Fig. 1 . Schematic diagram of a circulating fluidized bed scaled-up reactor.
3. Results anddiscussion
3.1 Laboratory scale-up experiment
We used the Fe-Mo/ZSM-5 dual-function catalyst in the circulating fluidized bed scaled-up reactor to verify the reaction effect after 3 filling cycles and continuous feeding under the same reaction conditions(reaction temperature = 390 °C, methanol/air ratio = 0.5, reaction space velocity = 15000 h-1). The performance of the Fe-Mo/ZSM-5 catalyst in the micro-reactor and the circulating fluidized bed scaled-up reactor were compared in Table1. It can be seen from Table 1 that the methanol conversion rate of the three scaled-up reactors is better than that of the micro fluidized bed reactor. We believe this was because the regenerated catalyst brings more catalytic active centers and accelerates the methanol reaction rate. At the same time, the selectivity decreased for DMM and increased for FA. This was because the regenerated catalyst brings too many oxidation active centers to promote the adsorption of more methanol to form methoxy groups, but it is not desorbed in time for the next polycondensation reaction. Compared with the micro-fluidized bed reactor, the pilot-scale test results showed a better conversion rate, indicating that the pilot scale-up experiment of the process was successful. The yield of DMM was as high as 79.6%, which is the best reported in the literature so far(as shown in Table S1). These results indicate that the successful completion of the laboratory micro-reaction to the pilot scale-up process experiment has laid a foundation for the in-depth development, popularization and application of new process technologies.
Table. 1. Catalytic activity of Fe-Mo/ZSM-5 catalyst in micro fluidized bed and Circulating fluidized bed scaled-up reactor.