Synthesis Of NaY Zeolite Without Structure-Directing Agent

NaY Zeolite has been widely used on catalysis, adsorption and ion exchange, duing to its special structure and property. Recently, people found the small sized NaY zeolite has not only a large surface area but also big surface energy. That is why small sized NaY zeolite has higher catalytic efficiency and lower energy expensive which are better for the idustrial process.Usually NaY zeolite is hydrothermally synthesized with structure-directing agent. Though NaY zeolite made by this mathod has good quality, small size and high productivity, it also has some shortages:it cost too many time and raw materials, because the structure-directing agent needs to be perparted and it has some useful time. In this paper, Si-Al gel is aged for some time at room temperature in order to make a lot of crystal nuclears. Those nuclears will be the seed crystal in the hydrothermal synthesis. By using Si-Al gel, about 400nm sized NaY zeolite with good quality has been hydrothermally synthesized very fast (about 4 hours).In this paper, the influence of alkalinity, crystallization time and aging time on the synthesis of NaY zeolite is been discussed. According to the characterization of XRD, SEM, Mastersizer and so on, we can summarize:Si-Al gel with about 9.0 Na2O/SiO2 and 22 H2O/Na2O is aged for 24 hours at room temperature, then can been transform into NaY zeolite after 12 hours crystallization at 100℃. This NaY zeolite is pure, small and good quality.In this paper, the influence of alkalinity, crystallization time and aging time on the particle size of NaY zeolite is also been discussed. According to the particle size distribution of products, we can summarize:In a range of alkalinity NaY zeolite with shorter crystallization time and langer aging time will be smaller size.Besides, the characterization of TG and DTA demonstrates the thermostability of products is good. And they can be used on the industrial process.