Microwave Fixed-Bed Reactor for Gas-Phase Glycerol Dehydration: Experimental and Simulation Studies

Conventional fixed-bed reactors have the issue of uneven temperature distribution within the catalyst bed, which influences product selectivity and catalyst stability. Microwave irradiation can realize uniform and bulk heating due to its unique penetration capability. Here, a microwave fixed-bed reactor was developed and applied in a gas-phase glycerol dehydration reaction. Nine microwave-absorbing binary metal oxide catalysts were used to verify the versatility of microwave reactors in gas-solid reactions. Compared with an electric-heating reactor, much better catalyst stability was obtained in a microwave reactor for all of the catalysts. Moreover, no obvious change in catalyst stability was observed with increasing reactor size. Numerical simulation was adopted to explore the intensification mechanism of microwave heating. The largest temperature difference in the microwave reactor was around 10 degrees C, much smaller than that in the electric-heating reactor which reached 57 degrees C. The electric field distribution within the penetration depth of microwave irradiation was homogeneous, resulting in uniform temperature distribution in the microwave reactor and hence good catalyst stability.