Hollow Cylindrical Catalysts for Oxychlorination Heat Management
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Solution Overview
Problem
In the fixed-bed oxychlorination of ethylene to 1,2-dichloroethane, existing catalysts face issues with localized hot spots, low selectivity, and reduced productivity due to fragile granules and low bulk density, leading to inefficient heat exchange and increased pressure drop.
Innovation Solution
Catalysts in the form of hollow cylindrical granules with a specific geometrical configuration and pore structure, comprising copper chloride and alkali or alkaline earth metal chlorides supported on gamma alumina, with a total pore volume of 0.4 to 0.55 ml/g, predominantly formed of mesopores with diameters from 7 to 50 nm, enhancing heat exchange and catalyst loading stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ratio of external to internal diameter (De/Di) of hollow cylindrical granules is increased to improve heat exchange efficiency, then heat exchange performance is improved, but granule fragility increases and bulk density decreases
Solution Approach 1:
The patent optimizes the De/Di ratio parameter to a specific range (1.5-2.5) to balance heat exchange efficiency and granule strength. This parameter change allows the hollow cylindrical structure to provide sufficient surface area for heat transfer while maintaining structural integrity during handling and operation.
Solution Approach 2:
The patent uses composite material structure with gamma alumina support and copper chloride catalyst phases. This composite construction provides both the mechanical strength needed for the hollow cylindrical shape and the catalytic activity required for the oxychlorination reaction, resolving the contradiction between structural integrity and functional performance.
2Temperature
If the external diameter (De) or length of cylinders is increased to maintain De/Di ratio, then heat exchange surface area is improved, but inhomogeneous loading occurs and pressure drop increases
Solution Approach 1:
The patent specifies that the length of cylinders should be less than the external diameter (De < L). This partial action approach optimizes the balance between providing sufficient heat exchange surface area and ensuring uniform catalyst loading during the loading process, avoiding excessive length that would cause inhomogeneous distribution.
Solution Approach 2:
The patent divides the catalyst bed into multiple hollow cylindrical granules with optimized dimensions. This segmentation allows for more uniform distribution of catalytic material throughout the reactor bed, improving temperature control while maintaining ease of operation during loading.
3Productivity
If total pore volume is increased to improve catalyst activity, then conversion rate is improved, but bulk density decreases and productivity per unit volume is reduced
Solution Approach 1:
The patent utilizes porous hollow cylindrical granules with controlled pore structure. The pores provide pathways for reactant diffusion and product ejection, enhancing catalytic activity and conversion rate. Simultaneously, the hollow cylindrical geometry maintains high bulk density by maximizing the use of available space within the reactor bed.
Solution Approach 2:
The patent transitions from traditional solid catalyst particles to hollow cylindrical structures, adding a dimensional change that creates internal volume for pore structure while maintaining external compactness. This allows high pore volume for improved catalysis while preserving high bulk density through the hollow cylindrical configuration.
4Productivity
If micro and mesopores are the major component to improve catalytic activity, then conversion rate is improved, but pressure drop increases due to granule breakage
Solution Approach 1:
The patent employs porous hollow cylindrical granules where micro and mesopores serve as reaction pathways for improved catalytic activity. The porous structure allows efficient reactant access to active sites while the hollow cylindrical outer structure provides mechanical strength to prevent breakage and maintain low pressure drop during operation.
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 catalysts achieve higher selectivity and conversion rates with improved specific productivity and reduced pressure drop, maintaining efficient temperature control and granule integrity during the process.
Implementation Method 1
catalysts usable in fixed-bed oxychlorination of ethylene to 1,2-dichloroethane
Implementation Method 2
more efficient heat exchange
Implementation Method 3
heat exchange and lower pressure drop through the catalytic bed
Data Source
AI summary
Catalyst for the fixed bed oxychlorination of ethylene to 1,2-dichloroethane in form of hollow cylindrical granules having total pore volume from 0.4 to 0.55 ml/g prevailingly formed of micro and mesopores having diameter between 7 and 50 nm, wherein the mesopores constitute the major component, and the macropores having diameter of more than 50 nm up to 10,000 nm being present by 15-35%.