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.
Chemistry
Murtadha S. Al-Eissa; Riaydh S. Almukhtar; Bashir Y. Sherhan
Abstract
The excessive use of plastics in the last years is the challenge that has arisen in managing plastic wastes to avoid dangerous effects. Polyvinyl chloride is part of these wastes. It can be utilized to produce fuel-like petroleum fractions depending on pyrolysis, which is the thermal decomposition of ...
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The excessive use of plastics in the last years is the challenge that has arisen in managing plastic wastes to avoid dangerous effects. Polyvinyl chloride is part of these wastes. It can be utilized to produce fuel-like petroleum fractions depending on pyrolysis, which is the thermal decomposition of plastics in the absence of oxygen. This work aims to reduce environmental pollution and reuse plastic waste as an alternative fuel source. A comparison of the thermal and catalytic processes under the optimum temperature 450 oC, pressure 20 bar, and residence time 1hour in a semi-batch reactor with and without adding Pt/Al2O3 and NiMo/Al2O3 catalysts. Thermo-gravimetric analysis (TGA) analysis was made for PVC. Catalysts were characterized by X-RAY diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The liquid and gas products were analyzed by (GC/MS) to evaluate the quality of products. In the hydro-cracking reaction, most gas products were produced using NiMo/Al2O3 catalyst, about 62.29 wt%. The aromatic and saturated-aliphatic in the liquid using NiMo/Al2O3 catalysts were 21.07 and 72.81 wt%. The aromatics and saturated aliphatic in the liquid product using thermal non-catalytic and Pt/Al2O3 catalysts were 23.83 wt% & 63.52 wt% and 21.88 wt% & 64.01, respectively. The ratio of gasoline range components is the highest in the hydrocracking process on NiMo/Al2O3 catalysts. Using catalytic-hydrocracking on Pt/Al2O3 gives the highest diesel range component. It was confirmed that the generated undesirable product seems was very few in the hydrocracking reactions compared to the thermal cracking reactions.
