Olefin Removal in BTX Raffinate via Liquid Hydrogenation
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Solution Overview
Problem
Conventional methods for separating normal paraffin and isoparaffin from raffinates during BTX reforming processes face efficiency issues due to olefin contamination, which deactivates adsorbents and reduces separation purity and yield.
Innovation Solution
A method involving a liquid hydrogenation process with specific conditions to remove olefin, followed by an adsorption process using zeolite adsorbents and butane purging, to selectively separate and purify normal paraffin and isoparaffin, ensuring high purity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adsorption process is used to separate normal paraffin and isoparaffin, then separation can be achieved, but olefin concentrates in adsorbent pores and deactivates adsorbent, reducing separation efficiency
Solution Approach 1:
The patent applies preliminary action by performing liquid hydrogenation before the adsorption process to remove olefins from the raffinate. This pre-treatment prevents olefin concentration in adsorbent pores during subsequent adsorption, maintaining adsorbent activity and separation efficiency throughout operation.
Solution Approach 2:
The patent converts the harmful effect of olefins (which deactivate adsorbents) into a beneficial process step. By using liquid hydrogenation with specific conditions (space velocity 2-10 hr⁻¹, hydrogen to olefin molar ratio 1.0-1.5, temperature 40-60°C), olefins are selectively hydrogenated to paraffins, transforming the problem into a solution that also improves feed quality for adsorption.
2Productivity
If conventional separation methods are used, then normal paraffin and isoparaffin can be separated, but olefin causes adsorbent deactivation and reduces yield
Solution Approach 1:
The patent removes olefins through liquid hydrogenation before adsorption, preventing the harmful effects that would reduce yield. This preliminary removal ensures high adsorbent activity and maintains high separation yield of normal and isoparaffins throughout the process.
Solution Approach 2:
The patent changes the physical-chemical parameters of the feed by performing liquid hydrogenation under specific conditions (space velocity 2-10 hr⁻¹, hydrogen to olefin molar ratio 1.0-1.5, temperature 40-60°C, pressure 15-30 kg/cm²G). This transforms the olefin-containing raffinate into an olefin-free or low-olefin stream suitable for high-efficiency adsorption.
3Manufacturing precision
If liquid hydrogenation is performed with high hydrogen to olefin ratio, then olefin removal is improved, but process complexity and cost increase
Solution Approach 1:
The patent optimizes hydrogenation parameters to achieve effective olefin removal with a hydrogen to olefin molar ratio of 1.0-1.5, which is lower than conventional ratios. Combined with controlled space velocity (2-10 hr⁻¹) and temperature (40-60°C), this achieves high olefin removal efficiency while simplifying the process and reducing hydrogen consumption.
Solution Approach 2:
The patent employs continuous liquid hydrogenation with controlled space velocity to maintain steady-state operation. This continuous process with optimized parameters achieves consistent olefin removal efficiency without requiring complex batch processing or excessive hydrogen injection systems.
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
The method effectively reduces olefin content to less than 0.1% by weight, preventing adsorbent deactivation and enhancing the purity and recovery rate of normal paraffin and isoparaffin, while simplifying the process and reducing costs.
Implementation Method 1
a liquid hydrogenation process for removing olefin by feeding raffinates in which hydrogen is dissolved into a reactor filled with a hydrogenation catalyst
Implementation Method 2
passing an effluent of the liquid hydrogenation process through an adsorption column filled with a zeolite adsorbent in a gaseous state to selectively adsorb normal paraffin
Implementation Method 3
desorbing and discharging the normal paraffin adsorbed in pores of the zeolite adsorbent by countercurrent purging with the butane
Data Source
AI summary
Provided is a method for separating normal paraffin and isoparaffin from raffinates of a benzene, toluene, and xylene (BTX) reforming process including C5 to C8 light naphtha, the method including: a liquid hydrogenation process for removing olefin by feeding raffinates in which hydrogen is dissolved into a reactor filled with a hydrogenation catalyst.