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Andre Chen, Anthony Chiu, Justin Foss, Ryan Ghosh, Joshua Hubbard, Rodrigo Salamanca. Methanol Synthesis Kinetics. Overview. Background Methanol Synthesis Reactions Rate Expression Development Other Kinetic Models Preliminary ASPEN Results. Methanol Background: History. <30 BCE.
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Andre Chen, Anthony Chiu, Justin Foss, Ryan Ghosh, Joshua Hubbard, Rodrigo Salamanca Methanol Synthesis Kinetics
Overview • Background • Methanol Synthesis Reactions • Rate Expression Development • Other Kinetic Models • Preliminary ASPEN Results
Methanol Background: History <30 BCE Ancient Egyptians use pyrolysis of wood to make methanol 1661 Pure methanol produced Cu used as catalyst 1905 BASF (Germany)produces industrial-scale synthetic methanol 1923 2016 85 million metric tonnes produced globally
Methanol Background: Energy Applications Methanol Energy (Mitsubishi Gas Chemical, 2019) Energy resource • Automotive industry: mixed with gasoline for automobile fuel • Heating source • Fuel cells
Methanol Background: Other Applications Methanol Chemicals (Mitsubishi Gas Chemical, 2019) Chemical Industry • Formaldehyde • Acetic Acid • Alkenes (e.g. ethylene) Other Industries • Construction • Electronics
Methanol Background: Market Trends Methanol global growth (ZEEP, 2019) • Asian Growth • US to begin exporting more than importing in 2019 • Impact of weather
Methanol Background: Catalyst Cu/ZnO catalyst (Xu, 2017) Catalyst Type • Cu/ZnO: high selectivity and activity • Al2O3 and/or ZrO2: optional additions • 4-8 year lifetime
Methanol Background: Catalyst Catalyst Mechanism • Initial proposals • Single-site (CO2, H2, & CO compete) • Dual-site (CO2 & CO compete, H2 other side) • Latest proposals • CO2 & CO on different sites • Active site locations still debated
2. Methanol Synthesis: Reactions Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat
Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) 2. Methanol Synthesis: Reactions CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat ‘Only Carbon Monoxide’ Natta, 1955; Bakemeier et al., 1970
Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) 2. Methanol Synthesis: Reactions CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat ‘Only Carbon Dioxide’ Dybkjaer, 1985; Chinchen et al., 1984
Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) 2. Methanol Synthesis: Reactions CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat ‘Both CO and CO2 play a role’ Liu et al. 1985 (Carbon labeling); Denise and Sneeden (Kinetic); Klier et al. (Kinetic)
2. Methanol Synthesis: Reactions Synthesis of Dimethyl Ether (DME) Water-Gas Shift (WGS) Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat CH3OCH3 + H2O (4) 2CH3OH
2. Methanol Synthesis: Reactions Synthesis of Dimethyl Ether (DME) Water-Gas Shift (WGS) Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Major Theme: Inconsistency CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat CH3OCH3 + H2O (4) 2CH3OH
2. Methanol Synthesis: Reactions Water-Gas Shift (WGS) Synthesis of Dimethyl Ether (DME) 48 different kinetic models depending on reaction theory Carbon Dioxide Hydrogenation Major Theme: Inconsistency Carbon Monoxide Hydrogenation CO + 2H2 CH3OH (1) CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat CH3OCH3 + H2O (4) 2CH3OH
3. Rate Expression Development - Graaf Experimental Setup: Spinning basket reactor (Tjabel et al. 1966)
3. Rate Expression Development - Graaf Experimental Setup: Spinning basket reactor (Tjabel et al. 1966) GLC
3. Rate Expression Development - Graaf Experimental Setup: Spinning basket reactor (Tjabel et al. 1966) GLC Water formation (Graaf et al. 1988) Decreasing Pressure
3. Rate Expression Development - Graaf Experimental Setup: Spinning basket reactor (Tjabel et al. 1966) GLC Water formation (Graaf et al. 1988) Decreasing Pressure
3. Rate Expression Development - Graaf Experimental Setup: Spinning basket reactor (Tjabel et al. 1966) GLC Water formation (Graaf et al. 1988) Decreasing Pressure Thermodynamically predicted CO reaction
3. Rate Expression Development - Graaf Experimental Setup: Spinning basket reactor (Tjabel et al. 1966) GLC Water formation (Graaf et al. 1988) Decreasing Pressure Thermodynamically predicted CO reaction Must result from CO2 reaction
Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) 3. Rate Expression Development - Graaf (1) (2) (3) Graaf, G.H., et al.., 1988. Kinetics of low-pressure methanol synthesis. Chemical Engineering Science
3. Rate Expression Development - Graaf Graaf, G.H., et al.., 1988. Kinetics of low-pressure methanol synthesis. Chemical Engineering Science
Reduced form can be inputted to ASPEN 3. Rate Expression Development - Graaf Graaf, G.H., et al.., 1988. Kinetics of low-pressure methanol synthesis. Chemical Engineering Science
4. Other Kinetic Models Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) CO + 2H2 CH3OH (1) 4 Intermediate Steps CO2 + 3H2 CH3OH + H2O (2) (3) CO + H2O CO2 + H2 + Heat
4. Other Kinetic Models Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) CO + 2H2 CH3OH (1) 4 Intermediate Steps CO2 + 3H2 CH3OH + H2O (2) 6 Intermediate Steps (3) CO + H2O CO2 + H2 + Heat
4. Other Kinetic Models Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation Water-Gas Shift (WGS) CO + 2H2 CH3OH (1) 4 Intermediate Steps CO2 + 3H2 CH3OH + H2O (2) 6 Intermediate Steps (3) CO + H2O CO2 + H2 + Heat 2 Intermediate Steps
4. Other Kinetic Models Water-Gas Shift (WGS) Carbon Monoxide Hydrogenation Carbon Dioxide Hydrogenation CO + 2H2 CH3OH (1) 4 Intermediate Steps 4 x 6 x 2 = 48 Different Combinations CO2 + 3H2 CH3OH + H2O (2) 2 Intermediate Steps (3) CO + H2O CO2 + H2 + Heat 6 Intermediate Steps
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Overview of Model Development • Measure CO and CO2 conversion experimentally over a range of conditions • Develop expressions for kinetic parameters • Relate rate expressions to CO and CO2 conversion • Nonlinear regression to obtain kinetic parameters • Test parameters for all 48 kinetic models - identify best performing models
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Experimental Setup Operating Conditions: Catalyst: ??? Reactor system: ??? State variables: ??? Feed: ??? Reactants were input into reactor at variables compositions
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Experimental Setup Operating Conditions: Catalyst: ??? Reactor system: ??? State variables: ??? Feed: ??? Inert gas fed in variable composition with reactants
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Experimental Setup Activity tests were carried out in an isothermal tubular fixed bed reactor (10.2 mm I.D.) with a catalyst weight of 1.0 g. (Cu/ZnO/Al2O3/ZrO2)
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Experimental Setup Reactor temperature and reactant flow rate (in terms of space velocity) were also varied experimentally
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Experimental Setup Operating Conditions: Catalyst: ??? Reactor system: ??? State variables: ??? Feed: ??? Outlet composition was analyzed by gas chromatography
Combinations of varied parameters form 28 experimental conditions for which conversion data was collected
Varied parameters, again, included reactor temperature, space velocity, and feed composition
Averaged error across all 28 conditions contributes to robustness of the developed model to varying conditions
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 Parameter Estimation • Express theoretical CO and CO2 conversion (XCO, calc and XCO2, calc) from rate equations • Use nonlinear regression in MATLAB to get estimated kinetic parameters Kinetic Parameters Objective Function for Nonlinear Regression
4. Lim et al. 2009: Proposed Kinetic Model Based on Influence of CO2 CO Hydrogenation - Step 4 Water-Gas Shift (WGS) - Step 1 CO2 Hydrogenation - Step 2 Choosing Kinetic Model Choosing a kinetic model: • Calculate total average errors • Calculate standard deviation of error • Select kinetic models which give errors/std deviations within threshold values • 17% XCO error • 60% XCO2 error • 10% XCO STD • 30% XCO2 STD
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst PFR 1 Analysis:
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst PFR 1 Analysis: Temperature: 100 - 1000℃
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst PFR 1 Analysis: Temperature: 100 - 1000℃ Pressure: 1 - 101 bar
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst PFR 1 Analysis: Temperature: 100 - 1000℃ Pressure: 1 - 101 bar Max Methanol Flow Rate 303.36 kmol/hr = when T = 300℃; P = 101 bar
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst PFR 2 Analysis: Temperature: 270 - 310℃ Pressure: 80 - 100 bar
5. Preliminary ASPEN Feed: CO = 500 kmol/hr CO2 = 100 kmol/hr H2 = 2000 kmol/hr = 141.37m3 Reactor: Volume = 3000 kg Catalyst PFR 2 Analysis: Temperature: 270 - 310℃ Pressure: 80 - 100 bar Max Methanol Flow Rate 374.26 kmol/hr = when T = 278℃; P = 100 bar
Optimal Operating Temperatures and Pressures 5. Preliminary ASPEN
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