Image analysis of X-ray microtomograms of Pd–Ag/SiO2 xerogel catalysts supported on Al2O3 foams

Abstract

In order to preshape and mechanically strengthen, Pd-Ag/SiO 2 xerogel catalysts were carried out in A1 2 0 3 foams (pore-sizes ~40 µm). The final material consists of a Pd-Ag/SiO 2 xerogel immobilized in the open cells of the alumina foam. The localization of the xerogel catalyst in alumina foams of various pore structure was studied by X-ray microtomography. The three-dimensional (3D) porous structure was reconstructed from the consecutive cross-sections obtained by this technique. Total porosity, porous density distribution, and pore-size distribution were determined by image analysis on the free and impregnated supports. Our results show that the success of the used impregnation technique depends on the pore structure of the support.

Pd–Ag/SiO2 xerogel catalyst forming by impregnation on alumina foams

“…Similar activity decreases due to diffusion limitations can be found in the literature [2,3]. The pore size distribution was calculated by image analysis for all three alumina foams [25]. The distribution maximum corresponds to a pore size around 0.15 mm and almost the entire distribution corresponds to pore sizes inferior to 0.4 mm.…”

“…Erosion and dilation can be combined in a variety of ways, in parallel and series, to give other transformations including opening, closing, filling, skeletonisa-tion and many others. The total porosity (ε) and the porosity distribution (δ L ) were calculated from the 3D images, according to the methodology presented previously [25] :…”

X-ray computed micro tomography as complementary method for the characterization of activated porous ceramic preforms

“…This technique allows determination of bulk properties and gathering of localized information at the micron scale, which is essential to understand the factors controlling pressureless infiltration. 31,34,35,[37][38][39][40][41][42][43] The measurement leaves the samples intact, and the infiltration experiments can be made on the same samples.…”

“…Several data procedure techniques have already been developed. [34][35][36][37][38][39][40][41][42][43][44][45][46][47] In the present work, the raw transmission images were backprojected using the ConeRec program from Skyscan, 38 which is based on a modified Feldkamp algorithm 48 [ Fig. 3(a)].…”

“…This method has the additional advantage of being nondestructive. [34][35][36][37][38][39] Limitations of the method are that part of the image treatment such as thresholding of calculated gray scale images and stereological data extraction such as the transformation of the CT data into microstructural parameters (particle diameters, porosity, etc.) are model dependent and may therefore affect the results.…”