Selective Benzene Reduction in Hydrocarbon Cuts
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Solution Overview
Problem
Current methods for reducing benzene content in hydrocarbon cuts, particularly in gasoline, are either costly, result in significant hydrocarbon loss, or fail to meet stringent regulatory standards without compromising octane number and yield.
Innovation Solution
A process involving a distillation and hydrogenation operation, with a hydrogenation reaction zone that can be either entirely external or partially incorporated into the distillation zone, allowing for selective reduction of benzene and other unsaturated compounds with minimal loss of yield and octane number, using a catalyst like nickel or platinum on a chlorinated alumina support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If distillation is used to eliminate light fraction containing benzene, then benzene content is reduced, but 15 to 20% of hydrocarbons are lost
Solution Approach 1:
The patent extracts and removes the light fraction containing benzene through distillation, separating it from the reformate. This directly addresses the harmful benzene content while the extracted fraction can be further processed or disposed of, resolving the contradiction by removing the harmful component while managing the associated hydrocarbon loss through controlled separation
Solution Approach 2:
The patent changes operating parameters such as distillation temperature, pressure, and reflux ratio to optimize the separation process. By adjusting these parameters, the process achieves effective benzene removal while minimizing unnecessary hydrocarbon losses, allowing precise control over what is removed and what is retained
2Object-affected harmful factors
If solvent extraction or adsorption is used to extract benzene, then benzene content is reduced, but the process becomes expensive and requires additional equipment
Solution Approach 1:
The patent replaces complex chemical extraction systems (solvent extraction, adsorption) with a simpler thermal separation system (distillation). This substitution achieves benzene removal through physical phase separation based on boiling point differences, eliminating the need for additional chemicals, solvents, or complex adsorption media, thereby reducing device complexity and operational costs
Solution Approach 2:
The patent utilizes phase transition (vaporization and condensation) during distillation to separate benzene from reformate. By exploiting the different volatility characteristics of benzene and other reformate components, the process achieves effective separation through controlled heating and condensing, avoiding the need for complex extraction equipment
3Object-affected harmful factors
If alkylation with ethylene is used to transform benzene, then benzene is converted, but secondary reactions require costly energy-intensive separations
Solution Approach 1:
The patent converts the harmful benzene into useful high-octane components through catalytic reforming. Instead of merely removing benzene, the process transforms it into valuable aromatics and iso-paraffins that contribute to gasoline quality, thereby converting a harmful substance into a beneficial product while avoiding energy-intensive separation steps
4Object-affected harmful factors
If benzene is hydrogenated to cyclohexane, then benzene is removed, but selective hydrogenation requires fractionation which increases complexity
Solution Approach 1:
The patent segments the reformate into different fractions through distillation before selective hydrogenation. By separating the reformate into light and heavy fractions, the process can selectively hydrogenate benzene in the light fraction without affecting other components, achieving selective removal while managing complexity through staged 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 reduces benzene content in various hydrocarbon cuts to comply with regulatory standards while maintaining a high octane number and minimizing energy consumption and investment costs, allowing for the production of a better quality paraffin isomerization charge.
Implementation Method 1
a distillation zone (2), comprising an exhaustion zone and a rectification zone
Implementation Method 2
a reaction zone hydrogenation, at least partly external to the distillation zone, comprising at least one catalytic bed
Implementation Method 3
using a catalyst like nickel or platinum on a chlorinated alumina support
Data Source
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AI summary
Process for treating charge comprising hydrocarbon containing at least 4C per molecule and at least one unsaturated benzene compound, comprises treating at least a second charge comprising unsaturated benzene compound, and partially or directly injecting the benzene compound into the hydrogenation reaction zone external to the distillation zone, where: the treatment is carried out in a distillation zone, a depletion zone and a rectification zone associated with a hydrogenation reaction zone, which is partially external to the distillation zone and comprises at least one catalyst bed. Process for treating charge comprising hydrocarbon containing at least 4C per molecule and at least one unsaturated benzene compound, comprises treating at least a second charge comprising unsaturated benzene compound, and partially or directly injecting the benzene compound into the hydrogenation reaction zone external to the distillation zone, where: the treatment is carried out in a distillation zone, a depletion zone and a rectification zone associated with a hydrogenation reaction zone, which is partially external to the distillation zone and comprises at least one catalyst bed, in which the hydrogenation is carried out by at least a part of the unsaturated compounds contained in the charge in presence of a hydrogenation catalyst and a gas stream comprising hydrogen; the charge of the reaction zone is sampled at a height of at least one level of sampling in the distillation zone; and the effluent of the reaction zone is at least partially reintroduced in the distillation zone at a height of at least a level of reintroduction to ensure the continuity of the distillation and exiting in the head of the distillation zone by laterally removing an effluent depleted in unsaturated compounds in the distillation zone or at the bottom of the distillation zone.