Dual-benefit flash pyrolysis for valorizing carbonaceous wastes into high-calorific syngas (94.7 vol% combustibles) and battery anodes

Abstract

Traditional low-temperature slow pyrolysis (LTSP) is inefficient and constrained by low temperatures (300–1000 °C) and prolonged durations, leading to poor kinetics and high energy demand. This work demonstrates an innovative in situ Joule heating technology to achieve ultra-high-temperature flash pyrolysis (UHTFP) at over 3000 °C in approximately one second. This method ensures complete pyrolysis, resulting in enhanced product purity, efficiency, and yield compared with LTSP. The versatility of UHTFP is highlighted by its exceptional product selectivity: the pyrolysis of anthracite yields a hydrogen-rich gas (up to 83.7% H₂), while bituminous coal is efficiently converted into a premium, high-calorific syngas, with combustible monomers (H₂, CO, and CH₄) constituting an impressive 94.7 vol% of the product gas. Molecular dynamics simulations show that the ultra-high-temperature system in a non-equilibrium state can generate numerous free radicals, causing the carbon atoms to be condensed into flash graphene and the heteroatoms to be fragmented into small gas molecules. Moreover, the obtained flash graphene can be used as the negative electrode of lithium-ion batteries, exhibiting a specific capacity of 326.83 mAh g⁻¹. The UHTFP technology is versatile, scalable and capable of swiftly processing materials, such as coal, biomass, and waste plastics, offering significant economic and environmental advantages for chemical and energy production.