Transition metal salts were employed as the catalysts to improve the selective degradation of the a-O-4 lignin model compound (benzyl phenyl ether (BPE)) in the solvothermal system. The results concluded that most of the transition metal salts could enhance BPE degradation. Among which, NiSO 4 $6H 2 O exhibited the highest performance on BPE degradation (90.8%) for 5 h and phenol selectivity (53%) for 4 h at 200 C. In addition, the GC-MS analysis indicated that the intermediates during BPE degradation included a series of aromatic compounds, such as phenol, benzyl methyl ether and benzyl alcohol. Furthermore, the mechanisms for BPE degradation and phenol selectivity in the NiSO 4 $6H 2 O system involved the synergetic effects between the acid catalysis and coordination catalysis, which caused the effective and selective cleavage of the C-O bonds.Fig. 3 (a) Effect of reaction time on BPE degradation; (b) the hydrogen ion concentration during the process. (c) X-ray diffraction pattern for recovered catalysts. Condition: 300 mg BPE, 1.4 mmol NiSO 4 $6H 2 O, 20 mL methanol, 200 C. 3016 | RSC Adv., 2020, 10, 3013-3019 This journal is

Background Recently, it was full of challenges to realize the mild and directional oxidative depolymerization of lignin at room temperature and pressure. The sinocalamus oldhami alkali lignin (SOAL) was depolymerized into aromatic aldehydes by cooperating LaFe0.9Ni0.1O3 (LFNO-0.1) with sodium persulfate (PDS) under visible light irradiation. Result Under the best conditions of reaction time of 105 min, catalyst dosage of 0.25 g, sodium persulfate of 0.15 g, 80% of lignin was converted and the yield of monomer compounds was up to 2.97 mg/g. In addition, the yield of p-hydroxybenzaldehyde was 1.86 mg/g respectively. And, the selectivity of p-hydroxybenzaldehyde reached about 63% in the monomer product. The effect sequence of factors in the system were as follows: holes > 1O2 > SO4−· > O2−· > ·OH, which could lead to the cleavage of the benzene ring, C-C, C–O, C-H bonds in the internal structure of lignin. Conclusion The study found that LFNO-0.1/PDS played a synergistic role in the SOAL depolymerization. The study was beneficial for mild depolymerization of lignin and conform carbon peaking and carbon neutrality goals.