Factors affecting the selectivity of the aromatization of light alkanes on modified ZSM-5 catalysts

Scurrell, Michael S.

doi:10.1016/s0166-9834(00)80384-x

Cited by 95 publications

(47 citation statements)

References 8 publications

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“…The introduction of modifiers can enhance the catalytic performance. It has been shown that the combination of ZSM-5 with zinc or gallium cations is an effective catalyst for the conversion of lower weight paraffins into aromatics [3,14,15]. However, little research has been done concerning the effects of alkaline earth metal addition on the performance of ZSM-5 aromatization catalysts, especially for the role of two combined promoters [16].…”

Section: Introductionmentioning

confidence: 99%

Effects of Zinc and Magnesium Addition to ZSM-5 on the Catalytic Performances in 1-hexene Aromatization Reaction

Liu

Zhu

et al. 2011

Catal Lett

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Effects of Zn and Mg addition on the catalytic performances of ZSM-5 in 1-hexene aromatization and isomerization were investigated. NH 3 -TPD and Pyridine-IR spectra revealed that the addition of Zn could increase the Lewis acidity amount of the support. And the catalytic aromatization activity was improved. Introduction of Mg resulted in a decrease of total acidity, especially for Br/ nsted acid sites which was beneficial for the high iso-paraffin and liquid product yield. The optimal modification way on ZSM-5 was obtained as addition of Mg with successive Zn introduction which may lead to the presence of Zn species inside of the zeolite channel evidenced by XPS results. The close proximity of Zn species to Br/nsted acid sites may enhance the synergy effect between them in the aromatization reaction. The optimized Zn-Mg/HZSM-5 sample also exhibited good catalytic performance when using FCC gasoline as reactant.

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Section: Introductionmentioning

confidence: 99%

Effects of Zinc and Magnesium Addition to ZSM-5 on the Catalytic Performances in 1-hexene Aromatization Reaction

Liu

Zhu

et al. 2011

Catal Lett

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“…In these composite catalysts, comprising acidic and oxidic components, some reaction steps are catalyzed by the acid sites and some by Ga 3? or Zn 2? sites, and the selectivity to aromatics is significantly higher for catalysts containing Ga 3? or Zn 2? than with metal cation-free H-ZSM-5 [3,[8][9][10][11][12][13][14]. There are general methods by which gallium and zinc oxides can be incorporated into zeolites, for example physical mixing, ion exchange, impregnation.…”

Section: Introductionmentioning

confidence: 99%

Aromatization of Isobutene Using H-ZSM-5/Oxide Composite Catalysts

Al-Otaibi

Hutchings

2009

Catal Lett

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Aromatization of isobutene was investigated using zeolite H-ZSM-5 (Si/Al = 30) as well as physical mixtures of H-ZSM-5 with metal oxides (Ga 2 O 3 , ZnO and CuO). The study was aimed at determining the effect on the selectivity to aromatic products by introducing an oxide/zeolite interface. Of the three oxides, ZnO was found to enhance the yield of aromatic products with the highest aromatic selectivity being attained with ZnO/H-ZSM-5 (1:2 weight ratio). The addition of Ga 2 O 3 had very little effect and the addition of CuO was not found to be beneficial.

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“…Particular research efforts have been directed at zinc-or galliumcontaining zeolites of the ZSM-5 type since these catalysts are, in favorable form, capable of permitting the achievement of high BTX (Benzene, Toluene and Xylene) selectivities [1,2,[4][5][6][7]. A recent assessment of the performances of these types of…”

Section: Introductionmentioning

confidence: 99%

“…There is general acceptance [1,2,7] that the major role of the elements zinc or gallium is to accelerate this reaction of surface hydrogen, formed via the dehydrogenation/ dehydrocyclization processes involved as key steps in the aromatization of alkanes via alkenic intermediates. In the absence of an efficient hydrogen removal step, there is a marked tendency for it to participate instead in hydrogen transfer processes, placing a severe upper limit on BTX selectivity that can be achieved [4].…”

mentioning

confidence: 99%

Light alkane aromatization over modified Zn-ZSM-5 catalysts: characterization of the catalysts by hydrogen/deuterium isotope exchange

Frey

Lubango

Scurrell

et al. 2011

Reac Kinet Mech Cat

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The selectivity obtained in the aromatization of propane over Zn-ZSM-5-based catalysts (Si/Al nominal ratio = 35) increased from about 69% (carbon basis) to 74-91% when a second transition metal ion is introduced into the catalyst. The effect, previously reported for the case of Fe 3? ions, has now been shown to be more general and is seen also for the ions of chromium, cobalt or manganese. It is likely that these ions are present under aromatization conditions in a partially reduced state. H 2 /D 2 isotope exchange rates show large enhancements on the reduced Fe-Zn/ZSM-5 and Co-Zn/ZSM-5 samples. This aspect of aromatization catalysis has not been reported before.Keywords Aromatization Á Alkanes Á Zinc-zeolites Á Transition metal ions Á H 2 /D 2 exchange IntroductionLight alkane aromatization over zeolite-based catalysts is well known [1, 2] and has been applied to the upgrading of liquefied petroleum gas using the BP/UOP Cyclar Process [3]. Particular research efforts have been directed at zinc-or galliumcontaining zeolites of the ZSM-5 type since these catalysts are, in favorable form, capable of permitting the achievement of high BTX (Benzene, Toluene and Xylene) selectivities [1,2,[4][5][6][7]. A recent assessment of the performances of these types of

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Factors affecting the selectivity of the aromatization of light alkanes on modified ZSM-5 catalysts

Cited by 95 publications

References 8 publications

Effects of Zinc and Magnesium Addition to ZSM-5 on the Catalytic Performances in 1-hexene Aromatization Reaction

Effects of Zinc and Magnesium Addition to ZSM-5 on the Catalytic Performances in 1-hexene Aromatization Reaction

Aromatization of Isobutene Using H-ZSM-5/Oxide Composite Catalysts

Light alkane aromatization over modified Zn-ZSM-5 catalysts: characterization of the catalysts by hydrogen/deuterium isotope exchange

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