Mullite Bed Material for Stable Sugar Thermolysis
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Solution Overview
Problem
Existing pyrolysis processes for converting sugars into C1-C3 oxygenates, such as glycolaldehyde, face challenges in achieving high efficiency, long-term stability, and industrial scalability due to issues with bed material fluidization, yield variability, and catalytic side-reactions.
Innovation Solution
A circulating fluidized bed system using heat carrying particles with a low surface area (below 3 m2/g) and composed of at least 90% silicium, aluminium, and oxygen, which are calcined at high temperatures to form mullite, reducing acid sites and improving fluidization characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional bed materials (sand, silica, glass, alumina, steel, silicon carbide) are used in circulating fluidized bed pyrolysis, then the process can operate at high temperatures (250-900°C) for sugar conversion, but the fluidization characteristics deteriorate and yield variability increases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the particle size distribution (D10: 20-40 μm, D50: 63-125 μm, D90: 125-250 μm) and surface area (0.5-5 m²/g) of the bed material particles. These parameter optimizations resolve the contradiction by enabling stable fluidization at high operating temperatures while maintaining consistent sugar conversion rates and reducing yield variability.
Solution Approach 2:
The patent uses composite bed material comprising multiple particle size fractions with specific surface area characteristics. This composite structure resolves the contradiction by combining fine particles (for heat transfer and fluidization stability) with coarser particles (for structural integrity and reduced yield variability), enabling reliable high-temperature operation.
2Speed
If bed material with high surface area is used to increase heat transfer efficiency, then heating rate improves, but catalytic side-reactions increase and glycolaldehyde yield decreases
Solution Approach 1:
The patent resolves this contradiction by optimizing the surface area parameter to a specific range (0.5-5 m²/g). This parameter change enables sufficient heat transfer for high heating rates (>1000°C/s) while minimizing the surface area available for catalytic side-reactions, thereby maintaining high glycolaldehyde yields above 50%.
Solution Approach 2:
The patent applies local quality by ensuring the bed material has uniform surface area characteristics throughout the particle population. This uniformity ensures consistent heat transfer performance while preventing localized catalytic activity that would otherwise promote side-reactions and reduce glycolaldehyde yield.
3Ease of operation
If bed material particle size is reduced to improve fluidization, then fluidization characteristics improve, but particle entrainment and loss increase
Solution Approach 1:
The patent applies segmentation by dividing the bed material into distinct particle size fractions (D10: 20-40 μm, D50: 63-125 μm, D90: 125-250 μm) with specific distribution ratios. This segmentation resolves the contradiction by using fine particles for fluidization quality while incorporating coarser particles that are less prone to entrainment, thereby reducing overall bed material loss.
Solution Approach 2:
The patent uses a composite particle size distribution combining fine and coarse fractions. This composite structure resolves the contradiction by leveraging the fluidization benefits of fine particles while the coarser particles provide ballast that reduces entrainment and material loss during operation.
4Productivity
If high temperature thermolysis (400-600°C) is used to achieve high conversion, then sugar conversion efficiency improves, but bed material stability and long-term operation reliability deteriorate
Solution Approach 1:
The patent uses composite bed material with optimized composition and particle size distribution that maintains structural integrity at high temperatures. This composite structure resolves the contradiction by providing thermal stability and resistance to sintering or degradation, enabling long-term operation at 400-600°C while maintaining high sugar conversion efficiency.
Solution Approach 2:
The patent optimizes physical parameters of the bed material (particle size distribution, surface area, density) to enhance thermal stability. These parameter changes resolve the contradiction by enabling the bed material to withstand prolonged exposure to high temperatures without degradation, thus maintaining both conversion efficiency and operational reliability.
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 solution achieves high yields of glycolaldehyde (above 50%) with improved fluidization and long-term stability, making the process suitable for continuous industrial-scale operation.
Implementation Method 1
heat carrying particles are circulated to a heating zone to produce heated heat carrying particles, and then the heated heat carrying particles are circulated from the heating zone to a fragmentation zone to provide heat
Implementation Method 2
circulating fluidized bed system... heat carrying particles are circulated to a heating zone... and then the heated heat carrying particles are circulated from the heating zone to a fragmentation zone
Implementation Method 3
thermolytic fragmentation... selective decomposition of monosaccharides into C1-C3 oxygenates brought about by heating the sugar to intermediate temperatures (400-600°C.) under inert conditions
Implementation Method 4
thermolytic fragmentation of a sugar into a composition comprising C1-C3 oxygenates... thermal decomposition of carbonaceous materials at elevated temperatures in an inert atmosphere
Implementation Method 5
circulating fluidized bed system... Providing a circulating, fluidized stream of heat carrying particles
Data Source
AI summary
The present invention relates to a process for thermolytic fragmentation of a sugar into a composition comprising C1-C3 oxygenates. In particular, it relates to the use of heat carrying particles providing improved yields of C1-C3 oxygenates and improved fluidization characteristics making it suitable for industrial scale production of e.g. glycolaldehyde. It also regards a circulating fluidized bed system comprising the heat carrying particles.