Larix Sibirica Arabinogalactan Hydrolysis over Zr-SBA-15; Depolymerization Insight

Abstract

Arabinogalactan depolymerization over solid Zr-containing SBA-15-based catalyst was studied via HPLC, GPC, and theoretical modeling. Arabinogalactans (AG) are hemicelluloses mainly present in larch wood species, which can be extracted on an industrial scale. The application of solid acid catalysts in the processes of hemicellulose conversion can exclude serious drawbacks such as equipment corrosion, etc. Characterization of 5%Zr-SBA-15 confirmed the successful formation of the mesoporous structure inherent to SBA-15 with fine Zr distribution and strong acidic properties (XRD, XPS, FTIR, рНpzc). Carrying out the process at 130 °C allowed us to achieve total products yield of up to 59 wt.%, which is represented mainly by galactose (51 wt.%) and minor (less than 9 wt.%) presence of arabinose, furfural, 5-HMF, and levulinic acid. The temperature increases up to 150 °C resulted in a total product yield drop down to 37 wt.%, making temperature elevation above 130 °C obsolete. According to the theoretical investigations, arabinogalactan depolymerization follows the primary cleavage of the β(1→3) bonds between the D-galactose units of the main chain, which is also confirmed by GPC.

Chemical Processing of Agriculture Wastes Into Vanillin, Pulp and Glucose

“…To study the molecular weight distribution of hydrolysis products, an Agilent 1260 Infinity II Multi-Detector GPC/SEC System with a refractometric detector and two Agilent PL aquagel-OH columns was used. The eluent was 0.1 M NaNO3 with the addition of 0.25 g/L NaN3, 1 mL/min, with an injection volume of 100 µL [29]. Sulfuric acid was precipitated by adding CaO and filtered through a 0.45 µm PTFE membrane filter.…”