نشریه پژوهش های کاربردی مهندسی شیمی - پلیمر
سال ششم شماره 4 (پیاپی 22، زمستان 1401)

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.

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).

Research subject: 

In this research, the synthesis method of phenol-formaldehyde resin has been investigated, which can be used in the wood and chipboard industry. This resin is prepared in two forms, Novolac and Resole, which different products are formed by changing the reaction conditions. Resole is used as a liquid adhesive in the wood and chipboard industry.

Research approach: 

 Various parameters are effective in the synthesis of the resin and the properties of the final product such as the molar ratio of formaldehyde to phenol, the pH of the reaction medium, the temperature and time of the reaction, and the amount of water released from the reaction. The synthesis of this material was carried out under reaction conditions with the molar ratio of formaldehyde to phenol from 1.84 to 2.50, the reaction medium pH from 4.0 to 10.85, the reaction temperature from 80 to 100 ◦C, the reaction time from 0.5 to 4 h, and the water output amount in the term of dehydration dimensionless number from 0.18 to 1.02.

The results showed that the maximum product stability time was obtained for 18 days at the molar ratio of 2, the alkaline medium at pH 9 to 10, the reaction temperature at 90 to 95 ◦C, and reaction time at 2 h. Moreover, viscosity, density, gelation time, and percentage of solids were obtained 180 cP, 1.224 g/cm3, 30 S, and 51.20%, respectively. Product properties were optimized by adding diethylene glycol and urea. The stability time increased to 105 days by adding 8% diethylene glycol and the free formaldehyde amount in the product decreased to 1.29% by adding 4% urea. According to the properties of the created product, the obtained reaction conditions can be used for the mass production of the resin.

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.

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.

Research subject:

The kinetics of xylene isomerization reaction on Mo-Pt @ZSM5 catalyst has not been investigated so far. In this research, the single reversible reaction of meta-xylene to para-xylene has been studied to model this process. Considering that the feed of the industrial unit has only small amounts of non-xylene compounds, it seems reasonable regardless of other reactions and the results of this research also confirm it.

Research approach:

The desired reaction was carried out in the gas phase and constant temperatures of 375 oC and 378 oC on Mo-Pt @ZSM5 catalyst. The feed is taken from an industrial unit. In each test, the temperature is considered constant. In this research, in order to obtain a simple model, only the reversible reaction of meta-xylene to para-xylene is considered. The forward speed constant is considered as an adjustable parameter, and the backward reaction speed constant is calculated from the (meta-xylene)-(para-xylene) equilibrium constant reported in the literature. Since other reactions are neglected, the total mole fraction of meta-xylene and para-xylene is assumed to be constant and equal to their sum in the feed, and the mole fraction of ortho-xylene is calculated from the (meta-xylene)-(ortho-xylene) equilibrium constant reported in the literature. Using the mass balance and performance equation of the packed column as well as Ergun's equation to estimate the pressure changes along the column, a suitable differential equation system was proposed in this research and solved numerically using the ode45 function in MATLAB.

both the experimental data and the simulation results with the Aspen HYSYS software show that the temperature has little effect on the obtained results in the investigated temperature range. The optimal value of the reaction rate constant of metaxylene to paraxylene for the forward reaction is 1340 cm3 of product per gram of catalyst per hour. For the reverse reaction, it is obtained from the equilibrium constant data in terms of temperature. The results and the proposed simple kinetic model give a good prediction of the experimental data.

Petroleum coke calcination is a chemical process during which the petroleum coke loses moisture and volatile combustible materials due to the increase in temperature and ultimately improves the physical properties of the calcined coke. In this study, A 2-Dim model was developed for the petroleum coke calcination process via rotary kiln using the CFD approach. Understanding the temperature, concentration, and fluid movement behavior are the main goals for developing the simulation model, by using which the rotary kiln control and design can be performed.

Comsol Multiphysics was applied to develop the simulation model. Petroleum coke rotary kiln calcination consists of two solid and gas phases, which cross each other counter-currently. All governing physics in the system, including chemical reactions, heat transfer via conduction, convection, and radiation, intra-phase and interphase mass transfer, evaporation or evolution of components from the solid phase into the gas phase, fluid turbulency and all complex relationships were considered. Using the finite element method, the governing equations of the model were solved, and consequently, the variation of temperature, components concentration, and fluid velocity was calculated.

It is concluded that tertiary air injection significantly affects the temperature profile and combustion reactions in the bed (About 100 degrees increase in temperature). In addition, the maximum temperature of 1910 °C has been achieved in the kiln. Concentration changes of components in the gas phase were also seen mainly in the bed entrance and in the areas near the tertiary air injection. Comparing the results with similar works showed the high accuracy of the developed model

Research topic: One of the new methods in the processes of increasing oil recovery from hydrocarbon reservoirs is the method of using ultrasonic waves. In this research, using ultrasonic waves and their application in a large-scale sample tank, its effect on increasing oil extraction by the numerical method is investigated.

In this research, the modeling process has been performed using MATLAB software. First, by determining the porous environment, the amount of pressure increases due to ultrasonic waves due to solving the sound equations (Helmholtz) by MATLAB k-waves toolbox is investigated. Finally, considering the cumulative production at a specific time from the production well and determining the oil recovery from the reservoir in the presence of a wave, to examine the effect of well location parameters and its distance from the wave generation source, wave production starts time, wave application methods (Pulsed and continuous), is performed at an optimal frequency and power.

According to the modeling results, the closer the wave start time is to the first days of production, the higher the oil recovery rate; So that by starting the application of ultrasonic wave under the power of 5 kW and frequency 20 kHz simultaneously with the production of well oil from the first day, oil recovery compared to oil recovery in the case of starting the wave from the fifty and ninety days, respectively 4/5% and 8% more. Oil recovery is 1.8% higher if the wave is applied continuously to the reservoir at a given time than when pulsed at the same time. The modeling results show that the shorter the distance between the wave source and the production well, the lower the pressure drop in the reservoir area and the higher the oil recovery. According to the results, if the source of wave production is located at a distance of 200 feet from the production well, it will increase by 7.1% compared to the distance of 1800 feet from the oil recovery well.