Experimental investigation of steam-air gasification of Cymbopogon citratus using Ni/dolomite/CeO2/K2CO3 as catalyst in a dual stage reactor for syngas and hydrogen production

Abstract

Steam-air gasification of Cymbopogon citratus was carried out to produce syngas and hydrogen in two reactors (fluidized bed reactor and a flow entrained reactor) heated at 600–1000 °C using Ni/Dolomite/CeO2/K2CO3 catalyst and equal/different steam to biomass ratios (SBRs). The steam-air flow rate was fixed at 4 g/min and 40% v/v. The gasification temperature influenced the overall hydrogen and syngas yield. At a fixed equivalent ratio (ER) of 0.27 and varying SBR, the hydrogen and syngas yield increased. At higher ERs, the heating value of other gaseous products, syngas, total gas flow rate and hydrogen decreased. The results also suggest that, at a temperature of 1000 °C and ER of 0.27, an SBR of 2 gave a maximum yield of 81.01 gH2/kg biomass. At ER = 0.27, the estimated vol% hydrogen and syngas are 78.95 and 58.67 vol%, thus implying that the syngas yield, can serve as precursor for hydrogen production. The results actually affirm the essentiality of ER as a good design parameter for steam-air gasification-reactors. In addition, at higher temperatures, a large amount of steam needs be consumed per unit mass of the biomass in order to convert the residual char to CH4, H2, CO and CO2.