THE IMPACT OF ASPHALTENES REMOVAL ON THE KINETICS OF RESIDUUM HYDROTREATING

Iraqi reduced crude (above 350°C) prepared in a laboratory distillation unit containing 15 trays was solvent deasphaltened at specified conditions using n-heptane as the precipitant Both the original and deasphaltened reduced crude was hydrotreated on a commercial Ni-Mo- alumina catalyst in a laboratory trickle bed reactor. This investigation was undertaken to understand the role of asphaltenes removal in the kinetics of the desulphurization, demetallization and deasphaltening processes. Kinetic analysis showed that the hydrotreating reactions of the deasphaltened reduced crude followed a first order kinetics. Rate constants calculated for the above reactions are higher than those obtained in the HDS process for the original full residuum.     

渣油加氢处理过程中氮分布与脱除规律的研究

在渣油加氢处理中试装置上,考察了渣油中氮化物在不同催化剂上的脱除规律。结果表明,渣油加氢产物中总氮、碱性氮和非碱性氮含量随加氢深度增加而呈逐渐减少的趋势,加氢产物的碱性氮占总氮比率却逐渐增加,总氮、碱性氮和非碱性氮的脱除率分别为51.8%,33.9%,58.5%,表明在加氢脱除过程中,碱性氮较非碱性氮更难脱除。加氢产物组分中碱性氮占总氮的比例由大到小依次为:沥青质组分>胶质组分>芳香分组分。氮在原料渣油和加氢产物组分中的分布规律为:胶质组分>芳香分组分>沥青质组分。     

渣油加氢处理过程中金属分布与脱除规律的研究

在渣油加氧处理中试装置上，考察了金属在不同催化剂上的脱除规律。结果表明，阿曼原料渣油经加氢处理后，镍、钒、铁、钠、钙脱除率分别为84．9％，93．8%,4，96．8％，34．0％，70．0％，镍、钒、铁比钠、钙更容易脱除。镍、钒、铁在脱金属催化剂上的脱除率分别为61．2％，80．8％，93．5％，大部分金属在脱金属催化剂上就已经脱除。渣油中的金属杂质主要分布在胶质和沥青质组分中，金属在胶质组分中分布比例较高，但较易脱除。加氢处理对组成分布的影响使得镍和钒在胶质和沥青质组分中的分布比例发生变化，未能脱除的金属主要残留在沥青质组分中。     

RESIDUUM HYDROTREATING/APPLICATION OF LIQUID- SOLID CHROMATOGRAPHY FOR THE STUDY OF HYDROTREATED PRODUCTS.

Iraqi reduced crude (above 350^°C) was hydrotreated in a fixed-bed reactor with commercial Ni-Mo-alumina catalyst. Reaction temperature varied from 320 to 400^°C over liquid hourly space velocity ranging from 0.82 to 2.6 h^-1. Hydrogen pressure was kept constant throughout all the experiment at 6.1 MPa with hydrogen/ oil ratio about 30D NL/L. Asphaltenes were precipitated from the reduced crude and hydrotreated products with 15 parts of n-pentane (by volume) to 1 part of sample. Then, the deasphaltened products were fractionated by liquid- solid chromatography for saturates, aromatics and polar- aromatics separation. The kinetic study of aromatics and polar- aromatics hydrogenation indicates that these reactions are well correlated with a second-order kinetics. The rate constants of aromatics and polar-aromatics hydrogenation were calculated. Finally, the apparent activation energy (Ea), enthalpy of activation (▵H)^* and entropy (▵S)^* were calculated for hydrogenation of aromatics and polar-aromatics of reduced crude during hydrotreating.     

通过HTRI软件模拟研究解决渣油加氢装置火炬热放空问题

在部分渣油加氢装置设计中,在热低压分离器顶部设安全阀,其泄放温度高达360 ℃左右,而系统火炬管网的设计温度通常在260 ℃左右,因此需要在装置内将高温的泄放气体冷却到260 ℃以下后再出装置。通过HTRI传热软件模拟计算,对几种冷却方案从经济上和易实施的角度上进行对比分析,最终优选出在装置的放空分液罐内嵌水冷却器的冷却方案。在放空管线上加翅片管或循环水套管冷却的方案适用于系统火炬放空线。     

RESIDUUM HYDROTREATING/APPLICATION OF LIQUID- SOLID CHROMATOGRAPHY FOR THE STUDY OF HYDROTREATED PRODUCTS.

ABSTRACT

Iraqi reduced crude (above 350^°C) was hydrotreated in a fixed-bed reactor with commercial Ni-Mo-alumina catalyst. Reaction temperature varied from 320 to 400^°C over liquid hourly space velocity ranging from 0.82 to 2.6 h^?1. Hydrogen pressure was kept constant throughout all the experiment at 6.1 MPa with hydrogen/ oil ratio about 30D NL/L. Asphaltenes were precipitated from the reduced crude and hydrotreated products with 15 parts of n-pentane (by volume) to 1 part of sample. Then, the deasphaltened products were fractionated by liquid- solid chromatography for saturates, aromatics and polar- aromatics separation. The kinetic study of aromatics and polar- aromatics hydrogenation indicates that these reactions are well correlated with a second-order kinetics. The rate constants of aromatics and polar-aromatics hydrogenation were calculated. Finally, the apparent activation energy (Ea), enthalpy of activation (?H)^? and entropy (?S)^? were calculated for hydrogenation of aromatics and polar-aromatics of reduced crude during hydrotreating.     

不同沥青质在十氢萘体系中的加氢转化反应性能研究

以十氢萘为溶剂,在高压釜中考察了不同溶剂抽提所得不同来源沥青质的加氢转化反应性能.结果 表明,十氢萘可以改变沥青质体系的分散性能并起到供氢剂的作用,使沥青质具有较好的加氢转化性能,转化率均在60％以上,焦炭产率低于原油体系.不同溶剂分离所得沥青质的结构和组成不同,戊烷沥青质的转化率高于同一原料的庚烷沥青质.石蜡基沥青质...     

实验温度对沥青质热解的影响

本项研究主要是通过不同温度条件下的沥青质热解实验,研究热解温度对生物降解原油中生物标志物的恢复可能产生的影响。研究结果表明 340℃时,沥青质组分具有最大的产油率。另外,300℃之前,热解温度对沥青质热解产物中生物标志物的组成分布影响较小。因此,对于采用生物标志物恢复的方法来进行油/油对比时,300℃是沥青质热解实验较合适的温度。     

RESIDUUM HYDROTREATING APPLICATION OF IH AND QUANTITATIVE CARBON-13 NMR SPECTROSCOPY FOR THE STUDY OF HYDROTREATED PRODUCTS

ABSTRACT

Bai-Hassan reduced crude (350^°C + ) was hydrotreated in fixed bed reactor with commercial Ni-Mo-alumina catalyst. H and quantitative C NMR are used to derive statistical average structure parameters of feedstock and hydrotreated products. The main aromatic hydrocarbons (of type C_ar,H + C_ar,CH₃ + C_ar,n + C_ar,I) of hydrotreated products decreases by temperature, (at mild conditions) particularly at lower space velocity. The severe operating conditions increases the main aromatic hydrocarbons. An approximate inverse correlation is observed between the behaviour of saturated hydrocarbons and the aromatics of type C_ar,H + C_ar,CH₃ + C_ar,n + C_ar,I during hydrotreating process. Higher temperatures show an increase in the percentage of alkyl aromatics of type C_ar,alkFurthermore, the severe operating conditions promotes the formation of the alkyl aromatics with H_α(ArCH₃) while it decreases the alkyl aromatic having H₈ and H₈ The kinetic study of napthenes formation indicates that this reactin is well correlated with a first-order kinetics. The apparent activation energy lpar;E rpar;, enthalpy lpar;? H rpar;and entropy lpar;? s?lpar; of activation are 23.630 KJ mol 18.390 kJ mol ^-1 and -225.95 J mol^-1 k^-1 respectively.     

渣油加氢反应动力学及失活模型

采用固定床连续操作装置进行渣油加氢中试研究.中试采集的大量数据作为建模基础,运用非线性拟合方法,拟合了渣油加氢动力学参数,建立了包括催化剂失活校正和操作条件校正的渣油加氢动力学模型.结果表明,该模型可以比较准确地预测渣油加氢处理过程.该动力学模型不仅可以预测不同操作条件下各反应的杂质脱除率,而且可以计算在保证杂质脱除率不变的条件下,各工艺参数之间的相互影响规律.     

COMMENT ON THE STUDY OF ASPHALTENES BY X-RAY DIFFRACTION

In the x-ray diffraction of carbonaceous materials, there is no logical reason to assume an interrelation between the intensity of the (002) peak, reflecting intermolecular “stacking” order of aromatic planes, and the fractional aromaticity f_a measured by carbon nuclear magnetic resonance. Approaches to the calculation of a diffraction-based aromaticity f₀₀₂ by comparing the intensity of the (002) peak to that of the γ-band at 450 pm, reflecting intermolecular order of saturated chain hydrocarbons, are fundamentally flawed. The use of diffraction linewidth data for peaks near 210 pm (“(100)”) and near 120 pm (“(110)”) to infer an aromatic diameter has difficulties in systems containing hydroaromatic molecules (e.g., tetralin) because the naphthenic moiety contributes to diffraction peaks in the 210 and 120 pm regions.     

加氢处理催化剂失活模型的建立与研究

根据青岛炼油化工有限责任公司加氢处理装置实际生产数据,建立了加氢处理催化剂RN-32V的失活模型,并对模型进行了验证。结果表明,模型计算的理论产品硫含量与实际产品硫含量的误差在允许范围内,说明所建立的催化剂失活模型可以较准确地预测催化剂的失活速率及使用寿命,对于优化装置操作,确保装置长期稳定运转有一定的指导意义。     

EFFECT OF PRECIPITATION TEMPERATURE ON THE COMPOSITION OF N-HEPTANE ASPHALTENES

Petroleum asphaltenes were separated from Boscan and Kuwait crude oils by n-heptane at constant temperatures ranging from -2 to 80 ° C. A decreased yield with increase in temperature was observed. The precipitated material was characterized using infrared spectroscopic functional group analysis, HPLC-size exclusion chromatography, vapor pressure osmometry, and elemental analysis. The change in vanadium porphyrin content was estimated for Boscan using UV-Vis. With elevated temperature the asphaltenes are more aromatic (lower H/C) and have higher apparent molecular weight, whereas the pattern of changes in functional groups and heteroatoms (NSO) are more complex and apparently dependent on the crude oil. Porphyrins and low molecular weight types were seen to stay in solution at increased temperature, and a specific extraction of these takes place above 40 ° C. Asphaltene solubility is seen to approximate the Flory-Huggins theory as small molecules go into solution before large molecules. Several other mechanisms may, however, be involved in the phase separation. The molecular size distribution curves obtained by HPLC-SEC were found to explain the trends found in the molecular weights by VPO.     

INFLUENCE OF TEMPERATURE AND SOLVENT ON THE PRECIPITATION OF ASPHALTENES

Asphaltenes has been precipitated from a Kuwait flash residue using different n-alkanes (n-C5 to n-C8) at various temperatures ranging from 4^°C to reflux temperatures of the used precipitants. Structures in the asphaltene fractions has been revealed using U.V. fluorescence spectroscopy, elemental analysis and to some extent 1H-nmr. These analysis shows that asphaltenes precipitated in the same amount but at different temperature and with different solvents have merely the same composition. For all n-alkanes the curves of precipitated amount versus temperature show maxima at about 25^°C, implying a shift in the solubility of the asphaltenes.The impact of alkane chain length on the aggregation of asphaltenes through hydrogen bonds is discussed using the alkane-alcohol system as a model. The asphaltene solubility is discussed with the help of the Scatchard-Hildebrand equation.     

COMMENT ON THE STUDY OF ASPHALTENES BY X-RAY DIFFRACTION

Abstract

In the x-ray diffraction of carbonaceous materials, there is no logical reason to assume an interrelation between the intensity of the (002) peak, reflecting intermolecular “stacking” order of aromatic planes, and the fractional aromaticity f_a measured by carbon nuclear magnetic resonance. Approaches to the calculation of a diffraction-based aromaticity f₀₀₂ by comparing the intensity of the (002) peak to that of the γ-band at 450 pm, reflecting intermolecular order of saturated chain hydrocarbons, are fundamentally flawed. The use of diffraction linewidth data for peaks near 210 pm (“(100)”) and near 120 pm (“(110)”) to infer an aromatic diameter has difficulties in systems containing hydroaromatic molecules (e.g., tetralin) because the naphthenic moiety contributes to diffraction peaks in the 210 and 120 pm regions.     

镍在渣油加氢处理过程中的行为研究

采用4反应段固定床连续加氢处理装置研究了镍在渣油加氢处理过程中的变化,分析了混合渣油原料油及各步加氢处理油中镍的含量,并将各油样分离成八组分,对各组分中的元素镍进行了分析,讨论了原料油、各加氢处理油及分离组分中镍的分布变化及原因。结果表明,原料油中的镍主要集中在胶质和沥青质组分中,在保护剂段沥青质组分被大量脱除,并促使重组分中部分镍的存在形式发生一定的转化,减轻了后续床层催化剂的负荷,镍主要在加氢保护剂段和加氢脱金属段被脱除,有利于延长下游催化剂的使用寿命;经连续加氢处理后,镍含量明显降低,由25.4μg/g儋降低到5.3μg/g,镍的累积脱除率达到79.1%。     

EFFECT OF DISPERSANTS AND FLOCCULANTS ON THE COLLOIDAL STABILITY OF ASPHALTENES

Since the traditional deasphalting process is expensive, a more economical approach would be to use dispersants or flocculants to control the colloidal stability of asphaltenes. The asphaltene content of fuel oils is defined by testing the n-heptane insolubles following the ASTM D 3279 method. In the presence of dodecylbenzenesulfonic acid, a decrease in n-heptane insolubles precipitation was observed indicating an increase in their colloidal stability. No significant change in n-heptane insolubles precipitation was observed in the presence of dodecylphenol and nonylphenol. Poly(maleic anhydride-1-octadecene) polymer was found to be an effective flocculant. The flocculation of n-heptane insolubles varied depending on the polymer-to-asphaltenes weight ratios. The FTIR results indicate that the flocculation occurs through the H-bonding between the asphaltenes and the polymer molecules. Maleic anhydride was found to continuously increase the n-heptane insolubles precipitation with an increase in its treat rate. The FTIR analysis showed the presence of an acidic C=O group and no presence of an anhydride functional group. The results indicate that the presence of an anhydride and unsaturation makes the maleic anhydride too reactive leading to chemical changes and the precipitation of asphaltenes and other aromatic molecules found in fuel oils.     

THE CONCEPT OF ASPHALTENES REVISITED

Petroleum asphaltenes are defined as material insoluble in pentane or heptane and the nature of the molecular species that constitute asphaltenes has been a well researched subject over the past three decades. These investigations have led to a general consensus of the majority of researchers that asphaltenes contain condensed aromatic systems carrying alkyl, cycloalkyl, and heteroatom substituents. A variety of molecular models has been developed which have been used to explain the behavior of asphaltenes in feedstocks during recovery and processing operations

However, an alternate concept introduced the idea that asphaltenes can be defined as a complex mixture of organic compounds of varying molecular weight and polarity. This allows asphaltenes to be described more fully in terms of their behavior during processes and properties in products, such as asphalt

Thus, the concept can be used to explain, even predict, the incompatibility of asphaltenes with the other petroleum constituents as well as the deposition of asphaltic material on reservoir rock and the occurrence of sediments during refinery operations.     

EFFECT OF DISPERSANTS AND FLOCCULANTS ON THE COLLOIDAL STABILITY OF ASPHALTENES

Since the traditional deasphalting process is expensive, a more economical approach would be to use dispersants or flocculants to control the colloidal stability of asphaltenes. The asphaltene content of fuel oils is defined by testing the n-heptane insolubles following the ASTM D 3279 method. In the presence of dodecylbenzenesulfonic acid, a decrease in n-heptane insolubles precipitation was observed indicating an increase in their colloidal stability. No significant change in n-heptane insolubles precipitation was observed in the presence of dodecylphenol and nonylphenol. Poly(maleic anhydride-1-octadecene) polymer was found to be an effective flocculant. The flocculation of n-heptane insolubles varied depending on the polymer-to-asphaltenes weight ratios. The FTIR results indicate that the flocculation occurs through the H-bonding between the asphaltenes and the polymer molecules. Maleic anhydride was found to continuously increase the n-heptane insolubles precipitation with an increase in its treat rate. The FTIR analysis showed the presence of an acidic C=O group and no presence of an anhydride functional group. The results indicate that the presence of an anhydride and unsaturation makes the maleic anhydride too reactive leading to chemical changes and the precipitation of asphaltenes and other aromatic molecules found in fuel oils.     

渣油加氢催化剂预硫化方法的研究

采用抚顺石油化工研究院开发的FZC系列减压渣油加氢处理催化剂，在中试装置上进行两种不同方法的硫化试验，结果表明，在硫化压力、温度不变的情况下。适当提高硫化初期硫化剂用量，增大循环氢中H2S/H2比值。可以提高催化剂的硫化速度；在低温硫化段采用增加硫化剂用量的方法，可以有效地防止不利于催化剂预硫化的反应发生。进而提高整个催化剂系统的上硫率。硫化过程中较低的硫化氢浓度会对渣油加氢处理催化剂的脱氮活性和脱残炭活性产生较大影响。