MWW-type catalysts for gas phase glycerol dehydration to acrolein

Carriço, Camila Santana; Cruz, Fernanda Tátia; Santos, Maurício B. dos; Oliveira, Daiana de; Pastore, Heloise O.; Andrade, Heloysa Martins Carvalho; Mascarenhas, Artur J.S.

doi:10.1016/j.jcat.2015.11.010

Cited by 52 publications

(31 citation statements)

References 38 publications

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“…In comparison to the MCM-22 parent material, MCM-36 and ITQ-2 have more strong Lewis acid sites, consistent with a partial dealumination during the swelling or pillaring processes[26,28,219,265]. Opposite to this trend, the MCM-36 or ITQ-2 prepared under mild conditions show lower acid site strength than MCM-22[259,261,266].…”

mentioning

confidence: 71%

“…The absolute quantity of both Brønsed and Lewis acid sites in MCM-22, ITQ-2, and MCM-36 has varied across different research groups [182]. Overall, the data have shown that the pillarization and exfoliation processes result in a decrease in the Brønsted acid sites, while the Lewis acid sites are either not affected or increased slightly [182,266]. Except for the very early work [187,258] that showed that pillared MCM-36 and exfoliated ITQ-2 had higher percentages of strong acid sites than that of 3D MCM-22 zeolite, most studies have drawn the opposite conclusion, in which the 2D MCM-36 or ITQ-2 has lower fractions of strong acid sites ( Table 12).…”

Section: Acidity Characterization For 2d Mww Zeolitesmentioning

confidence: 98%

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Two-Dimensional Zeolite Materials: Structural and Acidity Properties

Schulman

Liu

2020

Materials

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Zeolites are generally defined as three-dimensional (3D) crystalline microporous aluminosilicates in which silicon (Si4+) and aluminum (Al3+) are coordinated tetrahedrally with oxygen to form large negative lattices and consequent Brønsted acidity. Two-dimensional (2D) zeolite nanosheets with single-unit-cell or near single-unit-cell thickness (~2–3 nm) represent an emerging type of zeolite material. The extremely thin slices of crystals in 2D zeolites produce high external surface areas (up to 50% of total surface area compared to ~2% in micron-sized 3D zeolite) and expose most of their active sites on external surfaces, enabling beneficial effects for the adsorption and reaction performance for processing bulky molecules. This review summarizes the structural properties of 2D layered precursors and 2D zeolite derivatives, as well as the acidity properties of 2D zeolite derivative structures, especially in connection to their 3D conventional zeolite analogues’ structural and compositional properties. The timeline of the synthesis and recognition of 2D zeolites, as well as the structure and composition properties of each 2D zeolite, are discussed initially. The qualitative and quantitative measurements on the acid site type, strength, and accessibility of 2D zeolites are then presented. Future research and development directions to advance understanding of 2D zeolite materials are also discussed.

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confidence: 71%

Section: Acidity Characterization For 2d Mww Zeolitesmentioning

confidence: 98%

Two-Dimensional Zeolite Materials: Structural and Acidity Properties

Schulman

Liu

2020

Materials

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“…As a main co-product in biodiesel production, glycerol is an important renewable resource derived from biomass [3][4][5][6]. Despite many applications in cosmetics, pharmaceuticals, and the tobacco industry, after expensive purification processes, glycerol production surplus is still a big problem [7,8]. In this context, upgrading glycerol to value-added chemicals becomes an urgent task, but with a bright future.…”

Section: Introductionmentioning

confidence: 99%

Nanosheet MFI Zeolites for Gas Phase Glycerol Dehydration to Acrolein

Shan

Zhu

et al. 2019

Catalysts

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To overcome the rapid deactivation of conventional ZSM-5, novel nanosheet MFI zeolites, with different Si/Al molar ratios were well fabricated. It was found that Si/Al molar ratios, do not just affect acid properties, but also determine the morphologies of nanosheet MFI zeolites by changing a-c plane areas of zeolite nanosheets. In reaction of gas phase glycerol dehydration to acrolein, the nanosheet MFI zeolites were much more active and stable than conventional ZSM-5 catalysts, owing to their suitable acidity and unique nanosheet structure. For nanosheet MFI zeolite, with Si/Al = 50 (NMZ-50), the conversion of glycerol is higher than 99% in the initial 12 h, with an acrolein selectivity of 86.6%, better than most previous reports. This superior stability of NMZ-50 can be ascribed to its low coke deposition rate and improved coke tolerance capacity. Additionally, it is interesting to find that Al contents do not just simply affect acid properties, but also determine morphologies of nanosheet MFI zeolites, and thus influence catalytic performance.

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“…The particular structure of the zeolite MCM-22 holds out interesting opportunities for modification by different methods like dealumination [13][14][15][16], change in the Si/Al ratio [17,18], etc. In the present work modified MCM-22 zeolites with varying composition of the building lattice elements and diverse number and strength of the acid sites were used for the selective transformation of EB in presence of m-xylene at high temperature and atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%