Catalytic reforming, alkylation and polymerization processes aim at increasing the yield of high-octane-number gasoline in the refineries. Catalytic reforming uses naphthene-rich, straight-run heavy naphtha as feedstock and produces a high-octane number reformate for the gasoline blending pool in a refinery. Principal catalytic reactions that take place on noble metals (e.g., Pt) and on acidic catalyst supports (e.g., Al2O3) produce high yields of aromatic hydrocarbons and i-alkanes, respectively, to result in a high-octane number product. A valuable by-product from catalytic reforming is hydrogen gas for which the demand is increasing in the refineries, particularly for finishing processes, such as hydrotreatment. Alkylation and polymerization reactions take shorter chains of C3, C4 alkanes and olefins and combine them to get branched C7, C8 alkanes in alkylate, and polymerate, respectively, to increase the yield of high-octane gasoline. Isomerization processes convert n-butane to i-butane to be used as feed in alkylation processes, or isomerize n-C5 and n-C6 to the corresponding i-alkane to produce, again, high-octane-number gasoline stock.
You should now be able to:
- locate the catalytic reforming process in the refinery flow diagram, summarize the process objectives and evaluate the chemical reactions that take place in catalytic reforming to realize the process objectives;
- identify the catalysts used for catalytic reforming, evaluate the reaction network and the activity of catalysts, and illustrate the desirable reactions with specific examples;
- outline the principles of thermodynamics, kinetics and transport phenomena to formulate limits on reaction conditions for controlling desirable and undesirable reactions in catalytic reforming;
- assess the commercial catalytic reforming processes and compare catalyst regeneration practice in each process;
- place the alkylation process in the refinery flow diagram particularly in relation to FCC process and describe the purpose of alkylation;
- demonstrate alkylation reaction mechanisms and evaluate the use of concentrated acid catalysis of alkylation;
- demonstrate polymerization reaction mechanisms and compare alkylation and polymerization reactions and catalysis.
Reminder - Complete all of the Lesson 8 tasks (Blog 8 and Quiz 4)!
You have reached the end of Lesson 8! Double-check the to-do list in the table below to make sure you have completed all of the activities listed there before you begin Lesson 9. Please refer to the Course Syllabus for specific time frames and due dates. Specific directions for the assignment below can be found within this lesson.
If you have any questions, please post them to our Help Discussion (not email), located in Canvas. I will check that discussion forum daily to respond. While you are there, feel free to post your own responses if you, too, are able to help out a classmate.
|J. H. Gary, G. E. Handwerk, Mark J. Kaiser, Chapters 10 (Catalytic Reforming and Isomerization)and 11(Alkylation and Polymerization)