MTO reaction over SAPO-34 catalysts synthesized by combination of TEAOH and morpholine templates and different silica sources

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

“…These outcomes are identical with the obtained results from Salmasi et al's experiment [40]. They verified the above mentioned results with synthesizing three samples with different TEAOH: morpholine ratios (1.5:0.5, 1:1, 0.5:1.5).…”

“…Normal silica sources that are used for SAPO-34 synthesis are TEOS, fumed silica, colloidal silica and silicic acid [35,40]. Several researchers have demonstrated that silica source has a strong effect on crystallinity, crystal size and morphology of zeolite particles due to their different solubility in the alkaline medium [41].…”

“…To observe the effect of colloidal silica and silicic acid, Salmasi et al [40] compared two samples with the same synthesis condition. Crystallinity of SAPO-34 crystals is decreased by using silicic acid and colloidal silica leads to smaller crystal size.…”

“…These results confirm previous observations for different reactivity and solubility of various silica sources which lead to different product characteristics. In fact the high surface area of colloidal silica, make it to dissolved more easily at a basic medium in comparison with silicic acid [40,42,43].…”

Synthesis of SAPO-34 using metakaolin in the presence of β-cyclodextrin

“…The weak acid sites originate from P-OH groups not fully linked to AlO 4 tetrahedron and the hydroxyl groups (-OH) bounded to the defect sites [20]. The strong acid sites are assigned to the incorporation of Si into the framework of SAPO-34 and have decisive influence on the performance of SAPO-34 samples for MTO process [21]. As the content of β-CD increased, the amount of weak acid sites increased apparently which can be attributed to the increased defects in the crystals.…”