METHANOL SYNTHESIS ON COPPER-BASED CATALYSTS   M.V. Bukhtiyarova MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION

Introduction Methanol production is a large industrial process. Methanol is produced using synthesis gas at 250°C and 50 – 100 bars CO + 2H2 = CH3OH Catalyst: Cu/ZnO/Al2O3 High emission of CO2 resulted in studying methanol synthesis through CO2 hydrogenation. Methanol can be viewed as a way of hydrogen storage MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION

Methanol synthesis CO2 + 3H2 CH3OH +H2O Methanol synthesis setup Gas mixture: H2:CO2 = 3:1 Pressure: 30 and 50 bars Temperature: 190, 210, 230, 250 and 260°C GHSV: 4800 and 7200 h-1 MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Süd-Chemie catalyst : Cu/ZnO/Al2O3 (old generation)

Sample obtained at 250°C, 30 bar, 7200 h-1 Gas chromatography of liquid sample Sample obtained at 250°C, 30 bar, 7200 h-1 Samples are dissolved in acetone to have reproducible results Reference methylformate solution contains 5% of methanol 1 2 1 2 3 air Reference methylformate acetone Sample MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION No. Ret.Time Peak Name Rel.Area min % 1 1.69 Methyl formate 0.014 2 2.02 n.a. 0.015 3 2.98 Methanol 99.970 No. Ret.Time Peak Name Rel.Area min % 1 2.50 Methanol 48.277 2 3.31 Wasser 51.723 Traces of methylformate are observed during methanol synthesis

Increasing temperature promotes water-gas shift reaction Methanol synthesis MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Methanol synthesis: Reverse water gas shift: CO2 + 3H2 CH3OH +H2O CO2 + H2 CO +H2O H = – 49.7 kJ/mol H = 41.2 kJ/mol Ratio of CH3OH/H2O (ml/ml) = 2.24 Increasing temperature promotes water-gas shift reaction

Methanol synthesis Dependence on pressure MS: RWGS: MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION MS: CO2 + 3H2 CH3OH +H2O RWGS: CO2 + H2 CO +H2O According to Chatelier’s principle increase of pressure results in higher methanol formation

Volume of formed methanol and water depends on reaction conditions Methanol synthesis Dependence on space velocity MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Volume of formed methanol and water depends on reaction conditions

Methanol synthesis Dependence on space velocity at high pressure MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Volume of methanol and water does not practically change at temperature higher than 250°C

CO2 conversion Dependence on pressure Dependence on space velocity GHSV = 4800 h-1 Dependence on space velocity p = 30 bar MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Conversion of CO2 increase with temperature and decrease with space velocity

Methanol selectivity Dependence on space velocity p = 30 bar Dependence on pressure GHSV = 4800 h-1 MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION At high pressure selectivity practically does not change with temperature

Methanol yield Dependence on space velocity p = 30 bar Dependence on pressure GHSV = 4800 h-1 MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Methanol yield increases with temperature, pressure and decreases with space velocity

Activation energy Comparison with literature data MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Obtained activation energy is in the agreement with activation energy presented in literature

Methanol synthesis Conditions for stability test: H2:CO2 = 3:1; 30 bar, 230°C; 4800 h-1 MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION Productivity of methanol decreases during first 100 after that the catalyst works stable for another 300 hours

Methanol synthesis Methanol synthesis: CO2 + 3H2 CH3OH +H2O Gas mixture: H2:CO2 = 3:1 Pressure: 30 bar Temperature: 190, 210, 230, 250 and 260°C GHSV: 4800 h-1 Clariant (Süd-Chemie) catalysts MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION The “old generation” catalyst works better for CO2 hydrogenation at low pressure

Conclusions Methanol yield depends on reaction conditions: high pressure results in formation of higher amount of methanol Practically pure methanol with trace amount of methylformate is produced Clariant (Süd-Chemie) catalyst for methanol synthesis is stable during long-term experiment for 400 hours Clariant (Süd-Chemie) catalyst of old generation is more suitable for production methanol by CO2 hydrogenation MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION

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Methanol yield MAX-PLANCK-INSTITUT FÜR CHEMISCHE ENERGIE KONVERSION

Gas chromatography of liquid samples Instrument Agilent 6890 Detektor TCD 250°C Column: Stabilwax 30 m S-1 Injector 250°C Programm TCD 60 Tem.Programm 80°C Method Wasser Gas He 0,93 bar 1 ml Report Rep Wasser Split 1:20 Injection Volume 0.5 µl Instrument 6890 Detektor FID 300°C Column: Stabilwax 30m S-69 Injector 240°C Programm Stabilwax Tem.Programm: 50°C Method Pyrrol Gas: H2 0,86 bar 2,3 ml Report Rep normal Split 1:20 Injection Volume: 0.5 µl The measurement using FID was done for determination organic impurities in methanol. FID does not detect water