Selective Conversion of Lignin Catalyzed by Palladium Supported on N-Doped Carbon

Abstract

Highly selective conversion of lignin is essential to enable high-value utilization of lignin. Herein, we have prepared a palladium supported on N-doped carbon catalyst modified by 1,3,5-trimethylbenzene (TMB). The Pd nanoparticles are better dispersed on the TMB-modified catalyst than on the original catalyst. Therefore, the catalyst modified by TMB is more effective than the original catalyst in selectively converting lignin. When the organosolv lignin is catalyzed by 3 wt % Pd/CBFS-26-TMB (1:2) at 280 °C for 5 h, the yield of phenolic acid is 25.71 wt % and the biochar yield is only 4.5 wt %. Significantly, 52.59% of the phenolic acid monomers are 4-hydroxy-3,5-dimethoxyphenylacetic acid with a yield of 13.52 wt %. Thus, the catalyst 3 wt % Pd/CBFS-26-TMB (1:2) can effectively break the C−C and C−O bonds in the β−O−4 structure to convert lignin into 4-hydroxy-3,5dimethoxyphenylacetic acid. We have also discussed the possible mechanism of lignin conversion into main products. This provides an essential approach for the high-value utilization of lignin.

Efficient and biocompatible new palladium-supported boehmite nanoparticles: synthesis, characterization and application in Suzuki–Miura and Mizoroki–Heck coupling reactions

“…35 The peaks in the areas of 39.75, 46.65, 67.85, 82.19 and 87.45 correspond with reflection planes 111, 200, 220, 311 and 222 in the XRD pattern and well show that the palladium zero nanoparticles are stabilized on the boehmite substrate (JCPDS card 46-1043). 36–41 The presence of these peaks in the catalysts used in Heck and Suzuki reactions shows that the palladium in the sample has maintained its neutrality after the catalytic activity. Calculating the size of nanoparticles using Scherer's formula shows that the size of nanoparticles is about 13 nm.…”

Enhancing the performance of heterogeneous palladium based catalysts in the mild reductive depolymerization of soda lignin through addition of a non-noble metal and tuning of the preparation strategy

“…11,12 Within the literature, it has been noted than Pd exhibits significantly less hydrodeoxygenation activity than Ru and Pt, making it a preferred choice for the production of lignin-derived functionalized aromatic compounds, despite its higher cost. 19,20 As a result, Pd based nanoparticle catalysts, supported on various supporting materials such as carbon, 21,22 alumina 23 or zeolites 24,25 have been implemented successfully to depolymerize lignin under mild reductive conditions. 11 Nonetheless, the high cost of Pd inhibits its application as a catalyst within actual industry.…”

Sustainable Production of High-Value Chemicals from Selective Hydrogenolysis of Lignin Catalyzed by Co–Pd Bimetallic Supported on Nitrogen-Doped Carbon Spheres

“…In our previous study, porous polymer-derived nitrogen-doped carbon spheres (NDCS) were obtained by carbonizing 1,3,5-trimethylbenzene-modified polybenzoxazines, and NDCS-loaded Pd catalysts have proved to be effective in the selective conversion of lignin . However, the use of high contents of precious metal Pd increased the cost of the catalyst, and the reaction mechanism was not so clear.…”