Catalytic conversion of wastes from the bioethanol production into carbon nanomaterials

This work addressed the production of carbon nanomaterials (CNMs) by catalytic conversion of wastes from the bioethanol industry, in the form of either sugarcane bagasse or corn-derived distillers dried grains with solubles (DDGS). Both bagasse and DDGS were pyrolysed at temperatures in the range of 600–1000 °C. The pyrolyzate gases were then used as CNM growth agents by chemical vapor deposition on stainless steel meshes, serving as both catalysts and substrates. CNM synthesis temperatures of 750–1000 °C were explored, and it was determined that their growth was most pronounced at 1000 °C. The nanomaterials produced from pyrolysis of bagasse were in the form of long, straight, multi-wall nanotubes with smooth walls and axially uniform diameters. Typical lengths were circa 50 μm and diameters were in the range of 20–80 nm. The nanomaterials produced from pyrolysis of DDGS were in the form of long, entangled, rope-like structures with rugged walls, and axially non-uniform diameters. Typical diameters were in the range of 100–300 nm and their lengths were in the tens of microns. This process also produces a bio-syngas byproduct that is enriched in hydrogen.

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► Pyrolyzates of bioethanol production residues were generated in an inert environment.
► Using a low-cost catalyst, the gaseous pyrolyzates were converted into carbon nanomaterials.
► Bagasse pyrolyzates generated MWCNTs, whereas DDGS pyrolyzates generated nano-ropes.
► A hydrogen-enhanced bio-syngas is also generated using the low-cost catalyst.