Circulating Fluidized Bed Reactor for High Para-Xylene Production
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Solution Overview
Problem
Conventional separation methods struggle to efficiently convert linear and branched aliphatic hydrocarbons from naphtha into aromatics, leading to low para-xylene content in xylene mixtures, high energy consumption, and byproduct formation in naphtha catalytic reforming and methanol aromatization processes.
Innovation Solution
A circulating fluidized bed reaction-regeneration device with a fluidized bed reactor and riser reactor, utilizing a metal molecular sieve bifunctional catalyst, where naphtha and methanol feedstocks undergo sequential reactions to produce aromatics, with gas-solid separation and regeneration steps to enhance para-xylene yield and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional separation methods are used to separate linear and branched aliphatic hydrocarbons from naphthenes and aromatics, then the separation process becomes complex and energy-consuming, but the conversion efficiency of linear and branched aliphatic hydrocarbons into aromatics remains low
Solution Approach 1:
The invention changes the chemical parameters by introducing methanol as a reactant and using a specific catalyst system (zeolite Y with metal modifiers) to enable direct chemical conversion of linear and branched aliphatic hydrocarbons into aromatics, replacing physical separation methods with chemical transformation
Solution Approach 2:
The invention extracts and addresses the specific problem of low aromatic potential by isolating the conversion of linear and branched aliphatic hydrocarbons as a separate reaction process using methanol-to-aromatics technology, rather than relying on conventional catalytic reforming of the entire naphtha feed
2Quantity of substance
If naphtha catalytic reforming is used to produce aromatics, then the process can handle complex naphtha composition, but the para-xylene content in the xylene mixture is limited to about 24% due to thermodynamic equilibrium
Solution Approach 1:
The invention uses methanol as an intermediary substance that provides methyl groups to benzene and toluene through methylation reactions, enabling the production of xylenes with para-xylene content exceeding thermodynamic equilibrium limitations of conventional reforming
Solution Approach 2:
The invention performs preliminary methylation of benzene and toluene with methanol before xylene isomerization equilibrium can limit the para-xylene content, thereby achieving higher para-xylene yields by acting on the aromatic intermediates rather than relying on direct reforming equilibrium
3Quantity of substance
If methanol aromatization is used to produce aromatics, then methyl groups can be provided to increase toluene and xylene production, but large amounts of alkanes and hydrogen are produced as byproducts
Solution Approach 1:
The invention merges methanol-to-aromatics conversion with naphtha catalytic reforming in a coupled process, where the aromatic intermediates from naphtha reforming undergo methylation with methanol, and the byproducts (light alkanes and hydrogen) are utilized in the overall process system
Solution Approach 2:
The invention converts the harmful byproducts (light alkanes and hydrogen) of methanol aromatization into beneficial materials by using them as feedstocks for additional aromatic production or as fuels, thereby reducing waste and improving overall process efficiency
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 device efficiently converts linear and branched aliphatic hydrocarbons into aromatics, increasing para-xylene content to 75 wt% and reducing energy consumption by controlling cascade reactions and utilizing in-situ heat generation, while maintaining high aromatic yield.
Implementation Method 1
a fluidized bed reactor and a riser reactor; the fluidized bed reactor is used for introducing naphtha feedstock and methanol feedstock
Implementation Method 2
performing the gas-solid separation on the product gas flow
Implementation Method 3
utilizing a metal molecular sieve bifunctional catalyst, where naphtha and methanol feedstocks undergo sequential reactions to produce aromatics
Implementation Method 4
increasing para-xylene content to 75 wt% and reducing energy consumption by controlling cascade reactions and utilizing in-situ heat generation
Data Source
AI summary
A circulating fluidized bed reaction regeneration device and its application method are provided. The device includes a fluidized bed reactor, a fluidized bed regenerator and a riser reactor. The fluidized bed reactor is used for introducing a naphtha feedstock and a methanol feedstock, where the naphtha feedstock is brought into contact with a catalyst from the riser reactor, so as to perform a reaction to generate a BTX-containing product gas flow and a spent catalyst, and the methanol feedstock undergoes a methylation reaction with benzene and toluene in the BTX-containing product gas flow to generate p-xylene; the product gas flow is subjected to gas-solid separation, the separated product gas is conveyed to downstream sections, unconverted naphtha is returned as a feedstock to the fluidized bed reactor, part of light alkanes is returned as a feedstock to the riser reactor, and the spent catalyst is introduced into the fluidized bed regenerator.