Olefin Mercaptanization for Naphtha Purification
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Solution Overview
Problem
Current processes for refining hydrocarbon streams fail to efficiently convert olefins from light naphtha streams into value-added products, leading to undesirable side reactions and fouling issues due to the presence of olefins, and the by-products from mercaptan oxidation processes, such as disulfide oils, pose environmental challenges.
Innovation Solution
A process that converts olefins in light naphtha streams to mercaptans through mercaptanization, followed by a MEROX process to produce a substantially olefin-free stream, which can then be further processed to yield value-added products like ethylene and propylene, utilizing a series of steps including mercaptanization, MEROX treatment, and wet air oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If olefins are removed from light naphtha streams using conventional methods, then product purity is improved, but valuable olefin products are lost and disposal costs increase
Solution Approach 1:
The patent converts harmful olefins that cause fouling and side reactions into valuable mercaptan products through a controlled reaction with H2S. Instead of simply removing olefins as waste, the process transforms them into sellable chemical intermediates, simultaneously achieving purification and resource recovery.
Solution Approach 2:
The patent changes the chemical state of olefins by reacting them with hydrogen sulfide under controlled conditions (temperature, pressure, catalyst) to transform them from unwanted impurities into valuable mercaptan products with different physical and chemical properties.
2Quantity of substance
If olefins are present in aromatic recovery complexes, then feedstock utilization is maintained, but alkylation reactions produce undesirable poly-aromatics
Solution Approach 1:
The patent applies preliminary mercaptanization treatment to convert olefins into mercaptans before the aromatic recovery process. This pre-treatment prevents olefins from undergoing unwanted alkylation reactions with aromatics downstream, eliminating the formation of condensed poly-aromatics while maintaining feedstock utilization.
3Productivity
If olefins are treated in high temperature equipment, then processing continues, but fouling is caused by olefin presence
Solution Approach 1:
The patent extracts and removes olefins from the light naphtha stream through mercaptanization, separating them before they can cause fouling in high-temperature equipment. The converted mercaptans are removed in the liquid phase, preventing olefin-related fouling issues in downstream processing.
4Quantity of substance
If olefins are present in adsorption separation processes, then feed processing is maintained, but competitive adsorption reduces separation efficiency
Solution Approach 1:
The patent performs preliminary mercaptanization to convert olefins into mercaptans before adsorption separation. This pre-treatment eliminates competitive adsorption between olefins and aromatics on molecular sieve surfaces, ensuring high separation efficiency while maintaining continuous feed processing.
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 converts low-value sulfur-containing light naphtha into value-added products by removing olefins and producing disulfide oils that can be used as sulfiding reagents or additives, improving product purity and reducing environmental impact.
Implementation Method 1
introducing the light naphtha feedstock and hydrogen sulfide into a mercaptanization zone containing a catalyst for reaction of the H2S with the olefins to produce a treated effluent stream that is substantially free of olefins
Implementation Method 2
passing the treated effluent stream and an alkali caustic solution to a mercaptan oxidation treatment unit to produce a spent caustic and alkali metal alkane thiolate mixture stream, and a sweet light naphtha stream
Implementation Method 3
passing the spent caustic and alkali metal alkane thiolate mixture stream, catalyst, and air into a wet air oxidation zone to product a regenerated spent caustic stream and a disulfide oils product stream
Data Source
AI summary
A light naphtha feedstock containing olefins is introduced with hydrogen sulfide into a mercaptanization zone for conversion of the olefins into a mercaptan stream that is substantially free of olefins, after which the mercaptans are sent with an alkali caustic solution into a mercaptan oxidation treatment unit (MEROX) to produce a spent caustic stream and sweet light naphtha product stream that is substantially free of olefins and of mercaptans. Disulfide oils are produced from the wet air oxidation of the spent caustic, and the disulfide oils can be further processed to provide high purity olefin building blocks.