In the petroleum refining industry, refinery gas, as a byproduct of processes such as catalytic cracking, hydrocracking, and atmospheric and vacuum distillation, is a valuable chemical raw material and energy resource. Its main components include C1-C4 hydrocarbons (methane, ethane, propane, butane), H2, H2S, CO₂, trace amounts of olefins, and saturated water vapor. However, moisture in refinery gas can cause a series of problems such as equipment corrosion, pipeline freezing, and catalyst deactivation, seriously affecting production safety and product quality. 3A molecular sieves, with their unique adsorption properties, have become the preferred material for deep drying of refinery gas, providing a reliable guarantee for the efficient utilization of refinery gas.
3A molecular sieve is artificially synthesized aluminosilicate crystals with a regular microporous channel structure, and an effective pore size of approximately 0.3 nm. This precise pore size design endows it with a unique sieving effect: water molecules, with a dynamic diameter of 0.28 nm, can easily enter the micropores and be adsorbed; while major hydrocarbons in refinery gas (methane 0.38 nm, ethane 0.40 nm, propane 0.43 nm) and hydrogen (although with a diameter of 0.24 nm, its polarity is extremely weak) cannot enter the micropores, achieving highly selective adsorption of water only, not hydrocarbons. Simultaneously, the Na⁺ and K⁺ cations in the molecular sieve framework form strong electrostatic attraction with strongly polar water molecules, further enhancing adsorption capacity and stability, ensuring deep dehydration.
Compared to 4A molecular sieve, silica gel, and activated alumina, Super Packing Mall (PM) 3A molecular sieve exhibits significant advantages in refinery gas drying: 3A molecular sieve adsorbent has high selectivity, stable chemical properties, and deep dehydration capabilities, exhibiting a strong affinity for water molecules and adsorbing only water. In addition to adsorbing water, molecular sieve 4A zeolite also adsorbs small amounts of C1-C2 hydrocarbons; silica gel and activated alumina exhibit significant hydrocarbon adsorption. Furthermore, 3A zeolite desiccant boasts high regeneration efficiency; after adsorption saturation, regeneration via hot blowing at 200-300℃ achieves an adsorption capacity recovery rate >95%, resulting in low recycling costs and lower regeneration difficulty compared to other molecular sieves.
Besides refinery gas drying, zeolite 3A molecular sieve, due to their superior performance, is widely used in deep dehydration of natural gas and coalbed methane (to prevent pipeline freezing and blockage), and drying of cracked gases (ethylene, propylene) (to meet polymerization process requirements), becoming a core material in the field of deep gas drying.
