scholarly journals Determination of active sites during gasification of biomass char with CO2 using temperature-programmed desorption. Part 2: Influence of ash components

Fuel ◽  
2020 ◽  
Vol 267 ◽  
pp. 117179 ◽  
Author(s):  
Sonia Rincón Prat ◽  
Christoph Schneider ◽  
Thomas Kolb
Keyword(s):  
Active Sites ◽  
Temperature Programmed Desorption ◽  
Biomass Char ◽  
Temperature Programmed

scholarly journals In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 807
Author(s):  
Zen Maeno ◽  
Xiaopeng Wu ◽  
Shunsaku Yasumura ◽  
Takashi Toyao ◽  
Yasuharu Kanda ◽  
...  
Keyword(s):  
Active Sites ◽  
Temperature Programmed Desorption ◽  
X Ray Diffraction ◽  
Zeolite Framework ◽  
X Ray ◽  
Catalytic Activities ◽  
Ethane Dehydrogenation ◽  
Temperature Programmed

In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI (SiO2/Al2O3 = 22.3), In-MOR (SiO2/Al2O3 = 20), and In-BEA (SiO2/Al2O3 = 25)) and different SiO2/Al2O3 ratios (In-CHA(Al-rich) (SiO2/Al2O3 = 13.7)). Their catalytic activities in nonoxidative ethane dehydrogenation were compared. Among the tested catalysts, In-CHA(Al-rich) provided the highest conversion. From kinetic experiments and in-situ Fourier transform infrared (FTIR) spectroscopy, [InH2]+ ions are formed regardless of SiO2/Al2O3 ratio, serving as the active sites.

scholarly journals Aktive Zentren in CaNaX und NiNaX-Zeolithen / Active Sites in CaNaX and NiNaX Zeolites

1977 ◽  
Vol 32 (7) ◽  
pp. 790-794 ◽  
Author(s):  
Johannes Latzel ◽  
Heinrich Noller
Keyword(s):  
Active Sites ◽  
Temperature Programmed Desorption ◽  
Desorption Peak ◽  
Pyridine Adsorption ◽  
Desorption Temperature ◽  
Temperature Programmed ◽  
Special Case

Temperature programmed desorption of pyridine and benzene was carried out on NaX-13, CaNaX and NiNaX. This was correlated with IR investigation of pyridine adsorption according to WARD3 and with microcatalytic investigations of 2-butanol dehydration and butene isomerisation. Pyridine showed three definite desorption maxima for each of the three zeolites. While the catalytically inactive NaX-13 desorbed pyridine up to 385 °C, the comparable desorption maxima of the active CaNaX and NiNaX were situated at 490 and 470 °C, respectively. IR investigations showed zeolitic cations for these adsorption centres (bands at 1443-1444,1443-1445,1447-1448 cm-1). The lower desorption temperature of the system pyridine/NiNaX, compared with CaNaX, is incompatible with the higher acidity of Ni2+ and the higher IR band level, while the desorption temperature on NaX-13 and CaNaX is conform with the acidity of the ions and the IR band. Benzene on NiNaX behaves in the same way as on NaX-13 (highest desorption temperature 160 °C) while a desorption peak still occurs at 375 °C on CaNaX. The special case of NiNaX is explained by migration of the Ni2+ into the sodalite cave.

Determination of ion-exchanged Co2+ cation in Co-ZSM-5 by temperature-programmed desorption

1997 ◽  
Vol 12 (1-3) ◽  
pp. 21-24 ◽  
Author(s):  
Chul Wee Lee ◽  
Paul Joe Chong ◽  
Young Chul Lee ◽  
Chong Shik Chin ◽  
Larry Kevan
Keyword(s):  
Temperature Programmed Desorption ◽  
Temperature Programmed

scholarly journals Comparative study of the active sites in zeolites by different probe molecules

2005 ◽  
Vol 70 (3) ◽  
pp. 457-474 ◽  
Author(s):  
Vera Dondur ◽  
Vesna Rakic ◽  
Ljiljana Damjanovic ◽  
Aline Auroux
Keyword(s):  
Comparative Study ◽  
Active Sites ◽  
Temperature Programmed Desorption ◽  
Acid Sites ◽  
Probe Molecules ◽  
Adsorption Calorimetry ◽  
Temperature Programmed ◽  
First Time

This review summarizes some of the recently published results concerning the acid sites in the zeolites ZSM-5 and Y studied by temperature-programmed desorption (TPD) and adsorption calorimetry using different probe molecules NH3, CO, N2O and n-hexane. For the first time it has been shown that the acid sites in hydrated zeolites are accessible for n-hexane adsorption.

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