Crystallization process of zeolite rho prepared by hydrothermal synthesis using 18-crown-6 ether as organic template

► A zeolite rho prepared by hydrothermal synthesis using 18-crown-6 ether has four synthesis steps. ► The dehydration and condensation reaction occurred in the 0-2 h period. ► The particle size of the amorphous aluminosilicate increased in the 3-20 h period. ► The crystallization and crystal growth occurred with incorporation 18C6 in the 20-48 h period. ► The zeolite rho gently grew with an increase in Na/Si ratio in the 48-96 h period.