Cognis launches new cold soak, oxidative stability tests

Posted September 2, 2009

The latest system for cold soak filtration testing has hit the market, part of a trend over recent months that's seen several companies offering solutions for biodiesel producers to meet upcoming enforcement of new ASTM guidelines.

Cognis Corp. announced that it has developed two new analysis capabilities for the Quality Trait Analysis (QTA) System for Biodiesel. "While already providing results in two minutes for 14 properties of biodiesel, the addition of the oxidation stability and cold soak filtration tests to the QTA System enables biodiesel producers and buyers to quickly assess the quality of their product," the company stated.

This helps to reduce inventory carrying costs incurred while waiting on the traditional method of analysis at the same time, improving the throughput of the production facility or distribution terminal. "We are seeing a lot of companies offer their cold soak tests because they see an opportunity to help producers meet new ASTM guidelines," said Raj Mosali of Ohio's Jatrodiesel.

He added that distillation columns are the best way to meet cold soak requirements and that Jatrodiesel has developed its own testing procedures, and will not be looking to external sources to meet its testing needs. Other opinions were that distillation is very expensive, is not a guaranteed safeguard against sterol fall-through and removes natural antioxidants from the fuel. "It's so expensive and you have to use an oxidative stability additive, so I see distillation as self-defeating," said one producer.

The problem in the field, according to Mosali, occurs when biodiesel is not blended promptly after leaving a refinery and experiences low temperatures, even if they are above cloud point. "What happens is that the fuel is heated back up before blending and then sterols fall through," he said. Then that material is blended into the diesel fuel and it can contribute to filter plugging.

Megan Nitz, lab director for Prairie Pride Inc., in Deerfield, Mo., said she needed to see repeatability in the test phases of new cold soak products, the sample size and the result range before selecting a cold soak testing platform to meet the needs of her company's facility.

"The addition of oxidation stability and cold soak filtration to the slate of tests required on each batch of biodiesel significantly increased the analysis time, by as much as 3 days," said Barbara Stefl, Cognis global business director. "With the screening capability of the QTA System for these tests, producers and buyers of biodiesel can have confidence in the quality of the product before the long method is complete."

Since it 2006 launch, the QTA System has conducted over 150 million biodiesel tests for its customers, has participated quarterly in the ASTM Interlaboratory Crosscheck program and recently, has successfully completed an AOCS sponsored round robin of its base capabilities as per the ASTM D6708 requirements.

"The beta versions of oxidation stability and cold soak filtration will be available to existing customers immediately for evaluation," Cognis stated. "The commercial versions will be released during the fourth quarter of 2009."