Economical Way to Synthesize SSZ-13 with Abundant Ion-Exchanged Cu⁺ for an Extraordinary Performance in Selective Catalytic Reduction (SCR) of NO_x by Ammonia

Abstract

In this study, an economical way for SSZ-13 preparation with the essentially cheap choline chloride as template has been attempted. The as-synthesized SSZ-13 zeolite after ion exchange by copper nitrate solution exhibited a superior SCR performance (over 95% NOx conversion across a broad range from 150 to 400 °C) to the traditional zeolite-based catalysts of Cu-Beta and Cu-ZSM-5. Furthermore, the opportune size of pore opening (∼3.8 Å) made Cu-SSZ-13 exhibiting the best selectivity to N2 as well as satisfactory tolerance toward SO2 and C3H6 poisonings. The characterization (XRD, XPS, XRF, and H2-TPR) of samples confirmed that Cu-SSZ-13 possessed the most abundant Cu cations among three investigated Cu-zeolites; furthermore, either on the surface or in the bulk the ratio of Cu(+)/Cu(2+) ions for Cu-SSZ-13 is also the highest. New finding was announced that CHA-type topology is in favor of the formation of copper cations, especially generating much more Cu(+) ions than the others, rather than CuO. The activity test of Cu(CuCl)-ZSM-5 (prepared by a solid-state ion-exchange method) clearly indicated that Cu(+) ions could make a major contribution to the low-temperature deNOx activity. The activity of protonic zeolites (H-SSZ-13, H-Beta, H-ZSM-5) revealed the topology effect on SCR performances.

Rational Synthesis of Chabazite (CHA) Zeolites with Controlled Si/Al Ratio and Their CO2/CH4/N2 Adsorptive Separation Performances

“…Therefore, severale fforts have been devotedt o preparing CHA zeolite by using alternative OSDAs. [41,42] In this contribution, we have synthesized CHA zeolites with different framework Si/Al ratios. The amount of TMAdaOH neededt o direct the crystallization of CHA zeolite with different Si/Al ratios wasi nvestigated systematically.T ot he best of our knowledge,t his is the first reporte lucidating the necessary amount of TMAdaOH to direct the formation of CHA zeolites with different framework compositions.…”

Template‐Free Synthesis of Hierarchical SSZ‐13 Microspheres with High MTO Catalytic Activity

“…However, the use of TMAdaOH has obvious disadvantages, such as relatively high cost of organic templates, and hazardous wastes formed during the thermal decomposition of organic templates normally carried out at high temperature. An economical way for synthesis with the less‐expensive choline chloride as template was reported . Nevertheless, this method can hardly eliminate the formation of harmful gases due to the combustion of the organic component.…”

Conversion of Y into SSZ-13 zeolites and ethylene-to-propylene reactions over the obtained SSZ-13 zeolites

“…SSZ-13 zeolites have been synthesized via various methods, including direct synthesis (from precursors of silica and alumina) and conversion of zeolite Y. For the synthesis of SSZ-13s, various templates, such as N,N,Ntrimethyl-1-adamantanamine iodide (TMAda-I) [5,7], TMAda-OH [8][9][10][11][12], choline chloride [13,14], copper-tetraethylenepentamine (Cu-TEPA) [15][16][17], tetraethylammonium hydroxide (TEA-OH) [18], benzyltrimethylammonium hydroxide [19], and N,N,Ndimethylethylcyclohexylammonium bromide [20] have been used despite several reports of its template-free [21][22][23][24] synthesis.…”