Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha  

作　　者：Dongyang Liu Yibo Zhi Yuen Bai Liang Zhao Jinsen Gao Chunming Xu 

机构地区：[1]State Key Laboratory of Heavy Oil Processing,China University of Petroleum(Beijing),Beijing 102249,China

出　　处：《Frontiers of Chemical Science and Engineering》2022年第12期1700-1712,共13页化学科学与工程前沿（英文版）

基　　金：The authors acknowledge the support from the National Natural Science Foundation of China(Grant No.22021004);the National Key Research and Development Program of China(Grant No.2020YFA0210900)。

摘　　要：The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha.Herein,for a better catalyst design and operation parameters optimization,the reaction pathways and equilibrium yields for the catalytic pyrolysis of C_(5-8)n/iso/cyclo-paraffins were analyzed thermodynamically.The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways,respectively.However,the formation of light paraffin severely limits the maximum selectivity toward light olefins.The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins.The results are thus useful as a direction for future catalyst improvements,facilitating superior reaction pathways to enhance light olefins.In addition,the equilibrium yield of light olefins increased with increasing the chain length,and the introduction of cyclo-paraffin inhibits the formation of light olefins.High temperatures and low pressures favor the formation of ethylene,and moderate temperatures and low pressures favor the formation of propylene.n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90%and 55.77%,respectively.This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C_(5-8)n/iso/cyclo-paraffins from a thermodynamic point of view.

关 键 词：NAPHTHA catalytic pyrolysis reaction pathway equilibrium yield 

分 类 号：O64[理学—物理化学]