(3)Condensationreactions ofaromaticsRRR.HAromatics is stability,C.H+C.Handitis noteasy forring-openCHreaction,anditis easyfor+C,Hside-chain scission or aromaticcondensation reaction.Coking
(3) Condensation reactions of aromatics + + R1 R3 R4H R2 Aromatics is stability, and it is not easy for ring-open reaction, and it is easy for side-chain scission or aromatic condensation reaction. 结焦 CH3 + C3H6 + C2H4 C3H7 结焦 CH3 + C3H6 + C2H4 C3H7 Coking
5.Coking and forming carbon reactions in the cracking process(1)Theformationofcarbonfromalkenes bythealkynesintermediatestageat900-1000℃CCH2--CH,-----→ CH2--CH CHCHCHH(2)Theformationof cokebytheintermediate stage ofaromatics500-900℃焦紫二联蔡三联蔡+可=可一可=可可可结焦
5. Coking and forming carbon reactions in the cracking process (1) The formation of carbon from alkenes by the alkynes intermediate stage at 900-1000℃ (2) The formation of coke by the intermediate stage of aromatics 500-900℃ -H -H 结焦 · -H -H 结焦 ·
The reactions of the forming carbon (900-1000C)andcoking (500-900C) are typical consecutive reactions.Monocyclicring orPolycyclic aromaticsCondensedaromaticsfewrings aromaticsAsphalteneCokeLiquid tar oil
Monocyclic ring or few rings aromatics Polycyclic aromatics Condensed aromatics Liquid tar oil Asphaltene Coke The reactions of the forming carbon (900-1000℃ ) and coking (500-900℃) are typical consecutive reactions
Differenceof cokeandcarbonDifference formation process :The formation of carbon from alkenes by thealkynes intermediate stage, and the formation ofcoke by the aromatic intermediate stage.Difference hydrogen content:The hydrogen is not almost contained in carbon,but the trace amounts of hydrogen (0.1-0.3%) iscontained incoke
Difference formation process : The formation of carbon from alkenes by the alkynes intermediate stage, and the formation of coke by the aromatic intermediate stage. Difference hydrogen content : The hydrogen is not almost contained in carbon, but the trace amounts of hydrogen (0.1-0.3％) is contained in coke. Difference of coke and carbon
6.The cracking reaction rules of various serieshydrocarbonsIt is the most favorable to form ethene and propenefrom normal alkanes cracking among various serieshydrocarbons.Pyrolysis of macromolecule alkenes to form ethene andpropene.The reactions forming aromatics are superior to thereactions forming mono olefine from cycloalkanes
✓ It is the most favorable to form ethene and propene from normal alkanes cracking among various series hydrocarbons. ✓ Pyrolysis of macromolecule alkenes to form ethene and propene. ✓ The reactions forming aromatics are superior to the reactions forming mono olefine from cycloalkanes. 6. The cracking reaction rules of various series hydrocarbons