Synthesis, characterization and crystallization mechanism of SAPOs from natural kaolinite

Performance of CuO–ZnO–ZrO2 and CuO–ZnO–MnO as metallic functions and SAPO-18 as acid function of the catalyst for the synthesis of DME co-feeding CO2

“…Furthermore, the specific surface area of SAPO-18 is significantly higher than that of the γ-Al 2 O 3 prepared in the laboratory (which is larger than that of the commercial γ-Al 2 O 3 ). Moreover, SAPO-18 also has a higher pore volume, partially attributed to the micropores of the crystalline channels and to the presence of mesopores (empty spaces between crystals) [57]. As a result of these differences in the properties of the individual metallic functions, the physical properties of the bifunctional catalysts are ordered as follows: BET surface area, CZZr/S ≈ CZMn/S N CZA/S; pore volume, CZMn/S N CZZr/S N CZA/S.…”

Synthesis of SAPO-34 from metakaolin: Crystallization mechanism of SAPO-34 and transformation processes of metakaolin

“…Zhu et al [15] prepared a hierarchically structured SAPO-34 with sphere-like shape using metakaolin and TEA. The synthesis of SAPO-5, SAPO-11, SAPO-20, SAPO-34, SAPO-44 and SAPO-47 with a high crystallinity and uniform morphology from metakaolin was also demonstrated in our previous work [16]. However, the influence of metakaolin content on synthesis, properties and Si coordination environments of SAPO-34 is not clear so far.…”

“…Yan et al [20] examined the crystallization processes in the presence of HF as well, but they assumed that dry powder transformation with the assistance of the water vapor from the intermediate probably took place. In our previous work [16], isolated Si environment in SAPO-34 lattice was found in the initial crystals, demonstrating that metakaolin dissolved and solution-mediated transport mechanism occurred. Nevertheless, Si content provided by metakaolin was high (2.00Al:1.00Si:2.00P) and some of Si atoms formed Si domains.…”

“…Materials were prepared according to the report of our previous work [16]. Typically, metakaolin was mixed with morpholine and deionized water to form slurry A. Pseudoboehmite and phosphoric acid were added into deionized water to form gel B.…”

“…However, only several researchers have reported synthesis of SAPOs [14][15][16] from kaolin, which is a cheap and abundant mineral and usually used to produce aluminosilicate zeolites in industries. Zhou et al [14] introduced calcined kaolin (i.e.…”