Direct conversion of methane into synthesis gas of H2/CO ratio of 2 has been demonstrated using CeO2 as an oxidant at 873–1073 K. The reaction was accelerated in the presence of Pt black (1 wt%). The reduced cerium oxide after the oxidation of methane can be used to convert carbon dioxide into carbon monoxide.

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Aiming to produce functional oligosaccharides such as diD -fructose dianhydrides (DFAs) from inulin in subcritical water (the hot compressed water), the hydrolysis mechanism of inulin was investigated. The hydrolysis of inulin was conducted in carbon dioxide-the hot compressed water (CO 2-HCW) created with a batch-type reactor (temperature: 100 150 , pressure: 3.0 5.0 MPa). The inulin hydrolysate prepared with CO 2-HCW were determined by electrospray ionization mass spectrometry and UV-Vis spectroscopy. The results showed that inulin is hydrolyzed to monosaccharides, disaccharides, fructooligosaccharides , and DFAs with CO 2-HCW. The hydronium ion concentration ([H ϩ ]) formed in CO 2-HCW was approximately estimated 100-fold higher than [H ϩ ] created in the hot compressed water without CO 2. High [H ϩ ] is believed to be one of the factors that contributes to the hydrolysis of inulin Ͻ150. The generation of 5hydroxymethylfurfural (HMF) occurred by intramolecular dehydration of fructose was suppressed due to low temperature process (Ͻ150). CO 2-HCW is one of the means to convert inulin into DFAs while suppressing the generation of HMF.

The hydrolysis of levan using compressed hot water for the production of functional fructooligosaccharides (FOSs) was investigated. Levans from Erwinia herbicola (EH) and Halomonas smyrnensis (HS) were characterized using scanning electron microscopy and light scattering techniques, and hydrolyzed using compressed hot water at four temperatures (120, 140, 160, and 180°C). The hydrolysates were analyzed using high‐performance liquid chromatography and electrospray ionization‐mass spectrometry. Levan HS showed a crystalline morphology, whereas levan EH showed an aggregated structure. Both levans had molar masses on the order of 106 g/mol, but levan EH had a smaller radius of gyration, hydrodynamic radius, and intrinsic viscosity. Levan EH hydrolyzed into FOSs at approximately 120°C, whereas levan HS required a temperature of at least 160°C, possibly because of differences in the degree of branching of the two levans. Both samples were degraded to fructose when treated at 180°C.