Fatemeh Gorzin, Jafar Towfighi, Fereydoon X Fereydoon Yaripour, Seyed Mohammad Mousavi,
Volume 2, Issue 4 (3-2019)
Abstract
In this study, sonochemical synthesis was used to prepare nanostructured HZSM-5 catalysts. The three most effective ultrasound related variables including ultrasound power, irradiation time, and sonication temperature were investigated. The combined effect of these variables on relative crystallinity and mean crystal size of HZSM-5 nanocatalysts was studied using a central composite design. Higher crystallinity and lower crystal size were obtained by increasing ultrasound power, irradiation time, and sonication temperature while there was an optimum range for mentioned variables. The maximum relative crystallinity and minimum mean crystal size were obtained as 55.51% and 62.37 nm, respectively, under the optimal conditions of ultrasound power (231 W), irradiation time (21.18 min), and sonication temperature (42.68 °C). The results confirmed that sonochemical method considerably increased crysatllinity and reduced crystal size of HZSM-5 nanocatalysts at lower time. Hydrothermal method produced catalyst with full crystallinity and mean crystal size of 893 nm with 120 min aging and 48 h crystallization in autoclave while sonicated HZSM-5 catalyst with 21 min sonication and 4 h crystallization has 55.51% crystllinity and 62.37 nm mean crystal size. On the other hand, no HZSM-5 phase was formed in hydrothermal method with 120 min aging and 4 h crystallization in autoclave. These results strongly suggests that a catalyst with smaller crystal size, higher crystallinity and BET surface area at lower crystallization time can be obtained by using ultrasound instead of aging step in HZSM-5 synthesis
Mojtaba Saei Moghaddam, Pedram Nasehi, Reza Asadi,
Volume 2, Issue 4 (3-2019)
Abstract
Dehydrogenation of alkane to alkene is a key process in petrochemical industry. Propylene has intermediate role to production many industrial polymers. In this research applying oxidative dehydrogenation method for propylene production and CO2 used as oxidant. By use of XRD, Raman, TEM, BET and EDX techniques the results have been analyzed. In XRD and Raman tests anatase phase and Titania nanotubes have been distinguished. TEM confirmed TiNTs with pure structure. Vanadium catalyst with 5% of vanadia synthesized by impregnation method. Adding silicon in support increased thermal stability of catalyst. Raman and XRD method confirmed good distribution of active phase on supports. VSiTi catalyst have 28.31% conversion and 51% selectivity in 550 oC. Improvement in yield of propylene production would be in result of higher surface area and good distribution of vanadia over modified Titania nanotubes.
Morteza Golmohammadi, Hadi Nasiri,
Volume 3, Issue 4 (3-2020)
Abstract
Research subject: Due to the public's attention on the environmental issues as well as strict environmental regulations, the eco-friendly methods for nanoparticles have received considerable attention in the recent years.
Research approach: In the present study, a mixed oxide nanoparticles containing cerium and zirconium (Cex-Zr1-xO2) was fabricated the in supercritical water (SCW) medium. The synthesized nanoparticles were characterized by various analyses, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
Main results: The results of the analyses demonstrated that fine nanoparticles with mean size of 13±3 nm, with high crystallinity, and with appropriate size distribution and surface area were synthesized by SCW. Moreover, an oxygen storage capacity (OSC) as high as 1.25 mmol O2/g was estimated for Cex-Zr1-xO2 nanoparticles through temperature programmed reduction in hydrogen (H2-TPR). According to the obtained results, the Cex-Zr1-xO2 nanoparticles could be a suitable candidate for catalysts of oxidation processes as well as three-way catalyst for control of automotive exhaust gases.
Mohsen Moradi, Afsanehsadat Larimi, Farhad Khorasheh, Reza Nematollahi,
Volume 4, Issue 3 (12-2020)
Abstract
Research Subject: The conversion of anthropogenous CO2 gas into value-add chemicals known as solar fuel technology attracted much consideration from the beginning of the 21st century owing to the potential of this technology in solving the climate change and energy shortage issues.
Research Approach: In the current study, Bismuth and copper modified TiO2 were prepared using sol-gel and wet impregnation method in order to investigate as a catalyst for photocatalytic conversion of carbon dioxide into renewable methane.
Main Results: The results of X-ray diffraction analysis, Field emission scanning microscope images and Transmission electron microscope images demonstrated that titanium dioxide nanoparticles with 20 nm in size were synthesized that after the addition of bismuth, the size of particles became smaller. Also, using energy dispersive x-ray analysis and elemental mapping technique, it was determined that the bismuth and copper were uniformly inserted in the prepared nanoparticles. Diffuse reflectance spectroscopy showed that the bandgap became smaller in bismuth and copper-containing samples, which resulted in visible light absorption. In addition, photoluminescence spectroscopy showed an impressive decrease in the rate of electron-hole separation in the prepared nanocomposite. The result of CO2 photoreduction experiments revealed that the incorporation of 3 wt% Bismuth and 1.5 wt% copper into the structure of TiO2 would increase the amount of methane production to 7.6 times greater than bare TiO2. This superior activity for methane generation could be related to the ability of bismuth compounds in adsorption and activation of carbon dioxide molecules and also the efficient separation of charge carriers given by copper. Additionally, the smaller particle size and increase in the surface area had also a positive effect on the CO2 reduction enhancement.
Hamid Karami, Mohammad Kazemeini, Saeed Soltanali, Mehdi Rashidzadeh,
Volume 5, Issue 3 (12-2021)
Abstract
Research subject: Hydrodesulfurization is one of the effective methods to remove sulfur compounds from oil fractions and improve fuel quality. One of the major challenges in this process is to find the proper catalyst support that performs best. In the meantime, modified supports with zeolite have allocated a lot of attention due to their strong acidic sites, specific surface area and high hydrothermal and chemical stability; But the acidity and volume of zeolite mesopores need to be corrected.
Research approach: In this study, first, hierarchical Y zeolite was prepared using post-synthesis (Dealumination) and using ammonium form of zeolite and NH4F solution (0.75 M) at 90˚C for 3h under reflux conditions. Physicochemical properties of zeolite were investigated by BET, FESEM, FTIR, AAS and XRD analyzes. Modified zeolites were used in the support synthesis of the HDS process catalyst. The sulfidation and performance evaluation of the prepared catalysts were carried out in the fixed-bed microreactor were performed with diesel cutting feed from the Isomax unit of the target refinery.
Main results: The results show that the volume of mesopores, specific surface area and SiO2/Al2O3 ratio in hierarchical zeolites has increased 0.073 cm3 g-1, 783.36 m2 g-1 and 5.2, respectively (initial values are 0.032 cm3 g-1, 567.18 m2 g-1 and 4.5). The results of zeolite analysis show the preservation of the structure and crystallinity during the zeolite modification process. The effect of zeolite modification, especially the Si/Al ratio variations, mesopores and specific surface area, was investigated on the activity of NiMo/Zeolite+Al2O3 catalysts. Increasing the acidity and improving the physicochemical properties of the modified zeolites has increased the catalyst performance in the process of diesel hydrodesulfurization (Conversion= 90%). Improving the activity of catalysts can be attributed to the positive effect of zeolites on the dispersion of the metallic site, surface area, acidity, optimal size of pores and volume of catalyst mesopores.
Hamid Karami, Saeed Soltanali, Shokoufe Tayyebi,
Volume 5, Issue 4 (4-2021)
Abstract
Research subject: In recent decades, hybrid optimizations methods based on natural phenomenon have placed special position according to their capabilities in finding optimal solutions without expensive computational loads and disassociation on choosing initial points
. Artificial Neural Network is used as one of the powerful tools of Artificial Intelligence for process simulation. The employment of the neural network in the modeling of m-Cresol alkylation process of with isopropanol as well as meta-heuristic methods in obtaining the optimal conditions for the catalyst and the reaction can prepare an effective step towards a high efficiency process.
Research approach: In the present study, the artificial neural network is applied to model alkylation of m‐Cresol with isopropanol process. In addition, the bee colony is employed in order to optimize the process yield. To verify its performance, the proposed method is used in prediction of the m‐Cresol conversion and Thymol selectivity of the alkylation process with isopropanol 120 data. In this process, the input variables are Weight Hourly Space Velocity (WHSV), pressure and temperature; m-cresol conversion and thymol selectivity are considered as the output variables of the neural network.
Five hidden neurons are considered for the proposed neural network. 120 data is used to train the neural network. The meta-heuristic approach based on bee colony (BC) is applied to maximize the yield of the process.
Main results: The results confirm that the proposed method develops the accurate model with an R
2 value of greater than 97.5%. The maximum yield is obtained 28.9% by bee colony algorithm with adjustable variables that are WHSV of 0.062 hr
-1, the pressure of 1.5 bar and the temperature of 300
oC. In addition, in order to achieve the better performance of the optimization algorithm, the appropriate values of acceleration coefficient and population size are chosen 100 and 10 during the trial-and-error phase.
Tahereh Ebrahimi Yazdanabdad, Ali Forghaniha, Mozhgan Emtyazjoo, Majid Ramezani,
Volume 6, Issue 1 (6-2022)
Abstract
Research Subject: In this study, Thiourea-functionalized super-paramagnetic nanoparticles were used as a heterogeneous catalyst in the Petasis-Borono Mannich reaction.
Research approach: In the first stage of this study, Fe3O4@SiO2 nanoparticles were synthesized as spherical core-shell nanoparticles such that Fe3O4 particles were considered as the core. Then in the next step, the characteristics of surface functional groups, crystal structure, magnetic properties, size and surface appearance of nanoparticles and the process of functionalizing the structure in layers, using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) were examined, identified and analyzed. Then, to evaluate the efficiency of the structure, it was used as a catalyst in the Borono-Mannich reaction of potassium potash. Infrared spectroscopy (FT-IR) and hydrogen nuclear magnetic resonance spectroscopy (HNMR) were used to investigate the structure of the products.
Main results: The IR spectroscopy results showed that the peaks appearing in 568 cm-1 and 670 cm-1 were related to iron-oxygen bond, the peaks in 1092 and 800-950 cm-1 were related to silicon-oxygen bond, which indicates the formation of silicon layer on nanomagnetic particles and the validity of the reaction products. The results also showed that the amount of saturated magnetite in about 23 emu/g increased with increasing complex ligand. X-ray diffraction analysis showed that the index peaks of (2θ= 21.25˚, 37.29˚, 43.73˚, 52.56˚, 65.09˚, 69.73˚, 76.81˚) were realized and for certainty of the formation of the desired magnetic nanoparticles in crystalline phase were used. The results of SEM analysis showed the structure of nanoparticles in a spherical shape and EDX analysis confirmed the presence of elements in the structure which included sulfur. Also, the thermogravimetric analysis index showed approximately 7% decomposition coefficient. The first, second and third decomposition were observed 1% by weight (60°C), 5% by weight (200 to 300°C) and 1% by weight (350 to 700° C), respectively. The highest yield of 68% was measured with 40 mg catalyst in acetonitrile. The structure of thiourea was properly stabilized in a magnetic nanocatalyst.
Shahin Heydari Orojlou, Saadat Rastegarzadeh, Behrooz Zargar,
Volume 6, Issue 2 (9-2022)
Abstract
Research subject: In the present study, titanium dioxide/silver nanocomposites (TiO2/Ag) were synthesized by sol-gel method and their performance for photocatalytic removal of metribuzin was compared with commercial TiO2 catalysts P25 Degussa.
Research approach: The synthesized nanocomposites were evaluated using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDX). The effect of operating parameters including reaction time (0-240 minutes), pH (9-4), catalyst dose (0.005-0.015 g), temperature (10-60 ºC), visible light and UV light radiation, concentration Initial metribuzin (10-25 mg/L), the catalyst effect in the dark, and the amount of silver in TiO2/Ag nanocomposites (0.10-7% by weight) were investigated on the photocatalytic removal of metribuzin from artificial and real aqueous solutions.
Main results: Laboratory investigations showed that TiO2/Ag nanocomposite containing 10% by weight of silver, reaction time of 120 minutes, pH equal to 6, catalyst mass of 0.013 g, and initial concentration of 10 mg/L metribuzin are the best properties to maximize the removal of metribuzin in the presence of UV light. The obtained results showed that the synthesized TiO2/Ag nanocomposite has a higher potential in the degradation of herbicides compared to the commercial TiO2 nano-catalyst. In addition, the proposed method was used to remove metribuzin injected into the water of the Karun and Zohreh rivers and the wastewater of the sugarcane factory under optimal conditions, and successful results were obtained. Also, the results of using and regenerating the titanium dioxide/silver catalyst three times to remove metribuzin show the high efficiency of this photocatalyst in removing metribuzin from water samples. Comparing the methods available in the literature for the removal of metribuzin with the present method showed that the proposed method is better or comparable to the reported methods.
Fatemeh Ebrahimi Rad, Jafar Towfighi Darian, Saeed Soltanali,
Volume 6, Issue 2 (9-2022)
Abstract
Research Subject: In recent years, industrial-scale production of propylene based on oxidative dehydrogenation of propane has been of particular importance due to the lack of thermodynamic limitations. In this regard, the use of natural zeolites with high abundance and low price has placed a special position. In this research, perlite natural zeolites were treated with ionic liquid solution and acid, then supported vanadium catalysis were synthesized. Performance of catalysis were investigated in oxidative dehydrogenation of propane to propylene process with a mixed feed of propane and air in a fixed bed quartz reactor under condition of atmospheric pressure and temperature of 500˚C with a flow rate of 40000 h-1 (GHSV).
Research Approach: In this study, natural perlite support as a source of aluminum oxide (Al2O3) and silica (SiO2) was ion exchanged by one molar solution of ammonium nitrate (NH4NO3 1 M). Continuously, to investigate the effect of delamination, different acid molar concentrations of nitric acid (HNO3) equal to 0.75, 1.5, and 2.25 were used and then compared with the just modified ion exchange sample without acid leaching (V/PERLIT-I). Dry vanadium impregnation, as an active metal, was carried out to synthesize 8% wt. catalysts. X-ray diffraction analyzes (XRD), scanning electron microscopy (FE-SEM), and ammonia Temperature-programmed desorption program (NH3-TPD) were used to characterization and evaluate the properties of the catalyst.
Main Result: The results showed that the concentration of acid used affects the conversion and selectivity of the catalysis. In comparison, a significant difference was observed between the performance of V/PERLIT-I sample compared to V/PERLIT-IA samples. The maximum selectivity value for V/PERLIT-IA(2.25) was 74%. According to the results, the treated perlite support with suitable selectivity can be considered in the studies of use as an industrial support.
Mohammad Hosein Eghbal Ahmadi, Amir Mosayebi,
Volume 6, Issue 3 (12-2022)
Abstract
Subject
In this study, the steam reforming of the methanol process was analyzed based on three different inputs including temperature, pressure, and H2O/CH3OH ratio with the use of different Artificial Intelligence methods.
Methodology
In the first step, Cu-Zn/ZrO2 catalysts were synthesized via the co-precipitation method, and then experimental tests of steam reforming of methanol were performed at a temperature range of 180 –500 °C, the pressure of 1-11 bar, and the H2O/CH3OH ratio of 0.75-3.75 on the Cu-Zn/ZrO2 catalyst in a fixed bed reactor. Afterward, three different methods of Mamdani fuzzy type-1, Mamdani fuzzy type-2, and Sugeno fuzzy were applied in order to develop the models. Using these methods, the developed models only required the heuristics derived from the expert’s knowledge and some experimental data, without needing the calculation of complex kinetic as well as thermodynamic parameters related to the corresponding process. In addition, the structures of the developed fuzzy models were optimized to improve the model performance according to the analysis of the initial results. The model developments didn’t require a high number of experimental data, and this feature is especially interesting when dealing with the process conditions in which data gathering is expensive or the accuracy of data is low.
The main results
The overall accuracy as well as the properties of the developed models were compared. The type-2 Mamdani fuzzy model proved to be the best model, using which, the methanol conversion, H2 yield, and CO yield were predicted with accuracies of 67%, 91%, and 83%, respectively.
Meghdad Azimi, Saeed Tavangar, Seyed Ghorban Hosseini, Muhammad Eghdamtalab,
Volume 6, Issue 4 (12-2022)
Abstract
Abstract
Research subject: The pure Goethite nanoparticles were synthesized successfully with solution oxidation method and by using raw materials Iron (II) sulfate heptahydrate (FeSO4.7H2O) and sodium hydroxide (NaOH).
Research approach: In this study, the simulation of experiment was implemented by Minitab software, with complete factorial method, at 40°C, the variation of two parameters including the flow rate of entered gas in the solution reaction (Q) and mass percent ratio of raw materials (R) (mass percent of iron (II) sulphate to mass percent of sodium hydroxide), in two levels (Q=2 and 13.3 Lit/min) and (R=1 and 3) were evaluated. The qualitative analysis of results was performed by X-ray diffraction (XRD), synthesis of Goethite phase (α-FeOOH) confirmed Iron oxyhydroxide and the Energy-dispersive X-ray spectroscopy (EDX), illustrated that the synthesized Goethite has high purity percentage (≥99.8%). The field emission scanning electron microscopy (FESEM) for Goethite reported a bar-shaped crystal structure, with an average particle Cluster size between (23-43nm), based on R and Q and by analyzing the oxidation-reduction potential(ORP) results, it was seen that the reaction time of Goethite formation is between 635-2210s.
Main results: The statistical analysis of results with Minitab software can create Correlation relations for Goethite, between two parameters(Q and R) and two response (reaction time(t) and average particle Cluster size(d)) at the temperature of reaction solution 40°C. regarding the relations, it was seen that at the temperature of reaction solution 40°C, with an increase in air flow rate(Q) and decrease of the mass percent ratio of raw materials(R), the reaction time and average particles Cluster size of Goethite decrease generally and vice versatile. Also, the percentage change (R) has a higher impact on average particles Cluster size and reaction time than changes (Q).
Mahdi Sedighi,
Volume 6, Issue 4 (12-2022)
Abstract
Research Subject: The conversion of carbon dioxide into hydrocarbons is a potential process that can reduce and control greenhouse gases. According to the United Nations Development Program's sustainable development goals, liquefied gas is an environmentally friendly fuel. Hydrogenation of carbon dioxide over a suitable catalyst can be used directly to synthesize light hydrocarbons.
Research Approach: This study investigated the direct synthesis of liquefied petroleum gas from carbon dioxide hydrogenation using SBA-15 catalyst modified with copper and zinc nanoparticles. In this study, hydrogen and carbon dioxide were used as reactant gases, and the operation conditions such as reaction temperature and residence time were evaluated.
Main Results: The results showed that by modifying the catalyst with copper and zinc active sites, the active surface of the catalyst was reduced to 542 m2.g-1. Furthermore, SEM results revealed that the addition of metal oxides ZnO and CuO resulted in uniform distribution in the internal channels of the 1Cu1Zn/SBA-15 catalyst, with no aggregation. LPG production is optimal at a temperature of 360 oC and a residence time of 10 g.h.mol-1. These conditions yielded a CO2 conversion rate of 24.6% and a LPG selectivity of 64.8%, respectively. The amount of LPG produced increases as the temperature rises, and after reaching the optimum temperature, there is no significant increase in the amount of LPG produced. The percentage of CO2 conversion does not change much when the residence time is increased after the optimum value, indicating that the reaction has reached its thermodynamic theoretical range. According to the catalytic lifetime test of 1Cu1Zn/SBA-15, CO2 conversion percentage and LPG selectivity do not change after 85 hours. Based on the results of the experiments, the synthesized catalyst can hydrogenate CO2 efficiently to LPG.
Parya Torkaman, Ramin Karimzadeh, Arezou Jafari,
Volume 7, Issue 1 (7-2023)
Abstract
Research subject: Electromagnetic heating is one of the new methods of upgrading and increasing heavy oil extraction. In this method, electromagnetic waves will increase temperature, break heavy compounds, reduce viscosity, and improve and increase oil recovery.
Research approach: In this research, magnetic iron oxide nanoparticles (Fe3O4) were synthesized by the co-precipitation method, and the efficiency of these nanoparticles in the process of electromagnetic heating and heavy oil upgrading was investigated. Also, a comparison was made between the effect of these nanoparticles in the process of electromagnetic heating and activated carbon. In this process, oil samples containing 0.1% of Fe3O4 nanoparticles or activated carbon were irradiated with microwave (frequency 2.54 GHz and power 400 W) for 0 to 8 minutes, and the temperature and viscosity variation were investigated.
Main results: The results showed that microwave radiation increased the temperature of the samples. The temperature of the sample of crude oil, crude oil with activated carbon, and crude oil with Fe3O4 nanoparticles increased from ambient temperature to 70, 82, and 90°C, respectively, under wave radiation for 8 minutes. Also, the most significant decrease in viscosity was reported in 4 minutes: the viscosity of crude oil sample, crude oil with activated carbon, and crude oil with Fe3O4 nanoparticles under wave irradiation for 4 minutes decreased 295 mP.a to 261, 254, and 223 mP.a, respectively. In other words, the viscosity of the samples under wave irradiation for 4 minutes for crude oil, crude oil with activated carbon, and crude oil with Fe3O4 nanoparticles decreased by 11.5, 13.9 and 24.4%, respectively.
Hamid Karami, Saeed Soltanali, Ali Abbasi, Elham Yaghoobpour,
Volume 7, Issue 2 (9-2023)
Abstract
Research subject: Propylene is one of the most prominent gases due to some valuable products and derivatives such as polymers, solvents, dyes, etc., which makes it one of the most important building blocks in the chemical industry. Due to the limitations of steam cracking and fluid catalytic cracking processes in terms of low selectivity, energy consumption, and significant CO2 emission, these processes cannot fulfill the growing demand for propylene. In recent decades, the dehydrogenation of light alkanes to produce light olefins, especially propane dehydrogenation (PDH), has attracted much attention. Pt-Sn and CrOx catalysts, which are widely used in this process, have good dehydrogenation activity and selectivity; However, the limitations of price, deactivation, and environmental problems are serious and have led researchers to improve coking stability, sintering Pt catalysts, and find new and environmentally friendly catalysts.
Research approach: : One of the challenging issues in the PDH process is achieving
appropriate catalyst. Several solutions, including modification of the base and introduction of additives, have been proposed to enhance the catalytic performance overcome the problems, and increase the resistant stability of Pt, Cr catalysts. Understanding the structure-performance relationship of catalysts during the PDH reaction is essential to achieve innovation in new high-performance catalysts. This research aims to introduce the characteristics of the dehydrogenation reaction, the progress made in the development of the catalyst, and the existing challenges. This research provides a deep understanding of the reaction mechanism and its role in the development and future directions of the catalyst for practical and industrial development.
Main results: This study offers a detailed understanding of how the reaction mechanism works and its significance in the development and future directions of the catalyst for practical and industrial advancement.
Shahnaz Khademizadeh, Maryam Aghaei, Roghayeh Ghazavi,
Volume 7, Issue 4 (12-2023)
Abstract
Research subject: The present study was conducted with the aim of investigating the degree of compatibility of research topics in the field of chemical engineering in Shahid Chamran University of Ahvaz with Iran and the world. Also, prominent engineering issues in the field of chemistry have been identified.
Research approach: The research is considered a type of scientometric applied studies. The statistical population is made up of researches related to the field of chemical engineering in the Web of Science database. Taking into account the key words of sources that were extracted from the Web of Science database, the information was transferred to the PreMap program and by applying restrictions, the terms were unified for all three files of the world, Iran and Shahid Chamran University of Ahvaz. In order to check the thematic alignment, the clustering method was done with VOSviewer software. The index of structural similarity of subjects has also been used to determine the level of research alignment.
Main results:The researchers have searched for the subject areas of the chemical engineering department in Shahid Chamran University, Iran and the world. With the percentage of structural similarity, it was found that over time, the subjects of chemical engineering in Shahid Chamran University have aligned with Iran and the world, as well as Iran with the world, but the percentage of alignment with the world is low. To increase the alignment of chemical engineering subjects, platforms for sharing information and learning can be created for students, professors, researchers and experts in the field of chemical engineering. Also, a comprehensive approach to monitoring and evaluating research processes, including their alignment with leading research institutions, can provide research policymakers with valuable insights to improve research policies and foster scientific and technological innovation.