Basic Problems of Chemical Reaction Engineering andPotential of Membrane Reactors
Department of Chemical Engineering,University of Engineering & Technology Peshawar, PAKISTAN
Challenges in Chemical Reaction Engineering
More then 30 000 specialty chemicalsapproximately 300 intermediate chemicals
produced industrially from
The vast majority of these intermediates are produced from a verylimited number of approximately 20 simple base chemicals forexample, ethylene, propylene, butane, ammonia, methanol,sulfuric acid and chlorine.
To perform efficiently the large spectrum of chemical reactions ofinterest an arsenal of specific reactor types and dedicatedoperating regimes has been developed and is applied in variousindustries.
The design of efficient and reliable reaction processes is the coresubject of Chemical Reaction Engineering, a discipline which can beconsidered nowadays as rather mature.
Challenges in Chemical Reaction Engineering
The main starting point of an analysis of reacting systems is typicallyan evaluation and quantification of the rates of the reactions ofinterest.
Based on the specific physical and chemical properties of thereactants and products a wider range of temperature and pressureconditions has to be considered during the early developmentphases.
The spectrum of reactor types available and operating principles applicableis very broad.
Reactions and reactors are often classified according to the phases present.
There are reactions that can be carried out in a single phase.However, in a reaction system often more phases are presentrequiring more sophisticated configurations and operation modes
Challenges in Chemical Reaction Engineering
The energy efficiency of endothermal and exothermal reactions performedindustrially is often not satisfactory.
In reaction networks, the selectivities and yields with respect to a certaintarget product are limited
Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan
429 May 2016
Another useful classification is based on the character of theprocess and distinguishes between continuous and discontinuous(batch) operations.
To accelerate the desired reactions and/or to influence theselectivity in reaction networks with respect to the targetproducts, frequently specific catalysts are applied.
These catalysts might be present in the same phase as the reactants(homogeneous catalysis).
To fix these often expensive materials in continuously operated
reactors, catalysts are often deposited (immobilized) on the
surface of solid porous supports (heterogeneous catalysis).
Challenges in Chemical Reaction Engineering
The energy efficiency of endothermal and exothermal reactions performedindustrially is often not satisfactory.
In reaction networks, the selectivities and yields with respect to a certaintarget product are limited
Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan
529 May 2016
Despite the large efforts devoted to further develop the field ofChemical Reaction Engineering, the performance of how chemicalreactions are carried out industrially still suffers from severalsevere limitations. Very important and not sufficiently solvedproblems are:
The rates of chemical reactions leading to desired products are often too lowto establish economically attractive processes.
The conversion of many reactions of interest isthermodynamically limited, that is, the reactions proceed also inthe opposite direction and convert products back (reversiblereactions).
Challenges in Chemical Reaction Engineering
The energy efficiency of endothermal and exothermal reactions performedindustrially is often not satisfactory.
In reaction networks, the selectivities and yields with respect to a certaintarget product are limited
Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan
629 May 2016
Despite the large efforts devoted to further develop the field ofChemical Reaction Engineering, the performance of how chemicalreactions are carried out industrially still suffers from severalsevere limitations. Very important and not sufficiently solvedproblems are:
The rates of chemical reactions leading to desired products are often too lowto establish economically attractive processes.
The conversion of many reactions of interest isthermodynamically limited, that is, the reactions proceed also inthe opposite direction and convert products back (reversiblereactions).
Concepts of Membrane Reactors
In the above figure the classic tubular reactor is shown.
This reactor possesses closed walls. Thus, the reactantsintroduced together at the reactor inlet (co - feed mode).
are typically
Often tubular reactors are filled with solid catalyst particles in order toincrease the rates and selectivities.
This classic fixed - bed or packed – bed reactor ( PBR ) is intensively studiedand used widely.
Different concepts of membrane reactors
Concept I: Retainment of homogeneous catalysts
The membrane reactor concept shown in Figure exploits themembrane to retain in the reactor soluble (homogeneous) catalysts.
Thus, it allows for continuous operation without the need to separate andrecycle the typically valuable catalysts.
Successful application for various synthesis reactions are described, forexample, by (Kragl and Dreisbach,2002).
29 May 2016 Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan8
Classification of Reactions & Reactors
Reaction:-Chemical Reactions are classified as:
Syntheses Reaction
Decomposition Reaction
Single-Displacement Reaction
Double-Displacement Reaction
Combustion Reaction
Precipitation Reaction
Oxidation/Reduction Reaction
Acid-Based Reaction
Classification of Reactions
10Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
[1]
Classification of Reactions
11Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
12Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
13Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
14Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
15Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
16Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
17Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
18Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
19Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
20Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
21Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
22Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
23Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
24Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
25Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
26Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
Classification of Reactions
27Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
Classification of Reactions
28Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016
[2]
Classification of Reactions
29Dr. Saeed GUL, Department of Chemical Engineering, UET Peshawar, Pakistan29 May 2016