A Model of Catalytic Cracking: Catalyst Deactivation Induced by Feedstock and Process Variables

Changes in the quality of the feedstocks generated by involving various petroleum fractions in catalytic cracking significantly affect catalyst deactivation, which stems from coke formed on the catalyst surface. By conducting experimental studies on feedstocks and catalysts, as well as using industrial data, we studied how the content of saturates, aromatics and resins (SAR) in feedstock and the main process variables, including temperature, consumptions of the feedstock, catalyst and slops, influence the formation of catalytic coke. We also determined catalyst deactivation patterns using TG-DTA, N2 adsorption and TPD, which were further used as a basis for a kinetic model of catalytic cracking. This model helps predict the changes in reactions rates caused by coke formation and, also, evaluates quantitatively how group characteristics of the feedstock, the catalyst-to-oil ratio and slop flow influence the coke content on the catalyst and the degree of catalyst deactivation. We defined that a total loss of acidity changes from 8.6 to 30.4 wt% for spent catalysts, and this depends on SAR content in feedstock and process variables. The results show that despite enriching the feedstock by saturates, the highest coke yields (4.6–5.2 wt%) may be produced due to the high content of resins (2.1–3.5 wt%).

Kinematic Viscosity Prediction Guide: Reviewing and Evaluating Empirical Models for Diesel Fractions, and Biodiesel-Diesel Blends according to the Temperature and Feedstock

Experimental analysis of viscosity can be a straightforward and inexpensive analysis for few samples. However, in industrial processes that have high demands of properties measurements, the determination of viscosity and other properties involves time-consuming with sampling, analysis and availability of results. Also in refineries, the sampling routines for experimental determination of the viscosity of streams are not enough to represent variations that occur in the process, such as the shift of an oil tank in distillation units. In addition, besides requiring cost of operating personnel and laboratory analyst, all of these steps can take up to one shift until the result is available. Therefore, as an alternative, the use of predictive methods of kinematic viscosity are essential. Empirical methods have been used in simulations and design calculations of streams and mixture at industries regarding kinematic viscosity (KV) of petroleum fractions and fuels at different temperatures. However, there are uncertainties about the most accurate method to use at specific condition (temperature, feedstock, volume fraction) which might affect the KV prediction of fuels with unknown composition. Therefore, we assembled and evaluated several methods to predict KV of different diesel systems. In addition, new methods for predicting KV of diesel fractions at several temperatures were also developed for improving the estimation accuracy. As a result, we developed a guide with suggestions of the most accurate models to be applied for diesel fraction from assays, diesel fractions S500 from blend system at several temperatures, and biodiesel-diesel blends at different temperatures, volume fractions and feedstock.

OXIDATIVE DESULFURIZATION OF PETROLEUM PRODUCTS

The modern world market makes stringent requirements for the quality of motor fuels, in particular for sulfur content in them. The main classes of sulfur-containing compounds in petroleum fractions are thiols, dialkyl and cycloalkyl sulfides, alkylaryl sulfides, as well as heteroaromatic compounds – benzothiophene, dibenzothiophene and their alkyl derivatives. They have a negative impact on the quality of petroleum products. Growing demands on the quality of oil and petroleum products have led to the search for ways to reduce the sulfur content in oils and which would not lead to deterioration of physicochemical parameters of oil, such as viscosity, density, acidity, elemental and fractional composition, etc. Among the existing methods of desulfurization of oils and their fractions, special attention is drawn to oxidation methods that allow organic sulfur compounds to be converted into sulfoxides and sulfones which are easily removed by conventional separation methods, in particular by extraction or adsorption. The prospects of the oxidation method are due to the possibility of practical use of sulfoxides and sulfones in various sectors of the economy. The most common oxidants in the processes of oxidative desulfurization of petroleum fractions are hydrogen peroxide and alkylhydroperoxides in combination with catalysts that provide high selectivity and speed of the process. Transition metal compounds (Mo, V, W,) are most often used as catalysts because they are able to form peroxocomplexes in the presence of peroxides. Heterogeneous catalytic systems consisting of various solid carriers (salts, oxides, activated carbon, zeolites) and peroxide oxidants (hydrogen peroxide or alkyl hydroperoxides) are actively developing. Molybdenum-containing catalysts are one of the most efficient heterogeneous systems for oxidative desulfurization of diesel fuel. There is proved the effectiveness of oxidative desulfurization, which is a combination of catalytic oxidation of sulfur-containing compounds in the presence of a heterogeneous catalyst and adsorption on activated carbon. Methods of oxidative desulfurization with their advantages and disadvantages can be logical addition to large-tonnage hydrotreating processes, and also potentially can be used as an independent method of deep purification of oil and petroleum products from sulfur-containing compounds.

Photocatalytic Degradation of Synthetic Sulfur Pollutants in Petroleum Fractions under Different pH and Photocatalyst

Thiophene is one of the sulfur compounds in the petroleum fraction that can be harmful to living things and lead to a critical effect on the ecosystem. Photocatalytic degradation is one of the promising methods in treating wastewater as it can mineralization of pollutants into carbon dioxide and water. Other than that, this method is non-toxic and relatively low cost. The production of hydroxyl radicals playing a vital role in the degradation of organic pollutants. It has been claimed that the usage of zinc oxide (ZnO) nanoparticles could give an excellent degradation process as this photocatalyst have high photosensitivity, low cost and chemically stable. However, the preparation method of ZnO nanoparticles will affect the agglomeration, particle size, shape and morphology of particles and lead to influence the photocatalytic activity in degrading thiophene. Therefore, this study focused on the effectiveness of ZnO nanoparticles in the presence of fibrous nanosilica (KCC-1) and polyethylene glycol (PEG) as the capping agent to degrade synthetic thiophene. ZnO/KCC-1 had been synthesized via the precipitation method and characterized by using Fourier Transform Infrared (FTIR). The chemical bond and nature of the photocatalyst from the FTIR results proved that the synthesis process to produce the ZnO/KCC-1 was succeed. The large surface area of KCC-1 increases the effectiveness of ZnO which is supported by the experimental data. Accordingly, the optimum condition for photocatalytic degradation of thiophene is under pH 7 by using ZnO/KCC-1 as photocatalyst. Hence, it is believed that this research could be implemented to remove the thiophene in petroleum fraction from the actual industrial effluents and this can preserve nature in the future.

The alkylation of oil fractions rich in aromatic hydrocarbons with C6, C8 and C10 α - olefins in the presence of ionic liquids catalytic systems

The article is dedicated to the development of processes for (oligo)alkylation of petroleum fractions rich in aromatic hydrocarbons, with α-olefins (hexene-1, octene-1, decene-1) in the presence of ionic-liquid catalytic systems and the study of the properties of the products obtained. Alkylation reactions were carried out in the presence of chloroaluminate ionic liquids; for the first time a (nano)metal-polymer composite (NMPC) was used in the catalytic system as a modifier, and zinc chloride (ZnCl2) was used in the catalytic system as a component and the results were compared. It has been shown that these ionic liquid catalytic systems (ILCS) are suitable for (oligo)alkylation reactions and the use of these additives in their composition will lead to efficient alkylation. The products obtained were analyzed by IR-, NMR- spectroscopy, fluorescent indicator adsorption methods, and size exclusion chromatography. It was shown that these petroleum fractions rich in aromatic hydrocarbons can be used as alkylation components, and depending on the composition of the ILCS, it is possible to regulate the molecular, thermophysical and other characteristics of the products obtained based on them. The alkylated products obtained have been tested as plasticizing additives in polyolefin composites.

Characterization of Pure and Undefined Petroleum Fractions of Messla and Sarir Crude Oils of Libya Using Correlation Models

<p>Knowing the physical properties of hydrocarbons and petroleum fractions is essential for designing most crude oil production and refining processes. Several correlations, called group contribution methods, have been proposed in the literature to assess these parameters and have been used extensively. The majority frequent correlations reported in the literature, where it is generally accepted in the petroleum industry, are used to describe unspecified fractions of oil. The only input parameters required are specific gravity and normal boiling point or molecular weight. Calculated properties include: normal boiling point (T_b), Molecular weight (Mw), critical properties for instance critical pressure (P_c), critical temperature (T_c), critical volume (V_c) and acentric factor (ω), as well as other parameters including Watson factor (K), and compressibility factor (Z_c). In this approach, x samples of petroleum fractions of Messla and Sarir crude oils of Arabian Gulf Oil Company, Libya have been collected. A quantity of characterization technique of untainted and unknown petroleum fractions have been presented to foresee the physical properties of these petroleum fractions. Correlations for characterizing non-specific petroleum fractions suppose precise seriousness and boiling point as input parameters. These correlations are Twu Correlations, Cavett Correlations, Kesler-Lee Correlations and Riazi-Daubert Correlations. The physical properties of the compounds in terms of specific gravity and (T_b) were shown on the algorithm and the correlation models for the auxiliary acids were corrected in this study. The considerations addressed revealed that there is no significant difference between the correlation models and the results obtained and it appears to be very close to the similar published data of the cited authors.</p>