Integrating lignin valorization and bio-ethanol production: on the role of Ni-Al₂O₃catalyst pellets during lignin-first fractionation

Abstract

Elucidation of the catalyst role during reductive catalytic fractionation, enabling the integration of lignin valorization and bio-ethanol production.

A Bibliometric Study of Scientific Publications regarding Hemicellulose Valorization during the 2000–2016 Period: Identification of Alternatives and Hot Topics

“…Nevertheless, in some cases, the selected conditions defined an alternative scenario characterized by the retention in the residual pulp of the hemicellulosic fraction [134]. In order to further exploit these processes, a clear understanding of the catalyst's role in the fractionation is required for optimal reactor designs and scale-up initiatives [135].…”

“…The most practical approach proposes the introduction of the pentose-utilizing capability into efficient ethanol producers such as S. cerevisiae and Z. mobilis [135,188,189]. The introduction of xylose isomerases that function well in other xylose-fermenting yeasts is the preferred solution to overcome the limitations caused by xylose to these host organisms [190,191].…”

Fractionation of Lignocellulosic Biomass over Core–Shell Ni@Al2O3 Catalysts with Formic Acid as a Cocatalyst and Hydrogen Source

“…First, owing to their much lower prices and susceptibility to magnetic separation, Ni‐based catalysts have clear advantages over noble‐metal‐based catalysts –. Previously, commercially available Ni catalysts (e.g., Raney Ni,– 21 wt % Ni/Al 2 O 3 ) and conventional Ni‐supported catalysts (e.g., 11 wt % Ni/activated carbon) have been investigated in the RCF reaction. Although these Ni‐based catalysts achieved excellent RCF results, the relationship between catalyst properties and RCF performance is not yet clear.…”

“…Are there any design criteria for Ni‐based catalysts that can be tuned to achieve a high degree of delignification, and to produce high‐purity pulp and a high yield of LDPMs? Secondly, when Ni‐based catalysts were used, a high yield of LDPMs was achieved in the presence of a sufficient quantity of external molecular hydrogen . Owing to the fact that 96 % of hydrogen is produced by steam reforming of fossil fuels, and to the high cost of hydrogen associated with its production, handling, storage, and transportation, it is beneficial to develop an RCF process that is not dependent on external hydrogen, and which still achieves a high yield of LDPMs and high‐purity pulp.…”

“…In contrast, under 2 MPa H 2 , and a mixed methanol/water solvent, a different type of phenolic monomers, 4‐ n ‐propanol guaiacol (POH−G, 3 ) and 4‐ n ‐propanol syringol (POH−S, 6 ), were produced in a 29 wt % yield (Path III, Figure ) . When birch wood lignin was converted over Ru/C or Ni/Al 2 O 3 in methanol at 250 °C and 3 MPa H 2 for 6 h, P−G ( 1 ) and P−S ( 4 ) were the main products (Path I), whereas when a Pd/C catalyst was used, under identical reaction conditions, POH−G ( 3 ) and POH−S ( 6 ) were the main products (Path III) . However, 4‐ n ‐propenyl guaiacol (P=G, 2 ) and 4‐ n ‐propenyl syringol (P=S, 5 ) were the principal products when birch wood was converted over Pd/C in a mixture of ethanol and water at 195 °C for 1 h under an inert atmosphere (Path II) .…”