Thermal degradation of diethanolamine at stripper condition for CO2 capture: Product types and reaction mechanisms

Amine-based absorption/stripping is one of the promising technology for CO2 capture from natural and industrial gas streams.During the process,amines and CO2 undergo irreversible reactions to produce undesired compounds,which cause corrosion,foaming,increased viscosity and breakdown of equipment,ultimately contributing to the economic loss and environmental pollution.In this study,the thermal degradation of aqueous diethanolamine in the presence and absence of dissolved CO2 was investigated.The experiments were performed in stainless steel cylinders.The results show that thermal degradation in the absence of CO2 was a slow process;triethanolamine,and tris(2-aminoethyl)amine were only the degradation products identified in the mixture In addition,the rate of degradation was very low,only 3%degradation was observed after 4 weeks.But in the presence of CO2,sixteen degradation products were identified,nine of which were new degradation products reported for the first time in this study.The 3-(2-hydroxyethyl)-2-oxazolidinone,1,4-bis(2-hydroxyethyl)piperazine and triethanolamine were the most abundant degradation products.The remaining DEA concentration after 4 weeks was about 20%of the total amine concentration.The most probable degradation reactions and their mechanisms are also proposed.

Boosted Biodegradability and Tribological Properties of Mineral Base Oil by Methyl Diethanolamine Fatty Acid Esters

Methyl diethanolamine fatty acid esters, viz. methyl diethanolamine octanoate and methyl diethanolamine oleate,were prepared. Their impacts on the biodegradability and tribological properties of mineral base oil 400 SN were evaluated by a tester for fast evaluating the biodegradability of lubricants and by a four-ball tester, respectively. The results showed that methyl diethanolamine octanoate and methyl diethanolamine oleate both could markedly promote the biodegradation of the oil and improved its tribological properties. The improvement of biodegradability was attributed to the enhanced growth and quantity of microbes by methyl diethanolamine fatty acid esters. The worn surfaces were analyzed by a scanning electron microscope(SEM) equipped with an energy dispersive spectrometer(EDS) and an X-ray photoelectron spectroscope(XPS). The results indicated that the enhancement of friction-reducing and anti-wear properties of the mineral oil was attributed to the formation of complicated boundary lubrication films composed of species such as Fe_2O_3, Fe_3O_4 and organic nitrogen-containing compounds with a structure of –C-N-or R-NH_2.

SYNTHESIS AND CHARACTERIZATION OF NOVEL MULTIFUNCTIONAL HOST COMPOUNDS.1.β-CYCLODEXTRIN DERIVATIVE BEARING DIETHANOLAMINE MOIETY

A novel β-cyclodextrin(β-CD)derivative bearing diethanolamine moiety was synthesized by a convenient method with 63% yield,and the new host compound was characterized by (13)~C-NMR,FT-IR spectra etc,

Comprehensive evaluation and sensitivity analysis of regeneration energy for acid gas removal plant using single and activated-methyl diethanolamine solvents

The absorption of acid gas using reactive amines is among the most widely used types of capturing technologies.However,the absorption process requires intensive energy expenditure majorly in the solvent regeneration process.This study simultaneously evaluated the regeneration energy of MDEA and PZ/MDEA solvents in terms of heat of absorption,sensible heat,and vaporization heat.Aspen Hysys version 8.8 simulation tool is applied to model the full acid gas removal plant for the chemical absorption process.The new energy balance technique presents around the absorption and desorption columns to bring a new perspective of energy distribution in the capturing of acid gas plants.Sensitivity analysis of regeneration energy and its three contributors is performed at several operation parameters such as absorber and stripper pressures,lean amine circulation rate,solvent concentration,reflux ratio,and CO2 and H2 S concentrations.The results show that the heat of absorption of PZ/MDEA system is higher than that for MDEA system for the same operating conditions.The sensible heat is the main contributor in the required regeneration energy of MDEA solvent system.The simulation results have been validated against data taken from real plant and literature.The product specifications of our simulation corroborate with real plant data in an excellent approach;additionally,the profile temperature of the absorber and the stripper columns are in good agreement with literature.The overall results highlight the direction of the effects of each parameter on the heat of absorption,sensible heat,and vaporization heat.

Modeling the rate of corrosion of carbon steel using activated diethanolamine solutions for CO2 absorption

A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethanolamine(DEA)aqueous solutions.The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature,activator concentration,CO2 loading and pH.The study consists of two major models:Vapor–liquid Equilibrium(VLE)model and electrochemical corrosion model.The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution.The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal.An increase in concentration of activator,increases the rate of corrosion of carbon steel in mixtures of activated DEA.

Carbon dioxide induced degradation of diethanolamine during absorption and desorption processes

Alkanolamines are widely used in the purification of the sourgas sweetening process. During the sour gas absorption process, CO_2 significantly degrades the amine solvent and creates enormous problems for plant operation. In this work, CO_2 induced degradation of aqueous diethanolamine(DEA) solution was conducted in a 1.25 L jacketed glass reactor that functioned as an absorber and stripper at atmospheric conditions. Pure CO_2 was bubbled through the reactor until the solution became saturated. In this study, the concentrations of DEA used were in the range of concentrations between 2 mol·L^(-1) and 4 mol·L^(-1). In the degradation experiment, six generic cycles were conducted for each run. Each cycle was configured with the absorption and desorption of carbon dioxide at 55 ℃ and 100 ℃, respectively. Samples were collected after a predetermined experimental time and analyzed by ion chromatography(IC) to identify unknown ionic degradation products(DGPs). In the IC analysis, three different columns were used for anion, cation and ion exclusion systems, which are Metrosep A Supp 5150/4.0, Metrosep C Supp 4 150/4.0 and Metrosep Organic Acids, respectively. The major identified DGPs of D01 DEA2 M, D02 DEA3 M, and D03 DEA4 M are nitrite, acetate and ammonium. Phosphate product was found in the degraded amine samples which might be due to the contamination of water or chromatographic system.

Dissolution Properties of 2-(Dinitromethylene)-5-methyl-1,3-diazacyclopentane in Dimethyl Sulfoxide and N-Methyl Pyrrolidone

The molar enthalpies of dissolution for 2-（dinitromethylene）-5-methyl-1,3-diazacyclopentane（DNMDZ） in dimethyl sulfoxide（DMSO） and N-methyl pyrrolidone（NMP） were measured using an RD496-2000 Calvet microcalorimeter at 298.15 K under atmospheric pressure.Empirical formulae for the calculation of the molar enthalpies of dissolution（Δ diss H） were obtained from the experimental data of the dissolution processes of DNMDZ in DMSO or NMP.The relationships between the rate constant（k） and the molality（b） and between the reaction order（n） and the molality（b） were determined.The corresponding kinetic equations describing the two dissolution processes were dα/dt=10^-2.16（1-α） ^1.01 for the dissolution of DNMDZ in DMSO,and dα/dt=10^-2.02（1-α）^ 0.85 for the dissolution of DNMDZ in NMP,respectively.

Gamma-aminobutyric acid A receptor and N-methyl-D-aspartate receptor subunit expression in rat spiral ganglion neurons

BACKGROUND： Gamma-aminobutyric acid A （GABAA） and N-methyl-D-aspartate （NMDA） receptors are significant receptors in the central nervous system. An understanding of GABAA and NMDA receptor expression in spiral ganglion neurons （SGN） provides information for the functional role of these receptors in the auditory system. OBJECTIVE： To investigate mRNA expression of GABAA receptor （GABAAR） and NMDA receptor （NMDAR） subunits in the rat SGN. DESIGN, TIME AND SETTING： This in vitro, molecular biological study was performed at the Laboratory of Otolaryngology-Head and Neck Surgery, Guangxi Medical University, China from July 2007 to May 2008. MATERIALS： Reverse Transcriptase Kit and Taq DNA polymerase were purchased from Fermentas Burlington, ON, Canada; GABAAR and NMDAR primers were purchased from Shanghai Sangon, Shanghai, China. METHODS： SGN from 3-5 day postnatal Wistar rats was collected for primary cultures, mRNA expression of GABAAR and NMDAR subunits in the SGN was determined by reverse transcription polymerase chain reaction. MAIN OUTCOME MEASURES： Expression levels of GABAAR and NMDAR subunits were determined by quantitative analysis. RESULTS： GABAAR subunits （αl 6, β1 3, and y1 3） and NMDAR subunits （NR1, NR2A, NR2B, NR2C, NR2D, NR3A, and NR3B） were detected in the SGN. In α subunit genes of GABAAR, α1 and α3 expression was similar （P 〉 0.05） and greater than the other subunits. Of the β subunit genes, β1 subunit mRNA levels were greater than β2 and β3. Of the y subunit genes, y2 subunit mRNA levels were greater than y1 and y3. NR1 mRNA expression was the greatest of NMDAR subunits. CONCLUSION： GABAAR subunits （α1 6, β1-3, and y1-3） and NMDAR subunits （NR1, NR2A, NR2B, NR2C, NR2D, NR3A, and NR3B） were expressed in the rat SGN. Through comparison of GABAAR and NMDAR subunit expression, possible GABAAR combinations, as well as highly expressed subunit combinations, were estimated, which provided information for pharmacological and electrophysiological characteristics of GABAAR in the auditory system.

Synthesis and Structure Analysis of a Tripeptide Containing N-methyl Group Amino Acid

A convenient method of synthesizing a tripeptide-containing N-methyl group amino acid was developed using O-benzotriazole-N,N,N＇,N＇-tetramethyluronium-hexafluorophosphate as the condensing agent. The crystals of tripeptide had white needles belonging to the orthorhombic space group P2_12_12_1. The conformational preference for homochiral tripeptides with one N-methylated amide bond was also investigated. Crystal-structure analysis showed that homochiral tripeptides with an internal N-methylated amide bond preferred a trans-amide form, thereby giving the peptide β-fold characteristics. Intermolecular C-H···O and N-H···O hydrogen bonds linked the molecules into a one-dimensional chain and stabilized the structure.

RE-DISTRIBUTION OF THE N-METHYL GROUP IN GELSEMINE

The N_(b)-bromomethyl derivative (2) of gelsemine,a quaternary ammonium salt,was found to be recalcitrant toward Hofmann type alkaline degradation which has been successful in other cases.Instead,a re-distribution of the N-methyl group took place,giving rise to 3a,1,3b and 3c,in descending order of R_f values.

Identification of N-Methyl Bis(2-(Alkyloxy-Alkylphosphoryloxy)Ethyl) Amines by LC-HRMS/MS

N-Methyl bis(2-(alkyloxy-alkylphosphoryloxy)ethyl)amines, which are abbreviated as PNPs, are a series of new skeleton chemicals belonging to schedule 2.B.04 chemicals of Chemical Weapons Convention (CWC). PNPs are important markers of chemical warfare agents because they are structurally relative to both nerve agents and N-mustards. In this study, fragmentation pathways of the most characteristic fragment ions in Q-TOF mass spectrometry were proposed based on the information from accurate mass and secondary fragmentations of product ions scan experiments. Results indicated that the base ion in LC/HRMS was the quasi-molecular ion [M+H]+. In LC-HRMS/MS, it was [M+H-CnH2n+1P(O)(OH)CmH2m+1O]+ fragment ion which was formed by losing an alkyloxy alkylphosphoryloxy group from the quasi-molecular ion. The diagnostic ion m/z84.0814 was identified as [C5H10N]+, which was the group of (CH2=CH)2N+(H)CH3. PNPs have two protonated centers. One is on the N atom, the other is on the O atom (P=O). O-n-propyl PNPs generally exhibited two fragmentation pathways. Firstly, the quasi-molecular ion [M+H]+ lost a propoxy alkylphosphoryloxy group to produce [R1P(OH+)(O-n-C3H7)OCH2CH2N(CH3)CH=CH2]+, which could be fragmented further to produce [C5H10N]+ ion. Secondly, [R1P(OH+)(O-n-C3H7) OCH=CH2]+ ions were produced from [M+H]+ and fragmented further to produce the abundant ions [R1P(OH+)(OH)OCH =CH2]. However, O-isopropyl PNPs characteristically produced weak fragment ions [M+H-C3H6]+, which were presumably formed via loss of CH3CH=CH2 from [M+H]+. Other PNPs showed similar fragmentation pathways as O-n-propyl PNPs. On the summarization of the MS fragmentation pathways of PNPs, LC-HRMS/MS quantitative and qualitative methods were developed and applied to analyze N-Methyl bis(2-(butoxy-methylphosphoryloxy)ethyl]amine in high background organic samples. The analytical results had successfully supported the sample preparation for the 33rd official proficiency test of Organization for Prohibition of Chemical Weapons (OPCW).

化妆品中乙醇胺类的GC-MS分析

Gas chromatography-mass spectrometry (GC-MS) method has been developed for the simultaneous determination of monoethanolamine,diethanolamine,triethanolamine in cosmetics.The detected materials were extracted with ethanol by ultrasonic, then were analyzed by GC-FID and GC-MSD.The relative standard deviations (RSD) were 0.76%-3.43%,and recoveries were 85.8%-106.0%. The limit of detection was 0.05%.

甲基二乙醇胺双脂肪酸酯的合成与表征

研究了不同碳链长度的脂肪酸与N-甲基二乙醇胺的酯化反应。以月桂酸为原料,通过正交实验考察了反应温度、物料摩尔比、回流液温度、催化剂用量等因素对该酯化反应的影响,确定了较优的工艺条件为:反应温度200℃,n(月桂酸)∶n(N-甲基二乙醇胺)=1.8∶1.0,回流液温度70℃,催化剂用量(相对于反应原料的质量)0.3%。在该工艺条件下,酯化产物中甲基二乙醇胺双月桂酸酯(双酯胺)的质量分数可达98%以上。并对正辛酸、正癸酸、棕榈酸和硬脂酸与N-甲基二乙醇胺的酯化反应条件进行了优化,得到的产物中双酯胺的质量分数达98%以上。采用IR和1HNMR对双酯胺的结构进行了表征。

N-(2-氰乙基)二乙醇胺的合成

在无溶剂、无催化剂的条件下,以二乙醇胺和丙烯腈为原料,进行了合成N-(2-氰乙基)二乙醇胺的实验。由探索性实验确定了二乙醇胺仲胺基氰乙基化反应的主要影响因素,采用均匀设计并用SPSS与Matlab软件进行数据处理,确定了二乙醇胺仲胺基氰乙基化转化率与影响因素的回归方程。由回归方程确定了最优的反应条件:n(丙烯腈)∶n(二乙醇胺)=1.5,反应温度81℃,反应时间25min。在此条件下,二乙醇胺仲胺基氰乙基化转化率达99.9%。气-质联用仪与傅里叶变换红外光谱仪对产物进行表征的结果显示,产物为N-(2-氰乙基)二乙醇胺。

单烷氧取代苯基哌嗪类盐酸盐的合成

单烷氧基取代苯基哌嗪盐酸盐是合成苯基哌嗪类药物的重要中间体。以二乙醇胺为起始原料,经氯代反应制得β,β1 二氯代二乙基胺盐酸盐,然后与单烷氧基取代苯胺经环合反应合成5个目标化合物。其结构经红外光谱、核磁共振氢谱、质谱证实与目标化合物的结构一致。

二乙醇胺开环环氧树脂改性水性聚氨酯的合成及性能研究

采用二乙醇胺（DEOA）开环环氧树脂E-44制得端羟基环氧树脂（E-OH）,用E-OH合成一系列羟基环氧改性水性聚氨酯（EWPU）乳液,并研究了E-OH添加量对EWPU乳液的粒径及涂膜性能的影响.核磁氢谱（1H NMR）测定了E-OH的结构和开环率,傅里叶红外光谱（FT-IR）确定了水性聚氨酯（EWPU）的结构,激光粒度仪测定了EWPU乳液粒径,热重（TG）测定了EWPU的耐热性能.结果表明：随着E-OH添加量增大,EWPU预聚体黏度增大,乳液粒径增大,乳液稳定性下降.另外,随着E-OH添加量增大,EWPU胶膜吸水率、溶胀度、拉伸强度和断裂伸长率均出现先增加后降低的特点.EWPU胶膜力学强度最高可以达到26.69 MPa,断裂伸长率最高可以达到428.35％.综合分析实验数据得到E-OH在EWPU体系的最佳加入量为2.5％～3.5％.

二乙醇胺改性水性环氧树脂的制备研究

采用二乙醇胺对双酚A型环氧树脂(E-44)进行化学改性引入亲水性基团,制备出了稳定性良好的水性环氧树脂。通过研究二乙醇胺用量、反应温度对水性环氧树脂体系稳定性的影响,确定了最佳的原料配比;研究了水性环氧树脂的粒径分布。研究表明:随着二乙醇胺用量的增加,环氧树脂的亲水性增强。随着二乙醇胺与环氧基物质的量比的增大,水性环氧树脂的粒径变小,当二乙醇胺与环氧基的物质的量比为0.5∶1时,能够制备出性能稳定的环氧树脂水溶液。

二乙醇胺作添加剂Ru-Zn催化剂上苯选择加氢制环己烯

采用共沉淀法制备了Ru-Zn催化剂,考察了二乙醇胺的添加对Ru-Zn催化剂上苯选择加氢制环己烯性能的影响,并采用N2物理吸附、透射电镜、X射线衍射、X射线荧光、傅里叶变换红外和程序升温还原等手段对催化剂进行了表征.结果表明,二乙醇胺可以与浆液中ZnSO4反应生成(Zn(OH)2)3(ZnSO4)(H2O)3和硫酸二乙醇胺盐.随着二乙醇胺用量的增加,化学吸附在催化剂表面的(Zn(OH)2)3(ZnSO4)(H2O)3增多,它与硫酸二乙醇胺盐的协同作用提高了Ru-Zn(4.9%)催化剂上苯选择加氢生成环己烯的选择性.当二乙醇胺用量为0.3g时,(Zn(OH)2)3(ZnSO4)(H2O)3在Ru-Zn(4.9%)催化剂加氢后样品的表面高度分散,反应性能最佳,循环使用第3次时苯转化率为84.3%,环己烯选择性和收率分别达75.5%和63.6%;使用至第4次时,反应25min时苯转化率和环己烯选择性仍可达75%以上,环己烯收率为58%以上.

二乙醇胺脱氢反应动力学研究

二乙醇胺脱氢制亚氨基二乙酸是草甘膦生产中的关键步骤之一。为了研究固体催化剂Raney-Cu催化下二乙醇胺脱氢反应动力学,设计了单因素多水平实验方案,考察二乙醇胺初始浓度、催化剂用量、反应温度、反应压力等因素对反应的影响,在5L高压反应釜中测定了脱氢反应动力学数据。依据脱氢反应的基本原理,提出了二乙醇胺脱氢反应机理,建立了动力学模型:-dCAdt=VcatKAkCA(1+KACA)·VL。利用数值计算方法对实验数据进行非线性拟合,求得动力学参数:k=4.914×1010exp(-7.364×104/RT)mol·(Lcat)-1·h-1,KA=3.308×106exp(-5.450×104/RT)L·mol-1,并且验证其可靠性。结果表明,二乙醇胺脱氢反应由二乙醇胺在催化剂表面的反应所控制,得到的动力学方程在实验范围内是可靠的。

二乙醇胺基木质素非离子表面活性剂的制备及表征

依据酸沉淀法对碱木质素进行了分级,分级后pH值4～6的木质素与环氧氯丙烷、二乙醇胺反应,制备了木质素基非离子表面活性剂。通过红外光谱、含氮量的测定对产物的结构进行了表征,通过表面张力测定对产品的表面活性进行了分析。结果表明:木质素基非离子表面活性剂固含量为32.6%,含氮量为1.99%,红外光谱分析可确定在木质素上引入了环氧氯丙烷和二乙醇胺,水溶液表面张力降低到53.27 mN/m,表明二乙醇胺基木质素非离子表面活性剂(DLNS)具有良好的表面活性。另外通过与十二烷基磺酸钠(SDS)复配后浊度的测定,表明产品在SDS与DLNS的体积比为20∶3～20∶20范围与SDS复配,浊度较低,复配效果较好。