Hexane solubles of raw algal cells are shown in Table 5.14. Hexane soluble was obtained at a high yield of 58% of its dry weight and had good fluidity with a vis­cosity of 56 cP and a high heating value (49 MJ/kg). The properties of primary oil are shown in Table 5.15. The yield of the primary oil obtained at 575 K was 52.9% and that at 475 K was 56.5%; these values were slightly lower than the yield of the hexane soluble of the raw algal cells. This suggests that hydrocarbons of raw algal cells were partly converted into dichloromethane insoluble materials such as char (Dote et al. 1994).

The heating value of the primary oil obtained at 575 K was 47.5 MJ/kg and that at 475 K was 42.0 MJ/kg; these values were equivalent to petroleum oil. In particular, the heating value of the primary oil obtained at 575 K was much higher than that of the oil obtained by liquefaction of other biomasses. The viscosity of the primary oil obtained at 575 K was as low (94 cP) as that of the hexane soluble of the raw algal cells. However, the viscosity of the primary oil obtained at 475 K was too high to measure: the primary oil was like rubber. Therefore, the primary oil obtained at 575 K could be used as fuel oil. The oxygen content of the primary oil obtained

at 575 K was slightly higher than that of the hexane soluble of the raw algal cells. However, it was much lower than that of the oil obtained by liquefaction of other biomasses (Dote et al. 1994).

The properties of the hexane soluble of primary oil are shown in Table 5.16. The yield of the hexane soluble of the primary oil obtained at 575 K was 44% and that at 475 K was 39% on a dry-algal-cell basis. This means that the primary oil obtained at 575 K contained 83% of hexane soluble and that at 475 K contained 69% of hexane soluble. The elemental composition of the three hexane solubles was almost equal. The hexane solubles of the primary oil obtained at 575 and 475 K had good fluidity, as did the hexane soluble of the raw algal cells. Despite thermal treatment at high temperature, the hexane soluble of primary oil has properties that are similar to those of the hexane soluble of raw algal cells (Dote et al. 1994). Figure 5.10 shows the liquefaction of algal cells by hexane extraction obtained for primary oil.