Typical Aluminophosphate Syntheses

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]. 

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A typical synthesis procedure involves the following steps (i) alumina is slurried in water, (ii) phosphoric acid is diluted in water, (iii) the phosphoric acid solution is added to the alumina slurry, (iv) the aluminophosphate precursor mixture is aged at ambient conditions, (v) an organic is added to the precursor mixture and aged with rapid agitation to form the final gel, which (vi) is charged into the autoclave and heated. The gel composition can be written as... 

The synthesis and characterization of a mesoporous silicoalumino phosphate are given employing typical structure directing reagent viz. cetyltrimethyl ammonium bromide. The Si MAS NMR showed that silicon is found in coordination with 1, 2, 3 and 4 A1 ions through oxygen bridges. The sorption characteristics of this new mesoporous SAPO material are also presented. Keywords Silico aluminophosphate, Mesoporous, ordered molecular arrays, MAS NMR. 

In a typical synthesis, 4.2 g. pseudoboehmite (Catapal B, 73% AI2O3) was dispersed in 15.0 g. water. 6.93 g. orthophosphoric acid (85%, S. D. Fine Chemicals) was diluted in 9.7 g. water and then added to a dispersed pseudoboehmite in water. The aluminophosphate gel thus obtained was aged for 24 hours and 3.91 g n-DBA (99%, Riedel-de Haen) was added to the aged gel. The mixture was stirred for 10 minutes and then crystallized in a stainless steel autoclave between 415-418K for 24 hours. After crystallization the autoclave was quenched... 

Dimethylether. Several strategies for the production of dimethyl ether (DME) are described, e.g. direct synthesis from syngas according to equation (8.5) or via dehydration of methanol according to equation (8.6). From a mechanistic point of view direct synthesis proceeds also via methanol formation and subsequent release of water but without procedural isolation of methanol. The process can also be designed to yield both methanol and DME. Established methanol catalysts are employed for methanol formation and typical dehydration catalysts are solid-acid catalysts, e.g. alumina, silica-, phosphorus- or boron-modified alumina, zeolite, (sili-co)aluminophosphates, tungsten-zirconia or sulfated-zirconia. " ... 

Related compounds can be prepared using different metal atoms, like iron, ruthenium, copper or tin, and with differing guest species like ferrocene, co-baltocenixim, tetra- -butylanunonium, tetraethylanunonium, and methylvio-logen. The list of guest species su ests a strong similarity to aluminosilicate or aluminophosphate molecular sieves, since several of these molecules are typical templates for zeolite synthesis. 

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