Potential use of natural rubber to produce liquid fuels using hydrous pyrolysis - a review

Natural rubber is a tropical plantation crop that mainly consists of the hydrocarbon polyisoprene (cis-1,4-polyisoprene). Rubber can be converted through depolymerization into a liquid, which can be used as fuels or a chemical feedstock. This paper provides information on natural rubber and its alternative sources worldwide. Although we focus on hydrous pyrolysis, we also introduced various depolymerization processes, including pyrolysis, gasification, chemical degradation, catalytic cracking and hydrogenation. Hydrous pyrolysis improves the depolymerization process, such that raw materials can be fed without requiring a drying process. This process can also be conducted at low temperatures, and water can be solely used as the reaction medium and can be easily separated from the oil product. This paper also reviews the role of process parameters such as temperature, rubber to water ratio, reaction time, and type of gases on product quality and quantity. Moreover, this study highlights the environmental and economic feasibility of hydrous pyrolysis.