Zirconium oxide, low

Another type of membrane is the dynamic membrane, formed by dynamically coating a selective membrane layer on a finely porous support. Advantages for these membranes are high water flux, generation and regeneration in situ abiUty to withstand elevated temperatures and corrosive feeds, and relatively low capital and operating costs. Several membrane materials are available, but most of the work has been done with composites of hydrous zirconium oxide and poly(acryhc acid) on porous stainless steel or ceramic tubes. 

The raw materials needed to supply about ten million new automobiles a year do not impose a difficult problem except in the case of the noble metals. Present technology indicates that each car may need up to ten pounds of pellets, two pounds of monoliths, or two pounds of metal alloys. The refractory oxide support materials are usually a mixture of silica, alumina, magnesia, lithium oxide, and zirconium oxide. Fifty thousand tons of such materials a year do not raise serious problems (47). The base metal oxides requirement per car may be 0.1 to 1 lb per car, or up to five thousand tons a year. The current U.S. annual consumption of copper, manganese, and chromium is above a million tons per year, and the consumption of nickel and tungsten above a hundred thousand tons per year. The only important metals used at the low rate of five thousand tons per year are cobalt, vanadium, and the rare earths. 

Tanny (9 ) has prepared ultrafilters by depositing hydrous zirconium oxide on pliable porous materials in a fluted configuration, providing a large membrane area in a small volume suitable for low pressure ultrafiltration. 

A marked influence of the procedure for the addition of cerium was observed in XRD profiles. These profiles suggest that the proportion of zirconium oxide with tetragonal structure, considered as the most stable phase, is higher for procedure A. Important changes with respect to unmodified zirconia were not observed in the case of procedure B. No cerium-containing phases were detected, probably because of the low cerium content of the catalysts. 

Zirconium oxides are extensively used in many fields (such as ceramic, refractory, sensor and catalysis) due to their properties[l]. Many methods have been developed for the production of such materials[2]. Among them. Rapid Thermolysis Approach (RTA) is a safe, simple and instantaneous route. Kingsley firstly reported the preparation of alumina and related oxides by RTA[3]. However, the samples derived showed a relative low BET surface area. ZrOj so-produced has been shown to be highly active towards CO oxidation and methane combustion. In order to have a full understanding of so-derived zirconia, the preparation of zirconia is in the first instance investigated in the present work. 

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