A comparative study on thermal decomposition behavior of biodiesel samples produced from shea butter over micro- and mesoporous ZSM-5 zeolites using different kinetic models Peter Adeniyi Alaba 1 • Yahaya Muhammad Sani 2 • Wan Mohd Ashri Wan Daud 1 Received: 29 November 2015 / Accepted: 25 April 2016 Ó Akade ´miai Kiado ´, Budapest, Hungary 2016 Abstract This study compared the kinetics of biodiesel produced over mesoporous ZSM-5 zeolites (0.3mesoZBio and 0.4mesoZBio) and conventional ZSM-5 zeolites (ZBio). The pyrolysis of each biodiesel was carried out in the presence of nitrogen at different heating rates of 10, 15 and 20 °C min -1 . The reaction order, activation energy (E A ) and frequency factor (A) were computed using four different models. The models are Arrhenius, Coats–Red- fern, Ingraham–Marrier and Differential model. According to the computed average activation energy based on first order, the activation energies of the produced biodiesel are very close. ZBio exhibits the highest E A (86.53 kJ mol -1 ) compared to 0.3mesoZBio and 0.4mesoZBio (84.92 and 83.26 kJ mol -1 , respectively). Therefore, it is tenable to adduce ZBio as the most stable because higher activation energy engenders higher stability. Keywords Kinetic Á Pyrolysis Á Mesoporous ZSM-5 Á Biodiesel Á Shea butter Introduction Demand for sustainable production of biodiesel as an alternative energy source is ever increasing. This is because of their environmental friendliness, acceptable quality of exhaust gasses and similarity to petroleum diesel [1]. This demand arises from the need to minimize the use of fossil fuel by replacement with a suitable alternative energy source that is renewable and sustainable. This effort is being accelerated by depletion of fossil fuel reserve, ever- increasing fuel price and environmental pollution via greenhouse gas (GHG) emission [2]. Therefore, there arises a need to find fuel processing techniques that could help to obtain quality fuel products. Biodiesel is an essential renewable and sustainable energy source of this repute. Shea butter is an extract of shea nut cheaply obtained from sub-Saharan African shea tree (Vitellaria paradoxa). It is an ivory-colored fat with high free fatty acid (FFA) content [3, 4]. The FFA contents are mainly of steric and oleic acid. Shea butter enjoyed wide utilization in confec- tionery and cosmetic industry; however, the use of shea butter in biodiesel production is still under investigation. The previous work on the transformation of shea butter to biodiesel was done via homogeneous catalysis [5–7]. The properties of crude shea butter are presented in Table 1. Pyrolysis kinetics of biodiesel is of vital importance in thermochemical transformation process for energy pro- duction [8]. Pyrolysis is a thermochemical treatment that culminates in decomposition of organic materials at an elevated temperature in an oxygen- or any halogen-free environment [9–11]. As it proceeds, the physical and chemical phases of the materials are transformed irre- versibly. Pyrolysis kinetics helps to model thermochemical conversion of biomass to biodiesel. Pyrolysis breaks the molecules to volatiles and residue. Pyrolysis kinetics is very complex because biofuel decomposition, yield and composition are influenced by many parameters. This includes moisture content, temperature, heating rate, resi- dent time, size biofuel composition and particles [12–14]. Thermogravimetric analysis (TG) is a useful tool for evaluation of thermal decomposition because of its & Wan Mohd Ashri Wan Daud ashri@um.edu.my 1 Department of Chemical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia 2 Department of Chemical Engineering, Ahmadu Bello University, Zaria 870001, Nigeria 123 J Therm Anal Calorim DOI 10.1007/s10973-016-5505-8