Study on Selective Preparation of Phenolic Products from Lignin over Ru–Ni Bimetallic Catalysts Supported on Modified HY Zeolite

Abstract

The catalytic depolymerization of organic solvent lignin with the prepared catalyst 2.5Ru–10Ni/Al-HY was investigated in a high-pressure reactor. Effects of different catalysts, temperature, time, recyclability for catalyst, and solvents on the catalytic performance were explored. The optimal reaction conditions were reaction time 5 h and temperature 280 °C in ethanol solvent. As a result, the highest yield of phenolic monomers was 20.2 wt %, the yield of solid residue was only 4.8 wt %, and the gas products were CH4, C2H6, and CO mainly. With the increase of cycle times, the catalyst had no obvious deactivation, indicating a unique cycle stability. Through NMR characterization of lignin and depolymerization products, it was found that the signals of the original structures (A, B, and C) in lignin disappeared after reaction. According to the analysis of the reaction path, the depolymerization of lignin mainly included the depolymerization of lignin into reaction intermediates and the formation of phenolic compounds by breaking chemical bonds. This research showed a method for preparing phenolic products by the molecular sieve catalyzed depolymerization of lignin.

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

“…The basic information of the GC-MS is that the inlet temperature is 270 °C, helium is used as the carrier gas, and a DB-5 column (30 m × 250 μm × 0.25 μm) is equipped. The specific conditions are consistent with our previous study …”

“…It is proved that the high temperature is favorable to cleavage of C–C and C–O bonds in lignin, thus promoting the conversion of lignin to monomer . However, the yield of 4-hydroxy-3,5-dimethoxyphenylacetic acid decreased, and the biochar yield increased from 280 to 290 °C, which was ascribed to the fact that too high a temperature is more propitious to product repolymerization. , Accordingly, the 4-hydroxy-3,5-dimethoxyphenylacetic acid reached a maximum yield of 13.52 wt % at 280 °C.…”

“…The specific conditions are consistent with our previous study. 34 The Fourier transform infrared spectrometer of Nicolet IS50-Nicolet Continuum was used to analyze lignin and depolymerization products by the potassium bromide pellet method. The average molecular weights of lignin and liquid-phase products at different reaction times were studied by gel permeation chromatography (GPC) of Agilent 1260.…”

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

“…For the detailed assignment of peak positions in the spectra, refer to the previous literature studies. 54 Figure 9a,c shows the typical structure of eucalyptus lignin. In the aromatic region (δC/δH = 95−140/6.0−8.0 ppm), abundant S′, S, and G structures were detected.…”

Efficient synthesis of 5-hydroxymethylfurfural by MCM-41 modified with multiple acid sites

“…Al-MCM-41/S was prepared by the wet impregnation method. 52,53 A certain amount of MCM-41/S and Al(NO 3 ) 3 $9H 2 O was stirred and mixed aer adding a small amount of distilled water into the beaker. Then, the mixture was treated by ultrasonic oscillation and kept in a static state for 36 h. Next, the mixture was dried in a blast drying oven at 100 °C and calcined in a muffle furnace at 500 °C for 5 h. The resulting solid was obtained and denoted as x%Al-MCM-41/S (x = 2.5, 5, 7.5, 10, 12.5) where x represents the mass fraction of Al in MCM-41/S.…”