Zeolite FER

Combined TPD and theoretical investigation of CO desorption from Cu-K-FER zeolite... 

In this contribution the analysis of the TPD data obtained for Cu-K-FER zeolite is presented, considering the formation of carbonyl complexes on dual cation sites. 

Due to the presence of low-temperature desorption peak a new desorption site was included to phenomenological model of TPD experiments previously used for the description of the Cu-Na-FER samples [5], The fit of experimental TPD curves was performed in order to obtain adsorption energies and populations for individual site types sites denoted A (A1 pair), B (sites in P channel (A1 at T1 or T2)), C (sites in the M channel and intersection (A1 at T3 or T4)) [3] and D (newly introduced site). The new four-site model was able to reproduce experimental TPD curves (Figure 1). The desorption energy of site D is cu. 82 kJ.mol"1. This value is rather close to desorption energy of 84 kJ.mol"1 found for the site B , however, the desorption entropy obtained for sites B and D are rather different -70 J.K. mol 1 and -130 J.K. mol"1 for sites B and D , respectively. We propose that the desorption site D can be attributed to so-called heterogeneous dual-cation site, where the CO molecule is bonded between monovalent copper ion and potassium cation. The sum of the calculated populations of sites B and D (Figure 2) fits well previously published population of B site for the Cu-Na-FER zeolite [3], Because the population of C type sites was... 

Interaction of the CO molecule with CuX-FER zeolites (X is an alkali-metal or proton as a co-cation) was investigated by IR spectroscopy and DFT calculations. An absorption band at 2138 cm 1 observed in IR spectra of CO on CuK- and CuCs-FER zeolites was assigned to a new type of CO adsorption complex on heterogeneous dual cation sites. CO molecule interacts simultaneously with Cu+ and alkali metal cations (via C- and O-end, respectively) in this type of complex. Interaction of CO with the secondary (alkali metal) cation led to a slight destabilization of the carbonyl complex. 

Table Chemical composition of CuX-Fer zeolites and ion exchange conditions at RT...

In this work, an attempt is made to show the role of the different metal species present in Co and Co/Pd based FER zeolites, using UV-Vis and H2-TPR experiments, coupled with Temperature Programmed Surface Reaction (TPSR) tests. 

A Ni on FER zeolite B Enzyme immobilized on zeolite-Y C Zn particles (1 mm diameter)... 

Figure 3.24 FTIR spectra of H-FER zeolite (Zeolyst, Si/AI = 27.5) (a) after activation (b) after contact with iBN vapour, b-a subtraction spectrum.

CHARACTERIZATION AND ETHYLENE ADSORPTION PROPERTIES OF SILVER-LOADED FER ZEOLITE POTENTIALLY USED AS TRAP MATERIAL OF COLD-START HYDROCARBON EMISSION FROM VEHICLES... 

FER zeolite can be prepared by spontaneous crystallization under hydrothermal conditions from the reactant with molar composition of 0.5 THF (tetrahydrofuran)- 0.215Na2O Si02 0.05Al203 20H20. The influence of Si02/Al203 molar ratio, alkalinity, amount of template and reaction temperature was explored as well. 

To obtain reliable results with pyridine as a probe, one should pay attention to the experimental details, in particular one needs to ensure that weakly adsorbed species are removed. A standard procedure in the investigation of zeolites and other porous materials starts with the introduction of pyridine at a temperature of 423 K and a partial pressure of about 100 Pa. The goal of this step is to allow diffusion of pyridine vapor into the small pores. As exemplified in Figure 2.37, the pressure is essential for pyridine diffusion into the pores of FER zeolite, even at 573 K. 

Resini, C., Montanan, T., Nappi, L., Bagnasco, G., Turco, M., Busca, G., Bregani, R, Notaro M., and Rocchini, G. Selective catalytic rednction of NO by methane over Co-H-MFI AND Co-H-FER zeolite catalysts characterisation and catalytic activity. 5 Catal. 2003, 214, 179-190. 

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