Acidity of Beta zeolite determined by TPD of ammonia and ethylbenzene disproportionation

Camiloti, A.M; Jahn, S. L.; Velasco, Nelson D.; Moura, Luiz Fernando de; Cardoso, Dilson

doi:10.1016/s0926-860x(98)00418-9

Cited by 92 publications

(52 citation statements)

References 14 publications

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“…The total acid sites and the ratio of Lewis acid site to Brønsted acid site (L/B ratio) are presented in Table 1. The peak temperature and L/B ratio were determined by deconvolution and subse- [28][29][30][31]. Fresh calcined ZSM-5-Zn catalyst had higher total acid sites than fresh calcined ZSM-5 catalyst.…”

Section: -1 Surface Acidity and Carbon Content Analysismentioning

confidence: 99%

Catalytic cracking of inedible camelina oils to hydrocarbon fuels over bifunctional Zn/ZSM-5 catalysts

Zhao

Wei

Julson

et al. 2015

Korean J. Chem. Eng.

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Catalytic cracking of camelina oils to hydrocarbon fuels over ZSM-5 and ZSM-5 impregnated with Zn 2+ (named bifunctional catalyst) was individually carried out at 500 o C using a tubular fixed-bed reactor. Fresh and used catalysts were characterized by ammonia temperature-programmed desorption (NH 3 -TPD), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and nitrogen isothermal adsorption/desorption micropore analyzer. The effect of catalysts on the yield rate and qualities of products was discussed. The loading of Zn 2+ to ZSM-5 provided additional acid sites and increased the ratio of Lewis acid site to Brøn-sted acid site. BET results revealed that the surface area and pore volume of the catalyst decreased after ZSM-5 was impregnated with zinc, while the pore size increased. When using the bifunctional catalyst, the pH value and heating value of upgraded camelina oils increased, while the oxygen content and moisture content decreased. Additionally, the yield rate of hydrocarbon fuels increased, while the density and oxygen content decreased. Because of a high content of fatty acids, the distillation residues of cracking oils might be recycled to the process to improve the hydrocarbon fuel yield rate.

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Section: -1 Surface Acidity and Carbon Content Analysismentioning

confidence: 99%

Catalytic cracking of inedible camelina oils to hydrocarbon fuels over bifunctional Zn/ZSM-5 catalysts

Zhao

Wei

Julson

et al. 2015

Korean J. Chem. Eng.

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“…Camiloti et al [17] employed TPD of ammonia to determine the acidity of zeolite Hb and found the NH 3 / Al ratios were equal to one, suggesting that every aluminum atom provides an accessible potential site. Nevertheless, using an estimation of acid site density from the Al content should be considered to provide a maximum value for the concentration of active surface sites, meaning that TOFs calculated correspond to minimum TOF values.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

A comparative study of gas phase esterification on solid acid catalysts

2007

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For the first time, a comprehensive comparison of the intrinsic activities of solid acid catalysts in terms of turnover frequency (TOF) is reported for the gas-phase esterification of acetic acid with methanol. The catalysts studied included a zeolite (Hb), two modified zirconias (sulfated zirconia, SZ; and tungstated zirconia, WZ), and an acidic resin-silica composite (Nafion/silica, SAC-13). Activities on a per weight basis decreased in the following order: Hb $ SAC-13 ) SZ > WZ at 130°C. However, on a rateper-site basis (TOF), all catalysts showed comparable activities. The TOF results suggest that the acid sites of these catalysts have similar capacity for effectively catalyzing esterification. All catalysts deactivated to a quasi-steady-state rate with TOS. Regeneration experiments suggested that catalyst deactivation was due mainly to site blockage by carbonaceous deposits. Selective poisoning experiments showed that the reaction predominately took place on Brønsted acid sites.

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“…Increasing the Si/Al ratio leads to the reduced number of mobile cations present and to the increase in the distance between the accessible hopping sites between one another. However, Y5.1 and M19 have lower electrical conductivity values than those of Y30 and M30, respectively, because of the excessive negative charge density of the zeolite framework, which can be attributed to a lower proton activity [17].…”

Section: Characterization Of Zeolitesmentioning

confidence: 98%

“…Table 2 lists the desorption temperatures of the samples. Since stronger acid sites desorb ammonia at higher temperatures [17][18][19], the shift of the peak to the higher temperatures as the aluminum content decreases (increasing of Si/Al ratio) of the Y and mordenite zeolites indicates an increase in the acid strength of the sites which can be attributed to a higher proton activity as a consequence of the lower negative charge density of the zeolite framework. for the ZSM-5 zeolites, the shift of the desorption peak to lower temperatures as the aluminum content decreases (increasing of Si/Al ratio) indicates a decrease in the acid strength of the sites which can be attributed to a lower proton activity as a consequence of the higher negative charge density of the zeolite framework.…”

Section: Characterization Of Zeolitesmentioning

confidence: 99%

“…3 The dielectric constant of ZSM-5, Y, and mordenite zeolites with various Si/Al ratios Fig. 4 Electrical conductivity sensitivity of ZSM-5, Y, and mordenite zeolites with various Si/Al ratios those of Y30 and M30, respectively; the higher negative charge density of the zeolite framework can be attributed to a lower proton activity [17]. The electrical conductivity sensitivity values, Δσ/σ N2 , and the dielectric constants, ε′/ε 0 , of the zeolites of various Si/Al ratios and frameworks are shown in Table 3.…”

Section: Characterization Of Zeolitesmentioning

confidence: 99%

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Electrical conductivity response and sensitivity of ZSM-5, Y, and mordenite zeolites towards ethanol vapor

Yimlamai

Niamlang

Chanthaanont

et al. 2011

Ionics

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This work is an attempt to search for highly selective sensing materials for ethanol vapor. The electrical conductivity response of ZSM-5, Y, and mordenite zeolites towards ethanol vapor have been investigated for the effects of the framework, the charge balancing cation type, and the Si/Al ratio. All zeolites were characterized using XRD, FT-IR, SEM, TGA, BET, and NH 3 -TPD techniques. For the effect of the zeolite framework type, H + Y has a higher electrical conductivity sensitivity value than that of H + MOR because of a greater pore volume and available surface area. For the effect of the charge balancing cation, all NH 4 + ZSM-5 zeolites (Si/Al=23, 50, 80, 280) show negative responses, whereas the H + Y zeolites (Si/Al=30, 60, 80) and the H + MOR zeolites (Si/Al=30, 200) show positive responses. These differing behaviors can be traced to the electrostatic field at the cation sites in zeolite micropores, and their hydrophilic-hydrophobic character, which affect the adsorption properties of the zeolites. For the effect of Si/Al ratio, the electrical conductivity sensitivity towards the ethanol decreases with increasing Si/Al ratio or decreasing Al content, and there is a lesser degree of interaction between ethanol molecules and the active sites of the zeolites due to its higher hydrophobicity and the lower amount of cations. However, the H + Y (Si/Al=5.1) and the H + MOR (Si/Al=19) zeolites have lower conductivity sensitivity than those of H + Y (Si/Al=30) and H + MOR (Si/Al=30), respectively. The interactions between the C 2 H 5 OH molecules and the zeolites with respect to the electrical conductivity sensitivity were investigated and verified through infrared spectroscopy.

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Acidity of Beta zeolite determined by TPD of ammonia and ethylbenzene disproportionation

Cited by 92 publications

References 14 publications

Catalytic cracking of inedible camelina oils to hydrocarbon fuels over bifunctional Zn/ZSM-5 catalysts

Catalytic cracking of inedible camelina oils to hydrocarbon fuels over bifunctional Zn/ZSM-5 catalysts

A comparative study of gas phase esterification on solid acid catalysts

Electrical conductivity response and sensitivity of ZSM-5, Y, and mordenite zeolites towards ethanol vapor

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