关键词: MTO, 积炭, 反应动力学, 流化床, 多级串联, 模拟

Abstract:

Methanol to olefins (MTO) is a new technology of modern coal-to-chemicals industry. The catalyst performance and selectivity of light olefin in the MTO process can be remarkably improved by well-designed reactor operating mode. The simulation of MTO reaction in a single, two and three fluidized-bed connected in series was carried out by using the reaction and deactivation kinetics experimentally obtained on the commercial SAPO-34 catalyst, combined with fluidized-bed dynamic two-phase model and particle residence time model. The effects of catalyst residence time, gas-solid cocurrent and countercurrent flow on the MTO performance were investigated. The simulation results show that the catalyst coke content and selectivity of the light olefin depend on the catalyst residence time. The multi-bed in series operating mode will reduce the particle back-mixing, which results in a more uniform coke distribution and a longer catalyst lifetime. For the gas-solid countercurrent flow of two reactors in series, the second reactor is used to pre-coke the catalysts before entering into the first reactor and therefore the light olefin selectivity and the total coke content are increased. The catalyst production capacity of one pass is increased by 24.4% compared with that of single reactor mode. Three reactors connected in series mode can fully utilize the different functions of each reactor for pre-coking, MTO reaction and post-coking, bring about a 1% increase in the selectivity of the light olefin and a 31.1% increase in the catalyst production capacity when compared with the single reactor.

Key words: MTO, coke, reaction kinetics, fluidized-bed, multi-bed in series, simulation