Catalyst Recirculation in n-Butyl (Meth)Acrylate Esterification
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Solution Overview
Problem
Existing processes for preparing n-butyl (meth)acrylate face challenges in catalyst recovery, water discharge, and energy efficiency, leading to unwanted emissions and secondary component formation, with limited applicability to n-butyl acrylate production.
Innovation Solution
A continuous process involving the recycling of an acidic catalyst, using a rectification column to separate phases and incorporating external water to maintain low water content, ensuring efficient phase separation and energy efficiency, while achieving high conversion and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water of esterification is removed continuously by distillation, then conversion rate increases, but energy consumption increases and secondary components form
Solution Approach 1:
The patent utilizes phase transition by forming a heterogeneous azeotrope that separates into organic and aqueous phases upon condensation. The organic phase containing water is returned to the reactor while the aqueous phase is discharged, enabling continuous water removal through phase separation rather than continuous high-energy distillation, thus reducing energy consumption while maintaining conversion rate.
Solution Approach 2:
The patent implements continuous water removal through a cyclic process where the organic phase is continuously returned to the reactor and the aqueous phase is continuously discharged. This continuous action maintains the driving force for esterification without requiring sustained high-energy input, improving energy efficiency while preserving high conversion rates.
2Ease of manufacture
If catalyst is discharged with water, then water removal is simplified, but catalyst loss increases and emissions increase
Solution Approach 1:
The patent segments the condensed vapor into two distinct phases: an organic phase containing the catalyst and water, and an aqueous phase containing most of the water. By returning the organic phase to the reactor, the catalyst is separated from the water stream that is discharged, thereby simplifying water removal while preventing catalyst loss and emissions.
Solution Approach 2:
The patent discards the aqueous phase containing most of the water while recovering the organic phase containing the catalyst. This selective discarding and recovering approach simplifies water removal by discharging only the aqueous phase while maintaining catalyst inventory through continuous recovery and reuse in the reactor.
3Productivity
If high temperature distillation is used to remove water, then water removal efficiency increases, but secondary components form and energy consumption increases
Solution Approach 1:
The patent employs phase transition at lower temperatures by forming a heterogeneous azeotrope that condenses into separable organic and aqueous phases. This allows water removal through phase separation at temperatures below those required for conventional distillation, preventing thermal decomposition and formation of secondary components while maintaining water removal efficiency.
4Productivity
If sulfuric or sulfonic acids are used as catalyst, then esterification rate increases, but SOx emissions occur during incineration
Solution Approach 1:
The patent recycles the catalyst-containing organic phase back to the reactor instead of discharging it for incineration. This recovery approach eliminates the need to incinerate the catalyst, thereby preventing SOx emissions while maintaining the high esterification rate provided by sulfuric or sulfonic acid catalysts.
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 improved catalyst recovery, reduced emissions, and enhanced energy efficiency with minimal secondary components, resulting in higher n-butyl (meth)acrylate conversion and yield.
Implementation Method 1
The water of esterification can be removed by distillation as a constituent of an azeotrope that also typically comprises the target ester
Implementation Method 2
condensing the vapor stream in a condenser (C) to form an organic phase and an aqueous phase
Implementation Method 3
continuously separating the organic phase from the aqueous phase by means of a phase separator (D)
Data Source
AI summary
The invention relates to a process for continuous production of n-butyl (meth)acrylate by reaction of (meth)acrylic acid with n-butanol in the presence of an acidic catalyst and a polymerisation inhibitor, comprising the steps, according to a first embodiment: ⋅carrying out an esterification within a reactor (A) with a column (B) attached thereto, wherein the components (meth)acrylic acid and n-butanol are used in a molar ratio in the range from 1.0:1.0 to 1.0:2.0, preferably in the range from 1.0:1.1 to 1.0:1.5, and wherein the esterification takes place at a temperature in the range from 80 to 150° C., preferably in the range from 100 to 130° C., and at an absolute pressure in the range from 0.2 to 5.0 bar, preferably in the range from 0.4 to 1.5 bar, resulting in a reaction product (6) and a vapour stream at the head of the column (B), ⋅discharging the vapour stream at the head of the column (B), ⋅condensing the vapour stream in a condenser (C), forming an organic phase enriched with n-butyl (meth)acrylate and an aqueous phase, ⋅continuously separating the organic phase from the aqueous phase by means of a phase separator (D), ⋅feeding the resulting reaction product (6) into a rectification column (E), ⋅separating the azeotropes within the rectification column (E): a) water and n-butyl (meth)acrylate, b) n-butanol and n-butyl (meth)acrylate, c) n-butanol and water, d) n-butanol, n-butyl (meth)acrylate and water, wherein the rectification column (E) is operated at a bottom temperature in the range from 80 to 150° C. and at a head temperature in the range from 70 to 130° C. and at an absolute pressure in the range from 0.2 to 5 bar, preferably in the range from 0.4 to 1.5 bar, ⋅discharging a gas stream enriched by the azeotrope at the head of the rectification column (E), ⋅condensing the gas stream in a condenser (F) to form an organic phase enriched with n-butyl (meth)acrylate and an aqueous phase, ⋅continuously separating the organic phase from the aqueous phase by a phase separator (G), ⋅continuously discharging at least part of the organic phase from the phase separator (G), wherein this discharged part of the organic phase enriched with n-butyl (meth)acrylate represents the raw product stream (15), ⋅discharging a high-boiling bottom product (23) from the bottom of the rectification column (E), wherein the mass flow ratio between the high-boiling bottom product (23) and the (meth)acrylic acid fed to the reactor (A) as reactant is in the range from 0.5 to 5, ⋅feeding a high-boiling sub-stream (7) of the discharged high-boiling bottom product (23) into a mixer (H), wherein the mass flow ratio between the high-boiling sub-stream (7) and the high-boiling bottom product (23) is in the range from 0.01 to 0.50, preferably in the range from 0.05 to 0.08, ⋅feeding a mixture (10) resulting from the mixer (H) into a downstream extraction phase separator (I), ⋅continuously separating the mixture (10) in the extraction phase separator (I) to obtain an organic raffinate (11) and an aqueous extract (12) containing a catalyst, wherein the aqueous extract (12) is at least partially returned to the reactor (A) and/or the rectification column (E), wherein an external water (19) is fed to the mixer (H), wherein the mass flow ratio between the mass flow of the external water (19) and the high-boiling sub-stream (7) of the discharged high-boiling bottom product (23) is in the range from 0.08 to 0.50, preferably in the range from 0.10 to 0.30.