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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
Author name:
طارق محمد نايف
Supervisor name:
Abdul | Halim A.K. Mohammed | Hussein K. Hussein
General topic:
Chemical Engineering
Specific topic:
Chemical Engineering
Degree:
Doctorate
University:
University of Baghdad - College Of Engineering - Department Of Chemical Engineering
Language:
English
University location:
Baghdad
First pages:
38T275 - p.pdf
Abstract:
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.
