Reaction kinetics in formulated industrial catalysts By Sam K. Wilkinson A thesis submitted to the School of Chemical Engineering of the University of Birmingham for the degree of DOCTORATE IN ENGINEERING EngD School of Chemical Engineering Faculty of Engineering The University of Birmingham B15 2TT, UK University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. Abstract In heterogeneous catalysis, a fundamental understanding of the necessary physico- chemical requirements for a catalyst formulation is essential to its success, both in terms of performance and longevity. Understanding of reaction kinetics via modelling is essential for fundamental understanding of how catalysts work, providing functional information around surface active sites and details of reaction mechanism. This tool, combined with well- designed laboratory experiments to test a catalyst under steady and/or non-steady state conditions, can provide insight into the links between catalyst formulation and reaction performance. The aim of this project is to develop novel strategies and methods in these areas utilising a range of Johnson Matthey catalysts and reaction systems. This thesis places significant focus on obtaining mechanistically and statistically sound kinetic models with reliable model parameter estimates. Methods for this are developed using a batch liquid phase hydrogenation system using a Pt/TiO2 catalyst and are subsequently applied throughout the thesis. Non-steady state analysis of catalyst formulations has been explored successfully under a number of distinct situations. Kinetic analysis of the initial transient behaviour of a fresh vanadium phosphorus oxide selective oxidation catalyst under reaction conditions was highly effective at understanding the evolution of distinct active site populations on the catalyst surface with time on stream. A subsequent study of copper-based methanol synthesis catalysts explored the impact of gas phase conditions on the catalyst state. A mixture of steady-state testing and transient response experiments (i.e. via an imposed change in gas phase conditions over the catalyst) provided not only a robust and mechanistic kinetic model for catalyst performance but also new insights into the evolution of active site populations and populations of surface species on the catalyst surface. Overall, the reaction kinetics studies demonstrated across this thesis demonstrate not only a series of methods to understand catalyst behaviour in greater depth but also to understand the key functional requirements for an effective industrial catalyst. 1 Acknowledgments The four years of my EngD project with the University of Birmingham and Johnson Matthey has been a fantastic experience and (steep) learning curve for me in the field of reaction engineering and research in general. I’d firstly like to acknowledge my supervisors Prof. Mark Simmons, Dr. Mike Watson, Prof. Hugh Stitt and Dr. Phil Robbins.: Firstly Mark, a huge thank-you for the boundless support you have given me in all aspects of my work during the doctorate. You’ve always gone the extra mile for me with the project and I also appreciate the critical eye you’ve given to my written work and presentations. Many good memories – particularly the wine and poster session at JMAC 2012…although the next day was a little difficult! Mike – the ideas and premise you provided to my project were great and laid the foundations for an exciting set of studies. I also greatly appreciate the support you have given me during the project and in integrating into the Catalyst Research group at JMTC-North. Thanks also for the excellent tutelage I have received from you in catalysis and chemistry – many aspects of both were largely a blank slate for me when I first began my project here. Hugh – the enthusiasm and ideas you have brought to my project have been fantastic. I’ve really enjoyed the in-depth scientific discussions we have (often running till late on a Friday afternoon or over a few beers!) I also appreciate the wider opportunities you have given me within my project at JM and with the reaction engineering conferences I have attended. Many good memories, particularly of meetings filled with puns (I can see Mike holding his head in despair!) and frequent quotations of the Yorkshireman’s 2nd Law of Thermodynamics (‘ye don’t get ‘art fer nart’) Thanks also to you Phil for you help in my project. I’ve always enjoyed working with you, going back to my undergrad days and it was good to have you around for my EngD reviews and to check over my written work! A big thank-you also to Dr. Richard Greenwood (EngD co-ordinator in the Centre for Formulation Engineering). Cheers Richard for doing a stellar job in running the EngD programme and thanks for enabling me to attend three international conferences! I have some great memories of the quarterly EngD reviews in Birmingham and Teesside interchanging between legendary currys and the Wynyard! On a day-to-day basis I had the fortune of working with Drs Xavier Baucherel, Leon van de Water and John West (all at JM). Xavier – thanks for the support you gave me in the early stages of the project and you help in getting my experimental work going. We certainly had some (frustrating!) challenges on the VPO rig but it was all worth it in the end! Leon – working with you on the methanol synthesis project has been fantastic; I’ve always enjoyed how we’ve combined a passion for the topic with plenty of jokes at the same time. I also appreciated all of the chemistry and in-depth catalysis I’ve learnt off you – Dank je wel! John – thanks for all of your help and training on my thermal analysis work and for the flexibility in building in my experiments to your setup. I thoroughly enjoyed the 3 months we worked together on the ammonia SCR project! 2 I also extend a big thanks to many of my friends who have supported me over the past four years. Pete (Clark) – cheers for being a great housemate over the past two years – hopefully we’ve kept each other sane enough to get through our respective EngD endeavours – good luck over the rest of your project. Iain (Hitchcock) – always enjoy our big scientific discussions, long may they continue! Michele (Marigo) – as a fellow EngD, always good to talk to you about the project, the future and ‘massive’ ideas, with a good dose of banter thrown in! Jeroen (ten Dam) – great memories from our thesis weekends, particularly with the rewards for (completing) some work in the form of club sandwiches and Belgian beer! Lockhart (Horsburgh) for our countless discussions about heavy metal, cheese and pub quizzes! Also thanking Dilip (Poduval), my office ‘neighbour’ for three years and the many cricket matches and concerts we’ve been to. I’d also like to mention the friendship of my undergraduate/school friends Jon Blake, Robert Osborne, Rebecca Sindall, Richard Webster, Sam Lythe and Robert Wright over the years, cheers. Thanks to all of my other friends who have supported me as well – you know who you are! Last but not definitely not least, thank you to my loved ones for your endless support and patience throughout my doctorate – my girlfriend Lou, mum Michele, step-dad Alan and grandparents Ken and Sylvia. You guys have played a huge part in supporting me in getting to where I am today! I am also indebted to the specific contribution of the following individuals to the results chapters: Chapter 3: Prof. Chris Hardacre, Dr. Jillian Thompson, Dr. Helen Daly, Ian McManus (Queen’s University Belfast) for the background work and experimental data generated which were utilised in this chapter. Nazita Sedaie Bonab (University of Birmingham) whose PhD work on this topic ran in parallel to my work in this chapter. Jeroen ten Dam (JM) – many thanks for your insight on catalytic hydrogenation chemistries and some fantastic discussions over a coffee or three! Chapter 4: Dr. Xavier Baucherel (JM) Dr. Richard Smith (XPS analysis and interpretation) (JM) – it was great to understand the workings of this technique from you and many thanks for your help in designing some very interesting XPS experiments on this system, the results of which go much further than presented in this chapter. Malcolm Kett (XRD and Raman Spectroscopy experiments) (JM) 3 Rob Fletcher (Mercury porosimetry and BET surface area experiments) (JM) Colin Baptist (JM) – the rig gas chromatograph and I are very thankful to your help at times of crisis! Chapter 5: Dr. Andy York (JM) – your idea to look at the ‘start-up’ of these selective catalytic reduction catalysts was an excellent one and led to a fascinating project. Thanks for the support and dicussions we have had. Dr. Jörg Münch (JM) – many thanks for the experimental catalyst testing data and full support on this work. Dr. John West (JM) Dr. Iain Hitchcock (BET surface area experiments and analysis) (JM) Malcolm Kett (XRD and Raman Spectroscopy experiments) (JM) Chapters 6 and 7: Dr. Leon van de Water (JM) Colin Ranson (N2O reactive titration experiments and for providing background property data to the catlaysts tested) (JM) Rob Fletcher (BET surface area experiments) (JM) Sam K. Wilkinson – February 2014 4 Table of contents Chapter 1: Reaction kinetics in formulated industrial catalysts: Introduction and business case 1.