Catalyst size distributions from X-ray diffraction

Abstract

Listen

Translate article

Both the average metal crystallite size and the size distribution can be obtained from Fourier analysis of X-ray diffraction peaks from supported metal catalysts. The average size is obtained from the first derivative of the cosine coefficients (after correction for instrumental effects and microstrain), and the distribution from the second derivative. The advantage of this procedure over, say, electron microscopy is the good sampling associated with a large cross-section of X-ray beam. Furthermore, the weighting of the distribution determining the average size is the same as for chemisorption, so that direct comparisons are possible, / where L is the size.