Vapor Phase Oxidation of Chloropropenes Over Heterogeneous Catalyst Systems
Total Page：16
File Type：pdf, Size：1020Kb
University of Central Florida STARS Retrospective Theses and Dissertations 1976 Vapor Phase Oxidation of Chloropropenes Over Heterogeneous Catalyst Systems Tim Ellis Owen University of Central Florida Part of the Chemistry Commons Find similar works at: https://stars.library.ucf.edu/rtd University of Central Florida Libraries http://library.ucf.edu This Masters Thesis (Open Access) is brought to you for free and open access by STARS. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of STARS. For more information, please contact [email protected]. STARS Citation Owen, Tim Ellis, "Vapor Phase Oxidation of Chloropropenes Over Heterogeneous Catalyst Systems" (1976). Retrospective Theses and Dissertations. 246. https://stars.library.ucf.edu/rtd/246 • VAPOR PHASE OXIDATION OF CHLOROPROPENES OVER HETEROGENEOUS CATALYST SYSTEMS BY TIM ELLIS OWEN B. S ., Northern Kentucky University, 1975 A RESEARCH REPORT Submitted to the Faculty of Florida Technological University in partial fulfillment of the requirements for the degree of Master of Science in Industrial Chemistry in The Department of Chemistry Orlando, Florida November, 1976 • VAPOR PHASE OXIDATION OF CHLOROPROPENES OVER HETEROGENEOUS CATALYST SYSTEMS by Tim E. Owen Abstract Propylene Dichloride (PDC) is a byproduct of several Dow processes. The thermal cracking of PDC produces l - ci~ chloropropene , I - trans-chloropropene, 2- chloropropene , and allyl chloride . By oxidizing the l - and 2-chloropropenes to 3- and 2- chloroacrylic acids , respectively, a potentially valuable product could be made . The chloropropenes, air , and steam were passed over various heterogeneous oxidation catalyst systems to attempt this oxidation . Contact time was varied between 0 . 0951 to 0 . 915 sec. Temperature was varied between 275"C to .25"C . The air content of the feed was varied between .1 to 75% . The chloropropene content of the feed was varied between 2 . 9% to 5 . 0% . The following supported catalysts were tested Co/Mo (3/7)- alumina pellets , CoMoO. - alumina granules , CoMo0 4- silica gel , AcNbMo- alumina pellets , two bed catalyst MoFeTeRe- MoVGeMo - silica gel , CoMoTe - silica gel, and CoMoBi -alumina pellets . No chloroacroleins , or chloroacrylic acids were detected in the reaction products . In general, no CO and from 5- 15% CO 2 was obtained in the reaction products with the alumina and sil ica support materials. Oxidation .over the metal catalysmproduced 0- 10% CO and 5- 40% CO . Severe carbon 2 ization of the supports with and without the metal catalysts was obser ved at the reaction conditions described above. Chloropropenes were found to be unstable, decomposing to car bon at 300°C in an empty reactor at a contact time greater than 0 . 1 sec . Chloroacrylic acids at a 0.1 sec contact time were tested in the reactor over alumina and silica support materials at 200°C and above, and found to be unstable with regard to decomposition to coke . It was concl uded that the vapor phase oxidation of chloropropenes over heterogeneous catalysts to chloroacrylic acids is not feasible because of their decomposition to car bon at the prevailing r eaction conditions . 11i •• ACKNOWLEDGMENTS The author would like to thank Dr. Chris Clausen for his guidance and patience in directing this research; and to his family for spending the summer at Baton Rouge, Louisiana, while this work was under way . The author would also like to thank Dow Chemical USA for supporting this project financially. Without the help of Dr. Graeme Baker in obtaining financial support at Florida Technolog ical University the author could not have completed the coursework for this degree . Dr. Steve Knudson's help in scheduling the teaching assistantships around the course work and research was greatly appreciated. The author would also like to thank his committee members for reviewing this project . Finally a special thank you to my family for moral support 11hile studying for this degree. iv • TABLE OF CONTENTS ABSTRACT • • • • .ii ACKNOWLEDGEMENTS iii LIST OF TABLES . .vi LIST OF ILLUSTRATIONS. viii CHAPTER I INTRODUCTION . 1 Separation of Chloropropenes . .. 2 Chloropropene Oxidation Process and Product Value 4 Separation of Oxidation Products . 5 Summary of Problem .. ... .. 7 II THEORETICAL ASPECTS OF THE CHLOROPROPENE OXIDATION PROCESS. .. 8 III REACTOR DESIGN AND OPERATION 11 Reactor Equipment and Design 11 Reactor Operation . 13 IV ANALYTICAL METHODS AND THERMAL ANALYSIS OF ACIDS 14 Gas Chromatography Methods . 14 Results of Thermal Analysis of the Chloroacrylic Acids . ..... 16 V CATALYST PREPARATION AND DESIGN .. 18 Review of Heterogeneous Catalysts in General 18 Heterogeneous Catalysts Chosen From the Literature . 18 Incipient Wetness Method . 22 Preparation of CoMo Catalysts . 23 Preparation of AsNbMo Catalyst . 24 Preparation of Two Bed Catalyst. 25 Preparation of CoMoTe Catalyst 26 Preparation of CoMoBi catalyst 26 Summary of Catalysts Prepared. 27 v CHAPTER VI RESULTS AND DISCUSSION . 28 Catalyst Carbonization . 28 Thermal Stabili ty of the Chloroacrylic Acids at Run Conditions . 28 Catalyst Test Method . 31 Effects of Catalyst Supports on Chloropropene . 33 Effect of Catalysts on Chloropropene Oxidation 38 VII CONCLUSIONS . 46 APPENDIX A 47 APPENDIX B 58 FOOTNOTES . 60 BIBLIOGRAPHY 62 v i • LIST OF TABLES Table Page 1 Pyrolysis Products of 1 , 2- Dichloropropene (500°C) . 2 2 Solubilities of Light Boiling Chloropropenes 3 3 Melting Points of the Chloropropenes . · . 3 4 Properties of Compounds in Chloropropene Oxidation Stream . .. 6 5 Acrylic Acid Catalysts Selected From the Li terature. .... .. .. .. · . 19 6 Cl assi fication of Acrylic Acid Catal yst Systems. 22 7 Catalysts Prepared for This Study . • 27 8 Catalyst Carbonization Test Data . • • • 29 9 Per Cent Chlor oacrylic Acids Sur viving Reaction Conditions . .. ... 30 10 Per Cent 2- Chloroacrylic Acid Surviving at 200°C and 250°C . ... • 31 11 Catalyst Test Run Sequence • 32 12 Catalyst Support Test Run Data • • 34 13 Catalyst Test Run Data . • • 39 14 Initial and Final Concentrations of Components in the Ch l oropropene Oxidati on . 49 15 ~G Calculation for Chloropropene (298°K) . 51 16 ~G Cal culation for Chloroacroleins (298°K) 52 17 ~G Calculation for Chloroacrylic Acids (298°K) • 53 18 ~G Thermodynamic Properties of 02 and H 0 (298°K). 54 2 vii Table Page 19 6G for the Formation of Chloroacroleins and Chloroacrylic Acids Through Equat10ns 7 and 5 (298°K) ... .. ......... .. 55 20 Values of 6G for React10n 7 and 5 at Different Temperatures . 56 21 Values of 6G for Carbon1zation Side React10ns in Chloropropene Oxidation (298°K) . 57 viii • LIST OF ILLUSTRATIONS Illustration Page 1 Pivot Point Technique for the Screening of Catalysts in the Vapor Phase Oxidation of Chloropropenes . 9 2 Chloropropene Oxidation Apparatus . 12 3 Primary Reactions in Chloropropene Oxidation Process . 58 1 • I. INTRODUCTION 1,2 Dichloropropane (POc) is a fairly large volume by- product from Dow's glycerine and propylene oxide operations. PDC is also produced in the allyl chloride synthesis pro cess . PDC has no market value and is bang used as a feed to carbon tetrachloride plants . PDC has been dehydrochlorinated to allyl chloride (I) in accordance with the following equation : CH39HCHz-? CH2=CHCH2Cl.CH3CH=~HC1.CH39=CH2+HCl CICl Cl I II - III Liquid phase dehydrochlorination produces 1 and 2 Chloro- propenes (11.111) which have no market value. Thermal and catalytic vapor phase dehydrochlorination processes have also been examined. The catalytic process suffers from excessive coking of the catalysts which rapidly decreases the catalytic activity. Despite the high temperature required , the thermal cracking of PDC appears to be the best choice for producing allyl chloride and chloropropenes . The PDC cracking catalysts studied to date produce an excessive amount of coking which would cause process yields to decrease with time in addition to creating a reactor cleaning problem. 2 The thermal cracking of PDC produces the following compounds listed in Table 1. TABLE 1 Pyrolysis Products of 1, 2 Dichloropropane (500°C) Compound Boiling Point (l-atm) allyl' chloride 45.0 l - cis-chloropropene 32.8 l-trans-chloropropene 37.4 2-chloropropene 22 . 7 1,2 dichloropropene 77.0 Of these compounds the 1,2 dichloropropene could easily be separated from the mixture . Allyl chloride could be separated from the lighter boiling 1- and 2-chloropropenes . With further purification the allyl chloride could then be sold. The mixture of chloropropenes would be difficult to separate and a use for this product mixture which would avoid the separation problem would be attractive. Separation of Chloropropenes The light boiling chloropropenes could be separated by distillation. Howeve~ chloropropenes tend to polymerize above 70°C creating the possibility of plugging problems in the distillation tower . The solubilities of the chloropropenes as shown in Table 2 rule out liquid-liquid extractions. 3 TABLE 2 Solubilities of Light Boiling Chloropropenes Compound Water Alcohol Ether Benzene Acetone Chloroform l - cis- chloropropene i s s s s l - trans- chloropropene i s s s s 2- chloropropene i s s s s All of the organic phases are solu~ in each other preventing a partition between two phases . The chloropropenes could be separated by a cryogenic fractional crystalli zati on . The melting pOints of the chloropropenes are given in Table 3 . TAB LE 3 Melting Points of the Chloropropenes Compound Melting Point l - cis- chloropropene