Effect of alkaline metal on microporosity of acidic alkaline salts of 12-tungstophosphoric acid

✍ Scribed by Miki Yoshimune; Yusuke Yoshinaga; Toshio Okuhara

• Book ID: 104430619
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 226 KB
• Volume: 51
• Category: Article
• ISSN: 1387-1811
• DOI: 10.1016/s1387-1811(01)00480-2

✦ Synopsis

A series of M 2:1 H 0:9 PW 12 O 40 (M ¼ Cs, Rb, and K) was synthesized and their pore structure was characterized. The pore-width was evaluated by adsorption of various molecules with different size. The micropore and the mesopore sizedistributions were systematically analyzed with Ar and N 2 adsorption-desorption isotherms, respectively. It was found that the pore-width of M 2:1 H 0:9 PW 12 O 40 increased as the cation size of alkali metal decreased. It should be emphasized that Rb 2:1 H 0:9 PW 12 O 40 as well as Cs 2:1 H 0:9 PW 12 O 40 possesses uniform ultramicropores, while the pore-width of K 2:1 H 0:9 PW 12 O 40 distributed widely. It is further worthy to note that the pore-width of Rb 2:1 H 0:9 PW 12 O 40 was estimated to about 0.60 nm and the external surface area was only 3% that of the total surface area. These results demonstrate that Rb 2:1 H 0:9 PW 12 O 40 is a novel ultramicroporous material having the pore-width similar to that of H-ZSM-5.