Structure factor intraparticle

What is the definition of the form factor (or intraparticle structure factor) ... 

The structure of quaternary onium ion active sites was one of the first parameters to be studied 53-89>. Valid comparisons of active site structure can be made only if all other variables are kept constant. Ideally mass transfer and intraparticle diffusion should not be rate limiting factors. With 7-10% RS, 2% CL polystyrenes the tri-n-butyl and tri-n-octylammonium ions 7 and 8... 

The catalytic reaction rate is limited by the intraparticle mass transfer rate. If the rate is relatively slow, both activity and selectivity are lowered. As a result, the support must have a low pore diffusional resistance (high effectiveness factor). For a given pore volume, the surface area and the strength of the support increase as the pore diameter decreases, and the pore diffusional resistance decreases as the pore diameter increases. Thus, an appropriate pore structure must be determined for the support to achieve optimal catalytic performance. 

The intrinsic activity depends on the chemical and physical properties of the active component. For unsupported catalysts, the most important properties are the composition and structure of the catalyst surface and the presence, or absence, of special sites such as Br0nsted or Lewis acid centers, anion or cation defects, and sites of high coordination. For supported catalysts, the size and morphology of the dispersed phase are of additional importance. If intraparticle transport of reactants occurs with a characteristic time that is short compared to that of the reaction, then the observed and intrinsic rates of reaction will be identical. When the characteristic time for intraparticle mass transport is less than that for reaction, the observed rate of reaction per unit mass of catalyst becomes less than the intrinsic value, and the reaction kinetics are dominated by the effects of intraparticle mass transport. The factors governing intraparticle transport are the diffusivities of the reactants and products and the characteristic distance for diffusion. 

Here, P(Q) is the forni factor, which relates to intraparticle correlations and gives infomiation about the internal structure of a single particle. It can be defined as ... 

The intraparticle scattering factor P(Q), is related to the structural properties of the scatterer and is the term that contains particle size information. For extremely small noninteracting particles where r A, P(Q) approaches unity, and the scattering is said to be isotropic. In this situation Equation [12] greatly simplifies and I(Q) For uniform spherical or globular particles this means that I(Q) If concentrations can be accurately determined by alternative means, then the radius of an unknown particle can be obtained by simple ratios, provided the unknown and the known particles have identical refractive indices. 

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