Desulfurization Process Research Articles

Synthesis, Design and Evaluation of Innovative Combined Nano-Catalysts Supported on Activated Carbon Prepared from Apricot Shells

Abstract: Clean fuel oil is crucial for a healthy environment and modern life. Therefore, removing sulfur-containing compounds is an effective issue using various techniques for desulfurization. In this study, the oxidation desulfurization (ODS) process was utilized with respect to the prepared new activated carbon (AC) made from apricot shells (AS) loaded by two combined active metals (Nickel-Cobalt-Manganese (NCM) and Nickel-Cobalt-Manganese-Molybdenum (NCMM)). Several characteristics related to the catalysts prepared (mainly SBET, pore volume, FTIR, TGA, SEM, EDX and XRD) have been investigated to analyze the produced nanocatalysts. The new nanocatalysts (NCM/AC and NCMM/AC) were generated by using the impregnation wetness incipient (IWI) method and evaluated for their ability to remove sulfur compounds from whole-cut fuel (from 29-345 °C) based on the air as an oxidant within batch reactor under the following conditions: air flow rate = 2 lit/min, reaction temperature = 90 °C, and reaction time of 60 min for both catalysts. It was found that Nano catalyst NCMM/AC performed better overall in removing sulfur components (57.29 %) than Nano catalyst NCM/AC (44.75 %), and excellent properties have been observed.

SO3/sulfuric acid mist removal in simulated flue gas: Multi-factor study based on two-film theory mass transfer process

SO3/sulfuric acid mist is a strongly irritating pollutant presented in small quantities in flue gas, which poses a major threat to the power plants operation and atmospheric environment. In this study, SO3/sulfuric acid mist at different positions and after different spraying time of the small desulfurization tower were extracted and absorbed by isopropanol solution, and the SO42- concentration was detected by barium-thorium titration. Then the SO3/sulfuric acid mist mass transfer model in desulfurization process was constructed on the basis of two-film theory to investigate the effects of different tower structures, spraying time and operating conditions on SO3/sulfuric acid mist removal in desulfurization tower. The results showed that the tower structures had the greatest influence on SO3/sulfuric acid mist removal, and the highest SO3/sulfuric acid mist removal efficiency was achieved after the spraying time of 0–20 min and at the flue gas distribution plate. Moreover, according to the results of SO3/sulfuric acid mist mass transfer model, SO3 removing process was not controlled by solid dissolution instead of by gas–liquid film turning to gas film with flue gas residence time running in the tower. The model results also showed that SO3 removing process was controlled by gas film for a very short period then turning to gas–liquid film immediately with spraying time accumulating in a specific tower position. Besides, it showed the increase of NH3 concentration and spraying flow rate promoted the SO3/sulfuric acid mist removal, and the increase of SO2 concentration and slurry temperature inhibited the SO3/sulfuric acid mist removal.

Preparation of a novel BiVO4-Ni(Ⅱ)/g-C3N4 bifunctional photo electrocatalyst for oxidative and absorptive desulfurization of model fuel

This investigation aims to remove sulfur-based compounds (SBCs) by a combination of absorptive and oxidative desulfurization processes. Accordingly, a series of novel Bi-based bifunctional photo electrocatalysts is prepared by thermal method and used to remove dibenzothiophene (DBT) as a source of SBC from n-heptane as model fuel. The catalysts are used in photo electrocatalytic, photocatalytic, and electrocatalytic desulfurization systems and their effect on oxidative and absorptive processes is compared. The catalysts showed higher efficiency in absorptive desulfurization (ADS) by electrocatalytic desulfurization (EDS) and better results in oxidative desulfurization (ODS) by photocatalytic desulfurization (PDS). Among the results, photoelectrocatalytic desulfurization (POEDS) performed best in DBT removal (94%). The catalyst characterization was carried out with various analyses such as XPS, Raman, FTIR, DRS, TGA, FESEM, TEM, and chronoamperometry. The effect of adding radical scavengers on desulfurization was studied to determine the reaction mechanism. The stability of the selected catalyst is examined by repeating the reaction under optimum reaction conditions.

Reaction Behavior of Kaolinite in Sulfur-Bearing Sodium Aluminate Solution under the Simulated Bayer Process

Over a billion tons of high-sulfur bauxite has not been utilized effectively currently in China, because the pyrite existing in the bauxite poses a range of hazards during the Bayer process. A novel idea was proposed to remove sulfur by the silicon-containing minerals in bauxite reacting with sulfur species in sodium aluminate solution to form sulfur-bearing desilication products (SDSP) for discharge with the red mud in the Bayer process. This study investigated the reaction behavior between kaolinite and different sulfur-containing ions under the simulated Bayer process conditions, elucidating the desulfurization rate variation and formation mechanism of SDSPs. The thermodynamic calculations suggest that the reaction between kaolinite and sulfur-bearing sodium aluminate solution to form SDSPs can occur spontaneously. The experimental results demonstrated that various SDSPs can be produced through the reaction of kaolinite and sulfur-containing ions in sodium aluminate solution during the simulated Bayer process, resulting in various desulfurization efficiencies, while the desulfurization process will not result in additional alkali consumption. Increasing the kaolinite dosage, extending the reaction time, and elevating the reaction temperature all contribute positively to enhancing desulfurization efficiency. Kaolinite reacted with S2O32− in sodium aluminate solution to generate Na8Al6Si6O24S2O3·2H2O, achieving a desulfurization rate exceeding 90% under optimized conditions. Under the simulated Bayer digestion process conditions at elevated temperature, the desulfurization rates of kaolinite ranked in ascending order as S2− < SO32− < SO42− < S2O32−. Kaolinite reacted with SO42− and S2O32− to form cancrinite type SDSPs, and a superior desulfurization rate can be achieved. This work can provide a theoretical foundation and technological support for the efficient utilization of high-sulfur bauxite by the Bayer process.

Designing Al-SiO2 nanospheres with co-doped Ce/Cd for the removal of 4,6-dimethyldibenzothiophene of fuel oil

Catalytic oxidative coupled in-situ hydrodesulfurization technology as an emerging desulfurization process is applied to the removal of organic sulfides from fuels. In this study, Al-SiO2@Ce/Cd core-shell nanosphere catalysts were prepared by a sol-gel method and a co-impregnation method using silica as the carrier, and were in turn applied for the ultra-deep desulfurization of highly resilient 4,6-DMDBT from diesel oil under visible light irradiation. The prepared photocatalyst were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Brauner-Emmette-Teller (BET). Characterization results revealed that Al-SiO2@Ce/Cd had a nanosphere structure, and Ce/Cd were successfully loaded on the surface of Al-SiO2. Bimetallic loading helped increase the specific surface area of the SiO2 material, which could anchor more effective metal active sites. The effects of metal doping amount, doping ratio, catalyst dosage, and reaction temperature on 4,6-DMDBT desulfurization were studied. The results showed that 20% Al-SiO2@Ce/Cd achieved 100% desulfurization performance within 30 min at 60 ℃, thus surpassing many state of the art catalysts reported in literature. Al-SiO2@Ce/Cd remained highly active after 10 times successive reuses with rapid recovery by washing and filtering. Organic nitride had a strong inhibitory effect on diesel desulfurization, which was derived from the competitive adsorption of nitride and sulfide on the effective active site of the catalyst. Based on characterization results and desulfurization results, the appropriate reaction mechanism of the catalytic oxidative coupling in-situ hydrodesulfurization of Al-SiO2@Ce/Cd catalysts was speculated.

Theoretical investigation of the adsorption behavior of dibenzothiophene molecule on the surface of the pristine boron nitride nanosheet

The adsorption of the dibenzothiophene (DBT) molecule upon the boron nitride nanosheet (BNNS) was discussed using the DFT method by M062X/6-311 + G* level of theory in the water solvent. The results of thermochemical parameters display the interaction of the DBT with BNNS is a spontaneous and exothermic process. The UV/Vis absorption analysis was carried out to predict the changes that occurred during the adsorption of the DBT upon the BNNS. Based on the FMO analysis, the value of the energy gap (Eg) of the BNNS reduced after the interaction of the DBT with the BNNS. The negative value of ΔN (-0.0048) of the DBT@BNNS complex confirms the charge transfer from DBT to the BNNS which is inconsistent with the results of the NBO analysis. QTAIM analysis displays an electrostatic interaction between BNNS and DBT. According to the results of NICS calculations, after the interaction of DBT with BNNS, all three rings A, B, and C of DBT have become more aromatic and stable in the presence of the nanosheet magnetic field. We hope that our findings can be used for modeling and designing a suitable adsorbed for the adsorptive desulfurization process.

Polysulfide Concentration and Chain Length in the Biological Desulfurization Process: Effect of Biomass Concentration and the Sulfide Loading Rate.

Removal of hydrogen sulfide (H2S) can be achieved using the sustainable biological desulfurization process, where H2S is converted to elemental sulfur using sulfide-oxidizing bacteria (SOB). A dual-bioreactor process was recently developed where an anaerobic (sulfidic) bioreactor was used between the absorber column and micro-oxic bioreactor. In the absorber column and sulfidic bioreactor, polysulfides (Sx2-) are formed due to the chemical equilibrium between H2S and sulfur (S8). Sx2- is thought to be the intermediate for SOB to produce sulfur via H2S oxidation. In this study, we quantify Sx2-, determine their chain-length distribution under high H2S loading rates, and elucidate the relationship between biomass and the observed biological removal of sulfides under anaerobic conditions. A linear relationship was observed between Sx2- concentration and H2S loading rates at a constant biomass concentration. Increasing biomass concentrations resulted in a lower measured Sx2- concentration at similar H2S loading rates in the sulfidic bioreactor. Sx2- of chain length 6 (S62-) showed a substantial decrease at higher biomass concentrations. Identifying Sx2- concentrations and their chain lengths as a function of biomass concentration and the sulfide loading rate is key in understanding and controlling sulfide uptake by the SOB. This knowledge will contribute to a better understanding of how to reach and maintain a high selectivity for S8 formation in the dual-reactor biological desulfurization process.

Co-based metal-organic frameworks confined N-hydroxyphthalimide for enhancing aerobic desulfurization of diesel fuels

N-hydroxyphthalimide (NHPI) is a powerful green nitrogen-containing free radical catalyst, while the leaching of homogeneous NHPI remains a crucial obstacle. Herein, the cobalt-based metal–organic frameworks (Co-based MOFs) were introduced as the supports and co-catalysts to successfully confine the NHPI catalyst. NH3-TPD characterization confirmed that the heterogeneous catalyst NHPI@Co-MOF containing carboxyl groups linker exhibits more assertive acidity, facilitating the activation of O2 to generate active radicals O2•− that determined the catalytic activity. Owing to these features, NHPI@Co-MOF-DA with two carboxyl groups as the linker achieved 98 % of DBT conversion at 120 °C. Moreover, the DBT conversion of the used catalyst reached 95 % after being recycled 10 times. The distinctive design strategy provided valuable insights into the selection of suitable organic linkers to enhance the synergistic effect of metal cobalt with NHPI in the oxidative desulfurization (ODS) process, broadening the research horizon of MOF hybrids in the construction of efficient ODS applications.

Efficient immobilization of acids into activated carbon for high durability and continuous desulfurization of diesel fuel

AbstractFuel contaminants are the most critical issues in human health, cars' engines life and performance, and refinery equipment, and have an ultimate consecutive economic negative impact over time. Nowadays, sulfur is considered as one of the most dangerous contaminants in fuel, and different approaches have been carried out for desulfurization processing. In this study, new modified activated carbon (AC) for adsorptive diesel fuel desulfurization is carried out. To increase the robustness and effectiveness of a continuous adsorptive desulfurization (ADS) process, the study provides a new surface modification technique of the AC. Real diesel fuel (RDF, sulfur content 7510 ppm) and model diesel fuel (MDF, dibenzothiophene content 637 ppm) were used in a series of ADS tests carried out in a fixed‐bed adsorption column under atmospheric pressure and temperature. To achieve zero emissions of diesel fuel, the process parameters were optimized using the experimental findings. The AC and modified AC were tested via Brunauer–Emmett–Teller and Fourier Transform Infrared to evaluate the effect of the modification process on adsorbent characterization. The liquid hourly space velocity of the feedstock, the height of the absorber bed, and the kind of AC were the optimization parameters. In these circumstances, the ADS procedure was examined to address the impact of the feedstock flow rate on the effectiveness of ADS. The sulfur removal efficiency was 85.3% for RDF and 94% for MDF at 9 cm bed height, 8 h−1 LSHV, and 10 g bed weight, respectively. This is the first time that AC has been used to examine the stability of continuous ADS and to examine how acid immobilization affects sulfur removal. The investigation showed that the modified AC had a high rate of stability and was effective in the continuous ADS process. The spent modified AC was regenerated via a solvent extractive regeneration process to evaluate the durability of the ACs. The results proved that the regeneration performance of various solvents for modified activated carbon 1 decreases as follows: iso‐octane > ethanol > methanol > acetonitrile.

Ultrasounds assisted one-pot oxidative desulfurization of model fuel using green synthesized aluminum terephthalate [MIL-53(Al)

Oxidative desulfurization (ODS) is considered to be one of the most promising desulfurization processes as it is energy-efficient and requires mild operating conditions. In this study, a novel green synthesized Al- based metal–organic framework with high surface area has been synthesized hydrothermally using waste polyethylene terephthalate bottles (PET) as a source of terephthalic acid as an organic linker. The prepared Al based MOF have been characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The catalytic activity of the prepared Al-MOF was evaluated in the oxidative desulfurization (ODS) of both modeled and real crude oil samples. The different operating parameters (temperature, time, catalyst dose, oxidant loading and sonication) on the ODS performance have been optimized. The optimal conditions for maximum removal of thiophene from modeled oil samples were found to be 30 min, 0.5 g of catalyst and 1:3 oil to oxidant ratio. Under the optimized conditions, sulfur removal in real oil samples obtained from Alexandria petroleum company was 90%. The results revealed that, the presented approach is credited to cost-effectiveness, environmental benignity, and ease of preparation, predicting great prospects for desulfurization of fuel oils on a commercial level.

Advances in Resources Recovery of H2S: A Review of Desulfurization Processes and Catalysts

Advances in Resources Recovery of H₂S: A Review of Desulfurization Processes and Catalysts

Effect of Impeller Structure Parameters on Desulfurizer Mixing Behavior in KR Desulfurization Process

Effect of Impeller Structure Parameters on Desulfurizer Mixing Behavior in KR Desulfurization Process

A Computational Fluid Dynamics‐Thermodynamics Coupled Approach to Simulate Desulfurization in Ladle Furnace Based on Interface Equilibrium Assumption

This study proposes a coupled computational fluid dynamics and thermodynamics model based on the assumption of interface equilibrium at the steel–slag interface to simulate the desulfurization process in a ladle furnace. The species transport equation is solved to analyze the kinetic behavior and chemical content variation in the melt. The sulfur distribution ratio is calculated based on the slag sulfide capacity and oxygen activity. Subsequently, the solutions are coupled by introducing the species transfer and source terms generated by comparing the initial and predicted thermodynamic equilibrium states at the steel–slag interface cell. The model is validated by experimentally comparing the sulfur content. Furthermore, the model is applied under different kinetics and thermodynamics conditions. With an increase in the gas flow rate, the in‐phase effective diffusion coefficient increases, but the number of interface cells involved in the sulfur transfer process decreases. The complex relationship between the desulfurization process and the gas flow rate results from the mutual antagonism between these two factors. Moreover, the study findings demonstrate that a higher slag basicity enhances the calculated sulfur distribution ratio and final desulfurization ratio.

Design of Highly Efficient Nickel-Cobalt-Manganese-Molybdenum (NCMM) Nano-Catalysts Supported on Activated Carbon for Desulfurization Process

To maintain a healthy environment and way of life in the modern world, clean fuel must be produced. It is important to totally and successfully remove sulfur-containing harmful compounds from fuel oil in order to comply with the new sulfur legislation. Numerous methods have been proposed in the literature for desulfurizing fuel oil. In this study, activated carbon (AC), which is regarded as a significant porous material, is derived from agro-wastes such as apricot shells (AS) and is loaded with different combinations of active metals. Nickel–Cobalt–Manganese (NCM) over AC is firstly prepared and evaluated experimentally. Then, several concentrations of Molybdenum (1%, 2% and 3%) are separately added to NCM to generate three novel composite mesoporous nano-catalysts (NCMM_1, NCMM_2 and NCMM_3). Several tests have been carried out to determine the catalysts’ properties, such as BETsurface area, pore volume, FTIR, TGA and SEM, XRF and XRD. These catalysts are then used in the batch oxidative desulfurization process to remove sulfur compounds from wide cut oil (from IBP to 345 °C). The pilot plant conditions were as follows: air flow rate = 120 L/h, reaction temperature = 363 K and reaction time of 1 h for all catalysts. Remarkable characteristics have been noticed, and it was discovered that the nano-catalyst NCMM_2 performed better in terms of degree of sulfur removal compared to other nano-catalysts.

Influence of cationic surfactants on the growth of gypsum crystals

Abstract The effect of cationic surfactants on the growth of gypsum was evaluated under conditions of a simulated production process of gypsum desulfurization. We used a laser particle size analyzer and a microscope to determine the particle size and morphology. The growth rate of gypsum was determined by the equation for the rate of chemical reaction of CaSO4·2H2O. The results showed that the growth rate at a supersaturation ratio of 2.4 increased by 50% with 30 mg/L of a dodecyldimethylbenzylammonium chloride. The gypsum morphology changed from needle-like in the absence of additives to tabular in the presence of cationic surfactants, indicating that relatively thicker and larger crystals were formed. Finally, the investigated cationic surfactants were beneficial to the normal operation of the desulfurization process.

Desulfurization of Diesel Using Ionic Liquids: Process Design and Optimization Using COSMO-Based Models and Aspen Plus.

Sulfur dioxide emissions from fossil fuel combustion have been known to cause detrimental health and environmental effects. The currently used hydrodesulfurization (HDS) method employed by refineries has several drawbacks, such as excessive hydrogen consumption, high energy demand, and inability to remove complex organosulfur compounds, which have limited its ability to produce ultralow sulfur diesel (ULSD) at reasonable operating and capital costs. Ionic liquids (ILs) have been widely studied for their potential to replace conventional HDS. However, while their success has been demonstrated at the laboratory level, studies on industrial-scale feasibility and their integration into process simulators such as Aspen Plus are limited. In this work, 26 commercially available ILs have been screened using COSMO-based models and Aspen Plus for the desulfurization of diesel fuel and several possible process configurations have been examined. In particular, the challenge of ionic liquid regeneration, which has largely been ignored in the literature, has also been addressed and several potential regeneration methods have been proposed including extractive regeneration (E-RE) and stripping regeneration using nitrogen and air as stripping media (S-RE). The results indicate that, among the 26 ILs studied, 1-butyl-3-methylimidazolium thiocyanate is the most promising as a solvent for extractive desulfurization (EDS), E-RE, and S-RE. E-RE was found to be more effective for the removal of dibenzothiophene (DBT), while S-RE is more suited to the removal of thiophene and benzothiophene (BT). As a result, an optimized diesel desulfurization process using 1-butyl-3-methylimidazolium thiocyanate has been proposed that achieves ULSD with <10 ppm total sulfur in simulation studies, with complete recycling of the IL and minimal loss of the model diesel.

Insight into the relationship between effective active sites and ultra-deep adsorption desulfurization performance of CuCeY with different Cu precursors

Adsorption desulfurization processes employing zeolites as sorbents are considered to be prospective desulfurization methods owing to their cost-effectiveness.Y zeolites modified with Cu and Ce have excellent adsorption capacity and selectivity for adsorption desulfurization. However, the effect of using different metal precursors on the active sites of these sorbents and their adsorption desulfurization performance still remains ambiguous, which impedes the development of improved desulfurization adsorbents. Herein, Cu(NO3)2, Cu(Ac)2, and CuSO4 were selected as Cu precursors to prepare a series of CuCeY from CeY zeolite. Desulfurization experimental results indicate that outstanding breakthrough adsorption capacities for thiophene (ca. 6.25 mg·g−1) with benzene as the solvent were achieved by the CuCeYA. The interaction between the CuCe metals was beneficial for enhancing the electron transfer between Cu2++Ce3+/Ce4++Cu+. Moreover, using different copper precursors significantly changed the redox ability of the adsorbent surface. Changing the copper precursor also had a significant effect on the locations of Cu and Ce ions, and using Cu(Ac)2 as a metal precursor facilitated the migration of Cu+ (53.6%) and cerium species (35.9%) to the supercage. In situ infrared characterization showed that the oligomerization of thiophene on CuCeYA was significantly restricted due to the lowest B acid content (11.85%) in the CuCeYA.

Study on simultaneous removal of SO2 and NOx from sintering flue gas over Fe-Mn/AC catalyst

In this work, activated coke catalysts were modified with Fe or/and Mn oxides using an impregnation method. The catalysts were thoroughly characterized using various techniques, including XRD, SEM, XPS, TG-DSC and H2-TPR. The effects of Fe and Mn oxides modification on the catalytic performance of AC catalysts for simultaneous removal of SO2 and NOx were studied. The results showed that Fe-Mn/AC catalyst presented excellent catalytic activity for both SO2 and NOx. The co-doping of Fe and Mn oxides resulted in the formation of the microporous structures, which served as active reaction sites on the catalyst surface. The carbonyl group (CO) was found to play an active role in the oxidation of SO2 by forming a hydrogen bond, which reduced the energy barrier for the conversion of SO2 to SO3. Moreover, it was observed that the deposition of MnSO4/FeSO4 over Fe-Mn/AC catalyst was lower than that of Fe/AC and Mn/AC catalysts. Finally, a possible mechanism model for the denitrification and desulfurization processes over Fe-Mn/AC catalyst was proposed.

A comprehensive discussion on fuel combustion and desulfurization technologies

In the realm of environmental science, it is of the utmost importance to derive clean energy from fossil fuel stock. The primary goal of this review article is to inspect key barriers to the increase use of liquid fuels in the transportation sector. The combustion of transportation fuel releases a more significant number of air pollutants into the atmosphere, with sulfurous and carbonaceous species particularly damaging the environment and causing human health problems. Desulfurization, in this dynamic industry makes a significant contribution by removing sulfur compounds, ensuring the efficient utilization of fuels without the emission of harmful sulfur oxides (SOX emissions). Additionally, to minimize such pollutants, the Environmental Protection Agency (EPA) enacted strict regulations that mandate an ultra-low desulfurization process to comply with the sulfur standard. However, choosing a more appropriate and efficient catalyst has always been a challenge. Moreover, using our critical evaluation, inorganic hybrid molybdenum (Mo) based materials have significant role for both conventional and non-conventional technologies. The factors which can influence the activity of desulfurization catalysts such as temperature, solvent, and concentration are more clearly outlined. With this outline, herein, the current industrial techniques such as hydrodynamic cavity method and coupled desulfurization technologies have been proposed. Moreover, we highlight the technical challenges and scalability while adopting a particular method and address solutions based on contemporary advances. The present review article is expected to provide a clear and systematic understanding on the design and development of active catalysts for various desulfurization technologies. In the concluding section, the prospects and limitations for various Mo based catalysts are thoroughly summarized.

5-Aminotetrazoles – An Overview of Synthetic Methodologies through the Desulfurization of Thioureas

Abstract: Tetrazoles are important heterocycles in diverse branches of chemistry. Among the 5-substituted tetrazoles, the 5-amino derivatives are the most important by far as they show high chemical versatility and relevant applications in material chemistry, catalysis, agrochemistry, etc. Particularly in medicinal chemistry, they present a wide range of pharmacological properties. In the present review, we focus on the synthesis of 5- aminotetrazol from the desulfurization processes of thioureas using metal salts, hypervalent iodine compounds and halogenated reagents.