Italian chemists report a clean method to fix CO2 for new fuel oxygenate.

[NNadir]

The article in the ASAP section of the scientific journal Energy and Fuels is not completely explicit on the environmental attractiveness of this process, but it does have implications for the recycling of carbon dioxide.

Note that this fuel, dimethyl carbonate, is not the same as the diesel/natural gas replacement fuel that I frequently talk up, dimethyl ether.

on the environment and human health is probably one of the
main challenges of this century. Clean routes for the manufacture
of the most important chemicals are required, and in this
perspective, the development of chemical processes that can
represent a more environmentally friendly alternative to the
current methods is a priority.

Dimethyl carbonate (DMC) is actually recognized as an
environmentally benign chemical because of its negligible
ecotoxicity and low bioaccumulation and persistence.1-2
An increased use of DMC as a safe substitute for hazardous
chemicals can be predicted: principally as methylating agent
in place of dimethyl sulfate and methyl halides and as a
carbonylation agent in place of phosgene for the production of
polycarbonates and polyurethanes.3-5 Furthermore, as nonaqueous
electrolyte component, it has found application in lithium
rechargeable batteries.6

Additionally, its high oxygen content makes it a promising
candidate to be used as an oxygenated fuel additive,7-8 for
instance to replace the methyl-tert-butyl ether (MTBE).
It is obvious that the potential diffusion of a safe chemical
necessarily implies a clean and safe route for its production.

Among the few still-existing manufacturing processes of DMC considered environmentally compatible, the most interesting are the catalytic oxidative carbonylation of methanol9 and, particularly, the transesterification with methanol of alkylene carbonates, specifically, ethylene or propylene carbonate (EC or PC) obtained by direct synthesis from epoxides and carbon dioxide (CO2). Several papers were written to describe such synthesis processes, and different catalysts were studied.10-12 The transesterification reaction has several advantages. First of all, the mixture of methanol, DMC, alkylene carbonate, and alkylene glycol that is obtained under the equilibrium conditions is neither dangerous nor corrosive. Furthermore, by distillation, it is possible to recover from this blend the DMC-methanol azeotrope, whose composition fits its use as a gasoline or diesel fuel additive...

...nontoxic salts as base catalysts in DMC production via the transesterification reaction. On the basis of their negligible ecotoxicity and basic properties, Na3PO4 and Na2CO3 were selected. A comparison with CH3COOTl, reported in the patent literature as a very efficient and selective base catalyst under the mild conditions for this reaction,19 was also made.

Methanol, as well as certain epoxides are available from biological sources and/or syn gas.

[Syncronaut Seven]

1. Mmmm.. you said transesterification, you know that gets me hot!

Could it be a replacement for the sodium hydroxide I use to transesterfy animal and vegetable fats now?

Currently I mix my own methyl hydroxide, It's nasty stuff, I'd love a safer alternative.

[NNadir]

2. I recently linked a paper here that discussed trisodium phosphate

as a transesterification catalyst for making biodiesel. I don't have the time to find it now.

TSP is less corrosive than "methyl hydroxide" which is made from sodium hydroxide.

[Syncronaut Seven]

3. Thanks! I'll look in to TSP. you did get the pun about

transesterification making me hot, didn't you ;)

Exothermic reaction. :hippie:

[NNadir]

4. Yeah, I got it.

;-)

[struggle4progress]

5. Really? What useful biological sources are you claiming for epoxides,

when you write " ... certain epoxides are available from biological sources ..." ?

Although the epoxides do occur in oxidative metabolism, they are highly reactive and are a likely cause of carcinogenic and mutagenic damage to cells.

Cells have therefore evolved defensive enzymes such as the epoxide hydrolases.

It thus seems unlikely that commercially useful quantities of epoxides could be isolated from biological sources.

[NNadir]

7. You would have to know chemistry for me to explain.

[struggle4progress]

8. Such a clever, clever retort ... eom

[NNadir]

9. Accurate as well I think. Thanks for your vote of support.

[struggle4progress]

10. Can't answer the question? eom

[struggle4progress]

6. A process such as epoxide-CO2 reaction followed by transesterification ..

.. could not possibly represent an important method for recycling CO2.

The C=O bond in CO2 is among the strongest of covalent bonds. Energy is needed to break it, and that energy will not be used with complete efficiency (some being lost as heat) -- so more energy will be required to break the bond than to form it originally. To eliminate significant amounts of CO2 by such a process, significant amounts of energy would be needed.