Vanadium-Phosphorous-Oxygen Industrial Catalysts for C4 Hydrocarbon Selective Oxidation to Maleic Anhydride Robert Wayne Wenig Iowa State University
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1986 Vanadium-phosphorous-oxygen industrial catalysts for C4 hydrocarbon selective oxidation to maleic anhydride Robert Wayne Wenig Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Chemical Engineering Commons Recommended Citation Wenig, Robert Wayne, "Vanadium-phosphorous-oxygen industrial catalysts for C4 hydrocarbon selective oxidation to maleic anhydride " (1986). Retrospective Theses and Dissertations. 8321. https://lib.dr.iastate.edu/rtd/8321 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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For the Na]or Department Signature was redacted for privacy. For tlfie (^djftate College Iowa State University Ames, Iowa 1986 ii TABLE OF CONTENTS Page GENERAL INTRODUCTION 1 Selective Oxidation Processes 1 Catalysts for Maleic Anhydride Synthesis 1 Reaction Pathways 6 Peroxide Mechanisms 7 Redox Mechanism 9 Research Objectives 10 Explanation of Dissertation Format 10 SECTION I. V-P-0 INDUSTRIAL CATALYSTS FOR n-BUTANE OXIDATION: CHARACTERIZATION AND KINETIC MEASUREMENTS 11 ABSTRACT 12 INTRODUCTION 13 EXPERIMENTAL METHODS 14 Catalyst Preparation 14 Characterization Techniques 14 Surface area measurements 14 X-ray diffraction 15 Fourier transform infrared spectroscopy 15 Laser Raman spectroscopy 15 Scanning electron microscopy 15 X-ray photoelectron spectroscopy 16 Catalyst Activity Measurements 16 EXPERIMENTAL RESULTS 18 Characterization of Precipitated Catalysts 18 Surface area measurements 18 X-ray diffraction 18 Laser Raman spectroscopy 21 iii Infrared spectroscopy 23 Scanning electron microscopy 26 X-ray photoelectron spectroscopy 27 Kinetic Measurements for n-Butane Oxidation 27 Conversion and selectivity of V-P-0 catalysts 27 Product yields 42 Specific rates of oxidation 44 Characterization of Used Catalysts 44 X-ray diffraction 44 Laser Raman spectroscopy 49 Infrared spectroscopy 51 Scanning electron microscopy 51 X-ray photoelectron spectroscopy 55 DISCUSSION OF RESULTS 57 CONCLUSIONS 59 REFERENCES 60 SECTION II. MALEIC ANHYDRIDE CONVERSION BY V-P-0 CATALYSTS 62 ABSTRACT 63 INTRODUCTION 64 EXPERIMENTAL PROCEDURE 66 Catalyst Preparation 66 Maleic Anhydride Conversion Measurements 66 EXPERDÎENTAL RESULTS 71 Effect of Temperature 71 Effect of Catalyst Phosphorus Loading 71 DICUSSION OF RESULTS 74 Conversion of Maleic Anhydride to Maleic Acid 74 CONCLUSIONS 77 iv ACKNOWLEDGEMENT 78 REFERENCES 79 SECTION III. IN SITU FTIR STUDY OF n-BUTANE SELECTIVE OXIDATION TO MALEIC ANHYDRIDE ON V-P-0 CATALYSTS 80 ABSTRACT 81 INTRODUCTION 82 EXPERIMENTAL PROCEDURE 85 Catalyst Preparation 85 Catalyst Characterization and Activity Measurements 85 In Situ FTIR Cell and Gas Delivery System 87 Fourier Transform Infrared Spectrometer 87 Catalyst Preparation for ^ Situ Spectroscopic Studies 89 RESULTS 90 Catalyst with P/V = 0.9 91 Catalyst with P/V = 1.0 95 Catalyst with P/V = 1.1 99 DISCUSSION 103 CONCLUSIONS 112 ACKNOWLEDGEMENT 113 REFERENCES 114 SECTION IV. IN SITU FTIR SPECTROSCOPY OF 1-BUTENE AND 1,3-BUTADIENE SELECTIVE OXIDATION TO MALEIC ANHYDRIDE ON V-P-0 CATALYSTS 117 ABSTRACT 118 INTRODUCTION 119 V EXPERIMENTAL PROCEDURE 121 Catalyst Synthesis and Characterization 121 Kinetic Measurements 121 Catalyst Wafer Preparation 121 In Situ FTIR Cell and Gas Delivery System 122 Fourier Transform Infrared Spectrometer 122 RESULTS 123 1-Butene Studies 123 Catalysts with P/V = 0.9 123 Catalysts with P/V =1.0 126 Catalysts with P/V = 1.1 128 1,3-Butadiene Studies 130 Catalysts with P/V =0.9 130 Catalysts with P/V = 1.0 132 Catalysts with P/V = 1.1 132 DISCUSSION 136 CONCLUSIONS 145 ACKNOWLEDGEMENT 146 REFERENCES 147 SECTION V. IN SITU FTIR STUDY OF CROTYL ALCOHOL, MALEIC ACID, CROTONIC ACID, AND MAL.EIC ANHYDRIDE OXIDATION ON A V-P-O INDUSTRIAL CATALYST 149 ABSTRACT 150 INTRODUCTION 151 EXPERIMENTAL PROCEDURE 153 Characterization and Kinetic Measurements 153 In Situ FTIR Cell 153 Vapor Delivery System 153 vi Vacuum System 154 Fourier Transform Infrared Spectrometer 154 RESULTS 155 Crotyl Alcohol 155 Maleic Acid 158 Crotonic Acid 161 Maleic Anhydride 162 DISCUSSION 166 Crotyl Alcohol 166 Maleic Acid 168 Crotonic Acid 168 Maleic Anhydride 171 CONCLUSIONS 172 ACKNOWLEDGEMENT 173 REFERENCES 174 SECTION VI. V-P-0 INDUSTRIAL CATALYSTS FOR C, HYDROCARBON 4 OXIDATION; REACTION MECHANISM 176 ABSTRACT 177 INTRODUCTION 178 DISCUSSION OF RESULTS 182 Maleic Anhydride Oxidation 182 Maleic Acid Oxidation 183 1,3-Butadiene Oxi.dation 184 1-Butene Oxidation 187 n-Butane Oxidation 190 2-Buten-l-ol and 2-Butenoic Acid Oxidation 193 vii CONCLUSIONS 197 ACKNOWLEDGEMENT 198 REFERENCES 199 SUMMARY AND RECOMMENDATIONS 201 Summary 201 Recommendations 202 ADDITIONAL LITERATURE CITED 204 ACKNOWLEDGEMENTS 206 APPENDIX 207 Gas Chromatograph Analytical System 207 1 GENERAL INTRODUCTION Selective Oxidation Processes Selective oxidation reactions with transition metal oxide catalysts have found commercial application for the conversion of hydrocarbons into chemical intermediates. The partial oxidation of napththalene to phthalic anhydride and benzene to maleic anhydride by supported V^O^ catalysts are examples of selective oxidation processes. A current application of hydrocarbon selective oxidation involves the partial oxida tion of hydrocarbons to maleic anhydride by vanadium-phosphorus mixed oxide catalysts. A survey of industrial selective oxidation reactions is presented in Table 1 (1). Selective oxidation catalysts provide a controlled donation of oxygen to the hydrocarbon molecule in order to restrict the formation of complete oxidation products. Active centers are provided by the metal oxide catalysts to assist in the transformation of the reactant into reaction intermediates and oxidation products. The nature of this interaction and the reaction mechanism for commercial selective oxidation reactions are poorly understood. Catalysts for Maleic Anhydride Synthesis Maleic anhydride is an important intermediate in the formation of unsaturated polyester resins and specialty chemicals (2). Worldwide capacity for maleic anhydride production now exceeds 700,000 tonnes per year (3). An important recent advance in this process is the development of vanadium-phosphorus-oxygen (V-P-O) catalysts which are capable of selectively oxidizing n-butane and 1-butene to maleic anhydride. The Table 1. Industrial selective oxidation processes Reaction Catalyst Reactor 00 4... ocl + 2C0 + 2HgO Supported Fluldized bed e 0 O +2CO2 + 2H2O Supported VgO^ + MoO^ Fluldized bed c = 0 Promoted V-P-0 HgC=CHCH2CH^ + 3 °2 " („/ + 3HgO Fixed bed 0 CssO CH^CHgCHgCH^ + Y Og (f \) + AH^O Promoted V-P-0 Fixed bed CH^OH + 2 °2 HCHO + H^O Fe(MoO^)^ + MoO^ Fixed bed 0 1 / \ HGC=CH + 2 ^2'^ H C-CH Supported Ag Fixed bed HgC=CHCHg + 2 ^2 ^ H2C=CHC0gH Mixed molybdates Fixed bed 3 hydrocarbon based oxidation processes are favored by higher theoretical yields and lower feedstock costs than is possible with the earlier benzene based oxidation processes (2). Industrial V-P-0 catalysts often contain Zn, Ti, Co, or Mo promoters and are reported to give high conversions of n-butane and high selectlvitles for malelc anhydride (3, 4). A survey of patented catalysts for the selective oxidation of n-butane to malelc anhydride is presented in Table 2 (3). Typically