Green synthesis of hierarchical porous carbon prepared from coconut lumber sawdust as Ni-based catalyst support for hydrotreating Callophyllum inophyllum oil

Abstract

In this work, hydrotreating Callophyllum inophyllum oil (CIO) was performed using hierarchical porous carbon (HPC) supported catalyst prepared from a massively produced waste, coconut lumber sawdust (Cocos nucifera L.), using only K2CO3 as activating agent for a green process. Coconut lumber sawdust was carbonized at 700 °C for 2 h to obtain coke as starting material. The produced coke was then activated at various furnace temperature and K2CO3/Coke weight ratio to generate six different types of HPC supports: HPC2-600, HPC2-700, HPC3-600, HPC3-700, HPC4-600, and HPC4-700. Iodine value has shown that HPC prepared at 700 °C h using K2CO3/Coke weight ratio of 3 (HPC3-700) exhibited the best adsorptive capacity, thus, depicting the most promising potential as a hydrotreating catalyst. In the hydrotreatment of CIO at 550 °C for 2 h using 1:300 (catalyst:feed) weight ratio, with a small addition of Ni to the pore (2.76 wt%), Ni/HPC3-700 catalyst, possessing 400.6 m2 g−1 BET surface area and 1.076 mmol g−1 acidity value, was able to produce a satisfying result by yielding over 74 wt% liquid product with 65 wt% hydrocarbon compounds. According to reusability study, although a gradual decrease of deoxygenation effectivity can be reflected through a declining hydrocarbon production, the level of liquid product generated by the catalyst remained consistent after its 3rd use in the hydrotreatment. The use of a low-cost high performing catalyst for hydrotreating a highly available non-edible oil in this study has offered a more sustainable and economical biofuel production with an environmental benefit.