MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY STUDY ON THE SiO2 SUPPORTED IONIC LIQUID PHASE (SILP) CATALYSTS FOR THE HYDROFORMYLATION OF ETHYLENE Speciality: Petrochemistry and catalysis for organic synthesis Code: 62.44.35.01 CHEMISTRY DISSERTATION A thesis submitted to Hanoi University of Science and Technology for the degree of Doctor of Philosophy in Chemistry By Nguyen Thi Ha Hanh SUPERVISORS : Assoc.Prof Dr Vu Dao Thang Assoc.Prof Dr Le Minh Thang INVITED SUPERVISOR: Prof Rasmus Fehrmann HANOI - 2011 ACKNOWLEDGMENTS I would like to thank my supervisors, Assoc Prof Vu Dao Thang, Assoc Prof Le Minh Thang, Prof Rasmus Ferhmann, and Assoc Prof Anders Rissager for their guidance, encouragement, and the academic and financial support in accomplishing this work Many thanks to Dr Olivier Nguyen Van Buu for introducing me to the airsensitive synthetic techniques, the hydroformylation reactor unit I also would like to thank my college - Msc.Truong Duc Duc for all his help in the characterization of catalyst structures presented in this dissertation Very special thanks to my husband Quach and my daughter Minh Khue for their love, support, and encouragement And to my mom, and my dad– thanks for being always there for me I would like to thank to my teachers at Department of Organic and Petrochemical Technology, my colleges at the Laboratory of Petrochemical Refining and Catalysis Materials for their supports, their commendation and their discussions Acknowledgments are also extended to Danida Foundation for funding this research CONTENTS INTRODUCTION CHAPTER 1: LITERATURE REVIEW 1.1 1.1.1 1.1.2 1.1.3 1.1.4 11 14 1.1.6 Hydroformylation of alkenes (Oxo Reaction) The importance of hydroformylation products The role of hydroformylation reaction Catalysts for hydroformylation reaction Recent trends in the heterogeneous hydroformylation reaction Heterogeneous catalysts for vapor phase hydroformylation of alkenes Mechanism of hydroformylation reaction 1.2 SILP catalyst 26 1.2.1 1.2.2 1.2.3 1.3 Composition of SILP catalysts Synthesis of SILP catalysts Catalytic activity of SILP catalysts Aim of thesis 27 33 34 35 1.1.5 17 21 CHAPTER 2: EXPERIMENT 2.1 Catalyst Synthesis 37 2.1.1 Chemicals 37 2.1.2 Synthesis procedures 38 2.2 Catalyst characterization 41 2.2.1 Characterization of surface properties by physical adsorption Infrared (IR) spectroscopy 41 2.2.2 43 2.2.3 Thermal analysis 44 2.2.4 SEM- TEM technichque 45 2.2.5 Nuclear magnetic resonance spectroscopy –NMR 49 2.3 Measurement of density of ionic liquid 50 2.4 Measuarement of catalytic activity 51 2.4.1 Hydroformylation of ethane 50 2.4.2 Hydroformylation of penten 53 2.4.3 Calculation of catalytic activities 54 CHAPTER 3: RESULTS AND DISCUSSION 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 Catalyst characterization The density of ionic liquid NMR spectra of ligand TPPTS-Cs3 TPD NH3 of SiO2 support Thermal analysis of IL, ligand and SILP catalyst Surface area and physical adsorption properties of SILP catalysts 57 57 59 59 60 66 3.1.6 3.1.7 3.1.8 3.2 3.2.1 FTIR characterization SEM observation TEM observation Catalytic activity Catalytic activity of the catalysts using ligand TPPTSCs3 for the hydroformylation of ethylene Influence of ionic liquid loading content on acitivity of SILP Influence of Rhodium content on activity of SILP Influence of ligand/Rh ratios on activity of SILP catalyst Deactivation of catalytic performance 70 75 79 82 83 3.2.1.1 3.2.1.2 3.2.1.3 3.2.1.4 84 87 90 88 2.1.5 3.2.2 3.2.2.1 3.2.2.2 3.2.3 Activation energy Catalytic activity of the catalysts using sulfoxantphos ligand Catalytic activity for the hydroformylation of ethylene Catalytic activity for the hydroformylation of pentene Discussion CONCLUSION References Appendix 93 96 96 103 107 110 111 LIST OF TABLE Table Title Page 1.1 Developments in hydroformylation processes 12 1.2 Classification of immobilised metal complex catalysts 17 1.4 Supported ionic liquid phase hydroformylation in ionic liquids 30 1.5 Supports used for SILP-catalysed hydroformylation of propene 32 2.1 Summary of synthesized catalysts 40 2.2 Retention times of reactants and products in the hydroformylation of ethylene 53 2.3 Retention times of reactants and products in the hydroformylation of pentene 54 3.1 Density of inonic liquid –[BMIM][n- C8H17OSO3],- at different temp 57 3.2 Weight loss due to the decomposition of IL in the samples with different IL loadings, before and after use 65 3.3 Influence of IL loading on the Surface properties of SILPs 66 3.4 Surface properties of SILPs with different ligand and L/Rh ratios 67 3.5 Surface properties of SILP catalysts with different IL loading before and after hydroformyl reaction (used) 68 3.6 Element compositions of different points indicated in figure 3.23 77 LIST OF FIGURES Figure Title Page 1.1 Global consumption of 2–ethylhexanol for various applications (wt %) 1.2 Global consumption of n–butanol and iso–butanol (wt %) 1.3 Worldwide growth in the production of oxo products 1.4 Region wise production statistics for oxo products (2008) 1.5 Statistics of oxo products for Asia region (2003) 1.6 Worldwide oxo product derivatives distribution 10 1.7 Production capacities for oxo products by worldwide known industries 10 1.8 Hydroformylation reaction in biphasic medium 16 1.9 Coordinative anchoring of a metal complex to the support surface 18 1.10 A schlenk line and schlenk tube 33 2.1 The Schlenk system to synthesize catalysts 39 2.2 BET plot 42 2.3 Ways to obtain vibrational spectroscopy: Transmission infrared 44 2.4 A themal Analysis Device 45 2.5 Effects produced by electron bombardment of a material 46 2.6 Transmission electron microscope with all of its components 48 2.7 Spin state of a nulear 49 2.8 A description of the transition energy for a 31P nucleus 49 2.9 Scheme of the reactor set-up 52 2.10 Calibration curve for propanal 56 3.1 Density of inonic liquid [BMIM][n-C8H17OSO3], at different Temperature 58 3.2 Ab Viscosity of [BMIM][n-C8H17OSO3] at different temperature 58 3.3 NMR spectra of synthesized TPPTS-Cs3 ligand 60 3.4 TPD NH3 profiles of uncalcined and calcinated SiO2 61 3.5 TG-DSC profiles of [BMIM][n-C8H17OSO3] (nitrogen atmosphere, heating rate: 5oC/min) 62 3.6 TG-DSC profile of ligand TPPTS-Cs3 (nitrogen atmosphere, heating rate: 5oC/min) 63 3.7 TG-DSC profile of SILP -Cs-L/Rh10-IL10- Rh0.2 (nitrogen atmosphere, heating rate: 5oC/min) 64 3.8 TG-DSC profile of SILP -Cs-L/Rh10-IL50- Rh0.2 (nitrogen atmosphere, heating rate: 5oC/min) 64 3.9 TG-DSC profile of SILP -Cs-L/Rh10-IL30- Rh0.2 (nitrogen atmosphere, heating rate: 5oC/min) 64 3.10 TG-DSC profile of SILP -SX-L/Rh10-IL10- Rh0.2 (nitrogen atmosphere, heating rate: 5oC/min) 64 3.11 BJH desorption profiles of samples with different IL loading content before (a) and after the reaction (used) (b) 69 3.12 FT-IR spectrum of SiO2, TPPTS-Cs3 ligand, IL and SILP-Cs-L/Rh10IL10-Rh0.2 70 3.13 FT-IR spectra of SILP catalyst using TPPTS ligand with different IL 71 loading contents 3.14 FT-IR spectra of SILP catalyst using TPPTS ligand with different L/Rh ratios 72 3.15 FT-IR spectra of SILP catalyst using TPPTS ligand with different Rh loading contents 72 3.16 FT-IR spectra of SILP catalysts with different IL loading before and afer exposed to high temperatures of the reactions 73 3.17 FT-IR spectra of SILP catalysts with different Rh loading before and afer exposed to high temperatures of the reactions 74 3.18 SEM images of SiO2 support 75 3.19 SEM images SILP-Cs-L/Rh10-IL5-Rh0.2 75 3.20 SEM images SILP-Cs-L/Rh10-IL10-Rh0.2 75 3.21 SEM images SILP-Cs-L/Rh10-IL20-Rh0.2 76 3.22 SEM images SILP-Cs-L/Rh10-IL50-Rh0.2 76 3.23 Positions for EDX measurement and EDX spectra of SILP-CsL/Rh10-IL10-Rh0.2 catalyst: 77 a) position for EDX measurement, b) EDX spectrum at S1, c) EDX spectrum at S2, d) EDX spectrum at S3 3.24 SEM images of SILP-Cs-L/Rh10-IL5-Rh0.2 before and afer exposed to high temperatures of the reactions 78 3.25 SEM images of SILP-Cs-L/Rh10-IL10-Rh0.2 before and afer exposed to high temperatures of the reactions 79 3.26 SEM images of SILP-Cs-L/Rh10-IL50-Rh0.2 before and afer exposed to high temperatures of the reactions 79 3.27 TEM images of SiO2 support 80 3.28 TEM images of SILP-Cs-L/Rh10-IL5-Rh0.2 before and afer exposed to high temperatures of the reactions 80 3.29 TEM images of SILP-Cs-L/Rh10-IL10-Rh0.2 before and afer exposed to high temperatures of the reactions 81 3.30 TEM images of SILP-Cs-L/Rh10-IL10-Rh0.2 before and afer exposed to high temperatures of the reactions 81 3.31 TEM images of SILP catalysts with different Rh loading 82 3.32 Catalytic activity of SILP catalysts with different IL loading 85 3.33 Influence of IL loading contents on the maximum temperature which the catalysts still work stably 85 3.34 Influence of IL loading content on the catalytic activity of SILP catalysts 86 3.35 Influence of Rh content on the activity of SILP catalysts 87 3.36 Influence of ligand/Rh ratios on the catalytic activity of SILP catalysts 88 3.37 Influence of ligand/Rh ratios on the maximum temperature which the catalysts still work stably 89 3.38 TOF at 90oC (except for the sample with 50%IL, which TOF is at 80oC since the catalyst start to loose activity from 90oC already) of the catalysts with different IL loading contents before and after the exposition to high temperatures 90 3.39 TOF at 90oC of the catalysts with different Rh loading contents before and after the exposition to high temperatures 91 Appendix 26: Surface area and pore size distribution of used SILP –Cs – L/Rh10 –IL20-Rh0.2 25 Appendix 27: Surface area and pore size distribution of used SILP –Cs – L/Rh10 –IL30-Rh0.2 26 Appendix 28: Surface area and pore size distribution of used SILP –Cs – L/Rh10 –IL50-Rh0.2 27 Appendix 29: GC spectrum of Ethylene (in raw material gas, in stabilization stage) before running hydroformylation reaction Software Version Operator Sample Number AutoSamler Instrument Name Instrument Serial# Delay time Sampling Rate Sample Volume Sample Amount Data acquisition Time 6.3.1.0504 Ar 009 NONE Autosystem XL 610N6050802 0.00 1.5625pts/s 1.00000ml 1.00000 16/5/2008 9:10:16 Date Sample Study Rack/Vial Channel A/D mV Range End time 16/5/2008 9:26:21 C2 C2 hyd 0/0 A 1000 Area Reject Dilution Factor Cycle 0.000000 1.00 Raw Data File: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\Stabiliztion- C2 Hyd study\ar_1652008_A_009.raw Inst Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15 from C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_1652008_A_009.raw Proc Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Calib Method:C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Report Format File: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15.rpt Sequence File: C:\Documents and Settings\ar\Dokumenter\GC data\sequences\C2 Hydroformylation s.seq DEFAULT REPORT Peak Time [min] 2.59 Area Height [µV.s] [µV] Area [%] Norm.Area [%] 602928 32862.03 100.00 100.00 602928 32862.03 100.00 100.00 BL Area/Height [s] BB Chromatogram Sample Name: Sample #009 Page of 18.3473 File name: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\Stailization-C2 Hyd study\ar_1652008_A_009.raw Date: 16/5/2008 Method: auto 70 keep 2min 190 15mins.15 Auto Time of injection: 16/5/2008 9:10:21 Start time: 2.55 End Time: 14.59min Low Point: 4.83mV High Point: 125.13mV Appendix 30: GC spectrum of Propanal standard Software Version Operator Sample Number AutoSamler Instrument Name Instrument Serial# Delay time Sampling Rate Sample Volume Sample Amount Data acquisition Time 6.3.1.0504 Ar 009 NONE Autosystem XL 610N6050802 0.00 1.5625pts/s 1.00000ml 1.00000 20/5/2008 9:50:16 Date Sample Study Rack/Vial Channel A/D mV Range End time 20/5/2008 9:56:51 C2 C2 hyd 0/0 A 1000 Area Reject Dilution Factor Cycle 0.000000 1.00 Raw Data File: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\Standard aldehyde C2 Hyd study\ar_2052008_A_009.raw Inst Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\Injection 70 keep 2min 190 15mins.15 from C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_2052008_A_009.raw Proc Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\Injection 70 keep 2min 190 15mins.15mth from Calib Method:C:\Documents and Settings\ar\Dokumenter\GC data\methods\Injection 70 keep 2min 190 15mins.15mth from Report Format File: C:\Documents and Settings\ar\Dokumenter\GC data\methods\Injection 70 keep 2min 190 15mins.15.rpt Sequence File: C:\Documents and Settings\ar\Dokumenter\GC data\sequences\Propanal standard for Hydroformylation s.seq DEFAULT REPORT Peak Time [min] 7.75 Area Height Area [%] Norm.Area [%] [µV.s] [µV] 89313.31 8937.59 100.00 100.00 89313.31 8937.59 100.00 100.00 BL Area/Height [s] BB 9.9930 Chromatogram Sample Name: Sample #019 Page of File name: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\ Standard aldehyde C2 Hyd study\ar_2052008_A_009.raw Date: 20/5/2008 Method: Injection 70 keep 2min 190 15mins.15 Auto Time of injection: 20/5/2008 9:56:51 Start time: 7.77 End Time: 7.79min Low Point: 4.83mV High Point: 85.13mV Appendix 31: GC spectrum with SILP-SX-L/Rh-IL10-Rh0.2 in the hydroformylation of ethylene at 70OC, total pressure: 10bars, H2:CO =1:1 (molar ratio) Gas flow rate: 10ml/min, the amount of catalyst is 0.2g Ethylene partial pressure was bar Software Version Operator Sample Number AutoSamler Instrument Name Instrument Serial# Delay time Sampling Rate Sample Volume Sample Amount Data acquisition Time 6.3.1.0504 Ar 009 NONE Autosystem XL 610N6050802 0.00 1.5625pts/s 1.00000ml 1.00000 6/6/2008 9:10:16 Date Sample Study Rack/Vial Channel A/D mV Range End time 6/6/2008 9:26:21 C2 C2 hyd 0/0 A 1000 Area Reject Dilution Factor Cycle 0.000000 1.00 Raw Data File: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_662008_A_009.raw Inst Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15 from C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_1672008_A_009.raw Proc Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Calib Method:C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Report Format File: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15.rpt Sequence File: C:\Documents and Settings\ar\Dokumenter\GC data\sequences\C2 Hydroformylation s.seq DEFAULT REPORT Peak Time [min] Area Height [µV.s] [µV] Area [%] Norm.Area [%] BL Area/Height [s] 2.59 830628 32862.03 97.72 97.72 BB 25.2763 2.88 594.99 297.57 0.70 0.70 BB 1.995 7.75 18833.31 2690.59 2.22 2.22 BB 6.99997 850056.30 35850.16 100.00 100.00 Chromatogram Sample Name: Sample #099 Page of File name: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_662008_A_009.raw Date: 6/6/2010 Method: auto 70 keep 2min 190 15mins.15 Auto Time of injection: 6/6/2008 9:26:21 Start time: 2.55 End Time: 14.59min Low Point: 4.83mV High Point: 5.13mV Appendix 32: GC spectrum with SILP-SX-L/Rh-IL10-Rh0.2 in the hydroformylation of ethylene at 80OC, total pressure: 10bars, H2:CO =1:1 (molar ratio) Gas flow rate: 10ml/min, the amount of catalyst is 0.2g Ethylene partial pressure was bar Software Version Operator Sample Number AutoSamler Instrument Name Instrument Serial# Delay time Sampling Rate Sample Volume Sample Amount Data acquisition Time 6.3.1.0504 Ar 009 NONE Autosystem XL 610N6050802 0.00 1.5625pts/s 1.00000ml 1.00000 7/6/2008 9:10:16 Date Sample Study Rack/Vial Channel A/D mV Range End time 7/6/2008 9:26:21 C2 C2 hyd 0/0 A 1000 Area Reject Dilution Factor Cycle 0.000000 1.00 Raw Data File: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_762008_A_009.raw Inst Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15 from C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_672008_A_009.raw Proc Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Calib Method:C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Report Format File: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15.rpt Sequence File: C:\Documents and Settings\ar\Dokumenter\GC data\sequences\C2 Hydroformylation s.seq DEFAULT REPORT Peak Time [min] Area Height [µV.s] [µV] Area [%] Norm.Area [%] BL Area/Height [s] 2.59 102928 32762.03 59.55 59.55 BB 3.1416 2.88 4594.99 2192.57 2.65 2.65 BB 2.0957 7.75 65313.31 8997.59 37.80 37.80 BB 7.2589 177319.17 43932.32 100.00 100.00 Chromatogram Sample Name: Method: auto 70 keep 2min 190 15mins.15 Auto Start time: 2.55 End Time: 14.59min Sample #109 Page of Time of injection: 7/6/2008 9:26:21 Low Point: 4.83mV High Point: 5.13mV File name: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_762008_A_009.raw Date: 7/6/2008 Appendix 33: GC spectrum with SILP-SX-L/Rh-IL10-Rh0.2 in the hydroformylation of ethylene at 100OC, total pressure: 10bars, H2:CO =1:1 (molar ratio) Gas flow rate: 10ml/min, the amount of catalyst is 0.2g Ethylene partial pressure was bar Software Version Operator Sample Number AutoSamler Instrument Name Instrument Serial# Delay time Sampling Rate Sample Volume Sample Amount Data acquisition Time 6.3.1.0504 Ar 009 NONE Autosystem XL 610N6050802 0.00 1.5625pts/s 1.00000ml 1.00000 6/7/2008 9:10:16 Date Sample Study Rack/Vial Channel A/D mV Range End time 6/7/2008 9:26:21 C2 C2 hyd 0/0 A 1000 Area Reject Dilution Factor Cycle 0.000000 1.00 Raw Data File: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_672008_A_009.raw Inst Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15 from C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_672008_A_009.raw Proc Method: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Calib Method:C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15mth from Report Format File: C:\Documents and Settings\ar\Dokumenter\GC data\methods\auto 70 keep 2min 190 15mins.15.rpt Sequence File: C:\Documents and Settings\ar\Dokumenter\GC data\sequences\C2 Hydroformylation s.seq DEFAULT REPORT Peak Time [min] Area Height [µV.s] [µV] Area [%] Norm.Area [%] BL Area/Height [s] 2.59 102928 32862.03 56.18 56.18 BB 3.1321 2.88 4594.99 2102.57 2.50 2.50 BB 2.1854 7.75 69313.31 8937.59 37.83 37.83 BB 7.7553 11.61 68.36 35.11 0.03 0.03 MM 4.5241 14.59 6314.51 65.02 0.34 0.34 MM 97.1164 183219.17 43982.32 100.00 100.00 Chromatogram Sample Name: Sample #057 Page of File name: C:\Documents and Settings\ar\Skrivebord\GC data\hanh\SILP C2 Hyd study\ar_672008_A_009.raw Date: 6/7/2008 Method: auto 70 keep 2min 190 15mins.15 Auto Time of injection: 6/7/2008 9:26:21 Start time: 2.55 End Time: 14.59min Low Point: 4.83mV High Point: 5.13mV Appendix 34: GC –MS spectrum the sample collected by vacumming (heavy byproduct) with SILP –SX –L/Rh10 –IL10-Rh0.2 in the hydroformylation of ethylene at 80OC, total pressure: 10 bar, H2:CO = 1:1(molar ratio), Gas flow rate: 10ml/min, the amount of catalyst is 0.2g Ethylene partial pressure was bar Name: Pentanal, 3-hydroxy-2-methyl-
F ormula: C6H12O2
 MW: 116 CAS #: 615 30-5 NIST#: 151156 ID#: 23098 DB: mainlib Other DBs: HODOC, NIH 
C ontributor: Chemical Concepts
 10 58 999 | 29 754 | 41 736 | 27 629 | 31 597 | 59 544 | 57 474 | 28 415 | 39 267 | 55 251 | Synonyms: 1.3-Hydroxy-2-methylpentanal # ... 1.1.6 Hydroformylation of alkenes (Oxo Reaction) The importance of hydroformylation products The role of hydroformylation reaction Catalysts for hydroformylation reaction Recent trends in the heterogeneous... knowledge in the field of hydroformylation of alkenes in liquid phase and especially in the gas phase condition 1.1 Hydroformylation of alkenes (Oxo Reaction) Hydroformylation is one of the oldest... development for the hydroformylation reaction 13 1.2 Hydroformylation of ethylene and propylene 22 1.3: Dissociative mechanism for hydroformylation cycle 22 1.4 Associative mechanism for hydroformylation