Synthesis of Titanosilicates and Related Materials

Synthesis and crystal structure of a new microporous silicate with a mixed octahedral-tetrahedral framework: Cs3ScSi8O19

“…For the REE 3+ ion which is smallest and most similar to Sc 3+ , i.e. Lu 3+ , three related compounds have been described: Na 5 LuSi 4 O 12 (Merinov et al, 1978;Filipenko et al, 1997) which is isotypic with the already mentioned Na 5 ScSi 4 O 12 , K 3 LuSi 2 O 7 (Vidican et al, 2003) which has a layered hexagonal structure based on isolated LuO 6 octahedra and interlinking Si 2 O 7 groups, and K 6 Lu 2 Si 6 O 18 (Filipenko et al, 1988) Rocha and Anderson, 2000;Anderson and Rocha, 2002), it is found that a relatively close structural relation exists with Cs 2 TiSi 6 O 15 (two very similar polymorphs with space groups C2/c and Cc are known: Grey et al, 1997;Nyman et al, 2000a). The crystal structure of the polymorph described by Grey et al (1997) is used here for the comparison: it contains isolated TiO 6 octahedra and SiO 4 tetrahedra (both quite regular), which share all corners to form an open framework structure containing large cavities hosting the Cs + ions.…”

Microporous Mixed Octahedral-Pentahedral-Tetrahedral Framework Silicates

“…Advances in the fi eld of OPT microporous materials have been reviewed by Rocha and Anderson (2000), Anderson and Rocha (2002) and Chukanov et al (2004). Because signifi cant progress has been made in the last three years, we believe it is now timely to appraise this recent work.…”

“…The studies on framework insertion of aluminum, gallium, boron, niobium, vanadium and chromium on ETS-10 and a few other materials have been reviewed (Rocha and Anderson 2000;Anderson and Rocha 2002).…”

“…For instance, Bortun et al (1997); Lin et al (1999a,b); and Jale et al (1999), extended the OPT fi eld to zirconosilicates, reporting the synthesis of a synthetic analogue of the mineral gaidonnayite (Na 2 ZrSi 3 O 9 ·2H 2 O). Until the end of the last century, many microporous OPT minerals containing other metals, such as Nb, V, Sn and Ca, have been reported (Rocha and Anderson 2000;Anderson and Rocha 2002). Following the synthesis and structural characterization work, the potential applications of these novel materials have been evaluated, particularly in the areas of catalysis, separation and ion-exchange.…”

“…Microporous structures comprised entirely of octahedral sites are also known, encompassing manganese oxides (OMS materials, Suib 1998) and phases with composition Na 2 Nb 2 x M x O 6 x (OH)x H 2 O, where M = Ti, Zr, and 0< x 0.4 (SOMS solids; Nyman et al 2001Nyman et al , 2002. Mixed octahedral-pentahedral-tetrahedral microporous (OPT) siliceous frameworks have been much studied since the early 1990s (Rocha and Anderson 2000;Anderson and Rocha 2002). Comprehensive research into synthetic OPT materials was initiated by the seminal contributions of Kuznicki (1989Kuznicki ( , 1990 (titanosilicates ETS-4 and ETS-10), Chapman (1990); Chapman and Roe (1990) , and titanosilicate analogues of minerals vinogradovite and pharmacosiderite) and Anderson et al (1994Anderson et al ( , 1995b) (ETS-10), and the early work of the groups of Raveau (Choisnet et al 1976(Choisnet et al , 1977 (tantalo and niobosilicates), and Corcoran et al ( , 1992 (stannosilicates).…”