3.Chemical processing of distillate oil(Secondaryprocessing)CatalyticreformingCatalytic crackingCatalytic hydrocrackingPyrolysis of hydrocarbons
3. Chemical processing of distillate oil （Secondary processing） ⚫ Catalytic reforming ⚫ Catalytic cracking ⚫ Catalytic hydrocracking ⚫ Pyrolysis of hydrocarbons
(1)CatalyticreformingCatalytic reforming is a key process in the production ofgasoline components with a high octane number. It also play animportantrolein the production of aromaticsforthechemicalindustry. Furthermore, catalytic reforming is a major source ofhydrogen.Raw materials of the catalytic reforming are thenaphthaDuring catalytic reforming the change in molecular weight ofthe feedis relatively small, the process mainly involvesrearrangement ofhydrocarbon structures
⚫ Catalytic reforming is a key process in the production of gasoline components with a high octane number. It also play an important role in the production of aromatics for the chemical industry. Furthermore, catalytic reforming is a major source of hydrogen. ⚫ Raw materials of the catalytic reforming are the naphtha ⚫ During catalytic reforming the change in molecular weight of the feed is relatively small, the process mainly involves rearrangement of hydrocarbon structures. (1) Catalytic reforming
0C-0--0IscmerizationC-C-C-C-C-C-0izatiorAromatizationCombinationReactions occurring during catalytic reforming
Reactions occurring during catalytic reforming
(2)CatalyticcrackingThe main purpose of the catalytic cracking is to increasegasoline outputand quality.Raw materials of the catalytic cracking are diesel, lubricatingoil,etc.Cracking is catalyzed by solid acids,whichpromotethecleavage of C-C bonds.Thekey intermediatesare carbocationsThey are formed by the action of the acid sites of the catalyst.Besides C-C bond cleavage a large number of other reactionsoccur:isomerization;protonation,deprotonation;alkylation;polymerization; cyclization,condensation.Catalytic cracking comprises a complex network of reactions,bothintra-molecularandinter-molecular
(2) Catalytic cracking ⚫ The main purpose of the catalytic cracking is to increase gasoline output and quality. ⚫ Raw materials of the catalytic cracking are diesel, lubricating oil, etc. ⚫ Cracking is catalyzed by solid acids, which promote the cleavage of C-C bonds. The key intermediates are carbocations. They are formed by the action of the acid sites of the catalyst. ⚫ Besides C-C bond cleavage a large number of other reactions occur: isomerization; protonation, deprotonation; alkylation; polymerization; cyclization, condensation. ⚫ Catalytic cracking comprises a complex network of reactions, both intra-molecular and inter-molecular
H,C-CH,-CH2-CH2-CH2-CH2-CHn-AlkaneInitationHC-CH-CH2-CH2-CH2-CH2-CH3Classicalcarbeniumion小H,C-CH-CH-CH2-CH2-CHProtonatedcyclopropaneHCH2★hydide shits +IsomenzationC-Cbond breaking★HC-CH-CH3 + H,C-CH-CH3H,C--CH-CH-CH,-CH2-CH3CHCH3n-Alkeneetc.hydnide transfer1H,C-CH-CH3CH3iso-AlkaneScheme 3.1Mechanism for catalytic cracking of alkanes, including isonenization