Oxidative degradation of EVA copolymers in the presence of catalysts

A study of the catalytic degradation of EVA copolymers under air atmosphere has been carried out using thermogravimety (TG). Three commercial EVA copolymers and five zeolites and related materials catalysts have been selected. The degradation process in air atmosphere involves four main decomposition steps (as observed in TG), being more complex than the corresponding process in inert atmosphere. The presence of MCM-41, HY and H-β does not seem to noticeably affect to the overall degradation temperature, despite the temperature of maximum reaction rate for the second decomposition step being slightly displaced towards lower temperatures. Contrarily, the presence of HZSM-5 and HUSY zeolites seems to displace the main stage of the oxidative degradation process towards higher temperatures. Moreover, the relative importance of the second and third decomposition step is different depending on the amount and the nature of the zeolite mixed with the EVA sample. The results obtained show that the presence of the catalyst also enhances the formation of the carbonous residue.     

Effect of zeolite, kaolin and alumina during cracking of heavy petroleum residue evaluated by thermogravimetry

This work evaluates the effect of the FCC catalyst components—Y zeolite, kaolin and alumina—on the formation of coke during the cracking of heavy residue (HR) of petroleum. The Y zeolite, kaolin and alumina were mixed with a HR at a ratio of approximately 1:4. The effect was studied using dynamic thermogravimetry at a heating rate of 50 K min⁻¹, with N₂ (between 35 and 700 °C) and air (in the 700–1,000 °C temperature range). The HR analyzed in these conditions formed 8.1% of coke. All the mixtures presented larger coke formation than that observed in pure HR. The Y zeolite presented fourfold larger coke formation, while kaolin and alumina showed twofold higher formation than pure HR. The major focus of this study was to verify the sensitivity of the TG technique in providing information about coke formation in the fluid catalytic process of refineries.     

用新方法催化合成6-乙酰基-1-甲基环己烯

室温下用HY沸石取代传统催化剂通过1-甲基环己烯与乙酐的酰基化反应合成了6-乙酰基-1-甲基环己烯，考察了HY沸石的SiO2／Al2O2摩尔比、用量和活化时间以及反应时间对该酰化反应的影响．当1-甲基环己烯／乙酐／HY沸石(SiO2／Al2O3摩尔比=29)=1mmol／10mmol／0．200g、反应温度25℃、反应时间3h时，所得酰化产品的产率为60％，HY沸石能够回收和重新使用，显示出与新鲜催化剂几乎相同的催化活性．     

甲基噻吩在HY分子筛上的吸附、脱附及转化行为

由NH₄Y分子筛制备了HY分子筛,运用N₂吸附、NH₃-TPD和Py-FTIR等手段表征HY分子筛的物化性能;采用智能重量分析仪(IGA)方法研究了甲基噻吩(2-甲基噻吩、3-甲基噻吩)在HY分子筛上的吸附-脱附行为;采用程序升温脱附-质谱(TPD-MS)联用手段研究了甲基噻吩在HY分子筛上的转化行为。结果表明,在200 ℃下 2-甲基噻吩和3-甲基噻吩在HY分子筛中的强B酸上发生强化学吸附作用,与B酸结合后生成了甲基噻吩的碳正离子结构进而发生了歧化反应、脱烷基反应以及裂化反应;与2-甲基噻吩不同的是,3-甲基噻吩与HY通过一定的氢转移反应生成了3-甲基四氢噻吩,且200 ℃吸附条件下3-甲基噻吩比2-甲基噻吩更容易发生裂化反应。     

Synthesis and characterization of geopolymer-zeolites from Ghanaian Kaolin samples by variation of two synthesis parameters

Two kaolinitic clays from two Regions of Ghana: Western and Volta Regions, were first calcined at 600 °C for 2 h to transform into the amorphous aluminosilicate phases. The effects of kaolin and alkali ratio as well as aging on the amount and types of zeolite in the resultant geopolymers were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transformed spectroscopy, thermogravimetric analysis and specific surface area measurements. Alkali activation treatment of the metakaolin yielded bulk materials with different amounts and types of zeolite and different particle size distributions. The results showed that initial kaolin samples were dependent on the concentration of alkali treatment and crystallization time during the activation treatment and produced zeolite type A along with quartz which showed no reactivity regardless of the variation of the synthesis parameter.

     

Study of degradation kinetics of sunflower oil on H-Beta zeolite

In this study, were studied the degradation of pure sunflower oil and mixed with H-Beta zeolite. This zeolite was synthesized by the hydrothermal method, followed by calcination and ion exchanged. The characterization of the zeolite was performed by X-ray diffraction and nitrogen adsorption/desorption by the method of BET. The analysis showed that H-Beta zeolite presented a good crystallinity and the template was completely removed from the catalyst. The thermal and catalytic degradation study was carried out using the TG/DTG method in multiple heating rates of 5, 10, and 20 °C min⁻¹. The isoconversion method proposed by Vyazovkin was applied to determine the kinetic parameters for degradation of the sunflower oil. The activation energy for the degradation process of pure sunflower oil was 193 kJ mol⁻¹, while for sunflower oil mixed with 20% of H-Beta zeolite was equivalent to 88 kJ mol⁻¹. It was verified that for the degradation of 90% of the sunflower oil mixed with H-Beta, for a period of 1 h, a temperature of 356 °C was required, whereas for the pure vegetable oil, this value was of 387 °C, at the same time period, showing that the catalyst was effective for the degradation process of sunflower oil.     

Correlation of physical-chemical properties of healthy and pathologic human bones

Summary In this work the properties of HY zeolite containing nickel oxide was investigated using thermal analysis (TG/DTA) and temperature programmed reduction (TPR). The results obtained by XRD and FTIR showed that the impregnation method used did not change the structure of HY zeolite. TPR profiles showed two events at 238 and 507°C which were attributed to reduction of nickel oxide on the HY cavities at different temperatures. The thermodesorption of n-butylamine from Ni*/HY zeolite showed typically two larger mass loss events attributed to the elimination of n-butylamine adsorbed on the weak acid sites and on the medium+strong acid sites.     

Feedstock recycling of polyethylene over AlTUD-1 mesoporous catalyst

The catalytic degradation of high density polyethylene (HDPE) was investigated using AlTUD-1 as catalyst, a recently discovered mesoporous aluminosilicate. The catalytic activity of AlTUD-1 was evaluated by TGA measurements, using a polymer/catalyst ratio of 9:1. AlTUD-1 has a Brønsted acidic behaviour, three-dimensional (3D) connectivities and a pore diameters between 2 and 50 nm. Compared to HY zeolite, the large pore size of AlTUD-1 enhances a selective catalytic degradation of the polymer and prevents rapid deactivation. Moreover, the apparent activation energy of polymer cracking is much lower than with HY zeolite. For these reasons, AlTUD-1 is a potentially interesting catalyst for the catalytic cracking of plastic waste into liquid fuels.     

Silicalite-1修饰的HY型分子筛及其对纤维素水解的催化性能

采用silicalite-1对HY型分子筛进行修饰,得到具有核壳结构的复合分子筛HY/silicalite-1。通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、N2的吸附-脱附及吡啶吸附红外(Py-FTIR)等手段对不同晶化时间合成的HY/silicalite-1复合分子筛进行了表征,研究了复合分子筛对纤维素水解的催化性能。结果表明,晶化时间直接影响复合分子筛的晶体生长规律和两组分的相对含量,最佳晶化时间为16-24 h,所得到的复合分子筛外貌呈核壳结构,silicalite-1附晶生长在HY型分子筛的表面;随着晶化时间的延长,复合分子筛的表面由胶浊状变为光滑,最终变为鳞片状;其B酸量先减少后增加,而L酸量则先增加后减少。其中,晶化时间为24 h的HY/silicalite-1复合分子筛B酸量最大,L酸量最小,对纤维素水解反应具有良好的催化性能,葡萄糖收率由HY型分子筛催化获得的28.0%大幅提高至45.8%。     

Catalytic coprocessing of waste plastics and petroleum residue into liquid fuel oils

Waste plastics of different types were catalytically coprocessed with petroleum residue of light Arabian crude oil in the presence of a number of catalysts. The purpose of the study was to explore effects of various conditions such as catalyst type, amount of catalyst, reaction time, pressure and temperature on the product distribution. The waste plastic studied included low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS) and polypropylene (PP). A series of single (waster plastic with catalyst) and binary (waste plastic and residue with catalyst) reactions were carried out in an autoclave reactor under variable reaction conditions. The reaction conditions used were 1, 3 and 5 wt.% catalysts, 30–120 min reaction time, 400–430 °C reaction temperature and 500–1200 psi hydrogen pressure. The product distribution achieved for residue/plastic/catalyst system showed higher yields of liquid fuels as compared to residue/plastic system. Hydrocarbon gases were formed as well along with heavy oils, insoluble gums and coke. At the reaction conditions of 3 wt.% NiMo catalyst, 90 min reaction time, 1200 psi hydrogen gas pressure, 430 °C temperature and residue to plastic feed ratio of 3:2 (wt.) afforded maximum conversion of the plastics into liquid fuel oils.     

Effects of the types of zeolites on catalytic upgrading of pyrolysis wax oil

Because zeolites play an important role in an upgrading catalyst for heavy hydrocarbons in industrial refinery processes, the effects of the zeolite type on the upgrading of pyrolysis wax oil are investigated in this study. Raw pyrolysis wax oil was obtained from the pyrolysis of municipal plastic wastes in a commercial rotary kiln pyrolysis plant (Dongmyong RPF Co.). The catalystic experiments are performed for the three different types of commercial zeolites with different physicochemical properties in a continuous fixed bed reactor at 450 °C for 1 h as a MAT(micro-activity test) method: HZSM-5 (pure), zeolite Y (HY; pure or including 20% clay) and mordenite (HM; including 20% clay or alumina) catalysts. The highest conversion of pyrolysis wax oil into light hydrocarbons such as gas products and gasoline-range hydrocarbons is obtained for the HZSM-5 catalyst among them, and the composition of liquid products is found to become in the main aromatic components due to a shape selectivity. For the case of zeolite Y(HY), medium activity and the highest fraction of branched hydrocarbons with a high octane number, as well as a high fraction of aromatic products are shown. However, the mordenite (HM) with one-dimensional pore structure shows the lowest conversion of pyrolysis wax oil into light hydrocarbons and a very high fraction of paraffin product in the liquid product like the characteristics of raw pyrolysis wax oil.     

The effect of acidity behaviour of Y zeolites on the catalytic degradation of polyethylene

Thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses were used to investigate the effect of the acidity behaviour of Y zeolites on the catalytic degradation of polyethylene (PE). The acidity behaviour of these zeolites was modified by ion exchange treatments. Two Y zeolites with similar Si/Al atomic ratios were subjected to an ion exchange treatment using NaNO₃ for H-form (HY) and NH₄NO₃ for Na-form (NaY). The activity and the deactivation behaviour of the Y zeolites were determined in the samples by TGA measurements, using a polymer/catalyst ratio of 9:1. The sample residues obtained after an isothermic TGA, were analysed by DSC, in order to evaluate the crystallinity of each mixture. The HY zeolite, which has the strongest acidity, reduced the onset temperature resulting in more rapid degradation of the polymer. It is shown that the ion exchange treatment over Y zeolites enhances the selective catalytic degradation of polymer in detriment of the rapid deactivation.     

Synthesis of 3-(1-Cyclohexenyl)-2-butanone via Environmentally Friendly Catalysts

Introduction3- ( 1 - Cyclohexenyl) - 2 - butanone( CHB) is oneofthe importantchemicals and has a potential valuein perfume industry.Beak et al.[1] reported thatthe acylation of ethylidenecyclohexane( EDC) withzinc chloride as a catalystgave3- ( 1 - cyclohexenyl) -2 - butanone in a good yield,butthey have notmadea more detailed investigation.The use of such aconventional catalyst as zinc chloride leads to anumber of problems such as corrosion,unclean re-action products and the disposal of pot…     

Catalytic Acylation of Ethylidenecyclohexane over Zeolite Catalysts

Beak et al[1 ] reported that the acylation of ethylidenecyclohexane( EDC) using zincchloride as a catalyst gave 3 -( 1 -cyclohexenyl) -2 -butanone( CHB) in good yield.However,it is pity that they provided only little information about reaction conditions,and no information on comparison of activities of various catalysts. Itis well known thatconventional Zn Cl2 catalyst leads to a great number of environmental pollution,whichcould be mainly overcome by use of the solid catalysts as we have …     

抑制β沸石骨架脱铝的焙烧研究

研究了因焙烧过程升温速率对β沸石模板剂的热分解过程的影响,不同升温速率下Naβ沸石焙烧的尾气组成;还测定了Naβ沸石的TG-DTG谱,400℃下Naβ沸石的FIIR谱图,以及在不同温度下焙烧4 h后的XRD谱图及29Si、27Al的NMR结果.根据这些结果,提出了分段焙烧脱胺方法,使有机胺在260～420℃间的两个恒温段充分发生Hofmann降解反应,从而使分解产生的乙烯和水蒸气能够随空气流自然排出焙烧体系,可使焙烧过程中产生的热能得到分阶段逐步地释放,同时可避免高温下沸石骨架水热脱铝的负作用,得到骨架脱铝少、结晶度高的脱胺β沸石.     

由酸活化高岭土制备多级纳米孔HY分子筛及其表征

由酸活化的高岭土制备了多级纳米孔HY分子筛。通过改变老化时间和晶化时间可得到最大的多级因子(HF),此时外比表面积最大而微孔孔体积变化不大。运用X射线衍射(XRD)、X射线荧光光谱、N2吸附-脱附法和NH3程序升温脱附对所得样品进行了表征。老化2 d和晶化24 h所制的纳米孔HY分子筛样品的HF值最大。样品的酸性和结晶度也随着制备条件而变化。另外,适量NaCl的嵌入对提高对所制样品的HF值、酸性和结晶度起到重要作用。通过比较样品和常规HY分子筛的XRD峰强度算得样品的结晶度。结果表明,优化合成条件可得到广泛适用于工业化的分子筛制备路线。     

化学液相沉积法改性HY沸石及其对萘与叔丁醇择形烷基化反应的催化性能

采用化学液相沉积法,经异丁基三乙氧基硅烷修饰并用高温水蒸气处理得到了改性HY沸石.采用X射线衍射、低温N2吸附和脉冲式质量分析技术研究了改性样品骨架结构、比表面积、孔结构参数和吸附性质的变化,并考察了HY沸石及其改性后样品对萘与叔丁醇烷基化制备2,6-二叔丁基萘(2,6-DTBN)反应的催化性能.结果表明,改性后HY沸石的骨架结构基本不变,但比表面积增大,平均孔径缩小,孔口尺寸得到了一定调变.在改性后HY沸石催化剂上萘与叔丁醇烷基化反应活性下降,但催化剂择形性能明显提高,其2,6-DTBN/2,7-DTBN比可以达到6.62。     

Decomposition kinetic of carbonaceous materials used in a mold flux design

Mold fluxes develop important functions during steel continuous casting process. To obtain a free-defect product the melting rate of mold flux is an important property to be controlled. The melting rate depends on the reactivity of carbonaceous material added to these powders as carbon source. In this article, the decomposition kinetic of two carbonaceous materials added to mold flux: petroleum coke and synthetic graphite, was analyzed. By measuring mass loss at different heating rates the decomposition reaction was determined on both types of materials. Applying several kinetic models of non-isothermal decomposition, the average activation energy E = 48 kJ/mol to mold powder with 15 wt% coke and E = 67 kJ/mol to one with 15 wt% graphite was determined. A first order of reaction (n = 1) associated to the decomposition process was assumed to both types of materials. The lower activation energy presented by mold powder-15 wt% petroleum coke indicated a higher reactivity of this material. A higher level of variation of E and n values with decomposition degree and temperature observed in the powder with petroleum coke was associated to a less thermally stable material along with a more complex degradation process.     

Development of a rotating reactor for uniform solid treatments: Application to the steaming of HY zeolites

A laboratory scale rotating reactor designed for high temperature treatments of powders under controlled atmosphere is described. It was used for HY zeolite steamings. This rotating reactor allowed the lattice dealumination level to be governed with a good accuracy and to minimize concomitant amorphization. A series of well-defined steamed HY zeolites characterized by their lattice Si/Al ratio varying from 7.6 to 40 was obtained.     

NiY分子筛表面酸性影响其选择性吸附脱硫性能的机理研究

采用原位红外光谱技术,以噻吩、环己烯和苯为模型探针分子,分别考察单一烃分子在NiY分子筛上的吸附与反应行为以及噻吩与烯烃、芳烃间的竞争吸附和催化反应行为。单一探针分子吸附研究发现,NiY分子筛中与Ni物种相关的Lewis(L)酸位是噻吩的选择性吸附活性位;噻吩和环己烯在NiY分子筛中Brnsted(B)酸位上发生的质子化和低聚反应明显弱于HY分子筛。双探针分子竞争吸附研究发现,环己烯二聚体在NiY中强B酸位上的强化学吸附与噻吩存在显著的竞争吸附行为。另外,苯和噻吩在NiY上的竞争吸附现象在373K时明显减弱。由此,在选择性吸附脱硫过程中,减少吸附剂表面B酸中心可降低烯烃对噻吩的竞争吸附,另外适当提高吸附体系的温度可以有效避免芳烃对噻吩的竞争吸附。