Liquefaction of sunflower seed hulls as a biomass waste material and analysis of products

ABSTRACTThe expected future depletion of the reserves of fossil fuels and the increase of environmentalpollution make the investigations of new and renewable energy resources to be veryimportant. Also, substantial increases in oil prices have forced countries to think about othersources. Biomass and biomass waste materials are abundant, inexpensive, renewableresources and they can be converted to liquid, solid and gaseous products. Due to thesereasons, they emerged as attractive alternative energy sources.In this study, the effects of various experimental parameters on the liquefaction yields of abiomass waste material, namely sunflower seed hulls, were investigated. Temperature,pressure, solvent tetralin/(tetralin+ creosote oil) ratio were the parameters whose effects werestudied in detail. The experiments were carried out in a magnetically stirred autoclave of 250ml capacity. Tetralin and creosote oil mixture and hydrogen were used during the experimentsas solvent and gas medium, respectively. The reaction time at reaction conditions was takenas 45 minutes. The oil, asphaltene, preasphaltene and residue fractions of liquefactionproducts were separated by Soxhlet extraction.As a preliminary study, different biomass waste materials (groundnut hulls, pistachio hulls,walnut hulls, sunflower seed hulls) were liquefied, and the waste material with the highestoil+gas yield was chosen to be studied. Thus, the individual effects of temperature, pressureand tetralin/(tetralin+ creosote oil) ratio on the liquefaction of sunflower seed hulls wereinvestigated in the first part of this study. In the second part, the effects of the sameparameters were investigated based on an experimental design work. The experimental designwas done at three levels, and the studied ranges for temperature, pressure, tetralin/(tetralin+creosote oil) ratio were 325-375 oC, 10-30 atm., and 0/1-1/1, respectively. In the third and lastpart, model equations for oil+gas, asphaltene and preasphaltene yields, and for totalconversion were developed, and an optimization study was done.Keywords: Biomass waste material, sunflower seed hulls, liquefaction, experimental design.