Katica Sertić-Bionda

Modeling of the FCC Gasoline Desulfurization Process by Liquid Extraction with Sulfolane

Abstract Extractive desulfurization of fluid catalytic cracking (FCC) gasoline with sulfolane was studied in a batch apparatus. The influence of three inlet parameters (temperature, inlet sulfur content, and solvent ratio) on the process response, that is, desulfurization efficiency, was investigated with the use of a Box-Behnken experimental design by response surface methodology. A mathematical model that can be used for predicting sulfur content in raffinate after extractive batch processing with sulfolane was statistically developed and proven with analysis of variance. Statistical analysis showed that the largest influence on desulfurization efficiency was solvent ratio, the second most significant influence was inlet sulfur content, followed by temperature, and last the interaction between solvent ratio and inlet sulfur content. The obtained second-order polynomial model shows that maximum desulfurization efficiency of 65.34% can be achieved at temperature of 50°C and higher values of inlet sulfur content and solver ratio in the researched range of inlet parameter values.

Desulfurization of Diesel Fuel in a Fixed Bed Adsorption Column : Experimental Study and Simulation

Abstract Desulfurization of diesel fuel was investigated in a fixed bed adsorption column using activated carbon as an adsorbent. The experiments were carried out at different feed flow rates, bed depths, and temperatures, and each experiment resulted in at least one sample containing less than 10 mg/kg of sulfur. Experimental data were used to simulate/predict the dimensions of an adsorption column for potential industrial application of adsorptive desulfurization of diesel fuel. The calculation resulted with a height of adsorption column of 17.32 m and an adsorbent load of 93.5 tons. The calculated column height is within the limits for a typical industrial adsorption column.

Oxidative Desulphurization of Diesel Fuels

Oxidative desulphurization (ODS) enables attainment of ultra-low sulphur content in diesel fuels by oxidation of refractory sulphur compounds that are difficult to remove with hydrodesulphurization when the sulphur content needs to be attained below 10 mg kg–1. In this work, the effect of the process conditions of ultrasound-assisted ODS (using N, N- dimethylformamide and methanol as extraction solvents) on real diesel fuels was researched. The experiments were conducted in a batch reactor with hydrogen peroxide as oxidant and acetic acid as catalyst. Temperature increase, reaction time extension, and increase in the amount of dibenzothiophene (DBT) in real diesel fuels showed a positive impact on the ODS process efficiency. Comparison of ultrasound-assisted ODS and ODS in a mechanically stirred system revealed a significant reduction in reaction time. The very low sulphur concentrations (3 mg kg–1) in the product obtained after 30 minutes of oxidation confirmed high efficiency of the oxidative desulphurization.

Impact of ultrasound application on oxidative desulphurization of diesel fuel and on treatment of resulting wastewater

The ultrasound-assisted oxidative desulphurization (UAOD) process of diesel fuel has gained growing attention due to the strict regulation of sulphur content in the fuel. The goal of the present study was to investigate the impact of ultrasound (US) application for oxidative desulphurization (ODS) of hydrocarbon fuels and for the subsequent treatment of produced wastewater, since sonochemical processes are a new and interesting area of research with wide application in the field of environmental engineering. For that purpose, the model diesel fuel with initial sulphur concentration of 1220–3976 mg l−1 was used for ODS and UAOD tests, and hydrogen peroxide/acetic acid was applied as the oxidant/catalyst system, respectively. The comparison of the process performance revealed that US significantly reduced the oxidation reaction time. The conversions of dibenzothiophene during 30 min of ODS and UAOD tests were 36% and 87%, respectively. Moreover, subsequent extraction with acetonitrile resulted in the final sulphur removal of 96.5%. The obtained results clearly indicated that UAOD process is beneficial for effective sulphur removal from the model diesel fuel. Furthermore, subsequent experiments included the application of the sono-Fenton process for resulting wastewater treatment. Monitoring of dibenzothiophene sulphone concentration and total organic carbon during the sono-Fenton treatment of wastewater revealed the decrease of 70–75% and 53–66%, respectively. The hypothesis on the possibility of degradation of dibenzothiophene sulphone by •OH radicals was confirmed by observed generation of benzoic acid and aliphatic carboxylic acids during experiments. Accordingly, the wastewater was purified to a satisfactory degree, enabling the reuse of treated water.

The correlation between HPLC parameters and topological indices of alkanes

SummaryThe possibility of predicting the parameters in HPLC by means of theoretical calculations, represents a significant step forward in the analysis of the complex mixtures of higher boiling petroleum fractions. Quantitative structure-property relationship, QSPR, is being used more and more in Chromatographic studies, since it is by now established that the retention indices have a structural origin. In the present paper we investigate whether the HPLC parameters of alkanes could be predicted from the QSPR-type models using the Wiener number as a structural descriptor. The Wiener number, which has already been applied in several cases to the prediction of gas Chromatographic retention indices and HPLC parameters for polycyclic aromatic hydrocarbons, has now been employed for calculating the HPLC retention time of n-alkanes and cycloalkanes.

Influence of weathering on oil spill identification

Abstract IR, UV and fluorescence spectroscopy are applied to identify oil spills on the sea. In order to establish the influence of weathering, the samples of crude oil, motor oil, heavy and light gas oil were weathered up to 15 days. Samples were taken every few hours, and analysed. The ratio of maximal absorbances were correlated with the time of the exposure. All ratios of maximal IR or UV absorbances decrease slowly with the weathering, so that identification of several oil samples was possible regardless of the time of weathering. Fluorescence spectroscopy cannot be applied if the samples contain only saturated hydrocarbons.

The influence of process parameters on catalytic cracking LPG fraction yield and composition

Abstract The influence of catalyst type, temperature, and feedstock, on the distribution of catalytic cracking products has been determined. The experiments have been performed according to the microactivity procedure MAT ASTM D-3907, with two commercial fluid catalitic cracking (FCC) catalysts and two gas oils as feedstock, at C/O ratio from 2.25 to 3.75, and in the range of 482–520°C. The effects of catalyst and feedstock properties on gasoline and liquefied petroleum gas (LPG) yields were established from the selectivity curves. Also, the influence of these parameters on the LPG composition and its applicability to alkylation and oxygenate production was determined in relation to the P/O ratios, as well as the corresponding isomerization/hydrogen transfer ratios. The temperature effects were in accordance with the thermodynamics of main catalytic cracking reactions.

Prediction of dibenzothiophene conversion in the ultrasound assisted oxidative desulfurization process

ABSTRACT In order to produce ultra-low sulfur diesel, ultrasound-assisted oxidation desulfurization of dibenzothiophene (DBT) was carried out with acetic acid and hydrogen peroxide. Due to its complexity, ultrasound-assisted oxidation process lacks a precise analytical solution. This paper explores the application of linear multiple regression and neural network for the prediction of dibenzothiophene conversion. Models were employed with respect to hydrogen peroxide dosage, temperature, reaction time, initial DBT concentration, and rate constant. The most accurate results were achieved by neural network model. Developed models facilitate future research in terms of better understanding the influence of process conditions of DBT conversion.

Study of nonisothermal gas-oil catalytic cracking applying the microactivity test

Catalytic cracking of gas oils has been studied in a standard microactivity test (MAT) reactor. The cracking product distribution was measured as a function of temperature. Based on these experimental results, a four-lump kinetic model was developed. Kinetic constants were estimated using the sequential step-optimization method. A nonisothermal nonsteady-state model for a fixed-bed MAT reactor was proposed. The overall heat of the reactions were taken from the macroscopic differences in the enthalpies of the products and reactants. The influence of the feedstocks used and reactor temperature were discussed. The reactor and kinetic model were validated with results from MAT test data. The simulation results are in good agreement with the experimental data.

Modeling of dibenzothiophene oxidative desulfurization using response surface methodology

ABSTRACT The effect of reaction temperature, mixing speed and oxidant to catalyst volume ratio, including their interactions on the oxidative desulfurization of dibenzothiophene by using response surface methodology was studied. Hydrogen peroxide was used as oxidant and acetic acid as catalyst. The obtained model accurately predicts conversion of dibenzothiophene and the best conversion of 98.7% was observed at temperature 70°C, mixing speed of 1250 rpm and oxidant to catalyst volume ratio of 1:1. At high temperatures, a major limitation of the desulfurization process is the mass transfer and the high mixing speed is needed to achieve an efficient process.