氮化物对NiW/Al2O3上DBT和4,6-DMDBT加氢脱硫反应活性的影响

以碱性氮化物喹啉和非碱性氮化物吲哚为杂质,考察DBT和4,6-DMDBT在NiW/Al2O3上的加氢脱硫活性和选择性。结果表明,氮化物对DBT和4,6-DMDBT的加氢脱硫反应存在截然不同的作用结果。氮化物存在条件下,DBT的加氢脱硫反应通过直接脱硫路线活性的提高得到改善,而4,6-DMDBT的加氢脱硫反应由于氮化物的存在受到抑制。这主要是因为氮化物在加氢活性位上的吸附抑制了硫化物在加氢活性位上的吸附,从而抑制了加氢路线的进行。但氮化物使催化剂表面结构重排使硫化物氢解活性提高成为可能,此时硫化物的分子大小和分子结构起到了决定性作用。DBT由于分子体积小、通过S原子与氢解活性位接触容易而使氢解活性提高,4,6-DMDBT由于分子体积大和4、6位的位阻效应以及氮化物的拥塞效应使氢解活性随N含量的升高而减小。     

氮化物对柴油深度和超深度加氢脱硫的影响Ⅰ.氮化物含量的影响

氮化物和硫化物同时存在于柴油之中。采用硅胶脱除原料中氮化物，得到硫含量相同而氮含量不同的4种柴油原料。为了考察氮化物对加氢脱硫（HDS）的影响，在反应温度350℃、氢分压4．8MPa、液时空速2．0h^-1和氢／油体积比300的条件下，采用工业化的NiW／Al2O3催化剂在小型固定床实验装置上对该4种柴油原料进行加氢脱硫实验。结果表明，在真实油品的复杂体系中，氮化物对加氢脱硫反应有明显的抑制作用，加氢脱硫反应速率随着原料中氮含量的增加而降低。分子模拟计算结果表明，氮化物与硫化物在催化剂活性位上发生竞争吸附，氮化物的吸附能力较强，抑制了加氢脱硫反应。     

柴油超深度加氢脱硫机理及氮化物影响的研究进展

介绍了柴油超深度加氢脱硫（HDS）机理及氮化物对其的影响。介绍了硫化物存在形式、相对反应速率及其HDS反应路径。结果表明：非噻吩类硫化物HDS活性较高,在加氢催化剂活性中心上直接氢解生成相应的烃和H2S;催化剂的酸性在加氢精制工艺中对裂化反应有促进作用,必须考虑到脱硫率和催化剂寿命的最优化选择;碱性氮化物比非碱性氮化物对HDS的抑制作用强,不同催化剂的抗氮化物毒化能力不同,氮化物对HDS的两种路径影响不同,对加氢（HYD）路径的抑制作用强于直接氢解（DDS）路径;柴油馏分超深度HDS机理及氮化物对其抑制机理的研究,可以指导高活性、抗抑制剂催化剂的开发,从而缓和工艺条件,延长催化剂寿命。     

柴油加氢脱硫绝热反应动力学模型

研究了NiMo型催化剂在柴油加氢反应过程中的动力学规律,综合考虑硫化氢、氮化物和芳烃的抑制作用,建立了三集总加氢脱硫反应动力学模型。通过对反应过程中放热和温升的估算,建立了柴油绝热加氢脱硫反应动力学模型。根据模型计算了等温和绝热环境中物流性质沿反应器轴向的变化规律。结果显示,二者的变化规律存在明显差异,达到相同脱硫深度时,绝热条件中硫化物和氮化物前期脱除速率慢于等温条件。另外,通过模型详细描述了绝热条件各集总硫化物、氮化物和芳烃含量沿反应器轴向的变化规律,获得了各集总在反应器不同位置硫化物、氮化物和芳烃含量的定量数据,结果显示,硫化物、氮化物和芳烃含量各集总的变化趋势均不相同。     

氮对催化裂化汽油中烯烃加氢饱和反应的影响

 采用硅胶吸附脱除原料中氮化物，得到氮含量不同而硫含量及烃类组成基本相同的4种催化裂化汽油原料。为了考察氮化物对催化裂化汽油选择性加氢脱硫过程烯烃加氢饱和反应(HYDO)的影响，在反应温度285 ℃、氢分压1.6 MPa、体积空速4.0 h-1及氢油体积比400的条件下，采用Co-Mo/Al2O3催化剂在中型固定床试验装置上进行了4种催化裂化汽油原料选择性加氢脱硫试验。结果表明，在催化裂化汽油选择性加氢脱硫过程中，氮化物对HYDO有明显的抑制作用；对直链烯烃和环烯烃加氢饱和反应抑制作用明显，但对支链烯烃加氢饱和反应抑制作用较小。硫含量和烃类组成相同的原料，烯烃饱和率相同时，氮含量较高的原料加氢产物研究法辛烷值比氮含量较低的原料加氢产物研究法辛烷值损失小。     

硫化物对裂解C_9一段加氢Ni/Al_2O_3催化剂加氢活性的影响

在固定床反应装置上考察了噻吩、二丙基硫醚和正丁硫醇对裂解C_9一段加氢Ni/Al_2O_3催化剂加氢活性的影响,采用XPS和XRD对催化剂进行了表征,分析了硫化物影响Ni/Al_2O_3催化剂加氢活性的机理。实验结果表明,在考察的反应条件下,噻吩和二丙基硫醚影响Ni/Al_2O_3催化剂加氢活性的原因是硫化物吸附在催化剂的活性中心,占据了加氢活性位,降低了反应分子与催化剂活性位的接触机会;正丁硫醇影响Ni/Al_2O_3催化剂加氢活性的原因是活性金属Ni与正丁硫醇分解生成的H_2S反应生成硫化镍,催化剂的加氢活性相变为硫化态,同时正丁硫醇和生成的硫醚类硫化物吸附在催化剂的活性中心,占据了加氢活性位,使催化剂活性降低。     

二苯并噻吩和4-甲基二苯并噻吩在Mo和CoMo/γ-Al2O3催化剂上加氢脱硫的反应机理

研究了二苯并噻吩(DBT)和4-甲基二苯并噻吩(4-MDBT)在Mo／γ-Al2O3和CoMo／γ-Al2O3上加氢脱硫反应的产物分布及其可能的反应网络，并通过反应压力和温度对产物分布的影响，揭示了加氢脱硫反应的可能机理。DBT在Mo／γ-Al2O3上的加氢脱硫反应主要通过直接氢解路径和加氢路径进行，两种途径的作用相近；在CoMo／γ-Al2O3催化剂上的加氢脱硫主要通过直接氢解路径进行。4-MDBT在Mo／γ-Al2O3和CoMo／γ-Al2O3上的加氢脱硫反应主要通过加氢路径进行。Co的加入有助于提高Mo／γ-Al2O3催化剂的加氢脱硫活性，尤其是直接氢解脱硫活性。4-MDBT加氢脱硫反应中加氢路径的相对作用显著大于DBT加氢脱硫反应的加氢路径，间接证明4-MDBT的加氢脱硫过程存在对“端连吸附”的空间位阻。4-MDBT分子中甲基的供电子作用有利于促进苯环的加氢反应，从而有助于缩小与DBT分子间加氢脱硫活性的差别。在DBT和4-MDBT加氢脱硫反应中，反应压力和温度对加氢路径的影响大于对氢解路径的影响。     

4,6-二甲基二苯并噻吩在Co-Mo/γ-Al2O3上加氢脱硫反应机理的研究

研究了4,6-二甲基二苯并噻吩(4,6-DMDBT)在Co-Mo/γ-Al2O3上的加氢脱硫反应产物分布及其可能的反应网络,并通过反应压力和温度对产物分布的影响,揭示了加氢脱硫反应的可能机理.研究发现,4,6-DMDBT在Co-Mo/γ-Al2O3上存在甲基位置转移的异构化反应,而4,6-DMDBT加氢脱硫反应通过直接氢解路径和加氢路径进行,其中加氢路径起主要作用.通过4-甲基二苯并噻吩(4-MDBT),二苯并噻吩(DBT)的对比试验表明,二苯并噻吩类加氢脱硫转化率4,6-DMDBT<4-MDBT<DBT,而反应产物中联苯类与环己基苯类的摩尔分数之比,也存在上述顺序,加之实验发现的4,6-DMDBT部分加氢产物加氢脱硫的高活性,都间接证明二苯并噻吩类硫化物在催化剂表面存在通过硫原子的端连吸附,4,6-DMDBT位于4,6位的两个甲基在加氢脱硫过程存在对"端连吸附"的空间位阻,这是造成4,6-DMDBT转化率低的主要原因.实验研究表明反应压力对4,6-DMDBT加氢脱硫反应中加氢路径的影响很大,而对氢解路径影响不明显;反应温度对4,6-DMDBT加氢脱硫反应中加氢路径和氢解路径都有很大影响,但对氢解路径的影响相对较大.4,6-DMDBT分子中甲基的供电子作用有利于苯环的加氢反应,从而降低了加氢路径反应活化能,却不利于4,6-DMDBT在催化剂表面通过硫原子的端连吸附,因而使氢解路径的反应活化能升高.     

喹啉、吲哚对二苯并噻吩在NiMoS/γ-Al2O3上加氢脱硫反应的影响

 在固定床高压微反装置中考察了喹啉和吲哚对二苯并噻吩(DBT)在NiMoS/γ-Al₂O₃催化剂上加氢脱硫(HDS)反应活性及反应路径的影响.结果表明,喹啉和吲哚对DBT的加氢脱硫反应具有抑制作用. 少量的喹啉和吲哚即可强烈抑制DBT加氢脱硫反应的加氢路径; 而当含氮化合物加入量高时,才能较为显著地抑制DBT加氢脱硫反应的氢解路径. 在相同的条件下, 喹啉对加氢脱硫反应的抑制能力比吲哚强. 产物分析结果表明, 氮化物对DBT加氢脱硫反应的抑制作用与其分子结构和加氢脱氮反应中间产物的种类紧密相关.     

复合分子筛负载Ni-Mo制备深度加氢脱硫催化剂

用硝酸改性的氢型全硅MCM-41与HY的复合分子筛作为载体,负载Ni-Mo活性金属制备了深度加氢脱硫催化剂,在高压固定床反应器上考察了它们对DBT的加氢脱硫活性,用XRD、N2吸附、TPR对载体及催化剂进行了表征.结果表明,掺杂一定量HY的催化剂表现出了较高的加氢脱硫活性,当载体中HY的含量为25%时,催化剂活性最高.Ni/Mo最佳摩尔比为0.75,在280℃时,DBT的转化率接近100%.TPR结果表明,HY和Ni加入,使催化剂还原温度降低,加氢脱硫活性提高;催化剂低温耗氢温度与加氢脱硫活性有较好的对应关系,催化剂还原温度越低,加氢脱硫活性越高.     

含氮化合物对柴油超深度加氢脱硫催化剂运行稳定性的影响

采用中型固定床加氢装置考察了含氮化合物对柴油超深度加氢脱硫Ni-Mo-W型催化剂运行稳定性的影响。通过元素分析、N₂吸附-脱附、热重 质谱(TG-MS)联用、X射线光电子能谱(XPS)、高分辨透射电镜(TEM)等表征手段研究了催化剂失活的主要原因。实验结果表明：原料添加含氮化合物后，主要影响了催化剂的初活性，运转初期反应温度提高了7~10℃，但对催化剂的稳定性影响不大。根据催化剂失活原因的分析发现，原料添加含氮化合物前后，催化剂失活的主要原因均与其表面积炭的形成、孔体积的损失和边缘W比例的下降密切相关。     

A Study on the Process Conditions of Removing Basic Nitrogen Compounds from Gasoline

The methods of hydrochloric acid extraction, liquid-solid adsorption, and complexation were used to remove basic nitrogen compounds from gasoline, and the efficiencies of three removal methods were studied. The experimental results show that the optimum range of the concentration of hydrochloric acid is 0.05 ∼ 1.0 mol L^-1, and the optimum extraction time is 20 min for hydrochloric acid extraction method. The efficiency of removal of basic nitrogen compounds reaches its top when the ratio of liquid to solid is controlled at 5:1, and that the optimum range of concentration of complexing agent is 15 ∼ 20 wt% for complexation. Under the conditions mentioned above, all the removal yields of basic nitrogen of these three present methods can exceed 90%.     

Use of a commercial mixture of volatile compounds from the fungus Muscodor to inhibit Salmonella in ground turkey and beef

Additional interventions to reduce the risk of Salmonella in ground meat products are needed in the industry. Fungi in the genus Muscodor produce an array of volatile compounds with antimicrobial activity. A commercial mixture of these volatile compounds (all considered to be GRAS), in proportions similar to that produced by the fungus, was assessed for its inhibitory activity against Salmonella in vitro. The minimal inhibitory concentration of the volatiles mixture for growth of Salmonella enterica in Mueller-Hinton broth was 0.5% (v/v). Exposure to the vapor phase of the volatile compounds similarly inhibited visible growth of Salmonella on agar (up to 6 cm zone of inhibition). Addition of the volatiles mixture (0.25%–1.0% v/w) inhibited Salmonella by 1.5 and 2.8 log₁₀ CFU in ground turkey (85% or 93% lean, respectively) and 2.2 and 1.7 log₁₀ CFU in ground beef (73% or 93% lean, respectively) during a 5 day period at 8 °C. Addition of the volatiles also inhibited growth of normal microflora on ground turkey at 8 °C by approximately 5.3 log₁₀ CFU. These findings indicate this mixture of volatile compounds retards growth of spoilage organisms and Salmonella in ground meat.     

Production of volatile compounds in the fermentation of chardonnay musts inoculated with two strains of Saccharomyces cerevisiae with different nitrogen demands

This paper studies the behaviour of two strains of Saccharomyces cerevisiae with different nitrogen requirements in the production of esters and higher alcohols during alcoholic fermentation. To carry out the study a chardonnay must with a high content of nitrogen compounds was used. The results showed that the strain with the highest nitrogen demand produced a higher concentration of esters during fermentation and gave rise to a wine with a somewhat lesser content of higher alcohols. The formation of volatile compounds was probably related to the consumption of nitrogen by the strains as the nitrogen nutrients act as precursors in the synthesis of esters and alcohols and regulate their production.     

Colloidal silver complex as an alternative to sulphur dioxide in winemaking

The use of sulphur dioxide in the food industry has come increasingly into question because it can lead to pseudo-allergies. The aim of this work was to study the effectiveness of a colloidal silver complex (CSC) as an antiseptic instead of SO₂ in both white and red winemaking. We show that the CSC at doses of 1 g/kg of grape is an effective antiseptic, able to control acetic acid and lactic acid bacteria development, allowing the growth of Saccharomyces cerevisiae at rates similar to those observed with SO₂, up to sugars were exhausted. Silver concentration in finished white and red wines, 18.4 μg/L and 6.5 μg/L, respectively, was well below the legal limits. Wine composition was slightly affected, but CSC wines had a lower alcoholic degree and acetaldehyde content than SO₂ wines. CSC is a promising antiseptic for wine industry, although a major drawback, its lack of antioxidant activity, should be considered.     

Theoretical Investigation of the Relationship between Impact Sensitivity and the Charges of the Nitro Group in Nitro Compounds

ABSTRACT

By means of density functional theory (DFT), the general gradient approximation method (GGA), and the Beck LYP hybrid functional and DNP basis set, nitro group Mulliken charges (Q _{NO 2} ) are calculated and defined to assess and correlate with the impact sensitivities (H ₅₀ ) of nitro compounds: very negative Q _{NO 2} and high H ₅₀ . By calculating, analyzing, and comparing, we find that Q _{NO 2} can be regarded as a structural parameter to estimate impact sensitivity and has more availability in almost all nitro compounds in contrast to the length of the C?NO ₂, N?NO ₂ , or O?NO ₂ bond R _{R ? NO 2} , molecular electrostatic potential (V _mid ), and oxygen balance (OB). At the same time, it has good reliability and accuracy even though there are some exceptions. According to the data in this paper, the compound may be sensitive (H ₅₀  ≤ 0.4 m) when its nitro group has fewer negative charges than about 0.23.     

Comparison Study for the Distribution of Organo-Sulfur Containing Compounds of Two Kuwaiti Crude Oil Distillates

Abstract

This paper deals with the comparison, analysis, and characterization of two Kuwaiti crude oil samples received from different origins. (Burgan and Al-Wafra oil fields). Systematic analysis was conducted for API gravity, sulfur content, metal content, and viscosity. The representative samples of the two Kuwaiti crude oils were fractionated into naphtha (IBP–170^○C), kerosene (170–265^○C), medium gas oil (265–355^○C), and heavy gas oil (355–550^○C) using an 80 L capacity autodistillation unit “AUTODEST-800” according to ASTM D2892 and ASTM D5236. Particular attention was paid to study the distribution of various types of sulfur compounds in each of these wide cuts, which was qualitatively and quantitatively estimated by capillary gas chromatography equipped with a sulfur chemiluminescence detector, which is suitable for a wide range of sulfur systems. The fingerprinting obtained from the analysis of GC-SCD showed different families of organo-sulfur compounds in crudes, including mercaptans, sulfides, thiophenes, benzothiophenes, dibenzothiophene, benzonaphtothiophene, and their alkyl derivatives. From the analyses the behavior and distribution of the refractory and unrefractory sulfur compounds in the two Kuwaiti crude oils can now be easily followed.     

焦化蜡油中含氮化合物的加氢反应性能

 以NiW/CTS为催化剂，在固定床加氢微反装置上考察了反应温度（633~693K）、压力（5~8MPa）、停留时间（0.5~2h）和氢/油体积比（400~1200）对辽河焦化蜡油中碱性和非碱性含氮化合物的加氢脱除律的影响规律，并对反应数据进行了宏观动力学分析。结果表明，提高反应温度、压力和停留时间都有利于含氮化合物的脱除，其中碱性氮比非碱性氮更容易脱除，受反应条件的影响也更大；随着氢/油体积比的增加，含氮化合物的加氢脱除率呈现先增大后减小的趋势。动力学分析表明，原料中的碱性氮和非碱性氮的加氢脱除在实验条件下均符合拟一级反应动力学。非碱性氮的加氢反应速率较小，制约了总氮的脱除，而氮杂环的加氢是非碱性氮加氢脱除反应的控制步骤。     

煤直接液化重油胶质和沥青质中杂原子化合物的分子表征

采用傅里叶变换离子回旋共振质谱(FT-ICR MS)研究沸点大于360℃的煤直接液化重油中胶质、沥青质的组成,通过在分子水平上对杂原子化合物进行表征分析胶质、沥青质中杂原子类型、碳数分布和等效双键(DBE)。结果表明,煤直接液化重油中胶质及沥青质中杂原子化合物的分子组成十分复杂,采用正离子电喷雾结合高分辨傅里叶变换离子回旋共振质谱鉴定出了N₁、N₁O₁、N₂、N₂O₂、N₂S₁ 5类不同分子组成的碱性氮化物和S₁、S₂ 2种含硫化合物;采用负离子电喷雾鉴定出了N₁、N₁O₁、N₁O₂、N₂、N₂O₁、N₂O₂ 6类非碱性氮化物和O₁、O₂、O₃、O₄、O₅、O₆、O₁S₁、O₂S₁、O₃S₁、O₄S₁ 10类含氧化合物,其中碱性氮化物相对丰度较高的是N₁类化合物,含硫化合物相对丰度较高的是S₁类化合物,非碱性氮化物相对丰度最高的是N₁O₂类化合物,含氧化合物相对丰度最高的是O₂类化合物。根据各类化合物的DBE和碳数分布,获得了煤直接液化重油中胶质、沥青质分子组成的重要信息。碱性N₁类化合物主要母核结构是吡啶和喹啉为中心官能团的化合物,非碱性N₁类化合物主要母核结构是苯并咔唑,S₁类化合物主要以高缩合、长侧链的稠环含硫芳烃为主,O₂类化合物主要母核结构是菲二酚及蒽二酚。     

Synthesis of 3,6-bis(3-azido-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine

The synthesis of 3,6-bis(3-azido-1,2,4-triazol-1-yl)-1,2,4,5-tetrazine (3) (BATTz) is described. The physical and explosive sensitivity properties of this material were determined. The heat of formation was measured to be 1376 kJ/mol by combustion calorimetry. Additionally, X-ray crystallography confirmed the structure of this high-nitrogen primary explosive.