Gasification processes of wood biomass have received attention as an efficient technology for the conversion of biomass into energy. The gas obtained by biomass gasification has wide ranging applications, for example, in gas turbines, in fuel cells, and for the synthesis of chemicals. Generally, very high temperatures of over 1073 K are needed for steam reforming of lignin in the gasification process. However, low-temperature methods for lignin gasification are desirable, because waste heat available from high-temperature processes in industry can be utilized for
energy generation.1
Gasification in supercritical water (Tc ) 647.3 K, Pc ) 22.1 MPa) could be a potential technology to reduce the biomass gasification temperatures1-9 because of high solubility and hydrolysis rates of biomass in supercritical water, leading to minimized mass-transfer limitations of the reactant10-12 and its rinsing effect by washing coke precursors on the active catalyst sites.13 The decomposition behavior of lignin in supercritical water around 673 K was reported in which lignin was converted
to alkylphenols and formaldehyde via hydrolysis14-20 and then the decomposition of alkylphenols to gases...
...The gasification of biomass in supercritical water around 673 K is enhanced by metal catalysts.1-6,22-24 We have reported the order of activity of various catalysts for lignin gasification in supercritical water at 673 K as ruthenium > rhodium > platinum > palladium > nickel.23 Sato et al. conducted the gasification of alkylphenols as model compounds for lignin over several supported metal catalysts in supercritical water at 673 K and reported ruthenium as the most effective catalyst.24...
The report is from the scientific journal
Energy and Fuels Energy & Fuels 2006, 20, 2337-2343
The article reports 100% gasification of lignin, giving a mixture of methane, ethane, propane, butane, hydrogen, carbon monoxide, and carbon dioxide. Carbon dioxide is often a major product, but carbon dioxide obtained from renewable sources can be a useful source of carbon based fuels suitable for use in motor fuels. The cleanest and most convenient of all possible motor fuels is dimethyl ether, DME, which is readily accessible by hydrogenation of carbon dioxide.
Lignin is a by-product of the paper pulping industry. The paper pulping industry is already the primary supplier of renewable electricity, providing a few percent of the world's electrical energy. What is different about this work is that it is gasification, which offers certain advantages, including the ability to manufacture motor fuels.
The most stable catalyst was ruthenium supported on titanium dioxide.