Synthesis of Chabazite Zeolite via Faujasite Conversion Using 1-(1-Methylpropyl)-4-aza-1-azoniabicyclo[2.2.2]octane Hydroxide as Cost-Effective Structure-Directing Agent

Graphical Mono-quaternary 1-(1-methylpropyl)-4-aza-1-azoniabicyclo[2.2.2]octane hydroxide is proposed to direct the Faujasite-to-Chabazite inter-zeolite conversion to generate 35–258 nm CHA crystals with Si/Al ratio of 7.2. The Cu-CHA zeolite exhibits superior hydrothermal stability and catalytic performance in standard NH 3 -SCR process. Cu-exchanged chabazite zeolite is the state-of-the-art used on-board catalyst for NO x selective reduction by ammonium (NH 3 -SCR), and the zeolite is currently generated in the presence of N , N , N -trimethyl-1-adamantylammonium hydroxide, serving as organic structure-directing agent (OSDA). The expensiveness of this OSDA increases the catalyst production cost, while its low degradability brings about environmental concerns in post treatment of waste water. Here, a new type OSDA, 1-(1-methylpropyl)-4-aza-1-azoniabicyclo[2.2.2]octane hydroxide, is proposed to direct Faujasite-to-Chabazite inter-zeolite conversion and generate chabazite with Si/Al ratio up to 7.2. The obtained zeolite possesses high hydrothermal stability for the high crystallinity, siliceous framework and low concentrations of Si(2Si, 2Al) sites. The Cu-form catalyst exhibits better catalytic performance in standard NH 3 -SCR process for the tiny crystallite size (35–258 nm) and formation of highly dispersed copper sites. The synthesis offers a new type of OSDA to fabricate zeolites and expands the toolkit to regulate their physicochemical properties.