Thermal analyses of home-made zeolite by DSC and TG

Volatile organic compounds (VOCs) and greenhouse gases are the main factors involved in pollution control and global warming. Various treatment methods involving incineration, adsorption, etc., have been employed to reduce VOCs and greenhouse gases concentration in the operating environment and atmosphere. Activated carbon, zeolite, silica gel, and alumina have been broadly used to adsorb pollutants in various industrial applications. Based on the promising effect of adsorption, we analyzed and identified the thermal phenomena of home-made zeolite using various instruments. The endothermic reaction under 100?°C of home-made zeolite was identified as steam adsorption, which is an important discovery. The optimal adsorption temperatures of home-made zeolite have been determined at 200?C550?°C.     

ZSM-5/Y复合分子筛在烃类催化裂化催化剂中的应用研究

以大庆减压蜡油为原料，考察了水热脱铝ZSM-5/Y复合分子筛的催化裂化性能，并与经同样条件水热脱铝的ZSM-5和Y型沸石的机械混合分子筛进行了对比研究。结果表明，与机械混合样品相比，复合分子筛具有较大的柴油产率和气体产率，汽油产率降低。从复合分子筛结构和ZSM-5的择形催化两方面分析了复合分子筛和机械混合分子筛裂化性能差别的原因。复合分子筛的聚集体结构不利于大分子进入分子筛结构中进行裂化，有利于汽油组分的裂化。气体数据分析支持了复合分子筛的结构特点。     

ZnCl2/NaY催化邻苯二酚与甲醇醚化反应

ZnCl2/NaY催化邻苯二酚与甲醇醚化反应;固体酸催化剂;愈创木酚     

超声陈化法制备纳米NaY分子筛及形成机理研究

Nano-sized NaY zeolite was synthesized from metakaolin in the hydrothermal synthesis system by using ultrasonic during aging time.The process of crystallizing NaY zeolite was studied by XRD、SEM、ICP OES ,and the formation mechanism of nano-sized NaY zeolite was researched,finally the conditions of synthesizing nano-sized zeolite NaY had been brought forward.     

ZnO-beta zeolite: as an effective and reusable heterogeneous catalyst for the one-pot synthesis of polyhydroquinolines

Abstract

ZnO-beta zeolite, an inexpensive and mild catalyst, has been used for the synthesis of polyhydroquinolines in excellent yields from the one-pot four-component condensation of aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate in ethanol at room temperature. The remarkable advantages offered by this method are a green catalyst, mild reaction conditions, simple work-up procedures, much faster reactions, and excellent yield of products. Furthermore, the catalyst could be reused several times keeping its initial activity in recycled reactions.     

用钙试剂羧酸钠为指示剂络合滴定法测定降水中钙离子

提出用钙试剂羧酸钠作指示剂络合滴定法测定降水中钙离子,在自然条件下终点的观察即能顺利进行。同《空气和废气监测分析方法》中钙离子络合滴定法相比较,此法终点敏锐,回收率为９５％～１００％,相对标准偏差均小于２．７％,方法简便、快速、准确、灵敏。具有推广性。     

Influence of catalyst binder on the acidity and activity/selectivity of Ga/H-ZSM-5 zeolite in propane aromatization

The acidity and initial and time-on-stream activity in propane aromatization (at 550°C, space velocity of 3100 cm³g⁻¹ _(zeolite)h⁻¹) of Ga-impregnated H-ZSM-5 zeolite without or with binders (50 wt%), such as silica, alumina and kaolin, have been investigated. Both the acidity and catalytic activity of the zeolite are influenced by the presence of binder in the catalyst, depending upon the binder. The influence is found to be lowest for alumina and highest for kaolin. Among the binders, alumina is the most preferred binder for the zeolite catalyst.     

Determination of kerogen type by using DSC and TG analysis

The rate of pyrolysis and oxidation of 8 different samples of oil shale kerogen concentrate (KC) were investigated using DSC analysis. Recently performed thermogravimetric studies (TG and DTG) with the same samples of KC indicated that the activation energy of the pyrolysis of specific KCs increases with increasing paraffinic structure in the KC. An opposite effect, i.e. a decrease of the activation energy with an increase of paraffinic structure was determined in the case of KC oxidation. In this study, using the standard ASTM E-698 method based on the determined temperature at which the maximum heat effect could be observed (exo in the case of oxidation and endo in the case of pyrolysis), an activation energy for the pyrolysis, as well as for the oxidation process was determined and also successfully correlated with the content of paraffinic structure of KC. Thus, the higher content of paraffinic structure in KCs indicates that higher values of the activation energy could be determined either in the case of pyrolysis or oxidation followed by DSC analysis.     

负载铂催化剂中沸石载体酸性对甲烷两步转化的影响

考察了具有相同金属分散度的Pt/NaY、Pt/HNaY、 Pt/HY、Pt/NaBeta和Pt/HBeta催化剂中沸石载体的酸性对在低温下（≤250 ℃）甲烷两步等温转化反应以及由甲烷解离吸附产生的表面碳物种分布的影响。由甲烷等温两步转化生成的C2+烃类产物的总量随着载体酸性的增加而明显增加;C2～C6产物的分布也发生了变化。由表面碳物种的程序升温加氢结果表明,在各种催化剂上碳物种的形式是相似的,其总量和具有活性的Cα物种的量均因载体酸性增加而增加,反应性也增大。这种因沸石载体酸性变化而引起的载体效应是由金属和载体的相互作用造成负载在酸性载体上铂粒子的贫电子性而引起,即由金属粒子电子性质的变化而引起的催化性质的变化。     

Thermal Decomposition of Hydrated Lanthanide Picrates by TG/DTG and DSC Analyses

Hydrated lanthanide picrates with a composition of: Ln(pic)₃⋅xH₂O (Ln=La–Lu, Y) were synthesized and characterized. Thermal decomposition of the picrates by TG/DTG and DSC techniques are reported. This revised version was published online in July 2006 with corrections to the Cover Date.     

惰性气氛下准东煤Na/Ca释放特性的研究

基于准东煤中Na/Ca的赋存形态,采用管式加热炉研究了准东煤中Na/Ca在惰性气氛下的释放特性和形态转变。结果表明,水溶态Na_w在加热温度t ≤ 600℃时先转变成不可溶态Na_re,随着温度升高,不可溶态Na_re又重新转变成水溶态Na_w,当加热温度t > 800℃时,Na大量释放。酸溶态Ca_ac在加热温度t ≤ 700℃时先分解生成CaO并且与其他矿物组分反应转变成不可溶态Ca_re,随着温度升高,不可溶态Ca_re逐渐转变成酸溶态Ca_ac和水溶态Ca_w。相同温度条件下,Ca的释放率低于Na的释放率,少量酸溶态有机Ca随挥发分释放而以气相形式释放。     

Selective Hydrogenation of Aromatic Aminoketones by Pd/C Catalysis

We report an alternative hydrogenation of aromatic aminoketones by heterogeneous catalyst of palladium on carbon (Pd/C) in which nitro, in particular carbonyl groups in the ketones, could be selectively transformed to corresponding amino ketone, secondary alcohol, or methylene compound.     

碱液后处理对纳米ZSM-5沸石孔道和酸度的影响

采用XRD、N2物理吸附、NH3-TPD以及TEM、IR和NMR手段,系统研究了NaOH碱液后处理对低硅铝比纳米ZSM-5沸石(Si/Al摩尔比为14.5、晶粒度为20～50 nm)孔道和酸度的影响.结果表明,在碱液中,低硅铝比纳米ZSM-5沸石主要发生限域脱硅,而且低硅铝比纳米ZSM-5沸石的碱液脱硅难度大于高硅铝比沸石.但在适当的碱液处理条件下(碱硅比为0.19～0.35,温度为60～80℃,处理时间为2～5 h)可以在其晶体内产生大量介孔,增加比表面积和孔容;同时增加弱酸和中强酸的浓度,并提高L酸比例.L酸的大量增加主要是由于产生了裸露的骨架铝(≡Alδ+),这与文献的观点有所不同.     

Low/high temperature relationships in dinitramide salts by DEA/DSC and study of oxidation of aluminum powders by DSC/TG

The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship between the DSC rate of decomposition at the peak maximum and the DEA tan value at the low temperature transition peak. As the cation basicity increased in the series ADN相似文献   

Synthesis of Renewable Diesel through Hydrodeoxygenation Using Pd/zeolite Catalysts

Hydrodeoxygenation of oleic acid as model compound of vegetable oils over Pd/zeolite catalysts was investigated under conditions of 375−400 °C and 15 bar in a semi batch stirred autoclave reactor. Pd/zeolite-1 and Pd/zeolite-2 catalysts were prepared using microwave polyol method with different treatment conditions. The liquid hydrocarbon products named Renewable Diesel have suitable density and viscosity, and quite high cetane index in accordance with standard commercial diesel and ASTM D-975. The IR spectrum of Renewable Diesel products have similarities with commercial diesel. The oxygenation removal pathway of oleic acid over Pd/zeolite 1 catalyst was primarily compiled through decarboxylation at 375 °C.     

铯改性的沸石Y上醇类和胺类的氰乙基化反应SaraZamanian,AliNematiKharat简

Zeolite Y modified by cesium and magnesium ions was prepared by ion-exchange and impregnation methods, and its activity in the cyanoethylation of aliphatic and aromatic alcohols and amines was investigated. During the preparation of some samples, the transformation of zeolite Y into a pollucite-type phase occurred. This phase exhibited good activity in the cyanoethylation of aliphatic alcohols. The prepared solids modified by the impregnation method were more active than the ion-exchanged solids. The activities of the catalysts, in contrast to other basic solids, were scarcely affected by the presence of air or moisture. A correlation between catalyst basicity and catalytic activity is discussed. The catalysts were characterized by X-ray diffraction, volumetric nitrogen adsorption surface area measurement, and CO₂ temperature-programmed desorption. Scanning electron microscopy revealed that the particles of the modified nanocatalysts were < 40 nm. The reaction of acrylonitrile with linear alcohols in the presence of the catalysts was accelerated by microwave irradiation.     

Ca/Al固体碱催化菜籽油制备生物柴油

采用共沉淀法制备了Ca/Al复合氧化物固体碱催化剂,考察了沉淀剂种类、Ca/Al摩尔比、沉淀温度、溶液pH值、老化时间和焙烧温度等制备条件对其催化剂活性的影响。采用正交实验方法得到制备Ca/Al复合固体碱催化剂前躯体的最佳制备条件为,沉淀剂NaOH,Ca/Al摩尔比为3,沉淀温度为60 ℃,沉淀过程中pH值保持在10,在90 ℃老化18 h。在该最优条件下制备的催化剂前驱体主要以Ca₄Al₂O₆(NO₃)₂·10H₂O晶相存在,在N₂气保护下300 ℃焙烧2 h后,催化剂形成高分散钙铝复合氧化物,且碱性强度达到26.5以上。在催化菜籽油和甲醇的酯交换反应中,菜籽油的转化率达到95%,脂肪酸甲酯的质量分数为95.9%。     

柠檬酸溶液中NaY分子筛的脱铝行为

硅铝分子筛有机酸配合脱铝是提高其稳定性、引入介孔的一种重要方法.采用X射线衍射、N₂物理吸附、高分辨透射电镜、傅里叶变换红外光谱、²⁷Al和²⁹Si固体魔角自旋核磁共振光谱等方法研究了NaY分子筛柠檬酸脱铝行为.结果表明,柠檬酸浓度对NaY分子筛骨架Al原子的脱出影响尤为显著.反应起始阶段,分子筛骨架铝原子快速脱出,其晶体结构遭到严重破坏.随着反应的进行,分子筛硅铝比和结晶度皆有所增加,表明其骨架结构可能进行了重新排列.75℃下,0.10 mol/L柠檬酸处理2 h的脱铝分子筛样品,与NaY分子筛样品相比,其骨架硅铝比增加了0.6、外表面增加了17 m²·g^-1,脱铝同时产生了大量无定形硅.     

Kinetics of the oxidation of magnetite using simultaneous TG/DSC

Kinetics of the oxidation of magnetite (Fe₃O₄) to hematite (a-Fe₂O₃) are studied in air using simultaneous TG/DSC. The mechanism is complex and the differences between the kinetic conclusions and Arrhenius parameters based on either TG or DSC are discussed. As in our previous work on CaCO₃ [1], the determination of a satisfactory baseline for the DSC results adds considerable uncertainty to those kinetic results. Consequently the calculations based on the TG data are considered superior. Solid state reactivity varies from one source of material to another and the results are compared for two different commercial samples of magnetite, both presumably prepared by wet chemical methods. These materials are much more reactive than the material studied previously [2], which had been coarsened and refined at high temperatures. In that earlier study, the metastable spinel, g-Fe₂O₃, was formed as an intermediate in the oxidation to the final stable form, a-Fe₂O₃. The exothermic reaction of the gamma to alpha form of the product during the oxidation process destroys the direct comparison between the TG and DSC results, since the former only detects the change in mass of the sample and not the crystallographic transformation. The TG results, however, represent the true oxidation process without superposition of the structural aspects. This revised version was published online in July 2006 with corrections to the Cover Date.     

乳酸丁酯的非均相催化合成

在Ga2 O3负载量为20％,500℃焙烧2h的条件下制备了固体酸催化剂Ga2 O3/SiO2,利用红外光谱分析对催化剂进行了表征.将其用于非均相催化合成乳酸丁酯的反应,考察了催化剂用量、n(正丁醇)∶n(乳酸)、环己烷用量、反应时间和催化剂重复使用性能等因素对酯化率的影响.结果表明,该催化剂催化合成乳酸丁酯的适宜反应...