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Catalytic Hydroconversion of Diphenylmethane with Unsupported Mos2

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Catalytic Hydroconversion of Diphenylmethane with Unsupported Mos2 Catalytic Hydroconversion of Diphenylmethane with Unsupported MoS2 by Ross S. Kukard B.Sc. Eng. Chem. (hons), The University of Cape Town, 2006 M.Sc. Eng. Chem., The University of Cape Town, 2009 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Chemical and Biological Engineering) The University of British Columbia (Vancouver) September 2014 © Ross S. Kukard, 2014 Abstract The mechanism by which hydroconversion catalysts promote residue conversion and coke suppression is unclear. Several theories are proposed in the literature but these have all been opposed, usually due to their lack of controlled mechanistic studies. A promising catalyst for residue hydroconversion is unsupported MoS2. This catalyst is effective but expensive and deactivates during the reaction. Model compound studies were needed to elucidate the mechanism of MoS2 catalysis in hydroconversion reactions, how this relates to residue hydroconversion and hence propose deactivation mechanisms and regeneration methodologies. Model compound screening in a commercially available stirred slurry-phase batch reactor identified diphenylmethane (DPM) as a suitable model reagent. Ex- periments were conducted at industrially applicable conditions of 445◦C, 13.8 MPa H2 and catalyst loadings of 0 - 1800 ppm Mo (introduced as Mo octoate which formed the MoS2 active phase in-situ). Slow heat-up rates and wall catalysis, how- ever, made this reactor unsuitable for detailed mechanistic studies. A novel mixed slurry-phase micro-reactor system was designed using externally applied vortex mixing and removable glass-inserts to allow for greater analytical resolution and determination of the thermocatalytic mechanism. Deactivated MoS2 catalysts, as coke-catalyst agglomerates recovered from residue hydroconversion studies [1], were evaluated using the DPM testing methodology and a deactivation mechanism proposed. It was determined that the unsupported MoS2 crystallites hydrogenate the DPM feed to cyclohexylmethylbenzene (CHMB) which undergoes thermolysis to short chain hydrocarbon radicals. These short chain radicals stabilise, by radical addi- tion or radical disproportionation, other radicals in the system by a chain stabili- ii sation reaction, itself promoted by catalytic hydrogenation (for instance of olefins formed during disproportionation). Deactivation of unsupported MoS2 in residue hydroconversion was proposed to be due to the formation of an unreactive, porous carbonaceous structure upon which the otherwise unaltered catalyst particles be- come supported. The pores physically exclude larger species, such as asphaltenes, from reaching the active sites. Inter-recycle solvent extraction to remove coke precursors was proposed to in- hibit deactivation in residue hydroconversion whilst mechanical and chemical size reduction were suggested for breaking the porous structure and re-exposing the MoS2 crystallites. iii Preface All of the work presented henceforth was conducted in the Department of Chemi- cal and Biological Engineering at the University of British Columbia, Point Grey campus. I, Ross S. Kukard, was the lead investigator of this work, responsible for all major areas of concept formation, micro-reactor design, construction and commis- sioning and all experimentation, data collection and analysis as well as preparation of this thesis. Kevin J. Smith was the supervisor of this research, involved through- out the project in concept formation and thesis edits. Hooman Rezaei commis- sioned the stirred batch reactor described in Section B.2.1 which I used to conduct the experiments and collect the data in Section 4.1. He also conducted the residue hydroconversion experiments to generate deactivated catalyst samples and compar- ison data (Section 4.2.3). The mechanical workshop in the Department of Chemi- cal and Biological Engineering, led by Doug Yuen, constructed the micro-reactor enclosures described in Section B.3.1 using designs that I prepared. I presented data from Section 4.1 at the 62nd Canadian Chemical Engineer- ing Conference (Vancouver, BC, Canada), 2012 and data from Section 4.2 at the 23rd Canadian Symposium on Catalysis (Edmonton, AB, Canada), 2014. Kevin J. Smith was involved in the preparation of these presentations. iv Table of Contents Abstract.................................... ii Preface .................................... iv TableofContents .............................. v ListofTables................................. xi List of Figures . xiii Nomenclature ................................ xx Acknowledgements ............................. xxix Dedication .................................. xxx 1 Introduction ............................... 1 2 LiteratureReview ............................ 5 2.1 Current Hydroconversion Technology . 5 2.2 Residue Processing Technologies . 6 2.2.1 Carbon Rejection . 7 2.2.2 Hydroconversion ...................... 8 2.2.3 Slurry-Phase Catalytic Hydroconversion . 10 2.3 Catalyst Testing . 12 2.3.1 Heavy Oil and Residue Oil Studies . 12 v 2.3.2 Model Compound Studies . 13 2.4 Micro-Reactors for Catalyst Testing . 16 2.4.1 Advantages and Disadvantages of Micro-Reactors . 16 2.4.2 Micro-Reactors in Hydroconversion Studies . 17 2.5 Catalyst Activity and Deactivation . 18 2.5.1 Catalyst Selection . 19 2.5.2 Molybdenum Disulphide . 20 2.5.3 Processes of Deactivation . 26 2.5.4 Catalyst Regeneration Methodologies . 28 2.6 Summary of Findings from the Literature . 29 3 Experimental............................... 30 3.1 Experimental Objectives and Programme . 30 3.1.1 Interpretation of Questions to Objectives . 31 3.1.2 Experimental Programme . 35 3.2 Experimental Apparatus and Supplies . 39 3.2.1 Reaction and Analytical Supplies . 39 3.2.2 Reactors and Conditions . 40 3.3 Analytical Equipment and Data Analysis . 53 3.3.1 Gas Product Analysis . 53 3.3.2 Liquid Product Analysis . 54 3.3.3 Solid Product Analysis . 54 4 ExperimentalResults .......................... 55 4.1 Stirred Batch Reactor . 55 4.1.1 Model Compound Screening . 55 4.1.2 Benzene, Toluene and Decalin Blanks . 59 4.1.3 Diphenylmethane Studies . 60 4.2 BatchMicro-reactor......................... 83 4.2.1 Inclined Stainless Steel Micro-Reactor . 83 4.2.2 Vertical Stainless Steel Micro-Reactor . 88 4.2.3 Glass Insert Micro-Reactor . 101 vi 5 DiscussionofExperimentalResults . 140 5.1 Model Compound Evaluation . 140 5.1.1 Model Compound Screening . 140 5.1.2 Diphenylmethane Studies . 142 5.1.3 Summary of Model Compound Evaluation . 155 5.2 Novel Reactor System Design and Testing . 157 5.2.1 Inclined Stainless Steel Micro-Reactor . 158 5.2.2 Vertical Stainless Steel Micro-Reactor . 162 5.2.3 Unmixed Glass Insert Micro-Reactor . 169 5.2.4 Mixed Glass Insert Micro-Reactor . 171 5.2.5 Summary of Micro-Reactor System Design and Testing . 183 5.3 Catalyst Study and Deactivation Investigation . 185 5.3.1 Active MoS2 ........................ 185 5.3.2 Deactivated Coke-MoS2 Agglomerate . 187 5.3.3 Mechanism of MoS2 Deactivation in Residue Hydrocon- version ........................... 192 5.3.4 Summary of MoS2 Activity and Deactivation . 195 6 Conclusions................................ 197 References .................................. 201 Appendices .................................. 218 A Catalyst Deactivation and Regeneration . 219 A.1 Processes of Catalyst Deactivation . 219 A.1.1 Fouling ........................... 219 A.1.2 Poisoning.......................... 222 A.1.3 Others............................ 227 A.2 Catalyst Regeneration Processes . 230 B Experimental Apparatus and Procedures . 233 B.1 Detailed Experimental Programme . 233 B.2 Batch Reactor Specifications and Operation . 234 vii B.2.1 Description and Specifications . 241 B.2.2 Operating Procedure . 244 B.2.3 Safety Considerations . 255 B.3 Micro-Reactor Design, Development and Operation . 257 B.3.1 Design and Development . 257 B.3.2 Operating Procedure . 276 B.3.3 Safety Considerations . 287 C Analytical Apparatus, Procedures and Data Analysis . 289 C.1 GasProductAnalysis . 289 C.1.1 Analytical Equipment and Procedures . 289 C.1.2 Calibration, Data Acquisition, Analysis and Interpretation 292 C.2 Liquid Product Analysis . 296 C.2.1 Analytical Equipment and Procedures . 296 C.2.2 Data Acquisition, Analysis and Interpretation . 301 C.2.3 Calibration, Analysis and Experimental Uncertainty . 307 C.3 Solid Product Analysis . 318 C.3.1 Analytical Equipment and Procedures . 318 C.3.2 Calibration, Data Acquisition, Analysis and Interpretation 320 D CalibrationData............................. 333 D.1 GasChromatograph......................... 333 D.1.1 HP5980A Calibration Results . 333 D.1.2 Shimadzu GC-14B Calibration Results . 333 D.2 GCMS-QP2010 Gas Chromatograph - Mass Spectrometer Liquid Calibration Results . 335 D.2.1 Benzene........................... 335 D.2.2 Toluene........................... 337 D.2.3 Diphenylmethane . 339 D.2.4 Diphenylethane . 341 D.2.5 Diphenylpropane . 343 viii E DetailedExperimentalResults . 345 E.1 Stirred Batch Reactor . 345 E.1.1 Model Compound Screening . 345 E.1.2 Diluted Diphenylmethane . 346 E.1.3 Undiluted Diphenylmethane . 347 E.2 Stainless Steel Batch Micro-reactors . 356 E.2.1 Inclined Stainless Steel Micro-Reactor . 356 E.2.2 Vertical Stainless Steel Micro-Reactor . 356 E.3 Glass Insert Batch Micro-reactor . 356 E.3.1 Comparison with Stainless Steel Micro-Reactor . 356 E.3.2 Visual Mixing Studies . 356 E.3.3 Comparison of Liquid Loading Volumes . 356 E.3.4 Thermocouple Wall
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