Researchers have developed a new catalyst that directly converts cellulose, the most common form of biomass, into ethylene glycol, an important intermediate product for the chemical industry.
Currently, biomass is mainly used in the form of starch, which is degraded to make sugars and then fermented to make ethanol. It would be cheaper to use cellulose, which is the main component of plant cell walls and thus the most plentiful organic compound on Earth.
At the moment, cellulose is mainly processed by fermentation. However, splitting cellulose into its individual sugar components, which can then be fermented, is a slow and cost-intensive process. Hence, the direct conversion of cellulose into useful organic compounds is an attractive alternative.
Initial reactions using various noble-metal catalysts have been developed. Their disadvantage is that large amounts of expensive metal are needed to break down the cellulose and on an industrial scale these processes are not economical.
So a less costly and more effective catalyst needs to be developed. And that’s exactly what a team led by Tao Zhang at the Dalian Institute of Chemical Physics in China and Jingguang Chen at the University of Delaware has done.
Their catalyst is made of tungsten carbide deposited on a carbon support. Small amounts of nickel improve the efficiency and selectivity of the catalyst system: a synergetic effect between the nickel and tungsten carbide not only allows 100 per cent conversion of cellulose, but also increases the proportion of ethylene glycol in the resulting mixture of polyalcohols to 61 per cent.
Ethylene glycol is an important intermediate in the chemical industry. For example, in the plastics industry it is needed for the production of polyester fibres and resins, and in the automobile industry it is used as antifreeze.
The development was first reported in the journal Angewandte Chemie.