Synthesis of Gallosilicate Type Molecular Sieve with CDO Topology and Application to Solid Acid Catalyst

Abstract

The gallosilicate type CDS-1 zeolite ([Ga]CDS-1) with CDO topology is prepared from the precursor of galliumcontaining layered material ([Ga]PLS-1) by calcination via dehydrative condensation, and the corresponding [Ga] PLS-1 can be successfully synthesized from the mixture of protonated kanemite (H-kanemite), Ga2O3, tetramethylammonium hydroxide (TMAOH) as structure-directing agent (SDA), NaOH and H2O. These materials have been characterized by powder XRD, TG-DTA, FE-SEM, nitrogen adsorption and solid state NMR, and their solid acid properties were evaluated by NH3-TPD analysis after protonation. The obtained proton type [Ga]CDS-1 zeolite can be applied for catalytic cracking reactions (1-hexene and ethylbenzene) and methanol-to-olefin (MTO) reaction as a novel solid acid catalyst.

Synthesis of germanosilicate type CDS-1 zeolite with CDO topology and its zeolitic layered precursor

“…were observed at 3.3 ppm for 1 H and 57 ppm for 13 C, respectively. Those are well agreement with our recent reported chemical shifts of metallosilicates PLS-1 [28,29]. Other samples of [Ge]PLS-1 are also same spectra charts (Figure not shown).…”

“…The 29 Si CP/MAS NMR spectra of the layered precursor [Ge]PLS-1 are also given in Fig. 7, in which broad three peaks being assignable as Q 3 and Q 4 silicon were clearly observable.…”

“…Surface areas and pore size distributions of the obtained samples were estimated by BET and HK methods using their isotherms. Solid-state 1 H and 29 Si magic angle spinning (MAS) NMR spectra and 13 C cross polarization (CP) MAS NMR were recorded at ambient temperature by using 4 mm diameter zirconia rotor with a spinning rate of 6 kHz (ECA-500 NMR spectrometer, JEOL Ltd.). Thermal gravitational (TGA) and differential thermal (DTA) analyses were carried out by using a Shimadzu DTG-50 analyzer at a ramping rate of 10 K/min under an air stream.…”

“…These results indicate that the treatment at 500°C for 6 h of [Ge]PLS-1 is suitable conditions to give the [Ge]CDS-1 zeolite with reasonable microporosity. Figure 11 shows the solid state 29 Si MAS NMR charts of [Ge]CDS-1 zeolites with different SiO 2 /GeO 2 ratio. The broad peak at around -110 ppm corresponding to Q 4 Fig.…”

“…Among these materials, the PREFER (layered precursor of ferrierite) has been interestingly investigated [13][14][15][16][17], in particular, the delaminated PRE-FER (ITQ-6) [18,19] has applied for catalysts and novel supports as a nano-sheet silicate [20][21][22][23][24][25]. We have reported the synthesis of boron-containing [B]PLS-1 and [B]CDS-1 zeolite by dry gel conversion (DGC) method using layered silicate H-LDS which is structural resemblance of layered silicate kanemite [26][27][28], and recently reported the [Ga]PLS-1 and [Ga]CDS-1 zeolite applying on the methanol-to olefin (MTO) reaction as a solid acid catalyst [29]. However, up to date, there are not much report for the synthesis of microporous metallosilicates with CDO topology [30,31].…”