Cellulose catalyst rewrites rules of attraction


21 December 2010

Chinese researchers have developed a magnetic solid acid catalyst that raises the prospect of efficiently converting biomass cellulose into useful chemicals, such as sugars for biofuel production.

According to the researchers, the catalyst is better than conventional equivalents because it shows good hydrothermal stability and can be recycled - magnetic nanoparticles pull the acid away from the substrate when a magnetic field is applied.

Using biomass as a source of renewable fuel has attracted interest in recent years in response to global climate change and the search for alternatives to fossil fuels. The main component of biomass is cellulose - a polymer comprising many glucose units linked by beta-1,4-glycosidic bonds, with each chain then interconnected by hydrogen bonds. This structure makes cellulose a tough compound to break down. Enzymes or acid catalysts are needed to do the job. But then separating the catalyst from the reaction residue can be energy intensive and costly.

Now, Yao Fu, at the University of Science and Technology of China in Hefei, and colleagues have come up with an answer. Inspired by previous work that showed sulfonic acid functionalised mesoporous silica materials work well as acid catalysts,1 the team designed and synthesised their new sulfonic acid catalyst in the presence of magnetic Fe3O4 nanoparticles, triblock copolymers and hydrogen peroxide.2

Reaction scheme

The magnetic solid acid catalyst improves the hydrolysis of cellulose to form glucose

© ChemSusChem

'By using our new catalyst, we saved an energy-consuming process to separate the solid catalyst and concentrate the glucose solution,' says Fu. The team tested the catalyst by studying the hydrolysis under different conditions of various carbohydrates, including: cellobiose, starch, cellulose and lignocellulose from corn cobs. They found their sulfonic acid effectively hydrolysed 1,4-glycosidic bonds, producing glucose yields of up to 96 per cent from cellobiose, a disaccharide comprising two glucose molecules. However, only 50 per cent yields were obtained from amorphous cellulose. Importantly, the acid could be used repeatedly without deactivation. 

'Developing a heterogeneous catalyst for cellulose hydrolysis has been a goal for many scientists,' says Joseph Binder, who researches biofuel chemistry at the University of California Berkeley, US. He thinks the enhanced separation and stability properties of the new catalyst are an encouraging contribution towards this goal. 'Still, the challenge of achieving high yields of glucose through the action of a solid catalyst on the insoluble cellulose substrate remains to be solved,' he adds. 

Fu acknowledges that further work needs to be done to realise the industrial potential. 'The optimisation of hydrolysis conditions and low cost catalyst synthesis need to be overcome,' he says. But after modifications have been made to the process and reactor, Fu is optimistic that the process of hydrolysis of cellulose using a magnetic acid catalyst can be scaled up to industrial level. 

James Urquhart 

 

Interesting? Spread the word using the 'tools' menu on the left.

References

1. D Margolese et alChem. Mater., 2000, 12, 2448

2. D Lai et alChemSusChem, DOI: 10.1002/cssc.201000300

Also of interest

Two-faced catalyst

Upgrading biomass to gasoline

07 January 2010

Two-faced catalyst to upgrade crude bio-oil into useful fuel


Biofuels

The biofuel future

The chemistry to convert waste into fuels is now being tested at pilot plants around the world. We may have the science, but are governments and industry ready, asks Emma Davies


Bale of straw

Catalyst cracks tough cellulose

13 July 2006

Could straw furnish the fuel of the future?


Related Links

Link icon Comment on this story at the Chemistry World blog
Read other posts and join in the discussion


External links will open in a new browser window