Titanium Oxide Catalyst for High-Temperature Cr(VI) Reduction
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Solution Overview
Problem
Existing methods for reducing hexavalent chromium (Cr(VI)) are limited, particularly at high temperatures, and require UV radiation or additional activation energy, which is not feasible in all industrial applications, especially in combination with heat exchangers where Cr(VI) forms and can cause environmental and equipment degradation.
Innovation Solution
A method using a titanium oxide surface of a catalytic element, made of pure titanium or titanium alloy, where hexavalent chromium in hot gases reacts at high temperatures (above 400°C) to reduce Cr(VI) to trivalent chromium (Cr(III)) without the need for UV radiation or additional energy sources, effectively capturing Cr(VI) and preventing its further transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV radiation is used to reduce Cr(VI) at room temperature, then Cr(VI) reduction is achieved, but additional energy sources and complex equipment are required
Solution Approach 1:
The invention extracts and eliminates the UV radiation component from the Cr(VI) reduction system. By using a titanium-based catalyst that operates autonomously at high temperatures, the patent removes the need for UV lamps, power supplies, and control systems, thereby simplifying the equipment while maintaining reduction effectiveness
Solution Approach 2:
The titanium catalyst utilizes the existing thermal energy in the flue gas to drive the Cr(VI) reduction reaction. The catalyst is activated by the high temperature environment itself, eliminating the need for external energy input devices and making the system self-sufficient
2Device complexity
If Cr(VI) is not reduced in heat exchangers, then the system structure is simple, but Cr(VI) causes environmental pollution and equipment degradation
Solution Approach 1:
The invention merges the Cr(VI) reduction function with the existing heat exchanger structure by integrating the titanium catalyst directly into the heat exchanger channels or surfaces. This combination allows simultaneous heat exchange and pollution control without adding separate treatment equipment, maintaining structural simplicity while eliminating harmful Cr(VI) emissions
Solution Approach 2:
The titanium catalyst acts as an intermediary substance that facilitates the conversion of toxic Cr(VI) to harmless Cr(III) within the heat exchanger system. The catalyst provides a surface for the reduction reaction to occur, enabling pollution control as an integrated function of the heat exchange process
3Device complexity
If high temperature Cr(VI) reduction is implemented, then no UV radiation source is needed, but the catalyst must withstand extreme temperatures
Solution Approach 1:
The invention changes the operational temperature parameter from room temperature to high temperature (above 400°C). This parameter change enables the use of thermal energy already present in flue gases to activate the catalyst, eliminating the need for UV radiation sources while the titanium material's inherent high-temperature stability handles the thermal conditions
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 method significantly reduces Cr(VI) by at least 99.7% in hot gases, making it suitable for use in heat exchangers and fuel cells, extending catalyst life by allowing for surface renewal and efficient Cr(VI) reduction, even at high temperatures, thus addressing the challenges of Cr(VI) toxicity and equipment degradation.
Implementation Method 1
guiding the hot gas containing an amount of Cr(VI) over a titanium oxide surface of a catalytic element... letting Cr(VI) in the hot gas containing an amount of Cr(VI) react with the titanium oxide surface of the catalytic element, thereby reducing Cr(VI) to trivalent Chromium Cr(III)
Implementation Method 2
Cr(VI) adsorbed at the TiO2 particles in an aqueous solution and was photo-reduced to Cr(III)
Implementation Method 3
Cr(VI) adsorbed at the TiO2 particles
Data Source
Figure 1~2
Figure 3~5
AI summary
The high temperature titanium-catalyst comprises a body, the body having a hot gas inlet and a hot gas outlet. The body comprises an array of titanium containing catalytic elements, wherein the array of titanium containing catalytic elements is arranged such that hot gas containing an amount of hexavalent chromium Cr(VI) may enter the body at the hot gas inlet, may pass through the array of titanium containing catalytic elements and may leave the body at the hot gas outlet. When the titanium-catalyst is in use, Cr(VI) in the hot gas containing an amount of Cr(VI) reacts with titanium oxide in a surface layer of the titanium containing catalytic elements, whereby the Cr(VI) is reduced to trivalent chromium Cr(III) thus reducing the amount of Cr(VI) in the hot gas containing an amount of Cr(VI).