ALCOHOL SYNTHESIS – Mixed alcohols production from syngas
1. Mixed (C1-C4) alcohols
- Sulfided transition metal catalyst : Cr, Mo, W
- Nanosizing the metal catalyst during synthesis
- Suspending the catalyst in solvents to form a slurry (allows excellent heat management during the thermal operations, and this in turn increases mixed alcohol product yield).
- Asdding sulfur to extended catalyst life
- Contacting the slurry with syngas at 200-325°C and 500-3000 psig
It is desired that ethyl alcohol be a major product constituent, with the yield of methanol at a very small portion of the overall product.
2. Higher aliphatic alcohols (C2 + alcohols)
- passing a gas mixture comprising carbon monoxide and free hydrogen through 1st catalyst zone
- Co and/or Co oxide
- MgO and/or ZnO
- passing the effluent from the first catalyst zone in step (a) through 2nd catalyst zone
- Cu and/or Cu oxide
- ZnO
The formed liquid product (mainly methanol and C2 -C8 aliphatic alcohols) can be condensed and then separated into two or more fractions containing different alcohols. The separation can be carried out by any conventional technique such as fractionated distillation. Generally, a methanol fraction, an ethanol fraction, a C3 -C5 alcohol fraction (useful as additive to gasoline) and a higher alcohol fraction (C5 -C8) are obtained, and can be recovered as separate product streams. Gaseous reaction effluents, mainly unreacted hydrogen and carbon monoxide, can be utilized as fuel or can be recycled to the reactants.
3. Higher alcohols
- Carbon- supported sulfided molybdenum promoted by K, optionally promoted by Co catalyst
4. Alcohol Formation
- Fischer-Tropsch synthesis with precipitated iron catalyst containing alumina and various levels of potassium promoter