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Vapor-solid reactions: formation of an inactive surface layer and/or formation of a volatile compound that exits the reactor. [22] This results in a loss of surface area and/or catalyst material. Solid-state transformation: solid-state diffusion of catalyst support atoms to the surface followed by a reaction that forms an inactive phase. This ...
Homogeneity and heterogeneity; only ' b ' is homogeneous Homogeneity and heterogeneity are concepts relating to the uniformity of a substance, process or image.A homogeneous feature is uniform in composition or character (i.e., color, shape, size, weight, height, distribution, texture, language, income, disease, temperature, radioactivity, architectural design, etc.); one that is heterogeneous ...
A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. [1] Many examples can be found in metallurgy , geology , and solid-state chemistry .
Solid-state chemistry, also sometimes referred as materials chemistry, is the study of the synthesis, structure, and properties of solid phase materials.It therefore has a strong overlap with solid-state physics, mineralogy, crystallography, ceramics, metallurgy, thermodynamics, materials science and electronics with a focus on the synthesis of novel materials and their characterization.
Heterogeneous nucleation, nucleation with the nucleus at a surface, is much more common than homogeneous nucleation. [ 1 ] [ 3 ] For example, in the nucleation of ice from supercooled water droplets, purifying the water to remove all or almost all impurities results in water droplets that freeze below around −35 °C, [ 1 ] [ 3 ] [ 6 ] whereas ...
Three droplets on a surface, illustrating decreasing contact angles. The contact angle the droplet surface makes with the solid horizontal surface decreases from left to right. A diagram featuring all of the factors that affect heterogeneous nucleation. Unlike homogeneous nucleation, heterogeneous nucleation occurs on a surface or impurity.
A common problem in heterogeneous catalysis is leaching, a form of deactivation where active species on the surface of a solid catalyst are lost in the liquid phase. Leaching is detrimental for environmental and commercial reasons, and must be taken into consideration if a catalyst is to be used for extended periods of time.
A suspension is a heterogeneous mixture in which the solid particles do not dissolve, but get suspended throughout the bulk of the solvent, left floating around freely in the medium. [1] The internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation, with the use of certain excipients or suspending ...