Investigating the mixing sequence and the Si content in SAPO-34 synthesis for selective conversion of methanol to light olefins using morpholine &/ TEAOH templates

CATEGORY: METHANOL TO OLEFINS
Investigating the mixing sequence and the Si content in SAPO-34 synthesis for selective conversion of methanol to light olefins using morpholine &/ TEAOH templates

Type	Journal Article
Author	Mohammad Ghavipour
Author	Amin Soleimani Mehr
URL	Free Full Text Source:  http://pubs.rsc.org/en/content/articlelanding/2016/ra/c5ra23432h
Volume	6
Issue	21
Pages	17583-17594
Publication	RSC Advances
Date	2016/02/09
Abstract	SAPO-34, the commercialized catalyst of methanol to olefin (MTO) process, was synthesized by single and mixed-template methods using TEAOH and morpholine. Researchers examined differing mixing sequences of initial materials for gel preparation according to four distinct procedures. Researchers found that the sequence of mixing was of crucial importance in SAPO-34 synthesis and the optimum mixing sequence was strongly related to the type of template. The Si content in the gel composition was also varied (SiO2/Al2O3 = 0.1 to 0.6 or % Si/Si + Al + P = 2.4 to 13) and, interestingly, not just the strength and amount of acid sites but also the particle size and surface area of the resulting catalysts were dramatically changed from 0.6 μm and 691 m2 gcat−1 to 1.6 μm and 468 m2 gcat−1, respectively. The catalysts performances, life times and products distributions were also analyzed in MTO reaction by a fixed bed reactor at 400–430 °C. The SAPO-34 sample using TEAOH with SiO2/Al2O3 of 0.3 showed the best activity among single-template samples (light olefin selectivity of 78.9%). Mixed-template SAPO-34 samples were also prepared by two synthesis procedures and one of them showed a higher surface area (543 m2 g−1) and smaller particles (1.1 μm) than the single-template SAPO-34 with the same Si content. The longest catalyst life time with light olefin selectivity of 81.9% was recorded on this mixed-template SAPO-34 at 400 °C and WHSV = 1 gMeOH gcat−1 h−1.