A Study on Low Temperature and Pressure Hydrogenation of Cyclopropenoid-Group Containing Non-Edible Oil for Biodiesel Feedstock

One of the potential non-edible biodiesel feedstocks in Indonesia is kapok seed oil (Ceiba pentandra). However, the biodiesel made directly from kapok seed oil will not comply with the requirement of Indonesian Biodiesel Standard, because the oil contains cyclopropenoid group, i.e. a reactive group that easily polymerizes, making the biodiesel viscous and thus could plug the fuel injection nozzle on the diesel engine. The aim of this study is to determine the suitable conditions for low T and P catalytic transfer hydrogenation process to eliminate the cyclopropenoid group in kapok seed oil. Potassium formate (10 M) was used as a hydrogen donor solution and the catalyst was a 5%- palladium on carbon (5%-Pd/C) utilized at a level of 0,5%-mass to oil. The concentrations of cyclopropenoid group at the beginning and the end of the hydrogenation were determined titrimetrically using Durbetaki reagent. The best condition for catalytic transfer hydrogenation of kapok seed oil found in this study was at 65 °C for 9 hours, which resulted in about 61% decrease of the cyclopropenoid group. Iodine number measurements indicated that the hydrogenation process merely occured on the cyclopropenoid group, because the group was more reactive than the monoenoic/dienoic bonds on the aliphatic fatty acid chains of the oil.