Artificial Coal: Facile and Green Production Method via Low-Temperature Hydrothermal Carbonization of Lignocellulose

A new concept is proposed for the production of artificial coal under HTC conditions using Mg(NO3)2 as an oxidant in a short time, which is found to enhance the coalification degree of hydrochar from lignocellulosic materials. Pressure promotes decarboxylation reactions of lignocellulose to form hollow smooth-faced regular spherical particles, avoiding the agglomeration of hydrochar particles. In parallel, oxidation can break down the biopolymer structure to form low-molecular-weight compounds, which is found to be a key step during artificial coal formation. The artificial coal synthesized has a high degree of coalification.