| 摘要 |
<p>A composition comprises a synthetic zeolite having a CHA framework structure, a molar silica-to-alumina ratio SAR of 25 to 150, and an in-situ transition metal uniformly dispersed within the cavities and channels of the zeolite. The transition metal may be copper or iron. A further composition comprises synthetic zeolite containing copper, having a CHA framework structure, and a unit cell volume of 2355 to 2375 Ã
3. A further composition comprises a synthetic zeolite having a CHA framework structure, 0.1 to 5 weight percent of non-framework copper, a phase purity of at least 95% by weight, and less than 5 weight percent CuO. A method for synthesizing a zeolite comprises: preparing a mixture comprising (a) at least one source of alumina, (b) at least one source of silica, (c) a transition-metal-amine organic templating agent, (d) seed crystals, and (e) a distinct second organic templating agent, each of the templating agents being suitable for forming a CHA structure, the reaction mixture being essentially free of fluorine; heating the reaction mixture to form zeolite crystals having a CHA framework SAR of at least 25 and containing the transition metal.</p> |
