The formation of a nanocarbon from lignocellulose with a sea anemone appearance

A filamentous carbon nanomaterial having morphology, elemental compositions and growth conditions similar to those of a sea anemone was formed during pyrolysis of lignocellulose in the presence of water and sodium. We call the material “carbon nano-anemones” (CNAs). Well known carbon nano filamentous materials such as carbon nanotubes find extensive applications in electronics, hydrophobic coatings, catalysis and sensor technology. However, they are inert, non-polar, hydrophobic and surface chemical modification is often necessary before use. CNAs, on the other hand, contain oxygen, are reactive, polar and may be suitable, without modification, for applications e.g., catalysis, sensors. Increasing energy demands, concerns over environmental issues and depletion of fossil resources are amongst the driving forces to use renewable feedstock to meet the future energy needs [1]. Lignocellulosic biomass is a renewable source for fuels [2]. It can be converted to a bio-crude oil via pyrolysis at atmospheric pressure and temperatures around 500 °C [3]. Currently, there is tremendous interest in developing catalysts to make this conversion efficient and to improve the properties of bio-oil to suit application as feedstock in a conventional oil refinery. Formation of solid carbonaceous material is typical and acceptable during pyrolysis reaction as it helps in improving the energy density of the resulting bio-crude oil. However, these carbonaceous materials are usually in the form of char, a low value by-product material. We have recently shown that sodium modified amorphous silica alumina (Na/ASA) catalyst is promising for the pyrolysis conversion of lignocellulosic biomass (Canadian Pinewood) to bio-crude oil having a higher energy content (24 MJ kg−1) than a non-catalytic thermal process (18 MJ kg−1) [4]. During this pyrolysis experiment (450 °C, 1 bar, 20 min), a new type of carbonaceous material having filament-like morphology similar to sea anemones was observed (Fig. 1a and c) (for detailed reaction and catalyst preparation procedures please see Supplementary material). The features of sea anemones are strikingly similar to carbonaceous material observed in the pyrolysis experiment (Fig. 1b and d). For this reason we term them as carbon nano-anemones (CNAs). The anatomy of sea anemones (Fig. 1a and c) contains elongated flexible extensions called tentacles. Carbon nano-anemones have very similar filamentous features (Fig. 1b and d). They have tips at the free end of their structure similar to that observed for sea anemones at the end of their tentacles. Furthermore, similar to sea anemones, CNAs do not have any unique spatial orientation