Biomass as a source of raw materials

May 12, 2009

For the protection of the environment, and because of the limited amount of fossil fuels available, renewable resources, such as specially cultivated plants, wood scraps, and other plant waste, are becoming the focus of considerable attention. Processes such as pyrolysis or liquefaction allow the conversion of biomass into bio-oil, a highly promising renewable source of energy.

A team of German and Chinese scientists led by Johannes A. Lercher at the Technical University of Munich has now developed a new catalytic process to convert components of bio-oil directly into alkanes and methanol. As reported in the journal Angewandte Chemie, the process is based on a "one-pot" reaction catalyzed by a precious metal on a carbon support combined with an inorganic acid.

Bio-oil is an aqueous, acidic, highly oxidized mixture. However, its high oxygen content and instability turn out to have a negative impact: bio-oil cannot be used directly as a . It would, however, be highly interesting as a source of basic raw materials if it were possible to convert it to alkanes. Alkanes, which are also commonly called paraffins, are saturated hydrocarbons; they are among the most important raw materials for chemical industry, and in particular as starting materials for the production of plastics. Furthermore, they are among the primary fuels in the world's economy.

Bio-oil contains a phenolic fraction consisting of compounds with the main framework being an aromatic ring made of six carbon atoms with some hydroxy (-OH) groups attached. With the new process, the phenolic components of bio-oil can be converted with high selectivity to cycloalkanes (ring-shaped alkanes) and methanol. The researchers were able to demonstrate this with various model substances. As catalyst, they used palladium metal on a carbon support, with phosphoric acid as the proton source for the reaction.

The reaction is a "one-pot" reaction, meaning a one-step reaction whose partial reactions (hydrogenation, hydrolysis, and dehydration) occur in the same reactor, with no intermediate work-up. The secret is in the catalyst, which works on all of these different reactions. The end result is a mixture of various alkanes that separates into a second phase, making it easy to separate from the aqueous bio-oil phase. The new process is a practical approach for the direct use of bio-oil for the production of alkanes.

More information: Johannes A. Lercher, Highly Selective Catalytic Conversion of Phenolic Bio-Oil to Alkanes, Angewandte Chemie International Edition 2009, 48, No. 22, 4047-4050, doi: 10.1002/anie.200900404

Source: Wiley

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david_42
not rated yet May 12, 2009
wood scraps?? Whomever is working on this process needs a reality-check. There are no wood scrapes. I live near the largest softwood lumber mill in the USA and everything on a log gets processed and sold. Lumber is one of a dozen products the mill puts out and only the whine of the saws is unused.
Nerdle
not rated yet May 12, 2009
Ok so the wood scraps dont seem like a good idea, but all they need is the bio-oil from any bio-mass. Im sure if you go to any landfills you would find a huge amount of bio-mass just sitting there not being used to its full potential.
Caliban
1 / 5 (1) May 12, 2009
That will probably take care of the "clean green" component of household waste. Now, if we can find a way toconvert food scraps and plastics waste, that would be something to cheer about. Imagine mining the Pacific Ocean Plastics and landfills across the planet.
jerryd
not rated yet Jun 04, 2009

Much better is gasify it to 1500F which then turns to syn gas, H2/CO, which by the FT process turns into any HC you want depending on catalyst, temp and pressure. They use FT now to turn NG into diesel in massive plants called GTL. Google FT and GTL.