Hydrothermal carbon from biomass: a comparison of the local structure from poly- to monosaccharides and pentoses/hexoses

Abstract

Carbon particles are synthesized under hydrothermal conditions using different biomass (glucose, xylose, maltose, sucrose, amylopectin, starch) and biomass derivates (5-hydroxymethyl-furfural-1aldehyde-HMF-and furfural) as carbon sources. Carbons obtained from mono and polysaccharides, hexose and pentose sugars, and from the biomass derivatives, HMF and furfural, are compared from the particle morphology, chemical composition and structural point of view. A clear structural and morphological difference can be observed in carbons from pentoses and hexoses but in the last case, no matter the nature of the hexose sugar, all carbon materials showed astonishing similarities opening the way to the use of renewable biomass in the synthesis of such carbon materials.

Deactivation of sulfonated hydrothermal carbons in the presence of alcohols: Evidences for sulfonic esters formation

“…The spectra of the as-prepared samples ( Figure 3) are in good agreement with the data reported in the literature [40,41]. Three distinct zones can be observed in the spectrum.…”

“…Surface area, determined by nitrogen adsorption isotherms, is always low, around 7 m 2 g −1 for HC, slightly higher than values reported in the literature [18,40], in agreement with the smaller particle size. The microporous volume is also very low, around 0.2 l g −1 .…”

“…Hydrothermal synthesis from carbohydrates leads to carbonaceous materials with relatively high oxygen content [40] (O/C ratio = 0.304, Table 1). Sulfonation produces a 7 significant increase in the oxygen content of the material [18] (O/C ratio = 0.528, Table 1), probably due to oxidation processes taking place besides sulfonation with sulfuric acid.…”

“…Hydrothermal carbons (HC) were prepared from aqueous solutions of glucose, using Hydrothermal carbon (HC) was obtained in the form of nanospheres (300-400 nm diameter, Figure 1), slightly smaller than those reported in analogous materials [40].…”

Chemical, structural and energy properties of hydrochars from microwave-assisted hydrothermal carbonization of glucose

“…The hydrothermal carbonization process involves carbonization and solubilization of organics leading to the formation of tarry substances, which usually contaminate the hydrochars, plugging their pores, and making the apparent BET surface area to be small [39]. Similar results have been reported using the conventional hydrothermal method [9,40]. Thus, surface area and porosity improvement are usually carried out for the hydrochars to fit into specific applications, such as hydrogen or electrical energy storage [33].…”