A kinetic model for methanol-to-propylene process in the presence of co- feeding of C4-C5 olefin mixture over H-ZSM-5 catalyst

The side reactions play an evident role in the selectivity of propylene in methanol to propylene (MTP) process. Recycling by-products such as C-4 and C-5 hydrocarbon cuts is an effective way to utilize these hydrocarbons and to improve the propylene selectivity. So, the aim of this study was to present a kinetic model for the MTP process over the H-ZSM-5 (Si/Al = 200) catalyst in the presence of co-reaction of methanol and C-4-C-5 olefin mixture based on the Langmuir-Hinshelwood theory. This model was established on a comprehensive mechanism including methanol conversion, methylation, cracking, hydrogenation, dehydrogenation, and oligomerization reactions. The Response Surface Methodology based on Central Composite Design was applied to evaluate the impact of C-4(-) (5-16 wt%) and C-5(-) (2-9 wt%) mass fraction, WHSV (1.93-7.73 h(-1)), and temperature (455-485 degrees C) on the product distribution. It was found that the co-feeding of C-4-C-5 olefin mixture with methanol can enhance the propylene selectivity up to 73% by controlling the operating conditions. The excellent agreement between the model prediction and experimental data shows that the proposed kinetic model accurately describes the product distribution, and is applicable to this process.

Automated summary

Secondary reactions significantly impact the propylene selectivity in the methanol to propylene (MTP) process. A kinetic model based on the Langmuir-Hinshelwood theory was developed to study the co-reaction of methanol and C-4-C-5 olefin mixture. By controlling the operating conditions, the propylene selectivity can be enhanced up to 73%.