Synthesis Of Zeolite Beta In Present Of Seed Crystal

As a high-silica zeolite with a three-dimensional network of 12-ring pores structure, zeolite Beta has been widely used in petroleum processing and chemical industries. But in the process of synthesizing zeolite Beta, it is necessary to add large amount of expensive organic template to the initial gel. And it must be calcined at high tempreture to get the open micropores, this is not only time consuming and need great effort, but also the roasting causes environmental pollution. To some degree, it has limited the wide use in the industry. Therefore, synthesis of zeolite beta without any organic template becomes the issue.In this paper, we described synthesis of zeolite Beta in present of seed crystal without organic template, and discussed the influence of different seeds and synthesis conditions on the Si/Al of the synthetic products. At the same time, we get the optimum synthetic condition. In our synthesis system, three kinds of zeolite Beta seeds, which were synthesizd and calcined to remove template, were used. Results show that Si/Al of the products does not increase with the inreases of zeoltes Beta seeds'. And the much more or less Na₂O addition into the initial gel will result in smaller Si/Al of products. The Si/Al of proucts increases first and then decreases with increases of Na₂O/SiO₂ ratios in the Na+-aluminosilicate gel. We also found that using alkaline silica sol as starting material the Beta synthesized by static hydrothermal crystallization at 140 ? for 3 days has good crystallinity. When using acidic silica sol obtaine products with good relative crystallinity was hydrothermally synthesized at 120 ? for 2.5days? In spite of the crystaliization time and temperature reduces, the Si/Al of the Beta becomes smaller compared with that using alkaline silica sol.In the research, we chose the following conditions the Beta ?SiO₂/Al₂O₃= 23.68? as the seed, alkaline silica sol as the silica cource, the hydrothermal crystallization at 140 ? for 3 days to synthesized Beta with molar composition xNa₂O:yH₂O:zSiO₂:Al₂O₃, where x= 11.6, y=800, z=40, and the product had the better relative crystallinity, uniform particle size distribution, and the larger silicon-aluminum ratio ?SiO₂:AlO₃=12.68?.