Synthesis of silicate and alumina pillared MWW zeolite as ethane dehydroaromatization catalyst

Pillared MWW zeolites were prepared with polymeric hydroxyl-aluminum Keggin-Al13 cations and tetraethylorthosilicate as pillaring agents to investigate catalyst acidity and interlayer structure impact on ethane dehydroaromatization. The intercalation effect of the pillars causes the MWW zeolite to be stretched between the layers, which cause the 12 member ring (MR) pocket structure to be exposed to outside surface. The modification method can effectively generate the micropore and mesopore MWW zeolite composite, MCM-36. The introduction of silica columns and alumina columns led to the overall decrease of acidity and the increase of weak and Lewis acid of pillared MWW zeolites, respectively. Although the strong Bro center dot nsted acid sites of MWW play major effect on catalyzing aromatization of ethylene generated by the dehydrogenation of ethane to aromatics, the modification decreases the cracking of ethylene oligomers. The 12-MR pockets exposed on the pillared MWW zeolite can provide more reaction sites for xylene generation.

Automated summary

The use of polymeric hydroxyl-aluminum Keggin-Al13 cations and tetraethylorthosilicate as pillaring agents altered the interlayer structure of MWW zeolites, affecting their acidity and resulting in the formation of the composite MCM-36. Introduction of silica and alumina pillars led to changes in acidity, reducing overall acidity and increasing weak and Lewis acid sites in pillared MWW zeolites.