Doping amphoteric

The physicochemical characterization of the acidity of the doped alumina performed by microcalorimetry, has been complementarized with the catalytic test of 2-propanol decomposition [175], It was found that the modification of y-Al203 surface properties with small amounts of Ca ", Li+, Nd ", NF+, SO/, Zf +ions changed moderately its amphoteric properties. The catalytic test of 2-propanol... 

Here we describe the effect of chromia doping on three different catalysts viz. alumina, zirconia and thoria. The basis for choosing these catalysts and using chromia as a doping are two fold. First literature references clearly indicate that the first two materials when doped with chromia are active for the above mentioned reaction. Thoria whose thermal stability, high selectivity in dehydration reactions are well documented, was tried to compare the activities of acidic catalysts with that of an amphoteric one.(7 8)... 

The main families of amphoteric solids are l)bulk oxides such as Y-AI2O3, Z1O2, Ti02, Ga203, etc, 2) alkali-exchanged zeolites (Li, Na, K, Rb, Cs-X or Y zeolites,. .,), 3) doped and supported oxides (V-MgO,. ..), 4) oxynitrides (ZrPON, AlPON, AIVON). 

Thus, our results oppose the popular opinion, that it is not ix>ssible to sorb simultaneously in comparable amounts chloroplatinate anion and dope cation on the surface of amphoteric and basic supports from the acid impregnating solutions at the synthesis of bimetal catalysts. Note, however, that a noticeable suppression of copper sorption by Pt limits the catalyst synthesis via a simultaneous deposition from the solutions with the known Pt content and Cu/Pt ratio. Our experiment results show, that only for Pt concentrations less than 0.5 wt.% we can obtain a wide range of Cu/Pt ratios. At the Pt concentration exceeding 1 wt.%, the obtained ratio shall be less than 2. Moreover, the registered acceleration of Pt... 

Amphoteric impurities Doping impurities that may act as either a donor or an acceptor. 

There are two common oxidation states, 11 and IV, in tin, and Sn is of more importance in the sol-gel ceramic field. Sn + ions are easily hydrolyzed and stannic acid forms. By low temperature and slow hydrolysis of Sn salts, an amphoteric of-starmic acid is formed, which is soluble in aqueous solutions of acids and bases. The high temperature and rapid hydrolysis of 80 + salts, as well as aging of a-stannic acid , results in -stannic acid or metastannic acid , which is insoluble in solutions of ordinary acids and bases. Both a- and j3-form are rutile-type crystal structure with absorbed water. And it is easy to be dehydrated by heating around 100°C to form crystalline SnOi, cassiterite. The difference between a- and 8-form was attributed to the particle size, though the discussion is open (Bailar et al., 1973). The aqueous solutions were mainly ai lied for fabrication of thin films, such as electrically conductive and optically transparent films doped with Sb + or Nb +, and gas sensing films. 

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