Integrated Propane-to-1,2-Propanediol Process With In-Situ H2O2
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Solution Overview
Problem
Existing processes for producing 1,2-propanediol from propane are inefficient in terms of equipment usage and raw material consumption, and there is a need for a more optimized process that achieves higher atom efficiency.
Innovation Solution
An integrated process involving dehydrogenation of propane to produce hydrogen peroxide, followed by a series of separation and reaction steps using a catalyst mixture comprising a phase transfer catalyst and heteropolytungstate, to convert propene into 1,2-propanediol, with recycling of organic phases to enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If propene oxide is isolated and purified prior to reacting with water to make 1,2-propanediol, then product purity is improved, but process complexity and equipment requirements increase
Solution Approach 1:
The patent combines the oxidation of propene to propene oxide and the subsequent hydrolysis to 1,2-propanediol into a single integrated reaction system. The reaction mixture proceeds directly from oxidation to hydrolysis without isolating propene oxide, merging two separate process steps into one continuous operation that reduces equipment requirements while maintaining product purity.
Solution Approach 2:
The process maintains continuous reaction action by immediately hydrolyzing propene oxide as it forms in the reaction mixture. The aqueous phase is continuously present during oxidation, enabling seamless transition from propene oxide formation to 1,2-propanediol production without interruption or isolation steps, thereby reducing process complexity.
2Ease of manufacture
If traditional separate processes are used for making propene from propane and 1,2-propanediol from propene, then each step can be optimized independently, but overall raw material consumption increases and atom efficiency decreases
Solution Approach 1:
The patent merges the propane dehydrogenation step with the subsequent propene oxidation and hydrolysis steps into an integrated process flow. By combining these steps and using the in-situ generated propene oxide directly, the process achieves better overall atom efficiency and reduces raw material consumption compared to traditional separate processes.
Solution Approach 2:
The process uses the hydrogen produced during propane dehydrogenation and the oxygen from air to generate hydrogen peroxide in-situ, which then serves as the oxidizing agent for converting propene to propene oxide. This self-service approach eliminates the need for external hydrogen peroxide supply and improves overall material efficiency.
3Reliability
If propene oxide is isolated before hydrolysis, then reaction control is improved, but process time and productivity are reduced
Solution Approach 1:
The process maintains continuous reaction action by immediately hydrolyzing propene oxide as it forms in the reaction mixture. The aqueous phase is continuously present during oxidation, enabling seamless transition from propene oxide formation to 1,2-propanediol production without interruption or isolation steps, thereby reducing process time and increasing productivity.
Solution Approach 2:
The aqueous phase acts as an intermediary that serves dual purposes: it provides the water necessary for hydrolysis of propene oxide and simultaneously acts as a heat sink to control the exothermic oxidation reaction. This mediator approach allows reaction control without requiring isolation of the intermediate propene oxide.
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
The process achieves 1,2-propanediol production with reduced equipment and raw material requirements, optimizing atom efficiency through the stoichiometric conversion of propane to 1,2-propanediol.
Implementation Method 1
reacting all or a part of stream S7 with stream S5 in the presence of a catalyst mixture comprising a phase transfer catalyst and a heteropolytungstate
Implementation Method 2
catalyst mixture comprising a phase transfer catalyst and a heteropolytungstate in a liquid reaction mixture comprising an aqueous phase with a maximum apparent pH of 6 and an organic phase
Implementation Method 3
liquid reaction mixture comprising an aqueous phase with a maximum apparent pH of 6 and an organic phase
Data Source
AI summary
A process for preparing 1,2-propanediol involves dehydrogenating propane to provide a product stream containing propane, propene, and hydrogen; and separating the product stream into a stream containing essentially hydrogen, a stream enriched in propane, and a stream enriched in propene. The process then involves reacting the stream containing essentially hydrogen with oxygen to provide a stream containing hydrogen peroxide; and reacting the stream enriched in propene with the stream containing hydrogen peroxide in the presence of a catalyst mixture, containing a phase transfer catalyst and a heteropolytungstate, in a reaction mixture with two liquid phases. The process further involves separating the reaction mixture of the propene oxidation into an aqueous phase and an organic phase, recycling the organic phase to the propene oxidation, and separating 1,2-propanediol from the aqueous phase.