Characteristics of zeolite formation, such as being kinetically slow and thermodynamically metastable, are the main bottlenecks that obstruct a fast zeolite synthesis. We present an ultrafast route, the first of its kind, to synthesize high-silica zeolite SSZ-13 in 10 min, instead of the several days usually required. Fast heating in a tubular reactor helps avoid thermal lag, and the synergistic effect of addition of a SSZ-13 seed, choice of the proper aluminum source, and employment of high temperature prompted the crystallization. Thanks to the ultra-short period of synthesis, we established a continuous-flow preparation of SSZ-13. The fast-synthesized SSZ-13, after copper-ion exchange, exhibits outstanding performance in the ammonia selective catalytic reduction (NH3 -SCR) of nitrogen oxides (NOx ), showing it to be a superior catalyst for NOx removal. Our results indicate that the formation of high-silica zeolites can be extremely fast if bottlenecks are effectively widened.

The key reactive sites in the selective catalytic reduction (SCR) of NO using ammonia (NH3–SCR) are the Cu­(II)/Cu­(I) ammine complexes encapsulated within zeolite catalysts. The reaction intermediate in the important CuI → CuII reoxidation step has been proposed as the dicopper species. However, obtaining the definitive spectroscopic probe for the dicopper intermediate under NH3–SCR remains a quite challenging subject. Here we report spectroscopic evidence of the efficient generation of the dicopper intermediate in NH3–SCR over Cu-ion-exchanged zeolites. The state of the Cu ion under the NH3–SCR condition was analyzed using fiber-optic UV–vis–NIR spectroscopy; a distinct spectroscopic fingerprint of the (μ–η2:η2-peroxo)­dicopper­(II) intermediate was detected. Our spectroscopic assignment was rationalized by density functional theory calculations. The intensity of the spectroscopic fingerprints of dimeric copper was much higher than expected from previous reports, and it was also found that such a spectroscopic probe is observable only under the NH3–SCR conditions. This finding strongly supports the previously suggested Cu dynamic contributions to NH3–SCR catalysis.

Characteristics of zeolite formation, such as being kinetically slowa nd thermodynamically metastable,a re the main bottlenecks that obstruct af ast zeolite synthesis.W e present an ultrafast route,t he first of its kind, to synthesize high-silica zeoliteSSZ-13 in 10 min, instead of the several days usually required. Fast heating in atubular reactor helps avoid thermal lag, and the synergistic effect of addition of aS SZ-13 seed, choice of the proper aluminum source,and employment of high temperature prompted the crystallization. Thanks to the ultra-short period of synthesis,weestablished acontinuousflowpreparation of SSZ-13. The fast-synthesized SSZ-13, after copper-ion exchange,e xhibits outstanding performance in the ammonia selective catalytic reduction (NH 3 -SCR) of nitrogen oxides (NO x ), showing it to be as uperior catalyst for NO x removal. Our results indicate that the formation of high-silica zeolites can be extremely fast if bottlenecks are effectively widened.

We herein present a top-down methodology to prepare nanosized zeolites with tunable size by combining post-synthesis milling and fast recrystallization of several minutes (10 min for SSZ-13 and 5 min for AlPO4-5). A continuous-flow recrystallization process is demonstrated to further enhance the overall product efficiency.