1. Core Uses of Alumina Desiccant (with Technical Parameters)

Alumina desiccants  are highly effective in drying and purifying gases and liquids due to their deep moisture adsorption, high mechanical strength, and excellent renewability. Their core applications span multiple industries:

1.1. Industrial Gas Drying (Core Application)**

Applicable Gases:

 Natural gas, liquefied petroleum gas (LPG), olefins (ethylene, propylene), hydrogen, oxygen, nitrogen, compressed air, carbon dioxide, etc.

Application Scenarios:

Petrochemical Industry: Drying of cracking gas and synthesis gas to prevent catalyst poisoning and equipment corrosion. Drying of natural gas in long-distance pipelines (with a dew point requirement of ≤ -60°C) to prevent freezing and hydrate formation.

Air Separation:Drying of air before oxygen/nitrogen production to maintain molecular sieve efficiency and extend equipment lifespan.

Electronics/Semiconductors: Drying of high-purity gases (such as hydrogen and nitrogen) to prevent moisture contamination that could affect chip manufacturing processes.

Technical Parameters:

Drying Depth: Dew point below -70°C.

Static Adsorption Rate: ≥ 15% (at 60% relative humidity).

Water Removal:Capable of removing both free and bound water.

1.2. Liquid Dehydration and Purification

Applicable Liquids:

Organic solvents (e.g., ethanol, acetone, toluene, xylene), lubricating oils, refrigerants, fuel oils, hydraulic oils, etc.

Application Scenarios:

Chemical Solvent Recovery: Improves the purity of solvents by removing moisture to ensure the quality of subsequent reactions or distillation.

Lubricating and Hydraulic Oils: Removes moisture to prevent emulsification, equipment wear, or corrosion (moisture content should be kept below 50 ppm).

Refrigerants: Dehydration to prevent ice formation or corrosion in refrigeration systems, such as air conditioning and cold storage.

1.3. Purification in Special Fields

Drinking Water Treatment: Defluorination and arsenic removal (defluorination capacity ≥ 3.0 mg/g at pH 6-8). It’s used in high-fluoride areas, adhering to GB 5749-2022 drinking water standards.

Waste Gas Treatment: Adsorption of acidic pollutants like hydrogen sulfide (H₂S), sulfur dioxide (SO₂), and hydrogen fluoride (HF) from industrial waste gases, especially in chemical and metallurgical industries.

Food & Pharmaceutical Industry: Desiccant use in packaging (e.g., for tablets and capsules) and moisture prevention for food products (e.g., milk powder, nuts). Meets FDA and GMP standards due to its non-toxic, odorless, and dust-free nature.

1.4. Other Applications

Catalyst Support: High specific surface area (≥ 280 m²/g) and porous structure make it ideal for supporting precious metal catalysts (e.g., platinum and palladium) in hydrogenation and oxidation reactions.

Transformer Oil Drying: Removes moisture from transformer oil to prevent insulation degradation, ensuring the safe operation of power equipment.

2. Key Precautions for Use of Alumina Desiccant (Before, During, Regeneration, and Storage)

2.1. Preparation Before Use

Avoid Pollution: Open immediately after unpacking to prevent contamination from oil, dust, or strong acids/bases. These contaminants can clog pores and damage the crystal structure, permanently reducing adsorption efficiency.

Inspect Appearance: Ensure desiccant particles are intact (no breakage or pulverization). If there is excessive powder, screen it before use to avoid system resistance or pipeline blockage.

Preprocessing: For high-purity applications (e.g., electronics and pharmaceuticals), purge the desiccant bed with dry gas (such as nitrogen) to remove any moisture adsorbed during storage and transportation.

2.2. Process Control During Use

Temperature: Maintain an optimal operating temperature of 20-80°C. Temperatures over 120°C may reduce adsorption capacity, while temperatures under 0°C may slow down the adsorption rate.

Pressure: Operates well under pressures ranging from atmospheric to 3.0 MPa. Increasing pressure enhances adsorption efficiency, but ensure it’s compatible with the equipment’s pressure resistance.

Flow Rate: Ideal gas flow rate ≤ 0.5 m/s and liquid flow rate ≤ 0.1 m/s to avoid insufficient adsorption and prevent particle wear from high flow rates.

Avoid Liquid Impact: Prevent raw gas from carrying liquid (e.g., condensed water). Install a separation tank before the drying tower to prevent expansion or pulverization of the desiccant.

Regular Monitoring: Continuously monitor the outlet moisture content via a dew point meter (for gas) or a moisture analyzer (for liquid). Replace or regenerate when the dew point exceeds -40°C or liquid moisture content exceeds 100 ppm.

2.3. Regeneration Operation Standards

Core Principle: Regenerate properly to restore the adsorption capacity without causing sintering or permanent damage.

Regeneration Medium: Dry air, nitrogen, or inert gas with a dew point ≤ -60°C.

Regeneration Temperature: 150-350°C (ideal range: 200-250°C). Temperatures below 150°C may lead to incomplete moisture desorption, while temperatures above 350°C risk sintering, collapsing the pore structure, and irreversibly reducing capacity.

Regeneration Time: Typically 2-4 hours, depending on bed height and adsorption capacity. Monitor the dew point of the regeneration gas to confirm complete regeneration (dew point ≤ -50°C).

Regeneration Process: Start with a low-temperature dry gas to discharge free water. Gradually raise the temperature (≤ 5°C/min), and after maintaining the temperature for desorption, allow natural cooling to room temperature before reuse.

2.4. Storage and Transportation

Sealed Storage: Store in a dry, ventilated, cool place, avoiding exposure to moisture, rain, and direct sunlight. Double-layer plastic bags or iron drums should be used for packaging.

Avoid Mixing: Never mix with acids, alkalis, oxidants, or oils to prevent contamination and loss of performance.

Transport Protection: Handle carefully to prevent damage to the packaging, particle breakage, or exposure to moisture.

2.5. Safety and Environmental Considerations

Safety: Non-toxic, odorless, and non-corrosive. However, due to its hard particles, direct contact with eyes or inhalation of dust should be avoided. It’s recommended to wear protective goggles and masks during handling.

Disposal: Expired alumina desiccants should be disposed of as general industrial waste or recycled through specialized facilities. They should not be discarded indiscriminately to prevent soil and water contamination.

3. Supplementary Explanation: Selection and Differentiation

3.1. Selection Criteria

 Particle Size: Commonly used sizes are 3-5 mm or 4-6 mm, but particle selection depends on the medium (gas/liquid), moisture content, dew point requirements, and operating conditions (temperature and pressure).

Adsorption Capacity: Choose based on moisture content and specific requirements (e.g., high surface area desiccants for deeper drying or high mechanical strength types for fluidized bed operations).

3.2. Comparison with Other Desiccants

Silica Gel vs. Alumina: Alumina desiccants offer better temperature resistance, mechanical strength, and renewability. While silica gel is cheaper, alumina is more effective at higher temperatures and more adaptable across a wide range of humidity levels (5% - 90% relative humidity).

Molecular Sieves vs. Alumina: Molecular sieves have superior selective adsorption for water but at a higher cost. Alumina desiccants are more affordable and better suited for broader humidity conditions but may be slightly less efficient in water adsorption under low humidity conditions.