Tetralobe Catalyst Body for SO2 Oxidation

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Solution Overview

Problem

Current catalysts for the oxidation of SO2 to SO3 have limitations in achieving a high volume-based geometric surface area with low pressure drop and maintaining high lateral compressive strength in both moist and calcined states.

Innovation Solution

The development of tetralobe-shaped catalyst bodies with four circular through-passages, where the midpoints of the passages form a square, and the spacings between adjacent passages are between 0.8 to 1.2 times the thickness of the outer wall, enhancing both extrusion and calcined state mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If traditional catalyst body shapes are used, then manufacturing is simpler, but geometric surface area per unit volume is lower and pressure drop is higher

Engineering Contradiction:

Improvegeometric surface areaVSAvoidbody shape complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The catalyst body is divided into multiple lobes (typically 3-7 lobes) with through-passages running through them, creating a segmented structure that increases geometric surface area while maintaining manufacturability through standard extrusion processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from simple cylindrical or monolithic shapes to three-dimensional lobe structures with through-passages, adding dimensional complexity that increases surface area-to-volume ratio while managing pressure drop characteristics

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Area of stationary object

If complex lobe structures with through-passages are created, then geometric surface area increases, but mechanical stability during extrusion and calcination deteriorates

Engineering Contradiction:

Improvegeometric surface areaVSAvoidlateral compressive strength

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

The invention optimizes geometric parameters including the number of lobes (3-7), the ratio of lobe radius to body radius (0.2-0.4), and wall thickness ratios to balance surface area maximization with mechanical strength requirements during extrusion and calcination processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The catalyst body uses composite material structures combining support materials with active components distributed throughout the lobe structure, enhancing mechanical properties while maintaining the desired geometric surface area

Inventive Principle:

Principle #40Composite materials

3Area of stationary object

If wall thickness is reduced to increase surface area, then geometric surface area increases, but mechanical strength and stability deteriorate

Engineering Contradiction:

Improvegeometric surface areaVSAvoidmechanical stability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The invention establishes optimal parameter ranges including wall thickness ratios (0.15-0.35 of outer radius) and spacing between through-passages (0.5-1.5 times the wall thickness) that simultaneously achieve high surface area and adequate mechanical reliability

Inventive Principle:

Principle #35Parameter changes

4Area of stationary object

If more through-passages are added to increase surface area, then geometric surface area increases, but pressure drop increases

Engineering Contradiction:

Improvegeometric surface areaVSAvoidpressure drop

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The through-passages segment the catalyst body into multiple flow paths, distributing gas flow to reduce pressure drop while the lobe structures between passages provide additional geometric surface area for catalytic activity

Inventive Principle:

Principle #1Segmentation

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 tetralobe-shaped catalyst bodies exhibit significantly higher lateral compressive strength and a larger geometric surface area with a lower pressure drop, particularly in the freshly extruded and calcined states, compared to traditional designs.

Implementation Method 1

The shaped bodies have a 27% higher specific surface and only a 15% higher pressure drop compared to shaped bodies having a star extrudate shape

Methodology Applied

Scientific EffectPressure drop: Pressure Drop

Implementation Method 2

The shaped catalyst bodies can be produced by extrusion of a catalyst precursor material which already comprises the active material

Methodology Applied

Scientific EffectExtrusion: Extrusion

Implementation Method 3

The invention also relates to a process for the oxidation of SO2 to SO3 using the shaped catalyst bodies

Methodology Applied

Scientific EffectCalcination: Heat Treatment

Data Source

PatentUS11642666B2Shaped catalyst body in the form of tetralobes of uniform wall thickness

Publication Date: 2023.05.09 BASF SE

AI summary

The invention relates to a shaped catalyst body in the form of a tetralobe having four circular through-passages, with the midpoints of the through-passages forming a square and the spacings between in each case two adjacent through-passages being from 0.8 to 1.2 times the thickness of the outer walls of the through-passages. The shaped catalyst body is used for the oxidation of S02 to S03.