Low-pressure hydrothermal processing of mixed polyolefin wastes into clean fuels

The amount of polyolefin waste, which is 63% of the total plastic waste, has grown exponentially over the past six decades. Its degradation products pose a serious threat to ecosystems and human health. Polyolefins can be converted to clean oils or fuels by using the supercritical water liquefaction (SWL) method at high pressures (>23 MPa), which require high capital and energy costs. A new low-pressure (-2 MPa) hydrothermal processing (LP-HTP) method is developed to convert polyolefin waste with 50% or more polypropylene into oils with 87% yield at 450 ?C and 45 min. The oils, which are C4 to C25 hydrocarbons, can be distilled into clean gasoline and ultra-low sulfur diesel. With this method, up to 190 million tons of fuels can be produced annually from polyolefin waste, resulting in savings of 92% of the energy and 71% of the GHG emissions compared to conventional methods for producing fuels.

Automated summary

A new low-pressure hydrothermal processing method has been developed to convert polyolefin waste into clean oils with high yield, which can be further distilled into gasoline and diesel. This method saves a significant amount of energy and reduces greenhouse gas emissions compared to conventional production methods.