Enhancement on the hydrothermal stability of ZSM-5 zeolites by the cooperation effect of exchanged lanthanum and phosphoric species

✍ Scribed by Gang Yang; Jianqin Zhuang; Yan Wang; Danhong Zhou; Maoqing Yang; Xianchun Liu; Xiuwen Han; Xinhe Bao

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 381 KB
• Volume: 737
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2004.11.018

✦ Synopsis

It was explored by density functional calculations that exchanged La or P species exert great influence on the local Al sites as well as on the adjacent exchanged species. In partially exchanged La-or P/H-ZSM-5 zeolite, some of the Al sites will fall off from the zeolite framework even more easily than in H-form ZSM-5, consistent with our XRF experiments. However, when exchanged by both La and P species, Al at either of the two exchanged sites shows better stability compared to H-from zeolite. La and P species will interact strongly with each other, as evidenced by the charge donation process and the shortening of P-O 1 bond length. It was just the cooperation of La and P species that enabled RSCC catalysts worked normally under severe conditions.