Caprolactam Production from Adipic Acid
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Solution Overview
Problem
Current processes for producing epsilon-caprolactam from adipic acid are hindered by the generation of ammonium sulfate byproducts, high costs associated with petroleum-based feedstocks, and the complexity of catalytic reactions, necessitating the development of industrially scalable and cost-effective methods using renewable feedstocks.
Innovation Solution
A chemocatalytic process converting adipic acid to caprolactam using ammonia and hydrogen in the presence of heterogeneous catalysts, such as ruthenium and rhenium on titania or zirconia supports, with tert-butanol as a solvent, to achieve high yields and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional oxidation of cyclohexane is used to produce caprolactam, then caprolactam can be produced, but large amounts of ammonium sulfate byproduct are generated
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by using adipic acid instead of cyclohexane as feedstock, and employing a completely different reaction pathway (chemocatalytic conversion with ammonia and hydrogen) to avoid ammonium sulfate byproduct formation while maintaining caprolactam production efficiency
Solution Approach 2:
The patent extracts and eliminates the problematic ammonium sulfate byproduct formation step from the conventional process by adopting an alternative reaction route that uses adipic acid as substrate, thereby removing the source of the harmful byproduct while preserving the desired product formation
2Object-generated harmful factors
If hydrogen peroxide is used in the ammoximation process to eliminate ammonium sulfate, then byproduct is eliminated, but the cost increases significantly
Solution Approach 1:
The patent replaces the expensive hydrogen peroxide reagent with a more economical chemocatalytic system using ammonia and hydrogen gas, which are cheaper and more readily available industrial chemicals, thereby reducing production costs while still eliminating ammonium sulfate byproduct formation
Solution Approach 2:
The patent changes the reagent parameters from hydrogen peroxide to ammonia-hydrogen system, fundamentally altering the chemical input parameters to achieve both byproduct elimination and cost reduction simultaneously through a different reaction mechanism
3Ease of manufacture
If photochemical process is used to convert cyclohexane to cyclohexanone oxime, then capital equipment costs are reduced, but power consumption increases significantly
Solution Approach 1:
The patent replaces the photochemical reaction mechanism with a chemocatalytic mechanism, substituting light energy input with chemical catalysis using metal catalysts, thereby eliminating the need for high-power photochemical reactors while maintaining process efficiency
4Adaptability or versatility
If adipic acid is used as renewable feedstock for caprolactam production, then reliance on petroleum is reduced, but the conversion process complexity increases
Solution Approach 1:
The patent segments the complex conversion process into distinct manageable steps: (1) chemocatalytic conversion of adipic acid to caprolactam using ammonia and hydrogen with metal catalysts, (2) isolation and purification of caprolactam from the reaction mixture, enabling industrial-scale implementation of renewable feedstock utilization
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 effectively produces caprolactam with yields exceeding 50% and high selectivity, minimizing byproduct formation and reducing reliance on costly petroleum-based feedstocks, while utilizing renewable adipic acid derived from biorenewable materials.
Implementation Method 1
chemocatalytic conversion of an adipic acid substrate to intermediates amenable to cyclization to epsilon caprolactam. The processes involve heterogeneous catalysis in the presence of hydrogen, ammonia, particular heterogeneous catalysts
Implementation Method 2
The present invention is also directed to a process for producing caprolactam from adipic acid by a) converting at least a portion of the adipic acid to at least one amide selected from the group of 6-amino-6-oxohexanoic acid and adipamide in the presence of a metal oxide comprising titania, zirconia, or a mixture thereof
Data Source
AI summary
Processes are disclosed for the conversion of adipic acid to caprolactam employing a chemocatalytic reaction in which an adipic acid substrate is reacted with ammonia and hydrogen, in the presence of particular heterogeneous catalysts and employing unique solvents. The present invention also enables the conversion of other adipic acid substrates, such as mono-esters of adipic acid, di-esters of adipic acid, mono-amides of adipic acid, di-amides of adipic acid, and salts thereof to caprolactam. Solvents useful in the process that do not react with ammonia are also disclosed. Catalyst supports are disclosed which catalyze the reaction of the substrate with ammonia in the absence of added metal. Metals on the catalyst supports comprise ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and/or platinum (Pt). Heterogeneous catalysts comprising ruthenium (Ru) and rhenium (Re) on titania and/or zirconia supports are also disclosed. Further, disclosed are products produced by such processes, as well as products producible from such products.