Copper chromite, the chemical formula is CuCr2O4, CAS 12053-18-8. It is a dark green powder with a polyhedral crystal structure. According to different preparation methods and surface modifications, it can also exhibit different particle sizes and shapes, such as spherical, hexagonal columnar or rod-shaped, etc. It is an excellent electrical and thermal conductor. Because it contains copper, it is able to efficiently conduct electricity and heat. In fact, it has important applications in electronics and refrigeration equipment. Solubility is very low in water and most organic solvents. This solubility limitation gives product excellent stability and reusability in catalyst applications. It is an antiferromagnetic material. When placed in an external magnetic field, its magnetic moments align in the opposite direction to the external magnetic field. This magnetism makes product have special effects in the application of catalysts. It is an inorganic metal compound. This compound is widely used in the chemical industry as a catalyst. As a catalyst, it has been widely used, and it has also shown its extremely high application value in the fields of electronics, hard alloys, refrigeration equipment, fuel cells, optical glass and pigments. These uses not only reflect the excellent physical properties of product in many aspects, but also illustrate its wide application prospects.
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Copper chromite (chemical formula CuCr2O4 or Cu2Cr2O5), as a spinel type metal oxide, plays an irreplaceable role in the aerospace field due to its unique crystal structure (copper ions occupy tetrahedral voids, chromium ions are distributed in octahedral voids) and excellent thermal stability, chemical stability, and catalytic activity. Its application runs through multiple core links such as rocket engines, missile propulsion systems, spacecraft thermal protection, energy storage and conversion, and has become a key material for promoting breakthroughs in aerospace technology.
1. Core functions and mechanisms of action
It is one of the most important combustion rate catalysts in composite solid propellants. Its metal particles have a high specific surface area and surface energy, which can significantly improve the combustion rate of propellants, while reducing the pressure index (the sensitivity of combustion rate to pressure changes), allowing the engine to maintain stable combustion over a wide pressure range. Research has shown that particle size has a significant impact on the performance of propellants:
Reducing particle size can lower the low-temperature decomposition activation energy, increase the high-temperature decomposition reaction rate, thereby improving the high-pressure combustion rate and reducing the pressure index. For example, when the particle size of oxocopper decreases from the micrometer level to the nanometer level, the burning rate of the propellant can be increased by 15% -20%, and the pressure index in the high-pressure section can be reduced by 0.2-0.3.
2. Formula optimization and synergistic effects
To further enhance performance, it is often used in combination with other combustion rate catalysts such as iron oxides and carbon nanotubes. For example, in HTPB (hydroxyl terminated polybutadiene) composite propellants, mixing oxocopper with ferrocene in a ratio of 3:1 can increase the burning rate by 25% while maintaining a pressure index below 0.5. In addition, its particle size distribution needs to be strictly controlled: too small a particle size can easily lead to agglomeration and affect dispersibility; If the particle size is too large, the catalytic efficiency will decrease. Oxocopper powder with uniform particle size can be prepared by spray drying, ball milling and other processes to ensure its uniform distribution in the propellant.
3. Typical application cases
Rocket engine: In the solid boosters of the Long March series rockets, it serves as the main combustion rate catalyst, enabling the propellant combustion rate to reach 8-12 mm/s (atmospheric pressure), meeting the high thrust requirements during rocket takeoff.
Missile propulsion system: In the third stage engine of a certain type of ballistic missile, combined with sodium borohydride composite catalyst, the propellant can maintain a burning rate of 6-8mm/s in a vacuum environment, ensuring the missile accurately hits the target.
1. High temperature stability and antioxidant activity
When spacecraft re-enter the atmosphere, the surface temperature can exceed 2000 ℃, and traditional materials are prone to failure due to oxidation. It can maintain structural stability even at high temperatures (>1500 ℃), and the dense chromium oxide (Cr ₂ O3) layer formed on its surface can effectively prevent oxygen permeation and extend the service life of the material. For example, in the thermal protection system of the return capsule, the coating can extend the temperature resistance time of the material from 120 seconds to 180 seconds, providing a guarantee for the safe landing of the spacecraft.
2. Thermal shock resistance and anti peeling performance
When spacecraft rapidly pass through the atmosphere, the surface temperature changes sharply (Δ T>1000 ℃/s), which can easily cause coating peeling. By optimizing the crystal structure (such as reducing grain size and increasing grain boundary density), the thermal shock performance can be significantly improved. Experiments have shown that the specially treated copper chromite coating maintains over 95% adhesion after 20 thermal cycles (2000 ℃ → room temperature), which is much better than traditional alumina coatings (adhesion drops to 70%).
3. Typical application scenarios
Thermal protection tile for return capsule: In the return capsule of Shenzhou series spacecraft, oxocopper coating is applied to key parts (such as the bottom and side walls), combined with silicon carbide fiber-reinforced ceramic matrix composite material (C/SiC) to form a gradient thermal protection structure, which enables the return capsule to withstand a peak heat flux density of 50MW/m ².
Hypersonic aircraft nose cone: At the nose cone of a certain type of hypersonic aircraft (speed>5 Mach), a tungsten based alloy composite coating can withstand high temperatures of 2200 ℃ while maintaining surface roughness Ra<0.8 μ m, reducing aerodynamic heating losses.
Spacecraft Energy System: The 'Core Hub' for Energy Storage and Conversion
1. Fuel cell electrode materials
In solid oxide fuel cells (SOFC), it can be used as a cathode material, and its spinel structure provides abundant oxygen vacancies, promoting the kinetics of oxygen reduction reaction (ORR). Research has shown that the polarization resistance of oxocopper based cathodes at 800 ℃ is only 0.1 Ω· cm ², which is 67% lower than traditional cobalt based cathodes (0.3 Ω· cm ²), significantly improving the battery output power density (from 0.5W/cm ² to 0.8W/cm ²).
2. Hydrogen energy storage and conversion
It has multiple applications in the field of hydrogen energy:
Photocatalytic hydrogen production: Through the photocatalytic water splitting reaction (2H ₂ O → 2H ₂+O ₂), the catalyst can achieve a solar hydrogen energy conversion efficiency of 4.2% under ultraviolet light irradiation, which is 133% higher than the traditional TiO ₂ catalyst (1.8%).
Alcohol reforming for hydrogen production: In the methanol steam reforming reaction (CH ∝ OH+H ₂ O → 3H ₂+CO ₂), oxocopper supported catalysts (such as CuCr ₂ O ₄/Al ₂ O ∝) can achieve a methanol conversion rate of 98% and a hydrogen selectivity of over 95%, providing a stable hydrogen source for spacecraft fuel cells.
3. Typical application cases
Lunar Base Energy System: In NASA's proposed lunar base plan, a oxocopper based photocatalytic device is used to produce hydrogen from lunar surface sunlight, combined with fuel cells to achieve 24-hour uninterrupted power supply. A single system can produce up to 10kg of hydrogen per day, meeting the daily needs of three astronauts.
Mars rover power supply: On the "Perseverance" Mars rover, oxocopper catalyst was applied to the auxiliary energy system of the radioactive isotope thermoelectric generator (RTG), providing backup power for the rover through methanol reforming to produce hydrogen, extending the mission life to 14 years.
1. Exhaust gas purification catalyst
The CO ₂, trace volatile organic compounds (VOCs) produced by astronauts' respiration, and NOx emitted by equipment in the sealed cabin of spacecraft need to be purified in real time. Catalysts can efficiently catalyze the oxidation of these pollutants at low temperatures (50-100 ℃):
CO oxidation: Under the action of CuCr ₂ O ₄/CeO ₂ composite catalyst, CO can be completely converted to CO ₂ at 80 ℃, with a reaction rate of 0.5mol/(g · h).
VOCs removal: For typical VOCs such as formaldehyde and benzene, the mineralization rate of oxocopper catalyst exceeds 99%, avoiding secondary pollution.
2. Water treatment materials
In the spacecraft water cycle system, it can be used as an adsorbent to remove heavy metal ions (such as Hg ² ⁺, Pb ² ⁺) and organic pollutants. The Cr OH groups with positive charges on its surface can capture heavy metal ions through electrostatic adsorption and complexation, with an adsorption capacity of 120mg/g (Hg ² ⁺), which is 140% higher than activated carbon (50mg/g).
3. Typical application scenarios
International Space Station Life Support System: In the oxygen regeneration system of the International Space Station, the catalyst bed can operate continuously for more than 5000 hours, reducing the concentration of CO ₂ from 10000ppm to below 100ppm while recovering 95% of oxygen.
Lunar Base Water Treatment Unit: In NASA's lunar base program, copper chromite based adsorption columns are used to treat astronaut urine and condensate, and the effluent quality meets NASA standards (total organic carbon<0.1mg/L, no heavy metals detected).
Future outlook: Breakthrough applications in emerging fields
1. Nano oxocopper and quantum technology
By controlling the synthesis conditions (such as solvothermal method, template method), oxocopper quantum dots with particle size<10nm can be prepared. Its quantum confinement effect can significantly enhance catalytic activity and optical performance:
Quantum computing: Quantum dots can serve as candidate materials for quantum bits, with spin lifetimes in the millisecond range, providing possibilities for building solid-state quantum computers.
Photocatalytic enhancement: The absorption coefficient of nano oxocopper in the visible light region is 5 times higher than that of bulk materials, and the photocatalytic hydrogen production efficiency can reach 8%, approaching the commercial threshold (10%).
3. Biocompatibility and Aerospace Medicine
Research has shown that surface modified oxocopper nanoparticles (such as polyethylene glycol coated) have good biocompatibility and can be used as drug carriers or biosensors:
Astronaut health monitoring: Oxocopper based sensors can detect metabolites such as glucose and lactate in astronaut body fluids in real time, with a sensitivity of pM level.
Radiation protection: Oxocopper nanoparticles can absorb high-energy particles in cosmic rays, reducing damage to astronaut DNA and increasing protection efficiency by 30% compared to traditional lead shielding.
2. 3D printing and customized manufacturing
By combining 3D printing technology such as selective laser sintering (SLS), complex oxocopper based structural components (such as combustion chambers and thermal protection tiles) can be directly prepared, achieving "design manufacturing integration". For example, oxocopper/polyimide composite materials printed by SLS have a density 40% lower than traditional castings while maintaining 90% mechanical properties.
It is an important catalyst which is widely used in the chemical industry.
1. Chemical co-precipitation method:
Chemical co-precipitation is a commonly used method for preparing product. This method requires co-precipitation of Cu(NO3)2·6H2O and Cr(NO3)3·9H2O under the combined action of hydrochloric acid and ammonia water, and then roasting the product at about 500°C to obtain pure copper chromite. The synthesis method has high accuracy and is easy to control the reaction conditions, so it is relatively common in practical applications.
2. Sol-gel method:
The sol-gel method is a method for synthesizing product by solution reaction. This method needs to add CuSO4 and NH4CrO4 to deionized water respectively, and then use NH4OH or NaOH to adjust the pH to make it produce a colloidal solution. The colloidal solution will be evaporated to dryness to form a gel, and then processed at a calcination temperature of about 600°C to finally obtain pure product. Compared with other synthetic methods, this method has the advantages of precise control of particle size, crystal structure, etc., so it has been widely used in practical applications.
In a word, it can be synthesized by various methods such as chemical coprecipitation method, sol-gel method, gas phase reaction method, ultrasonic-assisted synthesis method and template method. Different synthetic methods have their own characteristics and advantages, so an appropriate synthetic method can be selected according to specific needs.
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Chemical Formula |
CrCuO3 |
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Exact Mass |
163 |
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Molecular Weight |
164 |
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m/z |
163 (100.0%), 165 (44.6%), 164 (11.3%), 161 (5.2%), 166 (5.1%), 165 (2.8%), 163 (2.3%), 167 (1.3%) |
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Elemental Analysis |
Cr, 31.79; Cu, 38.86; O, 29.35 |
It is a double metal oxide, and its molecular structure characteristics are of great significance for its catalytic performance and application.
Oxocopper belongs to double metal oxide, its molecular structure is complex, and there are many structures. The most common one is the CuCr2O4 crystal structure, its lattice parameters are a=8.105Å, c=8.924Å, it belongs to the cubic crystal system, and the space group is Fd-3m. The CuCr2O4 crystal structure is composed of Cu2+ and Cr3+ ions alternately arranged, each Cu2+ ion coordinates with six Cr3+ ions, and each Cr3+ ion coordinates with four Cu2+ ions and two O2- ions.
In the CuCr2O4 crystal structure, the average bond length of Cu2+ ions is 0.2077nm, the average bond length of Cr3+ ions is 0.2130nm, and the average bond length of O2- ions is 0.1379nm. Due to the difference in ionic radius in the CuCr2O4 crystal structure, there are more coordination geometric isomers, such as trigonal phase, tetragonal phase, octahedral phase and dodecahedral phase. These different coordination geometric isomers may affect the properties and applications of product.
The molecular structure of it is closely related to its physical properties. It is a black powder with high thermal stability and chemical resistance. Due to its special crystal structure, it has good electrical conductivity and magnetism, and has been widely used in some electronic components and magnetic materials. In addition, it has certain thermal sensitivity, and its thermal expansion coefficient can be adjusted by changing its crystal structure.
It has certain adsorption properties due to its complex molecular structure. Studies have shown that it has good catalytic activity and selectivity, and can be widely used as an important catalyst in various chemical reactions. It is often used in organic synthesis reactions, such as oxidation, hydroxylation, hydrogenation and other reactions. Its catalytic effect is mainly realized by the active centers formed by Cu2+ and Cr3+ ions on the surface oxygen vacancies. In addition, it also has certain adsorption properties, which can adsorb some small molecular substances, such as gas and water.
In conclusion, as a double metal oxide, copper chromite's molecular structure is of great significance for its catalytic performance and application. The crystal structure of cproduct is complex, there are multiple coordination geometric isomers, its physical properties are good, it has high thermal stability and chemical resistance, and its catalytic activity and selectivity in chemical reactions are mainly through the surface Active centers formed by Cu2+ and Cr3+ ions on oxygen vacancies are realized.
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