Amorphous components silica

An amorphous component such as silica-alumina is added to the catalyst, for a sort of pre-cracking of the large molecules (greater than about C25), which cannot enter the zeolite pores. The smaller fragments may then react in the zeolite. Middle distillates maximum yield is achieved by the use of dealuminated Y zeolites. 

The main components of FCC catalysts are Zeolite Y, e.g., REY orUSY as the major active component (10 to 50%), and a binder that is typically an amorphous alumina, silica-alumina, or clay material. In addition to these main components, other zeolite components, e.g., ZSM-5, and other oxide or salt components are quite frequently used additives in the various FCC catalysts available on the market. The addition of 1 to 5% ZSM-5 increases the octane number of the gasoline. ZSM-5 eliminates feed compounds with low octane numbers because it preferentially center-cracks n-paraffins producing butene and propene [14], These short-chain olefins are then used as alkylation feedstocks... 

Chem. Descrip. Amorphous hydrated silica, org. surf, treatment Uses Matting agent in add-ca zed systems, board and industrial coatings, coil arid can coatings (> 0.75 mil) high solids systems (> 0.75 mil), radiation-cured systems (> 0.75 mil), kyd urea systems, water-based coatings, 2-component polyurethane systems Features High porosity... 

Two types of toothpaste formulation predominate, lype 1 is a low abrasive—high solvent toothpaste (Table 5.1) (13) type 2 is a high abrasive—low solvent toothpaste (Table 5.2) (14). The most important differences are the ratio of humectant to abrasive and the nature of the abrasive. Type 1 dentifrices were introduced nationally to the U.S. market in 1970 and now constitute the predominant type. Type 2 dentifrices represent a popular earlier formulation, in which economic and scientific considerations related to the abrasive and humectant favored use of a maximum amount of the abrasive component. All type 1 dentifrices of the early 1990s contain an amorphous hydrated silica powder as the abrasive. Type 2 dentifrices may contain one or more of many insoluble minerals. 

Examination of the infrared spectrum of a pure well-crystallized clay mineral can yield considerable information on its structure and composition in some instances, a species can be more quickly and more fully defined in structure and composition by this technique than by any other single technique. Few soil clays, however, are single species. In general, they are a complex mixture, which may include several layer silicates (either interstratified or as separate species), feldspars, various forms of silica, oxides and hydroxides of iron and aluminum, carbonates, sulphates, and phosphates. These minerals may well be poorly ordered, and associated with varying amounts of amorphous material. Not infrequently amorphous components predominate. As isolated, the clays may contain considerable amounts of organic matter, firmly combined with the inorganic constituents. 

The preparation and properties of a novel, commercially viable Li-ion battery based on a gel electrolyte has recently been disclosed by Bellcore (USA) [124]. The technology has, to date, been licensed to six companies and full commercial production is imminent. The polymer membrane is a copolymer based on PVdF copolymerized with hexafluoropropylene (HFP). HFP helps to decrease the crystallinity of the PVdF component, enhancing its ability to absorb liquid. Optimizing the liquid absorption ability, mechanical strength, and processability requires optimized amorphous/crystalline-phase distribution. The PVdF-HFP membrane can absorb plasticizer up to 200 percent of its original volume, especially when a pore former (fumed silica) is added. The liquid electrolyte is typically a solution of LiPF6 in 2 1 ethylene carbonate dimethyl car-... 

Weight percent profiles through first-stage (left) and second stage reactor of a) alkanes (full fines) and cycloalkanes (dashed fines) and b) aromatic components. Thick lines correspond to C23 finctions, thin lines to 23 fractions. Operating conditions p, 17.5 MPa LHSV 1.67 niL (nv hf molar H2/HC 18 Tmiei 661 K (reactor 1) 622 K (reactor 2). Catalyst NiMo on amorphous silica-alumina. 

In the calculation results (Fig. 24.1), amorphous silica, calcite (CaCCF), and sepiolite precipitate as water is removed from the system. The fluid s pH and ionic strength increase with evaporation as the water evolves toward an Na-C03 brine (Fig. 24.2). The concentrations of the components Na+, K+, Cl-, and SO4- rise monotonically (Fig. 24.2), since they are not consumed by mineral precipitation. The HCO3 and Si02(aq) concentrations increase sharply but less regularly, since they are taken up in forming the minerals. The components Ca++ and Mg++ are largely consumed by the precipitation of calcite and sepiolite. Their concentrations, after a small initial rise, decrease with evaporation. 

The acid component of a hydrocracking catalyst can be an amorphous oxide, e.g., a silica-alumina ora zeolite, eg., USY. This component usually serves as a support for the metal compound responsible for the hydrogenation function. The metal compound can be a noble metal, e.g., Pt or Pd, or a mixture of sulfides, e.g., of Ni/Mo, NiAV, or Co/Mo. The relative amounts of the respective compounds have to be thoroughly balanced to achieve an optimum performance. 

The nuisance dust aspect of bauxite is in sharp contrast to the limited industrial situation where lung injury was reported in Canadian workers, who in the 1940s engaged in the manufacture of alumina abrasives in the virtual absence of fume control. Fusing of bauxite at 2000°C gave rise to a fume composed of freshly formed particles of amorphous silica and aluminum oxide. Despite the poor choice of the term—bauxite fume pneumoconiosis—sometimes used to describe the disease, scientific opinion favors the silica component as the probable toxic agent. It should be emphasized that bauxite from some sources may contain small amounts of silica. 

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