Cetane improver comparison provokes counter-attack

Diesel Fuel News, Jan 7, 2002 by Jack Peckham

A survey by U.S. diesel additives blender Amalgamated Inc. of competing cetane improvers claims to show that only Amalgamated's product lives up to advertising claims, while others supposedly exaggerate performance.

But companies identified by Amalgamated as failing to live up to advertised claims told us that the Amalgamated survey itself is seriously flawed and fails to portray the competitive situation accurately.

Amalgamated says it took 21 different "well-known diesel fuel additives either promoting a cetane number gain or alluding to that benefit" for cetane tests at prestigious Southwest Research Institute.

For the tests, Amalgamated said it used a single 43.4 cetane base fuel, with ordinary distillation range, 400 ppm sulfur, ordinary API gravity and viscosity and typical carbon residue, flash point and water content. Then it blended the additives from competitors at the "recommended treat rate" stated by the companies making the products, Amalgamated claims.

In Amalgamated's report on the survey results, it cites a chart claiming to be the "only industry-accepted 'response data curve' for predicting the engine cetane number change" with 2-ethyl-hexyl-nitrate (2EHN), a very common cetane additive. However, this claim is disputed by other cetane manufacturers and blenders who cite several, similar cetane response curves published in peer-reviewed technical journals.

Assuming that this presumably standard cetane response chart is accurate, then it should be simple to calculate the pounds per thousand barrels (ptb) additive rate for 2EHN, Amalgamated says. "High-responding fuels" would required only about one-quarter the 2EHN for "low responding fuels," the Amalgamated report says.

Amalgamated's survey and test reports claim to confirm these expectations. The resulting tests, performed at SwRI, supposedly show that only Amalgamated met advertised cetane boosts. But only one base fuel was used in Amalgamated's test.

Of possibly greater importance, several competitors told us, is that Amalgamated shows no chain-of-custody proof for the products tested, gives names of products that at least two competitors told us don't exist, or in some cases fail to state accurately what the companies themselves claim for their products.

Competitors also take issue with numerous statements, such as Amalgamated's claim that 2EHN is the "only universally accepted chemical additive available for increasing engine cetane number (diesel fuels and fuel oils)," or that "a single manufacturer in Europe produces the majority of this chemical product for all world markets."

In fact, 2EHN has more than one major producer and has several competitors, including di-tert-butyl peroxide (DTBP), iso-octyl nitrate, di-nitro propane and iso amyl nitrate, Octel-Starreon (marketer of DTBP) says.

Amalgamated's claim about the "single manufacturer" in Europe dominating world 2EHN sales is also exaggerated, according to Octel-Starreon and Ethyl, a major supplier of 2EHN.

What's more, several of the tested products don't make specific cetane number claims, yet Amalgamated lumps them in with other cetane improvers. "To infer they are not valid in claims due to no cetane performance is of no relevance and can unjustifiably taint the consumer's perception of a quality product," as Octel-Starreon's R&D director David Daniels told us.

Amalgamated's survey claims to show that one Octel-Starreon product that was supposed to increase cetane doesn't live up to its advertised claim. But Octel-Starreon told us that the product supposedly in question doesn't exist by the name Amalgamated cites, and in any case wasn't proven by any verified, independent chain-of-custody to be one of Octel's cetane improvers. If it was an Octel product, it might in fact have been a cold-flow improver, rather than a cetane additive, Octel-Starreon told us.

Another additive maker claimed to be exaggerating cetane response in the Amalgamated survey is Schaeffer Manufacturing. But Schaeffer spokesman Hoon Ge told us that the cetane improver alleged to be in question can indeed boost cetane by two to four numbers on fuels that have greater cetane response. Amalgamated "only did one fuel test, and it bothers me that everyone except Amalgamated supposedly is wrong. Maybe if I did my own test, I'd pick a fuel that does best with my additive," Ge said.

Amalgamated's survey report shows side-by-side tests of straight 2EHN addition at various treat rates (in pounds per thousand barrels, ptb). These results supposedly show that the cetane response is straightforward: the more 2EHN ptb, the higher the cetane response, exactly as Amalgamated claims for its own additive package. The "rule of thumb" is 100 ptb 2EHN yields about 1 cetane number improvement, according to Amalgamated.

Still, the official American Society for Testing & Materials D-613 cetane test standard shows that a supposed 44 cetane fuel (very close to Amalgamated's 43.4 base fuel) itself has a 0.9 repeatability limit (almost one full cetane number) and a 3.3 reproducibility limit. 5 many of the products Amalgamated claims t show as not living up to advertising are close to repeatability and well within reproducibility competitors point out. What's more, Amalgamated may very well have cherry-picked a fuel for testing that it knew had a certain response to certain levels of 2EHN, as well as an identical response to its own additive, prior to the test comparison at SwRI, competitors charged.