Materials Science
Aymen F. Zween; Zaidoon M. Shakor; Bashir Y. Sherhan
Abstract
Recycling residue hydrodesulfurization (HDS) catalysts is essential due to frequent deactivation. Petroleum coke's high ignition temperature and complex combustion behavior stem from its graphite-like structure and low volatile matter. This study investigates petroleum coke combustion and oxidation kinetics ...
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Recycling residue hydrodesulfurization (HDS) catalysts is essential due to frequent deactivation. Petroleum coke's high ignition temperature and complex combustion behavior stem from its graphite-like structure and low volatile matter. This study investigates petroleum coke combustion and oxidation kinetics with metal catalysts. Data from HDS catalysts (5% Co-10% Mo/active kaolin and 5% Co-10% Mo/active bentonite) are crucial for industrial regenerator simulations. Iraqi mineral clays, treated and loaded with cobalt and molybdenum, were used in HDS reactions of Iraqi gas oil with 10200 ppm sulfur at 360°C, 12 bar, and WHSV of 2 h⁻¹. Spent catalysts, coated with coke, were analyzed, and coke was removed using thermogravimetric analysis (TGA) at heating rates of 2.5, 5, and 10°C/min. MATLAB software assessed coke accumulation's impact on combustion activation energy via model-free and model-based methods. Activation energies for coke combustion were 46.48, 87.71, and 102.68 kJ/mol for hydrocarbons, soft coke, and hard coke, respectively, on 5% Co-10% Mo/active kaolin, and 41.98, 68.11, and 100.38 kJ/mol for 5% Co-10% Mo/active bentonite. TGA revealed 7.553% and 7.977% total weight loss in kaolin and bentonite catalysts. The model-based method was most effective for regenerating aged HDS catalysts at 850°C, especially for hard coke removal. DTG analysis showed two concavities, indicating soft coke below 350°C and hard coke between 350 and 850°C. For 5%Co-10%Mo/kaolin catalysts, peak temperatures (Tpeak) were 517, 526, and 610°C at heating rates of 2.5, 5, and 10°C/min. Bentonite catalysts showed lower Tpeak values.
Materials Science
Safa Luay Jasim; Shihab A. Zaidan; Enas Muhi Hadi
Abstract
Refractory ceramics were produced using silicon carbide (SiC) as the main component in combination with different weight percentages of Iraqi white kaolin (20%, 40%, 60% and 80%). Two different weight percentages of alumina (5% and 10%) were then added to each SiC-kaolin mixture. The samples were effectively ...
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Refractory ceramics were produced using silicon carbide (SiC) as the main component in combination with different weight percentages of Iraqi white kaolin (20%, 40%, 60% and 80%). Two different weight percentages of alumina (5% and 10%) were then added to each SiC-kaolin mixture. The samples were effectively mixed, molded, dried and fired at 1300 °C. The structural and physical properties were measured, including X-ray diffraction, apparent porosity, water absorption and thermal conductivity. X-ray diffraction showed that the addition of Al2O3 to the SiC-kaolin composite increased the mullite phase by interacting with the excess silica formed during the firing of kaolin or with the silica formed during the oxidation of SiC. The increase in kaolin content in the composite without alumina was accompanied by a decrease in physical properties, as the apparent porosity decreased from 30.17% to 17.95% and the water absorption from 16.31% to 7.07%. The addition of 80 wt.% kaolin led to a decrease in thermal conductivity from 35 to 15 W/m.K. The addition of 10 wt% Al2O3 also reduced the apparent porosity and water absorption to 13.85% and 5.33% respectively for the (SiC-20 wt% kaolin) sample. The apparent porosity and water absorption of the sample (SiC-80 wt% kaolin) with 10 wt% Al2O3 reached the lowest values of 9.44% and 3.55%, respectively. The thermal conductivity decreased from 15 to 12 W/m.K. This study found that adding alumina improves refractory efficiency due to its high melting point, making it ideal for high-temperature applications.
Nanotechnology
Wasan Ziedan; Mukhlis M. Ismail; Wafaa A. Hussain
Abstract
Aqueous solutions with heavy metals such as Cr (VI), Pb, and Cd (II) can have an adverse effect on human health because of their toxicity. As a result, it is important to remove these heavy metals from the aquatic environment to save the human healthy. X-ray diffraction (XRD), Fourier-transform infrared ...
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Aqueous solutions with heavy metals such as Cr (VI), Pb, and Cd (II) can have an adverse effect on human health because of their toxicity. As a result, it is important to remove these heavy metals from the aquatic environment to save the human healthy. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and field-emission scanning electron microscopy (FE-SEM) used in this research to characterize cobalt ferrite (CoFe2O4) nanoparticles and confirm the structure of Co-Fe2O4. These particles were used to make porous samples and burned at 1050 °C in mixtures of (0, 3, 5, 7, and 10) wt.% of cobalt ferrite and kaolin with 20 wt.% of charcoal. These samples serve as adsorbents that remove Pb from the wastewater. The highest rates of removal were confirmed using various treatments at (pH 3, 7, and 9). A Williamson-Hall plot was used to determine the crystal size (33) nm. The FT-IR spectra exhibited spinel-ferrite characteristics. Studies using FE-SEM demonstrated that the sample was in Nano crystalline. Using a vibrating sample magnetometer (VSM), different magnetic properties are taken from the hysteresis loops such as saturation magnetization (Ms) and remanence (Mr) and coercivity (Hc). It was found that increasing ferrite content, increased adsorption efficiency.
Materials Science
Faten Hasan Gata; ENAS MHUI
Abstract
In this paper, Mortar was prepared from medium alumina refractory grog, bricks crashed as a mean material to a particular size, and Iraqi raw (kaolin or bentonite) as binding materials. Refractory bricks were crushed, milled, then sieved to three particle sizes: fine as (1.18 >fine> 0) mm, medium ...
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In this paper, Mortar was prepared from medium alumina refractory grog, bricks crashed as a mean material to a particular size, and Iraqi raw (kaolin or bentonite) as binding materials. Refractory bricks were crushed, milled, then sieved to three particle sizes: fine as (1.18 >fine> 0) mm, medium as (2.36 > medium > 1.18) mm, crushed as (400 > coarse > 2.36) mm. Then these particle sizes were mixed with Iraqi raw kaolin or bentonite with selected ratios (10,15,20,30 and 40) %. Specimens were formed by the wetting method, then drying it at laboratory temperature for one day, followed by firing it at 1200 ℃. Results showed that the porosity of specimens decreases when increasing the clay ratio from 3-4% (kaolin or bentonite), and the bond strength between grog and clay increases when increasing the clay ratio from 2-3% (kaolin or bentonite). Also, the diametrical strength increases when increasing the clay ratio from 4-7% (kaolin or bentonite). The thermal shock results showed that K-mortar is better than B-mortar, depending on the results we obtained through the effect of temperature and diametrical strength. The SEM results showed that mortar structure was produced by adding 40% bentonite with small irregularly shaped. The mortar was produced by adding 40% of kaolin which possesses regular mullite crystals. Finally, the results of the test EDS that K-mortar were revealed in showed that there is no adsorption of carbon while B-mortar showed that there is adsorption of carbon atoms.
