Olefin Epoxidation via Pressurized Solvent System
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Solution Overview
Problem
Current industrial processes for producing propylene oxide and ethylene oxide are inefficient, generating significant waste, requiring large amounts of chlorine and lime, and producing environmentally harmful byproducts like carbon dioxide, while also posing safety risks due to explosive gas mixtures.
Innovation Solution
A process involving the epoxidation of olefins using a Lewis acid oxidation catalyst, an organic base, and hydrogen peroxide in an organic water-miscible solvent, with a pressurizing gas to increase the olefin's solubility and reaction rate, operating at temperatures not exceeding 60°C and pressures that enhance the concentration of dissolved olefin, thereby promoting yield and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct oxidation of propylene to propylene oxide with oxygen is used, then the process would be highly desirable and efficient, but the presence of propylene's highly reactive allylic hydrogens renders this approach difficult and leads to combustion products
Solution Approach 1:
The patent changes the oxidation parameters by using hydrogen peroxide instead of molecular oxygen, and employs a molybdenum or tungsten catalyst with specific ligands to control the reaction pathway. This parameter change allows selective epoxidation without combustion, achieving high propylene oxide yields while minimizing harmful byproducts
Solution Approach 2:
The patent employs hydrogen peroxide as a strong oxidant in place of molecular oxygen, which enables more selective and controlled oxidation of the olefin double bond. This strong oxidant approach, combined with the catalyst system, accelerates the desired epoxidation reaction while avoiding the unselective combustion that occurs with direct oxygen oxidation
2Manufacturing precision
If titanium-substituted silicalite catalysts are used for propylene epoxidation with hydrogen peroxide, then high catalytic activity and selectivity are achieved, but the catalyst is rapidly deactivated and high temperature is required for regeneration
Solution Approach 1:
The patent changes the catalyst system from titanium-substituted silicalite to molybdenum or tungsten-based catalysts with specific organic ligands. This parameter change in catalyst composition and structure provides both high selectivity and enhanced stability, eliminating the rapid deactivation problem while maintaining high propylene oxide selectivity
Solution Approach 2:
The patent employs composite catalyst systems combining molybdenum or tungsten centers with specific organic ligands (such as beta-diketonates or carboxylates). This composite material approach creates a synergistic effect that enhances both the selectivity and durability of the catalyst, allowing it to maintain activity over extended reaction periods without rapid deactivation
3Productivity
If conventional ethylene oxide processes are used, then ethylene oxide is produced, but up to 30% of ethylene undergoes combustion to form carbon dioxide and water, resulting in value destruction and environmental hazard
Solution Approach 1:
The patent changes the oxidation system by using hydrogen peroxide as the oxidant and molybdenum or tungsten catalysts with specific ligands, which fundamentally alters the reaction pathway. This parameter change achieves near-complete selectivity for ethylene oxide formation, reducing combustion losses from up to 30% to minimal levels, thereby preventing value destruction and environmental harm
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 achieves high yields of propylene oxide and ethylene oxide with reduced waste and environmental impact, avoiding the formation of explosive gas mixtures and minimizing carbon dioxide production, thus improving the economic viability and safety of olefin oxide synthesis.
Implementation Method 1
adding a pressurizing gas to increase the pressure, whereby the olefin is further dissolved in said organic solvent system
Implementation Method 2
contacting the olefin with an oxidant in the presence of a Lewis acid oxidation catalyst
Implementation Method 3
epoxidation of an olefin to the corresponding epoxide using an oxidant
Data Source
AI summary
A process for the selective oxidation of olefins to epoxides comprising the step of contacting the olefin (propylene or ethylene) with an oxidant (hydrogen peroxide) in the presence of a Lewis acid oxidation catalyst (MTO), organic base (pyridine or its N-oxide), in a solvent system comprising an organic water-miscible solvent (methanol). The system is pressurized using either the olefin itself or by adding an inert pressurizing gas (nitrogen) to increase the pressure between 230 and 700 psi at a temperature between 0.7 and 1.3 times the critical temperature of the olefin. The resulting increased solubility of the olefin in the organic solvent system increases the selectivity and yield of the desired epoxide (propylene oxide or ethylene oxide).