Phosphate zirconium

The Tokuyama Soda single-step catalyst consists of a zirconium phosphate catalyst loaded with 0.1—0.5 wt % paHadium (93—97). Pilot-plant data report (93) that at 140°C, 3 MPa, and a H2 acetone mole ratio of 0.2, the MIBK selectivity is 95% at an acetone conversion of 30%. The reactor product does not contain light methyl substituted methyl pentanes, and allows MIBK recovery in a three-column train with a phase separator between the first and second columns. 

Sodium hydrogen zirconium phosphate [34370-53-17 is an ion-exchange material used in portable kidney dialysis systems which regenerate and reckculate the dialysate solution. The solution picks up urea during the dialysis. The urea reacts with urease to form ammonia, which is absorbed by the sodium hydrogen zirconium phosphate. 

Zirconium phosphate [13772-29-7] also absorbs cesium and other radioactive-decay daughter products, and has been proposed as part of permanent disposal systems for nuclear fuel waste processing. 

The main interest in zirconium phosphates relates to their ion-exchange properties. If amorphous zirconium phosphate is equiUbrated with sodium hydroxide to pH 7, one hydrogen is displaced and ZrNaH(P0 2 3H20 [13933-56-7] is obtained. The spacing between the zirconium layers is increased from 0.76 to 1.18 nm, which allows this phosphate to exchange larger ions. 

The gels precipitated as described above are not useful in ion-exchange systems because their fine size impedes fluid flow and allows particulate entrainment. Controlled larger-sized particles of zirconium phosphate are obtained by first producing the desired particle size zirconium hydrous oxide by sol—gel techniques or by controlled precipitation of zirconium basic sulfate. These active, very slightly soluble compounds are then slurried in phosphoric acid to produce zirconium bis (monohydrogen phosphate) and subsequently sodium zirconium hydrogen phosphate pentahydrate with the desired hydrauhc characteristics (213,214). 

Although zirconium phosphate is insoluble in acids, it is easily hydrolyzed in excess caustic to give hydrous zirconium oxide. Zirconium phosphate forms soluble complexes with a large excess of zirconium oxide chloride, and therefore separation of phosphoms from zirconium oxide chloride solutions is difficult (215). 

The properties and behavior of double phosphates such as — Y)3 (216), sodium—zirconium phosphate—siUcates (217), and... 

Hemodialysis with microencapsulated urease and an ammonia ion adsorbent, zirconium phosphate [13772-29-7], has been used (247) to delay the onset of dialysis therapy in patients retaining some renal function, and to reduce the time between dialysis treatment. 

Inspired by the separation ability of cyclic selectors such as cyclodextrins and crown ethers, Malouk s group studied the synthesis of chiral cyclophanes and their intercalation by cation exchange into a lamellar solid acid, a-zirconium phosphate aiming at the preparation of separation media based on solid inorganic-organic conjugates for simple single-plate batch enantioseparations [77-80]. 

An example of the modular preparation of the cyclophane 3 from the substituted bipyridine 2 and a general tripeptide 1 is shown in Scheme 3-3. The host molecule 3 contains a pre-organized binding pocket. The overall basicity of such molecules also facilitates their intercalation within the lamellas of acidic zirconium phosphate, thus making this chemistry well suited for the desired application. 

The water elimination reactions of Co3(P04)2 8 H20 [838], zirconium phosphate [839] and both acid and basic gallium phosphates [840] are too complicated to make kinetic studies of more than empirical value. The decomposition of the double salt, Na3NiP3O10 12 H20 has been shown [593] to obey a composite rate equation comprised of two processes, one purely chemical and the other involving diffusion control, for which E = 38 and 49 kJ mole-1, respectively. There has been a thermodynamic study of CeP04 vaporization [841]. Decomposition of metal phosphites [842] involves oxidation and anion reorganization. 

Layered inorganic solids have been used for site isolation, for example, nickel phosphine complexes confined within the interlayer spaces of sepiolite have been used as olefin hydrogenation catalysts [63], and similarly there has been the encapsulation of metal complexes into zirconium phosphates [64], The principal idea is illustrated in Figure 5.8. The metal complex can be encapsulated by covalent means (a) or by non-covalent interactions (b). 

Figure 5.8 Entrapment of metal complexes into layered zirconium phosphates, (a) Covalent attachment ofthe complex (b) the complex held in place by non-covalent interactions. Reproduced with permission from [64],...

Fig. 1.19 Intercalation of enzymes at the galleries of layered a-zirconium phosphate following a delamination-restacking mechanism.

Kaschak, D.M., Jhonson, S.A., Hooks, D.E., Kim, H.-N., Ward, M.D. and Mallouk, T.E. (1998) Chemistry on the edge A microscopic analysis of the intercalation exfoliation, edge functionalization and monolayer surface tiling reactions of alpha-zirconium phosphate. Journal of the American Chemical Society, 120, 10887-10894. 

Kumar, C.V. and Choudhari A. (2000) Proteins immobilized at the galleries of layered alpha-zirconium phosphate structure and activity studies. Journal of the American Chemical Society, 122, 830-837. 

Layered phosphate/phosphonate and phosphonate materials, obtained by substitution of the phosphate moiety by phosphonate groups, display interesting tunable hydrophilic/organophilic properties for adsorption processes. When Candida rugosa lipase (CRL) is simply equilibrated with zirconium phosphate and phosphonate [135,136], immobilization was demonstrated to take place at the surface of the microcrystals. However, because lipase exhibits a strong hydrophobic character, its uptake by zirconium phosphate and phosphonate was much more related to the hydrophobic/hydrophilic character of the supports than to the surface area properties. A higher uptake is observed for zirconium-phenylphosphonate (78 %)... 

LiNa Geng et al. realized similar experiments for the adsorption of trypsin [141] and hemoglobin [142] on y-zirconium phosphate (y-ZrP) and organo y-ZrP intercalated with butylammonium (BA) and tetrabutylammonium (TBA). Hb adsorbed in the galleries of BA-y-ZrP and TBA-y-ZrP mainly by hydrophobic... 

A limited amount of work has been carried out using zirconium phosphates, compounds with well-defined coagulation and adsorption properties. The efficiency of coprecipitation was about 70% for free amino acids and albumin. 

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