Pore size distribution for activated

Figure 6. Pore size distribution for activated carbon (left scale GAC, right scale standard material)...

Fig. 1 Pore size distributions for activated carbon, silica gel, activated alumina, two molecular sieve carbons (MSCs), and zeolite 5A. (From Ref ll)...

Setoyama, N., Suzuki, T., and Kaneko, K. (1998). Simulation study on the relationship between a high resolution a -plot and the pore size distribution for activated carbon. Carbon, 36, 1459—67. 

Figure 3. Pore size distribution for activated carbons...

Pore size optimization is one area where developmental efforts have been focused. Unimodal pore (NiMo) catalysts were found highly active for asphaltene conversion from resids but a large formation of coke-like sediments. Meanwhile, a macroporous catalyst showed lower activity but almost no sediments. The decrease of pore size increases the molecular weight of the asphaltenes in the hydrocracked product. An effective catalyst for VR is that for which average pores size and pore size distribution, and active phase distribution have been optimized. Therefore, the pore size distribution must be wide and contain predominantly meso-pores, but along with some micro- and macro-pores. However, the asphaltene conversion phase has to be localized in the larger pores to avoid sediment formation [134],... 

Table 4.1 Effect of solvent used for dehydrochlorination of the polymer precursor on pore size distribution in activated carbon. Experimental conditions chlorinated PVC was treated with KOH at 20°C for 5 h thermal treatment conditions carbonization at 400°C for 30 min followed by activation with CO at 900°C for 5 min...

The SAXS/TGA approach has been demonstrated to be a useful technique for time-resolution of porosity development in carbons during activation processes. Qualitative interpretation of the data obtained thus far suggests that a population balance approach focusing on the rates of production and consumption of pores as a function of size may be a fruitful approach to the development of quantitative models of activation proces.ses. These then could become useful tools for the optimization of pore size distributions for particular applications by providing descriptions and predictions of how various activating agents and time-temperature histories affect resultant pore size distributions. 

Figure 5. Typical pore size distributions for powdered activated carbons.

Chemical activation is generally carried out with uncarbonized feedstocks, gas activation generally with carbonized feedstocks. The aim of both processes is to convert the particular feedstock into a material with a high specific surface area (BET values between 400 and 2500 m /g) and the optimum pore size distribution for the required application. There are three types of pores ... 

Nam, Eldridge and Kittrell studied the pore size distribution for vanadia/alumina catalysts for the removal of NOx by reaction with ammonia. The pore size distributions are found to change dramatically as sulfur poisons the de-NOx reaction. The smallest pores (<10 nm in radius) are found (by porosimetry) to be filled first. As a result the surface decreases by up to 90% with 12% sulfur content, although the pore volume decreased by only 20%. The associated de-NOx activity decreased substantially. It was proposed that ammonium sulfate, bisulfate, or aluminum sulfate formed on the surface to deactivate the catalyst. 

Fig. 13. Pore size distributions for the WV-A900, BAX 1500 and NP5 active carbons evaluated by using the NLDFT approach [171]...

Micrometries ASAP 2020 was used to obtain the pore volume, BET surface area and pore size distribution of activated samples. The instrument uses the statie volumetrie technique with nitrogen adsorption at 77 K. Known weight of sample was degassed at 573 K for 2 hrs under vacuum and then surface area was determinate by BET method. 

Figure 8. Pore size distributions for Ajax activated carbon from a) Fitting methane adsorption experiment data in Figure 8 and b) Using nitrogen at 77K.

Table 6.12 Pore size distribution for fly ash, activated fly ashes based on BET analysis...

Fig. 2 Pore size distribution of activated carbon Chemviron BPL 4x10 with diffusion regimes for c-hexane...

A major difficulty in testing the validity of predictions from the DR equation is that independent estimates of the relevant parameters—the total micropore volume and the pore size distribution—are so often lacking. However, Marsh and Rand compared the extrapolated value for from DR plots of CO2 on a series of activated carbons, with the micropore volume estimated by the pre-adsorption of nonane. They found that except in one case, the value from the DR plot was below, often much below, the nonane figure (Table 4.9). 

Fig. 7. The effect of preparation on the pore size distribution (a), titanium dispersion (b), and the activity for epoxidation of cyclohexene (c) of titania—siUca containing 10 wt % titania and calcined in air at 673 K. Sample A, low-temperature aerogel Sample B, high-temperature aerogel Sample C, aerogel.

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