مجله فرآیند نو
پیاپی 83 (پاییز 1402)

In this study, hydrogen production from glycerol steam reforming (GSR) has been investigated as a renewable source of energy. Exergy-related balance was done for all simulation points, and carbon dioxide emission intensity and hydrogen production intensity were also calculated for the presented process. The simulation results showed that the hydrogen production intensity in the GSR process was equal to 3.92 kmole H2/kmole feed, which is in a good place compared to conventional processes. Exergy analysis showed that the total exergy destruction of the GSR process is equal to 24755.871 kW, among which, the glycerol steam reformer has the highest exergy destruction rate with a share of 97.18%. Based on the environmental assessment, in total, the GSR process emits carbon dioxide equivalent to 24.45 tons/h, and the share of emissions for process flows, utility and feed is 96.59, 3.414 and 0.00 percent, respectively.

Removing sulfur and sulfur compounds from liquid fuel is one of the most important research topics. In this research, activated carbon was prepared by chemical activation from walnut shells, then modified by iron nanostructure and chitosan separately and together, and used to remove dibenzothiophene from isooctane fuel. BET, EDX-SEM, and FTIR analyses were used to investigate the adsorbent. Equilibrium experiments showed that the adsorption process is a single layer, and the maximum adsorption capacity is 285.71 and 178.57 mg of dibenzothiophene per gram of adsorbent modified by iron nanostructure and per gram of adsorbent modified by iron nanostructure and chitosan, respectively. The results of kinetic data showed that the pseudo-second-order kinetic model is consistent with the experimental result. To determine mass transfer parameters, the mathematical model of film-pore-surface diffusion model was used by MATLAB software and it was observed that external mass transfer and pore diffusion stages are more important.

Considering the water quality problems and the strict laws established for drinking water treatment, the need to use more effective and economical methods to remove water pollutants is felt. Meanwhile, the use of membrane processes is considered one of the most important methods to remove pollutants as best as possible. Based on this, in the current research, microporous polyvinyl chloride (PVC) membranes containing titanium dioxide (TiO2) nanoparticles were made using the nonsolvent induction phase separation method for use in humic acid separation as a model of polluted water. The obtained results showed that the membrane containing 3 wt% of nanoparticles has the highest pure water permeability with a value of 146.2 l/m2h. Also, the analysis of the results of humic acid rejection showed that the membrane with 2 wt% of nanoparticles with the smallest average radius of the surface pores had the highest separation efficiency with a value of 80%.

One of the main objectives of refineries is to produce high-quality gasoline while respecting environmental standards. Accordingly, the normal hexane hydroisomerization and the preparation of appropriate catalysts for this process still pose a challenge in refineries. Therefore, in this work, heteropoly phosphotungstic acid (HPW), which contains high BrØnsted acid sites, and the metal-organic framework UiO-66 were synthesized. Then, HPW/UiO-66 and (Pd+Pt)/HPW/UiO-66 samples were prepared by impregnation method to improve the stability of the catalyst. Finally, by adding platinum and palladium nanoparticles as promoters, the progress of the performance and activity of the catalyst in the normal hexane hydroisomerization was investigated. In addition, the characteristics of the synthesized samples were determined by XRD, FE-SEM, N2 adsorption/ desorption, and NH3-TPD analyses. Accordingly, in the presence of the bifunctional catalyst (0.2%Pd+0.3%Pt)/50%HPW/UiO-66, the selectivity of iso-hexane and the normal hexane conversion were obtained at 77.4 and 60%, respectively, after 36 h of reaction time.

Hydrocarbon fouling of preheat exchangers causes several detrimental impacts on operation, environment, safety, as well as economy of oil refineries. To investigate threshold fouling models, a variety of hydrocarbon fouling data, such as temperature, oil flow, fluid properties, and geometries of such exchangers, has been gathered from the literature. The most accurate models for predicting the fouling rate are the Polley, Ebert, and Panchal models, with slopes of 0.352, 0.108, and 0.022, respectively, based on fitted curves on the computational fouling rates in terms of comparable experimental values. The sensitivity analysis indicates that the two factors that profoundly affect the fouling rate are the surface temperature and Reynolds number. Using the Polley's equation, the fouling rate in preheat exchangers may be predicted with the highest degree of accuracy, mean sensitivity analysis of 0.29, based on the consistency of calculated and experimental data.

The Automotive exhaust emission is the predominant source of air pollution. With the increasingly stringent environmental protection requirements, the standards of gasoline are constantly upgrading via reducing the content of olefins, sulfur and aromatics. Alkylation of isobutane with butene is one of the most important ways for production of gasoline with high octane number. Although, the isobutane with olefins alkylation refinery process based on liquid acid catalysts such as sulfuric acid and hydrofluoric acid has been commercially successful but the use of these catalysts in the process of alkylation has environmental, health and high operatin costs problems. Solid acid catalysts especially zeolites due to their high operability and lower cost of equipment, no environmental problems and outstanding structural properties, are more suitable candidates for improving the isobutane/butene process. So, replacing these catalysts with solid acid catalysts is one of the most important research goals in the field of catalysts.