Corrosion resistant alloys for biologically derived fuel oils: Energy and

[NNadir]

Fuels article.

I am trying to learn more about the properties of biologically derived oils with an eye to considering process and composition of matter issues. In this month's issue of Energy and Fuels (Energy & Fuels 2004, 18, 1291-1301) there is an interesting article studying the corrosion properties of biological oils.

"Fuels produced from renewable resources, such
as forest residues, do not increase the net amount of
carbon dioxide released to the atmosphere. Therefore,
oils obtained by pyrolysis of biomass could help satisfy
the energy demand in an environmentally friendly way.
Biomass, such as bark residue, can be transformed by
pyrolysis to charcoal, oil, and gas. Many research groups
have studied the use of pyrolytic oils, also known as biooils,
as a fuel for burners and gas turbines.1 There are
important differences between bio-oils and petroleumderived
oils. In comparison to petroleum-derived oils,
bio-oils have a lower heating value, a higher oxygen
content, and are much more corrosive.2 It was observed
that, even at low temperatures, bio-oils strongly corrode
aluminum, mild steel, and nickel-based materials,
whereas stainless steel, cobalt-based materials, brass,
and various plastics are much more resistant.3,4"

This gives added insight to the types of problems one might encounter in infrastructure changes.

[amandabeech]

1. Would these corrosive properties alsobe found in biofuels

made from pressed seeds and methanol(?), e.g., biodiesel from soybeans?

How about oil resulting from thermal depolymerization of carbon-carrying waste materials, such as the oil coming out of the TDP plant at the Butterball turkey facility?

[NNadir]

2. Not necessarily.

This paper describes pyrolytic oils obtained from wood pulp which are quite different in composition than soybean oils in chemical composition. The chemistry of the wood pulp oils is described in Energy & Fuels 2004, 18, 704-712. Although fractions of these oils do contain, apparently, some fatty acids, they are very heavy waxes which are methanol insoluble.

The precise chemical nature of these waxes is not given in the paper, but one might imagine, at least from the name, that compounds like Lignoceric acid, a C-24 saturated straight chain acid. The methyl and ethyl esters of lignoceric acid are both waxes with melting points, respectively, of 60 and 57 degrees Centigrade, well above room temperature. (These would probably be suitable for candle manfacture after petroleum no longer exists.)

The oils described here have a high oxygen content, contain many phenolic and polyphenolic compounds, and exhibit low long term stability in the presense of air. The proposed application for their use is in fact in diesel engines, apparently, but not for transportation purposes so much as industrial processes, such as the generation of electricity.

Since these oils are obtained from trees, they constitute more of a byproduct from wood processing than a scalable transportation fuel option.

[phantom power]

3. Sounds like they might corrode an engine cylinder-wall, too

although maybe they wouldn't remain uncombusted in the cylinder long enough to matter.

[NNadir]

4. That was I think the purpose of the first paper, to identify resistant

alloys. The first paper in this thread indicates that it is mostly concerned with storage tanks, and not combustion properties. It's worth noting that all combustion results in some acidic and corrosive gases. Almost all result in the formation of some nitric acid. Petroleum based fuels often add sulfuric acid to the mix.

Again, I think this fuel will have localized use, most likely at the plants where wood pulp or lumber are produced. It need not be used either in diesel engines; it might be used as burner fuel. Of course irrespective of how exactly it is used, the oils in question will still have the major environmental benefit of being carbon neutral, especially where the wood is replaced by planting new trees.