Fractal analysis at mesopore scale of modified USY zeolites by nitrogen adsorption: A classical thermodynamic approach

Autor: Yefferson-Stid Ruíz-Cardona, Luis-Ernesto Sandoval-Díaz, Carlos Alexander Trujillo, Jhon-Anderson Aragon-Quiroz, Andy-Rafael Domínguez-Monterroza
Rok vydání: 2017
Předmět:
Zdroj: Microporous and Mesoporous Materials. 237:260-267
ISSN: 1387-1811
DOI: 10.1016/j.micromeso.2016.08.030
Popis: The thermodynamic method of fractal analysis applied to N 2 adsorption data of porous solids (commonly known as Neimark-Kiselev or NK algorithm) is discussed. Two refinements are shown and tested on two series of Y zeolites modified by either steaming or pseudomorphic treatment, and the results are compared with previous attempts of fractal analysis. Zeolites steamed in the presence of NaCl were amorphized and deconstructed at the micro-mesopore level, with the calculated surface fractal dimension decreasing accordingly. Zeolites treated in alkaline media and in the presence of a pore directing template developed ordered mesoporosity. The fractal dimension increased for the last group, reaching values near 3. The refined method is shown to fit more reasonably the data of capillary condensation than either NK or volume-corrected algorithms, and gives surface fractal dimension values within the expected interval of 2–3. The surface fractal dimension is shown to function as a quantitative indicator of modifications on materials porosity, and it is implied that modern methods of isotherm interpretation are necessary and still expecting implementation to attain a better description of materials porosity.
Databáze: OpenAIRE
Externí odkaz: