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

Abstract

Natural rubber is a tropical plantation crop that mainly consists of hydrocarbon polyisoprene (cis-1,4-polyisoprene). Rubber can be converted through depolymerization into liquid, which can be used as fuels or 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 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.

Waste Tyres Pyrolysis for Obtaining Limonene

“…. The yields of oil (38-78%), gas (10-17%) and solid residues (45-49%) were similar to those obtained by thermal decomposition [51].…”

“…Various attempts have therefore been made to reduce the energy consumption of tyre pyrolysis [27][28][29][30][31]. The required thermal energy can be supplied in several ways, divided into two main categories: conventional (internal-partial combustion of the load, external-electrical resistance or flame [32,33]) and non-conventional (microwave [34][35][36][37][38][39], ultrasonic [40][41][42][43][44][45][46], plasma [47] and supercritical water [48][49][50][51] or carbon dioxide [52,53]).…”

“…A modification of liquid-solid tyre pyrolysis is to replace the oil solvent with water [48][49][50][51] or supercritical carbon dioxide [52,53]. This hydrous pyrolysis performed at high temperatures (250-400 • C) and pressures (4-22 MPa), sometimes self-generated by gaseous products [51], yields the following fractions: water, gas, oil (ca 70%) and solid residue (ca 30%). In water, the thermal degradation of rubber gives greater yields because its supercritical state temperature and dielectric constant are higher than those of CO 2 ( Figure 3), and also because of its nucleophilic character.…”

Genome-Wide Identification and Characterization of MADS-box Family Genes Related to Floral Organ Development and Stress Resistance in Hevea brasiliensis Müll. Arg.

“…Arg.) is the only commercial source of NR because of its high yield and the excellent physical properties of its rubber products [2], and it supplied 92% of the 10.2 million tons of NR consumed worldwide in 2016 [3].…”

Controlled Polymerization of β-Pinadiene: Accessing Unusual Polymer Architectures with Biomass-Derived Monomers

“…Terpenes, which are common plant oils, have been investigated as monomers since the early 20th century, and synthetic polyterpenes have found a myriad of uses (e.g., as tackifiers, adhesives, food packaging materials, and latex substitutes). Pinenes are particularly promising candidates for renewable monomers, given their high natural abundance .…”