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%.