595results about "Rare earth metal oxides/hydroxides" patented technology

A homogeneous ceria-based mixed-metal oxide, useful as a catalyst support, a co-catalyst and / or a getter has a relatively large surface area per weight, typically exceeding 150 m<2> / g, a structure of nanocrystallites having diameters of less than 4 nm, and including pores larger than the nanocrystallites and having diameters in the range of 4 to about 9 nm. The ratio of pore volumes, VP, to skeletal structure volumes, VS, is typically less than about 2.5, and the surface area per unit volume of the oxide material is greater than 320 m<2> / cm<3>, for low internal mass transfer resistance and large effective surface area for reaction activity. The mixed metal oxide is ceria-based, includes Zr and or Hf, and is made by a novel co-precipitation process. A highly dispersed catalyst metal, typically a noble metal such as Pt, may be loaded on to the mixed metal oxide support from a catalyst metal-containing solution following a selected acid surface treatment of the oxide support. Appropriate ratioing of the Ce and other metal constituents of the oxide support contribute to it retaining in a cubic phase and enhancing catalytic performance. Rhenium is preferably further loaded on to the mixed-metal oxide support and passivated, to increase the activity of the catalyst. The metal-loaded mixed-metal oxide catalyst is applied particularly in water gas shift reactions as associated with fuel processing systems, as for fuel cells.

Nanowires useful as heterogeneous catalysts are provided. The nanowire catalysts are useful in a variety of catalytic reactions, for example, the oxidative coupling of methane to ethylene. Related methods for use and manufacture of the same are also disclosed.

The present invention provides a mixed rare earth oxide for the production of a cerium-based abrasive, in which the ignition loss after heating at a temperature of 1,000 DEG C for 1 hour is 0.5 mass% or less on the dry mass basis and the crystallite diameter is from 200 to 400 A; a mixed rare earth fluoride for the production of a cerium-based abrasive, in which the ignition loss is from 3 to 15% on the dry mass basis; a process for producing a cerium-based abrasive from these mixed rare earth oxide or mixed rare earth fluoride; and a cerium-based abrasive produced by using these mixed rare earth oxide or mixed rare earth fluoride.

A mixed light rare earth compound which has been obtained by chemically removing medium-to-heavy rare earth elements, Nd and impurities other than rare earth elements from an ore containing rare earth elements is fired at 500 to 1100° C. to yield a mixed rare earth oxide. A cerium-based rare earth fluoride is added to the mixed rare earth oxide to obtain a mixture. The mixture is subjected to wet-pulverization, drying, firing, disintegration and classification to thereby yield a cerium-containing abrasive.

A mixing reactor for mixing efficiently streams of fluids of differing densities. In a preferred embodiment, one of the fluids is supercritical water, and the other is an aqueous salt solution. Thus, the reactor enables the production of metal oxide nanoparticles as a continuous process, without any risk of the reactor blocking due to the inefficient mixing inherent in existing reactor designs.