Effect of Metal Compounds on Pyrolysis Profiles of Douglas Fir

A New Pyrolysis of Metal Hydroxide-Mixed Waste Biomass with Effective Chlorine Removal and Efficient Heat Recovery

“…In contrast, when the samples were further carbonized to higher temperatures (400 °C), the chars obtained from the samples blended with NaOH and KOH via the wet-blending method have relatively higher yields, of 42.8 and 36.9 wt %, respectively, whereas the char yield of the samples without additives decreased extremely to 24.6 wt %. These results are in agreement with those reported by Ohmukai et al, , that char yield significantly increased with the suppression of tar evolution via the effect of alkali-metal hydroxides added in a cellulose structure. Moreover, the metal hydroxide additives may effectively cause cross-linking in the biomass structure, via dehydration, to obtain a higher char yield, even in the coexistence of PVC in the woody biomass samples.…”

“…We found that the tar yield was almost 0% after woody biomass samples were carbonized at 500 °C with NaOH as additives, but the tar yield was 36% after carbonizing woody biomass samples at 500 °C without additives. 17 Therefore, since tar release from woody biomass also can be suppressed by the effect of the additives during carbonization, the char obtained at high yield can be further used effectively for a heat recovery system with simplified tar combustion and chlorine removal processes, as shown in Figure 5.…”

“…Consequently, we have further studied the effect of sodium hydroxide (NaOH) on the pyrolysis profile, to clarify the validity of the proposed method for tar suppression during pyrolysis. Through pyrolysis of a NaOH-loaded Douglas fir at 500 °C, a relatively high yield of char at 32 wt % and no tar products were obtained, because the dehydration reaction to form cross-linked structure was further proceeded by the effect of added alkali metal. , This suggests that the new biomass pyrolysis process with effective tar suppression and energy recovery can be proposed by adding metal hydroxide additives to the biomass structure. However, the waste from construction sites often includes waste woody board that has wallpaper (which is made from poly(vinyl chloride), PVC) affixed to it, or waste woody chips including crushed pipe made from PVC, and so on.…”