Aromatization of butylenes over nano-sized ZSM-5 zeolite
The aromatization of the butylenes in C4 liquefied petroleum gas (LPG) over a nano-sized ZSM-5 zeolite catalyst,denoted DLG-1,was studied at a mild temperature.Emphasis was given to the influence of feed impurities and reaction conditions,such as reaction temperature,pressure,weight hourly space velocity of LPG (WHSVLPG) on the activity and stability of the aromatization catalyst.The results showed that,both diene and alkaline nitrogen-containing compounds had negative influence on the aromatization stability of the catalyst.Comparatively,the negative influence of the alkaline nitrogen-containing compounds (mainly in the manner of strong chemisorption on the acid sites) was much stronger than that of diene.On the other hand,reaction temperature,pressure and WHSVLPG also showed significant influence on the performance of the catalyst.The optimum reaction conditions were 450℃,2.0 MPa and WHSVLPG 0.83 h-1.A high coking rate of the catalyst was observed when higher temperature,higher pressure and higher WHSVLPG were used.