| 1. |
- Gericke, Sabrina Maria, et al.
(författare)
-
In Situ H2 Reduction of Al2O3-Supported Ni- and Mo-Based Catalysts
- 2022
-
Ingår i: Catalysts. - : MDPI. - 2073-4344. ; 12:7
-
Tidskriftsartikel (refereegranskat)abstract
- Nickel (Ni)-promoted Molybdenum (Mo)-based catalysts are used for hydrotreatment processes in the chemical industry where the catalysts are exposed to high-pressure H2 at elevated temperature. In this environment, the catalyst transforms into the active phase, which involves the reduction of the oxide. Here, we report on the first in situ study on the reduction of alumina supported Ni- and Mo-based catalysts in 1 mbar H2 using ambient-pressure X-ray photoelectron spectroscopy (APXPS). The study confirms that mixing Ni and Mo lowers the reduction temperature of both Ni- and Mo-oxide as compared to the monometallic catalysts and shows that the MoO3 reduction starts at a lower temperature than the reduction of NiO in NiMo/Al2O3 catalysts. Additionally, the reduction of Ni and Mo foil was directly compared to the reduction of the Al2O3-supported catalysts and it was observed that the reduction of the supported catalysts is more gradual than the reduction of the foils, indicating a strong interaction between the Ni/Mo and the alumina support. © 2022 by the authors.
|
|
| 2. |
- Li, Kena, et al.
(författare)
-
Maximizing yield of liquid-lignin from membrane filtration retentate of kraft black liquor
- 2021
-
Ingår i: Industrial Crops and Products. - : Elsevier BV. - 0926-6690. ; 169
-
Tidskriftsartikel (refereegranskat)abstract
- Removal of lignin from kraft pulping black liquor has the potential to increase pulp production, and at the same time lignin can serve as raw material for renewable fuels. There are well-known challenges associated with the outtake of lignin from kraft black liquor. Examples of such challenges are acid consumption and effects on the Na/S balance in the pulp mill, which can be decreased by a new process concept combining membrane filtration and liquid-lignin separation. In this study, we investigated the yield of liquid-lignin in separation from kraft black liquor retentate, specifically concerning how it was influenced by the presence of xylose and galactoglucomannan. For example, the liquid lignin yield after carbon dioxide separation decreased from 89.3 % to 85.2 % and 86.1 % with the addition of 20 g/L xylose and galactoglucomannan, respectively. The results showed that the yield of liquid-lignin decreased with an increasing amount of sugar added. Similarly to previous research, our results showed an improvement of liquid-lignin yield associated with a decrease in the content of sugars in cases of heat treatment prior to separation. We suggest a new explanation for the interaction between lignin and hemicellulose, namely that the interactions occur at a molecular level, with lignin in solution, and that these interactions possibly involve the formation of covalent lignin-carbohydrate bonds. This makes the lignin more polar and less prone to form a liquid-lignin phase.
|
|
