Qian Yi,Jiang Qingqing,Xiang Shimeng,Lu Zhenhao,Xu Xiaowen,Yang Jing,Dai Guoliang,Song Ruifeng,Jiang Ji
Separating CO 2 and N 2 from CH 4 is crucial for energy production and environmental protection. This study showed the rapid synthesis of CHA zeolites with different morphologies using an in situ growth method, without the assistance of organic structure directing agents (OSDA) or fluoride media. The crystallization behavior of CHA zeolites was studied in terms of synthesis gel composition (including water content, silicon and aluminum content, alkalinity and Sr 2+ concentration), synthesis temperature and duration. The results suggested that pure phase CHA zeolite nano-aggregates could be synthesized with broad precursor conditions at 150 °C for only 4 h. Then, K-CHA zeolite was ion-exchanged to Na-CHA and Ca-CHA and the adsorption properties of CHA zeolites with different morphologies and ions were studied. The results suggested that Na-CHA exhibited highest CH 4 , CO 2 and N 2 adsorption capacity and showed higher ideal selectivity for N 2 /H 2 ; Although Ca-CHA zeolites exhibited relative lower CO 2 and CH 4 adsorption capacity, it exhibited the highest ideal selectivity for CO 2 /CH 4 ; Simultaneously, K-CHA zeolite exhibited high CH 4 adsorption capacity and high adsorption separation ability of CH 4 /N 2 . Furthermore, breakthrough experiments have confirmed the practical feasibility of separating CO 2 from CH 4 .
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.
危险品化学品经营许可证（带存储）