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Thermocatalytic depolymerization of kraft lignin to guaiacols using HZSM-5 in alkaline water–THF co-solvent: a realistic approach
| Content Provider | Semantic Scholar |
|---|---|
| Author | Raikwar, Deepak Majumdar, Saptarshi Shee, Debaprasad |
| Copyright Year | 2019 |
| Abstract | Lignin is recognized as a renewable and rich source of aromatics, which could be an alternative to fossil fuel-based petrochemicals. However, the development of an efficient catalyst and industrially scalable process for lignin depolymerization remains a challenge. The present work is therefore dedicated towards a one-pot approach for depolymerization of commercial kraft lignin in a batch reactor with higher loading using the water–THF solvent mixture over the HZSM-5 and NaOH catalytic system. Process parameters such as time, temperature, lignin-to-solvent (w/v), water-to-THF (v/v), NaOH-to-lignin (w/w), catalyst-to-lignin (w/w), and Si/Al mole ratios of HZSM5 were chosen carefully and optimized using statistical analysis – response surface methodology (RSM). A significant yield of 61% for a particular single ring aromatic compound (i.e. guaiacols) was obtained under the optimized reaction conditions: reaction time = 2 h, temperature = 533 K, lignin-to-solvent ratio = 0.060 (1 : 16.6), water-to-THF ratio = 0.86 : 1, catalyst-to-lignin ratio = 1 : 6 (0.16), NaOH-to-lignin ratio = 0.1 and Si/Al ratio = 280. Around 77% of lignin was selectively converted to guaiacols (79%) with minimal char formation (7.7%). The Hansen solubility parameter and RSM studies indicate that the obtained results were significantly related to the solubility of lignin and guaiacol at different water–THF ratios. FT-IR and 1H-NMR studies were also performed to correlate the process outcome with the presence of functional groups in identified EtOAc soluble products. A plausible mechanism for catalytic depolymerization of lignin has been proposed considering the product distribution obtained under varying process parameters. |
| Starting Page | 3864 |
| Ending Page | 3881 |
| Page Count | 18 |
| File Format | PDF HTM / HTML |
| DOI | 10.1039/C9GC00593E |
| Volume Number | 21 |
| Alternate Webpage(s) | http://www.rsc.org/suppdata/c9/gc/c9gc00593e/c9gc00593e1.pdf |
| Alternate Webpage(s) | https://doi.org/10.1039/C9GC00593E |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
