TY - JOUR
T1 - ZSM-12 nanocrystals with tunable acidity directed by rigid diquats
T2 - Synthesis and catalytic applications
AU - Li, Shaojie
AU - Mezari, Brahim
AU - Wu, Hanglong
AU - Kosinov, Nikolay
AU - Hensen, Emiel J.M.
N1 - Funding Information:
Shaojie Li acknowledges financial support from the China Scholarship Council. The authors thank A. M. Elemans-Mehring for ICP measurements, R. C. J. van de Poll and A. Radu for TEM measurements.
PY - 2023/2/1
Y1 - 2023/2/1
N2 - ZSM-12 is an important zeolite used as a catalyst in several industrial hydrocarbon conversion reactions. Facile synthesis of nanocrystalline ZSM-12 in a wide Si/Al compositional range remains a challenge. Here we report the successful synthesis of nanosized ZSM-12 from flexible aluminosilicate initial gels (Si/Al = 20, 50 and 100) using rigid diquaternary ammonium compounds (p-xylene-bridged bis-methylpyrrolidinium, -methylpiperidinium and −1,2-dimethylimidazolium -) as the organic structure-directing agents (OSDAs). The effective structure-directing ability of these OSDAs for nanocrystalline ZSM-12 synthesis is due to the strong interaction between the OSDA and the growing zeolite framework. The resulting nanocrystalline ZSM-12 zeolites with proper acidity exhibit substantially improved catalytic performance in hydroconversion of n-hexadecane (n-C16) and methanol-to-hydrocarbons reactions. TGA analysis of used catalysts and in situ IR spectroscopy of intra-zeolite organic species during the MTH reaction revealed that the smaller crystals result in lighter aromatics and less coke deposition due to the higher rate of desorption attributed to the larger external surface area.
AB - ZSM-12 is an important zeolite used as a catalyst in several industrial hydrocarbon conversion reactions. Facile synthesis of nanocrystalline ZSM-12 in a wide Si/Al compositional range remains a challenge. Here we report the successful synthesis of nanosized ZSM-12 from flexible aluminosilicate initial gels (Si/Al = 20, 50 and 100) using rigid diquaternary ammonium compounds (p-xylene-bridged bis-methylpyrrolidinium, -methylpiperidinium and −1,2-dimethylimidazolium -) as the organic structure-directing agents (OSDAs). The effective structure-directing ability of these OSDAs for nanocrystalline ZSM-12 synthesis is due to the strong interaction between the OSDA and the growing zeolite framework. The resulting nanocrystalline ZSM-12 zeolites with proper acidity exhibit substantially improved catalytic performance in hydroconversion of n-hexadecane (n-C16) and methanol-to-hydrocarbons reactions. TGA analysis of used catalysts and in situ IR spectroscopy of intra-zeolite organic species during the MTH reaction revealed that the smaller crystals result in lighter aromatics and less coke deposition due to the higher rate of desorption attributed to the larger external surface area.
KW - Methanol-to-hydrocarbons
KW - N-paraffins hydroconversion
KW - nanosized ZSM-12
KW - Structure-directing agent
KW - Zeolite
UR - http://www.scopus.com/inward/record.url?scp=85140772875&partnerID=8YFLogxK
U2 - 10.1016/j.fuel.2022.126363
DO - 10.1016/j.fuel.2022.126363
M3 - Article
AN - SCOPUS:85140772875
SN - 0016-2361
VL - 333
JO - Fuel
JF - Fuel
M1 - 126363
ER -