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Lecture

Catalyst Synthesis II: Deposition and Precipitation

In course

ChE-410: Catalysis for emission control and energy processes

The course is an introduction to heterogeneous catalysis for environmental protection and energy production. It focuses on catalytic exhaust gas cleaning as well as gaseous and liquid fuel production. The course content is intensified in experimental exerc ...

Description

This lecture covers the principles of catalyst synthesis through deposition and precipitation, focusing on adjusting pH, reducing solvated metals, and ligand removal. It explores applications, pros & cons, (co-)precipitation, nucleation, crystal growth, and various catalyst supports like zeolites and carbon. The lecture also delves into the advantages, limitations, and applications of zeolites, discussing their chemical structure, synthesis, and acidity. Additionally, it presents examples of carbon as a catalyst support, including carbon nanotubes and zeolites, and a case study on Fe-ZSM-5 for NOx reduction. The lecture concludes with a discussion on sol-gel based materials and perovskites.

Instructor

Oliver Kröcher

Official source

Related concepts (32)

Acid

An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the proton donors, or Brønsted–Lowry acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents.

Vacuum deposition

Vacuum deposition , also known as vacuum coating or thin-film deposition, is a group of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface. These processes operate at pressures well below atmospheric pressure (i.e., vacuum). The deposited layers can range from a thickness of one atom up to millimeters, forming freestanding structures. Multiple layers of different materials can be used, for example to form optical coatings.

Physical vapor deposition

Physical vapor deposition (PVD), sometimes called physical vapor transport (PVT), describes a variety of vacuum deposition methods which can be used to produce thin films and coatings on substrates including metals, ceramics, glass, and polymers. PVD is characterized by a process in which the material transitions from a condensed phase to a vapor phase and then back to a thin film condensed phase. The most common PVD processes are sputtering and evaporation.

Nucleation

In thermodynamics, nucleation is the first step in the formation of either a new thermodynamic phase or structure via self-assembly or self-organization within a substance or mixture. Nucleation is typically defined to be the process that determines how long an observer has to wait before the new phase or self-organized structure appears. For example, if a volume of water is cooled (at atmospheric pressure) below 0 °C, it will tend to freeze into ice, but volumes of water cooled only a few degrees below 0 °C often stay completely free of ice for long periods (supercooling).

Evaporation (deposition)

Evaporation is a common method of thin-film deposition. The source material is evaporated in a vacuum. The vacuum allows vapor particles to travel directly to the target object (substrate), where they condense back to a solid state. Evaporation is used in microfabrication, and to make macro-scale products such as metallized plastic film. Evaporation involves two basic processes: a hot source material evaporates and condenses on the substrate. It resembles the familiar process by which liquid water appears on the lid of a boiling pot.

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