Caracterização termogravimétrica e espectroscópica das propriedades ácidas da zeólita ZSM-22

Loiola, Adonay R.; Andrade, João Sousa; Sasaki, J. M.; Silva, L. R. D. da; Nassar, Eduardo J.

doi:10.1590/s0366-69132010000300007

Cited by 7 publications

(2 citation statements)

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“…1. All zeolites exhibited XRD patterns of highly crystalline materials, exhibiting all characteristic peaks for each structure described in the literature, ZSM-22 (JCPDS [29], FER (JCPDS 44-0104) [30], and ZSM-5 (JCPDS 42-0023) [30]. The catalysts presented type I isotherms, exhibiting large amounts of N 2 adsorbed in the range of P/P 0 <0.1, and modest adsorption in the range of medium to high relative pressures, P/P 0 >0.1, indicating the predominantly microporous nature of the zeolites [28,31].…”

Section: Resultsmentioning

confidence: 81%

Thermo-catalytic degradation of PE and UHMWPE over zeolites with different pore systems and textural properties

et al. 2020

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The thermo-catalytic degradation of polyethylene (PE) and ultra-high molecular weight polyethylene (UHMWPE) was studied in the presence of zeolites (ZSM-5, ZSM-22, and ferrierite) with different pore systems and textural properties. The zeolites were physically mixed with polymers in the proportion of 30 wt% and submitted to thermogravimetric analysis at heating rates of 5, 10, 20, and 30 °C.min-1. The activation energy of the degradation process was determined using the Flynn-Wall-Ozawa method. The addition of zeolites to polymers has considerably reduced the temperature of degradation. ZSM-22 demonstrated greater efficiency in the degradation of PE because it has a smaller crystallite size, promoting a shorter diffusional path for the polymer fragments coming from the surface. Ferrierite showed a lower energy level in the degradation of UHMWPE, showing the need for synergy between the accessibility of the structure and acidity of the catalyst to promote the cracking of this polymer.

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Section: Resultsmentioning

confidence: 81%

Thermo-catalytic degradation of PE and UHMWPE over zeolites with different pore systems and textural properties

et al. 2020

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“…Another application of zeolites is its use for ion-exchange and water softening [19,20]. Ions such as Ca 2+ can be exchanged with Na + already present in the zeolites, thus removing these ions from water.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Diffusivity in Porous Solids: Levitation Effect

Nag¹,

Yashonath²

2020

Zeolites - New Challenges

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Fluids confined to zeolites and other porous solids exhibit many distinct properties. One such property is the diffusivity, which exhibits anomalous dependence on the size of the guest molecule confined to the pore. This is termed the levitation effect. A diffusivity maximum as a function of the diameter of the guest is seen. The diameter for which the guest has maximum diffusivity is seen to be associated with a minimum in the activation energy. The existence of similar behavior in other porous solids, framework flexibility, and effect of temperature are discussed. Experimental verification of the existence of the anomalous maximum is then discussed. Diffusion of n-hexane and its isomers in zeolite NaY are then discussed in detail. The reduction in the end-to-end length of n-hexane while passing through the 12-ring window and the reasons for the same are discussed. Section 3 discusses possible observations of size-dependent maximum in other condensed matter systems.

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