Lecture 3 - Reactors

Question 1

What is based off the design of a reactor

Answer 1

The entire ECONOMY of any PROCESS

Question 2

What is the primary goal of a reactor

Answer 2

• To improve process intensification, energy efficiency, and overall process performance which leads to reduced capital and operational costs, smaller equipment
  footprint, and improved safety due to fewer connections and handling of hazardous
  materials

Question 3

What are the types of reactions

Answer 3

1. Synthesis or direct combination of substrates/reactants
2. Decomposition of compounds (thermolysis, electrolysis and photolysis processes possible)
3. Substitution or Single displacement reaction - one functional group in a chemical compound is replaced by another functional group (nucleophilic, electrophilic and free
   radical reactions )
4. Double displacement or metathesis – most common is precipitation reactions, neutralization reactions. Grubbs catalyst, a ruthenium-based compound, is used in olefin
   metathesis reactions to create new carbon-carbon double bonds

Question 4

Explain reations and heat

Answer 4

• Reactions can be exothermic or endothermic
• A process can: absorb energy ( in the form of heat ) or release energy (in the form ofheat / light / sound)
• Spontaneity - ΔH is negative and ΔS is positive (keep in mind ΔG)
• It is important!! to be able to control heat in a reactor system
• For removal: Cooling Jackets or Coils,
• For addition: Electric Heaters, (commonly used in laboratory-scale reactors), Steam or Hot Oil Jackets

** The choice is dependent on the type of reaction, the scale of the reactor, the required temperature control, and safety considerations

*** T control - ensures the desired reaction rate, selectivity, and product quality devoid of undesirable side reactions or hazards due to excessive heat

Question 5

What are the steps in Alkene hydrogenation

Answer 5

• Adsorption
• Activation
• Chemisorption
• Hydrogenation
• Desorption
• Regeneration

Question 6

Explain all the steps in alkene hydrogenation

Answer 6

• Adsorption: Hydrogen molecules are adsorbed onto the surface of the catalyst
• Activation: The hydrogen molecules on the catalyst surface are activated, often by breaking the H-H bond
• Chemisorption: The alkene molecules chemisorb (bond) onto the catalyst surface
• Hydrogenation: Hydrogen atoms from the activated hydrogen molecules add to the alkene’s carbon atoms, breaking the double bond and forming a single bond between the carbon atoms
• Desorption: The hydrogenated alkane product desorbs from the catalyst surface
• Regeneration: The catalyst may require regeneration by removing any adsorbed reactants or products before it can be used for further hydrogenations

Question 7

Explain Reaction rates

Answer 7

• Need to know how fast a reaction proceeds (product formed or reactant consumed per
  given time)
• Reaction rate can significantly impact the efficiency, selectivity, and safety of the process

Question 8

What are things to consider for reaction rates in reactors

Answer 8

• Reaction Kinetics
• Temperature effectse
• Pressure Effects
• Concentration, catalysts
• Reactant mixing
• Residence time
• Inhibitors and side reactions
• Safety

Question 9

Explain Reaction Kinetics

Answer 9

Determination of the optimal conditions for achieving the desired conversion of reactants into products

Question 10

Explain Temperature effects

Answer 10

In general, raising the temperature increases rate, therefore reactor design should consider the need for heating or cooling for the desired T

Question 11

Explain Pressure Effects

Question 12

Explain Concentration, catalysts

Answer 12

Can enable the use of milder conditions

Question 13

Explain Reactant mixing

Answer 13

Poor mixing can lead to uneven reaction rates and incomplete conversions

Question 14

Explain Residence time

Answer 14

The residence time should be optimized to achieve the desired level of conversion

Question 15

Explain Inhibitors and side reactions

Answer 15

Consideration should be given to the presence of inhibitors
or potential side reactions that can slow down the desired reaction or produce undesired
byproducts

Question 16

Explain Safety

Answer 16

Incorporate safety features to prevent such incidents, including pressure relief
systems and temperature control mechanisms

Question 17

What do New reactor concepts represent

Answer 17

A diverse range of technologies and applications

Question 18

Explain New reactor concepts

Answer 18

• Aim – to address various challenges such as energy sustainability, environmental protection, and space exploration
• Ongoing research and development efforts continue to refine and expand these concepts, to achieve greater
  efficiency, safety, and
  sustainability in various industries
• Reactor types :
  1. Multifunctoanl reactors - are
  innovative chemical reactors that combine multiple functions or unit operations within a single vessel

**Examples include mixing, reaction, separation, and heat exchange etc.