CONTINUOUS FLOW REACTOR - WORKING PRINCIPLE, ADVANTAGES AND APPLICATIONS.pptx

Continuous flow reactors are chemical reactors where reactants are continuously fed into the system and products are continuously removed.
Continuous flow reactors provide a steady-state process that is widely used in industrial applications such as pharmaceuticals, petrochemicals and fine chemical synthesis. CONTINUOUS STIRRED TANK REACTOR (CSTR) is a type of reactor used primarily for liquid phase reactions.
It is normally operated at steady state.
It is a vessel to which reactants are added and products removed while the contents within the vessel are vigorously stirred using internal agitation or by internally ( or externally) recycling the contents.Continuous flow passes through a CSTR, both input and output streams. But not certainly at equal rates.
The mass of the system inside a CSTR is not necessarily steady.
The fluid is perfectly mixed inside a CSTR. Hence, its properties are consistent at any time because of adequate stirring.
The flow in the system may not necessarily have a constant density. The density of the inlet flow may vary among the process to reach the exit and have a different density output stream.
Provide some kind of heat transfer equipment for temperature control.
Their working principle, instrumentation, advantages, disadvantages, characteristics and synthetic applications.

1. CONTINuOUS FLOW REACTOR WORKING PRINCIPLE, ADVANTAGES AND APPLICATIONS HONEY HETTY 2 ND SEM MPHARM 2024 DEPARTMENT OF PHARMACEUTICAL CHEMISTRY ST. JAMES’ COLLEGE OF PHARMACEUTICAL SCIENCES, CHALAKUDY 1

2. CONTENTS INTRODUCTION WORKING PRINCIPLE INSTRUMENTATION CONTINUOUS STIRRED TANK REACTOR ADVANTAGES DISADVANTAGES SYNTHETIC APPLICATIONS REFERENCES 2

3. INTRODUCTION Continuous flow reactors are chemical reactors where reactants are continuously fed into the system and products are continuously removed. Continuous flow reactors provide a steady-state process that is widely used in industrial applications such as pharmaceuticals, petrochemicals and fine chemical synthesis. 3

4. Working principle Continuous feed of reactants : Reactants are continuously pumped or fed into the reactor at constant flow rate. Mixing : Thoroughly mixed to ensure homogeneity Mechanical stirring, turbulence, or flow- induced mixing All reactants are evenly distributed throughout the reactor volume Reaction : The desired chemical reaction takes place. Reaction kinectics depend on factors such as temperature, pressure and the concentration of reactants 4

5. Residence time : The time it takes for a reactant molecule to spend in the reactor, known as residence time, is crucial for determining the extent of the reaction. Residence time can be controlled by adjusting the flow rate of reactants or the volume of the reactor Product removal : The products are continuously removed from the reactor to prevent accumulation and maintain a constant volume. Continuous withdrawal from the reactor outlet or separation using downstream processes like filtration or distillation. Steady- state operation : Flow rates of reactants and products, as well as other operating parameters such as temperature and pressure, remain constant over time 5

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7. INSTRUMENTATION 7

8. Pumps : Used to deliver reproducible quantities of solvents and reagents; the usual types are piston, peristaltic, syringe or gear centrifugal pumps. Reaction loops : Used to introduce small volumes of reagents. T- piece : Primary mixing point, where reagent streams are combined. Coil reactor : Provides residence time for the reaction. Column reactor : Packed with solid reagents, catalyst or scavengers. Back pressure regulators : Controls the pressure of the system Downstream unit : In-line analytics, work-up operations 8

9. CONTINUOUS STIRRED TANK REACTOR (CSTR) This type reactor used primarily for liquid phase reactions. It is normally operated at steady state . It is a vessel to which reactants are added and products removed while the contents within the vessel are vigorously stirred using internal agitation or by internally ( or externally) recycling the contents. 9

10. Here an agitator is introduced to disperse the reactants thoroughly into the reaction mixture immediately after they enter the reactor. 10

11. Continuous stirred-tank reactors have following characteristics: Continuous flow passes through a CSTR, both input and output streams. But not certainly at equal rates. The mass of the system inside a CSTR is not necessarily steady. The fluid is perfectly mixed inside a CSTR. Hence, its properties are consistent at any time because of adequate stirring. The flow in the system may not necessarily have a constant density. The density of the inlet flow may vary among the process to reach the exit and have a different density output stream. Provide some kind of heat transfer equipment for temperature control. 11

12. ADVANTAGES Large number of the product can be produced at low cost. Good temperature control. Reactor has a large heat capacity. Interior of the reactor is easily accessed. Good control. Easy to clean. Continuous operation DISADVANTAGES Very costly as large amounts of equipment are required. It has size limitation because of motor size, weight, and shaft length. Reactants can bypss because of improperly positioned outlet. Consumption of more power due to presence of mechanical pumps. 12

13. SYNTHETIC APPLICATIONS McQuad’s flow synthesis of Ibuprofen The three step synthesis ( Friedal - crafts acylation, 1,2- migration and ester hydrolysis) was linked into a single continuous system and provided Ibuprofen Isobutyl Benzene + Propanoic acid Ibuprofen TfOH Triflic acid Phl ( OAc ) 2 , TMOF in MeOH KOH in MeOH / H 2 O 13

14. Prevention of waste Lowe and co-workers performed the addition of secondary amines to α - unsaturated compouds whereby reaction times of 17 to 25 hr were typically required to maintain thermal control over the batch process. With the help of a continuous flow, the reactor was able to access reaction times in the range of 0.8 to 5.0 hr , without the need for additional cooling. + Solvent-free 14

15. Atom Economy The atom economy of a reaction is a measure of the percentage of the mass of reactants that are incorporated into the product and is often used as a measure of waste generation. Kappe and co-workers evaluated the use of a high temperature and pressure tubular reactor to enable access to Claisen re-arrangement products without the need for long reaction times. 2-(prop-2-en-1-yl)phenol ( E thenyloxy )benzene Toluene 2-(prop-2-en-1-yl)phenol 15

16. Bio catalysis In continuous flow reactors, small quantities of precious biocatalytic material can be used to obtain detailed information regarding reaction kinetics, substrate specificity and operational stability. Ethenyl acetate 16

17. 17 Dediazonization - Fluorination of Amines The Balz – Schiemann reaction, which involves  diazotization  of the primary  aromatic amines  followed by fluorinative dediazoniation , could be achieved in preparative scale by carrying the reaction in  PPHF , in which case the isolation of the otherwise explosive intermediary  diazonium salts  is not required. This reaction has been achieved on an industrial scale in a continuous flow reactor, using HBF 4  instead of PPHF as the HF source.

18. REFERENCES Howard JR. Fluidized bed technology: Principles and applications. London, England: Institute of Physics Publishing; 1989. Wiles C, Watts P. Continuous flow reactors: a perspective. Green Chem 2012;14(1 ):38–54 . Irfan M, Glasnov TN, Kappe CO. Heterogeneous catalytic hydrogenation reactions in continuous‐flow reactors. ChemSusChem . 2011 Mar 21;4(3):300-16. Jaibiba P, Naga Vignesh S, Hariharan S. Working principle of typical bioreactors. In: Bioreactors. Elsevier; 2020; 145–173. Howard JR. Fluidized bed technology: Principles and applications. London, England: Institute of Physics Publishing; 1989. 18

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