Reaction Kinetic Model of Naphtha–Methanol Catalytic Conversion for Light Olefins over HZSM‑5 Based on Structure-Oriented Lumping

To achieve the efficient conversion
of naphtha to light olefins
at low energy consumption, the naphtha–methanol coupling conversion
catalyzed by HZSM-5 was studied at temperatures of 550–700
°C and weight hourly space velocity (WHSV) of 4.6–11.6
h–1. In comparison to the individual naphtha catalytic
cracking system, an improved total conversion was achieved from 80.8
to 88.7 wt % with the increase of the light olefin yield from 39.3
to 50.5 wt % in the naphtha–methanol combined system at the
WHSV of 4.6 h–1 and 650 °C. The kinetic model
of naphtha–methanol coupling conversion was constructed using
the structure-oriented lumping (SOL) method, which made up for the
deficiencies of traditional lumped models in the study of transformation
routes at the molecular level. A total of 41 kinds of molecules were
chosen to depict the feedstock, and 64 reaction rules were formulated
to establish reaction networks in this model. The proposed SOL kinetic
model illustrated that the maximum propylene yield is 28.5 wt % at
650 °C and WHSV of 4.0 h–1, and the maximum
ethylene yield is 35.2 wt % at 700 °C and WHSV of 4.0 h–1. The model can predict the product distribution of the naphtha–methanol
coupling reaction over HZSM-5 investigated in the fixed-bed reactor
reasonably well, with a deviation of less than 1.0%.

为达成在低能耗条件下将轻石脑油高效转化为轻烯烃的目标，本研究对以HZSM-5为催化剂的轻石脑油-甲醇偶联转化过程进行了研究，反应温度范围为550至700摄氏度，重量小时空速（WHSV）为4.6至11.6小时^-1。与单独的轻石脑油催化裂化系统相比，在WHSV为4.6小时^-1和650摄氏度条件下，轻石脑油-甲醇联合系统中总转化率从80.8%提升至88.7%，轻烯烃产率也从39.3%增加至50.5%。采用结构导向集总法（SOL）构建了轻石脑油-甲醇偶联转化的动力学模型，该模型弥补了传统集总模型在分子层面上研究转化路径时的不足。在此模型中，选取了41种分子来描述原料，并制定了64条反应规则以建立反应网络。所提出的SOL动力学模型表明，在650摄氏度和WHSV为4.0小时^-1时，丙烯的最大产率为28.5%，而在700摄氏度和WHSV为4.0小时^-1时，乙烯的最大产率为35.2%。该模型能够对固定床反应器中经HZSM-5催化的轻石脑油-甲醇偶联反应的产品分布进行合理预测，偏差小于1.0%。