Correlations between the Rayleigh ratio and the wavelength for toluene and benzene

The values of the Rayleigh ratio of two pure liquid, toluene and benzene, at various wavelengths have been collected from the literature, and a correlation between the Rayleigh ratio and the wavelength in the form of power law has been developed for each liquid and can be used to compute accurately the Rayleigh ratio at any wavelength between 420 and 700 nm. The Rayleigh ratio scales with the wavelength with a power of −4.17 and −4.38, respectively, for toluene and benzene, which deviate significantly from the Rayleigh law (−4.0). However, if the effect of the wavelength on their refractive indexes is accounted for, the power is reduced to −4.0 and −4.2 for toluene and benzene, respectively.     

Phase equilibria on five binary systems containing 1-butanethiol and 3-methylthiophene in hydrocarbons

Isothermal vapor–liquid equilibrium (VLE) of the following systems was measured with a recirculation still: 1-butanethiol + methylcyclopentane at 343.15 K, 1-butanethiol + 2,2,4-trimethylpentane at 368.15 K, 3-methylthiophene + toluene at 383.15 K, 3-methylthiophene + o-xylene at 383.15 K, and 3-methylthiophene + 1,2,4-trimethylbenzene at 383.15 K. 1-Butanethiol + methylcyclopentane and 1-butanethiol + 2,2,4-trimethylpentane systems exhibit positive deviation from Raoult's law, whereas systems containing 3-methylthiophene in aromatic hydrocarbons exhibit only slight positive deviation from Raoult's law. A maximum pressure azeotrope was found in the system 1-butanethiol + 2,2,4-trimethylpentane (x₁ = 0.548, P = 100.65 kPa, T = 368.15 K). The experimental results were correlated with the Wilson model and compared with original UNIFAC and COSMO-SAC predictive models. Raoult's law can be used to describe the behavior of 3-methylthiophene in aromatic hydrocarbons at the experimental conditions in this work. Liquid and vapor-phase composition were determined with gas chromatography. All measured data sets passed the thermodynamic consistency tests applied. The activity coefficients at infinite dilution are also presented.     

Cu_xCo_(1-x)/Al_2O_3/FeCrAl整体式催化剂上甲苯催化燃烧(英文)

以FeCrAl合金薄片为基底,Al2O3浆料为过渡胶体,不同摩尔比的Cu、Co为催化活性组分,制备了一系列CuxCo1-x/Al2O3/FeCrAl(x=0-1)新型整体式催化剂.采用X射线粉末衍射(XRD),扫描电子显微镜(SEM),X光电子能谱(XPS)和程序升温还原(TPR)等手段对催化剂的结构进行了表征.在微型固定床反应器上评价了催化剂的催化甲苯燃烧性能.研究结果表明:在所制备的整体式催化剂上,当Cu含量比较低时,形成了Cu-Co-O固溶体;当Cu含量比较高时,可以测得CuO的衍射峰.催化剂表面颗粒大小和形貌与Cu、Co摩尔比密切相关.在催化剂表面,Co以Co2+和Co3+价态存在,而Cu主要以Cu2+价态存在.催化剂中的Cu可以改善Co的氧化还原性,从而有利于催化剂活性的提高.在所制备的催化剂中,Cu0.5Co0.5/Al2O3/FeCrAl催化剂具有最好的活性,甲苯在374oC可以完全催化燃烧消除.     

Kinetic modeling of the benzyl + HO2 reaction

Benzyl is a resonantly stabilized radical that commonly occurs as an intermediate in the combustion of aromatic compounds. The bimolecular reaction of benzyl with HO₂ is important in the oxidation of toluene, especially at low to moderate temperatures, where unimolecular decomposition of the benzyl radical is slow. We show that the addition of HO₂ to the methylene site in benzyl produces a vibrationally excited benzylhydroperoxide adduct, with over 60 kcal mol⁻¹ (251 kJ mol⁻¹) of excess energy above the ground state. RRKM simulations are performed on the benzyl + HO₂ reaction, using thermochemical and kinetic parameters obtained from ab initio calculations, with variational transition state theory (VTST) for treatment of barrierless radical + radical reaction kinetics. Our results reveal that the benzyl + HO₂ reaction proceeds predominantly to the benzoxyl radical + OH at temperatures of around 800 K and above, with the production of stabilized benzylhydroperoxide molecules dominating at lower temperatures. The heat of formation of the benzyl radical is calculated as 52.5 kcal mol⁻¹ (219.7 kJ mol⁻¹) at the G3B3 level of theory, in relative agreement with other recent determinations of this value.     

A shock tube study of the auto-ignition of toluene/air mixtures at high pressures

The auto-ignition of toluene/air mixtures was studied in a shock tube at temperatures of 1021-1400 K, pressures of 10-61 atm, and equivalence ratios of Φ = 1.0, 0.5, and 0.25. Ignition times were measured using endwall OH∗ emission and sidewall piezoelectric pressure measurements. The measured pressure time-histories do not show significant pre-ignition energy release, in agreement with the rapid compression machine study of Mittal and Sung [G. Mittal, C.-J. Sung, Combust. Flame 150 (2007) 355-368] and disagreement with the shock tube study of Davidson et al. [D.F. Davidson, B.M. Gauthier, R.K. Hanson, Proc. Combust. Inst. 30 (2005) 1175-1182]. Kinetic modeling predictions from three detailed mechanisms are compared. Sensitivity analysis indicates that the reaction of toluene (C₆H₅CH₃) and the benzyl radical (C₆H₅CH₂) with molecular oxygen are important and examination of the rate coefficients for these reactions suggests that improved rate parameters for the multi-channel C₆H₅CH₂ + O₂ reaction may improve model predictions.     

Ni/MgO-Al2O3催化剂上高温焦油组分的催化转化

采用分步浸渍法制备了MgO-Al2O3负载的Ni基催化剂, 并运用N2吸附、载射线衍射(XRD)、透射电子显微镜(TEM)等手段进行表征. 该催化剂用于甲苯或萘为焦油模拟化合物的高温焦炉煤气(COG)的常压加氢裂解反应, 并考察了H2浓度、H2S对催化剂活性的影响. 结果表明: 催化剂还原后, 表面形成均匀分散、直径为8-14 nm的金属Ni纳米颗粒; 在较低的水碳摩尔比(nH2O/nC=0.28)时, 甲苯就能完全转化并选择性地加氢裂解形成CH4, 测试的时间内(480 min), 催化剂没有明显的失活和积炭现象, 显示出好的反应活性、稳定性和耐硫能力. 制得的Ni/MgO-Al2O3催化剂有望应用于较低水含量(10%-15%(φ, 体积分数))的高温焦炉煤气中焦油的直接转化.     

微波辐射法合成SAPO-5分子筛中硅铝比对产物结晶度和甲苯吸附性能的影响

采用硅溶胶作硅源, 用微波辐射法在酸性条件下(pH=4.5-5.0)合成了SAPO-5分子筛, 利用X射线衍射(XRD), 傅立叶变换红外光谱(FT-IR), 扫描电镜(SEM)和Brunauer-Emmett-Teller (BET)比表面积分析对样品的结晶度、形貌和比表面等进行表征, 考察了晶化原料硅铝比对分子筛结晶度和晶体颗粒长径比(c/a)的影响, 测定了分子筛对甲苯的吸附性能. 结果显示, 采用微波辐射法合成的SAPO-5分子筛, 在硅铝摩尔比为0.50附近生成产物的结晶度最好, 晶体颗粒的长径比最小(约为1.0). 尽管不同硅铝比条件下得到的样品比表面测定结果变化不大, 但对甲苯的吸附实验显示, 在硅铝比为0.50时样品的吸附速率和饱和吸附量均达到了最大值. 这与表征所得的结晶度和长径比的变化一致, 即结晶度好,长径比小的SAPO-5分子筛具有更好的甲苯吸附性能.     

FT-IR study of the photocatalytic degradation of gaseous toluene over UV-irradiated TiO2 microballs: enhanced performance by hydrothermal treatment in alkaline solution

In this study, photocatalysts of TiO₂ microballls were obtained via a hydrothermal treating of commercial P25 in alkaline solution, and then characterized with SEM, XRD, BET, DRS and surface photovoltage spectroscopy (SPS) techniques. The photovoltage response of the prepared TiO₂ microballs on spectrum features a quantum size effect brought about by the reduced grain size with respect to the precursor. The UV-assisted photodegradation of gaseous toluene over P25 and the prepared TiO₂ microballs was monitored by an in situ infrared technique. The results demonstrated that the prepared TiO₂ microballs in anatase form were more active than commercial P25 in photocatalytic oxidation of gaseous toluene. The promoted activity of the hydrothermal-treated TiO₂ is attributed to the increasing specific surface area and larger band gap induced by the reduced crystallite size.     

食品微晶蜡中苯及甲苯残留的顶空气相色谱法测定

应用带有顶空进样器气相色谱仪, 采用外标法定量, 分析食品微晶蜡中苯及甲苯残留量 ; 选择以食品用白油为母液制备一系列标准样品, 在选择的色谱条件下分析, 苯和甲苯含量分别在 10× 10-9～ 2 000× 10-9(w)间与峰面积呈现良好的线性关系, 检出限 (S/N=2)为 5× 10-9(w).