Catalytic Kinetics
Catalytic Kinetics - Related Videos
08:56
Catalytic Reactor: Hydrogenation of Ethylene
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2023
Source: Kerry M. Dooley and Michael G. Benton, Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA The hydrogenation of ethylene (C2H4) to ethane (C2H6) has often been studied as a model reduction reaction in characterizing new metal catalysts.1-2 While supported nickel is not the most active metal catalyst for this reaction, it is active enough that reaction can take place at < 200°C. The reaction typically involves adsorbed, dissociated hydrogen (H2) reacting...
08:07
Enzyme Assays and Kinetics
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2023
Enzyme kinetics describes the catalytic effects of enzymes, which are biomolecules that facilitate chemical reactions necessary for living organisms. Enzymes act on molecules, referred to as substrates, to form products. Enzyme kinetic parameters are determined via assays that directly or indirectly measure changes in substrate or product concentration over time. This video will cover the basic principles of enzyme kinetics (including rate equations) and kinetic models. The concepts governing...
01:07
Catalytically Perfect Enzymes
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2023
The theory of catalytically perfect enzymes was first proposed by W.J. Albery and J. R. Knowles in 1976. These enzymes catalyze biochemical reactions at high-speed. Their catalytic efficiency values range from 108-109 M-1s-1. These enzymes are also called 'diffusion-controlled' as the only rate-limiting step in the catalysis is that of the substrate diffusion into the active site. Examples include triose phosphate isomerase, fumarase, and superoxide dismutase. Most enzymes achieve catalytic...
01:19
Turnover Number and Catalytic Efficiency
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2023
The turnover number of an enzyme is the maximum number of substrate molecules it can transform per unit time. Turnover numbers for most enzymes range from 1 to 1000 molecules per second. Catalase has the known highest turnover number, capable of converting up to 2.8×106 molecules of hydrogen peroxide into water and oxygen per second. Lysozyme has the lowest known turnover number of half a molecule per second. Chymotrypsin is a pancreatic enzyme that breaks down proteins during digestion. The...
03:07
Kinetic Molecular Theory: Molecular Velocities, Temperature, and Kinetic Energy
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2020
The kinetic molecular theory qualitatively explains the behaviors described by the various gas laws. The postulates of this theory may be applied in a more quantitative fashion to derive these individual laws. Collectively, the molecules in a sample of gas have average kinetic energy and average speed; but individually, they move at different speeds. Molecules frequently undergo elastic collisions in which the momentum is conserved. Since the colliding molecules are deflected off at different...
FAQs
A catalyst changes the available reaction pathway so the process proceeds with a lower activation energy. This can increase the reaction rate while leaving the catalyst itself unconsumed. Kinetic analysis examines how that altered pathway affects conversion and helps engineers connect catalyst behavior with the performance of chemical processes.
Reaction rate depends on variables identified through kinetic analysis, including reactant concentration, temperature, pressure, and catalyst properties. Changing these factors can alter the observed rate and may also affect the preferred reaction pathway. Engineers relate these dependencies to rate laws, which provide a quantitative basis for evaluating and controlling process performance.
Catalyst properties influence more than the speed of conversion. They can affect which reaction pathways are favored, making them important to both selectivity and productivity. In engineering design, examining these effects helps identify catalyst conditions that support the desired product while limiting inefficient operation and improving the overall process outcome.
Engineers use rate laws to express how reaction rate changes with relevant operating variables such as concentration, temperature, and pressure. These relationships support interpretation of kinetic behavior, evaluation of proposed reaction mechanisms, and reactor sizing. They also provide a structured way to compare operating conditions when designing or optimizing an industrial process.
A typical application begins by relating reaction rate to reactant concentration, temperature, pressure, and catalyst properties. Engineers then use the resulting rate laws to assess the reaction mechanism and size a reactor for the intended conversion. The same analysis can guide operating-condition optimization, linking laboratory kinetic understanding to process-scale engineering decisions.
Catalytic kinetics supports a wide range of engineering applications, including petroleum refining, chemical manufacturing, emissions control, and sustainable energy systems. In each setting, reaction-rate behavior helps determine how efficiently a process performs. The resulting kinetic understanding can influence productivity, product selectivity, energy use, and process economics.
Kinetic analysis shows how operating conditions and catalyst properties influence reaction rates and pathways. Engineers use that information to seek conditions that improve conversion and selectivity without overlooking energy requirements. Better alignment between rate behavior and process design can increase productivity, reduce energy use, and strengthen the economic performance of the overall system.