Production of Biodiesel From Peanut Oil Catalysed by Modified Clay

Abstract

Biodiesel production via heterogeneous esterification of peanut oil extracted from peanuts was carried out using clay minerals which are believed to have promising future catalytic properties. The clay samples were calcined (400 oC) and modified with H2SO4 (50%) and NaOH (25%). The calcined and modified clay samples were characterised using FTIR and XRD. Transesterification conditions were; oil to methanol ratio of 1:9, reaction time and temperature, 2 h and 65 °C respectively while the catalyst dosages were 5%, 9% and 15%. The highest conversion observed was 72.24% for the 5% acid modified while the lowest was 19.85% for the 5% alkali-modified clay. The presence of silica is confirmed by the absorption peaks at 1028 cm-1. FTIR peak at 823.23 cm-1 corresponds to Si-O stretching vibration as well as the presence of Al-O bonds. Also, a band at 660 cm-1 in the unmodified clay confirms the presence of Si-O-Si and Si-O-Al bonds respectively. These are typical frequencies for clay samples. The clay samples were also very crystalline as demonstrated by the distinct diffraction patterns of the XRD. These are believed to be good sites for catalytic activities. Important fuel properties of the methyl esters produced from the transesterification process compared well with ASTM D 6751-10 standards. This implies that environmentally benign materials such as clay minerals, which are abundant in availability are good alternatives to the other traditional catalysts employed in this process. These clay materials can thus be harnessed for commercialisation.