Catalytic Effect of Inherently-Water-Soluble Sodium on Zhundong Coal Gasification

Coal loaded with inherently-water-soluble sodium was prepared with dicyclohexyl-18-crown-6 to investigate the effects of inherently-water-soluble sodium on temperature-programmed isothermal gasification. The results were compared with Na2CO3-loaded coal using thermo-gravimetric analysis (TGA), and the results showed that sodium had a catalytic effect on gasification, and water-soluble sodium had a stronger catalytic ability than Na2CO3. The isothermal gasification reaction of inherently-water-soluble-sodium-loaded coal was complete in 4.68 min, whereas that of Na2CO3-loaded coal was complete in 5.39 min. Chemisorption of CO2 to chars was investigated by TGA at 300 C, which showed that the order of CO2 chemisorption capacity was similar to that of the catalytic abilities during gasification. Therefore, the CO2 chemisorption capacity accurately reflects differences in the gasification reactivity. Moreover, the distribution of sodium in coal and char structures were investigated by multiple techniques, including scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). EDS-mapping images of Na-loaded coal indicated that inherently-water-soluble sodium mainly adhered to coal particles. This finding shows that coal graphitization was strongly inhibited by inherently-water-soluble sodium, which further strengthened the chemisorption of CO2 to char and the reactivity of char during gasification.

Effect of amine ligand, copper/amine ratio, and pH on copper adsorption into wood

To measure the chemical adsorption capacity of wood for copper (Cu) and amine in Cu-amine solution, Cu was formulated with different ratios of mono- (Mea), di- (Dea), tri- (Tea) ethanolamine, ethylenediamine (En) and ammonia (Am), and the Cu adsorption was compared with the cation exchange capacity (CEC) of red pine (Pinus resinosa Ait.). The chemisorption capacity of the wood for Cu was highly pH dependant and varied with ligand types investigated in this study. Although wood chemisorption capacity increases with pH, high amine ratio Cu-ethanolamine complexes showed very limited adsorption at high pH owing to competition with free ethanolamine in combination with the formation of uncharged ion complexes. During Cu-Mea treatment, negligible Cu2+ was converted to Cu+ and no significant delignification was detected even at very high Mea ratios. Cu appeared to be adsorbed as if it were singly charged, even though most of the complexes present are 2+ charged. The three ethanolamine ligands generally showed similar adsorption tendencies, although their pH dependencies differed. Cu in En was much less adsorbed at intermediate pH compared with the CEC, but had higher adsorption at high pH. Cu in Am also showed higher adsorption at high pH compared with Mea and the [Cu(NH3)(H2O)5]2+ form of Cu might be fixed in wood.

Relation between reduction and sulphidation process during the activation of a Co-Mo/Al2O3 hydrodesulphurization catalyst

The course of activation at 673 and 773 K of an industrial hydrodesulphurization catalyst CHEROX 36-01 was followed gravimetrically. Reduction with hydrogen, reductive sulphidation with a H2S/H2 mixture, non-reductive sulphidation with a H2S/He mixture and sulphidation of prereduced catalysts were compared. All sulphidation procedures are much faster than the reduction alone, the latter has, however, a higher apparent activation energy. In the reductive sulphidation with H2S/H2, reduction and sulphidation take place simultaneously, sulphidation being a predominant process at the beginning of the activation, especially at 673 K. It has been shown how the two processes can be decoupled or superposed. The catalytic activity in ethylene hydrogenation develops much more slowly when the catalyst is activated only by reduction than when it is activated by reductive sulphidation, in accordance with the relative velocities of these two activation procedures. The hydrogenation activity of catalysts reduced to a different extent correlates with their oxygen chemisorption capacity at 195 K.