PERFORMANCE OF CNT MODIFIED BY NI WITH RU AS PROMOTER IN HYDROTHERMAL GASIFICATION OF GLUCOSE

Abstract

Supercritical water gasification (SCWG) is a promising way to produce energy from biomass in term of gaseous product. In this study, glucose was gasified in supercritical water in a batch reactor at temperature of 400 °C and pressure of 25 MPa. Nickel supported-single walled carbon nanotube (Ni/SWCNT), Ni/SWCNT promoted with ruthenium (Ru-Ni/SWCNT), and single walled carbon nanotube (SWCNT) were employed to study the effect of each catalyst on gasification product. Concentration of glucose was 5 wt%. Ratio of catalyst to glucose was 3:10 by weight. Reaction time was varied from 15 to 60 min. Energy dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) analysis, and X-ray diffraction (XRD) were used to confirm the catalyst synthesis achievement. After SCWG, gaseous, liquid, and solid (char) products were observed. Ni/SWCNT and Ru-Ni/SWCNT highly increased gas yield when compared to the conditions of SWCNT and non-catalytic gasification. However, hydrogen yield slightly increased with SWCNT. Methane production was also enhanced by adding metal catalysts, which was attributed that water-gas shift reaction and methanation play an important roles in gaseous phase reaction. Interestingly, it was found that an important period of reaction took place in the first 15 min. At this stage, glucose rapidly decomposed into several intermediates including furfural, 5-(hydroxymethyl)furfural, and other liquid products. However, char was rapidly produced with consumption of furfural and 5-(hydroxymethyl)furfural, resulting in a decrease in hydrogen and methane yield with a longer reaction time.