Sharif Digital Repository

Long-term deactivation of a commercial K-promoted Fe2O3 catalyst used in the dehydrogenation of ethylbenzene to styrene monomer was studied using thirty months of operating data of three industrial SM radial fixed bed adiabatic reactors. The Langmuir-Hinshelwood, Hougen-Watson model (LHHW) was used for reaction kinetics modeling. The kinetics of coking from ethylbenzene and styrene and the short-term deactivation function due to the quick coke formation were also considered in the model. The kinetics of long-term deactivation of the catalyst for ethylbenzene dehydrogenation to styrene between 550 and 630 °C were determined by allowing the effects of temperature and time on the catalyst... 

Biodegradation is an effective method for removal of hazardous organic compounds such as styrene and ethylbenzene from petrochemical wastewaters. Although using this method for wastewater treatment meets (satisfies) the industrial standards, still these methods have significant disadvantages. Active sludge systems can not be effective enough due to the volatility and recalcitrance of styrene and ethylbenzene and a significant amount of volatile organic compounds exists in the discharging air. In order to reduce or totally remove this amount of pollutants in the discharging air, Membrane Bioreactors are used. One of the main problems of these systems is membrane fouling. In this thesis the... 

In this study as representatives of alkenylbenzenes and mono-alkylbenzenes respectively were considered individually and as binary mixtures. It was observed that styrene, and ethyl benzene were inhibitory types of substrates across the tested concentration ranges. Thus, biodegradation kinetic is well described by the Haldane model. Kinetic parameter's assessments from single substrate degradation tests and these parameters were used to predict possibly interaction factors achieved from dual substrate experiments. The achieved outcomes from mixture of experiments revealed that the ratio of depletion for each substrate is affected by the presence of the other. It was also inferred that ethyl... 

Suspension polymerization is an important industrial process. Product of this process is particulate polymers that have a widely use in human lives. An important property of suspension polymerization process is the particle size distribution (PSD), which affects the end-use properties of the products. Therefore, the evolution of PSD is a major concern in the design of a suspension polymerization process. In a suspension polymerization reactor the evaluation of particle size distribution is the result of the interaction of the mixing conditions and the kinetics of the polymerization reactions. Mathematical modeling of particle size distribution in suspension polymerization processes should... 

The purpose of this project is to design a water-based drilling fluid for use in high-pressure and high-pressure conditions (Deep Drilling). This goal is usually achieved by adding the resistant polymers to the ambient conditions (temperature stability) to the drilling fluid (here the blue base fluid), and then the rheological properties of the fluid are studied. The stability of the rheological properties of the fluid in high temperature and high pressure conditions is not constant. In this situation, a sequence of events occurs, for example, decreases with increasing viscosity and turbulence, and hence the reduction of drilling fractures and the efficiency of the bottom of the well is... 

Emulsion polymerization is a multiphase process which produces dispersions of polymeric particles in water called polymeric latexes. When instead of surfactants solid particles stabilize the latex, the process is called Pickering emulsion polymerization. Latexes produced in this way exhibit better mechanical and optical properties. In this work, a model for styrene Pickering emulsion polymerization in the presence of Laponite RDS given in the literature was simulated. The results of simulation were unsatisfactory. A procedure was developed to separately check different parts of the code which was written for the task. Also, another emulsion polymerization system, in which the monomer was... 

Polymer flooding is a widely applied technique for enhanced oil recovery (EOR), yet conventional polymers such as hydrolyzed polyacrylamide and xanthan gum are limited by biodegradation, salinity sensitivity, and thermal instability. Incorporating hydrophobic groups into the polymer backbone is a promising strategy to overcome these challenges. In this study, acrylamide–styrene–maleic anhydride terpolymers with different molar ratios (98/1/1, 90/2/8, 90/5/5 and 90/8/2) were synthesized and characterized by FTIR, HNMR, and TGA. The rheological behavior of the polymer solutions was examined using a rotational viscometer, and their influence on carbonate rock wettability was evaluated through... 

The use of polymers in the EOR process is very common. Most of these polymers are sensitivity to temperature, salt, and the presence of bacteria. Among these materials, hydrolyzed polyacrylamide (HPAM) is the most widely used. Due to the sensitivity of HPAM in harsh conditions like temperature and salinity of the environment, modification of this polymer by hydrophobic groups can be very effective. Hydrophobic-hydrophilic associative polymers have shown unique rheological properties and high thermal stability, which is due to the presence of a small percentage (up to two percent) of hydrophobic monomers in their structure. Despite these excellent properties for acrylamide copolymers... 

This thesis presents the synthesis of terpolymers composed of acrylamide (AM), styrene (St), and maleic anhydride (MAH) monomers, utilizing varying concentrations of the reaction components. The synthesis was conducted via inverse emulsion of water in cyclohexane (20/100), employing AIBN as initiator and Span80 as a surfactant. Various analytical techniques, including FTIR, NMR, SEM, viscometry, DLS, GPC, EA, EDS were performed on the samples. Additionally, the impact of polymer addition in water on the reduction of pressure drop was evaluated. Acrylamide is an inexpensive and water-soluble monomer that serves as a primary building block for producing high molecular weight polymers that are... 

Viscosifiers or thickeners are responsible for regulating the rheological properties of fluids to control flow and are widely used in various industries. Polyacrylamides modified with hydrophobic groups are among the most important viscosifiers in various industries, which are mainly produced by two methods: inverse emulsion polymerization and micellar polymerization. The aim of this study is to compare the two mentioned polymerization methods for the synthesis of polyacrylamides modified with hydrophobic groups with acrylamide monomers (main monomer), styrene (water-repellent monomer) and maleic anhydride (hydrophilic auxiliary monomer) and also to compare the effect of using two different...