Thermodynamics analysis and reaction performance for catalytic cracking of C_4 olefins to propylene and ethylene
Liu Juntao;Sun Fengxia;Teng Jiawei;Sinopec Shanghai Research Institute of Petrochemical Technology;
Using C2- C4 olefins as reaction model of production of propylene and ethylene from catalytic cracking of C4 olefins,the thermodynamics performance for C4 olefins cracking was calculated based on the principle of minimum gibbs free energy. The results showed that equilibrium yield of ethylene increased with the increase of temperature,and equilibrium yield of propylene reached 44. 8% at 610 ℃.On the other hand,equilibrium yield of ethylene enhanced with the decrease of pressure at 580 ℃,especially while pressure was below 0. 1 MPa,the equilibrium yield of ethylene had a rapid increase from21. 8% at 0. 1 MPa to 46. 5% at 0. 01 MPa; equilibrium yield of propylene increased slightly with the decrease of pressure at the range of( 0. 05- 0. 8) MPa,and reached 45% at 0. 05 MPa and subsequently decreased rapidly. The comparison of thermodynamics equilibrium data and experiment test results showed that the yield of ethylene and propylene and butene conversion from thermodynamics calculation data were in accord with experiment results based on production of propylene and ethylene from butane catalytic cracking over ZSM-5 molecular sieve catalyst. In order to obtain optimum propylene yield,the appropriate reaction condition suggested at reaction temperature range of( 500- 580) ℃ and pressure 0. 05 MPa.