Catalytic oxidative conversion of C/G-type lignin coexisting in Tung nutshells to aromatic aldehydes and acids

Abstract

Catechyl lignin (C-lignin) is a unique and tempting natural biopolymer for producing chemicals or materials due to its homogeneous linear aromatic structure. The Tung nutshell, as an important industrial solid...

Sustainable production of catechol derivatives from waste tung nutshell C/G-type lignin via heterogeneous Cu–NC catalytic oxidation

“…Heterogeneous catalytic oxidative depolymerization of tung nutshell lignin was conducted according to the reported CuCl 2 homogeneous reaction conditions. 41 These supported catalysts were used at 10 wt%, corresponding to metal loadings of 0.2-0.5 wt% based on the mass of the tung nutshell. To examine the heterogeneous catalytic oxidative performance, a variety of nonnoble metal catalysts were screened.…”

“…To better evaluate the catalytic oxidative depolymerization performance, a blank experiment for the HSQC analysis was performed without a catalyst under N 2 atmosphere, which could approximately serve as a control experiment due to the negligible total yield of 6.0 mg g −1 (1.2 wt%) of the catechol derivatives in such conditions These results conrmed that the C/G-type lignin coexisted in tung nutshells, as supported by previous reports. 41 The organosolv lignin (OL) was also investigated (Fig. S3 †).…”

“…The qualitative and quantitative analysis procedures were based on those in our previous report. 41 All the important data were carefully obtained based on repeated experiments.…”

“…Very recently, we found that commercially available CuCl 2 catalyst enabled the oxidative depolymerization of C/G-lignin to catechol derivative aldehydes and acids. 41 However, these results are homogeneous catalytic processes, which makes it hard to effectively separate the catalyst from the aromatic products in a simple way. Metalcontaining nitrogen-doped carbon (M-NC), a common catalyst, has been widely used for the aerobic oxidation of organic molecules as well as lignin.…”