采用静电纺丝法制备了多孔Ni/SiO₂催化剂,考察其在CO甲烷化中的催化性能。采用N₂物理吸脱附测试、扫描电子显微镜（SEM）、X射线衍射（XRD）、H₂-程序升温还原（H₂-TPR）、透射电子显微镜（TEM）、热重分析（TGA）对催化剂的结构性质进行表征。结果表明,静电纺丝法制备的多孔Ni/SiO₂催化剂活性组分Ni在SiO₂载体纤维上高度分散,比表面积大,Ni颗粒尺寸小,金属与载体相互作用强,在CO甲烷化反应中表现出优异的催化活性和稳定性。在温度450℃,压力0.1 MPa,质量空速15000 ml/（g·h）条件下,多孔Ni/SiO₂催化剂CO转化率最高可达96.4%,CH₄选择性可达86.4%。此方法为工业上制备高催化活性且无须二次成型的甲烷化催化剂提供了新思路。     

Highly efficient cis-1,4 polymerisation of isoprene using simple homoleptic amido rare earth-based catalysts

Polymerisation of isoprene was performed by means of ternary catalytic systems made of Ln[N(SiMe₃)₂]₃ (Ln = Nd (1), Y (2))/borate/Al(ⁱBu)₃ combinations (borate = [HNMe₂Ph][B(C₆F₅)₄] (HNB), [CPh₃][B(C₆F₅)₄] (TB) or B(C₆F₅)₃ (Barf)). With borate activator B(C₆F₅)₃, highly active (up to 4700 kg mol⁻¹h⁻¹) and selective catalysts are obtained with both neodymium and yttrium metals, leading up to 96% cis-1,4-polyisoprene.     

Self-propagating chain combustion with formation of ultradispersed powders

We have investigated the possibility of realizing the self-propagating combustion regime for a gaseous mixture of SiH₄–NH₃–O₂ and SiH₄-2 with an oxygen content of 0–2%. Calculation of the equilibrium composition indicates the possibility that the target products Si and Si₃N₄ are formed. We have established experimentally that propagation of the chemical reaction front in the self-sustaining regime with formation of the above-indicated products occurs only in the presence of oxygen. We show that chemical induction, leading to consumption of up to 60% of the initial monosilane, is a chain reaction.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka 142432. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 4, pp. 85–91, July–August, 1994.