Liquefaction solvents

Conclusions. The quality of liquefaction solvent is an extremely important factor in liquefying coal at conventional or short residence time liquefaction conditions. The ability to alter the quality of this solvent by recycle of certain SRC... 

Liquefaction Solvents. The solvents used in the present study are listed in Tables 2 and 3. Alkylated and hydrogenated pyrenes were synthesized by Friedel-Crafts and Birch reduction, respectively. Details have ° been described in another place (9). 

Liquefaction of fusible coal at high temperature. The liquefaction of Itmann coal, of which softening point and maximum fluidity temperature are 417° and 465°C, respectively, was carried out at several temperatures using decacyclene as a liquefaction solvent. 

The fusible coals can give a high liquefaction yield if the high fluidity during the liquefaction is maintained by the liquefaction solvent to prevent the carbonization. The properties of the solvent required for the high yield with this kind of coal are miscibility, low viscosity, radical quenching reactivity and thermal stability not to be carbonized at the liquefaction temperature as reported in literatures (12). 

Failure of hexylpyrene as the liquefaction solvent may be due to the easy dealkylation (13) or high carbonization reactivity probably catalyzed by coals. Transalkylation for coal-liquefaction may require the acid-catalyst (14) or high pressure (15). 

Stephens, H. P., and Kottenstette, R. J., The Kinetics of Catalytic Hydrogenation of Polynuclear Aromatic Components in Coal Liquefaction Solvents. In Am. Chem. Soc. Div. Fuel Chem, 1985. Prepr. Pap. 30 pp. 345-353. 

The weight percents of coal converted to hexane insolubles in Scheme C and to HC1 precipitates in Schemes A and B are listed in Tables VIII and IX. The extract values given for Schemes A and B have been corrected for the HC1 extract found in the liquefaction solvent. Elemental analyses of various extract and raffinate phases produced by applying Schemes A, B, and C in Table VIII are presented in Table X. 

Liquefaction solvent composition PEG-400/glycerin/H2S04 = 80 20 3 (by weight). Reaction temperature 150 C. 

Figure 1 Solvent-insoluble residue of liquefied wood in different binary systems as functions of the mixing ratios of the two solvents. Note liquefaction solvent composition PEG-400/glycerin/H2S04 80 20 3, liquid ratio 2, reaction time 90 min.

Fig. 2 Effect of solvent and time on the liquefaction of DDG. [Liquefaction solvent/DDG ratio (g/g) 4 catalyst content 3% liquefaction temperature 160 °C], Error bars represent standard deviations calculated from the data obtained from three replicated experiments...

Liquefaction yield achieved by the liquefaction process were 80-98%, indicating that the selected liquefaction conditions, such as temperature, time, sulfuric acid content, and liquefaction solvent to DDG ratio, promoted the atmospheric pressure liquefaction process. These results are summarized in Table 1. Clearly, an increase in liquefaction time and temperature results in increased liquefaction yield. For instance, when the temperature was 160 °C, the liquefaction yield reaches 94.6% at 2 h, whereas further increase in temperature and time resulted in a depressed increase in liquefaction yield. A similar trend has also been observed in the case of liquefaction of com stover [3]. Typically, the increase of catalyst content should increase in the liquefaction yield. As can be seen in Table 1, 94.6% liquefaction yield was obtained at 3% sulfuric acid in 160 °C 2 h. However, the use of sulfuric acid will cause condensation of degraded residues and increase the viscosity of the liquefied materials. The amount of insoluble residue increased with decreasing liquefaction solventDDG ratio. When the liquefaction solvenl/DDG ratio reaches 5, the liquefaction yield is 97.8% after 2 h. A higher yield could be expected at even bigher liquelaction solvent/DDG ratio, but at the cost of more solvents or lower productivity. 

An inverse decreasing relationship was found between the hydroxyl value and the reaction time for the liquefaction system. Figure 5 shows the hydroxyl value decreased steadily from h 0 to h 1.5 and then increased slightly until the end of the liquefaction (h 3). Such decrease in hydroxyl number resulted from dehydration and thermal oxidative degradation of the liquefaction solvent (ethylene carbonate). Yao et al. [7] also reported that alcohol-D-glycosides were produced by the liquefaction between polysaccharides and ethylene glycol under a temperature of 150 °C and catalyst (sulfuric acid) concentration of 3% as used in their... 

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