摘要:
A catalyst composition comprises a particulate support and catalyst nanoparticles on the particulate support. The catalyst nanoparticles comprise an alloy of platinum and palladium in an atomic ratio of from about 25:75 to about 75:25 and are present in a concentration of between about 3 and about 10 wt % weight percent of the catalyst composition. The catalyst composition has an X-ray diffraction pattern that is substantially free of the (311) diffraction peak assignable to PtxPd1-x, where 0.25≦x≦0.75.
摘要:
In a first aspect, the process includes utilizing a precursor medium comprising particles and a nongaseous precursor to form product nanoparticles having a core/shell structure. In another aspect, the process includes utilizing an emulsion precursor medium comprising a nongaseous precursor and two liquid vehicles, wherein one of the liquid vehicles provides desirable thermal effects upon combustion. In another aspect the flame spray process includes modifying solid particles in a flame spray process to change the phase thereof.
摘要:
The invention relates to a process for decreasing flame temperature in a flame spray reaction system, the process comprising the steps of providing a precursor medium comprising a precursor to a component; flame spraying the precursor medium under conditions effective to form a population of product particles; and decreasing the flame temperature by contacting the flame with a cooling medium. The process of the present invention allows for the control of the size, composition and morphology of the nanoparticles made using the process. The invention also relates to a nozzle assembly that comprises a substantially longitudinally extending atomizing feed nozzle that comprises an atomizing medium conduit and one or more substantially longitudinally extending precursor medium feed conduits. The nozzle assembly of the present invention is used in a flame spray system to produce nanoparticles using the processes described herein.
摘要:
In one aspect, the process includes providing a precursor medium comprising a liquid vehicle and a precursor to a component, and flame spraying the precursor medium under conditions effective to form a population of nanoparticles, wherein the nanoparticles include the component. The population of nanoparticles, as formed, comprises less than about 5 percent by volume particles having a particle size greater than 1.0 μm. A size distribution of the population of nanoparticles may have a d50 value less than about 500 nm, and it may be unimodal. The size distribution may have a geometric standard deviation of less than about 2. The process may occur continuously for at least four hours or more. Greater than about 90 percent by weight of the precursor to the component in the precursor medium may be converted to the component in the nanoparticles. The process typically occurs in an enclosed flame spray reactor.
摘要:
The present invention provides a cerium oxide particulate composition and a process for preparing a cerium oxide particulate composition comprising aggregates of approximately spherical primary particles of cerium oxide. The method involves preparing a solution of a cerium oxide precursor, aerosolizing the cerium oxide precursor solution, and heating the aerosol to provide the cerium oxide particle composition.
摘要:
The present invention provides a cerium oxide particulate composition and a process for preparing a cerium oxide particulate composition comprising aggregates of approximately spherical primary particles of cerium oxide. The method involves preparing a solution of a cerium oxide precursor, aerosolizing the cerium oxide precursor solution, and heating the aerosol to provide the cerium oxide particle composition.
摘要:
The invention provides a process for the production of fumed silica. The process comprises providing a silicon halide feedstock comprising about 80% to 100% methyltrichlorosilane, combining the silicon halide feedstock with hydrogen gas and oxygen gas to form a reactant mixture, discharging the reactant mixture out of a burner, and combusting the hydrogen gas and the oxygen gas of the reactant mixture so as to hydrolyze the silicon halide feedstock to produce fumed silica. Hydrogen (H2) is present in a mole fraction of about 0.11 or less based on the reactant mixture, and/or the velocity of the reactant mixture upon exiting the burner is about 25 m/s or more.
摘要翻译:本发明提供一种生产热解二氧化硅的方法。 该方法包括提供包含约80%至100%甲基三氯硅烷的卤化硅原料,将卤化硅原料与氢气和氧气组合以形成反应物混合物,将反应物混合物排出燃烧器,并将氢气和 氧化反应混合物的氧气,以便将卤化硅原料水解以产生热解二氧化硅。 氢(H 2 H 2)以基于反应物混合物的约0.11或更低的摩尔分数存在,和/或离开燃烧器时反应物混合物的速度为约25m / s或更高 。
摘要:
The invention is to processes for producing a nanoglass powder batches and to powder batches formed by such processes. In one embodiment, the process comprises the steps of providing a precursor medium comprising a first metal oxide precursor to a first metal oxide, a second metal oxide precursor to a second metal oxide, and a liquid vehicle; and flame spraying the precursor medium under conditions effective to form aggregated nanoglass particles comprising the first and second metal oxides, wherein the aggregated nanoglass particles have an average primary particle size of from 25 nm to 500 nm. The aggregated nanoglass particles preferably have an average aggregate particle size of from 50 nm to 1000 nm and may be amorphous or crystalline.
摘要:
The present invention relates to a method of making nanoparticulates in a flame reactor, the nanoparticulates having controlled properties such as weight average particle size, composition and morphology. The nanoparticulates made with the method of present invention may be tailored to a specific weight average particle size range, such as from about 1 nm to about 500 nm. In addition to weight average particle size, the nanoparticulates made with the method of the present invention may include a variety of materials including metals, ceramics, organic materials, and combinations thereof. Moreover, the method of the present invention allows control over the morphology of the nanoparticulates, which allows the production of nanoparticulates with any desired morphology including spheroidal and unagglomerated; and agglomerated (aggregated) into larger units of hard aggregates.