Temperature-Programmed Desorption of Ammonia with Readsorption Based on the Derived Theoretical Equation

Niwa, Miki; Katada, Naonobu; Sawa, Masahiko; Murakami, Yûichi

doi:10.1021/j100021a056

Cited by 166 publications

(129 citation statements)

References 6 publications

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“…ΔS consists of two entropy terms, ΔS (phase transformation) and ΔS (physical mixing), and the for mer ΔS due to the phase transformation, i.e., desorption, is almost equal to ΔS upon vaporization of liquid ammo nia. The dependence of peak temperature on the W/F ratio was an important evidence to experimentally con firm the equilibrium conditions of the ammonia TPD 3) . Entropy change upon desorption which equals to that of the vaporization implies that the translational energy only changes upon desorption, which sounds reason able for the physical chemistry of gaseous molecule.…”

Section: Introduction Measured Then a New Technique Of Irms-tpd Ismentioning

confidence: 96%

“…Fitting of the simu lated curve to the experimental TPD spectrum gives us the solutions of two parameters. This is the method of quantitative determination of number and strength of acid sites by means of ammonia TPD experiment 3) . Actually, the curve fitting can be carried our using an "Excel" software on a personal computer.…”

Section: Introduction Measured Then a New Technique Of Irms-tpd Ismentioning

confidence: 99%

See 1 more Smart Citation

Combined Method of Ammonia IRMS-TPD Experiment and DFT Calculation to Characterize Zeolite Acidity

Niwa

Katada

2009

J. Jpn. Petrol. Inst.

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Our recently developed potential characterization method for studying the zeolite acidity is reviewed. In this method, ammonia TPD is a principle technique and first the principle of the method was explained. In order to overcome the drawback existed in the usual TPD, IRMS-TPD method was developed, in which IR and MS were measured simultaneously to monitor the thermal behavior of ammonia molecules on the surface and in the gas phase. The developed method made it possible not only to measure the Brønsted and Lewis acid sites individu ally but also to clarify the distribution of Brønsted acid sites. In addition, DFT calculations were carried out to confirm the obtained information of the Brønsted acidity. Based on these studies, a new technique was devel oped by combining the IRMS-TPD experiment and DFT calculation to precisely characterize the zeolite acidity. Using the developed method, the modified Y zeolites active for the cracking of hydrocarbons were studied.

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Section: Introduction Measured Then a New Technique Of Irms-tpd Ismentioning

confidence: 96%

Section: Introduction Measured Then a New Technique Of Irms-tpd Ismentioning

confidence: 99%

Combined Method of Ammonia IRMS-TPD Experiment and DFT Calculation to Characterize Zeolite Acidity

Niwa

Katada

2009

J. Jpn. Petrol. Inst.

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“…The acid strength was also determined from the temperature of maximum peak (T max ) of the desorption peak concerned with the activation energy for ammonia desorption [35]. In general, the desorption peaks ranging from 350 • C to 550 • C are due to strong acid sites; on the other side, the peak of the weak acid sites or physically-adsorbed ammonia appeared at 150~250 • C [36]. The number of acid sites is reduced with decreasing Al content in the zeolite framework.…”

Section: Introductionmentioning

confidence: 99%

Highly Selective Catalytic Properties of HZSM-5 Zeolite in the Synthesis of Acetyl Triethyl Citrate by the Acetylation of Triethyl Citrate with Acetic Anhydride

et al. 2017

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Abstract:The catalytic activities of acid catalysts for the acetylation of triethyl citrate with acetic anhydride in the preparation of acetyl triethyl citrate were evaluated. Microporous zeolites such as HZSM-5 and HY zeolites catalysts were introduced as heterogeneous acid catalysts. HZSM-5 zeolite catalysts showed a high conversion of triethyl citrate and excellent selectivity of acetyl triethyl citrate. The catalytic activities of HZSM-5 zeolites were superior to those of the HY zeolites. In particular, the selectivity of acetyl triethyl citrate on HZSM-5 zeolites exceeded 95%. The moderate acid strength of HZSM-5 (Si/Al = 75) zeolite led to the highest catalytic activities among the HZSM-5 zeolite catalysts, which have various acid strengths.

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“…Therefore, almost all the acid sites were generated by the introduction of Fe 3+ or Al ions. proposed by Niwa et al [21]. Since the ΔH NH3 of CZ was higher than those of F1 or F4, the acid strength of Fe-MFI was lower than that of ZSM-5.…”

Section: Precise Control In Characteristics Of Nano-particulate Mfi-tmentioning

confidence: 86%

Precise Control in Characteristics of Nano-particulate MFI-Type Ferrisilicate and Their Catalysis in the Conversion of Dimethyl Ether into Light Olefins

Kobayashi¹,

Nakaya²,

Kanie³

et al. 2015

JESE-B

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This study reports the synthesis of size-controlled Fe-MFI (Fe-substituted zeolites with the MFI topology) and their catalytic performances for DTO (dimethyl ether-to-olefins) reaction. The amount of HCl and aging temperature were decisive factors to control the particle size of Fe-MFI in the range of 50 nm to 600 nm. The introduction of Fe 3+ ions into the zeolitic framework was confirmed by UV (ultraviolet)-visible spectroscopy. In addition, it was observed that the strength of acid site in prepared Fe-MFI was weaker than that of commercial ZSM-5. With decrease in the particle size, the amount of deposited coke decreased so that the catalyst life for the DTO reaction was well promoted. The present catalysts showed the higher light-olefin selectivity (C 2 = + C 3 = + C 4 = ) than commercial ZSM-5 catalysts mainly due to the suppression of the formation of paraffins; however, the Fe-MFI catalysts were deactivated rapidly because of their low activity for the cracking of alkenes.

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Temperature-Programmed Desorption of Ammonia with Readsorption Based on the Derived Theoretical Equation

Cited by 166 publications

References 6 publications

Combined Method of Ammonia IRMS-TPD Experiment and DFT Calculation to Characterize Zeolite Acidity

Combined Method of Ammonia IRMS-TPD Experiment and DFT Calculation to Characterize Zeolite Acidity

Highly Selective Catalytic Properties of HZSM-5 Zeolite in the Synthesis of Acetyl Triethyl Citrate by the Acetylation of Triethyl Citrate with Acetic Anhydride

Precise Control in Characteristics of Nano-particulate MFI-Type Ferrisilicate and Their Catalysis in the Conversion of Dimethyl Ether into Light Olefins

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