Abstract
The hydrothermal synthesis of aluminophosphate molecular sieve type AlPO4-11 was processed from chemicals containing psueudobohemite, 85% phosphoric acid, water, and di-isopropylamine as templating agent. The crystallization of the samples was studied by taking samples in times from 2 to 74 h. The obtained white powder products were characterized by X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG) and differential scanning calorimetry (DTG) data and pH measurement of the mother liquor. The pore volume, as determined from TG and DTG curves, was ca. 0.17 cm3g−1. The percent relative crystallinity was determined by XRD and FT-IR methods. The crystallization kinetics evidenced that the hydrothermal synthesis of AlPO4-11 exhibited in its initial phase a behavior of first order reaction with a specific velocity constant of ca. 0.25 h−1, as determined from XRD and FT-IR data. The results obtained by both X-ray diffraction and infrared spectroscopy are comparable, and FT-IR is found to be a rapid method for estimating crystallinity and structure of aluminophosphate.
Highlights
One of the most important materials in the chemical and petrochemical industry are molecular sieves, as they have open structures containing pores and cavities. These materials generally known as zeolites, aluminophosphates and silicoaluminophosphates are widely used as adsorbents, catalysts and ion exchangers in addition to applications in nanotechnology, in the area of optical sensors, due to their electronic properties [1]
The aluminophosphate molecular sieves represent a class of microporous materials free of silica, first reported in 1982 by Wilson et al [2], which are synthesized by the hydrothermal method
The synthesis procedure consists of a modified process described elsewhere [19,20], in relation to the order or mixing the reactants, summarized as follows: (i) pseudoboehmite was slurried in half of total volume of water required at synthesis; (ii) the phosphoric acid was diluted with the volume of remaining water; (iii) the phosphoric acid solution was added to the suspension obtained in step (i) and (iv) addition of DIPA to the mixture
Summary
One of the most important materials in the chemical and petrochemical industry are molecular sieves, as they have open structures containing pores and cavities. The aluminophosphate molecular sieves represent a class of microporous materials free of silica, first reported in 1982 by Wilson et al [2], which are synthesized by the hydrothermal method. These solids are denoted as AlPO4 -n, where “n” is an indicative number of the structure type. After the discovery of aluminophosphates, various related materials have been synthesized [3,4,5,6]
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