Patent Application
20080072477
An example of a process for manufacturing a composition in accordance with the present invention involves a reaction producing a DEA amide (i.e. an alkanolamide). The reaction of fatty acid and diethanolamine (DEA) forms DEA amides and water. The by-product water can be removed by vacuum stripping, i.e. distillation.
During the reaction to form the alkanolamide from a fatty acid and DEA, it has been observed that an impurity that is a derivative of piperazine, bis-hydroxyethyl piperazine (BHEP), forms over the course of the reaction. BHEP can precipitate out of the reaction product over time, particularly at concentration over 5000 ppm so it is essential to keep this by-product under control. The formation of this undesirable by-product presents a significant problem in the manufacture of alkanolamides. To limit the level of this impurity, according to the present disclosure, a number of steps are taken during the manufacturing process.
The time at temperature (i.e. reaction time) for this reaction is generally limited to 16 hours and preferably significantly less. Running the reaction beyond 16 hours causes a build up of BHEP and should thus generally be avoided.
It should be noted that this reaction provides an exception to the general trend of alkali number drift in other related products. The alkali number of the product of this reaction generally remains stable because of reaction conditions that leave virtually no free DEA in the product.
An exemplary reaction process can be summarized as follows:
The diethanolamine DEA is kept molten by maintaining at 38±5.5° C. (100±10° F.).
The reactor is set up ready to receive the reactants (a suitable reactor may be a R3200 reactor).
The reactor is charged with the fatty acid, i.e. isostearic acid (e.g. isostearic available under trade name Prisorine™ 3501, 3502, 3503 or 3505 (ex Uniqema)). The isostearic acid can be added at the maximum rate for the particular reactor. Obviously the amount of reactants will be changed to suit the volume of the particular reactor, whilst maintaining the desired ratio of reactants.
The agitator is set to run at a suitable rate to achieve satisfactory mixing of the mixture.
The reactor is heated to 138° C. (280° F.). The reactor heater can then be switched off. The exothermic reaction of the fatty acid and DEA will elevate temperature to the desired level for the reaction.
The reactor is charged with DEA, to give a molar ratio of 1:0.7 (isostearic acid : DEA). The DEA should be added slowly, e.g. at a rate of around 25 lbs/min for a total DEA load of 7690 lbs (3488 kg)—which would correspond to a isostearic acid load of 32310 lbs (14656 kg).
The reaction will be heated to 149° C. (300° F.) at rate of 0.8° C./min (1.5° F./min) and the water distillation is started. The heating is generally provided by the exothermic reaction between the fatty acid and DEA, but additional heating or cooling can be provided if required to achieve and/or maintain the desired temperature. Excessive foam build up at the beginning of distillation should be watched for.
When the temperature reaches 149° C. (300° F.) the time is recorded. This is used to track the total time at temperature for the batch (i.e. “reaction time”).
The reactor is held at 149° C. (300° F.) and the vacuum is brought down to the desired level (e.g. below 50 mm Hg). It is important to observe for excessive foam build up at the beginning of vacuum ramp.
Once full vacuum has been reached, the conditions are held. The temperature should not be allowed to exceed 153° C. (307.5° F.).
The mixture within the reactor is sampled regularly to check reaction progress (e.g. hourly).
When each sample is taken the total time for the batch at 149° C. (300° F.) is recorded. The results of the sample analysis are logged. Suitable acid and alkali number end parameters for the reaction product are:
Acid Number: 2.0 max
Alkali Number: 30 max
Each sample is compared with the following parameters to determine if the reaction end point is reached. If one of the three batch parameters is met then the next step in the process should be proceeded to. If none of the three following parameters are met, the reaction conditions should be maintained and the batch re-sampled later. There are, in general no running adjustments to the batch. The reaction parameters used to mark the end point are as follows:
The acid number is 1.2 or less;
The acid number is 2.0 or less and within 0.1 units of the acid number of the previous sample; or
The total time for the batch at 149° C. (300° F.) reaches 16 hours.
Once one of the three criteria above is met, the mixture is cooled and the vacuum is broken.
The reaction mixture is again sampled to check the final batch properties and the results logged. The results should be within the following parameters:
Assuming the batch is within specification, the reaction product is then transferred from the reactor to barrels or other containers as appropriate.
Such a method as described above is capable of producing an alkanolamide-containing composition with a BHEP content of less than 3000 ppm as determined by gas chromatography. It may be possible that further optimization of the process may result in even lower levels of BHEP, and such an optimized process is within the scope of the present invention.
As a control reaction the process described above was repeated with the following differences:
A stoichiometric mixture of DEA and isostearic acid was used (i.e. a 1:1 molar ratio).
The DEA was not added slowly, but rather at the maximum rate achievable with the reactor. Otherwise the reaction conditions were identical.
The product of this reaction typically contains at least 6000 ppm BHEP. When the product is stored in barrels for a period of two weeks, significant deposits of BHEP developed on the sides of the barrel.
The composition as produced in the above method is particularly suitable for use as a fuel additive for gasoline fuel. To form a modified fuel between 1 and 2% by volume of the composition can in one embodiment be added to gasoline fuel.
The modified fuel produced has several advantageous properties, including but not limited to, reducing friction within the engine in which it is used, thus increasing efficiency.
Three engine valve sticking experiments were performed. These had two levels of BHEP contamination in the diethanolamide fuel additive. One level was 1965 ppm of BHEP and the other two experiments had 3664 ppm of BHEP in the gasoline. The sample containing the 1965 ppm BHEP was found to provide the best passing rate on all relevant fuel and engine compression tests. Modifications to the described examples may be made without departing from the scope of the present invention.
