Fig 1

(a) Schematic representation of the formation process of the flower-shaped NbPWO support after heat treating in air at 500 ℃. (b) SEM image, (c) the HADDF result and corresponding EDX mapping images and (d, e) TEM images of Pt/NbPWO samples."

Fig 2

(a) XRD pattern of Pt/NbWO samples and PW12 and (b) N2 adsorption isotherms of Pt/NbWO, Pt/NbPO and Pt/NbPWO; (c) NH3-TPD curves of different calcination temperature."

Table 1

Pore size distribution and acid content of different catalysts."

Fig 3

Py-IR spectra of Pt/NbWO, Pt/NbPO and Pt/NbPWO."

Fig 4

H2-TPR profiles of Pt/NbPWO, Pt/NbPO and Pt/NbPWO."

Fig 5

XPS spectra of (a) Pt 4f orbital in NbWO, NbPO and NbPWO. and (b) Nb 3d orbital in Pt/NbWO, Pt/NbPO and Pt/NbPWO."

Fig 6

(a) Reaction results for the hydrogenolysis of alkali lignin over various Pt-loaded catalysts, influence of (b) temperature and (c) H2 pressure over Pt/NbPWO. (a) Reaction conditions: alkali lignin 0.1 g, catalyst 0.05 g, H2O 15 mL, cyclohexane 5 mL, 300 ℃, H2 1.2 MPa, 4 h. (b) Reaction conditions: alkali lignin 0.1 g, catalyst 0.05 g, H2O 15 mL, cyclohexane 5 mL, H2 1.2 MPa, 4 h. (c) Reaction conditions: alkali lignin 0.1 g, catalyst 0.05 g, H2O 15 mL, cyclohexane 5 mL, 300 ℃, 4 h. (d) Main structure of the depolymerized products."

Fig 7

2D-HSQC NMR spectra of alkali lignin (a: side-chain region; c: aromatic region) and depolymerization products at optimized condition (b: side-chain region; d: aromatic region); (A) β-O-4 alkyl-aryl ethers; (B) phenylcoumarans; (C) resinols; (S) syringyl units; (S') oxidized syringyl units; (G) guaiacyl units; (H) P-hydroxyphenyl units and (PB) coumarate."

Fig 8

GPC distribution of depolymerization products."

Table 2

The hydrogenolysis of lignin into aromatic monomers in different condition."

Entry	Substrate	Catalyst	Products (%)								Total yield (%)
			1	2	3	4	5	6	7	Others
1	BOSL	Pt/NbPWO	2.14	1.83	1.77	7.58	5.69	7.87	5.03	3.26	35.17
2	EHL	Pt/NbPWO	1.01	1.07	1.58	2.44	6.83	4.21	3.27	4.90	25.31

Fig 9

2D-HSQC NMR spectra of (a, b) BOSL and (c, d) EHL. (A) β-O-4 alkyl-aryl ethers; (B) phenylcoumarans; (C) resinols; (S) syringyl units; (S') oxidized syringyl units; (G) guaiacyl units; (H) P-hydroxyphenyl units and (PB) coumarate."

Table 3

Structural characteristics of the different lignin by 2D-HSQC method."

Fig 10

(a) The stability of the Pt/NbPWO catalyst for the hydrogenolysis of alkali lignin. Reaction conditions: alkali lignin 0.1 g, catalyst 0.05 g, H2O 15 mL, cyclohexane 5 mL, H2 1.2 MPa, 300 ℃ for 4 h. (b) XRD analysis and (c) NH3-TPD profiles of the fresh and used Pt/NbPWO catalyst."