Improvement of the hydrothermal stability of SAPO-34

Abstract

Hydrothermal stability of SAPO-34 is greatly improved by the treatment of the acidic form of the SAPO-34 with NH3.

Conversion of methanol to olefins: Stabilization of nanosized SAPO-34 by hydrothermal treatment

“…This behavior was already reported in the literature for more conventional SAPO-34 samples [22][23][24][25]. Briend et al [22] related the lack of long-term stability to the presence of silicon islands, favored by the use of morpholine as template.…”

“…Briend et al [22] related the lack of long-term stability to the presence of silicon islands, favored by the use of morpholine as template. Other authors [23,26] showed that the structural deterioration can be prevented if after removing the template the acid sites are covered with ammonia.…”

Improvement of low-temperature hydrothermal stability of Cu/SAPO-34 catalysts by Cu 2+ species

“…In addition, Janssen et al [8] proposed methods to inhibit the skeleton collapse of SAPO molecular sieve by using templates and carbonaceous material to shield the catalytic sites from contacting with H 2 O molecules. Mees et al [9] found that the hydrothermal stability of SAPO-34 was greatly improved by replacing the hydroxyl groups by amino species. These modification methods may be applied for the process of methanol to olefins (MTO); however, they are not practical for Cu/SAPO-34 catalysts during SCR process as hydrothermal exposure cannot be avoided in vehicle exhaust.…”

A novel one-pot synthesized CuCe-SAPO-34 catalyst with high NH3-SCR activity and H2O resistance

“…For used Cu-SAPO-34, the intensity of all diffraction peaks decreased significantly. The XRD patterns showed that the crystalline structure was changed by the action of H 2 O [11,19]. However, there was no evident decline of crystallinity for the used CuCe 0.06 -SAPO-34 sample compared to the fresh one.…”

“…This indicated that Ce ions may replace the proton of the Si\ \O(H)\ \Al bond to decrease the concentration of Si\ \O(H)\ \Al bonds, preventing the hydrolysis reactions at the acid sites [11,20]. The interaction of H 2 O with other framework atoms appeared to be much weaker and was reversible, improving the stability of the zeolite [19]. The higher stability of the CHA structure in CuCe 0.06 -SAPO-34 contributed to its higher water resistance in comparison with Cu-SAPO-34.…”