Abstract
Thermochemical conversion of underutilized lignocellulosic streams such as kraft lignin from the pulp and paper industry has the potential to produce sustainable chemicals and biofuels. We here report a process to continuously convert softwood-based lignoboost lignin to hydrocarbons using a three-step approach: i) liquefaction/dispersion of the lignin in a suitable molten salt, ii) pyrolysis of the liquefied/dispersed lignin in a molten salt mixture (ZnCl2, KCl, and NaCl), to obtain a crude lignin oil and iii) upgrading of the lignin oil using a catalytic hydrotreatment to yield hydrocarbons. Step 1 and 2 were integrated using a twin screw extruder with different heating sections at a scale of 20 g/h lignin input. Besides char, a lignin oil, mainly composed of monomeric phenolics, and propylene were the major products. The highest yield of the latter two products was around 32 wt% (23 wt% crude lignin oil and 9 wt% propylene). The lignin oil was subsequently converted to hydrocarbons using a two-step catalytic hydrotreatment approach (stabilization step using CoMo/Al2O3 catalyst and a further deep hydrotreatment over a NiMo/Al2O3 catalyst). The final liquid product contained less than 0.5 wt% of oxygen and was shown to be rich in (cyclo)alkanes and aromatic hydrocarbons. The carbon yield for the overall conversion of lignin to hydrocarbons was 23 %.
Original language | English |
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Article number | 106813 |
Number of pages | 13 |
Journal | Journal of Analytical and Applied Pyrolysis |
Volume | 183 |
DOIs | |
Publication status | Published - Oct-2024 |
Keywords
- Hydrocarbons
- Hydrotreatment
- Kraft lignin
- Molten salts
- Pyrolysis