Superiority of ZrO2 surface enrichment on ZSM-5 zeolites in n-pentane catalytic cracking to produce light olefins

Hou, Xu; Zhu, Wenjun; Tian, Yajie; Qiu, Yuan; Diao, Zhenheng; Feng, Fuxiang; Zhang, Xiangwen; Liu, Guozhu

doi:10.1016/j.micromeso.2018.09.019

Cited by 23 publications

(18 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increasing the %Zr Exp from HZZR1 (1.9 wt.%) to HZZR2 (2.6 wt.%) decreased the LAS/BAS ratio from 0.13 to 0.11. These differences may be the result of the interaction of the incorporated Zr species with the LAS present in the HZ zeolite, which increased with an increase in %Zr Exp [12,27,35] . However, the LAS/BAS ratio increased slightly to 0.13 and 0.14 for the HZZR3 (4.0 wt.%) and HZZR4 (8.2 wt.%) zeolites, respectively, suggesting a decrease in the proportion of BAS in relation to LAS.…”

Section: Resultsmentioning

confidence: 95%

“…Although the formation of zirconia was not confirmed by the XRD results of the HZZR1, HZZR2, DS02ZR1, DS02ZR2, DS04ZR1 and DS04ZR2 zeolites, its presence cannot be excluded. The UV‐vis‐DRS analysis (Figure 2) showed absorption bands beyond 220 nm, suggesting the presence of highly dispersed ZrO 2 regions or poorly crystalline oxide particles, [65,66,69,71] and detection in this region is beyond the limits of the powder XRD technique [12,31] . Additionally, the overlap between the diffraction peaks of the zeolite and t‐ZrO 2 may disguise the presence of oxide in the XRD analysis [28,32,35] …”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] Intrinsically, these materials mainly exhibit Brønsted acid sites (BAS) because of their negatively charged framework composed of AlO 4 À tetrahedrons balanced by protons (H + ). [4,5] Among zeolites, H-ZSM-5 is an important catalyst and has been successfully employed in reactions such as aromatization [6,7] isomerization, [8] esterification, [9,10] alkylation, [11] and catalytic cracking, [12] which require strong acid sites. However, one shortcoming of the ZSM-5 as a catalyst is the small size of its pores; the straight [010] or sinusoidal [100] 10-ring apertures are approximately 5.1-5.6 Å.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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%

Section: Introductionmentioning

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

show abstract

“…The NH 3 ‐TPD process was applied and the profiles are displayed in Figure 7. For each sample, two NH 3 desorption peaks could be observed at the range of 100–250°C and 300–500°C, corresponding to the weak acid sites and strong acid sites of HZSM‐5, respectively 29,30 . It could be evidently shown that as the content of TEOS increases, that is, with the ratio of HZSM‐5/TEOS decreased from 1:0.5 to 1:4, the total acid amount decreased dramatically.…”

Section: Resultsmentioning

confidence: 95%

Core‐shell structured HZSM‐5@mesoSiO₂ catalysts with tunable shell thickness for efficient n‐butane catalytic cracking

Yang

Chen

et al. 2021

AIChE Journal

View full text Add to dashboard Cite

A series of core‐shell HZSM‐5@mesoSiO2 with tunable shell thickness from 10 to 70 nm was prepared and studied for n‐butane catalytic cracking. With introducing of SiO2 shell, the catalytic performance of HZSM‐5@mesoSiO2 was largely enhanced, and n‐butane conversion rate per Al site reached to 2.43 min−1 over HZSM‐5@mesoSiO2(1:4) at 675°C which is nearly twice to that of HZSM‐5 (1.34 min−1). The diffusion property of n‐butane over as‐prepared sample was quantified by measuring the diffusional time constants using zero length column chromatography technique (ZLC). Combining with chemical reaction kinetic analysis, the quantitative relationship between diffusion property and catalytic performance was effectively established for the first time in n‐butane catalytic cracking. Positive linear correlation between diffusional time constant (D/R2) and n‐butane conversion rate per Al site could be found, which confirms that diffusion enhancement by hierarchical structure is an effective strategy to improve the activity of HZSM‐5 in catalytic cracking.

show abstract

“…Generally, Py-IR spectrums of samples give four peaks at around 1450, 1485, 1540 and 1600 cm −1 . The band at 1540 and 1485 cm −1 is assigned to the pyridinium ions formed by pyridine adsorbed on BAS, and the band at 1450, 1485 and 1600 cm −1 results from coordinated pyridine on LAS [31] [32] [33]. The ratio of BAS and LAS are calculated using the peak area at 1540 and 1450 cm −1 , respectively, and summarized in Table 2.…”

Section: Aciditymentioning

confidence: 99%

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

Cen¹,

Yang²,

Zhu³

et al. 2021

MSCE

View full text Add to dashboard Cite

Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600˚C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.

show abstract

Superiority of ZrO2 surface enrichment on ZSM-5 zeolites in n-pentane catalytic cracking to produce light olefins

Cited by 23 publications

References 51 publications

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

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

Core‐shell structured HZSM‐5@mesoSiO₂ catalysts with tunable shell thickness for efficient n‐butane catalytic cracking

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

Contact Info

Product

Resources

About

Superiority of ZrO2 surface enrichment on ZSM-5 zeolites in n-pentane catalytic cracking to produce light olefins

Cited by 23 publications

References 51 publications

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

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

Core‐shell structured HZSM‐5@mesoSiO2 catalysts with tunable shell thickness for efficient n‐butane catalytic cracking

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

Contact Info

Product

Resources

About

Core‐shell structured HZSM‐5@mesoSiO₂ catalysts with tunable shell thickness for efficient n‐butane catalytic cracking