Quantitative Determination of Trace Heavy Metals and Selected Rock-Forming Elements in Porous Carbon Materials by the X-ray Fluorescence Method.

A new X-ray fluorescence (XRF) method is proposed for sample preparation and impurity quantification for elements heavier than sodium in carbon materials. The analysis is suitable for various materials including amorphous ones, such as petroleum cokes, with an impurity content higher than 0.01%. We compared a new method with the regular additive method to measure impurities in electrode graphite and petroleum coke. The XRF-based method provides the same sensitivity and accuracy and much greater reproducibility of the analysis results for variations in the sample mass, its density, and coverage by exciting X-ray radiation. The method does not require changes in the instrument software and is easily implemented on commercial analytical equipment.

Production of Isotropic Coke from Shale Tar at Various Parameters of the Delayed Coking Process.

This paper presents the results of studies on the production of coke at excess pressures of 0.15, 0.25, and 0.35 MPa with delayed coking of shale tar obtained by pyrolysis of oil shale in the Baltic Basin. To assess the quality of the resulting coke, properties such as the absolute density, yield of volatile substances, ash content, and total porosity were analyzed. The microstructure of the resulting coke was analyzed by X-ray diffraction, for which the evaluation criteria were the interplanar spaces d 002 and d 100 and the sizes of the Lc and La crystallites. The scanning electron microscopy (SEM) technique was used to confirm the results of the analysis of the formed structure of shale coke obtained earlier. The calcined samples were classified as cokes with an isotropic structure. In addition, the fractional composition of the obtained gasoline and gas oil fractions of delayed coking of shale resin was analyzed.

Technology of Petroleum Needle Coke Production in Processing of Decantoil with the Use of Polystyrene as a Polymeric Mesogen Additive.

The results of experimental investigations on the coking of decanted heavy gasoil of catalytic cracking with polystyrene in a certain concentration range to obtain petroleum needle coke with the most developed string-base anisotropic structure and a microstructure point of at least 6.2 corresponding to the super-premium grade are presented. Certain regularities have been established to improve the structural quality index of the resulting needle coke from the optimal content of polystyrene in the base raw material, including the extreme dependence of the quality indices of needle coke on the polystyrene content (10 wt %). The decrease in the quality indices of the obtained carbon material is a consequence of uncontrolled changes toward an increase in the system viscosity performance (the viscosity increases 2.7 times). The experimentally obtained coefficient of thermal expansion (CTE) of needle coke-synthesized samples within the temperature range of 40-500 °C showed a reducing trend in CTE depending on the polymer additive proportion in the feedstock; for example, at 300 °C, the CTE decreases to 5.732 × 10-6 °C-1.

Use of Partition Coefficients in a Hexane-Acetonitrile System in the GC-MS Analysis of Polyaromatic Hydrocarbons in the Example of Delayed Coking Gas Oils.

The partition coefficients' application in the hexane-acetonitrile system as an additional identification feature of polyaromatic hydrocarbons in the review gas chromatography-mass spectrometry analysis of delayed coking gas oils has been considered. The UNIFAC model was used to calculate the partition coefficients of polycyclic aromatic hydrocarbons. It is shown that methyl derivatives of naphthalene, fluorene, anthracene, and pyrene can be identified with an accuracy up to several methyl groups by the position of the figurative point on the partition coefficient-retention index plane. The experimental values of partition coefficients for naphthalene, anthracene, and pyrene are 0.82, 0.78, and 0.77, respectively. The appearance of one methyl group increases the partition coefficient by 0.15-0.2 on average. A total of 53 polyaromatic hydrocarbons were identified in this way.

Technology of Producing Petroleum Coking Additives to Replace Coking Coal.

Coke chemical companies often have a deficit of coals of particularly valuable grades, the coking coals. This work studies the opportunity of producing petroleum coking additives using delayed coking during heavy petroleum residue processing. Experiments for the production of a carbon material were conducted using three kinds of heavy petroleum residues of the oil refinery plant Ltd Kinef: the vacuum residue from crude atmospheric and vacuum distillation units (VR1), the vacuum residue from the vacuum distillation hydrocracking unit (VR2), and the visbreaker residue from the visbreaking unit (VR3). For the produced carbon material, the quality indicators were determined, and X-ray diffraction, thermogravimetric, and differential thermal analyses were conducted. The petroleum coking additive produced instead of the typical petroleum coke under a milder temperature regime had the required quality indicators, particularly, the volatile-matter yield within the range from 15 to 25 wt %, to be used in metallurgical production for partial replacement of coking coals in the charge to produce metallurgical coke.

Thermogravimetric Determination of the Kinetics of Petroleum Needle Coke Formation by Decantoil Thermolysis.

This work presents the results of thermogravimetric analysis of decantoil. The microstructure of the extracted petroleum coke during the thermolysis of decantoil in an inert nitrogen atmosphere at 1000 °C was studied by scanning electron microscopy and interpreted as acicular. The model free kinetic approach based on Friedman's isoconversion method was used to calculate the kinetic characteristics of decantoil thermolysis-activation energy and pre-exponential factor. The individual hydrocarbon composition of decantoil was determined by gas chromatography mass spectrometry, which was used to determine the activation energy of evaporation of its fractions. The total energy spent on the chemical reactions of cracking and thermopolycondensation was determined when the degree of decantoil conversion was changed from 0.1 to 0.9.