Yields of hydrogen-rich gaseous products via pyrolysis from selected biomass samples

Future energy technology will utilize hydrogen with an increasing trend in steady, as well as unsteady, combustion processes. Hydrogen is produced from fossil fuels, hydrocarbon polymers, biomass, and water by electrolysis and from biological process by photoliticaly or thermolysis. Hydrogen is produced from solid waste by pyrolysis. In this study, three different biomass samples were subjected to direct-and catalytic pyrolysis in order to obtain hydrogen-rich gaseous products at desired temperatures. The samples, both untreated and impregnated with catalyst, were pyrolysed at 770, 925, 975 and 1025 K temperatures. The total volume and the yield of gas from both pyrolysis were found to increase with increasing temperature. The largest hydrogen-rich gas yield were obtained from olive husk, cotton cocoon shell, and tea waste using about 13% ZnCl2 as catalyst at about 1025 K temperature were 70.3, 59.9, and 60.3%, respectively. In general, in the pyrolysis of biomass, the yield of hydrogen-rich gaseous product increases with ZnCl2 catalyst, but the yield of pyrolytic gas decreased in spite of increasing the yield of charcoal and liquid products. The effect of K2CO3 and Na2CO3 as catalysts on pyrolysis depends on the biomass species. The catalytic effect of Na2CO3 was greater than that of K2CO3 for the cotton cocoon shell and tea waste, but the catalytic effect of K2CO3 was greater for the olive husk. (C) 2001 Elsevier Science Ltd. All rights reserved.