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Questions and Answers
What is the typical temperature range for the reactor in the AIR PLANT?
What is the typical temperature range for the reactor in the AIR PLANT?
- 200-300 °C (correct)
- 300-400 °C
- 400-500 °C
- 100-200 °C
The process stream exiting the reactor contains 10-15 mol% of EO.
The process stream exiting the reactor contains 10-15 mol% of EO.
False (B)
What is the primary function of the purge reactor?
What is the primary function of the purge reactor?
To maintain a constant N2 concentration in the gas recycled to the reactor.
The catalyst must be replaced when the __________ temperature is reached.
The catalyst must be replaced when the __________ temperature is reached.
Match the components of the process with their functions:
Match the components of the process with their functions:
What is the per-pass ethylene conversion rate in the reactor?
What is the per-pass ethylene conversion rate in the reactor?
The AIR PLANT uses a mixture of __________ and ethylene.
The AIR PLANT uses a mixture of __________ and ethylene.
The oxygen plant has a higher ethylene loss compared to the air plant.
The oxygen plant has a higher ethylene loss compared to the air plant.
Why is it necessary to use a water-based absorber in the process?
Why is it necessary to use a water-based absorber in the process?
What is a significant difference between the air plant and the oxygen plant?
What is a significant difference between the air plant and the oxygen plant?
Which compound serves as the reaction catalyst in the aqueous phase?
Which compound serves as the reaction catalyst in the aqueous phase?
The absence of a solvent makes this chemical process highly viable on an industrial scale.
The absence of a solvent makes this chemical process highly viable on an industrial scale.
What is the first compound produced when glucose is converted in the biotechnological process discussed?
What is the first compound produced when glucose is converted in the biotechnological process discussed?
The __________ is often a phase transfer catalyst in the described reaction.
The __________ is often a phase transfer catalyst in the described reaction.
Match the following terms related to green chemistry with their descriptions:
Match the following terms related to green chemistry with their descriptions:
Why is the biotechnological method of producing adipic acid from glucose not competitive in terms of costs?
Why is the biotechnological method of producing adipic acid from glucose not competitive in terms of costs?
Green chemistry aims to eliminate the generation of hazardous substances in chemical processes.
Green chemistry aims to eliminate the generation of hazardous substances in chemical processes.
What reaction occurs after producing cis-cis-muconic acid to create adipic acid?
What reaction occurs after producing cis-cis-muconic acid to create adipic acid?
A highly likely catalyst used in this reaction is __________ anions.
A highly likely catalyst used in this reaction is __________ anions.
What is the primary function of the VaporSep unit?
What is the primary function of the VaporSep unit?
Ethylene glycol is primarily used for the production of antifreezing mixtures.
Ethylene glycol is primarily used for the production of antifreezing mixtures.
What unit is necessary to remove CO2 to prevent its adverse influence on catalyst activity?
What unit is necessary to remove CO2 to prevent its adverse influence on catalyst activity?
The product generated from the reaction with Ethylene glycol is a better __________ than water.
The product generated from the reaction with Ethylene glycol is a better __________ than water.
At what temperatures can the reaction be performed without a catalyst?
At what temperatures can the reaction be performed without a catalyst?
Match the chemical process with its purpose:
Match the chemical process with its purpose:
The VaporSep unit flares the Ethylene-enriched residue.
The VaporSep unit flares the Ethylene-enriched residue.
What is the selectivity percentage for the ring opening reaction in the production of Ethylene Glycol?
What is the selectivity percentage for the ring opening reaction in the production of Ethylene Glycol?
The mixture of water and EO is sent to the __________ for the production of Ethylene Glycol.
The mixture of water and EO is sent to the __________ for the production of Ethylene Glycol.
What is the role of acid catalyst in the Ethylene Glycol reaction?
What is the role of acid catalyst in the Ethylene Glycol reaction?
What does a high value of the selectivity constant KXYSel indicate?
What does a high value of the selectivity constant KXYSel indicate?
Anions with higher electronegativity are more favorably partitioned into the organic phase.
Anions with higher electronegativity are more favorably partitioned into the organic phase.
List one factor that affects the partitioning of anions between aqueous and organic phases.
List one factor that affects the partitioning of anions between aqueous and organic phases.
Anions that are more __________, less electronegative, weakly hydrated, and with an organic structure are more favorably partitioned into the organic phase.
Anions that are more __________, less electronegative, weakly hydrated, and with an organic structure are more favorably partitioned into the organic phase.
Match the factors affecting anion partitioning with their descriptions:
Match the factors affecting anion partitioning with their descriptions:
Which of the following anions would likely have the greatest affinity for association with Q+?
Which of the following anions would likely have the greatest affinity for association with Q+?
What is the primary effect of chlorine as a promoter in the reaction with silver catalyst?
What is the primary effect of chlorine as a promoter in the reaction with silver catalyst?
C-H cleavage has a lower activation energy than O-insertion into the C=C bond.
C-H cleavage has a lower activation energy than O-insertion into the C=C bond.
What intermediate can be produced from O-insertion into the C=C bond?
What intermediate can be produced from O-insertion into the C=C bond?
The activation energy for the C-H cleavage reaction is _____ kJ/mol.
The activation energy for the C-H cleavage reaction is _____ kJ/mol.
Match the following reactions with their respective activation energies:
Match the following reactions with their respective activation energies:
Which of the following conditions decreases epoxidation selectivity?
Which of the following conditions decreases epoxidation selectivity?
The barrier for desorption of the epoxide is significantly high.
The barrier for desorption of the epoxide is significantly high.
What is the main product when ethene undergoes complete combustion?
What is the main product when ethene undergoes complete combustion?
An increase in propene's selectivity for combustion is related to the production of an _____ intermediate.
An increase in propene's selectivity for combustion is related to the production of an _____ intermediate.
What reaction proceeds without a significant activation energy in the context of ethene?
What reaction proceeds without a significant activation energy in the context of ethene?
Study Notes
Aqueous Phase Reactions
- Aqueous phase reactants include reaction catalyst (tungstate anions), phase transfer catalyst (Aliquat 336), and oxidant (H2O2).
- Ionic form of catalyst interacts with H2O2 to create a coordination bond.
- Aliquat 336 facilitates the transport of the complex to the organic phase for adipic acid production through four oxidation steps.
- The absence of a solvent makes the process environmentally friendly, but industrial scalability is hindered by H2O2-related hazards and costs.
Adipic Acid from Biomaterials
- Adipic acid can be derived from biobased materials through fermentation pathways using specific enzymes.
- Glucose is converted into cis, cis-muconic acid, which requires hydrogenation to yield adipic acid.
- While this green technology is appealing, it is currently not cost-competitive with traditional production methods due to fermentation control and separation costs.
Green Chemistry Principles
- Green chemistry aims to innovate chemical technologies to minimize the generation of hazardous substances.
- Focuses on sustainability with cleaner, safer technologies to reduce pollution and utilize resources efficiently.
- Industrial sustainability has improved since the 1990s, driven by social pressure and legislation.
Reactor and Process Conditions
- In an air plant, purified air and ethylene are mixed, sent to the reactor at 200-300 °C and 10-30 atm.
- Per-pass ethylene conversion ranges from 20-30%, yielding high selectivity (70-80%).
- The process produces a mixture containing 1-3 mol% of ethylene oxide (EO), which is absorbed in water for purification.
- The exit gas contains ethylene, split into two streams for recycling and to maintain nitrogen concentration in the reactor.
Ethylene and Oxygen Plants
- Oxygen plants require similar reactor conditions and recovery systems but avoid purge zones, reducing ethylene loss.
- VaporSep technology removes impurities, allowing a higher ethylene concentration, thus increasing catalyst selectivity.
- CO2 adversely affects catalyst activity; a CO2 absorber unit with basic washing is necessary to mitigate this issue.
Ethylene Oxide Applications
- Ethylene oxide is flammable and typically processed further through ring-opening reactions to create various chemicals, notably ethylene glycol.
- Ethylene glycol is a key monomer for producing PET, used for plastics with excellent thermal properties.
- Synthetic methods include reactions with terephthalic acid or vanillin derived from renewable lignin.
Ethylene Glycol Production
- Ethylene glycol synthesis involves ring-opening reactions with a water excess at 60 °C and in the presence of 1% H2SO4 to prevent oligomer formation.
- Alternative synthesis occurs at 140-230 °C and 20-40 atm without a catalyst, carefully controlling pressure and residence time.
Epoxidation Process Mechanisms
- Ethene reacts with oxygen via two pathways: C-H cleavage (high activation energy) or O-insertion into the C=C bond (low activation energy).
- The presence of chlorine as a promoter decreases valence charge on oxygen, favoring ethylene epoxidation.
- Propene's reactions follow a similar pattern, with direct H abstraction yielding lower epoxidation selectivity.
Aliphatic Nucleophilic Substitution
- In aqueous-organic phasing systems, quaternary salt and excess metal salt facilitate the transfer of anions into the organic phase.
- The extraction equilibria determine the capability of anions to partition between aqueous and organic phases.
- High selectivity constant (KX→Y sel) indicates favorable reactant competition and anion association.
Partitioning Factors
- Anion partitioning between phases is influenced by charge-to-volume ratio, electronegativity, hydration energy, and structure.
- More polarizable, less electronegative, weakly hydrated anions with organic structures are preferentially partitioned into the organic phase.
- Anions with greater affinity for association with quaternary cation Q+ demonstrate higher potential for substitution in reactions.
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Description
Explore the role of various reactants in aqueous phase reactions, focusing on tungstenate anions, Aliquat 336, and H2O2. Learn about the ionic/non-ionic equilibrium and the mechanism that facilitates the transfer of complexes to the organic phase with oxidation steps. This quiz will enhance your understanding of complex chemical interactions and catalysts.
