Insights into the methanol to olefins (MTO) performance of SAPO-34 under the stripper conditions of fluid catalytic cracking (FCC)

FCC is an important process for light olefins production, but it's a challenge to enhance the ethylene selectivity. In view of the high selectivity of ethylene and propylene ( S EP ) of MTO and the similar process of FCC and MTO, methanol may be co-fed from the stripper units to improve the selectivity of light olefins ( S LO ), especially ethylene, of a conventional FCC process. Herein, the MTO performance of SAPO-34 under the stripper conditions was studied, and the influences of the coke from heavy oil cracking were analyzed. When MTO was performed following the conditions (500 °C, 7.5–35 h −1 ) in the FCC stripper, the S EP and S LO achieved 83–86% and 91–96%, respectively, the weight ratio of ethylene to propylene ( m Ee : m Pe ) was about 1.2–1.6, and dimethyl ether was not detected. Although more complicated coke was introduced by heavy oil, the active polymethylbenzenes can help retaining the S EP (82.2%) and S LO (89.3%), and the methanol utilization efficiency and m Ee : m Pe were enhanced from 92.5% to 1.21 to 95.3–95.9% and 1.34, respectively. More importantly, the S EP , S LO and m Ee : m Pe can further be enhanced to 85.6%, 91.6%, and 1.52, respectively when SAPO-34 with less strong acid sites was applied. Consequently, SAPO-34 may be used as an FCC catalysts promoter for the development of a modified FCC process with significantly enhanced S LO . • SAPO-34 exhibited excellent MTO performance following the conditions in the FCC stripper. • Polymethylaromatics was created by heavy oil, methanol efficiency increased by 3.4%, m Ee : m Pe increased from 1.21 to 1.34. • The hydrothermal treatment can enhance the light olefins selectivity in the successive heavy oil cracking and MTO process.