البحث — المستودع الرقمي العراقي

نتائج البحث: 25 من أصل 158

فعالية عامل مساعد محضر ومحفز بمعادن مختلفة لعملية ازالة الكبريت بالهدرجة لزيت الغاز العراقي == Activity of A Prepared Catalyst Promoted By Different Metals For The Hydrodesulfurization of Iraqi Gas Oil

اسم المؤلف: طارق محمد نايف

اسم المشرف: Abdul | Halim A.K. Mohammed | Hussein K. Hussein

الموضوع العام: الهندسة الكيمياوية

السنة: 2014

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: دكتوراه

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: The present work deals with the improvement of Iraqi gas oil containing 1.402 wt. % sulfur by hydrotreating process using different prepared hydrodesulfurization catalysts (Ni - Mo/? - Al2O3, Co - Mo/? - Al2O3, Co - Ni - Mo/? - Al2O3, Ti - Ni - Mo/? - Al2O3 and Re - Ni - Mo/? - Al2O3). All catalysts were prepared under vacuum impregnation to ensure efficient precipitation of metals within the carrier ? - Al2O3. Physical adsorption by nitrogen was investigated, and used for determination of the surface area and pore size distribution of prepared catalysts.The results showed that modified catalysts Ti - Ni - Mo/? - Al2O3 and Re - Ni - Mo/? - Al2O3 have a high surface area 225.1 and 235.23 m2/g respectively, as compered with conventional prepared catalysts Ni - Mo/? - Al2O3 and Co - Mo/? - Al2O3 which their have surface area 178.5 and 191.4 m2/g respectively, and exhibits behavior of type four according to Brunauer, Emmett and Teller (BET) classification, and type H1 according to de Boer classification for hysteresis loop, so, it was concluded that the pores of these catalysts are cylindrical. The performances of all the synthesized catalysts for removal of sulfur and aromatic saturation gas oil were tested at different LHSV (1 to 4 h - 1), temperatures ( 275 to 350 °C), constant pressure 40 bar, and H2/HC ratio 500 ml/ml. The results showed that the sulfur and aromatic content were decresed at all operating conditions for all prepared catalysts. It was found that the sulfur removal from gas oil increases with temperature and decreasing with the space velocity, and the temperature has higher effect on the process of sulfur removal than the space velocity. It was found also that Ni - Mo/? - Al2O3 catalyst is slightly better in sulfur removal (61.5 wt. % ) with than Co - Mo/? - Al2O3 (59.2 wt. %) at the same operation conditions (350 °C and LHSV 1 h - 1), and hydrodesulfurization over Ni - Mo/Al2O3 was improved remarkly by adding Ti and Re promoters. Maximam sulfur removal was 76.81 wt. % using Re - Ni - Mo/? - Al2O3 at temperature 350?C, LHSV 1 h - 1, while minumum aromatic content value is 15.44 wt. % for Ni - Mo/ ? - Al2O3. Calculations showed that the hydrodesulfurization rate expressions fitted with second order reaction kinetics model.The rate constant varied from 0.005 to 0.144 liter/kg.h and the values of activation energy varied from 50.0 to 93.59 kJ/mole for all prepared catalysts. Thiele modulus, for all prepared catalysts was calculated.The lower values of the Thiele modulus (> 0.4) gives strong evidence of negligible pore diffusion limitation.

تثبيط تاكل الحديد الكاربوني الواطئ في حامض الكبريتيك باستعمال كحول البولي فينيل ومستخلص نبات PIPER LONGUM == Corrosion Inhibition of Low Carbon Steel In Sulfuric Acid By PVA And Piper Longum Extracts

اسم المؤلف: اياد بهاء الدين احمد

اسم المشرف: ماجد ابراهيم عبد الوهاب | ابرائيل سركيس يارو

الموضوع العام: الهندسة الكيمياوية

السنة: 2014

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: دكتوراه

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: The inhibitive power of Polyvinyl Alcohol (PVA) and the synergistic effects added on the inhibition power of PVA by two types of Piper Longum (PL) Ethanol Extracts (PLEXT) were investigated toward the corrosion of carbon steel in (0.2N) H2SO4 solution in the temperature range (30 - 60?C) and PVA concentration range (150 - 2000 PPM).The corrosion rate measurements were carried out using the following two standard corrosion measurements techniques.1. Weight loss technique was applied on carbon steel plates to evaluate inhibition efficiency in presence and absence of these inhibitors.2. Electrochemical Techniques were used to validate and support inhibition efficiencies found in weight loss techniques.A detailed study of the experimental methods and results is reported for each test conducted.The weight loss results showed that PVA could serve as a corrosion inhibitor but its inhibition power was found to be low for the corrosion of carbon steel in the acidic media.It was shown that the inhibition efficiency for (PVA) decreased with increasing temperature at a given PVA concentration. On the other hand it was shown that at given temperature the inhibition efficiency of (PVA) was increased with increasing of PVA concentration until a PVA concentration of 2000 ppm PVA was reached then only a slight decrease in inhibition efficiency was observed when increasing PVA concentration further.The Maximum inhibition efficiency reached was about 71 % at 30?C & 2000 ppm (PVA) concentration, calculated by the weight loss techniques.In order to improve the inhibition efficiency of PVA, by adding 6 ml/l of ethanol extracts of piper longum (PL) to a liter of the acid solution in presence of concentrations of PVA 150,500,1000.1500, and 2000 ppm at temperatures (30,40,50, and 60?C) was investigated.Weight loss results showed a jump in inhibition efficiency (% IE) value of the modified inhibitor mixture compared with the presence of PVA alone at all (PVA) concentrations for temperature range considered in this investigation.This study demonstrated the extra inhibition power added by the (PL) fruit extracts to the organic polymer (PVA) used. Maximum inhibition efficiencies recorded were approximately 95% for Piper Longum Extract Number two (PLEXT2) at 30?C and 2000 ppm PVA.The kinetic and thermodynamic parameters regarding the adsorption process of inhibitors used was calculated.It was found that the changes corrosion rates correlates well with the Arrhenius equation in absence and presence of inhibitors.The Results showed that the adsorption of the polymer and the plant extract follows Langmuir adsorption isotherms and the adsorption of the inhibitor molecules on the metal surface is mainly physical, nevertheless the adsorption is believed to be slightly deviated from the Langmuir model at 30?C.Electrochemical analysis of the corrosion process of carbon steel in an electrochemical corrosion cell was investigated using 3 - Electrode corrosion cell coupled with a potentiostat interfaced with a computer which assisted polarization data interception and interpretation.Polarization technique was used to obtain polarization data which was recorded for carbon steel in 0.2N H2SO4 solutions in presence and absence of the inhibitors investigated. Electrochemical runs were done in the (PVA) concentrations of 150, 1000, and 2000 PPM and a temperatures of 30, 40, 50, and 60?C.Tafel slopes, Corrosion currents, and corrosion rates were calculated from polarization curves by Tafel extrapolation method. Results showed corrosion rate trends similar to findings by the weight loss method. It was indicated also that the corrosion of carbon steel in 0.2N H2SO4 is highly activity controlled.Results revealed that the inhibition action is occurring at both anodic and cathodic sites on the metal surface so that both corrosion reactions were affected, so that the composite inhibitor could be considered as mixed - type inhibitor.Electrochemical results confirmed that (PLEXT2) was more efficient as inhibition improvement additive to (PVA) than (PLEXT1) at all experimental conditions range encountered in this study.The highest inhibition efficiency recorded using Tafel polarization method was 83% obtained at 30?C and 2000 ppm of PVA with 6 ml/l PLEXT2.

ازالة الكادميوم من المياه الملوثة بالترسيب الكهروكيمياوي باستخدام حزمة من الانابيب الفولاذية متحدة المركز == Removal of Cadmium From Wastewater By Electro - Deposition On Stainless Steel Concentric Tubes Bundle

اسم المؤلف: انس بديوي سلمان

اسم المشرف: عباس حميد سليمون | بسمة عباس عبد المجيد

الموضوع العام: الهندسة الكيمياوية

الموضوع الدقيق: الهندسة الكيمياوية

الدرجة: دكتوراه

الجامعة: جامعة بغداد - كلية الهندسة - قسم الهندسة الكيمياوية

اللغة: الانكليزية

مكان الجامعة: بغداد

الصفحات الاولى:

المستخلص: تم دراسة انتقال الكتلة الخاص بايونات الكادميوم الثنائية الى سطح اسطوانة دوراة مصنوعة من مادة الفولاذ المقاوم للتاكل (كقطب كاثود) بواسطة قياس التيار المحدد لتفاعل اختزال ايونات الكادميوم الكاثودي في محلول كبريتات الصوديوم بتركيز مولار باستخدام خلية ثلاثية | 1 - Mass transfer of Cd+2 ions to a smooth stainless steel rotating cylinder electrode was studied by measuring the limiting current for the cathodic reduction of Cd+2 in 0.5 M sodium sulphate supporting electrolyte by three electrodes cell with stainless steel rotating cylinder electrode working in hydrodynamic voltammetry mode. The studied parameters were electrolyte pH (4, 5, 6 and 7), initial Cd+2 concentrations (50, 100, 200, 300 and 400 ppm) and rotation rates (100, 150, 200 and 250 rpm). Cadmium ions' reduction potential for mass transfer control conditions was found to be - 0.13 V. Diffusion coefficient was determined and correlated with the bulk concentration of Cd+2 in sodium sulphate solution. The increase in pH was found to enhance the mass transfer coefficient and this effect diminishes nearly at pH=7, and the experimental data were well fitted by an empirical dimensionless correlation among the Sherwood number, Reynolds number and Schmidt number. The obtained correlation was : Sh=0.047 ?Re?^0.769 ?Sc?^0.356 For (8015.519 < Re < 20587.07) Reduction potential obtained via the voltammograms constructed by the rotating cylinder cell was applied for the two pilot scale units in order to keep the process under mass transfer control conditions. Parameters studied in these units are : initial cadmium concentration, pH, and electrolyte flow rate. The first pilot scale unit was an electrochemical reactor with smooth stainless steel concentric tubes, and the second one was an electrochemical reactor with stainless steel mesh concentric cylinders.2 - For the stainless steel smooth concentric tubes cathode, mass transfer coefficient was calculated and correlated with initial concentration.Effect of pH on mass transfer coefficient was studied and correlated, and it was found that the effect of pH was found to be completely negligible at pH=7.On the other hand, effect of flow rate on mass transfer coefficient was studied and correlated. Performance of the reactor was analyzed by introducing figures of merit for fractional conversion, specific energy consumption, space time yield and normalizes space velocity. The experimental data were correlated in a dimensionless expression as flows : Sh=0.804?Re?^0.632 ?Sc?^(1/3) For 254 < Re < 1018.3 - For the stainless steel mesh concentric cylinders was adjusted to work under mass transfer control conditions by applying the reduction potential obtained in hydrodynamic voltammetry experiments.Effect of initial cadmium concentration, pH and solution flow rate was studied and analyzed. Mass transfer coefficient was correlated with these studied parameters.Similar to smooth cathode, the mesh cathode showed a negligible response to pH at pH=7.Noticeable enhancement in mass transfer coefficient was investigated by the action of flow rate, and the mass transfer coefficient was correlated with the solution flow rate.The mesh cathode showed a higher conversion than that adopted by the smooth cathode, and showed lower cumulative current efficiency than that of smooth cathode.Mesh cathode showed specific energy consumption, space time yield and normalized space velocity higher than that for the smooth cathode.Experimental data for the mesh reactor were correlated in a dimensionless relation as follows : Sh=1.898?Re?^0.514 ?Sc?^(1/3) For 235 < Re < 943 Cadmium ions reduction reaction was found to follow a first order reaction with respect to Cd+2 concentration, and reaction rate constant was predicted under different operating conditions.