环烷酸乙二醇酯的HDO热力学分析

以选取的环烷酸乙二醇酯模型化合物为基础,利用热力学方法分析其加氢脱氧反应发生的可能性。由于环烷酸乙二醇酯及双环环烷烃的结构复杂,无法直接获得其热力学数据,故采用基团贡献法估算了环烷酸乙二醇酯及双环环烷烃在298.15 K标准状态下的生成焓、标准熵及热容随温度的变化关系,进而得到不同温度条件下环烷酸乙二醇酯HDO的焓变、吉布斯自由能变及平衡常数。计算结果表明,环烷酸乙二醇酯的HDO反应在指定条件下为放热反应并可自发进行,且其平衡常数很大,可视为不可逆反应。该方法也可用于其它酯类物质HDO的热力学分析。     

合成戊二酸二乙酯反应体系的热力学计算与分析

采用基团贡献法估算了反应体系中戊二酸和戊二酸二乙酯在298.15K标准状态下的生成焓和标准熵,并且估算了这两种物质的热容随温度变化的关系式,计算了不同温度条件下反应的吉布斯自由能和标准平衡常数。通过对该反应体系的热力学分析发现,当达到平衡时该反应几乎可以进行到底,从而验证了该反应在热力学上的可行性。     

己二酸二甲酯合成体系的热力学估算及分析

采用基团贡献法估算了反应体系中己二酸和已二酸二甲酯在298.15 K标准状态下的生成焓和标准熵,并且估算了这两种物质的比热容随温度变化的关系式,计算了不同温度条件下反应的焓变、吉布斯自由能变和标准平衡常数.通过对该反应体系的热力学分析发现,当达到平衡时该反应几乎可以进行到底,从而验证了该反应在热力学上的可行性.     

合成戊二酸二异辛酯反应体系的热力学计算与分析

采用基团贡献法估算了反应体系中戊二酸、异辛醇和戊二酸二异辛酯在298．15K标准状态下的生成焓和标准熵，并且估算了这3种物质的热容随温度变化的关系式，计算了不同温度条件下反应的吉布斯自由能和标准平衡常数。通过对该反应体系的热力学分析发现当达到平衡时该反应几乎可以进行到底，从而验证了该反应在热力学上的可行性。     

乙二醇与甲醇合成乙醇酸甲酯反应的热力学计算

采用Benson基团贡献法及基本的热力学公式,计算了以大宗化工产品乙二醇和甲醇为起始原料的主副反应的热力学函数,讨论了一步氧化酯化反应合成乙醇酸甲酯(MG)的可能性。热力学分析结果表明,主副反应都是平衡常数非常大的放热反应,在298～433K温度范围内,即使平衡常数Kp值随温度升高而有所减小,但是仍然很大,完全可以作为不可逆反应处理,因此,在热力学上都是非常有利的反应。为了提高主产物乙醇酸甲酯的收率,必须从反应动力学角度,研究强化主反应对副反应的速度竞争。     

费托合成油品加氢裂化异构化反应的热力学

利用Benson基团贡献法和ABWY法计算了费托合成油品的标准摩尔生成焓、标准熵及摩尔定压热容等基础数据,在298—750 K,对费托合成油品加氢裂化异构化反应体系的反应焓、吉布斯自由能以及平衡常数等热力学数据进行了计算;对体系中各反应的热力学可能性与生成顺序进行了判断以及各反应的热力平衡与限度进行了分析。结果表明:费托合成油品加氢裂化异构化反应是放热反应,低温时大部分反应在热力学上均能够自发的进行,且平衡常数均较大,能够进行到较高的程度;从热力学上看,升高温度不利于加氢裂化异构化反应的进行,适宜反应温度的选择应兼顾各种反应的进行;烯烃比烷烃更容易发生加氢裂化异构化反应;所获得的热力学数据可为费托合成油品加氢裂化异构化工艺研究、反应器开发以及新型催化剂研制等提供理论依据。     

枞酸与甲醇酯化反应的基团贡献法热力学分析

以枞酸为模型化合物、枞酸与甲醇的酯化为探针反应,采用基团贡献法对枞酸与甲醇酯化反应进行了热力学分析,计算了473～653 K、0.1～20 MPa反应体系的反应焓变、反应熵变、反应Gibbs自由能变以及反应平衡常数,探讨了温度与压力对酯化反应的影响。计算结果表明,反应的焓变为-46.31～-10.10 kJ·mol^-1,枞酸与甲醇的甲酯化反应为放热反应;反应Gibbs自由能变为-53.26～-25.49 kJ·mol^-1,反应为自发过程;标准压力下反应平衡常数为136.32～748.89,5～20 MPa下反应平衡常数为(1.1×10⁴)～(3.2×10⁴)。实验结果表明,在无催化剂条件下,超/亚临界甲醇与枞酸酯化反应的转化率分别为85.94%～94.89%、73.80%～81.20%,实验结果与基团贡献法热力学计算值相一致。     

催化合成乙酸乙酯的热力学计算与分析

以无水乙醇和冰乙酸为原料,以对甲苯磺酸催化剂催化合成乙酸乙酯。采用基团贡献法估算了反应体系中乙酸、乙醇和乙酸乙酯在298．15K标准状态下的生成焓和标准熵,并且估算了这3种物质的热容随温度变化的关系式,计算了不同温度条件下反应的吉布斯自由能和标准平衡常数。通过对该反应体系的热力学计算与分析,验证了该反应在热力学上的可行性。     

悬浮床加氢脱硫尾气水蒸气转化制氢热力学

以悬浮床加氢脱硫尾气为水蒸气转化制氢原料,采用改进的原子序数矩阵法构建了包含6个独立反应的化学反应体系。分别考察各个独立反应在不同反应温度下,标准摩尔反应焓、吉布斯自由能变及平衡常数的变化规律;借助HYSYS流程模拟软件中的GIBBS反应器,研究反应器出口温度、反应压力及水碳物质的量之比对产物平衡组成的影响。热力学研究结果表明：烷烃碳数越高,水蒸气转化反应的平衡常数、吉布斯自由能变和标准摩尔焓对温度的敏感性越高,达到相同转化效果所需的反应温度越低。HYSYS模拟确定该体系下最适宜的反应条件为反应器出口温度700℃、反应压力100kPa、水碳物质的量之比4。     

复合型多元醇酯合成反应的热力学分析及动力学研究

采用基团贡献法估算了己二酸、2-乙基己醇及三羟甲基丙烷酯化反应体系中各组分的基础热力学数据,探讨了温度对反应焓变、熵变、Gibbs自由能变和平衡常数的影响规律,热力学分析结果表明体系内各反应在所考察的温度范围内均为自发吸热过程,且升高温度有利于反应的正向进行;研究了氧化亚锡催化己二酸与2-乙基己醇以及己二酸单2-乙基己醇酯与三羟甲基丙烷的酯化反应动力学,实验结果表明两步反应均受动力学控制,且在一定的转化率区间内符合二级不可逆反应动力学特征,确定了两步反应的活化能和指前因子,建立的动力学模型能够较准确地描述复合型多元醇酯的合成过程。     

Electrochemical investigations of naphthenic acid corrosion for carbon steel and the inhibitive effect by some ethoxylated fatty acids

The electrochemical behavior and corrosion of carbon steel in various types of naphthenic acid solutions have been studied by using cyclic voltammetry technique. The data reveal that the anodic excursion spans of carbon steel in naphthenic acid solution are characterized by the occurrence of a well-defined anodic peak (peak A), followed by a passive region. The passivation may be related to the formation and precipitation of oxide film on the electrode surface. The data reveal that increasing naphthenic acid concentration enhances the anodic peak current density (I_PA) and shifts its peak potential towards more positive values. The corrosion rate of carbon steel depended critically on the naphthenic acid types. The rate of the corrosion process increased with increasing in molar mass of naphthenic acid, reaching a maximum value in the presence of CHPA acid (C₉), and then decreased.

Potentiodynamic polarization measurements indicated that ethoxylated fatty acid derivatives have a strong effect on the corrosion behavior of the carbon steel in naphthenic acid solutions. The inhibition efficiency of these compounds was found to vary with their nature and concentration. The order of effectiveness of the inhibitors was OL(EO)₈₀ > OL(EO)₄₀ > OL(EO)_20. The adsorption of ethoxylated fatty acid on the carbon steel surface in naphthenic acid solutions was found to obey Frumkin isotherm and kinetic-thermodynamic model.     

Influence of different sulfur compounds on corrosion due to naphthenic acid

The influence of different sulfur compounds on corrosion due to naphthenic acid was studied by means of the new method FeNCOR™. It was found that such influence occurs after the reduction of the given sulfur compound by the cathodic reaction of the overall process of naphthenic acid corrosion. When the reduction product is H₂S the formation of a potentially protective layer of FeS occurs, whereas when the reduction product is H₂O, coming from the reduction of sulfoxides, the naphthenic acid corrosion is enhanced. These findings help to understand crude oil corrosivity behavior and serve as a warning for blending.     

环烷酸的分析与腐蚀预测方法

以选择高效缓蚀剂,从而最终有效解决原油加工设备的一系列腐蚀问题为目的。介绍了环烷酸的结构及性质,综述原油中环烷酸的分析方法与腐蚀预测方法。通过对有关环烷酸腐蚀预测方法和环烷酸的分析方法的有关报道进行分析得出:以环烷酸腐蚀介质中的高压釜失重实验为基础的金属挂片法是目前较好的预测方法,可提供与环烷酸腐蚀最为直接的参考数据。同时认为应用多种分析手段(如质谱结合色谱、紫外、红外、核磁共振等一些分析手段)来研究环烷酸的组成是较为理想的方法。     

Removal of naphthenic acids from a vacuum fraction oil with an ammonia solution of ethylene glycol

A new method to remove and purify the naphthenic acids in heavy fractions of petroleum is studied in this paper. An ammonia solution of ethylene glycol was used as the acid removal reagent by mixing with the petroleum fraction and then allowing the two phases to separate, with the naphthenic acids being extracted from petroleum fractions. The naphthenic acids were recovered by heating the ammonia solution containing naphthenic acids to release NH₃ and decompose the naphthenic acid ammonia salt. Petroleum ether was used to purify the naphthenic acids by extracting the neutral oils from the acid removal reagent. Data indicated that the optimal extraction temperature was in the range of 50–60 °C and the optimal NH₃ content in ethylene glycol was 3–5%. The contact time should be more than 10 min with the reagent/oil ratio being more than 0.3 (wt/wt). Acid removal can be greater than 85%. After purification by petroleum ether, the purity of naphthenic acids can be greater than 90%.     

High-efficiency separation and extraction of naphthenic acid from high acid oils using imidazolium carbonate ionic liquids

N-alkyl imidazolium carbonate ionic liquids were employed to separate and recover naphthenic acid from model oils.The effects of the cationic and anionic structures of ionic liquids and operating condi-tions on the deacidification performance were investigated.The deacidification performance of tradi-tional organic solvents was also investigated for comparison.The results indicated that the naphthenic acid could be completely removed from the model oil with a small mass ratio of ionic liquid to oil.The extracted naphthenic acid was regenerated with a recovery of up to 92％.In addition,imidazolium carbonate ionic liquids could be successfully regenerated and recycled.The mechanism of interaction between imidazole ionic liquids and the naphthenic acid molecules were explained by Gauss calculation.     

环烷酸对炼油设备的腐蚀与防护

对主要炼油设备重点部位的腐蚀现象进行了分析,确认环烷酸是造成设备腐蚀的主要原因。通过对环烷酸腐蚀影响因素的分析,提出了环烷酸腐蚀的控制措施。     

Extraction of yttrium using naphthenic acid with different acid numbers

Naphthenic acid with acid number of 100–200 mg KOH/g could be used to extract yttrium in the system of 20% naphthenic acid + 20% n-butanol + 60% n-hexane. A transparent and uniform phase was formed during saponification but did not influence the extraction process. n-Butanol and n-hexane could shorten phase separation time and lessen emulsification. Excess naphthenic acid and ammonia, and non-naphthenic acid substances contributed to emulsification and difficulty in phase separation, which were especially serious in system of 20% naphthenic acid + 20% 2-octanol + 60% kerosene. Naphthenic acid with acid number <100 mg KOH/g was unsuitable for extraction in either system. Extraction percentages were 99% and 46% when being saponified by 12.7 and 6.3 mol/L ammonia, respectively.     

Stability of water/toluene interfaces saturated with adsorbed naphthenic acids—A molecular dynamics study

Stability of water/toluene interfaces saturated with adsorbed naphthenic acids with various sizes at room temperature was studied by molecular dynamics simulation. In direct comparison with our recent results on similar systems involving n-heptane as the oil phase, it has been found that toluene significantly enhances the stability of the water/oil interface, as suggested by the considerably reduced diffusion coefficients of the interface-bound naphthenic acids. The oil phase dependence may be rationalized in terms of the oil-naphthenic acid interactions, both electronically and sterically, and the intermolecular interactions between the molecules in the oil phase. Consistent with our previous studies, mobility of naphthenic acid has been found to be dependent on its size, with naphthenic acid featuring a longer carbon chain in between the carboxylic and cycloaliphatic groups showing lower mobility, leading to a more stable interface. However, such size dependence is much more pronounced for the water/toluene than the water/n-heptane interface. This may be understood in terms of the structural influence of toluene on the compactness of the liquid crystalline mesophase formed by naphthenic acids adsorbed at the interface.     

环烷基咪唑啉的合成及其缓蚀杀菌性能研究

以环烷酸与二乙烯三胺等有机多胺为原料,合成出不同配比的环烷基咪唑啉产品,研究了其缓蚀杀菌性能,结果显示,环烷基咪唑啉产品具有良好的缓蚀、杀菌效果,适宜于作炼油缓蚀剂、油剂杀菌防菌剂等。