Generation of protonic acid sites from pentane on the surfaces of Pt/SO42−-ZrO2 and Zn/H-ZSM5 evidenced by IR study of adsorbed pyridine

Triwahyono, Sugeng; Jalil, Aishah Abdul; Musthofa, Malik

doi:10.1016/j.apcata.2009.10.019

Cited by 37 publications

(13 citation statements)

References 9 publications

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“…The peak at 1450 cm 21 is ascribed to pyridine adsorbed on Lewis acid sites, and the peak at 1545 cm 21 is ascribed to pyridine adsorbed on Brønsted acid sites as pyridinium ions. 34,35 The spectra show that both Zn The disappearance of the peak at 1450 cm 21 in the spectrum of the used sample indicated that some alkaline substances were absorbed on the Lewis acid sites in the catalytic run, which prevented the dehydration of 2-aminophenylethanol to enamine. Meanwhile, the absorbed alkaline substances as carbonaceous deposits, confirmed by TEM, also masked the active species ZnAl 2 O 4 by blocking the dehydrogenation of imine to phenylacetonitrile, which is the rate determining step of the process, and led to a decrease in the selectivity towards the phenylacetonitrile and deactivation of the catalyst.…”

Section: Characterization Of Catalystsmentioning

confidence: 98%

Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Zhang

Zhao

2012

RSC Adv.

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A novel method for the synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn 30.1 Cr 4.3 /c-Al 2 O 3 was established. A yield as high as 87.9% was received when the reaction was conducted on a fixed-bed reactor dosed with 30 ml (21 g) catalyst at 693 K under ammonia at atmospheric pressure by keeping the liquid velocity of styrene epoxide diluted with toluene (styrene oxide : toluene = 20 : 80 (m : m)) at 0.2 ml min 21 and the gas velocity of ammonia at 300 ml min 21 . The lifetime of the catalyst was evaluated and the activity of the catalyst could be recovered by continuously blowing air into the fixed-bed at 723 K for 3.5 h online. The catalyst was characterized by XRD, XPS, TEM and IR of adsorbed pyridine. The characterization results indicated that the dehydration reaction in the tandem reaction mainly took place on the Lewis acid sites and revealed that ZnAl 2 O 4 is the active species for the dehydrogenation of imine to nitrile. The doping of chromium on to the c-Al 2 O 3 supported zinc catalyst Zn 29.9 /c-Al 2 O 3 could diminish the size of ZnAl 2 O 4 crystallites, which is in favor of the dehydrogenation reaction. The deactivation of the catalyst is due to the carbonaceous deposits generated from the chemical adsorption of some alkaline substances in the catalytic run.

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Section: Characterization Of Catalystsmentioning

confidence: 98%

Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Zhang

Zhao

2012

RSC Adv.

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“…The hydrogen atoms spillover onto the support (ZrO 2 ) and undergo surface diffusion reaching to Lewis acid sites where the hydrogen atoms can release an electron, forming a proton. The bands corresponding to Brønsted and Lewis sites were observed at 1542 and 1450 cm À1 , 4,37,38 respectively, which were used to follow the dynamics of acid sites. The peak intensity for Brønsted and Lewis acid sites are shown in Fig.…”

Section: The Reducibility Of Catalystsmentioning

confidence: 99%

Structure–activity relationships of Cu–ZrO₂ catalysts for CO₂ hydrogenation to methanol: interaction effects and reaction mechanism

et al. 2017

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“…Both the experimental and theoretical calculation results suggest that transient BAS was generated during propene aromatization over Zn-modified HZSM-5. Currently, the dissociative adsorption behavior of Zn-modified zeolites has been reported in several studies with the molecules of hydrogen, methane, ethane, and propane. − In the same studies, the formation of transient BAS was shown with in situ diffuse reflectance FTIR spectra (DRIFT), as the consequence of the dissociative adsorption of molecular hydrogen, methane, ethane, and propane. However, to the best of our knowledge, the dissociative adsorption of propene on Zn-modified zeolite has seldom been mentioned in the literature so far.…”

Section: Resultsmentioning

confidence: 96%

Transient Brønsted Acid Sites in Propene Aromatization over Zn-Modified HZSM-5 Detected by Operando Dual-Beam FTIR

et al. 2019

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An operando dual-beam Fourier transform infrared spectrometer was developed to identify the transient Brønsted acid sites (BAS) in propene aromatization over acidic HZSM-5 and Zn-modified HZSM-5 catalysts under real reaction conditions. The eliminated signals include gas-phase molecular vibrations and heat irradiation at reaction temperatures. We directly observed that the initial activation of propene over Zn2+ of Zn-modified HZSM-5 generated a substantial number of transient BAS, which serve as active sites for the subsequent aromatization reactions. Moreover, during the propene aromatization process, the desorption of aromatic precursors over the Zn2+ of Zn/HZSM-5 is easier than that over the H+ of HZSM-5, resulting in an enhanced aromatics productivity. A density functional theory calculation certified the priority of the metallic Zn2+ sites over BAS in the competitive activation of propene molecules. The generation of transient BAS is energetically favorable.

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Generation of protonic acid sites from pentane on the surfaces of Pt/SO42−-ZrO2 and Zn/H-ZSM5 evidenced by IR study of adsorbed pyridine

Cited by 37 publications

References 9 publications

Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Structure–activity relationships of Cu–ZrO₂ catalysts for CO₂ hydrogenation to methanol: interaction effects and reaction mechanism

Transient Brønsted Acid Sites in Propene Aromatization over Zn-Modified HZSM-5 Detected by Operando Dual-Beam FTIR

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Generation of protonic acid sites from pentane on the surfaces of Pt/SO42−-ZrO2 and Zn/H-ZSM5 evidenced by IR study of adsorbed pyridine

Cited by 37 publications

References 9 publications

Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Synthesis of phenylacetonitrile by amination of styrene oxide catalyzed by a bimetallic catalyst Zn30.1Cr4.3/γ-Al2O3

Structure–activity relationships of Cu–ZrO2 catalysts for CO2 hydrogenation to methanol: interaction effects and reaction mechanism

Transient Brønsted Acid Sites in Propene Aromatization over Zn-Modified HZSM-5 Detected by Operando Dual-Beam FTIR

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Structure–activity relationships of Cu–ZrO₂ catalysts for CO₂ hydrogenation to methanol: interaction effects and reaction mechanism