Effect of the degree and type of the dealumination method on the structural, compositional and acidic characteristics of H-ZSM-5 zeolites

Triantafillidis, Costas S.; Vlessidis, Athanasios G.; Nalbandian, L.; Evmiridis, Nicholaos P.

doi:10.1016/s1387-1811(01)00399-7

Cited by 267 publications

(170 citation statements)

References 73 publications

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“…Because the samples were synthesized at the same synthesis condition except the variety of template, the difference between acidity may be caused by the different templates we used. It has been shown [29] that the number of acid sites that corresponds to the high-temperature desorption peak of NH 3 -TPD corresponds to the framework Al atoms of fresh HZSM-5 zeolites. Although the Si/Al ratios of the as-synthesized The cracking of n-hexane was performed on a pulse reaction device at 773 K with an on-line GC for product analysis.…”

Section: Acidity Of Samplesmentioning

confidence: 99%

Difference of ZSM-5 zeolites synthesized with various templates

et al. 2004

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Section: Acidity Of Samplesmentioning

confidence: 99%

Difference of ZSM-5 zeolites synthesized with various templates

et al. 2004

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“…Analogous to CO 2 , H 2 O may also be a good reagent that removes coke accumulation on the zeolite catalyst by the reforming reaction (H 2 O+CHv (v=0-4)=CO+H 2 ). However, the addition of water may destroy the structure of the zeolite at high temperatures [18]. In this paper, we also studied the effect of water addition into the feed on the performance of a 0.7%K/ZSM-5 catalyst in the process of butene catalytic cracking.…”

Section: Introductionmentioning

confidence: 99%

Butene Catalytic Cracking to Propene and Ethene over Potassium Modified ZSM-5 Catalysts

et al. 2005

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Catalytic cracking of butene over potassium modified ZSM-5 catalysts was carried out in a fixed-bed microreactor. By increasing the K loading on the ZSM-5, butene conversion and ethene selectivity decreased almost linearly, while propene selectivity increased first, then passed through a maximum (about 50% selectivity) with the addition of ca. 0.7-1.0% K, and then decreased slowly with further increasing of the K loading. The reaction conditions were 620°C, WHSV 3.5 h )1 , 0.1 MPa 1-butene partial pressure and 1 h of time on stream. Both by potassium modification of the ZSM-5 zeolite and by N 2 addition in the butene feed could enhance the selectivity towards propene effectively, but the catalyst stability did not show any improvement. On the other hand, addition of water to the butene feed could not only increase the butene conversion, but also improve the stability of the 0.7%K/ZSM-5 catalyst due to the effective removal of the coke formed, as demonstrated by the TPO spectra. XRD results indicated that the ZSM-5 structure of the 0.07% K/ZSM-5 catalyst was not destroyed even under this serious condition of adding water at 620°C.

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“…Kumar et al [22] also found mild dealumination by AHFS treatment. Accordingly, Triantafillidis et al [23] reported that AHFS treatment was appropriate for preparation of moderately dealuminated H-ZSM5 samples, which were free from extra framework Al.…”

Section: Resultsmentioning

confidence: 99%

Effect of different acidity modifications on the activity and selectivity on H-ZSM5 zeolites in n-butene isomerization

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2014

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H-ZSM-5 was modified by silylation [tetraethylorthosilicate (TEOS) and triaminopropyltriethoxysilane], alkali (NaOH), acid (HCl) and ammoniumhexafluorosilicate (AHFS) treatments. The parent and modified zeolite forms were tested in n-butene isomerization. Modifications affected total acidities, the strength of the acid sites, pore sizes and surface areas of the H-ZSM-5 differently. The modifications decreased the conversion obtained by the parent catalyst. TEOS and alkali modifications did not promote formation of isobutene. Pre-alkali treatment before acid treatment increased selectivity to isobutene from 56.0 to 66.7 %, while conversion changed a little, it dropped from 52 to 50 %. AHFS modification provided the highest enhancement in selectivity to isobutene (87.5 %) for which n-butene conversion was dropped by about 10 % compared to H-ZSM-5. This was attributed to a slight modification of the pore size and to the reduction in strong and weak acid sites and generation of new Lewis acid sites.

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Effect of the degree and type of the dealumination method on the structural, compositional and acidic characteristics of H-ZSM-5 zeolites

Cited by 267 publications

References 73 publications

Difference of ZSM-5 zeolites synthesized with various templates

Difference of ZSM-5 zeolites synthesized with various templates

Butene Catalytic Cracking to Propene and Ethene over Potassium Modified ZSM-5 Catalysts

Effect of different acidity modifications on the activity and selectivity on H-ZSM5 zeolites in n-butene isomerization

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