Pore volumes, aluminophosphate

P30s. The various structures exhibit intracrystalline adsorption pore volumes from 0.04 to 0.35 cm3/g, and pore sizes from 0.3 to 0.8nm. The aluminophosphate frameworks are hydrophilic. 

The aluminophosphate oxynitride containing 13.7% nitrogen has been used as support for the preparation of the nickel supported AlPON. Pore volume impregnation with an aqueous solution of nickel formate was used. After impregnation, the solid was dried at 170 °C under a residual pressure of approximately 5 mbar for 12 h. 

IWo methods for the preparation of nickel-loaded AIPO4-5 aluminophosphate were employed by I aushaar-Czarnetzki and van Hooff [27]. Pore volume impregnations with Ni(N03)2 or K2[Ni(CN)4]) salts followed by reduction at... 

The characteristics of aluminophosphate molecular sieves include a univariant framework composition with Al/P = 1, a high degree of structural diversity and a wide range of pore sizes and volumes, exceeding the pore sizes known previously in zeolite molecular sieves with the VPI-5 18-membered ring material. They are neutral frameworks and therefore have nil ion-exchange capacity or acidic catalytic properties. Their surface selectivity is mildly hydrophilic. They exhibit excellent thermal and hydrothermal stability, up to 1000 °C (thermal) and 600 °C (steam). 

VPI-5 is an aluminophosphate framework with very large one-dimensional pores defined by 18-member ring[22]. The crystal structure report[7j of synthesized VPI-5 revealed the possible role of water molecules as templates. The use of VPI-5 as a molecular sieve and as a catalyst primarily depend on the removal of the occluded water molecules without the destruction of the framework structure. Prasad et al.[23] reported from their TGA experiment that the seven distinct types of water molecules could be desorbed from VPI-5 in a step-wise fashion, in the temperature range of 35 to 60°C. The cluster model calculations[24] have revealed the actual electronic interaction of water molecules with VPI-5 framework. CG technique also indicated that the void volume in VPI-5 could be controlled by the partial removal of water molecules. 

PSD s (H-K model) are shown in Figure 4 mean sizes (volume basis) are shown in Table 2. The silicalite ZSM-5 and its higher aluminum companion show peak pore sizes at 5 A and 10 A. The ZSM-11 has a sharp peak at 7.4 A. Both the mildly and severely steamed zeolites have featureless PSD s indicating that most of the micropores are destroyed by steaming. The VPI-5 aluminophosphate has a broad size distribution and mean size of 15.5 A. This compares with a size determined by XRD of 12.6 A (ref. 13). 

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