- 99 views
- 242 downloads
Alternative Pathways for Olefin Treatment in Thermally Cracked Naphtha
-
- Author / Creator
- Fong, Shirley
-
During thermal cracking of bitumen, olefins are formed via free radical reactions and are mainly concentrated in the naphtha and distillate cut of the upgraded bitumen. Olefins are undesirable in the upgraded bitumen product because they are associated with equipment fouling. As a result, these compounds are commonly treated via hydrogenation in bitumen upgrader facilities. Hydrogenation is not a preferred technology for use in partial upgrading. Therefore, the purpose of this research is to study alternative pathways to treat the olefins in thermally cracked naphtha without the use of hydrogen.
Two alternatives were evaluated. The first alternative consists of using phosphoric acid to reactively absorb the olefins in the naphtha by forming alkyl phosphoric acid esters. The chemistry between olefins and phosphoric acid was studied by reacting model compounds namely olefins within the range of C5-C7 with phosphoric acid at 50 ℃ at different reaction times. The results indicated that the process for olefin removal using phosphoric acid is inefficient due to slow reaction rate at a temperature where the alkyl phosphoric acid esters would be stable. Furthermore, the alkyl phosphoric acid esters formed from C6 and C7 olefins were soluble in the naphtha. The low absorption rate and solubility of some alkyl phosphoric acids in the organic phase made it impractical to develop a temperature swing absorption process based on phosphoric acid.
The second alternative studied the use of asphaltenes to treat the olefins in the thermally cracked naphtha via hydrogen transfer. The study was divided into three sections: (i) a preliminary study using model compounds as hydrogen donor and acceptor. It was found that hydrogen transfer could be employed for saturation of olefins. (ii) The second section used asphaltenes as hydrogen donor and model olefinic compound as hydrogen acceptor, the feed was reacted at different reaction conditions. It was found that asphaltenes were capable of transferring hydrogens to saturate the olefin. (iii) The third section used asphaltenes as hydrogen donor and thermally cracked naphtha as hydrogen acceptor. Asphaltenes were capable of hydrogenating the olefins in the cracked naphtha. The study indicated that hydrogen transfer could be considered as strategy for olefin treating. The results of the applied study using asphaltenes to treat thermally cracked naphtha were encouraging.
-
- Graduation date
- Fall 2019
-
- Type of Item
- Thesis
-
- Degree
- Master of Science
-
- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.