Fourth Patent Awarded to Ron Stites -- Syngas to Ethanol via DME Path

I have recently received notification that the US Patent Office has awarded a fourth patent to me along with three of my former colleagues at Range Fuels.  Patent 8,288,594, “Selective Process for Conversion of Syngas to Ethanol” was awarded on October 16, 2012.  The list of inventors includes:

• Ron Stites
• Shakeel H. Tirmizi
• Jerrod Hohman
• Stephen Deutch

The patent describes a process for converting a mix of hydrogen and carbon monoxide to ethanol.   This mix is often called “syngas.”  This particular method is especially useful for the type of syngas most easily made from bio-mass, coal, cellulose, wastes and etc.  This carbonaceous/carbohydrate materials generally produce a syngas with H2/CO ratios approximating 1 to 1.  The process uses well known or well developed catalytic steps in a unique overall process. 

The first step is making the syngas into Dimethyl Ether (DME) in a single step reaction:

3H₂ + 3CO -> CH₃OCH₃ + CO₂

The second step is adding CO to the DME to make Methyl Acetate:

CO + CH₃OCH₃ -> CH₃COOCH₃  

The final step is the reduction of the Methyl Acetate to make Ethanol and Methanol:

CH₃COOCH₃ +2H₂ -> C₂H₅OH + CH₃OH 

The Ethanol and Methanol are separated by distillation.  The Ethanol is sold and the Methanol can be recycled in a number of ways to make more DME.  Conceptually, the simplest way is to react it back to syngas according to the reaction:

CH₃OH <-> 2H₂ + CO

When all of these reactions are taken together the overall reaction is:

3H₂ + 3CO -> C₂H₅OH + CO₂

The patent goes into to a few nuances on clever ways to recycle the Methanol and re-direct gas flows, but the above reactions give you the gist of what the patent is about.  It is a very clever and low risk way to make bio-mass derived syngas into a very saleable product – high purity Ethanol.  It can be done at a very large scale using catalyst and separation technologies that already exist.  It is one of the more useful ideas that were generated by the research team at Range Fuels.  In fact, the idea is so useful that the patent was actually picked up by a US catalyst company (see the actual patent at:  http://www.uspto.gov/ by searching by patent number).  It is hoped that this company or some of their industrial customers will use this patent to produce Ethanol from bio-mass and other carbonaceous materials such as coal or organic wastes. 

There are many such schemes out there, but this is certainly one of the most likely to succeed at a commercial scale.