Heat-treatment of two heavy petroleum products containing vanadium and nickel

A raw coke very rich in vanadium (2–3%) and an asphaltene with a high content in nickel were studied by means of a high resolution transmission electron microscope, a scanning transmission electron microscope equipped with X-ray energy dispersive analyser and by X-ray diffraction. Vanadium diffuses out from the raw-coke during heat-treatment and forms small crystals of V₂O₃ trapped inside of carbon pores. After further heat-treatment vanadium carbide is formed which causes a catalytic transformation of the coke into a thermally stable partially graphitized carbon. In the asphaltene, nickel forms cubic crystals of metal at about 400°C. In both cases the metallic impurities are not uniformly distributed throughout the solid. All metallic matter becomes concentrated in a few particles, whereas most of the carbon is metal free. This appears to be common for samples of a low metallic content.     

Demetallization of heavy oil through pyrolysis: A reaction kinetics analysis

By tracking the transfer of vanadium and nickel in pyrolysis products, a seven-lump reaction kinetic model for pyrolysis-based demetallization of heavy oil was established. During pyrolysis, the demetallization of heavy oil is achieved by condensing metal-rich resins and asphaltenes to coke. The condensation of oil components originally contained in heavy oil differs greatly in reaction behavior, having the activation energy between 167 and 361 kJ/mol. As the pyrolysis progresses, the newly formed heavy components show a condensation behavior close to that of the light components. Limited by high activation energy and low initial fraction, the condensation of asphaltenes to coke and the resulting removal of metals contained in asphaltenes are hindered. Meanwhile, the condensation of light components has a major contribution to coke formation. An increase in reaction temperature accelerates the demetallization, but hardly changes the yield and component distribution of liquid products at the same metal removal rate.     

Continuous deasphalting of heavy petroleum residues with ethyl acetate

When crude oil is vacuum distilled, about 30% of the feed remain as low value residue. Hydrocracking can upgrade this residue into valuable light hydrocarbons. The hydrocracking could be optimized catalytically, if the residue were not to contain the metals vanadium and nickel that poison the catalyst. This contribution shows that continuous extraction of the residue with ethyl acetate yields a fraction with low metal content, while an asphaltene fraction with the remaining metal content is filtered off.     

Separation and characterization of clay from Athabasca asphaltene

Athabasca bitumen separated from the associated mineral matter by Soxhlet extraction contains fine clay particles and inherent ash. Empirical relations have been developed to estimate the percentage of clay and inherent ash present in the asphaltene fraction which concentrates in large measure the mineral constituents present in the bitumen. The ash level, Y, of the asphaltenes is related to the weight per cent of clay, C_t, by an expression of the form Y = 0.872C_t + 0.582. The ash level of the asphaltene fraction is also correlated with the infrared absorbance. A, at 1032 cm^?1 which gives an approximate empirical relation of the form A = 0.0648Y + 0.294. Greater accuracy at low ash levels can be achieved by measuring A at 1040 cm^?1 above the base line drawn from 960 to 1140 cm^?1. This results in the equation A = 0.0709Y + 0.0124 when a standard KBr pellet thickness of 0.833 mm and concentration of 2 mg asphaltene per 300 mg KBr is used. X-ray diffraction used to characterize the clay minerals shows decreasing crystallinity as the particle size diminishes. The infrared absorbance of this mineral matter indicates decreasing intensity of the band at 2930 cm^?1, associated with adsorbed and occluded organic matter, relative to the two characteristic clay bands at 3697 and 3620 cm^?1 as the particle size decreases. Trace element analysis of the asphaltene inherent ash, by inductively coupled argon plasma, shows the major metallic constituents to be vanadium, nickel and iron with minor amounts of calcium, potassium, aluminium and sodium.     

Leaching of vanadium and other metals from Athabasca Oil Sands coke and coke ash

Flexicoker coke derived from Athabasca Oil Sands bitumen contains a number of heavy metals, including vanadium, nickel, iron and titanium, which are susceptible to extraction by hydrometallurgical procedures. The leaching behaviour has been studied as a function of pH, temperature and the presence of salts and redox agents. Greater than 50% extraction of the vanadium, iron and nickel can be achieved by acid leaches, but only about 20% of the titanium can be extracted. Weakly acidic leaches extract about 30% of the nickel content but no significant amounts of the other metals. If cokes derived from Athabasca Oil Sands bitumen by the flexicoking process or the conventional delayed-coker coking process are combusted at temperatures below 500 °C, the vanadium and nickel values in the residual ash are readily susceptible to acid leaching.     

注蒸汽条件下供氢催化改质稠油及其沥青质热分解性质

利用CWYF-Ⅰ型高压反应釜模拟热采条件下,以甲酸作为供氢体.以自制的油溶性有机镍盐为催化剂进行的稠油水热裂解反应.考察了供氢体的加入对催化水热裂解反应前后稠油黏度、族组成及硫含量的影响,并采用TG-DTA分析法对供氢催化改质反应前后稠油中沥青质的热转化行为进行了分析.结果表明,随着加入供氢体质量分数增加,供氢催化水热裂解后稠油降黏率增大,饱和烃、芳香烃含量增加,胶质,沥青质含量降低,同时硫含量下降.供氢催化水热裂解反应后的稠油中沥青质TG-DTA曲线分析表明,供氢催化水热裂解反应后稠油中沥青质失重量高于催化水热裂解反应前稠油中含有的沥青质的失重量.经过供氢催化水热裂解反应,稠油中沥青质的稳定性下降.     

DFP新型钒镍钝化剂在RFCCU的工业应用

在研究重金属镍、钒对烃类裂化催化剂中毒机理的基础上，通过具有一剂多能和协同作用元素间的复配和优化，并考虑工业应用的可行性和成本，研制了无毒、高效和稳定性好的DFP抗钒、抗镍双功能水溶性钝化剂，在乌鲁木齐石化公司1.2 Mt/a的重油催化裂化装置(RFCCU)进行了工业应用试验。结果表明，当原料油中掺质量分数为39％～42％的减压渣油，平衡剂上钒质量分数高达7.5×10^－9～9×10^－9，镍质量分数为5×10^－9～6×10^－9条件下，使用DFP钝化剂与国产钝化剂MP相比，轻质油收率提高0.45%,焦炭产率下降16％～20%,氢气产率下降25％～30%，平衡剂活性指数提高4～5个单位，使用方便，有显著的经济效益和社会效益。     

Upgrading studies with Californian,Mexican and Middle Eastern heavy oils

Detailed chemical composition data were obtained for five atmospheric resids and products prepared in a continuous pilot plant by Unicracking/HDS, Unocal's fixed bed residual oil hydrotreating process. The results showed that the reactivities for removal of sulphur, nickel, vanadium and coke precursors cannot be predicted from simple physical or chemical properties. In particular, sulphur and metals removal reactivities are not proportional to feed sulphur or metals levels. There is a correlation of metals removal reactivities with the fraction of total feed metals found in the resin fractions. The oils studied were Heavy Arabian, Hondo (from California), Maya (from Mexico), Gach Saran (from Iran) and a blend of typical West Coast refinery feedstocks.     

影响煤焦油沥青质测定量的工艺参数

煤焦油通过溶剂分析可定量分离为三部分：甲苯不溶物、沥青质和油相。本文主要研究了煤焦油在此分离过程中芳烃溶剂类型、萃取方法、甲苯溶液浓缩量、烷烃溶剂类型和正庚烷溶剂与甲苯溶液浓缩量的添加比例对煤焦油沥青质沉淀量的影响。结果表明,甲苯溶液浓缩量、正庚烷与甲苯溶液浓缩量的添加比例对沥青质沉淀量的影响较大,萃取方法次之,将苯替换成甲苯影响最小。当选择甲苯溶解煤焦油,超声萃取3h,甲苯溶液浓缩量9mL,正庚烷与甲苯溶液浓缩液的添加比例为20∶1时,煤焦油沥青质的沉淀量为13.4%。本实验表明煤焦油的分离工艺会影响沥青质沉淀量,故在研究煤焦油沥青质性质和结构时需注明沥青质的沉淀分离条件。     

石油沥青质的微观结构分析和轻质化

通过总结和深化对石油沥青质微观结构及其轻质化工艺的认识,探索沥青质有效转化途径,为解决重质油加工过程中沥青质轻质化的难题提供思路。首先对沥青质微观结构的研究进展进行了总结,并通过分析沥青质基本单元片层结构和构成纳微缔合结构的相互作用力,推测构成沥青质纳微尺度结构的只有少数似晶缔合体,大部分为非晶缔合体。通过分析沥青质轻质化工艺发现热裂化和加氢转化工艺并未实现沥青质的轻质化,沥青质大多缩合生成了焦炭产物,虽然溶解作用使得沥青质在超临界水中有部分转化,但由于释放的活性氢数量有限,解决不了沥青质缩合问题,焦炭产率仍然很高。液相加氢转化利用活性氢自由基终止沥青质大分子自由基的链反应避免了生焦,实现了沥青质的有效轻质化。通过分析沥青质转化过程中胶体体系的稳定性,发现维持热裂化和加氢转化过程中重油胶体体系的稳定性较差,以沥青质为中心的胶束与分散介质之间的转化性能差异导致体系发生相分离而生成焦炭。液相加氢转化工艺中,由于新建立的胶体体系的分散介质保证了稳定的沥青质胶束的溶解能力,而为沥青质的有效转化提供了优良的反应环境。本文对沥青质的纳微缔合结构提出了新的观点,同时指出对非晶缔合体进行有效解构是沥青质液相加氢实现轻质化的关键。     

Study of accelerated deactivation of hydrotreating catalysts by vanadium impregnation method

The main causes of catalysts deactivation for hydrotreating are coking and metals deposition. In this present work, accelerated deactivation of hydrotreating catalysts was studied. In this respect, vanadium which is deposited with nickel during hydrotreating reaction was impregnated into the fresh hydrotreating catalyst. Different percentage of vanadium was impregnated and their hydrodemetalization (HDM) and hydrodesulfurization (HDS) activities were studied in bench-scale reactor of heavy crude oil. Accelerated deactivations for both HDM and HDS were observed on vanadium impregnated catalysts. The rate of HDS deactivation was faster than that of HDM reaction. The rapid deactivation of HDS may be due to the coverage of active sites by impregnated vanadium atom. The deactivation is slower when the V loading is low; but above 10 wt% loading a rapid deactivation is observed. A comparison of deactivation is made in between normal deactivation and the deactivation by vanadium impregnation. It was found that deactivation by vanadium impregnation is lower than that of normal deactivation. It suggests that at initial stage the formation of coke causes deactivation of the catalyst whereas at later stage when metals sulfides deposition is quite high, these sulfides take part in deactivation.     

Transfer-hydrocracking of vacuum residue

Hydrocracking of Arabian Heavy vacuum residue conducted in the presence of metal supported active carbon catalyst gave large amount of distillates (70%) with small hydrogen consumption. Especially, the Yalloum coal derived active carbon catalyst showed high cracking activity. The yield of asphaltene in the product oil was very low, whereas the coke yield was relatively high. In the metal-free active carbon system, the coke yield and the content of olefins, sulfur compounds and asphaltene in the product oil were higher than those of the metal-supported active carbon system. These results suggest that asphaltene in feed oil was adsorbed on the metal supported active carbon catalyst and was decomposed or dehydrogenated on it to form coke and hydrogen atoms. The hydrogen atoms formed migrated on the carbon surface to reach the metal site and transferred to free radicals, olefins or organo sulfur compounds.     

E.s.r. of Alberta tar sand bitumen and thermally hydrocracked products

A study of the vanadium and free radical species present in Athabasca bitumen and thermally upgraded products from a hydrocracking pilot plant was carried out. The samples were separated into asphaltene, chloroform resin, tetrahydrofuran resin and oil components, and the fractions studied by electron spin resonance. All samples except the oil fraction contained vanadyl (VO²⁺) ions and free radicals. It was found that even mild thermal treatment of bitumen produced considerable redistribution of vanadyl groups among the fractions, whereas at the severest hydrocracking conditions 94 wt% of all vanadyl groups were associated with the asphaltene fractions compared with only 58.5 wt% in the original bitumen. As the hydrocracking severity increased, the asphaltene vanadyl concentration initially increased above the value for unreacted bitumen and then decreased to a lower value. On the other hand, the resin vanadyl concentration decreased continuously and more rapidly than asphaltene vanadyl concentration. This indicates that vanadyl groups associated with the resin fractions are less stable than those associated with the asphaltenes and also suggests that transfer of vanadyl groups from the resin fractions to asphaltene predominates at low severity while removal of vanadyl groups predominates at high severity. The average spin Hamiltonian parameters showed that the chemical environment of vanadyl ions in the THF resins was significantly different from the vanadyl environment in the other two fractions.     

Upgrading of bitumen with formic acid in supercritical water

Upgrading of bitumen was examined with formic acid in supercritical water (SCW) from 673 to 753 K and at a water/oil ratio from 0 to 3. Decomposition of bitumen in SCW + HCOOH gave higher conversions of asphaltene and lower coke yields than those of pyrolysis or with only SCW. Decomposition of bitumen was also conducted in SCW + H₂, SCW + CO, toluene and tetralin, which revealed that decomposition of asphaltene was promoted and coke formation was suppressed when using SCW + HCOOH. In SCW + HCOOH, an increase in the water/oil ratio promoted both decomposition of asphaltene and suppression of coke formation. Formic acid in SCW seemed to enhance the conversion of bitumen to lower molecular weight compounds because formic acid seems to produce active species in SCW. The low temperature region (ca. 723 K) was suitable for upgrading bitumen with formic acid in SCW since coke formation was strongly promoted at high temperature (>753 K). A reaction model was proposed and the model predicted that hydrogenation of the asphaltene core was important for the suppression of coke formation.     

不同老化气氛对催化裂化捕钒剂性能的影响

通过改变老化处理气氛,研究其对催化裂化捕钒剂性能的影响。在水蒸汽和氮气气氛下,含有捕钒组分的催化剂与不含捕钒组分的催化剂催化活性接近,捕钒组分的捕钒效果不显著。在水蒸汽和空气气氛下,随着空气体积分数由0增加到50%,不含捕钒组分的催化剂微反活性由58%升高到69%,重油转化率由68. 82%升高到74. 02%;含有捕钒组分的催化剂微反活性由60%升高到73%,重油转化率由70. 04%升高到77. 10%,焦炭和干气选择性也优于不含捕钒组分样品,体现了捕钒组分的捕钒效果。通过控制老化气氛中SO2质量分数为0或0. 16%,考察SO2对捕钒组分的影响,结果表明,SO2对此捕钒组分的性能影响较小。     

Mechanism of high-pressure hydrogenolysis of Hokkaido coals (Japan) 3. Chemical structure changes in coal asphaltenes during hydrogenolysis

Asphaltenes produced by hydrogenolysis of coal were further hydrogenated in a batch autoclave at 400°C and 22 MPa hydrogen pressure. Red-mud was used as a catalyst and sulfur as promoter. The hydrogen content of the residual asphaltene increases and the fraction of aromatic carbon and the fraction of protons bound to aromatic carbons decrease as the reaction proceeds, indicating that hydrogenation of aromatic rings occurs. Aromatic ring systems of more than 2 rings are relatively easily hydrogenated to 2 rings. However, 2 ring systems are not easily hydrogenated. The heteroatoms-to-carbon ratios are similar for both the oil and the residual asphaltene, but less than that of the original asphaltene. The main differences in the chemical structure between the oil and the residual asphaltene are the hydrogen-to-carbon ratio, the fraction of aromatic carbon, the molecular weights and the average degrees of crosslinking. The residual asphaltene is composed of trimers and/or oligomers of unit structures of two or more condensed aromatic rings bound together by crosslinks. The size and composition of the condensed ring systems varies about the average properties measured in these experiments. Cleavage of the crosslinks by hydrogenation and heteroatom removal produces oil, composed for the most part of monomers of unit structures of two condensed aromatic rings. Coals of different rank show similar behavior although the magnitude of the changes depends on rank.     

石油焦粉及玻璃中钒的测定

玻璃企业在采用石油焦粉为燃料时,焦粉中所含钒对玻璃的生产会产生一定的影响,如何测定焦粉中钒的含量,从而控制焦粉中钒对玻璃生产的影响。利用钽试剂分光光度法可以测定焦粉中钒的含量,试验表明,此方法实验结果真实可靠,方法简单易行,易于在玻璃企业中推广。     

Reaction of Athabasca asphaltene with tetralin

Interaction of Athabasca asphaltene with a hydrogen-donating solvent such as tetralin at temperatures between 195 and 390 °C has been investigated. The reaction resulted in lowering the molecular weight of the treated asphaltene. At 390 °C, 50% of the original asphaltene was converted into pentane-solubles and the sulphur and oxygen contents were each depleted by about 40%. The results, which were interpreted in terms of thermal cleavage of sulphide bonds, are complementary to those obtained in the radical-ion electron-transfer reduction of the asphaltene with potassium in tetrahydrofuran. The negligible amount of coke formation at 390 °C proves the excellent stabilizing properties of tetralin in thermal reactions.     

Characterization of needle coke feedstocks by magnetic resonance spectroscopy

Decant oil is the traditional petroleum-derived feedstock for the production of needle coke. However, with the dwindling supply of high-quality decant oil and potential availability of coal-derived liquids, alternative feedstocks are receiving attention. One of these is ethylene pyrolysis tar. The new materials are less suitable needle coke precursors and may need to be upgraded by structural alterations. Therefore, the structure of these materials is examined at the molecular level. The average molecular parameters for the aromatic and asphaltene fractions of decant oil and pyrolysis tar are reported, along with a method for calculating these parameters which is slightly different from the previously available procedures. These parameters indicate that the average molecule in the aromatic and asphaltene fractions of decant oil and pyrolysis tar differ in certain structural units. This difference possibly may be responsible for their different behaviour on pyrolysis.