1,2-Propanediol Preparation via Palladium Formic Acid Decomposition
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Solution Overview
Problem
The existing method for producing 1,2-propanediol results in the formation of formic acid as a byproduct, leading to corrosion issues in subsequent distillation steps for recovering valuable products like dipropylene glycol and tripropylene glycol.
Innovation Solution
Decompose formic acid by contacting the aqueous phase with a palladium catalyst after separating it from the reaction mixture, and recover 1,2-propanediol from the treated aqueous phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If formic acid is formed as a byproduct in the reaction of propene with hydrogen peroxide, then the production of 1,2-propanediol is achieved, but corrosion problems occur in subsequent distillation steps
Solution Approach 1:
The patent applies preliminary action by decomposing formic acid through catalytic hydrogenation before the distillation process. The aqueous phase containing formic acid is treated with a catalyst and hydrogen in a separate step prior to distillation, preventing the corrosion issues that would otherwise occur during the subsequent high-temperature distillation operations for recovering 1,2-propanediol and other glycol products
2Object-affected harmful factors
If the aqueous phase is separated and treated with palladium catalyst to decompose formic acid, then corrosion problems are reduced, but an additional processing step is required
Solution Approach 1:
The patent applies the extraction principle by separating the aqueous phase containing formic acid from the organic phase containing the glycol products after the epoxidation reaction. This separation allows the formic acid to be selectively treated in the aqueous phase through catalytic hydrogenation, while the organic phase can proceed directly to distillation without corrosion issues, thus removing the harmful component before further processing
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
Reduces corrosion problems in distillation steps by effectively decomposing formic acid, thereby improving the recovery process of 1,2-propanediol and other valuable products.
Implementation Method 1
contacting at least a part of the aqueous phase (P a ) separated in step b) with a palladium catalyst to provide a treated aqueous phase
Data Source
AI summary
In a method for preparing 1,2-propanediol comprising step a) of reacting propene with hydrogen peroxide in the presence of a 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; step b) of separating the reaction mixture into an aqueous phase (Pa) comprising 1,2-propanediol and formic acid and an organic phase (Po); step c) of recycling at least part of the separated organic phase (Po) to step a); step d) of contacting at least a part of the separated aqueous phase (Pa) with a palladium catalyst; and step e) of recovering 1,2-propanediol from the aqueous phase provided by step d); step d) reduces the content of formic acid.