Background: Propylene is one of the main petrochemical building blocks applied as a
feedstock for various chemical and polymer intermediates. The methanol-to-propylene (MTP)
processes are reliable options for propylene production from non-petroleum resources. The highsilica
ZSM-5 zeolite is found to be a reliable candidate for the methanol to propylene catalysis.
Objective: In this study, the mesoporosity was first introduced into a high silica ZSM-5 zeolite via
an alkaline treatment by NaOH solution with piperidine to decrease the diffusion limitation, and
then the structure of zeolite was stabilized by phosphorus modification to improve the acidic
properties and to enhance the catalyst stability.
Methods: High-silica H-ZSM-5 catalysts (Si/Al = 200) were successfully prepared through
microwave-assisted hydrothermal technique in the presence of tetrapropyl ammonium hydroxide
(TPAOH) structure-directing agent. The mesoporosity was efficiently introduced into the ZSM-5
crystals via desilication derived from alkaline NaOH/piperidine solution. Then, the acidity of the
desilicated ZSM-5 samples was improved using phosphorus modification. The catalysts were
subjected to XRD, ICP-OES, FE-SEM, BET, TGA, FT-IR and NH3-TPD analysis.
Results: The catalytic performance of the prepared catalysts in the methanol to propylene (MTP)
reaction was examined in a fixed-bed reactor at 475 °C, atmospheric pressure and methanol WHSV
of 0.9 h-1. The results showed that the alkaline treatment in NaOH/piperidine solution created uniform
mesoporosity with no severe damage in the crystal structure. Similarly, phosphorus modification
developed the acidic features and led to the optimal catalytic efficiency in terms of the maximum
propylene selectivity (49.16%) and P/E ratio (5.97) as well as the catalyst lifetime.
Conclusion: The results showed an excellent catalytic activity in terms of 99.21% methanol
conversion, good propylene selectivity up to 49.16%, a high ratio of P/E of 5.97 and a low
selectivity to C5 + hydrocarbons of 11.57% for ZS-D-PI-P sample.