Synthesis and Modification of SAPO-34 Nanoparticles by Incorporation of Metal Ions Using Rapid High Temperature Method

Abstract

Considering studies done on the result of methanol conversion over SAP-34 molecular sieve, it is understood that increase of selectivity is ascribed to the increase of acidity in acid sites which is a result of incorporation of metal in crystal structure and decrease of crystal size. In this study, metal incorporation in the SAPO-34 structure leaded to increase of acid sites concentration but did not affect the acid strength distribution. The catalytic performance of the SAPO-34 nanoparticles in the MTO reaction varied according to their crystallite size. Decreasing particle size results in larger increase of external surface area and shorter diffusion path, both cause reduction in mass and heat transfer resistances in catalysis and sorption. In this work a rapid high-temperature synthesis method was developed to synthesis uniform nanoparticles of SAPO 34 zeolite with high crystallinity and metal was successfully incorporated in crystal structure. In order to investigate the effects of temperature and synthesis time on purity and crystallinity of the synthesized samples, the crystallization temperature was increased from 350 to 550 K while the synthesis time was decreased from 24 h to 45 min. The samples were characterized by XRD, BET and SEM analysis techniques. It was found that by using high temperature and short synthesis time the particle size decreased and the metal was properly incorporated into the crystal structure.

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

“…This procedure results in greater external surface area and shorter diffusion path. Therefore synthesized samples by this process show higher mass and heat transfer rates in catalytic and sorption applications [66]. Effective parameters in this method are aging time, crystallization time and temperature, template and water content in synthesis mixture Table 7 SDA composition of the initial gels [57].…”

Performance improvement of nano-sized SAPO-34 molecular sieves synthesised by different combinations of multi templates in MTO reaction

“…Therefore, many reports suggest that the effectiveness of SAPO-34 can be improved by www.prkm.co.uk reducing the crystal size [11,[14][15][16][17][18][19] because the crystal size specifies the residence time of DME in the crystal, and therefore the degree of methanol conversion [1]. Recently, different methods such as microwave irradiation [11,20], ultrasonic-assisted hydrothermal synthesis [13,21,22], dry gel conversion method [23], and the incorporation of metal ions into the SAPO-34 structure using a rapid high temperature method [24], have been employed to improve the properties of SAPO-34 [25]. In addition to the above methods, applying mixed templates [9,15,26] can enhance SAPO-34 catalytic performance by affecting the structure, morphology and particle size of the SAPO-34 crystals resulting in higher selectivity for olefins and longer lifetime [15,26,27].…”