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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.

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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 R² 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.

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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.

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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.

 

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