Reverse Isomerization in Diesel Hydrocracking for n-Paraffin Yield
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Solution Overview
Problem
Current hydrocracking processes struggle to effectively convert diesel into value-added products such as ethylene, propylene, butylene, and aromatics, leading to a surplus of diesel and limited production of these valuable chemicals.
Innovation Solution
A process that includes hydrodesulfurization, hydrodenitrogenation, hydrocracking, separation of hydrocrackate fractions, and reverse isomerization of iso-paraffins to n-paraffins, utilizing zeolite and isomerization catalysts to enhance the production of n-paraffins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydrocracking processes are used to process diesel feedstock, then the diesel is converted into smaller hydrocarbon molecules, but the process leads to a surplus of diesel and limited production of value-added products such as ethylene, propylene, butylene, and aromatics
Solution Approach 1:
The process segments the hydrocrackate fraction into different streams based on composition (n-paraffins stream and iso-paraffins/naphthenes stream), allowing targeted processing of each stream to maximize value-added product production while minimizing diesel surplus
Solution Approach 2:
The process applies reverse isomerization to convert iso-paraffins back to n-paraffins, which is the opposite of the conventional isomerization process. This inversion allows the n-paraffins stream to be enriched further and directed toward steam cracking for ethylene and propylene production, thereby increasing value-added products and reducing diesel surplus
2Reliability
If hydrocracking is performed to improve the quality of hydrocarbon feedstock by increasing hydrogen-to-carbon ratio and removing impurities, then the quality of the feedstock is improved, but the process does not effectively convert diesel into high-value chemical products
Solution Approach 1:
The process applies different quality enhancement strategies to different streams: the n-paraffins stream is directed to steam cracking for high-value olefin production, while the iso-paraffins/naphthenes stream undergoes reverse isomerization to produce high-quality n-paraffins for gasoline blending. This localized quality optimization maximizes the value-added output from each stream
Solution Approach 2:
The process introduces separation and reverse isomerization as intermediary steps between hydrocracking and final product formation. These intermediaries enable the hydrocrackate fraction to be transformed into higher-value products by converting iso-paraffins to n-paraffins and directing appropriate streams to steam cracking, thereby improving conversion efficiency to value-added products
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 significantly increases the production of n-paraffins, allowing for the conversion of diesel into gasoline blending components and high-quality gasoline products, improving the economic value and quality of the hydrocarbon output.
Implementation Method 1
hydrocracking the hydrodesulfurized and hydrodenitrogenized diesel feedstock over a metal-containing diesel hydrocracking catalyst comprising at least one zeolite to produce a hydrocrackate fraction
Implementation Method 2
reverse isomerizing at least a portion of the second stream over an isomerization catalyst to convert at least a portion of the iso-paraffins to n-paraffins
Data Source
AI summary
In accordance with one or more embodiments of the present disclosure, a process for treating a diesel feedstock to convert diesel to component-paraffins includes hydrodesulfurizing and hydrodenitrogenizing the diesel feedstock to reduce a sulfur content of the diesel feedstock and a nitrogen content of the diesel feedstock; hydrocracking the hydrodesulfurized and hydrodenitrogenized diesel feedstock over a metal-containing diesel hydrocracking catalyst comprising at least one zeolite to produce a hydrocrackate fraction; separating the hydrocrackate fraction into a first stream enriched in n-paraffins and a second stream enriched in iso-paraffins and naphthenes; and reverse isomerizing at least a portion of the second stream over an isomerization catalyst to convert at least a portion of the iso-paraffins to n-paraffins, producing a reverse isomerate fraction.