Synthesis of hierarchical SAPO-34 to improve the catalytic performance of bifunctional catalysts for syngas-to-olefins reactions

Hydrogenation of CO2 into aromatics over ZnZrO–Zn/HZSM-5 composite catalysts derived from ZIF-8

“…Cheng et al 35 found that in an H 2 atmosphere, the carbon deposition during the conversion process of methanol over the HZSM-5 zeolite was less than that in the N 2 atmosphere. Identical results were found by Wang et al 44 Therefore, in the reaction system for directly preparing aromatics via CO 2 hydrogenation, the presence of H 2 can inhibit the formation of carbon deposits in the Zn/Z5 zeolite, which is one of the reasons why the ZnZr 8 O(350)-Zn/Z5 composite catalyst exhibits high stability. In the composite catalyst systems, the migration of metal species to the zeolite is driven by high temperature, a reductive atmosphere, and the formation of water vapor, and will cause irreversible deactivation of the catalyst.…”

Metal–organic framework-assisted synthesis of Zr-modified SAPO-34 zeolites with hierarchical porous structure for the catalytic transformation of methanol to olefins

“…10 However, the Zr 0.25 -SAPO-34, Zr 0.50 -SAPO-34 and Zr 0.75 -SAPO-34 zeolites exhibit typical type IV isotherms with H 4 type hysteresis loops in the scope of 0.45 < P/P O < 0.90, illuminating that mesoporous structures exist in the Zr-modified SAPO-34 zeolites. 29 Also, compared with the isotherm of the conventional SAPO-34 zeolites, more obvious uptake is observed at nearly saturation pressure in the isotherms of the Zr 0.25 -SAPO-34, Zr 0.50 -SAPO-34 and Zr 0.75 -SAPO-34 zeolites, indicating the coexistence of macropores in these three zeolites. 13 The above results are in accordance with the SEM and TEM characterization.…”

On the reaction mechanism of MnOx/SAPO-34 bifunctional catalysts for the conversion of syngas to light olefins

“…Interestingly, an optimal O/P ratio of 7 was obtained for 5% of SAPO-34 suggesting that, as the hydrogenation properties of MnOx, the acidity of the zeotype plays a significant role in the consecutive hydrogenation of olefins. 13,21,27 The evolution of in situ DRIFT spectra recorded over time at -2 °C under 20 mL.min -1 of 2.5%CO-He flow is plotted in Fig. 2: the bands corresponding to Mnx(CO)y species were observed immediately and they increased for the first 12 min before being strongly decreased afterwards.…”

“…[28][29][30][31] Alternatively, MnOx, 32 MnGaOx, 33,34 or ZrInOx, 35 was used. The zeotype corresponded most of the time to microsized) or to mesoporous M-SAPO, 8,11,32 hierarchical SAPO-34, 21 nanosized SAPO-34, 12,25 SAPO-18, 13,18 SAPO-35, 18 various SAPOs, 24 AlPO-18, 36 SSZ-13, 17,20 . Finally, note that a 1000 t.y -1 industrial pilot plant was built in Shaanxi, China.…”

“…7,9 It is designed in the literature either by OXZEO or more generally by STO (syngas to olefins). Most of oxides contained Zn: ZnO, 11 ZnCrOx, 8,[12][13][14][15][16][17][18][19] ZnZrOx, 10,20,21 ZnAlOx, [22][23][24] Zrpromoted ZnAlOx, 25 La-doped ZnAlOx, 26 Zn spinels, 27 ZnCeZrOx. [28][29][30][31] Alternatively, MnOx, 32 MnGaOx, 33,34 or ZrInOx, 35 was used.…”