There are a number of problems that seem to be looming, one of which is the climatic effects of the so-called greenhouse gases. Science should be able to address such problems, but the question arises when a discovery is made is, is this a solution to the designated problem, could it be a solution to the designated problem if some further problems can be overcome, or is it simply an interesting observation but essentially irrelevant in terms of solving any of our problems? With the problem of getting funding for science, "relevance" often becomes an issue. Accordingly, funding applications frequently make significant claims as to what their research might achieve, and there are advantages in carrying this over into the subsequent papers. Of course some of these papers may truly herald an opportunity. So, what do you make of the following?
 
Ammonia is an important chemical for fertilizer, and is usually made through the Haber-Bosch process, which involves reacting nitrogen gas with hydrogen under pressure, the hydrogen being made by steam reforming of methane, in turn obtained from natural gas. The oxygen from the steam ends up eventually as carbon dioxide, so it contributes to the greenhouse effect. However, a new process has been claimed (Science, 345: 638 – 640) that involves electrolysis of air and steam in a pressurized molten hydroxide suspension of nano-sized Fe₂O₃, at temperatures of 200 – 250 ^oC. This process results in the conversion of nitrogen to ammonia with an efficiency that is apparently 35% of the applied current, the other 65% resulting in excess hydrogen. Hydrogen would remain a marketable product. The chemistry is interesting. Iron/iron oxide is a catalyst for the Haber-Bosch process, but that process uses pressures considerably higher than would be found in this reaction. That comparison is probably irrelevant, as is shown by ball-milling standard iron oxide, in which case the reaction did not go, so the nano-sizing is important. The question then is, is this a solution to a problem or merely an interesting side-issue? That leaves open the question, how likely is it that this reaction will scale up successfully, and if it does, then run successfully?
 
The first problem that I could see is that the efficiency drops off at higher current, thus the efficiency of one synthesis was >30% at 20 mA, but ~7% at 250 mA. The suggestion was that the conversion is limited by the available area of nano-Fe₂O₃, which may or may not be fixable during scale-up. From the chemical point of view, the nanoparticles were dispersed throughout the solution, but the electron transfer would presumably occur at the electrodes, so that raises the question, exactly what are the nanoparticles doing? The electrodes were nickel, so they should not be a problem for scale-up, but the area might be. The production rates were in the order of 7 x 10^-9 mol NH₃ per second per square centimetre. That would require a very large area to get 1t/hr, which is hardly a rate to get excited about. The requirement for nano-sized  Fe₂O₃ would also worry me because Fe₂O₃ slowly dissolves in hot sodium hydroxide solution to make sodium ferrite. This was not mentioned in the article. On the other hand, they found conditions that stabilized production for six hours. (Actually, it may not be beyond the bounds of possibility that sodium ferrite is the catalyst, as nano-sized Fe₂O₃ might well be more reactive than the bulk oxide. That is yet another aspect that at least needs answering.) Is this possibly a commercial process? My guess is no, at this stage at least, but it does provide an interesting new opportunity for research. If they could get the current density up significantly, then perhaps there is something here.
 
Would that help solve the greenhouse problem? In my view, since this electricity would be the marginal production, no, unless we find a way to make electricity that totally stops the use of fossil fuels to make electricity. Nevertheless, the production of ammonia is required to address the food problem. However, if we really want to do something about global warming through ammonia usage, then a good place to start would be to make nitrogen fertilizers more efficient. A very large amount of such nitrogen finds its way into N₂O, presumably through the decomposition of ammonium nitrite.  Accordingly, there is plenty of work remaining for further research. The question then is, how to fund it? Unfortunately, the scientist's first duty is to obtain funding, which encourages flag waving in papers.

The question I am now posing involves how scientific papers should be presented where the author faces a dilemma. On one hand, the author wants to show something that might lead to more widespread use, but on the other hand, the information might have more general use. The first point is obviously desirable if in fact the use proposed makes sense, but even if it does not it might still make sense while reporting to funding agencies. The second point involves the dissemination of knowledge, and the problem is if it is presented in one way, it may not be seen by others for whom it may be more useful. The huge output of scientific papers means that nobody can read any more than a tiny fraction, and everybody has to have some form of very coarse screening otherwise they never get anything done.
 
These thoughts were started, for me, by a recent paper (Angew. Chem. Int. Ed. 53, 9755 –9760) which claimed to give an interesting approach to biofuel production, but I feel the more interesting aspect of it was the implied underpinning chemistry. The basic process involved three reactions that started with molecules such as furfural and hydroxymethyl furfurals, which are acid degradation products of carbohydrates. Furfural is readily obtained from pentoses because it steam distills out of a reaction in which carbohydrates are acid hydrolysed at higher temperatures, but hydroxymethyl furfural does not do this, and instead it degrades further. It can be isolated, but at a cost, and at only moderate yield. So, before we go much further, this paper will have questionable direct applicability because it involves relatively expensive starting materials that represent only a part of the initial resource.
 
But it is what happens next that is of interest. The authors carry out an aldol condensation of the furfurals with acetone, thus getting C8, C9, C10, C16, etc materials. Furfural gives the furan ring and the unsaturated ketone. These are now reacted at elevated temperatures and pressures with NbOPO₄ in the presence of hydrogen and a Pd catalyst. The interesting part now is that the NbOPO₄ has the ability to pull out the oxygens, including the furfural ring oxygen and the ketonic oxygen (although this may be a dehydration reaction as the carbon-carbon double bond becomes hydrogenated), with the result that we end up with linear hydrocarbons.
 
The niobium phosphate gets a 94% yield of hydrocarbons, whereas aluminium phosphate gets a zero yield of hydrocarbons, while the palladium there catalyses the hydrogenation of the double bonds. Actually, the phosphate is not that important as Nb₂O₅ gives the same yield of hydrocarbons. According to the authors, what happens is that the bulk Nb – O  – Nb groups break, permitting a Nb – O – C  bond to form, and a nearby hydrogen atom can transfer to the carbon atom.
 
The question then is, what use is this to biofuels? Superficially, not that much because the problem of getting furans probably makes this uneconomic. Not only that, but while the C16 hydrocarbons would make excellent diesel, linear C8 hydrocarbons are not at all attractive as fuels, as lying in the petrol range and having an octane number approaching zero makes them undesirable. What I would find more interesting, though, is how this catalytic system would function with lignin, or lignin derived smaller molecules. While lignin polymerization has essentially no pattern, nevertheless many of the linkages occur through C – O – C bonds. If they could be hydrogenated, and the methoxyl groups removed, it might be a breakthrough in biofuel development. The question then is, why did these authors not try their reaction on lignocellulose to see what would happen? Perhaps they did, and perhaps there are more papers coming, but I do not feel that is constructive. We need to see the fewest papers presented consistent with getting all information over, so as to reduce the deluge.