Polysiloxane Catalyst Pore Control for Polyamine Selectivity
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Solution Overview
Problem
Conventional methods for producing polyamines like diaminodiphenylmethane and polymethylene polyphenylene polyamine using polysiloxane as a catalyst suffer from deterioration of catalytic activity and selectivity decline upon repeated use, making them industrially unsatisfactory.
Innovation Solution
A process involving a rearrangement reaction of an aniline and formaldehyde condensate in the presence of organic sulfonic acid group-containing polysiloxane, followed by partial product withdrawal and reduction of by-product peak area using liquid chromatography, with polysiloxane being reused after heating, to maintain catalytic activity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polysiloxane is repeatedly used as a catalyst for polyamine production, then production continuity is improved, but catalytic activity deteriorates and selectivity declines
Solution Approach 1:
The patent applies parameter changes by controlling the pore size distribution of polysiloxane (specifically limiting pores of 2-50 nm to 20% or less of total pores) and optimizing the rearrangement reaction conditions. These parameter adjustments prevent by-product formation that would otherwise accumulate and deactivate the catalyst, thereby maintaining catalytic activity over repeated use cycles while ensuring production continuity.
2Productivity
If polysiloxane is repeatedly used as a catalyst, then operational efficiency is improved, but selectivity of the reaction deteriorates
Solution Approach 1:
The patent utilizes porous materials by carefully controlling the pore structure of polysiloxane catalyst. By limiting the proportion of small pores (2-50 nm) to 20% or less of the total pore volume, the catalyst maintains optimal mass transfer properties and active site accessibility. This porous structure control prevents by-product formation and maintains high selectivity for diaminodiphenylmethane and polymethylene polyphenylene polyamine even after multiple reuse cycles.
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 reliably prevents catalytic activity deterioration and selectivity decline, enabling the production of polyamines with high yield and excellent selectivity over a long period even when polysiloxane is repeatedly used.
Implementation Method 1
a method for rearranging N,N'-diphenylmethylenediamine, which is a condensate of formaldehyde and aniline, is known. There has been proposed, for example, a process in which N,N'-diphenylmethylenediamine is rearranged by heating in the presence of an organic sulfonic acid group-containing polysiloxane, which is a solid acid catalyst
Implementation Method 2
a reduction step of reducing a peak area of the by-product to 1.0% or less relative to a total peak area of a peak area of the by-product, a peak area of the diaminodiphenylmethane, a peak area of the polymethylene polyphenylene polyamine and a peak area of the aniline when the product is measured by liquid chromatography using a UV detector at a wavelength of 200 nm wherein the reduction is carried out by heating the product solution containing the polysiloxane remaining after the product withdrawal step
Data Source
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AI summary
Provided is a process for producing a polyamine such as diaminodiphenylmethane and polymethylene polyphenylene polyamine, capable of reliably preventing deterioration of catalytic activity and decline in selectivity, even though polysiloxane is repeatedly used. A condensate of aniline and formaldehyde is subjected to a rearrangement reaction in the presence of an organic sulfonic acid group-containing polysiloxane to form a product containing diaminodiphenylmethane, polymethylene polyphenylene polyamine and a by-product, and when the product is measured by liquid chromatography using a UV detector at a wavelength of 200 nm, a peak area of the by-product, relative to the total peak area of a peak area of the by-product, a peak area of the diaminodiphenylmethane, a peak area of the polymethylene polyphenylene polyamine and a peak area of the aniline, is reduced to 1.0% or less.