A Facile Synthesis of SAPO-34 Molecular Sieves with Microwave Irradiation in Wide Reaction Conditions

Abstract

Various reaction conditions including temperature, time and type and concentration of templates have been changed in order to facilely synthesize, especially with microwave (MW) heating, SAPO-34 molecular sieves. SAPO-34 molecular sieve can be synthesized rapidly with microwave irradiation from a gel containing tetraethylammonium hydroxide (TEAOH) as a template. However, other several templating molecules lead to SAPO-5 molecular sieve under microwave irradiation even though SAPO-34 is obtained by conventional electric synthesis from the same reactant gels. Moreover, SAPO-34 can be obtained more easily by increasing the TEAOH or silica concentration or by increasing the reaction temperature. SAPO-34 can be obtained within 5 min in a selected condition (high temperature of 210 o C) with microwave heating, which may lead to a continuous production of the important material. SAPO-34 synthesized by microwave irradiation is homogeneous and small in size and shows acidity and a stable performance in the dehydration of methanol and 2-butanol to olefins, suggesting potential applications in acid catalysis.

Different techniques and their effective parameters in nano SAPO-34 synthesis: A review

“…The first step of heating the gel usually happens so quickly in the microwave oven and also incorporation of soluble species occurs faster under the microwave irradiation due to more mobility and higher solubility of silicate species. As discussed by many researchers [84,[89][90][91][92][93][94][95][96], there are many contributing factors that affect the SAPO-34 properties such as microwave heating power and time, reaction temperature, aging and crystallization time, H 2 O and template content which will be discussed thoroughly.…”

Aluminium chloride: A new aluminium source to prepare SAPO-34 catalysts with enhanced stability in the MTO process

“…However, small SAPO-34 crystals with a uniform particle size have been obtained mainly through fractionation of the products. In this sense, nowadays several attempts to synthesize SAPO-34 and other zeolitic and mesoporous materials with small crystal size have been carried out using different approaches: synthesis from colloidal solutions [27,28] or applying microwave heating [28][29][30][31][32][33].…”

The seeded growth of dense and thin SAPO-34 membranes on porous α-Al2O3 substrates under microwave irradiation

“…By comparison, SAPO-34 crystals synthesized under microwave irradiation were more homogeneous in morphology and smaller in size [6,[11][12][13], while the synthesis time was seriously reduced [11,14]. Furthermore, the uniformly distributed crystals could be covered on porous substrates to form thinner SAPO-34 membranes when the microwave-assisted heating was applied [9,10].…”

“…SAPO-34 crystals and membranes could be synthesized by the hydrothermal crystallization method under either conventional electric heating [5][6][7][8] or microwave irradiation [6,[9][10][11][12][13][14]. By comparison, SAPO-34 crystals synthesized under microwave irradiation were more homogeneous in morphology and smaller in size [6,[11][12][13], while the synthesis time was seriously reduced [11,14].…”