Japanese chemists report a scheme to produce hydrogen from biomass.

[NNadir]

As part of the search for alternatives to fossil fuels, which raise atmospheric CO2 levels when burned, attention is increasingly focusing on the potential of biomass for use as a renewable energy resource. Hydrogen, too, is an ideal clean energy source, since its combustion releases only water and no carbon dioxide. For this purpose, gasification of biomass is a promising method. In biomass gasification, the formation of tar is likely to be unfavorable. Although gasification at high temperatures decreases tar formation, the process requires high energy input
that leads to high costs. Moreover, high temperatures may damage the gasification furnace. For these reasons, the process should be operated at low temperature. One of the most promising methods for eliminating tar from the product gas is the catalytic gasification of biomass. Many reports describe the use of catalysts (for example, dolomite); however, carbon deposition on catalysts may cause deactivation.1,2 Tomishige et al. studied the catalytic gasification of cellulose as a model of the conversion of biomass to synthesis gas.3-5 In his study, which used a fluidized bed reactor, they found that Rh catalysts supported on CeO2 or Ce/SiO2 showed high activity for this reaction. Rh/Ce/SiO2 catalysts, in particular, showed catalytic activity for a long period without the formation of tar or char.4,5 Moreover, they reported catalysts to be effective for the gasification of real biomass.6,7

We have investigated hydrogen production by gasification of cellulose over Ni-based catalysts, since Ni has reforming ability and is cheap, and found that Ni/Ce/zeolite catalysts are effective for this reaction.8 We also studied the active site of the Ni catalyst.

The abstract of the article from the ASAP section of Energy and Fuels can be found here: http://pubs.acs.org/cgi-bin/asap.cgi/enfuem/asap/pdf/ef050283m.pdf

It does seem that the catalyst proved to be subject to some carbonization and fouling by tar.

The reactions were run at 500^oC and 600500^oC and therefore are still run at fairly high temperatures.

[skids]

1. Hrm... age of catalysts.

Since you're on a hydrogen kick today, you might want to take a look at catalytic water cracking. The below uses a solar concentrator, but anything that can generate temps of 400C should work for it.

http://www.pureenergysystems.com/news/2004/09/14/6900043_Solar_Hydrogen/

[NNadir]

2. I am already familiar with these systems: GA scientists evaluated 115 of

them.

I in fact happen to have had this link open earlier today that discusses the literature search on this subject: http://www.aspentech.com/publication_files/TP51.pdf

If one scrolls down within this link one can see a bar graph giving the number of papers produced year by year for thermochemical water splitting cycles, the majority of which are now in the public domain as the patents are expired.

1976 seems to have been a banner year, having produced well over 100 such papers.

My qualititive impression is that I am probably the author of about 100 posts here that touched on the subject of such cycles.

The papers I post from Energy and Fuels on the subject of renewable energy are not necessarily endorsed by me. They are research papers that I produce to show research trends.