Precious metal adsorbents (such as activated carbon, molecular sieves, or resin materials loaded with precious metals such as platinum, palladium, rhodium, etc.) require scientific storage methods to maintain their physical and chemical stability and catalytic performance due to their high value and easy deactivation characteristics. The following is a standardized storage plan:
1、 Environmental control
1. Dry and moisture-proof
Priority should be given to using sealed containers equipped with color changing silicone desiccants, with a relative humidity of less than 40%. A humid environment can cause metal particles to agglomerate or the carrier to mold, especially for adsorbents made from chloride precursors.
Taboo: Avoid direct exposure to air and strictly prohibit coexistence with volatile solvents.
2. Low temperature and light avoidance
The ideal storage temperature is 5-25 ℃, away from heat sources and areas with direct sunlight. Ultraviolet radiation accelerates the phase transition of precious metals, while high temperatures intensify the migration of active components. Short term transportation can be temporarily stored in a cool place, while long-term storage in a constant temperature cabinet is required.
3. Clean and pollution-free
Isolate dust, sulfides, and acidic and alkaline gases, and it is recommended to store them separately in a fume hood. Sulfur containing compounds can cause poisoning of precious metals and corrosion of carrier structures by acidic gases.
2、 Container selection
All containers should be cleaned and dried with anhydrous ethanol before use, and halogen containing cleaning agents are prohibited.
3、 Sealing technology
1. Gas displacement method
Inject high-purity nitrogen/argon gas (purity ≥ 99.99%) into the container, replace the air at least 3 times, and finally maintain a slightly positive pressure state. This method effectively inhibits oxidation reactions and is suitable for pyridine based coordination adsorbents.
2. Vacuum packaging
For nano powders such as platinum black that are prone to spontaneous combustion, a vacuum packaging machine is used to seal them below -80kPa to block the oxygen contact path.
3. Oil seal protection
In special occasions, high boiling point silicone oil can be used to immerse the adsorbent and form a physical barrier layer, which is suitable for moisture sensitive varieties such as ruthenium based ammonia synthesis catalysts.
4、 Identification and Management
1. Dual label system
The main label indicates the ingredients, batch number, and production date; The secondary label indicates the expiration date and storage conditions, which are respectively affixed to the front and side of the container.
2. First in, first out principle
Establish an electronic ledger to record the time of storage. Inventory exceeding 6 months must undergo retesting for specific surface area and metal dispersion.
3. Emergency response
When lumps are found, they should be lightly crushed with a mortar and violent impact is prohibited; If hardening occurs, contact the supplier for regeneration treatment.
5、 Special scenario response
-Fire prevention: Although nonflammable, the decomposition products are toxic. Dry powder fire extinguishers are prohibited, and foam is prohibited.
-Transportation protection: Install shock-absorbing fillers during long-distance transportation to prevent precious metals from falling off due to severe vibrations.
-Disposal: The ineffective adsorbent shall be entrusted to a qualified unit for recycling according to the hazardous waste code HW50, and it is strictly prohibited to dispose of it at will.
By strictly controlling the temperature and humidity of the storage environment, optimizing container sealing schemes, and improving management systems, the performance degradation of precious metal adsorbents can be maximally delayed. In practical applications, parameters need to be adjusted according to the specific product manual, and if necessary, XPS or TEM characterization should be conducted quarterly to verify the metal dispersion state.