AlPOs/SAPOs

Thirteen stmctures of various compositions, as AlPO SAPO, MeAPO, and MeAPSO, are available from UOP. 

There is no systematic nomenclature developed for molecular sieve materials. The discoverer of a synthehc species based on a characteristic X-ray powder diffraction pattern and chemical composihon typicaUy assigns trivial symbols. The early syn-thehc materials discovered by Milton, Breck and coworkers at Uruon Carbide used the modem Lahn alphabet, for example, zeoHtes A, B, X, Y, L. The use of the Greek alphabet was inihated by Mobil and Union Carbide with the zeoHtes alpha, beta, omega. Many of the synthetic zeoHtes which have the structural topology of mineral zeoHte species were assigned the name of the mineral, for example, syn-thehc mordenite, chabazite, erionite and offretite.The molecular sieve Hterature is replete with acronyms ZSM-5, -11, ZK-4 (Mobil), EU-1, FU-1, NU-1 (ICI), LZ-210, AlPO, SAPO, MeAPO, etc. (Union Carbide, UOP) and ECR-1 (Exxon). The one pubHcaHon on nomenclature by lUPAC in 1979 is Hmited to the then-known zeoHte-type materials [3]. 

Key nurds Aniline methylation, molecular sieves, alkali-metal exchanged Y, ALPO, SAPO, NMA, NNDMA, NMT, NNDMT, T. 

Zeolites and zeotypes can be defined as microporous crystalline structures (Figure 1 and Table 1) in which the framework is formed by tetrahedral of silica, in which there is isomorphic substitution with trivalent or tetravalent elements such as for instance Al, Ge, B, Fe, Cr, Ge, Ti, etc. [1]. Similar types of structure can also be achieved with the framework formed by Al and P, with or without other transition metal elements [2]. These types of structure are denoted as AlPOs, SAPOs, and MEAPOs, depending on the composition of the framework [3]. 

Structure type AlPO SAPO MeAPO (Me elements) MeSPO (Me elements)... 

Al/AljOj- based Pseudo- boehmite AlPOs (SAPOs, MeAPSOs) Anodic oxidized Aluminum oxide gels Foams... 

Crystalline molecular sieve zeoHtes, and related molecular sieve materials that are not technically zeoHtes, eg, siHcaHte, AlPO s, SAPOs, etc. 

Other materials, closely related to zeoHtes, with zeo-type structures are silico-aluminophosphates (SAPOs) and aluminophosphates (ALPOs) [6]. 

The 13C MAS NMR spectrum of CAL-4 is reported in Figure 1. For comparison, the spectra of SAPO-44 synthesized by traditional method with CyHA as SDA and of nBA ALPO-kan are also shown. From this figure, we can conclude that CAL-4 contains both nBA and CyHA occluded in the pores. 

Synthetic forms AlPO-34, CoAPO-44, CoAPO-47, DAF-5, GaPO-34, Unde D, Unde R, LZ-218, MeAPO-47, MeAPSO-47, (Ni(deta)2)-UT-6, Phi, SAPO-34, SAPO-47, UiO-21, ZK-14, ZYT-6... 

There is limited patent literature available on manufacturing techniques for aluminophosphates. Although many patents describe AlPO synthesis, most described examples are small-scale preparations. The fact that at least two catalytic applications have been commercialized for SAPO molecular sieves indicates that they have been scaled-up to large quantities [55, 56]. A large-scale preparation of SAPO-34 is described in a recent patent [57]. 

Up to now, a variety of non-zeolite/polymer mixed-matrix membranes have been developed comprising either nonporous or porous non-zeolitic materials as the dispersed phase in the continuous polymer phase. For example, non-porous and porous silica nanoparticles, alumina, activated carbon, poly(ethylene glycol) impregnated activated carbon, carbon molecular sieves, Ti02 nanoparticles, layered materials, metal-organic frameworks and mesoporous molecular sieves have been studied as the dispersed non-zeolitic materials in the mixed-matrix membranes in the literature [23-35]. This chapter does not focus on these non-zeoUte/polymer mixed-matrix membranes. Instead we describe recent progress in molecular sieve/ polymer mixed-matrix membranes, as much of the research conducted to date on mixed-matrix membranes has focused on the combination of a dispersed zeolite phase with an easily processed continuous polymer matrix. The molecular sieve/ polymer mixed-matrix membranes covered in this chapter include zeolite/polymer and non-zeolitic molecular sieve/polymer mixed-matrix membranes, such as alu-minophosphate molecular sieve (AlPO)/polymer and silicoaluminophosphate molecular sieve (SAPO)/polymer mixed-matrix membranes. 

Silicoaluminophosphates (SAPOs), along with their crystalline aluminum phosphate counterparts (ALPOs), first discovered by Union Carbide workers in the early 1970s [41, 42], derive their acidity through the substitution of framework phosphorous by silicon thereby creating the charge imbalance which, when compensated for by protons, creates acidic centers. SAPOs in general have seen limited use in bond-breaking applications primarily due to weaker acidity, framework stability, or technoeconomic reasons. Of the rich variety of structures available,... 

The acidity of thermally stable mesoporous aluminophosphates (AlPO) and sili-coaluminophosphates (SAPO) has also been stndied by microcalorimetry [245]. By contrast with microporous crystalline alnminophosphate molecnlar sieves, mesoporous compounds are amorphous and characterized by Al/P ratios greater than 1. These particularities are responsible for a strong Lewis acidity, making these mesoporous materials more acidic than the microporons analognes, with an amonnt of strong acid sites that increases with the silicon content. 

The concept zeolites conventionally served as the synonym for aluminosilicates with microporous host lattice structures. Upon removal of the guest water, zeolites demonstrate adsorptive property at the molecular level as a result they are also referred to as molecular sieves. Crystalline zeosils, AlPO s, SAPO s, MAPO s (M=metal), expanded clay minerals and Werner compounds are also able to adsorb molecules vitally on reproval of any of the guest species they occlude and play an Important role in fields such as separation and catalysis (ref. 1). Inclusion compounds are another kind of crystalline materials with open framework structures. The guest molecules in an inclusion compound are believed to be indispensable to sustaining the framework structure their removal from the host lattice usually results in collapse of the host into a more compact crystal structure or even into an amorphous structure. 

Of the zeolitic materials, AlPO s cut a conspicuous figure because of their structural diversity and the incorporation of other elements into their frameworks. The recently developed VPI-5 (refs. 2, 3) announced the feasibility of synthesis of micoporous structures with windows comprising rings of over 12-T. All AlPO s, SAPO s and MAPO s form a family of microporous structures constructed by or essentially by A1(I) and P(V). Some of them are isostructural with zeolites but a majority have novel structures. The primary building units (PBU) centred by P(V) are invariantly PO4 whereas those centred by A1(I) are AlO in most cases and AIO5 or even AlOs in a few cases. So far all AlPO s, SAPO s and MAPO s have been synthesized exclusively in the presence of amines or... 

Besides the conventional zeolites, several novel zeolite analogues such as the ALPOs (aluminophosphates), MeALPOs (divalent-metal (Me) substituted aluminophos-phates), SAPOs (silicon substituted aluminophosphates) and so on have been synthesized (Davis Lobo, 1992). Wilson et al. (1982) first reported the synthesis of microporous ALPOs. ALPO synthesis differs from zeolite synthesis in that it involves acidic or mildly basic conditions and no alkali metal ions. Some members in the ALPO... 

Oxides of transition metals can act as acid-base or redox catalysts. Oxides of non-transition metals (AI2O3, SiOj) are, however, good acid-base catalysts. There is a large family of aluminosilicate zeolitic acids (e.g. H -ZSM-5, H-mordenite). Micropor-ous aluminium phosphates (ALPOs) can be modified to yield acidic SAPOs (Si replaces... 

There are 18 reported MeAPO structure-types (Table I). Eight of these are zeolite structure analogs (17, 20, 34, 35, 37, 43, 44, 47) which were subsequently observed In AlPO,-based materials. Seven structure-types were first Identified In the A1P0 (5, 11, 14, 16, 31), SAPO (41), or MeAPSO (46) families (14.15). The remaining structures (36, 39, 50) were first observed In the MeAPO family. The x-ray powder diffraction patterns characteristic of the structure-types 5, 11, 17, and 20 (6.16,17) and 14, 18, and 31 (7) have been previously published. The x-ray powder patterns... 

Along with A1P0 and SAPO, the MeAPO molecular sieves have extended the structural and compositional variety found among the growing numbers of AlPO,-based molecular sieves. Both the metal and the organic template exert a primary influence on... 

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