Hydrogrn Production By Pyrolysis Of Glycerol With Molten Alkali

Hydrogen is becoming an ideal secondary energy for its high calorific value, pollution-free, non-greenhouse gases emission and other unique advantages. However, most of the raw materials of producing hydrogen are fossil fuels, it will result in environmental pollution in the processes of producing hydrogen. Therefore, using glycerol as a raw material of producing hydrogen becomes a hot topic of current research.Experimental study on the pyrolysis of glycerol for hydrogen production in molten alkali, which was used as the heating and reaction medium, had been carried out in a self-designed reactor. The impact of molten alkali on the distribution of pyrolysis products was discussed. Meanwhile, operation parameters like pyrolysis temperature, carrier gas flow rate, feed rate, the catalyst type as well as the molar ratio of glycerol and water were investigated. The results showed that components like CO and CO2in pyrolysis gas were absorbed by molten alkali, so there were more than90%volume fraction of H2and a small amount of CH4in product gas. Feed method which could ensure glycerol to full contact with the molten alkali, could significantly reduce the coke and dehydration reactions, and enhance the yield of hydrogen. High ratio of molten alkali and glycerol was also beneficial to the yield of hydrogen. In comparison to carrier gas flow rate and feed rate, the change of pyrolysis temperature had significant effect on hydrogen yield, the yield of hydrogen could reach4.82mol H2/mol of glycerol, which was68.9%of the theoretical yield, when the pyrolysis temperature was425℃, the carrier gas flow rate was100L/h, and the feed rate was4.5g/min.In this paper, the components of the crude glycerol were identified. Results showed that the components of crude glycerol were complex, mainly included glycerol, C17H34O2, C19H34O2and C19H36O2. Molten alkali had scission ability to the C-O bond.In this paper, cracking characteristics of crude glycerol and the effect of sodium hydroxide were analyzed with TG. Results showed that the cracking process of crude glycerol was divided into three stages. Sodium hydroxide could unify the first and the second weight loss peak, and the cracking stages were reduced into two.