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

Synthesis of SAPO-34 Molecular Sieves via Novel Intermittent Hydrothermal Treatment and Its Effect on the Crystallization and Product Properties

“…It can be seen that all the samples are in agreement with that of the CHA-structure SAPO-34 (PDF 47-0617) [2]. However, a little impurity can be seen in the S(4) and S (8) samples (peaks at 2θ = 7.4 • and 22.4 • ), which may be the aluminum phosphate carbon hydrogen nitride (PDF 89-8244), SAPO-5 (PDF 49-0659) or their mixture [22,23]. Because of the same space group and the low concentration, it is difficult to distinguish between them in the XRD patterns.…”

“…The possible reason is that very few crystal nuclei are produced at the beginning of the crystallization. The particle aggregation and growth take place rapidly after nucleation [22] because of the high concentration of material and the fast mass transfer rate. Thus, a few large crystals with some defects preliminarily appear, which are easily shattered and dissolved.…”

Investigation of synthesis time and type of seed along with reduction of template consumption in the preparation of SAPO-34 catalyst and its performance in the MTO reaction

“…[5][6][7][8] Up to now, among all catalysts, SAPO-34 zeolite with a chabazite (CHA) framework has shown the best prociency in the MTO process because of its high shape selectivity, small pore size (0.38 nm), mild acidity, large accessible surface area, and hydrothermal stability. [9][10][11] The preparation of pure SAPO-34 is important both in terms of the characterization and the application points of view. According to the synthesis conditions, SAPO-34 with the CHA structure competes with SAPO-5 phase (AFI structure), as the CHA structure increases with increasing the template amount.…”

Three‐Stage Crystallization: an Effective Way to Reduce the Crystal Size and Improve the Catalytic Performance of SAPO‐34 for MTO

“…Triethylamine and morpholine (MOR) are much cheaper than TEAOH. However, gels with them as template have higher crystal growth speed than ones with TEAOH do, which leads to the formation of large scale SAPO‐34 crystal . In order to overcome the rapid crystal growth and increase the amount of initial crystalline grain, we lower the crystallization temperature after short high temperature duration, then raise the crystallization temperature again for the further nucleation and crystal growth.…”