Crystal porous

Barrer, R. M. Brit. Chem. Eng. 4 (1959) 267. New selective sorbents porous crystals as molecular filters. 

Fig. 2.20. AFM pictures of (left) a porous crystal made from a core-shell latex the crystalline lattice of the Si02 appears grey while the nanopores are black right) surface of a dried core-shell latex...

Barrer R.M., Bartholomew R.F., and Rees L.V.C. (1963) Ion exchange in porous crystals, II the relationship between self- and exchange-diffusion coefficients. /. Phys. Chem. Solids 24, 309-317. 

Another improvement consisted of preparing low density explosives (L.D. explosives) which contain ammonium nitrate in the form of bulky, porous crystals... 

There are several ways to classify porous crystals. One of these subdivides them according to the strength of bonding as follows. 

Many porous crystals have parallel channels running throughout the structure of the host lattice along which the guest molecules lie. In... 

Table VIII. Some Polyhedra in Porous Crystals (58)...

Amorphous fine-pore Xerogels, fine-pore glasses, many activated charcoals, and porous crystals (type A and X Zeolites). 

In certain cases (e.g., porous crystals) the micropore volume can be determined from structural data. 

Zeolites are crystalline aluminosilicates that are used as catalysts and that have a particular chemical and physical structure (Decroocq, 1984 Goursot et al., 1997). They are highly porous crystals veined with sub-microscopic channels. The channels contain water (hence the bubbling at high temperatures), which can be eliminated by heating (combined with other treatments) without altering the crystal structure (Occelli and Robson, 1989). 

The zeolites are a group of about 50 complex tectosilicates that have a number of industrial uses. These compounds tend to have an open, porous crystal structure and are chemically inert. This makes them useful in filters, water purification, and as fillers in animal feed and soil conditioners. 

As the potentialities of micropores in crystals rather slowly became realised there developed an area of synthetic chemistry which has yielded a remarkable variety of microporous structures. Most are 3-dimensional 4-connected nets, of which the numbers envisaged vastly exceed the numbers prepared experimentally. Accordingly the search for chemical pathways to new porous crystals proceeds apace, both for its scientific interest and its possible industrial rewards. 

This account will emphasise several physico-chemical aspects of synthesis which help in understanding the green fingers" approach of much current research on the formation of porous crystals. 

Stabilising Porous Crystals Host-Guest Solutions... 

The zeolite, porosil or A1P0 is the "host" and the zeolitic component the "guest". The host-guest complex is a solution, amenable at equilibrium to solution thermodynamics (14,15), and the host-guest relationship thereby described is one of the most important in the chemistry of porous crystals because, without the zeolitic guest,... 

The final purity after the pressure sweating step is limited by the melt which adheres at the porous crystal layer. Therefore there is no significant difference between the experiments under 15 bar C02, 50 bar N2 and 175 bar N2 atmosphere which means that there is already enough gas solved at 15 bar CO2 respectively 50 bar N2 in the liquid impurities to transport them with the escaping gas to the crystal layer surface. 

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