In-situ Mass Spectroscopic Analysis of Glucose Decomposition under Hydrothermal Condition: Quantitative Analysis for Reaction Kinetics

The utilization of renewable energy resources is desirable owing to several issues, including the depletion of petroleum resources and global warming1). Among many kinds of renewable resources, marine biomass (macroalgae) could be a promising feedstock for bioproduct and biofuel production2),3). However, appropriate pretreatment is needed prior to its effective utilization. Owing to the high water content of macroalgae, pretreatment under hydrothermal conditions is more favorable. This is because, during the hydrothermal process, water is used as a reaction medium, and thus the drying of feedstock prior to the pretreatment is unnecessary. Furthermore, it was reported in previous studies that hydrothermal pretreatment employed a simple process and was economical4),5). In order to propose a complete reaction pathway for biomass, detailed information of its decomposition products are required. Previously, it was reported that levoglucosan is the main decomposition product of biomass during fast pyrolysis, whose analysis was performed by gas chromatography/mass spectrometry (GC/ MS)6)~10). However, this analysis is only suitable for volatile products and thermally stable compounds. Thus, the quantification of monomeric unit carbohydrates larger than 0.162 kg/mol without derivatization is apparently difficult11),12). Alternatively, in-situ mass spectroscopic (MS) analysis is another promising method. It has high selectivity and sensitivity, excellent throughput, and requires a small sample amount7),9),13). The quantification of short-life products obtained during the hydrothermal process is also possible by using MS. Generally, biomass is composed of various carbohydrates that exist in the form of monosaccharide or polysaccharides. Among them, glucose has been observed as the main sugar compound in many kinds of biomass. Accordingly, many studies have been conducted on glucose as a model compound of biomass, particularly under hydrothermal conditions14)~21). Our research group also conducted several studies to eluci101 Journal of the Japan Petroleum Institute, 60, (2), 101-109 (2017)