Study on Catalytic Upgrading of Gaseous Tar by Synergistic Effect of La-Acid on Y Zeolite

In recent years, metal-loaded zeolites have been widely adopted and applied to catalytic pyrolysis technology. In this article, two series of LaNaY-x% and LaHY-x% catalysts were prepared, and their synergistic effects on La and acid sites in the catalytic upgrading of coal pyrolysis gaseous tar were studied. It was found that the LaNaY-4% catalyst could significantly reduce the tar yield to 4.09%, and the gas yield reached its highest value of 18.70%. The La mainly occupied the position in the sodalite cage. Compared with LaNaY-x%, the LaHY-x% catalyst slightly increased the yield of tar and gas but decreased the yield of water. The metal can activate the hydrogen-rich components to form small molecular free radicals, which can stabilize the cracking fragments, promote the formation of small molecular light tar and gas, and block the formation of wastewater. In terms of tar components, the LaHY-8% catalyst showed the highest proportion (95.03%) and yield of light tar (4.47%). Since LaHY-8% is rich in La, it occupies a large proportion in the supercage and there are different cascades of acids, resulting in a good synergistic effect. But the coke of the LaHY-x% catalyst is increased compared with that of the LaNaY-x% catalyst. The formation of coke can be reduced with an increase in La loading. The activation effect of La on hydrogen-rich components can avoid the formation of coke.