Very stringent environmental regulations have limited the level of sulfur in diesel, therefore deep desulfurization of fuels is required. For that purpose, the frequently used industrial process is ...hydrodesulfurization (HDS) which enables effective elimination of sulfur compounds such as mercaptanes, thiols, sulfides, disulfides from diesel oil, but removal of thiophene sulfur compounds (benzothiophene, dibenzothiophene, 4,6 dimethyldibenzothiophene) is insufficient. Ultrasound assisted oxidative desulfurization (UAOD) as one of several new technologies enables performance under mild conditions without use of explosive hydrogen. A higher reactivity of thiophene sulfur compounds during UAOD also provides conversion into highly polar sulfoxides and sulfones that are easily removed by adsorption or extraction. Nowadays, different catalyst/oxidants systems are being studied to improve oxidation reaction efficiency and enhance the mass transfer in the interfacial region. In this paper, the effect of reaction temperature (40–70°C) and oxidation time (5–150min) for UAOD of model diesel fuel with a catalyst/oxidants system (acetic acid/hydrogen peroxide) was investigated in a 70ml batch reactor. Furthermore, the effects of different initial concentrations of dibenzothiophene (DBT) and of ultrasound amplitude were additionally examined to achieve efficient sulfur removal. The obtained results indicated that temperature and US amplitude of 70°C and 80% respectively were efficient for conversion of DBT (sulfur concentration up to 3976.86ppm). The results indicate a rise in the yield of sulfones at higher temperatures and subsequent extraction with N,N-dimethylformamide conducted after the process of oxidation at different solvent/oil ratio revealed sulfur removal efficiency of 98.35%.
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.
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.
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.
The artificial neural network models were developed to determine sulphur content in the hydrotreatment product. Two models for two different types of feed were developed: light gas oil and vacuum gas ...oil. The developed ANN models use 6 input variables that are continuously measured in the process and are in accordance with the engineering knowledge and thermodynamics of hydrotreatment processes. Given models show good predictability of sulphur content in the hydrotreatment product and are, therefore, used in practice for continuous monitoring and optimization. This kind of application can be easily developed in any other hydrotreatment process with the available adequate historical data.
Adsorptive desulfurization enables the attainment of ultra‐low sulfur content in hydrocarbon fuels by removing the refractory sulfur compounds, which are difficult to remove in hydrodesulferization ...(HDS) processing when sulfur concentrations below 10 mg kg–1 must be attained. In this work, diesel fuel was desulfurized by adsorption using activated carbon as an adsorbent and the adsorption was carried out in a fixed‐bed column. The output sulfur content of less then 0.7 mg kg–1 was achieved for the lowest flow rate of 1.0 cm3min–1 and the highest bed depth of 28.4 cm at 50 °C. In all the experiments, at least one output sample contained less then 10.0 mg kg–1 of sulfur with a longest achieved breakthrough time of 11.8 h. A mathematical model of the fixed‐bed adsorber was applied to describe the kinetics and to estimate the breakthrough curves. The model equations included a differential material balance for a liquid phase and a mass transfer rate expression. The ability of the model to fit the experimental data was shown to be satisfactory.
Adsorptive desulfurization is a very promising alternative to the conventional hydrodesulfurization process. It enables the attainment of ultra‐low sulfur content in fuels by removing sulfur compounds, such as benzothiophene and dibenzothiophene. Diesel fuel is desulfurized by adsorption on activated carbon in a fixed‐bed column and the process parameters are modeled.
A five-lump kinetic model had been developed for modeling of gas oil catalytic cracking. The experiments were carried out in a standard fixed bed micro-activity test (MAT) reactor. Distribution of ...the cracking product components was determined as a function of temperature. The sequential step optimization method was used to estimate the kinetic constants. A MAT reactor nonisothermal and the unsteady-state model was proposed. The overall heat of the reactions was established from the macroscopic difference of the products' and the reactants' enthalpies. The influence of the feedstock and the reactor temperature was discussed. The reactor and the kinetic models were validated using the experimental MAT results. Simulation results were in good agreement with the experimental data.
Removal of sulfur from diesel fuel by adsorption on a commercial activated carbon and 13X type zeolite was studied in a batch adsorber. Kinetic characterization of the adsorption process was ...performed applying Lagergren's pseudo-first order, pseudo-second order and intraparticle diffusion models using data collected during experiments carried out to determine the sulfur adsorption dependency on time. The experiments investigating adsorption efficiency regarding initial sulfur concentration were also performed and the results were fitted to Langmuir and Freundlich isotherms, respectively. Activated carbon Norit SXRO PLUS was found to have much better adsorption characteristics. The process of sulfur adsorption on the fore mentioned activated carbon was further studied by statistically analyzing data collected during experiments which were carried out according to three-factor two-level factorial design. Statistical analysis involved the calculation of effects of individual parameters and their interactions on sulfur adsorption and the development of statistical models of the process.
Diesel fuel desulfurization by different commercial activated carbons was studied in a batch adsorber. Experiments, carried out to determine the sulfur adsorption dependency on time, were used to ...perform kinetic characterization and to screen the best performing activated carbon. The equilibrium characterization of the adsorption process was also performed. The statistical study of the process was undertaken by way of a two‐level one‐half fractional factorial experimental design with five process parameters. Individual parameters and their interaction effects on sulfur adsorption were determined and a statistical model of the process was developed. Chemviron Carbon SOLCARB<?up><?tvs=‐0.7h>TM<?down> C3 was found to be the most efficient adsorbent. The kinetic pseudo‐second order model and Freundlich isotherm are shown to exhibit the best fits of experimental data. The lowest achieved sulfur concentration in treated diesel fuel was 9.1 mg kg–1.
Diesel fuel desulfurization with different commercial activated carbons is studied in a batch adsorber. Kinetic and equilibrium characterization of the adsorption process is performed and the results are used to screen the best activated carbon. The statistical study of the process is achieved by applying design of experiments methodology. A statistical model of the process is developed.
