tkp2 heterogen katalyse vk heterogeneous catalysis advanced course purpose: specialization in...
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TKP2 Heterogen katalyse VK
Heterogeneous Catalysis Advanced Course
• Purpose: Specialization in Heterogeneous Catalysis• Goal: Prepare the students to
– Learn more about (heterogeneous) catalysis– Understand and assess reported experimental work– Plan and interpret own experiments– Provide training in reporting
• Involving– Knowledge of theory, and theoretical limitations– Knowledge of practical methods – Training in presentation (written and oral)
• Expected effort:– 3,75 STP, i.e. approx. 1/8 semester, or 120 hours– < 10 hours lectures– Main part: Own studies, work with projects (vide infra) and preparation for exam
• Assessment: Oral examination + excercise (written + oral part)
Seminars/topics/dates• Topic 1: Introduction Wed Sep 10 13:15 -(K24)
• Topic 2: Materials Wed Sep 10 13:15 -(K24)
• Topic 3: Characterization Wed Sep. 17 14:15- (K5-323)
• Topic 4: Kinetics Tue Sep. 23 13:15- (K5-323)
• Topic 5: Activity measurements Wed Sep. 24 14:15- …(K24)
• Topic 6: Deactivation Wed Sep. 24 14:15- …(K24)
Heterogeneous catalysis
• Different disciplines or points of view:– Kinetics (Reaction engineering)
– Materials and synthesis (Inorganic chemistry)
– Characterization (and detailed understanding, mechanism) (Instrumental analysis, surface science)
• Catalysis can (must!) be studied at several levels:– Microscopic (atomic level)
– Mesoscopic (nano-micrometer level)
– Macroscopic (reactor -process level)
Common fundament: • General chemistry, inorganic chemistry• Chemical Reaction Engineering and earlier
subjects (including ”Prosessteknikk” (Intr. Chem.Eng.) and Physical Chemistry):– Mass- and energy balances, kinetics, reactor design– In particular Chem. Reaction Engineering (Textbook:
Scott Fogler) Chap. 10: catalysis, definitions, rate, rate limiting step (rds)
• Reaction kinetics and catalysis– Emphasis on heterogeneous catalysis
Basics
• Definition: – A catalyst increases the rate of a (desired) chemical
reaction without being consumed in the reaction– Does not influence the equilibrium
• Terms– Activity, selectivity, life-time– Classification according to type of material
• Reaction rate – Defined for different units (based on catalyst volume,
weight, total area, specific area, turnover)– global, local rate (intrinsic rate)
Continued...
• Mechanisms– Elementary steps– Rate determining reaction step (rds) – PSSA
• Adsorption amd desorption– Physical adsorption, chemisorption – Lennard Jones-diagram, heat of adsorption, activation
energy– isotherms (Langmuir, etc.)
• Chemisorption and determination of dispersion of supported metal catalysts
Continued further...
• Catalytic mechanisms
– Adsorption, desorption rate determining• E.g. NH3-synthesis (adsorption, applying the Temkin isotherm)
– Surface reaction is rds• Power rate law, LH, LHHW• Bimolecular reactions (LH, Eley-Rideal, Mars - van Krevelen)
– Temperature dependancy, activation energy, heat of adsorption
• Mass transport– diffusion (bulk, Knudsen)
– diffusion and reaction, effectiveness factor, Thiele modulus
– particle external mass transfer limitations
– all those above linked to kinetics
Still continuing….
• Catalyst deactivation– Different deactivation mechanisms
• Catalyst materials– metals, oxides, zeolites…
• Activity-selectivity-lifetime measurements (”catalyst testing”)– Laboratory reactors
Some of these topics were given only a brief treatment previously and are also included here
Teaching and curriculum • Contents summarized in lectures/seminars :
– Materials– Characterization– Kinetics– Transport/testing– Deactivation
• Curriculum literature– Slides, textbooks, papers etc.
• Individual excercise – Each student gets a journal article on catalysis to study carefully– 2 parts to the excercise:
1. Write an essay discussing the fundamental theory and practice of catalysis in the article. See next slide for points to be included.
2. Present the content of the article in a scientific presentation (for the rest of the group)– pretend to be the author of the paper!
– Both parts will count towards the mark in the course (30% of the module)
• Read the article carefully and write a report (essay) describing carefully – including the key theory (equations and assumptions) and practical issues (how are the experiments done), covering:– Which chemical reaction is studied, the background (why is it interesting),
thermodynamics (heat of reaction, equlibrium) – Type of catalyst (material, form)– If catalyst materials are prepared: Preparation and material issues– Characterization
• surface area and porosity• structure and morphology• Dispersion
– How are the activity measurements done (reactor, experimental plan), calculations, how is deactivation handled etc.
– If necessary (e.g. something unclear) gather further information from the references in the paper or other sources.
• Sometimes experimental details are given in earlier papers by the same authors.
– Do not focus on the scientific findings!!
Essay
Presentation
• Prepare and perform an oral presentation of the article you have been given– Pretend you are the scientist (PI) behind the work– Give a scientific presentation
• Background • Methods• Theory• Results and discussion• Conclusions
– Be prepared to answer questions about the methods used in the paper
Suggested dates and deadlines
• Hand in essay: Monday November 3• Seminar(s) with presentations:
– Tuesday November 18 13:15 … (K5-201) – Wednesday November 19 13:15… (K5-201)
• Exam: Dec. 3