Precipitated Silica Morphology via Concentrated Acid pH Control
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Solution Overview
Problem
Existing processes for preparing precipitated silica using dilute acids are inefficient in terms of productivity, energy consumption, and water usage, while also limiting the achievement of desired physicochemical characteristics such as morphology, particle size, and porosity.
Innovation Solution
A process involving the reaction of a silicate with concentrated acid, specifically sulfuric acid of at least 80% concentration, to maintain a pH between 2.5 and 5.3, which allows for improved productivity and reduced energy and water consumption, while maintaining the desired properties of precipitated silica.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dilute acid is used in the precipitation reaction, then the process is easier to operate, but productivity is reduced and energy/water consumption increases
Solution Approach 1:
The patent changes the concentration parameter of the acid from dilute (conventional) to concentrated (at least 80% by mass), which fundamentally alters the reaction kinetics and productivity. This parameter change enables faster reaction rates and higher silica precipitation efficiency while maintaining operational control through pH management between 2.5 and 5.3
2Device complexity
If dilute acid is used in the precipitation reaction, then the process is simpler, but energy consumption and water usage increase
Solution Approach 1:
The patent changes the acid concentration parameter to concentrated acid (at least 80% by mass), which reduces the total volume of acid required and consequently reduces water usage in the process. The higher acidity strength allows the reaction to proceed more efficiently, reducing energy consumption for heating and processing while maintaining process control through pH management
3Productivity
If concentrated acid is used to improve productivity, then precipitation reaction efficiency increases, but control of pH becomes more difficult
Solution Approach 1:
The patent implements a feedback control mechanism by continuously monitoring and adjusting the pH of the reaction medium to maintain it between 2.5 and 5.3. This feedback approach allows the use of concentrated acid for high productivity while preventing excessive acidification that would occur without control, thus resolving the contradiction between speed and control
Solution Approach 2:
The patent applies concentrated acid (excessive concentration compared to conventional dilute acid) but controls the amount added to achieve the desired pH range. This partial application of excessive acid strength enables high reaction productivity while maintaining operational control through precise pH management
4Loss of substance
If concentrated acid is used, then water consumption is reduced, but the risk of harmful effects increases
Solution Approach 1:
The patent uses pH control as an intermediary mechanism to mediate between the use of concentrated acid (which reduces water consumption) and the prevention of harmful effects. By maintaining pH between 2.5 and 5.3, the process harnesses the efficiency of concentrated acid while preventing uncontrolled acidification and associated harmful effects on equipment and materials
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 process enhances productivity by up to 40% and reduces energy consumption and water usage by 20-60%, while maintaining the morphological, mechanical, and rheological properties of precipitated silica comparable to those produced with dilute acid methods.
Implementation Method 1
the reaction of the silicate with the acid is carried out according to the following successive steps: (i) an aqueous suspension of precipitated silica is prepared, having a pH between 2.5 and 5.3, (ii) said aqueous suspension of precipitated silica is contacted (mixed) with acid and silicate
Data Source
AI summary
The invention relates to a method for preparing precipitated silica formed by clusters of large primary silica particles having small primary silica particles on the surface thereof, wherein the acid used in at least one of the steps of said method is a concentrated acid, preferably selected from the group consisting of: sulfuric acid having a concentration of at least 80 wt %, in particular at least 90 wt %; acetic acid or formic acid having a concentration of at least 90 wt %; nitric acid having a concentration of at least 60 wt %; phosphoric acid having a concentration of at least 75 wt %; and hydrochloric acid having a concentration of at least 30 wt %.