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Factors Governing the Formation of Hierarchically and Sequentially Intergrown MFI Zeolites by Using Simple Diquaternary Ammonium Structure-Directing Agents
Keoh S.H.a, Chaikittisilp W.a, Muraoka K.a, Mukti R.R.b, Shimojima A.c, Kumar P.d, Tsapatsis M.d, Okubo T.a
a Department of Chemical System Engineering, University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
b Division of Inorganic and Physical Chemistry, Research Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Bandung, 40132, Indonesia
c Department of Applied Chemistry, Waseda University, Shinjuku-ku, Tokyo, 169-8555, Japan
d Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, 55455, United States
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]© 2016 American Chemical Society.Zeolites with hierarchical structures are of particular interest because such structures can improve molecular diffusion, particularly that of bulky molecules. N,N,N,N′,N′,N′-Hexapropylpentanediammonium cations (Pr6-diquat-5), a simple diquaternary ammonium organic structure-directing agent (OSDA), can direct the formation of hierarchically and sequentially intergrown MFI zeolites without employing any mesoporogens. In this paper, the effects of OSDAs having structures similar to Pr6-diquat-5 but different lengths of alkyl spacers and/or different substituting groups on the phase selectivity and morphology of the resulting zeolites are presented. It was revealed that the number of carbon atoms between two charged nitrogens in the OSDAs significantly affected the intergrowth and morphology of the crystals formed. In addition, the propyl-substituted OSDAs were found to be very selective to the formation of MFI zeolite, whereas the butyl-substituted OSDAs were not. For Pr6-diquat-5, the condition for the formation of hierarchically and sequentially intergrown MFI zeolites was somewhat narrow with the optimized molar composition of 1 SiO2:0.2 Pr6-diquat-5:0.375-0.500 KOH:200 H2O:4 EtOH. Defect lines observed on the obtained zeolite crystals by a transmission electron microscope were considered to be connectors for such intergrowths. The unique intergrowth formed by Pr6-diquat-5 was surmised to be due to the unusual fitting of Pr6-diquat-5 inside the channels of MFI zeolite, which was explained by comparing molecular dimensions and stabilization energies of each OSDA.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Hierarchical structures,Molar compositions,Molecular diffusion,Molecular dimensions,Number of carbon atoms,Stabilization energy,Structure directing agents,Substituting groups[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text][/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]S.H.K. thanks Panasonic Scholarship and Honjo International Scholarship Foundation for financial support during his graduate study. This work was supported in part by Grant-in- Aids for Scientific Research (A) (JSPS KAKENHI Grant Number: 26249118) and for Young Scientists (B) (JSPS KAKENHI Grant Number: 16K18284) by the Japan Society for the Promotion of Science (JSPS). Parts of this work were conducted at the Center for Nano Lithography andAnalysis at The University of Tokyo, which is supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and at the University of Minnesota Characterization Facility, which receives partial support from the NSF through the NNIN program.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1021/acs.chemmater.6b03887[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]