Coal Tar Pitch Functionalization for Pyrolysis Yield
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Solution Overview
Problem
Current pyrolysis processes for coal feed struggle with efficiently processing the pitch stream, which contains aromatic hydrocarbons that are difficult to react further due to their stability, limiting the production of desirable chemical products.
Innovation Solution
A process involving pyrolyzing a coal feed to produce a coal tar stream, separating it into a pitch stream, and then functionalizing the aromatic hydrocarbons in the pitch stream by adding a functional group, which is recycled back into the pyrolysis zone, along with gasifying a second coal feed to produce syngas for generating additional chemicals like methanol, olefins, and formic acid to enhance reactivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the pitch stream is used as-is from coal tar separation, then the process is simple, but the aromatic hydrocarbons are difficult to react further due to their stability
Solution Approach 1:
The patent applies parameter changes by introducing functional groups (such as hydroxyl, carboxyl, or alkoxy groups) to the aromatic hydrocarbons in the pitch stream through chemical reactions. This modification changes the chemical parameters of the aromatic compounds, making them more reactive and easier to process into desirable chemical products while maintaining the stability of the aromatic core structure.
2Productivity
If functional groups are added to aromatic hydrocarbons in the pitch stream, then reactivity is improved, but the process complexity increases
Solution Approach 1:
The patent employs intermediary substances or catalysts to facilitate the addition of functional groups to aromatic hydrocarbons. These intermediaries act as mediators that enable the chemical transformation without requiring direct, complex reactions between the aromatic compounds and the functionalizing agents, thereby simplifying the overall process while improving reactivity.
3Productivity
If the functionalized pitch stream is recycled to the pyrolysis zone, then product yield is improved, but the processing time increases
Solution Approach 1:
The patent implements continuity of useful action by recycling the functionalized pitch stream back to the pyrolysis zone for further processing. This creates a continuous loop where the modified pitch undergoes repeated cycles of functionalization and pyrolysis, progressively improving the yield of desirable chemical products while maintaining continuous production flow.
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 makes the pitch stream more reactive, allowing for the production of progressively lighter and more reactive products, enabling further processing and increasing the yield of valuable chemicals such as methanol, olefins, and formic acid, while also utilizing the coke stream for steel production.
Implementation Method 1
Pyrolysis of coal produces coke and coal tar. The coke-making or 'coking' process consists of heating the material in closed vessels in the absence of oxygen to very high temperatures.
Implementation Method 2
The pitch stream is reacted in a reaction zone to add at least one functional group to an aromatic ring of the aromatic hydrocarbons in the pitch stream.
Implementation Method 3
A second coal feed is gasified to produce a syngas stream comprising H2 and CO.
Data Source
AI summary
A process for pyrolyzing a coal feed is described. A coal feed is pyrolyzed into a coal tar stream and a coke stream in a pyrolysis zone. The coal tar stream is separated into at least a pitch stream comprising aromatic hydrocarbons. The pitch stream is reacted in a reaction zone to add at least one functional group to an aromatic ring of the aromatic hydrocarbons in the pitch stream. The functionalized pitch stream is recycled to the pyrolysis zone.