Facile synthesis of SAPO-34 with small crystal size for conversion of methanol to olefins

Abstract

a b s t r a c t a r t i c l e i n f oSAPO-34 molecular sieves were fabricated by a dry gel liquid-phase transport method using morpholine (Mor) or morpholine-tetraethylammonium hydroxide (Mor-TEAOH) as the structure-directing agent (SDA). The prepared samples were characterized by scanning electron microscope (SEM), nitrogen adsorption-desorption, X-ray diffraction (XRD), ammonia temperature-programmed desorption (NH 3 -TPD), thermo-gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR). The results indicated that the dry gel liquid-phase transport method is very effective to fabricate SAPO-34 molecular sieves with average crystal size about 0.6 μm using Mor-TEAOH as SDA and 3 μm using Mor as SDA, respectively. Moreover, the addition of TEAOH is beneficial to produce SAPO-34 with small crystal size. Methanol-to-olefins (MTO) reaction was chosen to test the catalytic performance of as-prepared SAPO-34 catalysts. The prepared SAPO-34 catalyst using Mor-TEAOH as SDA exhibited the excellent catalytic performance in MTO process owing to its small crystal size and high crystallinity. The conversion of methanol and selectivity of ethylene and propylene are up to 100% and 87.9%, respectively.

Performance of Methanol-to-Olefins Catalytic Reactions by the Addition of PEG in the Synthesis of SAPO-34

“…[28]. Framework vibrations can be observed at 490, 632, 730, 1095, 1651 and 3445 cm -1 , which are similar to those of the CHA structure [29]. The absorption peaks at 490 and 632 cm -1 are T-O bending bands of SiO 4 and D-6 rings, and the bands at 730 and 1095 cm -1 correspond to the symmetric stretch vibration of P-O and Al-O and asymmetric stretch vibration of O-P-O, respectively.…”

Synthesis of ultra-small mordenite zeolite nanoparticles

“…Due to the amount of aluminosilicate was constant, zeolites with small crystal size were generated. The particle size of the samples was decreased with increasing the concentration of TEAB in our synthesis system [18,19].…”

Metal–organic framework-assisted synthesis of Zr-modified SAPO-34 zeolites with hierarchical porous structure for the catalytic transformation of methanol to olefins

“…31 The high-temperature peak of β is attributed to the desorption of ammonia molecules from strong Brønsted and Lewis acid sites (mid-strong and strong acid sites). 32 It can be seen that the position of the low-temperature peak has no obvious change, but the position of the high-temperature peak gradually shifts to a higher temperature with increasing Zr load quantity. Zr introduced into SAPO-34 zeolites is conducive to enhance the strength of the acid sites at high temperature.…”