Issue 14, 2023

From liquid to solid-state, solvent-free oxidative ammonolysis of lignins – an easy, alternative approach to generate “N-lignins”

Abstract

A new chemical modification protocol to generate N-lignins is presented, based on Indulin AT and Mg2+-lignosulfonate. The already known ammonoxidation reaction in liquid phase was used as a starting point and stepwise optimised towards a full solid-state approach. The “classical” liquid ammonoxidation products, the transition products from the optimization trials, as well as the “solid-state” products were comprehensively analysed and compared to the literature. The N-lignins obtained with the conventional ammonoxidation protocol showed the same properties as reported. Their molar mass distributions and the hydroxy group contents, hitherto not accessible due to solubility problems, were measured according to a recently reported protocol. N-Indulin showed an N-content up to 11 wt% and N-lignosulfonate up to 16 wt%. The transition experiments from liquid to solid-state gave insights into the influence of chemical components and reaction conditions. The use of a single chemical, the urea-hydrogen peroxide complex (UHP, “carbamide peroxide”), was sufficient to generate N-lignins with satisfying N-content. This chemical acts both as an N-source and as the oxidant. Following the optimization, a series of solid-state ammonoxidation tests were carried out. High N-contents of 10% in the case of Indulin and 11% in the case of lignosulfonate were obtained. By varying the ratio of UHP to lignin, the N-content can be controlled. Structural analysis showed that the N is organically bound to the lignin, similar to the “classical” ammonoxidation products obtained under homogeneous conditions. Overall, a new ammonoxidation protocol was developed which does not require an external gas supply nor liquids or dissolved reactants. This opens the possibility for carrying out the lignin modification in closed continuous reactor systems, such as extruders. The new, facile solid-state protocol will hopefully help N-lignins to find more consideration as a fertilizing material and in soil-improving materials.

Graphical abstract: From liquid to solid-state, solvent-free oxidative ammonolysis of lignins – an easy, alternative approach to generate “N-lignins”

Supplementary files

Article information

Article type
Paper
Submitted
01 feb 2023
Accepted
12 mrt 2023
First published
23 mrt 2023
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2023,13, 9479-9490

From liquid to solid-state, solvent-free oxidative ammonolysis of lignins – an easy, alternative approach to generate “N-lignins”

G. K. Wurzer, M. Bacher, O. Musl, N. Kohlhuber, I. Sulaeva, T. Kelz, K. Fackler, R. H. Bischof, H. Hettegger, A. Potthast and T. Rosenau, RSC Adv., 2023, 13, 9479 DOI: 10.1039/D3RA00691C

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements