Scanning electron microscopy monoliths

Fig. 6.12 Scanning electron microscopy images of a sol-gel derived column material (A) a rigid rod and (B) a magnification of the bimodal pore structure in the resulting monolithic material [28]. Adapted with permission from the American Chemical Society.

Fig. 13 Scanning electron microscopy images of non-grafted core monolith at (a) 3,000x and (b) 10,000x magnification, and of grafted BV-mMIP monolith at (c) 3,000x and (d) 10,000x magnification. Reproduced with permission from [179]...

Fig. 14 Scanning electron microscopy images of the silica-based MIP monolith cross-section of the formed monolith magnified (a) 800x and (b) 5,000 x. Reproduced with permission from [184]...

The free radical polymerisation of commercial divinylbenzene led to a crosslinked macroporous monolith. The overall interconnected open-cellular macrostructure of the material can be clearly seen by scanning electron microscopy (fig.l). 

The catalysts were characterized using the following techniques BET siuface area measmement, gas porosimetry, hydrogen-oxygen titration, carbon monoxide chemisorption, scanning electron microscopy, and X-ray diffiaction. Prior to characterization, the entire monoliths were crushed and sieved to a particle size less than 250 pm (60 mesh). 

Porosity and pore-size distributions were determined by gas adsorption and immersion calorimetry, with the measurement of helium and bulk densities. Volumes of micropores were calculated using the Dubinin-Radushkevich (DR) equation (Section 4.2.3) to interpret the adsorption isotherms of N2 (77 K), CO2 (273 K) and n-C4H o (273 K). Volumes of mesopores were evaluated by subtracting the total volume of micropores from the amount of nitrogen adsorbed at p/p° = 0.95. The two density values for each carbon were used to calculate the volume of the carbon skeleton and the total volume of pores (including the inter-particle space in monolithic disks). Immersion calorimetry of the carbon into liquids with different molecular dimensions (dichloromethane 0.33 run benzene 0.37 nm and 2,2-dimethylbutane 0.56 nm) permits the calculation of the surface area accessible to such liquids and subsequent micropore size distributions. The adsorption of methane has been carried out at 298 K in a VTI high-pressure volumetric adsorption system. Additional techniques such as mercury porosimetry and scanning electron microscopy (SEM) have also been used for the characterization of the carbons. 

Wash-coat separated from the cordierite monolith by scraping was examined directly by two electron microscopy techniques CTEM (Conventional Transmission Electron Microscopy) and STEM (Scanning Transmission Electron Microscopy). 

Electron microscopy data show that the initial PORP film has oval-shaped pores whose longer side is aligned perpendicular to the axis of extrusion and is a few micrometers while the width does not exceed 1 /tm. The pores walls are connected by bars of 0.1-0.2 /xm thickness oriented parallel to one another and parallel to the direction of extrusion (see Fig. 2). The porous domains alternate with the monolithic ones. Scanning electron micrographs of the spallings parallel (Fig. 3a) and perpendicular (Fig. 3b) to the direction of extrusion show that the oval-shaped pores... 

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