1. Literature Survey of Two-Step Methane-syngas-methanol Processes
Group 4
David Bigelow, Sean Coluccio, Luke Rhodes, Peguy Touani
February 5, 2015
CHBE

2. Background CH4 + H2O → 3 H2 + CO CO + 2 H2 → CH3OH
The production of synthesis gas from methane produces three moles of hydrogen gas for every mole of carbon monoxide, while the methanol synthesis consumes only two moles of hydrogen gas per mole of carbon monoxide.

3. Background cont.
To deal with the excess hydrogen, CO2 is injected in the methanol reactor where it forms methanol and water
CO2 + 3 H2 → CH3OH + H2O

4. Reactors and Catalysts
There are two types of reactors used today: adiabatic and isothermal
Carbon monoxide and hydrogen react over a catalyst to produce methanol
Catalyst:
Zn/Cr2O3 at high pressure and temperature with impure syngas
Cu/Zn/Al2O3 are widely use today and is used at lower conditions

5. Step 1: Conversion of Methane to Syngas
Preparation of Synthetic gas typically accounts for 50-75% of the total capital cost of a Gas-to-Liquid (GTL) plant
Steam Reformation (SR) has been used for decades and forms a hydrogen rich syngas
Catalytic Partial Oxidation (CPOX) is a newer technology that oxidizes methane to form syngas

6. Catalytic Partial Oxidation
Steam Reformation
Catalytic Partial Oxidation
Methane is contacted with steam over a heated catalyst at high pressures and temperatures to produce a high hydrogen content syngas
Requires large heat exchangers and a large initial investment
Strict heat balance requirements which makes it hard to control and difficult to scale down to a small size
Methane is reacted with oxygen over a catalyst bed to yield syngas at a 2:1 hydrogen ratio
Operated at moderate pressures ( MPa) which is compatible with downstream processes
Easier to control and manipulate reactor sizing
Newer technology that lacks research in comparison to steam reformation

8. Step 2: Methanol Synthesis from Syngas
CO + 2H2 ↔ CH3OH
The original methanol synthesis process was operated at high temperature and pressure
Methanol is now generally synthesized using a slightly different reaction, which has the addition of CO2 as a reactant
Modern plants will also use the heat produced from the methanol synthesis for the steam reformation reaction

9. Reactors
Two main types of reactors are used today, adiabatic and isothermal
Adiabatic reactors generally use injection of cooled syngas, whether it is fresh or recycled
Isothermal reactors are continuously cooled, though generally from another source, and operate similarly to heat exchangers
Both types of conventional reactors utilize fixed bed catalysts
The Liquid Phase Methanol Synthesis process is used less often and utilizes slurry reactors instead of conventional fixed bed reactors
Adiabatic and isothermal reactors will generally require specific stoichiometric ratio syngas, which may necessitate using the water-gas shift reaction. Multiple passes through the reactor are needed as a single pass is generally unable to convert more than 50% of the syngas.

10. Reactor Examples Linde Isothermal Reactor
Lurgi Methanol Converter (Isothermal)

11. Reactor Examples Cont.
Topsoe Collect, Mix, Distribute Converter (Adiabatic)

12. Reactor Examples Cont. Slurry Reactor
Slurry reactors are able to convert CO rich syngas, and as such increases the potential for converting methanol from coal or biomass

13. Catalysts
The first catalyst used was Zn/Cr2O3 at high pressure and temperature with impure syngas
In 1966 a Cu/Zn/Al2O3 catalyst began seeing use, and allowed operation at much lower conditions
This Cu/Zn/Al2O3 catalyst is still used today, and remains the popular choice for methanol synthesis

14. Conclusion Two step process of: Varying forms of operation
Conversion Methane to Syngas
Methanol Synthesis from Syngas
Varying forms of operation
Most reactors use similar, using small range of catalysts
Preferable for medium to large scale processes

15. References
M. Lyubovsky, S. Roychoudhury, R. LaPierre. “Catalytic partial oxidation of methane to syngas at elevated pressures. Catalysis Letters. Vol. 99, Nos. 3-4, February 2005.
Methanol/Default.htm