Widening Synthesis Bottlenecks: Realization of Ultrafast and Continuous-Flow Synthesis of High-Silica Zeolite SSZ-13 for NOx Removal

Angew Chem Int Ed Engl. 2015 May 4;54(19):5683-7. doi: 10.1002/anie.201501160. Epub 2015 Mar 20.

Abstract

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.

Keywords: NOx removal; crystal growth; heterogeneous catalysis; seeded growth; zeolites.