LECO combustion analysis

FIGURE 23.20 Effective diffusivity of pentane and heptane imbibed in coked alumina catalyst peUets measiued using PFG-NMR, plotted against coke content of the catalyst determined by LECO combustion analysis. SoUd symbols (pentane), open symbols (heptane). The lines are a linear fit to the data. 

Other major shale constituents such as C, H, N, and S are determined by thermal decomposition and instrumental detection methods. Oxygen is determined by 14 MeV neutron activation analysis. Parr or Leco BTU bomb combustion and subsequent ion chromatographic determination is used for halogens, sulfate and nitrate. Ion chromatography is also suitable for anionic characterization of shale process waters. Two analytical procedures for oil shales should be used with caution. Kjeldahl nitrogen procedure has been found to give reproducible but considerably low results for certain oil... 

The PE 2400 CHN Analyzer (Fig. 4) can be modified to perform automatic determination of oxygen. The combustion tube is filled with platinized carbon reagent. The samples are pyrolyzed in an inert atmosphere of argon or helium. The reaction product CO is separated by frontal chromatography and measured by thermal conductivity. In the Leco CHN Analyzer, carbon monoxide is converted to carbon dioxide to be measured by infrared absorption. Neither CHN method is suitable for the analysis of organic substances which contain fluorine, phosphorus, silicon, or most metallic elements. 

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