How Glycerine Is Recovered as a Co-Product of Oleochemical Splitting

The Splitting Process

Oleochemical splitting—also called fat splitting or hydrolysis—is the industrial process that breaks triglycerides (fats and oils) into fatty acids and glycerine. The reaction uses high-pressure steam at temperatures around 250°C and pressures of about 50 bar, without catalysts. Water molecules attack the ester bonds, releasing free fatty acids and a dilute glycerine stream.

Glycerine Recovery Steps

Once splitting is complete, the mixture separates into two phases: a fatty acid layer (top) and a sweetwater layer (bottom) containing roughly 10–20% crude glycerine, along with water, residual fats, and impurities.

1. Sweetwater Concentration The sweetwater is first evaporated to raise glycerine concentration to about 80–88%. This step removes most of the water, reducing volume for downstream processing.

2. Purification Concentrated crude glycerine undergoes purification to remove salts, organic residues, and color bodies. Common methods include: - Ion exchange to strip ionic impurities - Activated carbon treatment to adsorb color and odor compounds - Distillation under vacuum to separate high-purity glycerine from heavier fractions

3. Refining to Grades After purification, glycerine is typically refined to 99.5% or higher (USP/EP grade) or 80% technical grade, depending on end-use. The final product is clear, odorless, and hygroscopic.

Why This Matters for Buyers

Glycerine from oleochemical splitting is a consistent, high-purity co-product. Unlike biodiesel-derived glycerine (which often contains methanol and catalyst residues), splitting-derived glycerine requires less intensive refining. This makes it a preferred source for pharmaceutical, food, and personal-care applications.

Procurement managers should note that glycerine yields from splitting are roughly proportional to oil throughput—about 10% by weight of the feedstock oil. Supply availability is tied to fatty acid production, not independent glycerine demand, which can affect price stability.

Quality Considerations

Buyers specify glycerine by purity, color (APHA), and residual ash. Splitting-derived glycerine typically meets these specs with minimal variability. However, the feedstock oil quality—especially free fatty acid content and impurities—can influence the sweetwater composition and final refining cost.

Market Context

Glycerine from oleochemical splitting competes with synthetic glycerine and biodiesel co-product. Its production is geographically concentrated near fatty acid plants in Southeast Asia and Europe. Understanding the recovery process helps buyers evaluate supply chain reliability and negotiate specifications with confidence.