Transcript Felles grunnlag:

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
Topic 2: Materials
Topic 3: Characterization
Topic 4: Kinetics
Topic 5: Activity measurements
Topic 6: Deactivation
Wed Sep 10 13:15 -(K24)
Wed Sep 10 13:15 -(K24)
Wed Sep. 17 14:15- (K5-323)
Tue Sep. 23 13:15- (K5-323)
Wed Sep. 24 14:15- …(K24)
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)
Essay
• 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!!
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 … (K5201)
– Wednesday November 19 13:15… (K5201)
• Exam: Dec. 3