Methanol-to-olefins (MTO) is industrially applied to produce ethylene and propylene using methanol converted from coal

synthetic gas

and biomass. SAPO-34 zeolites

as the most efficient catalyst in MTO process

are subject to the rapid deactivation due to coke deposition. Recent work shows that steam regeneration can provide advantages such as low carbon dioxide emission and enhanced light olefins yield in MTO process

compared to that by air regeneration. A kinetic study on the steam regeneration of spent SAPO-34 catalyst has been carried out in this work. In doing so

we first investigated the effect of temperature on the regeneration performance by monitoring the crystal structure

acidity

residual coke properties and other structural parameters. The results show that with the increase of regeneration temperature

the compositions of residual coke on the catalyst change from pyrene and phenanthrene to naphthalene

which are normally considered as active hydrocarbon pool species in MTO reaction. However

when the regeneration temperature is too high

nitrogen oxides can be found in the residual coke. Meanwhile

as the regeneration temperature increases

the quantity of

residual coke reduces and the acidity

BET surface area and pore structure of the regenerated samples can be better recovered

resulting in prolonging catalyst lifetime. We have further derived the kinetics of steam regeneration

and obtained an activation energy of about 177.8 kJ·mol

-1

. Compared that with air regeneration

the activation energy of steam regeneration is higher

indicating that the steam regeneration process is more difficult to occur.