Asian lignin was directly depolymerized to phenol-rich oil fraction (lignin-oil) over Pt/C, Pd/C, Ru/C, and Ni/C under supercritical alcohols. Ethanol and Pt/C (E-Pt) proved to be an excellent combination for producing large amounts of lignin-oil (77.4 wt%) with the smallest amount of char (3.7 wt%). Lignin-oil mainly consisting of monomeric phenols and higher molecular phenolic was subjected to several chemical analyses. Elemental analysis indicated that hydrodeoxygenation and hydrogenation primarily occur during lignin depolymerization. 1 H-/2D-HSQC-NMR and GPC analysis revealed that the M w of lignin-oil remarkably lower than that of Asian lignin, which is clear evidence of β-O-4 and β-β bond cleavages. The top four main monomeric phenols in lignin-oil were 4-ethylphenol, guaiacol, 4-ethylguaiacol, and syringol, for which the sum was mostly produced in E-Pt (41.8 mg/g of lignin) with the highest selectivity (38.3%). With increasing catalyst dosage, we observed that excessive catalyst caused side reactions to hinder the production of monomeric phenols.

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We present environmentally friendly brake pads produced with three different types of lignin, soda lignin (SL), sulphuric acid lignin (SAL) and heat-treated SAL (HL), as frictional materials to replace phenol formaldehyde resin (PFR, binder) and cashew nut shell liquid (CNSL, filler) in commercial automobile brake pad. Then the performance characteristics of the lignin-added brake pads were tested and compared using several fundamental tests. The results showed that lignin-added brake pads adhered to the SAE standard (0.25) for friction coefficient, which is the primary contributor to the performance of a braking system. In particular, the replacement of PFR with SL demonstrated a better friction coefficient than did replacement with SAL or HL, reaching up to 0.6. On the other hand, when lignin was substituted for CNSL as filler, HL-added brake pads showed a significant improvement in wear resistance of 0.12 g (dust generation) compared to SL and SAL, which had a resistance of approximately 0.25 g.