High Catalytic Efficiency of Lignin Depolymerization over Low Pd-Zeolite Y Loading at Mild Temperature

Abstract

GRAPHICAL ABSTRACT | High catalytic efficiency of lignin depolymerization over low Pd-zeolite Y loading at mild temperature. This article reported a novel low-temperature process for aromatics production through lignin depolymerization catalyzed by 0.1 wt% Pd-zeolite Y catalyst prepared by a facile method. Under the same reactive condition, the as-prepared Pd-zeolite Y catalysts exhibited much higher catalytic efficiency than zeolite Y or commercial Pd/Al2O3-zeolite composites. The selectivity of the Pd-zeolite Y toward lignin depolymerization was also much higher than the other commercial zeolite-based catalysts. With the presence of hydrogen, aromatics were the predominant products with high yields of phenols and dimers (over 99%). The as-obtained aromatics can be promising feedstock for production of fuels or chemicals for various applications. Results revealed that the Pd-zeolite Y catalyst is a highly active catalyst for the cleavage of lignin interlinkages, especially the C-O-C bonds by hydrogenolysis.

Catalytic Depolymerization of Lignin into Aromatic Monomers over Ru-Ni/TiO2 Catalysts

“…The temperature was maintained for 5 hours before transferring the products to a glass beaker, adding 20 mL of toluene, and stirring for 20 minutes. The toluene phase was subsequently analyzed using gas chromatography-mass spectrometry (GC-MS) [17]. Product selectivity (…”

“…The system was maintained at this temperature for 5 hours before the products were transferred to a glass beaker, adding 20 mL of toluene, and stirred for 20 minutes. The toluene phase was subsequently analyzed using GC-MS [17]. The product selectivity (%) and yield (%) were calculated using Equations ( 1) and ( 2 31.4…”

Elucidating the effect of the physicochemical properties of organosolv lignins on its solubility and reductive catalytic depolymerization

“…Reductive catalytic depolymerization (RCD) or catalytic hydrogenolysis is a promising method because recondensation reactions of the intermediate lignin fragments can be controlled in the presence of hydrogen [27]. The process is usually carried out at 140-350 • C in the presence of H 2 or hydrogen donor solvents (e.g., methanol [28], ethanol [29], formic acid [30]) and a variety of redox metal catalysts (e.g., Pt [31], Pd [32,33], Re [34], Ru [35,36], Ni [37,38], Mo [39,40], Cu [41], Co [42], Fe [43]). The RCD of technical lignin generally results in a lignin oil with lower M w (compared to initial feedstock) containing phenolic monomers in low yields (below 20 wt%), and dimers/oligomers of often unknown chemical composition [44][45][46].…”

2‐step lignin‐first catalytic fractionation with bifunctional Pd/ß‐zeolite catalyst in a flow‐through reactor

“…Additionally, given the well-established effect of transition metal catalysis on increasing monomer yield during lignin-first fractionation a plausible optimization strategy could involve the combination of metal and zeolite catalysis for this reaction. [8,34,35] Even though the use of transition metal catalyst supported on zeolites has been extensively studied for high temperature biomass conversion strategies such as pyrolysis with good results, [36,37] the use of zeolite-supported metal catalysts under lignin-first conditions is a field that remains largely unexplored. Particularly the case of metal supported ß-zeolite for lignin-first has not been investigated, to the best of our knowledge.…”

“…Such information would be key to envision and further optimize a 2‐step fractionation strategy in which the process conditions for lignin solvolysis and zeolite assisted depolymerization/stabilization of lignin liquors are tuned independently. Additionally, given the well‐established effect of transition metal catalysis on increasing monomer yield during lignin‐first fractionation a plausible optimization strategy could involve the combination of metal and zeolite catalysis for this reaction [8,34,35] . Even though the use of transition metal catalyst supported on zeolites has been extensively studied for high temperature biomass conversion strategies such as pyrolysis with good results, [36,37] the use of zeolite‐supported metal catalysts under lignin‐first conditions is a field that remains largely unexplored.…”