Light Naphtha Isomerization with Two-Temperature Reactor Segmentation
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Solution Overview
Problem
Existing isomerization processes for light naphtha face challenges such as cracking of C7 paraffins to less valuable gases, benzene saturation leading to temperature rise, and undesired conversion of naphthenes to paraffins, resulting in lower octane numbers and catalyst degradation.
Innovation Solution
A two-reactor process using high coordination sulfated mixed metal oxide catalysts at different temperatures (180-210°C and 140-180°C) separates and isomerizes C5-C7 hydrocarbons, minimizing benzene saturation and maintaining naphthene equilibria to enhance octane number and catalyst life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reactor is used for isomerization of light naphtha, then the process is simpler, but cracking of C7 paraffins to gases increases and octane number decreases
Solution Approach 1:
The isomerization process is divided into two separate reactors with different functions: first reactor for paraffin isomerization at higher temperature, second reactor for naphthene isomerization and benzene saturation at lower temperature. This segmentation prevents C7 paraffin cracking while maintaining high liquid yield and octane number.
2Quantity of substance
If benzene saturation is allowed to proceed, then aromatic content is reduced, but temperature rises and catalyst degradation occurs
Solution Approach 1:
Benzene saturation is separated into the second reactor where it occurs at lower temperature (140-180°C) after the first reactor. This prevents excessive temperature rise and catalyst degradation while still achieving the desired reduction in aromatic content in the final product.
Solution Approach 2:
Paraffin isomerization is performed first in the first reactor before benzene saturation occurs in the second reactor. This preliminary action allows the exothermic benzene saturation to occur at controlled lower temperature, preventing catalyst degradation.
3Quantity of substance
If naphthenes are converted to paraffins, then paraffin content increases, but octane number decreases
Solution Approach 1:
The process separates naphthene isomerization from paraffin isomerization by using two different reactors. In the second reactor, naphthenes are converted to higher octane naphthene isomers rather than being cracked to low octane paraffins, thus maintaining high octane number while still increasing overall paraffin content through the first reactor's action.
4Productivity
If high temperature is used for isomerization, then conversion rate increases, but catalyst life decreases
Solution Approach 1:
The process divides isomerization into two temperature zones: first reactor operates at higher temperature (180-210°C) for short duration to achieve paraffin conversion, second reactor operates at lower temperature (140-180°C) for naphthene isomerization and benzene saturation. This segmentation maintains high overall conversion rate while preserving catalyst life by limiting exposure to high temperature.
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 process produces a high octane isomerate with increased liquid yield, reduced cracking, and improved catalyst longevity by converting low octane paraffins to high octane branched paraffins and inhibiting undesirable conversions.
Implementation Method 1
A two-reactor process using high coordination sulfated mixed metal oxide catalysts at different temperatures (180-210°C and 140-180°C) separates and isomerizes C5-C7 hydrocarbons
Implementation Method 2
The fractionation column receives the light naphtha hydrocarbon feed and separates the same into an i-pentane comprising stream, a stream predominantly comprising of n-pentane, n-hexane, mono and di-branched isomers of n-hexane and some methyl cyclopentane, and stream predominantly comprising of methyl cyclopentane, cyclohexane, benzene and C7 paraffinic/naphthenic hydrocarbons
Data Source
AI summary
The present invention is related to the isomerization process in which a light naphtha stream comprising of paraffinic (mono and single branched), naphthenic and aromatic hydrocarbons in the range of C5-C7 is contacted with the solid catalyst in multiple reaction zones and in presence of hydrogen to produce high octane gasoline predominantly comprising of paraffins (single and di-branched) and naphthenes. The process scheme comprises of more than one isomerization reaction section operating at different temperatures and other operating conditions. The catalyst employed in these reaction sections is a high coordination sulfated mixed metal oxide catalyst which contains at least one noble metal and sulfated zirconia in addition to the other components. The process of the present invention also comprises more than one fractionation section and recycling of a particular stream to the reaction zone for improving the isomerization of light naphtha.