We report the synthesis of hierarchical mordenite zeolite nanorods in one step using inexpensive mono‐quaternary ammonium N‐cetyl‐N‐methylpyrrolidinium (C16NMP) as mesoporogen to the synthesis gel. The presence of a small amount of C16NMP results in the formation of 0.6–1 μm rods‐like crystals oriented along the c‐axis with a high mesoporous volume (0.12 cm3 g−1) and external surface area (∼90 m2 g−1) compared to bulk mordenite. Acidity characterization shows that the presence of C16NMP during mordenite formation leads to a redistribution of aluminum in the zeolite framework: the amount of Brønsted acid sites in the side‐pockets (8MR channels) is increased at the expense of those in the 12MR main channels. As these latter acid sites are the ones involved in the conversion of alkene intermediates in bifunctional hydroconversion of alkanes, an optimized hierarchical mordenite prepared with C16NMP displays a more ideal hydrocracking selectivity than bulk MOR prepared solely with sodium.
In this work, we
developed a novel strategy to synthesize porous (alumino)silicate
materials using a single structure-directing agent composed of an
imidazole unit with a hydrophobic tail, namely, 1,2-dimethyl-3-hexadecyl-1H-imidazol-3-ium
bromide (C16dMImz). A wide range of products such as ordered
mesoporous silicas, layered silica–alumina, and hierarchically
porous mordenite zeolite were obtained by varying synthesis parameters
such as temperature and aluminum concentration. By changing crystallization
temperature, we could control the degree of silica condensation and
tune the textural and morphological properties of the final materials.
By varying the aluminum concentration in the gel, we can obtain mesoporous
amorphous silica–alumina or crystalline mordenite zeolite with,
respectively, weak and strong Brønsted acid sites. Obtained acidic
silica–alumina materials displayed promising performance in
catalytic reactions of linear paraffin hydroisomerization and Friedel–Crafts
alkylation of benzene with benzyl alcohol.
A methanethiol-to-olefins (MtTO) equivalent of methanol-to-olefins (MTO) chemistry is demonstrated. CH3SH can be converted to ethylene and propylene in a similar manner as CH3OH over SSZ-13 zeolite involving a hydrocarbon...
The front cover artwork for Issue 12/2019 is provided by researchers from the group of Inorganic Materials and Catalysis, Eindhoven University of Technology (The Netherlands). The image shows how a novel surfactant based on methylpiperidine modified by a hydrophobic tail (C16NMP) can downsize the synthesis of mordenite zeolite from massive crystals into more accessible nanorods. See the Full Paper itself at https://doi.org/10.1002/cctc.201900298.
Here we report a versatile method to synthesize hierarchically porous zeolites with FER, CHA and MFI topologies by using inexpensive mono-quaternary ammonium N-cetyl-N-methylpyrrolidinium (C 16 NMP) as a mesoporogen. Extensive characterization revealed that the mesoporous zeolites are crystalline, possess a high mesopore volume and exhibit comparable Brønsted acidity to their bulk counterparts. Due to the improved accessibility of the microporous domains, these hierarchical zeolites display enhanced performance as catalysts in various reactions such as the dehydration-isomerization of 1-butanol to isobutene (FER) and methanol-to-hydrocarbons reaction (CHA and MFI).Catal. Sci. Technol., 2019, 9, 6737-6748 | 6737This journal is
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