Ethanolysis of soybean oil into biodiesel: process optimization via central composite design

A process for production of ethyl ester for use as biodiesel has been studied. The sodium hydroxide catalyzed transesterification of soybean oil with ethanol was carried out at different molar ratio of alcohol to oil, reaction temperature and catalyst amount for a constant agitation in two hours of reaction time. Central composite design and response surface methodology were used to determine optimum condition for producing biodiesel. It was found that ethanol to oil ratio and catalyst concentration have a positive influence on ester conversion as well as interaction effects between the three factors considered. An empirical model obtained was able to predict conversion as a function of ethanol to oil molar ratio, reaction temperature and catalyst concentration adequately. Optimum condition for soybean ethyl ester production was found to be moderate ethanol to oil ratio (10.5: l), mild temperature range (70°C) and high catalyst concentrations (l.0%wt), with corresponding ester conversion of 93.0%.     

High throughput operando studies using Fourier transform infrared imaging and Raman spectroscopy

A prototype high throughput operando (HTO) reactor designed and built for catalyst screening and characterization combines Fourier transform infrared (FT-IR) imaging and Raman spectroscopy in operando conditions. Using a focal plane array detector (HgCdTe focal plane array, 128x128 pixels, and 1610 Hz frame rate) for the FT-IR imaging system, the catalyst activity and selectivity of all parallel reaction channels can be simultaneously followed. Each image data set possesses 16 384 IR spectra with a spectral range of 800-4000 cm(-1) and with an 8 cm(-1) resolution. Depending on the signal-to-noise ratio, 2-20 s are needed to generate a full image of all reaction channels for a data set. Results on reactant conversion and product selectivity are obtained from FT-IR spectral analysis. Six novel Raman probes, one for each reaction channel, were specially designed and house built at Pacific Northwest National Laboratory, to simultaneously collect Raman spectra of the catalysts and possible reaction intermediates on the catalyst surface under operando conditions. As a model system, methanol partial oxidation reaction on silica-supported molybdenum oxide (MoO3SiO2) catalysts has been studied under different reaction conditions to demonstrate the performance of the HTO reactor.     

Dynamic simulation and nonlinear control of a rigorous batch reactive distillation

This work deals with the dynamics and control of a high-purity batch distillation column with chemical reaction. A heterogeneous esterification reaction between the acetic acid and butanol takes place to produce butyl acetate. The process model is formulated considering variable liquid holdup, UNIQUAC model for thermodynamic property predictions, nonlinear Francis weir formula for tray hydraulics, pseudohomogeneous model to represent the reaction kinetics and rigorous energy balance. A structured and simple iterative approach is devised to compute the vapor flows with the fast convergence, under the rigorous energy balance.The representative column is treated with a distillate policy based on which, the lightest product, water is removed as distillate at the starting of production phase. As a consequence, the column gets progressively richer with the main product, butyl acetate. In addition, almost complete conversion of the limiting reactant is achieved. In order to maintain the product purity at the top, a nonlinear generic model controller (GMC) in two different forms has been proposed. Finally, a comparative closed-loop performance is addressed. It is shown that the control scheme, along with the effective distillate strategy, leads to almost complete conversion of ingredients and high-purity products.     

粉末X射线衍射法鉴定天然气绝热转化制氢催化剂中晶体化合物

首次详细报道采用粉末X射线衍射法(PXRD)鉴定天然气低温绝热、蒸汽转化制氢催化剂(简称天然气绝热转化制氢催化剂)中晶体化合物。其主要物相鉴定结果为:尖晶石(MgAl_2O_4)、绿镍矿(NiO)、刚玉(α-Al_2O_3)。其中还含有铝酸锶(SrAl_(12)O_(19))。PXRD鉴定数据能够满足天然气绝热转化制氢催化剂研发的要求。     

High-throughput reactor system with individual temperature control for the investigation of monolith catalysts

A high-throughput parallel reactor system has been designed and constructed to improve the reliability of results from large diameter catalysts such as monoliths. The system, which is expandable, consists of eight quartz reactors, 23.5 mm in diameter. The eight reactors were designed with separate K type thermocouples and radiant heaters, allowing for the independent measurement and control of each reactor temperature. This design gives steady state temperature distributions over the eight reactors within 0.5 degrees C of a common setpoint from 50 to 700 degrees C. Analysis of the effluent from these reactors is performed using rapid-scan Fourier transform infrared (FTIR) spectroscopic imaging. The integration of this technique to the reactor system allows a chemically specific, truly parallel analysis of the reactor effluents with a time resolution of approximately 8 s. The capabilities of this system were demonstrated via investigation of catalyst preparation conditions on the direct epoxidation of ethylene, i.e., on the ethylene conversion and the ethylene oxide selectivity. The ethylene, ethylene oxide, and carbon dioxide concentrations were calibrated based on spectra from FTIR imaging using univariate and multivariate chemometric techniques. The results from this analysis showed that the calcination conditions significantly affect the ethylene conversion, with a threefold increase in the conversion when the catalyst was calcined for 3 h versus 12 h at 400 degrees C.     

四丁基碘化胺相转移催化法合成苯甲酸苄酯

主要研究了由苯甲酸钠和氯化苄为原料,采用相转移催化法合成苯甲酸苄酯的酯化反应。通过几种催化剂的考察,筛选出合成苯甲酸苄酯反应性能较好的一种季铵盐类相转移催化剂为四丁基碘化铵((C4H9)4NI),同时考察了它的最佳反应条件。研究结果表明:在反应温度为110℃,苯甲酸钠与氯化苄摩尔比为1:1.3,反应时间2.5h～3.0h,催化剂用量为苯甲酸钠摩尔量的6%左右,pH为5～6的弱酸性时为最佳反应条件。四丁基碘化铵是季铵盐类相转移催化合成苯甲酸苄酯的较为理想的一种催化剂。     

Quantitative analysis of transient surface reactions on planar catalyst with time-resolved time-of-flight mass spectrometry

A procedure for the quantitative analysis of transient surface catalytic reactions in millisecond time resolution has been studied constructing a specially designed apparatus employing (1) pulsed-gas valves for the injection of reactant molecules onto catalysts and (2) a time-of-flight mass spectrometer (TOF-MS) to detect every reaction product simultaneously. For a better understanding of the catalytic activity and selectivity for products quantitatively, a procedure for measuring an amount of reactant molecules injected onto catalyst surface and calibrating the intensity of mass signal were proposed and implemented. We tested the applicability of this procedure for the quantitative analysis of products of NO+H(2) reaction on Pt-Al(2)O(3) catalysts (a planar catalyst: Pt-Al(2)O(3)Si substrates inserted into a micro-tube-reactor with SiC balls). Although the surface area of the planar catalyst was very small, the mass signal intensities of the reaction products were found to be sufficient for the above procedure. We measured the fragmentation patterns and the inherent sensitivity factors in the TOF-MS using the mixture of the internal standard gas Ar and the N-containing gases. The relative sensitivity factors for NH(3), N(2), NO, and N(2)O and the relative intensities of fragment peaks to the molecular ion peak of H(2)O and N(2)O were estimated. The procedure constructed here has enabled us to analyze the transient consecutive secondary catalytic reactions as well as primary reactions based on the formation rate of product molecules per millisecond instead of the mass signal intensities of the reaction products.     

Development behavior of vaporizing sprays from a high-pressure swirl injector using exciplex fluorescence method

The effects of ambient conditions on vaporizing sprays from a high-pressure swirl injector were investigated by an exciplex fluorescence method. Dopants used were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to examine the behavior of liquid and vapor phases inside of vaporizing sprays, ambient temperatures and pressures similar to engine atmospheres were set. It was found that the ambient pressure had a significant effect on the axial growth of spray, while ambient temperature had a great influence on the radial growth. The spatial distribution of vapor phase at temperatures above 473K became wider than that of liquid phase after half of injection duration, From the analysis of the area ratio for each phase, the middle part (region II) in the divided region was the region which liquid and vapor phases intersect. For liquid phase, fluorescence-intensity ratio was greatly changed at lms after the start of injection. However, the ratio of vapor phase was nearly uniform in each divided region throughout the injection.     

Application of microwave spectroscopy to chemical analysis.

Traditional analytical techniques have been sucessfully employed on a great variety of systems for identifying stable reaction products as well as for purity analysis and reaction efficiency. However, most analytical techniques generally can only be applied to "well-behaved" chemical systems. Since gas phase reaction products do not always follow the "well-behaved" guideline, an alternate analytical tool, such as microwave spectroscopy, could prove beneficial for analyzing such systems and may well provide some new routes to synthetic chemistry. A general review of the present state-of-the-art for applications of microwave techniques to analytical studies will be presented. An attempt will be made to describe the limitations and advantages of microwave spectroscopy for probing chemical systems for product identification and for optimization of the efficiency of gas phase chemical reactions. As an illustration, some recent results obtained in our laboratory on the complex pyrolytic decomposition reactions of ethylamine will be described. Further examples of possible applications will be taken from typical industrial processes that employ vapor phase chemical synthesis techniques.     

气相色谱-质谱联用法检测保健品中8种安眠镇静类药物

采用气相色谱-质谱联用法同时检测保健品中的地西泮,咪达唑仑,硝基安定,唑吡坦,氯硝安定,艾司唑仑,阿普唑仑和佐匹克隆。用叔丁基甲醚提取,甲基睾酮作为内标,HP-1MS色谱柱(17 m ×0.2 mm×0.11 mm )分离,程序升温,质谱检测。该方法的检测限和回收率均满足保健品日常检测的要求,前处理简单、快速、可靠。     

试验条件对氧化锌纳米材料形貌的影响

以氧化锌粉为原料,采用化学气相沉积的方法,通过控制沉积温度、生长压强和生长时间等试验条件,获得不同形貌的氧化锌纳米材料。利用扫描电镜和X射线衍射等仪器进行表征,并对氧化锌纳米材料的生长机制进行进一步探讨。     

The ideality of polydisperse perfluoropolyether lubricants with application to physical vapor deposition

We have used thermogravimetric analysis (TGA) to measure the evaporation rate as a function of temperature and molecular weight for an alcohol-derivatized perfluoropolyether (PFPE), Fomblin Zdol. We show that the bulk evaporation rate of a polydisperse Zdol solution during temperature ramp TGA can be numerically simulated by combining molecular weight dependent Arrhenius parameters, the initial molecular weight distribution as measured by size exclusion chromatography, and Raoult’s law of vapor pressures. The simulation is shown to be in good agreement with experiment for both a low molecular weight polydisperse Zdol, and for a mixture of the low molecular weight Zdol with a heavier Zdol fraction. Mixtures of Zdol with non-functionalized Z lubricants are shown qualitatively to deviate substantially from ideality. In the disc drive industry, physical vapor deposition (PVD) is receiving renewed interest as an alternative method of applying the PFPE lubricants commonly employed as topical coatings on thin film magnetic media. In a process involving vaporization of a polydisperse liquid phase lubricant, quantitative prediction of deposition rates and vapor phase molecular weight distributions will in general only be possible with accurate knowledge of liquid phase distributions, component evaporation rates, and the ideality of the solution. This revised version was published online in August 2006 with corrections to the Cover Date.     

A study on the behavior characteristics of diesel spray by using a high pressure injection system with common rail apparatus

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 22 MPa to 112 MPa using a high pressure injection system (ECD-U2). Also, we conducted simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.     

Optimal preparation conditions for some diester based synthetic lubricants

In this paper, work is reported on the esteriflcation of various materials, where di-2-ethythexyl esters of succinic, adipic, azelaic and sebacic acid were prepared. Water produced by the reaction was separated continuously and the reaction progress was followed up by measurement of the acid content. Factors affecting the esterification were studied and the optimal conditions for conversion of about 92% to 95% (by weight) were found to be: temperature — 179°C; molar ratio of add to alcohol — 1:2.4; catalyst concentration — 3% (by weight) based on acid; agitation rate — 350 r/min.     

1‐Pyrenemethanol,a Useful Fluorometric Reagent for the Detection and Determination of Carboxylic Acids in Atmospheric Samples

Abstract

A rapid fluorometric procedure for the selective and sensitive determination of carboxylic acids, based on pre‐column derivatization using 1‐pyrenemethanol, was optimized and applied to atmospheric sampling. The optimum conditions for derivatization were determined to be: reaction solvent–dichloromethane, temperature ?44°C, reaction time ?30 min, and reagent/total acid ratio ?15. Separation of the derivatives of acids up to twenty carbons by reversed‐phase (C₈) chromatography was achieved in 25 min using a water/acetonitrile gradient with a limit of detection for the derivatives of 20 pg for a 20 µL injection. A scanning detector with good spectral resolution allows qualitative identification of the components in complex samples. When used in atmospheric analysis, the recoveries of carboxylic acids from spiked samples were >80% with repeatabilities below 10% RSD. Low molecular weight acids were encountered predominantly in the vapor phase (0.20 to 92 ng/m³), whereas higher molecular weight acids were found mostly in particulate form (0.15–129 ng/m³).     

A study on the behavior of evaporating diesel spray using LIEF measurement and kiva code

The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated. The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore, this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the experimental parameter, is changed from 400 bar to 800 bar by using a common rail injection system. Also, we conducted simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with experimental results.     

催化剂反应罐温度控制系统

针对催化剂反应罐温度控制的需要，研制了催化剂反应罐温度计算机控制系统。采用PC机、RS232／422通讯接口、SR53／SR73智能仪表，实现了对催化剂反应罐温度的实时检测、实时控制，为催化剂反应罐温度控制提供了一种有效、方便的自动化手段。     

An investigation of reaction progression through the catalyst bed in methanol autothermal reformation

This study investigates autothermal reforming of fuel cell-grade methanol as a method for producing hydrogen for transportation applications. A previous study on the effects of oxygen-to-carbon ratio on ATR reactor performance showed that the optimum of O₂/CH₃OH=0.30 found in the experimental tests is 30% higher than the theoretical optimum of 0.23. In this study, the influence of catalyst bed length is investigated to give insight into the reaction progression through the catalyst bed in methanol autothermal reformation. The effect of reaction progression through the catalyst bed is experimentally investigated in relation to reactor output parameters of fuel conversion, temperature profile, and reactor efficiency. The results from this study serve as a baseline for future research of autothermal reforming of hydrocarbon fuels as a method for producing hydrogen.     

A resistive pyrolytic radical source for gas-surface reaction studies

We describe a thermal gas cracker designed to produce low fluxes of gas-phase radicals for use in radical-surface reaction studies. A resistively heated thin piece of highly oriented pyrolytic graphite is used as the pyrolysis filament, with the major advantage that this material remains inert at high temperatures. The instrument is built within an existing titanium sublimation pump, which simplifies construction and allows for self-pumping of the radical source. Thermal generation of Cl atoms from Cl(2) was chosen to test the effectiveness of the instrument. (35)Cl and (37)Cl were generated with a concomitant decrease in parent (70)Cl(2) and (72)Cl(2) species, as monitored by a residual gas analyzer. The cracking fraction of Cl(2) as a function of cell temperature is reported, with nearly full conversion achieved at high temperature.     

超高效液相色谱-串联质谱法快速测定洗发育发类化妆品中6种违禁药物

建立了超高效液相色谱-串联质谱（UPLC-MS/MS）分析方法同时检测洗发育发类化妆品中6种违禁药物。样品经甲醇超声萃取,用 Waters Acquity UPLC BEH C18色谱柱（100 mm×2.1 mm×1.7 μm）分离,以甲醇和0.1%甲酸-水溶液为流动相梯度洗脱,在电喷雾正离子模式下,采用多反应监测（MRM）模式进行定性和定量分析。结果表明,6种药物在各自线性范围内的线性关系良好,相关系数（R²）均大于0.997,检出限为0.9~13.3 μg/kg,3个加标水平下的回收率在84.0%~94.7%之间,RSD在1.3%~5.6%（n=6）之间。该方法准确、简便,可用于洗发育发类化妆品中违禁药物的快速检测。