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Lecture 1-2 Topics to be covered: Importance of Subject Catalysis: Introduction of Catalysis, Classification of catalysts, Types of catalysts, Mode of action of catalysis, Mechanism of catalytic reaction Importance of catalysis in chemical and allied industries.

Basic difference between CRE-I and CRE-II, is that in CRE-I we have dealt with only homogeneous systems of reaction where as in CRE-II the heterogeneous system will also be incorporated. Because of heterogeneity, for the rate of reaction we need to consider following aspects

Ø Overall rate of reaction Ø Equilibrium solubility Ø Contacting Pattern

We will develop the rate expression for Gas Liquid reaction, which will be applicable to Liquid-Liquid system as well. Based on the rate of reaction and the diffusion resistance there will be total nine different possible cases. Chemical reactions are the base of Chemical Engineering which offers the millions of different materials. Some Industrially important reactions and reactors will be discussed. The fundamentals of Catalyst will be discussed like What are they? What are they doing? How do they look like? How to apply? What for? How catalysts speed up the rate of reaction? Mechanism of catalytic reaction, role of promoters, support etc. Industrial applications of Catalysts.

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Catalysis: Applications • Environment / Health

– Three-way Catalyst - Pt/Rh/Al2O3 » CO + NO + HC CO2 + H2O + N2

• Chemicals / Refinery – 80-90% products produced through catalysis

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Lecture 3-4 Topics to be covered: Catalyst Materials, Properties and Preparation Catalyst Materials: Introduction, Catalyst materials: Makeup of a typical heterogeneous catalyst, Active phase, carriers, promoters and additives

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Lecture 5-6 Topics to be covered: Catalyst properties: Physical and mechanical properties, their definition and their importance, Chemical Properties, Dynamic properties Catalyst properties can be classified as physical, chemical and dynamic. Physical properties include surface area, pore structure, density and mechanical properties such as crush strength. Chemical properties include the chemical state of the active catalyst phase, acidity and surface composition and structure. Dynamic properties focus on catalyst behavior during reaction, i.e. catalytic properties including activity and selectivity. An understanding of the relationships among chemical, physical and catalytic properties i.e. structure-activity relationships constitutes a basis for rational design of catalysts.

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Triangular concept for catalyst design

Physical and mechanical Properties: Definitions and Specifications

Property Definition/Specification Density

Bulk density, ρb Mass per unit vol. of bulk catalyst, i.e. bed packed density Particle density, ρp Mass per unit vol of pellet; also called apparent density Solid density, ρs Mass per unit vol. of solid of solid; also called skeletal or

true density Pore volume, Vpore

Macropore Volume Volume of macropores per unit mass (dpore > 50 nm) Mesopore volume Volume of mesopores per unit mass(dpore of 3-50 nm) Micropore volume Volume of micropores per unit mass(dpore < 3 nm)

Pore size and size distribution Macropores Average size (diameter) and distribution for dpore> 50 nm Mesopores Average size (diameter) and distribution for dpore of 3-50 nm Micropores Average size (diameter) and distribution for dpore < 3 nm

Surface area, Sint Meso and macropore SA

SA of pores with diameter of 3- 5000 nm.

Micropore surface area SA of pores with diameter of less than 3 nm. Active site concentration of SA, Scat

Number of active sites per mass of catalyst or active SA

Catalyst particle size Diameter and/or length of pellets/extrudates or hole size (pitch) of monoliths

Crushing strength Particle Force necessary to crush particle in axial or radial direction Bulk Displacement or percentage of fines versus hydraulic

pressure Attrition Percentage loss per time due to formation and loss of fines

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Chemical Properties: Definitions and Specification

Property Definition/specification Acidity Brønsted acidity Ability of a material to donate protons Lewis acidity Ability of a material to capture electrons Chemical composition Chemical make-up by element Bulk Surface Oxidation state Chemical state or valence state Bulk Surface Chemical structure Geometric arrangement of atoms, arrangement properties of

electrons and bonding characteristics of atoms Bulk Surface Dynamic (Catalytic) Properties of Catalysts: Definitions and Specifications

Property Definition/ Specification Intrinsic specific activity

Specific reaction rate based on surface area or number of sites measured in the absence of heat/mass transport and deactivation disguises at specifies T, P and conversion

Turnover frequency Molecules converted pr produced per catalytic site per second Specific rate (Sbasis) Moles converted or produced pr catalytic SA per second Catalytic activity Reaction rate or equivalent measured at specified T, Preact,

conversion Rate based on SA Rate based on catalytic surface area, intrinsic or nonintrinsic Rate based on mass, volume

Rate based on catalytic mass or volume, intrinsic or nonintrinsic

T for required conversion

Temperature for required conversion of reactants, usually nonintrinsic

T for given product quality

Temperature for specified product quality, usually nonintrinsic

Selectivity Amount or relative rate of production of specified product relative to others

Rate-based Rate of production of specified product divided by rate for another product

Production distribution- based

Percentage of specified product in total product mixture

Stability Measure of activity decline at specified conditions Deactivation rate Rate of activity loss. da/dt where a is normalized activity Resistance Inverse of deactivation rate, e.g. half-life or time to reach

specified activity Tolerance Residual activity after complete poisoning or fouling

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Lecture 7-10

Topics to be covered: Catalyst Preparation: Introduction, co-precipitation, sol-gel, citrate, ceramic, solution combustion, reactive grinding, wet impregnation, micro emulsion, flame hydrolysis etc, other novel methods for the preparation of nano-composites. 81

The development of a solid catalyst requires knowledge of the parameters which have the greatest influence on catalyst performance.

The main objective of catalyst development is optimization of the various different catalyst properties; an essential precondition for achieving such an objective is a close cooperation between experts working in very different fields of scientific research.

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Preparation of catalyst using various methods like Impregnation, Co-precipitation, Sol-Gel and Micro-emulsion will be discussed along with importance of preparation parameters with respect to activity. Preparation of solids catalysts Currently, two principal routes exist for the production of technical catalysts: The first route, yielding bulk catalysts, starts with the precipitation of a catalyst precursor, which is filtered,dried, and shaped. Calcination steps may be included after drying or after shaping. The second route starts with a carrier material, which can be impregnated with salt solutions or coated with powders. Drying and calcination give the final supported catalyst.

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Lecture 11-12

Topics to be covered: Catalyst Characterization: Introduction, Characterization of catalysts by various methods like Surface area, Pore size distribution, Chemisorption, Temperature Programmed Reduction & Oxidation, X-ray diffraction, X-ray Photoelectron Spectroscopy, Infrared Spectroscopy, Thermogravimatric analysis etc. Characterization is a central aspect of catalyst development. The elucidation of the structures, compositions, and chemical properties of both the solids used in heterogeneous catalysis and the adsorbates and intermediates present on the surfaces of the catalysts during reaction is vital for a better understanding of the relationship between catalyst properties and catalytic performance. This knowledge is essential to develop more active, selective and durable catalysts and also to optimize reaction conditions. Brief introduction about methods and importance of Catalyst Characterizations.

Detailed study of Characterizations, Interpretations and co-relations with activity enhancement of catalysts.

Ø Surface Are, Pore Size, Pore Volume Ø Dispersion, Chemical Composition Ø XRD, XPS Ø FTIR, NMR Ø SEM, TEM Ø TGA-DTA

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Catalyst characteristics and methods for their investigation Properties Characterization Techniques

Physical Properties

Density: Bulk density (tap) * Tapping pack density* Particle density (apparent) * Hg displacement* Skelton density (solid) * Hg displacement

Pycnometry*

Pore volume* Pore size*, Size distribution* Extended N2 & CO2 adsorption*

Hg porosimetry* NMR spin Relaxation of H2O

Surface area* Adsorption of N2* or CO2 (BET & Langmuir) * CCSEM

Pore size distribution* BJH (Barret, Joyner and Halenda) * Catalyst Particle size* and size distribution* Sieving*

SEM* TEM* Electronic counting* Laser light scattering* Optical Imaging*

Chemical Properties

Surface Acidity* Adsorption and TPD of bases e.g. NH3* IR* NMR*

Chemical Composition Bulk* XPS* FTIR* NMR* XRF/XRD* SEM * TEM * MAS TG* Magn.

Surface* XPS* AES SIMS EXAFS ISS

Chemical State Bulk* TGA* DTA TPR* MAbS FTIR* Magnetic method EPR NS NMR*

Surface* XPS* TPSR NMR* EXAFS MabS FTIR*

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Chemical State, Surface additives* XPS* FTIR* Raman NMR* EELS HREELS TPD TPSR* MBS

Elemental composition of catalysts* Metal Trace Analyzer / Atomic Absorption Spectroscopy*/ICP*

Homogeneity SEM TEM EPMA IMP LMMS PIXE

morphology/state: Bulk* XRD * SEM * TEM * STEM MabS

Surface TEM LEED EXAFS STEM STM FEM

Surface reactivity, active site concentration Chemisorption TPD TPSR Transient kinetic methods Calorimetry

Dispersion or percentage exposed* Chemisorption* TEM * XRD* Electron Microscopy SEM Magnetic methods Chemical methods Electron microprobe analyzer

Mechanical Properties

Single pellet crush strength Crushing test in hydraulic press* Bulk Crushing strength Crushing test in hydraulic system* Attrition and abrasion resistance Rotating Drum*

Air jet* Ultrasonic test

Thermal Properties

Coke measurement* Thermo Gravimetric Analysis*, TPO*

Electronic properties

EPR Conductivity, Semi conductivity Electron extraction work function

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Lecture 13-14 Topics to be covered: Catalyst Deactivation and Regeneration of catalysts Causes for deactivation will be discussed in the detail. The minimization for deactivation to be followed and subsequently regeneration of catalysts will be discussed.

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