Effect of temperature on calorific value of pyrolyzed empty fruit bunch (EFB) derived biochar

Abstract

The residues from the oil palm industry are the main contributors to biomass waste in Malaysia, and these wastes require extra attention with respect to handling. A survey of the literature indicates that most of them are handled with unsatisfactory practices that negatively impact the environment. Therefore, it is very important that they be utilized for more beneficial purposes, particularly in the context of the development of biofuels via pyrolysis technology. Due to its high carbon content, rich in lignin and low cost, empty fruit bunch (EFB) shows potential to be a good precursor for the production of biochar. The pyrolysis temperature greatly affects biochar properties and its potential usage. Many researches work on biochar have been carried out to assess its potential by investigating its characteristics. The most common thermochemical technique to produce biochar is pyrolysis, during which the organic components are decomposed at adjustable temperature in a nitrogen-limited atmosphere. The focus of this study is to identify the effect of temperature (300, 350, 400, 450 and 500 °C) on calorific value of pyrolyzed EFB derived biochar. Eight experimental runs were conducted. The results were completely analyzed by Analysis of Variance (ANOVA). The model was statistically significant. The factor studied which temperature was significant with p-values < 0.0001. The value of R2 was 0.9633 which indicated that the temperature showed high correlation to the calorific value of biochar from EFB pyrolysis process. A quadratic model equation was developed and employed to predict the highest theoretical calorific value. The maximum biochar calorific value was achieved at pyrolysis temperature of 500 °C. Char yield was obtained highest at 300°C around 53.36 wt% and started to decrease as temperature increase. Result of this experiment revealed that the calorific value of biochar increases as the temperature increases while the yield percentage of biochar decreases as the temperature increases. The yield of biochar decreases with temperature because of the secondary tar reactions of the volatiles, such as thermal cracking, that favors the increase of gas yield.