Reaction behaviors and feed characterization of light hydrocarbon catalytic pyrolysis for production of light olefins

doi:10.11949/j.issn.0438-1157.20160398

Abstract

Abstract:

The cracking performance of light hydrocarbon model compounds such as n-paraffins, i-paraffins, naphthalenes, aromatics and n-olefins on a mesoporous catalyst based on ZSM-5 molecular sieve was investigated in a small scale fixed bed reactor. The experimental results showed that the cracking performance in the order from good to poor was:n-olefins, n-paraffins, naphthalenes, i-paraffins, and aromatics. For n-paraffins, i-paraffins and naphthalenes, the yields of total light olefins were largely different whereas the selectivities of total light olefins were all around 56.57%. The main liquid components were pentene, benzene, toluene and xylene besides unreacted feed. In case of straight-run naphtha, the yield of ethylene plus propylene and the yield of total light olefins increased with the increase in reaction temperature and the decrease in weight hourly space velocity. At a condition of reaction temperature of 680℃, a weight hourly space velocity of 4.32 h^-1 and a steam-to-oil weight ratio of 0.35, naphtha catalytic pyrolysis yielded 41.94% (mass) of total light olefins and 35.87% (mass) of ethylene plus propylene, which the ratio of propylene to ethylene at above 1.2 was much higher than that of naphtha steam cracking. A large amount of olefins and paraffins in the liquid sample of naphtha catalytic pyrolysis indicated that the liquid sample still had good cracking performance. A new characterization parameter (KF), a function of H/C atomic ratio, relative density and molecular weight of feeds, was proposed to be more suitable than KCP for characterizing catalytic pyrolysis of light hydrocarbons.

Key words: chemical reaction, catalysis, fixed-bed, light hydrocarbon, pyrolysis, ethylene, propylene

摘要：

利用小型固定床实验装置对比研究了轻烃模型化合物的催化裂解性能，从优到劣的顺序依次是正构烯烃、正构烷烃、环烷烃、异构烷烃、芳香烃。正构烷烃、异构烷烃与环烷烃催化裂解的总低碳烯烃收率有较大差别，但是总低碳烯烃选择性却均在56.57%左右。研究了直馏石脑油的催化裂解性能，发现乙丙烯收率和总低碳烯烃收率随反应温度的升高及重时空速的降低而逐渐增大；在反应温度680℃、重时空速4.32 h^-1和水油稀释比0.35的条件下，乙丙烯收率35.87%（质量），总低碳烯烃收率为41.94%（质量）。针对轻烃催化裂解提出了原料特征化参数KF，它是原料H/C原子比、相对密度与分子量的函数，能较好地表征轻烃原料的催化裂解性能。

关键词: 化学反应, 催化, 固定床, 轻烃, 裂解, 乙烯, 丙烯

CLC Number:

TE624.4

ZHANG Rui, LIU Guili, WANG Yadong, LIU Haiyan, LIU Zhichang, MENG Xianghai. Reaction behaviors and feed characterization of light hydrocarbon catalytic pyrolysis for production of light olefins[J]. CIESC Journal, 2016, 67(8): 3387-3393.

张睿, 刘贵丽, 王亚东, 刘海燕, 刘植昌, 孟祥海. 轻烃催化裂解制低碳烯烃反应规律与原料特征化[J]. 化工学报, 2016, 67(8): 3387-3393.

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