Synthesis, characterization and catalytic properties of SAPO-34 synthesized using diethylamine as a template

Synthesis and characterization of DNL-6, a new silicoaluminophosphate molecular sieve with the RHO framework

“…In the case of no CTAB addition to the gel, it could be seen from Table 1 (C1) that only small amount of RHO was observed, coexisting with the main product of CHA phase. This is partly consistent with our previous research, in which CHA was the only product [27]. Addition of small amount of CTAB (C2, 0.05 mol) to the gel led to a product mainly in RHO phase.…”

“…N 2 adsorption measurement was carried out on a Micromeritics 2010 analyzer at 77.35 K after the sample was degassed at 350°C under vacuum. MAS NMR measurements were conducted on a Varian Infinity plus 400 WB spectrometer, where resonance frequencies were 79.41, 104.17, 161.83 and 100.5 MHz for 29 Si, 27 Al, 31 P and 13 C, respectively. Spinning rates of the samples at the magic angle were 4, 10, 6 and 8 kHz for 29 Si, 27 Al, 31 P and 13 C, respectively.…”

“…MAS NMR measurements were conducted on a Varian Infinity plus 400 WB spectrometer, where resonance frequencies were 79.41, 104.17, 161.83 and 100.5 MHz for 29 Si, 27 Al, 31 P and 13 C, respectively. Spinning rates of the samples at the magic angle were 4, 10, 6 and 8 kHz for 29 Si, 27 Al, 31 P and 13 C, respectively. Reference materials for the chemical shift (in ppm) determination were 2,2-dimethyl-2-silapentane-5-sulfonate sodium salt (DSS) for 29 Si and 13 C, 1.0 M AlðH 2 OÞ 3þ 6 for 27 Al and 85% H 3 PO 4 for 31 P. Thermal analysis was carried out on a TA Q600 analyzer at a heating rate of 10°C/min under an airflow rate of 100 ml/min.…”

“…Considering the high Si content in the sample (Si 0.135 Al 0.496 P 0.369 O 2 ), it is suggested that the framework of DNL-6 can accommodate high amount of single Si environment, close to the theoretical maximum [30]. Two resonance peaks existed in the 27 Al MAS NMR spectrum of as-synthesized DNL-6. One was at 8.2 ppm corresponding to tetrahedrally coordinated Al environment; another peak centered at 9.1 ppm should be ascribed to penta-coordinated Al environment, arising from additional interaction of water or template molecule to the framework alumina [31].…”

“…Based on the topological structure of DNL-6 molecular sieve, i.e., each unit cell (two cages) containing 48 T sites, the number of removable molecules per cage were calculated to be 4.28 DEA and 5.00 H 2 O. The template number in each cage of DNL-6 was obviously higher than that of SAPO-34-DEA (1.74) [27], in accordance with the larger cage in the RHO framework.…”