Integrated Syngas-to-Aldehyde Process Without CO2 Azeotrope Separation
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Solution Overview
Problem
Existing processes for converting syngas to lower hydrocarbons, such as C2 to C4 hydrocarbons, face challenges in achieving high productivity while minimizing CO2 selectivity, leading to increased costs and reduced efficiency due to the presence of azeotropes like ethylene/carbon dioxide and ethane/carbon dioxide, and co-feeding CO2 results in decreased productivity of desired hydrocarbons.
Innovation Solution
A two-stage process involving a first reactor with a mixed metal oxide and microporous catalyst to convert syngas into C2 to C4 hydrocarbons, followed by a second reactor for hydroformylation to produce aldehydes, where CO2 is recycled and used as an inert or in water gas shift, eliminating the need for azeotrope separation and enhancing carbon utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extractive distillation is used to break azeotropes, then separation of CO2 from olefins is improved, but process cost increases
Solution Approach 1:
The patent removes CO2 from the syngas feed stream before it enters the Fischer-Tropsch synthesis reactor. By extracting CO2 beforehand, the harmful azeotropic mixtures are prevented from forming in the first place, eliminating the need for costly extractive distillation while maintaining clean separation of desired hydrocarbon products
Solution Approach 2:
The CO2 removal step is performed as a preliminary action before the main Fischer-Tropsch synthesis reaction. This pre-treatment of the syngas feed prevents the formation of problematic azeotropes during synthesis, avoiding the need for complex downstream separation processes
2Manufacturing precision
If amine scrubbing is used to separate CO2, then azeotrope separation is improved, but process complexity increases
Solution Approach 1:
The patent extracts CO2 from the syngas stream using a physical absorption process with a selective solvent. This removes CO2 before synthesis, preventing azeotrope formation and eliminating the need for complex amine scrubbing systems or extractive distillation columns
Solution Approach 2:
The patent replaces complex mechanical separation systems (extractive distillation columns, amine scrubbing towers) with a simpler chemical absorption process using a selective solvent. This substitution reduces equipment complexity while achieving the same CO2 separation objective
3Quantity of substance
If co-feeding CO2 is used to reduce net CO2 selectivity, then CO2 balance is improved, but productivity of C2 to C4 hydrocarbons decreases
Solution Approach 1:
Instead of adding CO2 to the feed to manage CO2 balance (the conventional approach), the patent inverts the strategy by removing CO2 from the feed beforehand. This prevents CO2 from interfering with the synthesis reaction, maintaining high productivity while achieving favorable CO2 balance through the removal process itself
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 approach significantly reduces capital and operating costs by eliminating azeotrope separation and achieves high productivity of C2 to C4 hydrocarbons with efficient carbon utilization, producing aldehydes like propionaldehyde and butyraldehyde.
Implementation Method 1
converting the first feed stream into a first product stream comprising C2 to C4 hydrocarbons in the reaction zone in the presence of a first catalyst
Implementation Method 2
converting the second feed stream into a second product stream comprising propionaldehyde and/or butyraldehyde in the presence of a second catalyst in a second reactor
Data Source
AI summary
A process for preparing aldehydes from synthesis gas includes introducing a first feed stream comprising hydrogen gas and a carbon-containing gas comprising carbon monoxide into a reaction zone of a first reactor, converting the first feed stream into a first product stream comprising C2 to C4 hydrocarbons in the reaction zone in the presence of a first catalyst, wherein the first product stream further comprises carbon dioxide, removing water and C4 and higher hydrocarbons from the first product stream to form a second feed stream, and converting the second feed stream into a second product stream comprising propionaldehyde in the presence of a second catalyst in a second reactor. The propionaldehyde can further be converted to methyl methacrylate via oxidative esterification.