Hydrogen generation via supercritical water gasification of lignin using Ni-Co/Mg-Al catalysts

Abstract

Summary In this study, a group of Ni‐Co/Mg‐Al catalysts was prepared for hydrogen production via supercritical water gasification of lignin. The effects of different supports and preparation methods were examined. All catalysts were evaluated under the operation conditions of 650 °C, 26 MPa, and water to biomass mass ratio of 5 in a batch reactor. The Cop.2.6Ni‐5.2Co/2.6Mg‐Al catalyst showed the best performance with highest gas yield (12.9 wt%) and hydrogen yield (2.36 mmol·g−1). The results from catalyst characterization suggest that the properties of this type of catalyst are dependent on multiple factors including support Mg‐Al molar ratio and preparation method, and better coke resistance of the catalyst could be obtained by the preparation method of coprecipitation. Therefore, coprecipitation method should be applied for the preparation of Ni‐Co/Mg‐Al catalysts for hydrogen production via supercritical water gasification of lignin. Copyright © 2017 John Wiley & Sons, Ltd.

Highly efficient hydrolysis of magnetic milled powder from waste aluminum (Al) cans with low‐concentrated alkaline solution for hydrogen generation

“…Many studies have been carried out to eliminate or to ruin the protective layer to improve the Al reactivity and achieve continuous hydrogen production. One way is to prepare Al alloys with another particular metal such as Ga, Sn, In, Li, and Bi, to obtain higher activities in hydrolysis . But the cost of this method is significantly increased due to the addition of these particular precious metals.…”

“…One way is to prepare Al alloys with another particular metal such as Ga, Sn, In, Li, and Bi, to obtain higher activities in hydrolysis. 4,[19][20][21][22][23] But the cost of this method is significantly increased due to the addition of these particular precious metals. Another way is using hydroxide ions (OH − ) in alkaline solutions to etch the Al 2 O 3 surface during the H 2 production.…”

Comparative evaluation for catalytic gasification of petroleum coke and asphaltene in subcritical and supercritical water

“…There are several reports suggesting the suitability of Ni catalyst in SCW gasification of biomass and other organic wastes [27,28,[55][56][57][58] . Nickel has the tendency to efficiently cleave C-C, C-H, C-O and O-H bonds in highly recalcitrant compounds such as lignin, tars, humic acid and sewage sludge as well as long-chain oxygenated compounds into permanent gases [27,28,58,59] . Compared to other noble metals, the catalytic performance of Ni is substantially higher for H 2 and CH 4 production through hydrogenation and methanation reactions, respectively [23,52,53,55] .…”

Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

“…Nevertheless, compared with homogeneous alkali catalysis [242], heterogeneous catalysts based on transition and noble metals have advantages. Ni-Co/Mg-Al catalysts have been evaluated and have demonstrated high flexibility and potential for gasification [243], while noble metals showed higher activity for the gasification, following this order: Ru > Rh > Pt > Pd > Ni [244][245][246][247]. All the component technologies needed for the production of biofuels or chemicals through gasification at a biorefinery are either already commercially used or are undergoing pilot-scale demonstrations ( Figure 6) and the corresponding technical and economic models have been developed for the simulation and evaluation of the complete process [248][249][250].…”