Cleavage of Lignin-Derived 4-O-5 Aryl Ethers over Nickel Nanoparticles Supported on Niobic Acid-Activated Carbon Composites

Abstract

Cleavage of lignin-derived 4-O-5 aryl ethers has been conducted over nickel nanoparticles supported on niobic acid-activated carbon composite under mild conditions. The hydrated niobic acid has been successfully supported and well dispersed on activated carbon. Due to the coexisting Bronsted and Lewis acid sites on the hydrated niobic oxide, the Ni/xNbAC catalysts exhibited higher activities for cleavage of C−O ether bonds and dehydration than those of the Ni/AC catalyst. With increasing content of niobic acid, a larger amount of O-free alkane is obtained owing to niobic acid-promoted removal of oxygen from lignin-derived aryl ethers. The cleavage of C−O ether bonds and dehydration of cyclohexanol to cyclohexane are both favored at high temperature. The direct cleavage of the 4-O-5 aryl ether bond can also be achieved under low H 2 pressure, forming phenol and benzene as intermediates, followed by hydrodeoxygenation of phenol to cyclohexane.

Effects of reaction conditions on catalytic hydroconversion of phenethoxybenzene over bifunctional Ni/Hβ

“…According to the previous study, the occurrences of above products are attributed to the cleavage of C–O bond in POB to produce phenol and 2‐phenyleth‐1‐ylium, whereby 2‐phenyleth‐1‐ylium continues to be converted to 2‐PEP or EB. It is noted that phenol is partially converted to CH but EB is not converted to ECH, which may be related to the slower hydrogenation rate of BR in EB under 1 MPa IHP . With increasing IHP from 1 to 4 MPa, POB conversion is significantly promoted, and the yields of CH and ECH increase substantially.…”

Hydrodeoxygenation of Lignin–derived Diaryl Ethers to Aromatics and Alkanes Using Nickel on Zr–doped Niobium Phosphate

“…Cleavage of 4‐O‐5 bond as one of the most abundant C−O bonds in lignin has been investigated by lots of researchers, owing to its challenge of high bond dissociation energy (BDE) of 330 kJ/mol . diaryl ether is usually selected as a typical model compound of 4‐O‐5 linkage.…”

“…diaryl ether is usually selected as a typical model compound of 4‐O‐5 linkage. In order to favor BTX production, the soft hydrogenation is required at the expense of the aromatic‐ring hydrogenation, which can be achieved in a low hydrogen pressure hydrotreating process. In this work, we evaluated and compared the catalytic performance of nickel supported on ZrNb binary phosphate solid acids in HDO of lignin‐derived 4‐O‐5 model compound at mild reaction conditions (180 o C, 0.5 MPa).…”

“…Among the various technologies investigated for utilization processing of lignin‐derived monomers and dimers, catalytic hydrogenolysis and hydrodeoxygenation have emerged as attractive and economically viable option . Until now, most of researches focus on deep hydrodeoxygenation (HDO) of lignin‐derived compounds to produce aromatic ring‐saturated alkanes as liquid fuels at relatively high hydrogen pressure of 3–5 MPa .…”

“…Niobium‐containing oxides, as unique water‐tolerant solid acids, have exhibited excellent activity, selectivity and stability for many acid‐catalyzed reactions in water reaction medium, especially for hydrogenolysis, dehydration and hydrodeoxygenation reactions . Among them, niobium phosphate seems to be a very important water tolerant catalyst, which has been widely used for transformation of cellulose and furan compounds .…”