The Influence of Different Base Sources on MCM-22 Zeolite Synthesis

This article analyzes the thermodynamics of alumina dissolution in alkaline solution.Researchers synthesized zeolites using NaOH,KOH and Ba(OH)2 as alkali sources respectively with n(SiO2)/n(Al2O3)=60,n(H2O)/n(SiO2)=24.5 and n(HMI)/n(SiO2)=0.1.When NaOH was used as the alkali source and n(Na+)/n(Al2O3)0.049,the synthetic product was amorphous,and the product was MCM-22 zeolite when 0.049≤n(Na+)/n(Al2O3)≤0.123.The product obtained was ZSM-35 zeolite,however,when n(Na+)/n(Al2O3)=0.245.When KOH was used as the alkali source and within the range of research,i.e.n(K+)/n(SiO2)=0.0031-0.0873,the products were all amorphous.When Ba(OH)2 was used as the alkali source and n(Ba2+)/n(SiO2)≤0.0031,the product was amorphous.When 0.0062≤n(Ba2+)/n(SiO2)≤0.0488,all the products synthesized were Ba-ZSM-35 zeolites,and the crystallinity of Ba-ZSM-35 decreases with the increase of the value of n(Ba2+)/n(SiO2).The results showed that Na+ is essential to the synthesis of MCM-22 zeolite under certain conditions.