稀土固体超强酸SO2-4/TiO2/Sm3+催化合成二芳基乙烷的研究

二甲苯和苯乙烯的混合物,在稀土固体超强酸SO2-4 /TiO2/Sm3+的催化下发生傅-克烷基化反应,合成二芳基乙烷.研究了催化剂的催化性能,同时考察了影响合成反应的因素.结果表明,稀土固体超强酸SO2- 4/TiO2/Sm3+具有催化性能高,性能稳定和连续催化活性基本保持不变的优点,而且生产过程简单,无腐蚀,无废水污染.     

稀土固体超强酸SO_4~(2-)/TiO_2/Sm~(3+)催化合成二芳基乙烷的研究

二甲苯和苯乙烯的混合物,在稀土固体超强酸SO2 -4/TiO2 /Sm3 + 的催化下发生傅-克烷基化反应,合成二芳基乙烷。研究了催化剂的催化性能,同时考察了影响合成反应的因素。结果表明,稀土固体超强酸SO2 -4/TiO2 /Sm3 + 具有催化性能高,性能稳定和连续催化活性基本保持不变的优点,而且生产过程简单,无腐蚀,无废水污染。     

稀土固体超强酸SO4^2-／TiO2／Sm^3＋催化合成己二酸二异辛酯的研究

以稀土固体超强酸SO4^2-/TiO2/Sm^3 为催化剂合成了己二酸二异辛酯，考察了影响酯化反应的因素。实验结果表明，稀土固体超强酸SO4^2-/TiO2／Sm^3 催化活性高、性能稳定，是一种优良的醇化催化剂。     

固体超强酸SO2-4/TiO2/La3+催化合成二甲基丙烯酸丁二醇酯

以自制稀土改性固体超强酸SO2-4/TiO2/La3+为催化剂,高效合成了二甲基丙烯酸丁二醇酯.比较了不同催化剂的催化活性,并考察了固体酸的制备条件及酯化反应条件对催化活性的影响,得到最佳合成条件为:SO2-4/TiO2/La3+于500 ℃下活化3 h,n(酸)∶n(醇)=2.8∶1,阻聚剂、催化剂质量分数分别为1.0%和1.2%,反应温度维持在120 ℃左右反应2 h左右,酯化率可达92.0%.     

稀土固体超强酸SO_4~(2-)/TiO_2/La~(3+)催化合成邻苯二甲酸二(2-乙基)己酯

以稀土固体超强酸SO42-/TiO2/La3+为催化剂,邻苯二甲酸酐和2 乙基己醇为原料,合成邻苯二甲酸二(2 乙基)己酯,考察了影响反应的因素。结果表明,醇∶苯酐(质量比)=2.5∶1,催化剂用量为苯酐的5%,反应时间2 5h时,酯化率可达92.7%。     

合成己酸异戊酯的催化剂研究

综述了氯化铁等Lewis酸 ,硫酸氢钠 ,硫酸钛 ,对甲苯磺酸 ,固体超强酸TiO2 /SO42 -,稀土固体超强酸SO42 -/TiO2 /La3 + ,磷钨杂多酸 ,TABP等几种不同催化剂催化合成了己酸异戊酯的实验结果。结果表明 :硫酸氢钠 ,磷钨杂多酸 ,TABP等 3种催化剂对合成己酸异戊酯的酯收率较高 ,具有实际应用价值。     

稀土固体超强酸SO_4~(2-)/TiO_2/Ce(Ⅳ)催化合成邻苯二甲酸二辛酯

以苯酐和2-乙基己醇为原料,稀土固体超强酸SO42-/TiO2/Ce(Ⅳ)为催化剂,合成了邻苯二甲酸二辛酯。考察了影响反应的因素。结果表明,醇∶苯酐(摩尔比)=3∶1,催化剂用量占反应物总质量的1%,反应温度为205℃,反应时间3 h时,酯化率可达97%以上。     

固体超强酸催化合成乙酸正丁酯的研究

文章采用TiO2/SO42-固体超强酸为催化剂来合成乙酸正丁酯,考察了催化剂用量、酸醇物质的量之比、反应时间等因素对酯化率的影响,结果表明,TiO2/SO42-固体超强酸催化剂活性高,易分离,对设备不腐蚀,排放无污染等优点;在最佳反应条件下,酯化率可达99.3%。     

SO_4~(2-)/TiO_2-Al_2O_3催化合成新戊二醇椰子油酸酯

以SO42-/TiO2-Al2O3固体超强酸为催化剂,进行新戊二醇和椰子油酸的酯化反应,合成了新戊二醇椰子油酸酯,考察了酸醇摩尔比、催化剂用量、反应温度、反应时间等条件对酯化反应的影响。结果表明,较优的合成条件为:n(椰子油酸)∶n(新戊二醇)=1.95∶1,催化剂用量为总反应物质量的0.040%,200℃下回流反应7 h。在此条件下,SO42-/TiO2-Al2O3固体超强酸有较高的催化活性,酯化率达97.0%,且催化剂重复使用5次仍保持较高活性。     

固体超强酸SO2-4/TiO2/La3+催化合成氯乙酸乙酯

以稀土固体超强酸SO2-4/TiO2/La3+为催化剂,氯乙酸与乙醇为原料合成氯乙酸乙酯.研究了氯乙酸与乙醇的摩尔比、催化剂用量、环己烷的用量、反应时间诸因素对产品收率的影响.结果表明SO2-4/TiO2/La3+是合成氯乙酸乙酯的良好催化剂,适宜的反应条件如下氯乙酸与乙醇的摩尔比为1∶3.0,催化剂的用量0.8 g,环己烷用量15 mL,反应2.0 h,氯乙酸乙酯的收率可达92.7%.     

Low-temperature catalytic combustion on Pt/SO 4 2− /ZrO2 and Pd/SO 4 2− /ZrO2 catalysts

Low-temperature combustion of various organic compounds on Pt/SO ₄ ^–2 /ZrO₂ and Pd/SO ₄ ^–2 /ZrO₂ was studied. For these organic compounds, especially saturated hydrocarbons, the combustion activities of Pt/SO ₄ ^–2 /ZrO₂ are higher than those of Pt/ Al₂O₃. Pt/SO ₄ ^–2 /ZrO₂ combustion catalysts can be used in a wide range of space velocity and oxygen content. The catalytic activity is enhanced with an increase of Pt loading from 0.1 to 1.0 wt%. The superacidity of the support material is responsible for the improvement in activity rather than an increase in catalyst surface area or metal dispersion. Pd/SO ₄ ^–2 /ZrO₂ are less active than Pt/SO ₄ ^–2 /ZrO₂.     

H2S adsorption on polycrystalline UO2

We report results on the adsorption and desorption of H₂S on polycrystalline UO₂ at 100 and 300 K, using ultrahigh vacuum X-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS), and temperature programmed desorption (TPD). Our work is motivated by the potential for using the large stockpiles of depleted uranium in industrial applications, e.g., in catalytic processes, such as hydrodesulfurization (HDS) of petroleum. H₂S is found to adsorb molecularly at 100 K on the polycrystalline surface, and desorption of molecular H₂S occurs at a peak temperature of 140 K in TPD. Adsorption rates of sulfur as a function of H₂S exposure are measured using XPS at 100 K; the S 2p intensity and lineshapes demonstrate that the saturation coverage of S-containing species is 1 monolayer (ML) at 100 K, and is 0.3–0.4 ML of dissociation fragments at 300 K. LEIS measurements of adsorption rates agree with XPS measurements. Atomic S is found to be stable to >500 K on the oxide surface, and desorbs at 580 K. Evidence for a recombination reaction of dissociative S species is also observed. We suggest that O-vacancies, defects, and surface termination atoms in the oxide surface are of importance in the adsorption and decomposition of S-containing molecules.     

CaO-MgO-SiO2-H2O体系的热力学基础研究

本文从热力学角度系统研究了CaO-MgO-SiO     

Reduction of NO by H2 and CO on Pt/TiO2/SiO2

Different catalysts based on platinum and a silica, titania or mixed titania/silica support were studied in NO reduction reactions by CO and H₂ in the temperature range of 25–400C. The mixed oxide catalysts showed considerably lower onset temperatures in NO/CO reactions but this coincided with a maximum in N₂O formation. In NO/H₂ reactions all titania containing catalysts produced more N₂O than silica supported platinum at low temperatures but were more selective to N₂ at high temperatures.     

Numerical Analysis on the Characteristics of Soot Particles in C2H4/CO2/O2/N2 Combustion

The purpose of this study is to investigate the characteristics of soot particles in C₂H₄/CO₂/O₂/N₂ combustion at equivalence ratio of 3.0-5.0. As the oxidant is switched from conventional air to CO₂/O₂/N₂ mixture, the key species C₂H₂, C₃H₃ responsible for formation of first aromatic ring, the typical aromatics and 4-ring aromatics total production rate all decrease greatly. In addition, with CO₂ mole fraction from 0.2 to 0.5 in the mixture, the soot particle number density, volume fraction, surface area density, which are three most important parameters to soot particle property, are suppressed obviously. Furthermore, the increasing content of CO₂ in the oxidizer influences mostly H, OH radical concentrations by two reactions: CO+OH=CO₂ H and H+O₂=O+OH, and the production rate of H, OH from the two reactions declined, which revealed that CO₂ in mixture has an inhibiting effect on soot particle generation.     

Oxygen reduction on Ag-MnO2/SWNT and Ag-MnO2/AB electrodes

Bifunctional catalysts (Ag-MnO₂)/SWNT were prepared by using a simple chemical reduction route on single-walled carbon nanotubes (SWNT). Five weight percentage of Ag-MnO₂ on SWNT was found to be the best loading in terms of current density. The (Ag-MnO₂)/SWNT catalyst was characterized and the kinetics towards oxygen reduction reaction (ORR) was determined and compared with that of Ag-MnO₂ on acetylene black (AB) catalyst. The number of exchanged electrons for the ORR was found to be close to four on both (Ag-MnO₂)/SWNT and (Ag-MnO₂)/AB. The kinetic rate constant of catalytic reaction for the two catalysts was of the same order. The zinc-air batteries with both catalysts were fabricated and examined. A stable discharge potential plateau appeared at approximately 1.2 and 1.1 V with discharge capacities 261 and 190 mAh/g, respectively.     

Hydrodesulfurization on MoS2/MgO

A series of Mo/MgO catalysts with loadings ranging from 2–12 wt% Mo were studied by oxygen chemisorption, X-ray diffraction and activity for thiophene hydrodesulfurization (HDS) reaction. The results obtained from the above measurements are compared with those on Mo/--Al₂O₃. These results indicated that molybdenum is better dispersed on MgO. Hydrodesulfurization activity per g. Mo is found to be higher in the case of Mo/MgO. The higher activities are attributed to the increase in dispersion of Mo on MgO. A linear correlation is obtained between oxygen chemisorption and HDS activity. The parallelism between HDS and oxygen chemisorption is explained.     

Differential Thermal Analysis on the Crystallization Kinetics of K2O-B2O3-MgO-Al2O3-SiO2-TiO2-F Glass

The crystallization kinetics of a glass based on one type of mica, NaMg₃AlSi₃O₁₀F₂, with the addition of a nucleating agent, TiO₂, has been studied using differential thermal analysis (DTA) under both isothermal and nonisothermal conditions. Two distinct crystallization exotherms in the DTA curve are observed and resolved that correspond to the initial formation of magnesium titanate (MgTi₂O₅) and the later formation of mica. The activation energy for precipitation of each crystalline phase has been evaluated, and the crystallization mechanism has been studied. The results indicate that the growth of mica is a two-dimensional process, controlled by the crystal-glass interface reaction. The average calculated values of activation energies are 256 ± 11 kJ/mol and 275 ± 6 kJ/mol for the precipitation of MgTi₂O₅ and mica from the glass matrix, respectively.