Flame Spray Pyrolysis for Metal Silicate Calcination
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Solution Overview
Problem
Conventional processes for preparing porous crystalline metal silicates, such as zeolites, are time-consuming and generate significant amounts of waste water containing harmful substances, which is difficult to dispose of, due to the need for multiple stages including filtration and washing to remove impurities.
Innovation Solution
A process involving hydrothermal synthesis followed by calcination using flame spray pyrolysis at an adiabatic combustion temperature of 450-2200°C, which reduces the number of steps and effectively disposes of waste by converting the suspension into a pulverulent, porous crystalline metal silicate without damaging the porous structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional hydrothermal synthesis with filtration and washing is used, then metal silicates are produced, but significant amounts of waste water containing harmful substances are generated
Solution Approach 1:
The harmful washing and filtration steps are extracted and eliminated from the process. The invention directly calcines the hydrothermal synthesis mixture without intermediate washing, thereby removing the source of waste water generation while maintaining product quality
Solution Approach 2:
The hydrothermal synthesis and calcination steps are merged into a continuous process where the synthesis mixture is directly fed to the fluidized bed calcination reactor. This eliminates the need for separate washing and drying steps, reducing both waste water and process complexity
2Productivity
If multiple process stages including filtration and washing are used, then impurities are removed, but the process becomes time-consuming
Solution Approach 1:
The process skips the time-consuming washing and filtration stages by directly calcining the hydrothermal synthesis mixture. The harmful impurities are destroyed during calcination rather than requiring time-intensive separation operations
Solution Approach 2:
The invention changes the processing parameters by using direct calcination at high temperatures (450-2200°C) in a fluidized bed reactor. This parameter change allows impurities to be removed through thermal decomposition rather than mechanical separation, significantly reducing processing time while maintaining product purity
3Object-generated harmful factors
If high temperature calcination is used, then waste is effectively disposed of, but the porous structure may be damaged
Solution Approach 1:
The calcination process uses periodic fluidized bed operation where material is continuously fed, heated, and discharged. This periodic action with controlled residence time allows effective waste disposal while limiting excessive thermal exposure that could damage the porous structure
Solution Approach 2:
The invention replaces conventional fixed-bed or batch calcination with fluidized bed technology. The fluidized state provides uniform heat distribution and short residence time, effectively disposing of harmful substances while preserving the delicate porous structure through controlled thermal exposure
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 conserves the metal silicate structure and porous properties, even at high temperatures, reducing waste generation and maintaining catalytic properties, as demonstrated by the production of titanium silicalite with high selectivity and yield in oxidation reactions.
Implementation Method 1
calcination is conducted by means of flame spray pyrolysis at an adiabatic combustion temperature within a range of 450-2200° C., wherein the suspension having a solids content of ≤70% by weight which is obtained in step a) is sprayed into a flame generated by combustion of a fuel in the presence of oxygen
Implementation Method 2
calcination is conducted by means of flame spray pyrolysis at an adiabatic combustion temperature within a range of 450-2200° C.
Implementation Method 3
hydrothermal synthesis in an aqueous mixture comprising (A) at least one silicon source, (B) at least one metal source and (C) at least one mineralizer to obtain an aqueous suspension comprising a porous crystalline metal silicate as reaction product
Implementation Method 4
hydrothermal synthesis in an aqueous mixture comprising (A) at least one silicon source, (B) at least one metal source and (C) at least one mineralizer to obtain an aqueous suspension comprising a porous crystalline metal silicate as reaction product
Data Source
AI summary
The present invention relates to a process for preparing a pulverulent, porous crystalline metal silicate, comprising the following steps:a) hydrothermal synthesis in an aqueous mixture comprising (A) at least one silicon source, (B) at least one metal source and (C) at least one mineralizer to obtain an aqueous suspension comprising a porous crystalline metal silicate as reaction product; andb) calcination of the reaction product, characterized in that the calcination is conducted by means of flame spray pyrolysis at an adiabatic combustion temperature within a range of 450-2200° C., wherein the suspension having a solids content of 70% by weight which is obtained in step a) is sprayed into a flame generated by combustion of a fuel in the presence of oxygen to form a pulverulent, porous crystalline metal silicate.