Synthesis and characterization of isomorphously zirconium substituted Mobil Five (MFI) zeolite

Shah, Kishor Kr; Saikia, Jitu; Saikia, Durlov; Talukdar, Anup Kumar

doi:10.1016/j.matchemphys.2012.02.012

Cited by 13 publications

(6 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Through UV-vis-DR spectroscopy, it is possible to investigate the isolation degree and coordination environment of Zr species in zeolites. [28,31,32,[63][64][65] A strong absorbance band at approximately 200 nm was observed for all Zr-containing zeolites, which was not seen in the spectra of precursor zeolites (HZ, DS02, and DS04). This band is commonly assigned to catalytically active Zr species that are highly dispersed with tetrahedral coordination and indicates charge-transfer transitions between oxygen atoms and Zr 4 + ions.…”

Section: Resultsmentioning

confidence: 95%

“…The ultraviolet–visible diffuse reflectance spectroscopy (UV‐vis‐DRS) results of all studied zeolites are shown in Figure 2. Through UV‐vis‐DR spectroscopy, it is possible to investigate the isolation degree and coordination environment of Zr species in zeolites [28,31,32,63–65] . A strong absorbance band at approximately 200 nm was observed for all Zr‐containing zeolites, which was not seen in the spectra of precursor zeolites (HZ, DS02, and DS04).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Efficient Dry Impregnation of Zirconium into H‐ZSM‐5 Zeolites

2022

View full text Add to dashboard Cite

There is considerable interest in adjusting the acidity and pore architecture of zeolites. Herein, we present solventless incorporation of zirconium (∼2–10 wt.%) in a precursor and desilicated (0.2 and 0.4 mol L−1 NaOH) H‐ZSM‐5 zeolite. Infrared and UV‐vis‐DR spectroscopy confirmed the grafting of highly dispersed Zr in all the zeolites. XRD indicated the presence of ZrO2 in zeolites with higher Zr contents. The micropore volume of the precursor zeolite decreased by ∼10 %, suggesting the presence of Zr mainly on the external surface, while it decreased more than 20 % for the desilicated sample, suggesting Zr had access to the micropores at higher Zr contents. Infrared spectroscopy after pyridine adsorption provided evidence for the Brønsted and Lewis acid sites in all zeolites, but the Brønsted acid‐to‐Lewis acid site ratio decreased by >50 % depending on the Zr and NaOH concentrations. The presence of Zr critically changed the predominant nature of the acid sites of the desilicated zeolites.

show abstract

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Efficient Dry Impregnation of Zirconium into H‐ZSM‐5 Zeolites

2022

View full text Add to dashboard Cite

show abstract

“…FT-IR spectra (Figure S8) show that all of the samples have a band at 960 cm –1 , which can be attributed to formation of the Zr–O–Si bond . For the UV–vis spectra (Figure S9), both Zr-β and the treated Zr-β zeolite had a peak at 215 nm attributed to the tetrahedral framework site, ,, and there was no peak corresponding to a ZrO 2 species (234 nm). For the XPS spectra (Figure S10), the binding energies of Zr 3d 5/2 in Zr-β and the treated Zr-β zeolite are both 182.6 eV, higher than that of ZrO 2 (182.0 eV), which also indicates formation of a Zr–O–Si bond. ,, These results are consistent with our previously reported results for Zr-SBA-15 and Zr-β, proving that the heteroatom Zr presence of the treated Zr-β zeolite does not change in the dual-template treatment process and that Zr is still incorporated in the zeolite framework.…”

Section: Resultsmentioning

confidence: 99%

“…FT-IR spectra (Figure S8) show that all of the samples have a band at 960 cm −1 , which can be attributed to formation of the Zr−O−Si bond. 23 For the UV−vis spectra (Figure S9), both Zr-β and the treated Zr-β zeolite had a peak at 215 nm attributed to the tetrahedral framework site, 12,15,24 and there was no peak corresponding to a ZrO 2 species (234 nm). For the XPS spectra (Figure S10), the binding energies of Zr 3d 5/2 in Zr-β and the treated Zr-β zeolite are both 182.6 eV, higher than that of ZrO 2 (182.0 eV), which also indicates formation of a Zr−O−Si bond.…”

Section: Effect Of Surfactant Concentrationmentioning

confidence: 99%

Uniform Mesoporosity Development in Incorporated β Zeolite: Dual-Template Strategy

Dong

Wang

Yang

et al. 2022

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

The hierarchical porosity of zeolite is a key factor affecting its catalytic activity and stability for bulky molecules involved reactions. However, it is still challenging to introduce mesoporosity into heteroatom-incorporated zeolites in a facile manner while maintaining the catalytic activity. In this work, a strategy for mesoporosity development in incorporated zeolites based on two templates (TEAOH and surfactants) under hydrothermal conditions was proposed, and hierarchical Zr-incorporated β zeolite was successfully prepared and used to catalyze the ETB reaction. In this process, OH– etches the zeolite framework while TEA+ preserves the microporous structure and the surfactant as the mesoporogen. The mesopore size (2.1–3.2 nm) can be tailored by changing the alkyl chain length (C10–C16) of the surfactant. During the treatment, the chemical environment of Zr in Zr-β zeolite did not change and the amount of Lewis acid was increased, showing that the mesoporosity could improve the accessibility of active sites. The hierarchical Zr-β zeolite showed better catalytic performance than the parent Zr-β zeolite in the ethanol–acetaldehyde to butadiene reaction, the conversion of ethanol and acetaldehyde can reach 63.7%, and the selectivity of butadiene can reach 76.6%. The stability of hierarchical Zr-β zeolite is significantly higher than that of microporous Zr-β zeolite, whose conversion can be maintained at 35.0% and selectivity at 70.9% at TOS = 24 h. The mesoporosity can increase the capability of coke which mitigates the deactivation.

show abstract

“…36 They have widespread application in a wide range of reactions, especially in reactions requiring moderate acidity and oxidizing capabilities like hydrogenation, hydroxylation, oxidation or epoxidation. 37 Niobium compounds exhibit special properties not shown by the compounds of neighbouring elements in the periodic table. Some of them, like stability or strong metal support interaction (SMSI) and strong metal oxide support interaction (SMOSI), are very important for a good quality catalyst.…”

Section: Introductionmentioning

confidence: 99%