methane conversion to methanol by platinum catalysts by: sean w. hanley
TRANSCRIPT
Methane Conversion to Methanol by Platinum Catalysts
By: Sean W. Hanley
Cl
Pt
Cl Cl
ClCl
Cl
2-
O
H
H
H
2+
N N
N N
Pt
Cl
Cl
Pt
Cl
Cl
Pt
Cl
Cl
Cl
Cl
Pt
H3N
H3N
Cl
Cl
Cl
Pt
Cl
ClCl
K-
2+
K-
Platinum Catalysts
Cl
Pt
Cl Cl
ClCl
Cl
2-
O
H
H
H
2+
N N
N N
Pt
Cl
Cl
Pt
Cl
Cl
Pt
Cl
Cl
Cl
Cl
Pt
H3N
H3N
Cl
Cl
Platinum (II)
Chloride
(bpyrm)PtCl2
PtCl2
H2PtCl6
(NH3)2PtCl2
All of these catalyst have been studied to see which catalyst has the best percent yield of methanol with the least amount of catalytic death. (bpym)PtCl2 with oleum has been recently found to have 72% yield. This catalyst will be the major catalyst looked at. This reaction has the most hope in industry but also a crucial problem arises. Past catalysts have had 40% yield using mercury which is not environmentally friendly.
Cl
Pt
Cl
ClCl
K-
2+
K-
K2PtCl4
Overall Reactions
CH4 + 2H2SO4 CH3OSO3H 2H2O SO2++(bpyrm)PtCl2
CH3OSO3H H2O H2SO4+ + CH3OH
Overall Reaction
Hydrolysis Reaction
220C
Application Reaction
H2O CO2+ +CH3OH 6H+ + 6e-
Catalytic Interaction
Platinum (II) Platinum (IV)
Catalytic interaction mechanism to form methanol
Activating step of methane
Catalytic Interaction cont.
CH3OSO3H H2O H2SO4+ + CH3OHFinal product then undergoes hydrolysis and turns into methanol
Purposed mechanism for functionalization step
Different Solvent Interactions
• H2SO4 Sulfuric Acid
– Concentrated Sulfuric Acid– Dilute Sulfuric Acid
• HF/SbF5 – Causes Fluorination rather then oxidation of methane
• Methanol and H2O Interacts with catalyst- causing catalytic death
Using Different Catalysts
• (bpym)PtCl2 soluble and good interaction with sulfuric acid
• PtCl2 and PtO2 insoluble in H2O or other organic solvents
• PtCl4, K2PtCl4, and H2PtCl6 soluble but not compatible with sulfuric acid
• This leads us to believe only (bpym)PtCl2 is the only catalyst that works
• Yet Ionic Liquids allow these other catalysts to dissolve readily upon heating
Ionic Liquids (IL)
N
N
+
CH3
1-methylimidazolium
N
HN
+imidazolium
N
N
+
CH3
CH3
1,3-dimethylimidazolium
1-methylpyrazoliumN
NH+
CH3
NH
NH+
Pyrazolium
1,2-dimethylpyrazolium
N
N
CH3
CH3
+
NH +
Pyridinium
1,2,4-trimethylpyrazolium
N
N
CH3
CH3
+
H3C
Ionic Liquids Interactions Cont.
• Better percent yield (Concentration) from the Ionic Liquids then with (bpym)PtCl2 by itself
• Ionic liquids are more water-tolerant• “Green” Chemistry due to low volatility
and good thermal stability
N
N
+
CH3
1-methylimidazolium
Pt
Cl
Cl
Applications• Industry applications to produce natural
gas to liquid products in milder conditions (T < 300oc)
• Use in hydrogen cars to produce a hydrogen yielding reaction from methanol
• Safer fuels
• Environmentally
friendly reaction
Cell Phones
• You need only 2ml of fuel to ensure power for 20 hours operation of an MP3 audio player. Toshiba is actually running field tests with mobile phones at this moment.
Problems Facing Industry
• (bpym)PtCl2 is extremely sensitive to small amounts of water present in the reaction
• Methanol is very hard to extract from the sulfuric acid/ water solution
• There is also severe inhibition from the sulfuric acid/ water solution- causing catalytic death
Future Experiments
• Differing acids may lead to a more accessible way of extracting Methanol as a product
• Using Ionic Liquids to create a higher yield in less concentrated sulfuric acid
• Different Platinum catalysts that are more water-tolerant
Highlights
• (bpym)PtCl2 is a very good catalyst at producing methanol approximately 70% yield
• The problems are that methanol is very hard to extract from the sulfuric acid/ water solution
• HF/SbF5 is not a reasonable system to convert methane to methanol
• Ionic liquids increase yield and are more water-tolerant
• Realize how this catalyst could be used to further Hydrogen “Car” applications
References
• Cheng, J.; Li, Z.; Haught. M.; Tang. Y. Chem. Commun. 2006, 4617
• Kua, J.; Xu X.; Perenia, R. A.; Goddard, W. A., III. Organometallics 2002, 21, 511.
• Kua, J.; Goddard III, W. J. Am. Chem. Soc. 1999, 121, 10928
• Seidel, S.; Seppelt, K. Inorg. Chem. 2003, 42, 3846
• http://www.fuelcells.org/
• Cool Website Link to See Fuel Cells
• http://www.utcpower.com/fs/com/Videos/UTCPower.wmv