Metal-catalyst-free gas-phase synthesis of longchain hydrocarbons

Development of sustainable processes for hydrocarbons synthesis is a fundamental challenge
in chemistry since these are of unquestionable importance for the production of many
essential synthetic chemicals, materials and carbon-based fuels. Current industrial processes
rely on non-abundant metal catalysts, temperatures of hundreds of Celsius and pressures of
tens of bars. We propose an alternative gas phase process under mild reaction conditions
using only atomic carbon, molecular hydrogen and an inert carrier gas. We demonstrate that
the presence of CH2 and H radicals leads to efficient C-C chain growth, producing micronlength
fibres of unbranched alkanes with an average length distribution between C23-C33. Abinitio
calculations uncover a thermodynamically favourable methylene coupling process on
the surface of carbonaceous nanoparticles, which is kinematically facilitated by a trap-andrelease
mechanism of the reactants and nanoparticles that is confirmed by a steady
incompressible flow simulation. This work could lead to future alternative sustainable
synthetic routes to critical alkane-based chemicals or fuels.