Dancing and recrystallizing of Na2CO3 particles during catalytic gasification: Instructing the industrial catalysts loading procedures

Abstract

The migrating of alkali at high temperature is closely related to catalytic gasification, activated carbon preparation and volatilization of alkali. In this work, a simple but effective and visible method was used to reveal the newfound migrating modes between Na2CO3 particles and coal char by situ heating stage microscope. Moreover, the effects of Na2CO3 migration on the gasification and the catalyst-loaded procedure were also evaluated. The video results recorded by microscope visually shows that Brownian motion and recrystallization of Na2CO3 particles contribute to the migration between Na2CO3 and coal during catalytic gasification. Brownian motion acts on the small Na2CO3 particles (<20 μm) and recrystallization acts on the big particles. The results show that Na2CO3 particles (<20 μm) actively moves at temperatures range of 660–730 °C, and when the moving Na2CO3 closes to the coal char particles, the coal char draws the jumping Na2CO3 particles, and the moving Na2CO3 particles adheres to the coal char surface. For the big Na2CO3 particles, lots of tiny particles can migrate to coal char by recrystallization in the surrounding of Na2CO3 particles, and the coal char has priority to attract the recrystallization of the tiny particle on the coal char surface. The Brownian motion and recrystallization complete Na2CO3 migration from Na2CO3 to coal, and Na2CO3 loaded by mechanical mixing can complete even Na dispersion as impregnation method does.