OLIGOMERIZATION OF PENTENES BY ACID ZEOLITES by ATISH KULKARNI A thesis submitted to the Graduate School-New Brunswick Rutgers, The State University of New Jersey In partial fulfillment of the requirements For the degree of Master of Science Graduate Program in Chemical and Biochemical Engineering Written under the direction of Dr. Fuat E. Celik, And approved by _________________________________________________ _________________________________________________ ________________________________________________ New Brunswick, New Jersey January, 2015 ABSTRACT OF THESIS Oligomerization of Pentenes by Acid Zeolites By ATISH KULKARNI Thesis Director: Dr. Fuat E. Celik Crude oil refining produces numerous light hydrocarbons (alkanes and alkenes). Of these, C2-C4 hydrocarbons are commercially important precursors for synthetic rubber, polymers and other chemical products. C5 hydrocarbons are unwanted by-products; they are not suitable as liquid or gaseous fuels, leading to difficulty regarding storage and handling. The present work is based on an idea to convert C5 hydrocarbons to fuels via dehydrogenation of C5 alkanes, oligomerization of C5 olefins to C10 and C15 alkenes, and further hydrogenation to fuel-grade medium molecular weight hydrocarbons. We have devised a synthesis strategy to transform the light olefins to more valuable decenes (C10 olefins), which can be used as gasoline alternatives. This transformation is termed as the oligomerization of pentene by the catalysts acid-form zeolites. Zeolites are popular catalysts for a variety of heterogeneous catalytic reactions in research as well as in the industry. The oligomerization of pentene was investigated over ZSM-5 (MFI), Beta (BEA*), Mordenite (MOR), Ferrierite (FER) and Faujasite (FAU). The primary aim is to ii achieve high activity and selectivity for oligomerization over cracking of pentenes and decenes. The effect of zeolite pretreatment, substrate concentration, reaction temperature on yield and selectivity of decenes was studied. FAU showed a promising high selectivity, so the Si/Al ratio of FAU samples was varied and a Si/Al ratio of 6 showed the greatest yield. Being acid-catalyzed, the products of the reaction are highly branched, implying higher octane ratings and therefore suitability for gasoline blending. iii ACKNOWLEDGEMENTS I would first like to thank my thesis advisor, Prof. Fuat Celik, for giving me the opportunity to work with the Celik Catalysis Group. He has shown immense support, guidance and enthusiasm throughout the course of my thesis. I would also like to thank Prof. Alan Goldman, of the Chemistry and Chemical Biology Department at Rutgers, who introduced me to the project and encouraged me to devote my thesis to it. Dr. Akshai Kumar has been with me throughout my thesis, his direction and motivation essential for every step of this project. I would like to express my sincere appreciation toward his efforts and awareness to my work. My heartfelt thanks to the other members of my thesis committee: Prof. Rohit Ramachandran and Prof. Meenakshi Dutt. I would also like to thank my colleagues in both the research groups that I have worked with for their help that was integral toward the completion of my research work. I must notably mention Longfei Chao, Yiming Yin, Deniz Dindi, Alec Hook and Ashley Pennington toward their contribution in setting up the preparatory experiments and in helping me prepare my thesis and presentation. They have been there to help and guide me at every time that I have needed them. I would like to thank a number of graduate students and friends at Rutgers, who, be it through friendship, counsel or supportive guidance have made my stay at Rutgers more wonderful and one to remember. Finally, I would like to thank my family who has been supportive and available for me throughout the course of my student life. iv TABLE OF CONTENTS Abstract ii Acknowledgements iv Table of Contents v List of Tables vi List of Illustrations vii Chapter 1 – Introduction 1.1 C5 hydrocarbons: By-Products of the Petroleum Industry 1 1.2 C10 hydrocarbons: Commercially Important Products 2 1.3 Zeolites 3 1.4 Oligomerization of Olefins 8 Chapter 2 – Experiments 2.1 Preparation of Experimental Set-up 15 2.2 Gas Chromatography Analysis and Calibration 17 2.3 Oligomerization Reaction 20 2.4 Sodium Exchange Experiment 22 Chapter 3 - Results and Discussions 3.1 Effect of Zeolite Size And Structure 25 3.2 Effect of Si/Al of FAU on Acid Strength and Acid Site Proximity 42 3.3 Catalytic Effect of Brønsted Acid Sites within the Zeolites 52 3.4 Effect of Reaction Conditions 58 Chapter 4 - Summary and Future Scope 4.1 Summary 68 4.2 Future Work 70 References 72 v LIST OF TABLES Table 1 – 1 Information for structure of zeolites 6 Table 2 – 1 Comparison of different samples of zeolites 22 Table 3 – 1 Product distribution for pentene oligomerization catalyzed by 27 MFI (Si/Al = 15) zeolite Table 3 – 2 Product distribution for pentene oligomerization catalyzed by 30 BEA* (Si/Al = 12.5) zeolite Table 3 – 3 Product distribution for pentene oligomerization catalyzed by 32 MOR (Si/Al = 10) zeolite Table 3 – 4 Product distribution for pentene oligomerization catalyzed by 34 FAU (Si/Al = 15) zeolite Table 3 – 5 Product distribution for pentene oligomerization catalyzed by 37 FER (Si/Al = 10) zeolite Table 3 – 6 Product distribution for pentene oligomerization catalyzed by 43 FAU (Si/Al = 2.6) zeolite Table 3 – 7 Product distribution for pentene oligomerization catalyzed by 45 FAU (Si/Al = 6) zeolite Table 3 – 8 Product distribution for pentene oligomerization catalyzed by 47 FAU (Si/Al = 40) zeolite Table 3 – 9 Product distribution for pentene oligomerization catalyzed by 52 Na/H-FAU (Si/Al = 6) (single exchange) Table 3 – 10 Product distribution for pentene oligomerization catalyzed by 53 Na/H-FAU (Si/Al = 6) (double exchange) Table 3 – 11 Product distribution for pentene oligomerization catalyzed by 56 fully substituted zeolite Na-FAU (Si/Al = 6) Table 3 – 12 Analysis of products for silicalite (MFI – Si/Al = 1000) and Na- 58 MFI Table 3 – 13 Product distribution for pentene oligomerization catalyzed by 59 FAU (Si/Al = 6) with varying temperature Table 3 – 14 Product distribution for pentene oligomerization catalyzed by 61 FAU (Si/Al = 6) at room temperature Table 3 – 15 Product distribution for pentene oligomerization catalyzed by 63 FAU (Si/Al = 6) with varying pentene concentration Table 3 – 16 Analysis of products for Zeolyst MFI (Si/Al = 15) and Clariant 65 MFI (Si/Al = 13.5) as catalysts as a function of time vi LIST OF ILLUSTRATIONS Figure 1 – 1 Isomers of pentene 1 Figure 1 – 2 Isomers of decene 3 Figure 1 – 3 MFI (ZSM – 5) 4 Figure 1 – 4 BEA* (Beta*) 4 Figure 1 – 5 MOR (Mordenite) 5 Figure 1 – 6 FER (Ferrierite) 5 Figure 1 – 7 FAU (Faujasite) 5 Figure 1 – 8 Reactions occur at H+ acid site 7 Figure 1 – 9 Representation of MFS framework topology 11 Figure 2 – 1 Kontes vial 20 Figure 3 – 1 Pentene oligomerization and side reactions 26 Figure 3 – 2 Effect of heating time on concentration of olefins for the reaction 28 over MFI (Si/Al = 15) Figure 3 – 3 Effect of heating time on concentration of olefins for the reaction 31 over BEA* (Si/Al = 12.5) Figure 3 – 4 Effect of heating time on concentration of olefins for the reaction 33 over MOR (Si/Al = 10) Figure 3 – 5 Effect of heating time on concentration of olefins for the reaction 35 over FAU (Si/Al = 15) Figure 3 – 6 Effect of heating time on concentration of olefins for the reaction 38 over FER (Si/Al = 10) Figure 3 – 7 Percent yield of C10 olefins as a function of heating time for 39 different samples of zeolite (Si/Al = 10-15) Figure 3 – 8 Percent selectivity toward C10 olefins as a function of heating time 40 for different zeolite samples (Si/Al = 10-15). Figure 3 – 9 Percent selectivity toward C10 olefins at around 40% conversion 41 of C5 olefins Figure 3 – 10 Effect of heating time on concentration of olefins for the reaction 44 over FAU (Si/Al = 2.6) Figure 3 – 11 Effect of heating time on concentration of olefins for the reaction 46 over FAU (Si/Al = 6) Figure 3 – 12 Effect of heating time on concentration of olefins for the reaction 48 over FAU (Si/Al = 40) Figure 3 – 13 Percent yield of C10 olefins as a function of heating time over a 50 wide range of Si/Al ratios of FAU Figure 3 – 14 Percent selectivity toward C10 olefins as a function of heating time 51 for varying Si/Al ratios for FAU vii Figure 3 – 15 Percent yield of C10 olefins as a function of heating time for H- 54 FAU and Na-exchanged FAU (Si/Al = 6). Figure 3 – 16 Percent selectivity toward C10 olefins as a function of heating time 55 for H-FAU and Na-exchanged FAU (Si/Al =6) Figure 3 – 17 Comparison of concentration of olefins observed in the products 60 as a function of temperature, after 40 minutes of heating Figure 3 – 18 Comparison of concentration of olefins observed as a function of 62 time for the reaction at room temperature over FAU (Si/Al = 6) Figure 3 – 19 Comparison of concentration of olefins observed as a function of 64 initial pentene concentration in the stock solution for the reaction over FAU (Si/Al = 6) Figure 3 – 20 Comparison of yield of olefins as a function of heating time for 66 reaction over MFI zeolite from two manufacturers – Zeolyst (Si/Al = 15) and Clariant (Si/Al = 13.5) viii 1 Chapter 1: Introduction 1.1 C5 hydrocarbons : By-products of the Petroleum Industry C5 hydrocarbons include pentanes (alkanes) and pentenes (olefins); C5 olefins are predominantly of interest for the purpose of this project.