Polycondensation of kraft-lignin toward value-added biomaterials: carbon aerogels

Figures & data

Figure 1. Polycondensation reaction of guaiacyl units from lignin with formaldehyde

Figure 2. From left to right: hydrogel, aerogel and carbon aerogel for a formaldehyde–lignin ratio of 1 (F/L 1)

Figure 3. Correlation of initial formaldehyde–lignin mass ratio (F/L) and the specific BET surface area (S_BET) for the resulting aerogels

Table 1. Formaldehyde-lignin mass ratio (F/L) of each reaction mixture and specific BET surface area (S_BET) of the respective aerogel and carbon aerogel

F/L	SBET/m2 g^−1
	Aerogel	Carbon- aerogel
1	293	419
2	279	443
3	253	596

Figure 4. Pore size distributions of the aerogels (red) and carbon aerogels (black) made from solutions of varying formaldehyde–lignin mass ratios (F/L), where d_P is the pore diameter and V the relative pore volume

Figure 5. Pore size distributions of the aerogels (red) and carbon aerogels (black) made from solutions of varying formaldehyde–lignin mass ratios (F/L), where d_P is the pore diameter and V the relative pore volume

Figure 6. SEM image of the lignin–formaldehyde aerogel (F/L 2) before (left) and after (right) carbonization

Figure 7. TGA curve (relative weight Rw plotted against temperature T) and the first derivative of the lignin–formaldehyde aerogel (F/L 1) after drying with supercritical CO_2.

Data availability statement

Data availability statement Data will be made available upon request to the corresponding author at [email protected]. https://www.wood-kplus.at/en.