The critical problem arises from the fossil fuels which has stimulated recent interests in alternative sources for petroleum-based fuel. An alternative fuel should be technically feasible, readily available, environment acceptable and techno-economically competitive. The new generation of renewable fuel is known as green diesel. Green diesel is composed of long chain hydrocarbons that can be prepared from DO (deoxygenation) of palm oil. The feedstock used for the production of green diesel mainly comes from edible vegetable oil which is highly available in most of the countries around the world. However, the compotation between food and fuel economies towards the same oil resources may bring global imbalance to the food supply and demand market. The focus on this research is to produce green diesel using edible feedstock via heterogeneous catalysed DO reaction.

Green diesel or known as the hydrocarbons (alkane and alkene) is a renewable and globally friendly biofuel which generally was derived from the triglycerides or fatty acids. The sustainability of the green diesel always concerned the cost of the production, energy supply and demand (net energy balance), the sustainability of more significant crops production or feedstock supply, acceptance of the country and economic stability. Above all, the lack of the petroleum products, the increase in fuel efficiency and affordable by the public are significant reasons for the green diesel to become one of the most important energy supplies for our future The review found important research areas to be reduction in cost of production and maintenance, improvement in fuel quality and improvement in the environmental benefit from using green diesel. With regard to cost reduction, experiments have been conducted on use of low cost catalysts, waste products as feedstocks and H2-free reaction atmosphere. Fuel quality improvement studies have proposed new catalysts, reaction pathways and conditions to improve hydrocarbon selectivity and fuel stability. Future studies must specifically focus on commercial feasibility of the use of waste materials as feedstocks, heterogeneous catalysts, improvement in reaction pathways to production green diesel and similar other concerns. This article covers the catalysis for deoxygenation, the factor influencing the deoxygenation process and the recent progress of deoxygenation.