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Sulfur compounds are major contaminants in diesel fuels and cause significant negative impacts on the environment, human health, and petroleum product quality. Oxidative desulfurization (ODS) has gained attention due to relatively mild operating conditions. However, ODS requires significant improvements in terms of productivity, reaction time, and conversion. This study reports the development of a highly efficient, rapid ODS process, in an oscillatory baffled reactor (OBR), to allow continuous, safe dibenzothiophene (DBT) removal. DBT conversion was studied as a function of temperature, residence time, oscillation frequency, and oscillation amplitude. By optimizing the operating conditions, up to 94 % DBT could be removed without further extraction in 3 min, at 80 °C, 4 Hz, and 6 mm. This is a substantial increase over comparable processes at this temperature and furthermore has been conducted in a reactor that scales up predictably, hence it is probable that this performance can be realized at an industrial scale.

The oxidative desulfurization (ODS) of dibenzothiophene in diesel fuel cut using a homogeneous liquid catalytic system in a novel reactor is presented. Hydrogen peroxide was the oxidizing agent and acetic acid was the liquid catalyst. The oxidation process was conducted in a meso-oscillatory baffled reactor ("mesoOBR") under mild operating conditions: atmospheric pressure, and 60 to 80 °C. The reactor was operated over a range of residence times (1-3 min), and frequencies and amplitudes of oscillation, leading to oscillatory Reynolds numbers in the range 64-383, and net flow Reynolds numbers in the range 5 to 16. The results showed that dibenzothiophene (DBT) removal in the OBR was significantly higher than in conventional processes under the same conditions (pressure of 1 atm and temperature near room temperature). The maximum DBT conversion was 94%, which was achieved in 3 min at 4 Hz and 6 mm amplitude. A significant improvement in the removal efficiency of DBT was achieved in OBR within only 3 minutes compared to previous studies, which required at least a half-hour reaction time to achieve the same or less removal efficiency. A reaction kinetic model was developed using the optimum experimental results achieved in the OBR. The apparent reaction order was 1, with significantly low apparent activation energies (24.7-29.0 kJ mol

This work focuses on the preparation, simulation, and optimization of the hydrodesulfurization (HDS) of dibenzothiophene (DBT) using a nanocatalyst. A homemade nanocatalyst (3 percent Co, 10 percent Mo/γ-Al2O3 nanoparticles) was used in a trickle bed reactor (TBR). The HDS kinetic model was estimated based on experimental observations over ranges of operating conditions to evaluate kinetic parameters of the HDS process and apply the key parameters. Based on these parameters, the performance of the TBR catalyzed by the nanocatalyst was evaluated and scaled up to a commercial scale. Also, the selectivity of HDS reactions was also modeled to achieve the highest yield of the desired hydrogenation product based on the desirable route of HDS. A comprehensive modeling and simulation of the HDS process in a TBR was developed and the output results were compared with experimental results. The comparison showed that the simulated and experimental data of the HDS process match well with a standard error of up to 5%. The best reaction kinetic variables obtained from the HDS pilot-plant (specific reaction rate expression, rate law, and selectivity) TBR have been utilized to develop an industrial scale HDS of DBT. The hydrodynamic key factors (effect of radial and axial dispersion) were employed to obtain the ratio of the optimal working reactor residence time to reactor diameter.

The biochars obtained from the pyrolysis of biomass at different conditions have the potential to be used as biofuels. Thus, as a critical fuel property, the higher heating value (HHV) of biochars must be determined to decide on their application area. However, oxygen bomb calorimeters that are employed for HHV determination are expensive. Also, analysis is time-consuming, needs specialists, and can suffer from experimental errors. Although some model equations are available for solid fuels (biomass, coal, etc.) to calculate HHV, biochar has different properties, and a new model is required. This study aims to form an artificial neural network (ANN) model in order to estimate HHV of biochars by using simple proximate analysis data of 129 different biochars. The experimental and the predicted model results showed good agreement that the ANN model presented the highest regression coefficient of 0.9651 and the lowest mean absolute deviation of 0.5569 among all models previously reported in the literature.

Wastewater and other harmful compounds can be produced from different industrial activities and may contains toxic compounds like phenols. At high phenol concentrations, the carcinogenic effects are more likely and the environmental problems are of high concerns. In this study, the removal of a very high phenol concentration from refinery wastewaters by Catalytic Wet Air Oxidation was investigated and compared with the predicted results by neural network model. Alumina-supported platinum catalyst was prepared, characterized, and examined in a trickle bed reactor. A back propagation neural network model constructed in three layers was used to validate the experimental results. The first layer had five inputs that represent different operating conditions of feed acidity, weight hourly space velocity, pressure, time, and temperature; the second hidden layer had 18 neurons; and the third one was represented by one output, namely, phenol conversion percentage. The experimental results showed that the very high phenol concentration was successfully converted to a safe concentration and to acceptable concentrations of intermediates. The predicted phenol conversion of the neural network model shows the least error compared with the experimental test.

In the present work, a nanocatalyst, γ-Al2O3 nanoparticle-supported CoMo, was prepared experimentally and evaluated through a hydrodesulfurization (HDS) process for removing dibenzothiophene (DBT) from diesel fuel systematically in a trickle bed reactor (TBR). The results of the prepared catalyst characterization tests (scanning electron microscopy, X-ray diffraction (XRD), XRD phase quantification, and Brunner-Emmett-Teller) showed good distribution of active metals (CoMo), difference in surface morphology, and high dispersion of active metals. The catalyst exhibited good metal-support interactions without impacting the surface area significantly. A fully automated TBR reactor was used to evaluate the activity of the prepared catalyst in the HDS process at ranges of operating conditions: temperatures (250-350 °C), pressures (6-10 bar), liquid hourly space velocities (LHSV) (1-3 h-1), and the activity of the prepared catalyst were compared to a commercial catalyst based on Co-Mo/γ-alumina. The results showed an obvious enhancement in the HDS process using the homemade nanocatalyst compared to the commercial catalyst. It has also been found that an increase in temperature led to an increase in the conversion from 68.77 to 91.57%, a little positive effect on conversion when pressure was increased, and a significant decrease in conversion (from 91.57 to 75.58%) as LHSV was increased. A kinetic model was developed for the HDS process to estimate kinetic parameters and apply the parameters in reactor design. The developed model showed that the DBT concentration in diesel fuel can be reduced significantly, 3000-240 ppm, at the optimum experimental conditions.

Bubble columns are widely used for contacting gas–liquid and gas–liquid–solid mass transfer/chemical reactions. Gas distributor is the most important accessory because it decides the bubble size/rise velocity and gas distribution. In this study, the effect of distributor design on hydrodynamics and mass transfer coefficient are studied at different operating conditions of height to diameter ratio, solid loading, and superficial gas velocity The overall gas holdup, is studied experimentally using a rectangular slurry bubble column operating at ambient temperature and pressure, using liquid paraffin (C9–C11), three heights to diameter ratios (6, 7.5 and 10) and silica as a solid phase (0 %, 9 % and 25 %) with oxygen as gas phase. Two types of distributor were used, perforated plate and ring type. The results showed that the overall gas holdup increased by increasing gas velocity and decreased by increasing height to diameter ratio and solid loading. Also, it is found that the perforated plate distributor gave a higher gas hold up than ring distributor at gas velocity higher than 0.03 m/sec. The following correlations are obtained: Plate distributor at presence of silica particles: ε g = 1.343 U g 0.0612 − 0.00891 ε s − 0.374 − 0.702 L D 0.041 4.904 − 0.0251 $$\eqalign{{{\rm{\varepsilon}}_{\rm{g}}} =& {\left({1.343{\rm{U}}_{\rm{g}}^{0.0612} - 0.00891{\rm{\varepsilon}}_{\rm{s}}^{- 0.374} - 0.702{{\left({{{\rm{L}} \over {\rm{D}}}} \right)}^{0.041}}} \right)^{4.904}}\cr& - 0.0251}$$ Ring distributor at presence and absence of silica particles: ε g = 0.216 U g 0.297 − 0.354 ε s 1.4671 − 0.127 L D 0.147 1.1206 + 0.058 $$\eqalign{{{\rm{\varepsilon}}_{\rm{g}}} = &{\left({0.216{\rm{U}}_{\rm{g}}^{0.297} - 0.354{\rm{\varepsilon}}_{\rm{s}}^{1.4671} - 0.127{{\left({{{\rm{L}} \over {\rm{D}}}} \right)}^{0.147}}} \right)^{1.1206}} \cr&+ 0.058}$$ There is a good agreement between experimental and predicted values with a percent of error less than 2 %. It has been found that the mass transfer coefficient is higher for ring distributor than the perforated plate and growing higher for heterogeneous flow regime and higher solid loading.

In this investigation, time average local gas holdup and bubble dynamic data were achieved for three L/D ratios of slurry bubble column. The examined ratios were 3, 4 and 5 in 18″ diameter slurry bubble column. Air-water-glass bead system was used with superficial gas velocity up to 0.24 m/s. The gas holdup was measured using four tips optical fiber probe technique. The results showed that the gas holdup increases almost linearly with the superficial gas velocity in 0.08 m/s and levels off with a further increase of velocity. A comparison of the present data with those reported for other slurry bubble column having diameters greater than 18″ and L/D higher than 5 was made. The results indicated a little effect of diameter on the gas holdup. A local, section-averaged gas holdup increases with increasing superficial gas velocity, while the effect of solid loading are less significant than that of the superficial gas velocity. Chaos analysis was used to analyze the slurry system.

The oxidative desulfurization (ODS) of light gas oil (LGO) is investigated with an in-house-designed catalyst consisting of cobalt oxide loaded on alumina (γ-Al2O3), in the presence of air as an oxidizing agent, under moderate operating conditions (temperatures of 403–473 K, liquid hourly space velocity (LHSV) = 1–3 h–1, initial concentration = 500–1000 ppm). The Incipient Wetness Impregnation (IWI) method of cobalt oxide over γ-alumina (2% Co3O4/γ-Al2O3) is used for the preparation of the catalyst. The optimal design of experiments is studied to evaluate the effects of several process variables (namely, temperature, LHSV, and concentration of dibenzothiophene) and their optimal values were found to be 473 K, 1 h–1, and 1000 ppm, respectively. For the conversion of dibenzothiophene to sulfone and sulfoxide, the results indicates that the IWI method is suitable to prepare this type of the catalyst. Based on the experiments, mathematical models that represent a three-phase reactor for describing the behavio...

article Thepresentstudyexploredanoveloxidativedesulfurization(ODS)methodoflightgasoilfuel,whichcombinesa catalyticoxidationstepofthedibenzothiophene compounddirectlyinthe presence of molecularairasoxidantto obtain high quality fuel for light gas oil. In chemical industries and industrial research, catalysis plays a significant role. Heightened concerns for cleaner air togetherwith stricterenvironmentallegislations on sulfur contentinaddition to fulfilleconomic have created a driving force for the improvement of more efficient technologies and motivating an intensive research on new oxidative catalysts. As the lower quality fuel becomes more abundant, additional challenges arise such as more

Despite the hydrodynamics of trickle beds experiencing pilot size, on the contrary, the possibility of measuring hydrodynamic parameters locally and for large scale and finding an indicator to pinpoint the flow regime from trickling to pulsing remains obscure, to assess the feasibility of getting such information the reactor bed was randomly packed with equal-sized spherical beads of 3 mm diameter. Gas and liquid holdup measurements and flow regime identification were achieved at various flow conditions from trickling to the pulsing regime by an optical probe method using time series processing method. This method is shown to be simple and efficient provides quantitative information about the gas and liquid holdup variation in different flow regime. The various experimental results were compared to available literature models and correlations for confrontation and recommendations. The trickle-to-pulse flow transition boundary shifted towards higher gas and liquid superficial velocities, aligning with the findings on a variation of holdup along the axial direction confirmed to broaden the trickle flow domain. [Correction added after online publication June 26, 2015: To unify the adjective everywhere in this manuscript, optic fiber probe was changed to optical probe.]

In this work, the performance of oxidative desulfurization (ODS) of dibenzothiophene (DBT) in light gas oil (LGO) is evaluated with a homemade manganese oxide (MnO2/γ-Al2O3) catalyst. The catalyst is prepared by the incipient wetness impregnation (IWI) method with air under moderate operating conditions. The effect of different reaction parameters such as reaction temperature, liquid hour space velocity, and initial concentration of DBT is also investigated experimentally. For developing a detailed and validated trickle bed reactor (TBR) process model that can be employed for design and optimization of the ODS process, it is important to develop kinetic models for the relevant reactions with high accuracy. The best kinetic model for the ODS process taking into account hydrodynamic factors (mainly, catalyst effectiveness factor, catalyst wetting efficiency, and internal diffusion) and the physical properties affecting the oxidation process is developed utilizing data from pilot plant experiments. An optimi...

In this work, mathematical models of carbon dioxide (CO2) absorption by monoethanolamine amine (MEA) in a falling film contactor are developed. The proposed models aim to predict conversion of the gas–liquid reaction along the contactor, gas–liquid interface temperature profile (axial and radial), liquid film thickness along the contactor length, axial and radial concentration profiles of reactants in liquid film, and axial and radial profiles of velocity in the liquid film. A code written in MatLab was used to obtain these profiles based on multi grid method through programming of kinetic and thermodynamic equations and physical properties of the absorption system. The mathematical model is validated by an experimental measurement based on absorption of CO2 gas by MEA solution. Four parameters are studied as independent variables namely, mole fraction of carbon dioxide in gaseous mixture, molar concentration of absorbent (MEA, volumetric flow rate of MEA, and its temperature. It is found that the entrance effect of the falling film contactor is related to axial distance from the contactor entrance exponentially: E=B0exp(−B1y) An optimization technique based on minimization of the sum of the squared error between the experimental and predicted composition of absorption process is used to obtain B0 and B1. It is found that reaction between carbon dioxide and MEA is instantaneous, and the axial conversion of carbon dioxide in the gas phase varies exponentially with the contactor length.

Two-dimensional (2D) bubble columns have been used in the literature to study the detailed flow field for evaluation and validation of computational fluid dynamics (CFD) and for developing the needed closures and interfacial forces models for gas-water systems. Hence, this work focuses on investigating the bubble dynamics (i.e., local gas holdup, bubble velocity, bubble chord length, and frequency) in a 2D bubble column. Two advanced measurement techniques were implemented in this work, high-speed video camera imaging and a four-point optical probe. A new method for analysis of video camera imaging was employed. The results of both techniques were compared. The results show good overall agreement between the two methods for the horizontal profile of both bubble size and gas holdup. The findings revealed a strong positive correlation between bubble size and gas holdup. It was found that video image analysis could become an accurate, noninvasive alternative to fiber optical probes, at least in 2D systems, a...

The recent economic climate, impact of government regulation, and new market trends has impacted the catalyst designers to improve the performance of catalyst. To achieve this goal, a series of experiments were conducted to focus on the influence of Ga and Re addition on the catalytic activity of Pt–Re/Al2O3 naphtha reforming catalysts. To supported γ-Al2O3 the Ga-Re-Pt prepare by using incipient wetness impregnation method. Many characterization tests are used such as scanning electron microscopy, temperature programmed desorption, X-ray diffraction and BET surface area. The liquid product yield tested by PONA method. In this study the benzene content is used as main performance criteria throughout many experiments performed at different liquid hourly space velocity, hydrogen/ hydrocarbon ratios and different operating temperature. According to the catalyst characterization tests the coimpregnation method showed good result in term of performance and properties. The catalyst exhibited good liquid product distribution and significant minimization of benzene content.

This research aims at developing a discrete kinetic model of the hydrotreating process of a crude oil residue based on experiments. Thus, various experiments were conducted in a continuous flow trickle bed reactor over a temperature range of 653–693 K, liquid hourly space velocity of 0.3–1.0 h−1, and hydrogen pressure of 6.0–10.0 MPas at a constant hydrogen to oil ratio of 1000 L L−1. The reduced crude residue had been assumed to have five lumps: naphtha, kerosene, light gas oil, heavy gas oil and vacuum residue. An optimization technique based on the minimization of the sum of the squared error between the experimental and predicted compositions of the distillate fractions was used to calculate the optimal value of kinetic parameters. The predicted product composition showed good agreement with the experimental data for a wide range of operating conditions with a sum of square errors of less than 5 %.