«Von der Fakultät für Mathematik, Informatik und Naturwissenschaften der RheinischWestfälischen Technischen Hochschule Aachen zur Erlangung des ...»
Heterogeneous Catalysis in the different Reactor Types on the
Examples of Ethyl Benzene to Styrene, Methane
Dehydroaromatization and Propylene Carbonate/Methanol
Von der Fakultät für Mathematik, Informatik und Naturwissenschaften der RheinischWestfälischen Technischen Hochschule Aachen zur Erlangung des akademischen
Grades eines Doktors der Ingenieurwissenschaften genehmigte Dissertation
aus Novomoskovsk, Russland
Referent: Universitätsprofessor Dr. rer. nat. W. F. Hölderich Korreferent: Universitätsprofessor Dr.-Ing. M. Modigell Tag der mündlichen Prüfung: 09.07.2009 Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.
This work was carried out at the chair for Technical Chemistry and Heterogeneous Catalysis of RWTH Aachen, Germany, between January 2004 and December 2006.
I would like to acknowledge many people for helping me during my doctoral work.
Especially I wish to thank my advisor, Prof. Dr. Wolfgang Hölderich, for his generous time and commitment. Throughout my doctoral work he encouraged me to develop independent way of thinking and research skills. He continually stimulated my analytical thinking and greatly assisted me with scientific writing.
I thank my second examiner Prof. Dr. Modigell for taking on the task of reviewing this thesis.
I thank my third examiner Prof. Dr. Raabe for a friendly participation on the doctoral examination.
I thank Prof. Dr. Weinhold for taking on the task to be a chairman at the examination.
Also I thank DOW Chemicals, ENI Technology and COST Program of the European Union for the financial support during performing this work.
This dissertation would not have been possible without the technical support of the analytic team. Mrs. E. Biener, Mrs. H. Fickers-Boltz, Mrs. M. Naegler, Mrs. N. Mager, Mr. M.Gilliam and Mr. Vaessen are greatly appreciated for the competent support and nice work atmosphere.
I am extremely grateful for the assistance and advices I received from Dr. John Niederer and Dr. Michael Valkenberg.
I extend many thanks to all my colleagues and friends, who provided very nice and friendly atmosphere and supported me with advices and actions, especially Hans Schuster, Christophe Duquenne, Jose-Maria Menendez-Torre, Sergio Sabater, Rani Jha, Philipp Klement, Stefan Kujath, Adrian Crossman and many other people.
Finally, I would like to thank my family. I am especially grateful to my mother who supported and encouraged me over years. I thank my wife Elena who was constant source of support and enthusiasm.
Of course, despite all the assistance provided by Prof. Dr. Hölderich and others, I alone remain responsible for the content of the following, including any errors or omissions which may unintentionally remain.
To my family
BET – Brunauer, Emmett and Teller, surface area and pore size distribution analysis DMC – Dimethyl Carbonate DMS – Dimethyl Sulfate DPC – Diphenyl Carbonate DSC – Differential Scanning Calorimetry DTG – Differential Thermogravimetry EC – Ethylene Carbonate EG – Ethylene Glycol EO – Ethylene Oxide GC – Gas Chromatography GC-MS – Gas Chromatography with Mass Spectrometry analysis GTL – Gas To Liquids HEMC – HydroxyEthyl Methyl Carbonate HPMC – HydroxyPropyl Methyl Carbonate ICP-AES – Inductively Coupled Plasma Atomic Emission Spectrophotometry MDA – Methane DehydroAromatization MeOH – Methanol MFV – Minimal Fluidization Velocity PC – Propylene Carbonate PG – Propylene Glycol PhOH – Phenol PO – Propylene Oxide TGA – Thermogravimetric Analysis TOS – Time On Stream VHSV – Volume Hourly Space Velocity WHSV – Weight Hourly Space Velocity XRD – X-Ray Diffraction analysis Figures II Figure 1: Secondary building units and their symbols. Number in parenthesis is occurrence frequency. _________________________________________________________________ 7 Figure 2: Pore structure of zeolite Y ____________________________________________ 8 Figure 3: Pore structure of ZSM-5.zeolite: (a) basic unit; (b) linked chains; (c) threedimensional framework; (d) channel system _______________________________________ 9 Figure 4: Zeolite market by different segments – 1999 _____________________________ 10 Figure 5: Reactant selectivity _________________________________________________ 11 Figure 6: Product selectivity __________________________________________________ 11 Figure 7: Restricted transition-state selectivity ___________________________________ 11 Figure 8: Fluidization regimes ________________________________________________ 12 Figure 9: Pressure drop over superficial gas velocity ______________________________ 13 Figure 10: Heat transfer coefficient (bed/wall) over superficial gas velocity at different regimes __________________________________________________________________ 14 Figure 11: Proved natural gas reserves at the end 2005 ____________________________ 21 Figure 12: Distribution of proved natural gas reserves at the end 2005 ________________ 21 Figure 13: Natural gas production by area at the end 2005 _________________________ 22 Figure 14: Natural gas consumption by area at the end 2005 ________________________ 22 Figure 15: Sectoral worldwide natural gas consumption in 1973 and in 2004 ___________ 24 Figure 16: Distribution of a number of published papers to the topic “methane dehydroaromatization” over the years __________________________________________ 26 Figure 17: Riser-reactor set up ________________________________________________ 44 Figure 18: Riser reactor set up picture, shown without isolation and cooling trap ________ 45 Figure 19: Liquid products distribution. 20 mol.% of EB, 600°C. _____________________ 48 Figure 20: Gaseous products distribution. 20 mol.% of EB, 600°C. ___________________ 49 Figure 21: Liquid products distribution. 40 mol.% of EB, 600°C. _____________________ 50 Figure 22: Liquid side products formation at different styrene formation levels, 600°C. ___ 50 Figure 23: Influence of the EB concentration in the feed, 0.68 s GRT and 600°C. ________ 51 Figure 24: Gas products distribution at 600 and 700°C, 0.7 s GRT, only ethane as a feed _ 52 Figure 25: Gaseous product distribution. 20 mol.% of EB, 600°C ____________________ 53 Figure 26: Gas product distribution at 0.7 and 1 s GRT. 700°C, only ethane as a feed ____ 54 Figure 27: Gas products distribution with and without water adding. 1 s GRT, 700°C. ____ 55 Figure 28: Water experiment and blank experiment. 1 s GRT, 700°C. _________________ 56 Figure 30: P&I diagram of the fluidized bed reactor system _________________________ 58 Figure 31: Fluidized bed reactor set up _________________________________________ 59 Figure 32: Aromatic formation rate. 973K, WHSV=2.0 h -1, fixed-bed reactor ___________ 61 Figure 33: Aromatic distribution. 973K, WHSV=2.0 h-1, fixed-bed reactor _____________ 61 Figure 34: Yield of the aromatic in mol.% and its distribution during 16 reaction cycles.
973K, fixed bed reactor ______________________________________________________ 62 Figure 35: X-Ray diffraction of the fresh Mo/HZSM-5 and the spent catalyst after having undergone 16 reaction cycles _________________________________________________ 62 Figure 36: TGA analysis of used catalyst. Mass loss, DSC and DTG, air, 2K/min ________ 64 Figure 37: Methane conversion in fluidized bed reactor. Three reaction cycles are shown.
973K, WHSV=1.44 h-1 _______________________________________________________ 66 Figure 38: Aromatic formation rate in mmol “C”/g*h for fluidized bed reactor. Three reaction cycles are shown. 973K, WHSV=1.44 h-1 _________________________________ 66 Figure 39: Aromatic distribution in mol.% for fluidized bed reactor. First reaction cycle is shown, 973K. ______________________________________________________________ 67 Figure 40: Aromatic distribution in fluidized bed reactor. Third reaction cycle is shown, 973K. ____________________________________________________________________ 67 Figure 41: Particles size distribution of used catalyst after 92 hours under fluidized conditions and fresh catalyst particles. __________________________________________ 70 Figures III Figure 42: Comparison of formation rate of aromatic in fixed and fluidized bed reactors.
700°C (973 K), WHSV=1.4 h-1, VHSV=2000 mlCH4/g Cat*h __________________________ 72 Figure 43: TGA coke analysis after use in fixed and fluidized bed reactors. _____________ 73 Figure 44: Formation rate of aromatic at different WSHV levels, 700°C, VHSV in ml CH4/g cat*h ____________________________________________________________________ 76 Figure 45: Conversion of methane at different WHSV levels, 700°C, VHSV in ml CH4/g cat*h _________________________________________________________________________ 77 Figure 46: Temperatures of two mass loss processes (Peak 1 and Peak 2) and total mass loss in wt.%___________________________________________________________________ 78 Figure 47: H/C molar ratio of the coke after reactions at different WHSV level. _________ 78 Figure 48: Total aromatic yield for the conversion of methane over Mo/HZSM-5 for reaction temperatures of 700°C, 725°C, 800°C and 850°C. ________________________________ 80 Figure 49: Coke total mass loss (secondary axe), peaks mass loss temperatures and H/C ratio of the coke (secondary axe) at different reaction temperatures. _______________________ 80 Figure 50: Total aromatic yield for the conversion of methane over Mo/HZSM-5 for reaction conditions of 3.7g CH4/g Cat*h with varying amounts of carbon dioxide added to the methane feed. Each reaction has been performed with a fresh catalytic bed ___________________ 82 Figure 51: Molar aromatic distribution of benzene for reaction conditions of 3.7 gCH4/g cat*h with varying amounts of carbon dioxide added to the methane feed. Each reaction has been performed with a fresh catalytic bed _______________________________________ 82 Figure 52: Comparison of aromatic formation rate in fluidized and fixed bed reactors, 700°C, 3 mol.% of CO2 in the feed, WHSV=1.4 h-1 ______________________________________ 83 Figure 53: Aromatic distribution during the fluidized bed experiment, 3 mol.% of CO2 ___ 84 Figure 54: Physical mixtures of Mo2C and HZSM-5, Mo/HZSM-5 results are given for comparison. Yields of aromatic in mol.% Conditions: methane WHSV=4.3 h-1, 700°C, aromatic selectivity=100%. __________________________________________________ 85 Figure 55: Flow sheet diagram of fixed bed reactor for propylene carbonate/methanol transesterification __________________________________________________________ 87 Figure 56: Fixed-bed reactor set up ____________________________________________ 87 Figure 57: Overview on MgO-CaO-SrO-BaO activity. PC conversion, selectivity to DMC, DMC yield, PG selectivity and PG yield are shown. _______________________________ 91 Figure 58: CO2-TPD analysis of MgO __________________________________________ 91 Figure 59: CO2-TPD analysis of SrO ___________________________________________ 92 Figure 60: CO2-TPD analysis of BaO __________________________________________ 92 Figure 61: CO2-TPD analysis of CaO __________________________________________ 93 Figure 62: Response surface using quadratic model _______________________________ 95 Figure 63: Response surface using cubic model ___________________________________ 95 Figure 64: GC of the reaction mixture after blank experiment (300°C, 1s reaction time). __ 98 Figure 65: Compounds found in the reaction mixture if HZSM-5 was used as catalyst.