Organic-free synthesis of MOR nanoassemblies with excellent DME carbonylation performance

Seed-assisted low alkalinity gel system was developed to explore the organic-free synthesis of MOR zeolite. MOR nanoassemblies with Si/Al ratio (SAR) up to 9.4 and high solid yield (84–94%) were successfully obtained under controlled low alkalinity conditions. Characterization results demonstrate th...

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Veröffentlicht in:Chinese journal of catalysis 2021-09, Vol.42 (9), p.1468-1477
Hauptverfasser: Cao, Kaipeng, Fan, Dong, Zeng, Shu, Fan, Benhan, Chen, Nan, Gao, Mingbin, Zhu, Dali, Wang, Linying, Tian, Peng, Liu, Zhongmin
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Sprache:eng
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Zusammenfassung:Seed-assisted low alkalinity gel system was developed to explore the organic-free synthesis of MOR zeolite. MOR nanoassemblies with Si/Al ratio (SAR) up to 9.4 and high solid yield (84–94%) were successfully obtained under controlled low alkalinity conditions. Characterization results demonstrate that the acid strength increases in parallel with the SAR, while the total acid amount and the proton distribution in the main channels and the side pockets are similar for the samples. The proton distribution in the H-MOR is not straightforwardly related to the Na+ distribution in the as-synthesized MOR, implying the transfer of the protons among the oxygen sites of framework T atom. Relative to low-silica samples I-5.3 and I-7.4, sample I-9.4 displays the best mass transfer performance and accessibility of the acid sites by pyridine due to its relatively low Al density and mild dealumination degree. Correspondingly, sample I-9.4 (pyridine-modified catalyst) shows the best activity with ca. 100% selectivity of methyl acetate (MAc) in the DME carbonylation reaction. The high steady MAc yield (6.8 mmol/g/h) over sample I-9.4 suggests the promising application of MOR nanoassemblies synthesized by this economical organic-free strategy MOR nanoassemblies with SAR up to 9.4 were synthesized efficiently via an organic-free route. A steady MAc yield of 6.8 mmol/g/h with ca. 100% selectivity was achieved on pyridine-modified H-MOR nanoassemblies with SAR of 9.4, owing to superior mass transfer performance and accessibility of the acid sites.
ISSN:1872-2067
0253-9837
1872-2067
DOI:10.1016/S1872-2067(20)63777-9