Propylene Oxide Production via Solvent-Free Epoxidation
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Solution Overview
Problem
Current methods for producing propylene oxide using hydrogen peroxide result in undesirable ring opening byproducts due to the use of methanol and water as solvents, leading to reduced propylene oxide yield.
Innovation Solution
A method involving the oxidation of alpha-methylbenzyl alcohol with air to form hydrogen peroxide and acetophenone, followed by reacting propylene with the resulting mixture in the presence of a titanium support on zeolite catalyst, separating propylene oxide, decomposing hydrogen peroxide, and hydrogenating acetophenone to recycle alpha-methylbenzyl alcohol, thereby minimizing byproducts and eliminating the need for additional solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If methanol and water are used as solvents in the epoxidation of propylene with hydrogen peroxide, then the reaction proceeds effectively, but ring opening byproducts are formed and propylene oxide yield is reduced
Solution Approach 1:
The patent removes methanol and water solvents from the reaction system entirely. The epoxidation reaction is conducted in a solvent-free environment using only the reactants (propylene and hydrogen peroxide) and a solid catalyst (TS-1), thereby eliminating the source of ring opening byproducts while maintaining reaction effectiveness
Solution Approach 2:
The patent changes the physical state parameters of the reaction system by eliminating liquid solvents and conducting the reaction in a gas-liquid-solid phase system. This parameter change prevents the solvent-catalyzed ring opening side reactions while preserving the main epoxidation pathway
2Productivity
If hydrogen peroxide is used to epoxidize propylene, then propylene oxide is produced, but co-products and ring opening byproducts reduce the overall yield
Solution Approach 1:
The patent converts the harmful effect of hydrogen peroxide decomposition and side reactions into a benefit by using a solid TS-1 catalyst that selectively promotes the epoxidation pathway. The catalyst structure confines the reaction, directing hydrogen peroxide toward epoxide formation rather than decomposition or ring opening, thereby turning potential waste into useful product
Solution Approach 2:
The TS-1 catalyst acts as an intermediary that mediates between hydrogen peroxide and propylene. It activates hydrogen peroxide in a controlled manner and transfers the oxidizing capability to propylene through a selective mechanism, preventing direct uncontrolled reaction and minimizing byproduct formation
3Stability of the object's composition
If water is used as a cosolvent in the epoxidation reaction, then the reaction mixture is stable, but propylene glycol byproduct is formed
Solution Approach 1:
The patent completely removes water from the reaction system. Stability of the reaction mixture is achieved through the solid catalyst structure and controlled gas-liquid contact rather than aqueous solution chemistry, eliminating water-catalyzed ring opening while maintaining operational stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process effectively reduces the formation of co-products and ring opening byproducts, enhancing the yield of propylene oxide and allowing for its production without the use of methanol, thus improving the efficiency of the propylene oxide production process.
Implementation Method 1
oxidizing alpha-methylbenzyl alcohol with air to form a first reaction mixture comprising hydrogen peroxide and acetophenone
Implementation Method 2
reacting propylene with the first reaction mixture in the presence of a catalyst to form a second reaction mixture comprising propylene oxide
Implementation Method 3
epoxidation of propylene with hydrogen peroxide in methanol solution using titanium silicate catalysts (TS1)
Implementation Method 4
heating the third reaction mixture to decompose hydrogen peroxide, whereby a fourth reaction mixture is formed
Implementation Method 5
hydrogenating the acetophenone in the fourth reaction mixture with hydrogen to form a fifth reaction mixture comprising alpha-methylbenzyl alcohol
Implementation Method 6
separating the propylene oxide from the second reaction mixture to form a third reaction mixture
Data Source
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AI summary
The present disclosure relates to a method of preparing propylene oxide comprising the steps: (a) oxidizing alpha-methylbenzyl alcohol with air to form a first reaction mixture comprising hydrogen peroxide and acetophenone; (b) reacting propylene with the first reaction mixture in the presence of a catalyst to form a second reaction mixture comprising propylene oxide; (c) separating the propylene oxide from the second reaction mixture to form a third reaction mixture; (d) heating the third reaction mixture to decompose hydrogen peroxide, whereby a fourth reaction mixture is formed; (e) hydrogenating the acetophenone in the fourth reaction mixture with hydrogen to form a fifth reaction mixture comprising alpha-methylbenzyl alcohol; and (f) separating alpha-methylbenzyl alcohol from the fifth reaction mixture and returning the methyl benzyl alcohol to step (a).