Fluidized Bed Reactor Catalyst Distribution for Nitrile Yield
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Solution Overview
Problem
In fluidized bed reactors, unsaturated nitriles produced in the lower dense catalyst zone are decomposed when reacting with the catalyst in the upper sparse catalyst zone, leading to reduced yield.
Innovation Solution
A process dividing the reactor's internal space into upper and lower zones with specific catalyst density ratios and controlling superficial gas velocity and oxygen concentration to inhibit decomposition, using a fluidized bed reactor with a catalyst that includes molybdenum, vanadium, and antimony, and optimizing the catalyst distribution to enhance reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fluidized bed reactor operates continuously for a long period, then production capacity is maintained, but catalyst activity decreases and catalyst particle size distribution changes
Solution Approach 1:
The reactor internal space is divided into an upper space and a lower space, with the lower space containing the dense catalyst zone where the main reaction occurs and the upper space containing the sparse catalyst zone. This segmentation allows different regions to serve different functions, preventing uniform catalyst deterioration throughout the reactor and maintaining stable catalyst activity over time.
Solution Approach 2:
Different regions of the reactor are given different catalyst densities and functions. The lower space has high catalyst density for efficient reaction, while the upper space has low catalyst density to prevent over-reaction and decomposition. This local differentiation optimizes both productivity and catalyst stability.
2Productivity
If the catalyst density in the upper space is high, then reaction efficiency is improved, but unsaturated nitrile decomposition increases
Solution Approach 1:
The upper space is designed with low catalyst density (0.05 to 0.45 times the lower space density) to create a sparse catalyst zone that does not cause excessive decomposition of unsaturated nitrile, while the lower space maintains high catalyst density for efficient reaction. This local quality differentiation resolves the contradiction between reaction efficiency and product stability.
Solution Approach 2:
By segmenting the reactor into upper and lower spaces with different catalyst densities, the patent creates distinct functional zones: the lower space for efficient ammonia oxidation and the upper space for minimal decomposition, preventing uniform high catalyst density from causing overall decomposition issues.
3Productivity
If the temperature in the dense catalyst zone is optimized, then reaction yield is improved, but catalyst deterioration accelerates
Solution Approach 1:
The reactor is segmented into two spaces with different temperature characteristics. The lower dense catalyst zone operates at optimized reaction temperature for high yield, while the upper sparse catalyst zone operates at lower temperature to prevent catalyst deterioration, allowing the system to maintain both high productivity and long catalyst life.
Solution Approach 2:
Different temperature conditions are applied to different regions: high temperature in the lower space for optimal reaction yield and lower temperature in the upper space to protect catalyst from deterioration. This local quality approach allows simultaneous optimization of yield and catalyst durability.
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 stabilizes the production of unsaturated nitriles by preventing decomposition, resulting in higher yields and improved reactor efficiency.
Implementation Method 1
a vapor phase catalytic ammoxidation reaction in the presence of a metal composite oxide catalyst
Implementation Method 2
a reaction of vapor phase catalytic oxidation using a fluidized bed reactor in the presence of ammonia and a metal composite oxide catalyst
Implementation Method 3
a cyclone to separate and recover the catalyst from the reaction product gas in the internal space
Implementation Method 4
a dispersion plate to feed an oxygen-containing gas comprising oxygen to the internal space
Data Source
Figure 1
Figure 2
AI summary
A process for producing unsaturated nitrile, using a fluidized bed reactor and comprising a reaction step of subjecting hydrocarbon to a vapor phase catalytic ammoxidation reaction in the presence of a catalyst to produce the corresponding unsaturated nitrile, wherein when an internal space of the reactor is divided into two spaces of an upper space occupying a space from an upper end of an inlet of a cyclone to an upper end of the internal space and a lower space occupying a space below the upper end of the inlet of the cyclone and ranging to a dispersion plate, a ratio of an existing amount of the catalyst in the upper space to an existing amount of the catalyst in the lower space is 0.05 to 0.45 in the reaction step.