• Home
  • Blog
  • 3A Molecular Sieves for Petrochemical Cracked Gas Drying

3A Molecular Sieves for Petrochemical Cracked Gas Drying

Table of Contents

Introduction

Deep drying adsorbent
Achieve ultra-deep dehydration of cracked gas with 3A molecular sieves—remove water without ethylene/propylene loss, ensuring catalyst life and product purity.

In petrochemicals, dehydrating cracked gas—rich in unsaturated hydrocarbons such as ethylene and propylene—is critical. Even trace moisture can poison catalysts, corrode pipelines, and reduce product purity. Conventional drying agents like silica gel or activated alumina cannot achieve the required precision, but 3A molecular sieves, with their unique pore size and selective adsorption properties, deliver the optimal solution.

Unique Advantages – Precision Water Adsorption

3A molecular sieves (potassium A-type zeolite) have a pore size of ~3 Å—large enough for water molecules (~2.8 Å) to enter, but too small for ethylene (~4.2 Å) and propylene (~4.9 Å). This molecular size exclusion ensures water removal without hydrocarbon loss.

AdsorbentPore Size (Å)SuitabilityDrawbacks
3A3Adsorbs H₂O only, no ethylene/propylene lossRequires regeneration
4A4May adsorb CO₂, CH₄Reduces hydrocarbon yield
Silica gel20–100Broad adsorption rangeLow selectivity, saturates quickly
Activated alumina15–60Adsorbs larger moleculesLower efficiency

Conclusion: 3A molecular sieves are the only adsorbents that achieve deep dehydration without sacrificing ethylene/propylene.

Moisture Hazards in Ethylene & Propylene Production

  • Catalyst poisoning: Steam deactivates polymerization catalysts (e.g., Ziegler–Natta), reducing efficiency.

  • Equipment corrosion: At high temperature and pressure, water reacts with acidic gases (H₂S, CO₂), accelerating corrosion.

  • Product purity loss: Residual moisture causes defects like bubbles in downstream polyethylene/polypropylene production.

Industrial Applications & Regeneration

– Fixed-bed adsorption:

  • Cracked gas passes through a 3A bed, water is removed efficiently.

  • Achieves outlet dew point < –70 °C (moisture < 0.1 ppm).

  • Ideal for pretreatment before cryogenic separation.

– Regenerable for long-term use:

  • Restored via hot nitrogen purge at 200–300 °C.

  • Typical lifespan: 3–5 years, lowering OPEX.

Air separation gas purification

Conclusion- Why 3A Is Essential for Cracked Gas Drying

  • Selective precision: Removes water only, preserving ethylene/propylene yield.

  • Ultra-deep dehydration: Dew point < –70 °C meets polymer-grade specs.

  • Regenerable & durable: Cost-effective for continuous operations.

  • Industry benchmark: Adopted by global petrochemical leaders (e.g., BASF, Sinopec).

Comments

Newest Blog

Hot Product

Tags

Related Blogs

As a leading molecular sieve manufacturer, we share the latest industry news and insights on adsorbents like molecular sieves, sieve powder, and activated alumina.

placeholder
Scroll to Top

Get a Quote and Free Sample