Patent Publication Number: US-6670495-B2

Title: Process for producing ferrous picrate and a fuel additive containing ferrous picrate from wire

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a process for producing ferrous picrate and a fuel additive containing ferrous picrate from wire. 
     2. Description of the Related Art 
     There are many patents dealing with process for producing ferrous picrate fuel additives. 
     These includes U.S. Pat. Nos. 2,506,539; 3,282,858; 4,073,626; 4,099,930; 4,129,421; 4,265,639; 4,424,063; 5,087,268; 5,359,103; 5,720,783; and 5,925,153. 
     Only U.S. Pat. Nos. 5,087,268 and 5,925,153 employ metallic iron; and these both utilize powdered elemental iron. The large surface area of powdered elemental iron facilitates the desired reaction. 
     Surprisingly, though, another inventor, whose invention is owned by same entity that owns the present invention, discovered that favorable reaction rates can be obtained using steel wool. Such invention is the subject of a patent application filed concurrently with the present application. 
     SUMMARY OF THE INVENTION 
     And even more surprisingly, the present inventor has discovered that wire comprised of an iron alloy can produce favorable reaction rates. 
     Preferably the wire is loosely coiled and either suspended in the reaction vessel or placed upon the bottom of the reaction vessel. 
     The product produced by this process does not contain the particles of iron found in fuel additives produced from iron in accordance with the processes of the prior art. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present process can employ any solution of picric acid in a solvent that is known in the art for reacting with iron to produce ferrous picrate. 
     Preferably, however, a solution that is approximately three percent picric acid (i.e., three grams of picric acid per one hundred milliliters of solvent) is produced by dissolving picric acid in a solvent. Acceptable solvents are an aromatic solvent such as benzene, toluene, or xylene or a high aromatic petroleum fraction such as Solvent 100, although all other aromatic solvents and high aromatic petroleum fractions disclosed in the art to be used for a similar purpose are also acceptable and will hereinafter simply be termed aromatic solvents and high aromatic petroleum fractions used in the art. A practical percentage which can be achieved within a reasonable time is 2.8 percent. The more picric acid which is dissolved, the better. It is, however, extremely difficult to dissolve significantly more than three percent. The percentage of picric acid which has been dissolved is determined analytically, preferably by titration. 
     After having combined the picric acid with the solvent, water is removed from the solution using any technique that is well known in the art. Preferably, though, settling is allowed to occur so that the water is vertically separate from the solution of picric acid in solvent. Then the top layer can be removed by decantation or siphoning, or the bottom layer can be removed by draining. One of the various alternate methods for removal is centrifugal separation; another is azeotropic distillation. 
     The solution resulting from this preferred mixture is termed a pre-mix (as also, for the purposes of this patent application, is any solution of picric acid in a solvent, after such solution has been dewatered, that is prepared in accordance with the art of preparing ferrous picrate; such solution before dewatering is termed a precursor to the pre-mix solution) and has subsequently added to it an aliphatic alcohol. A non-exclusive list of acceptable aliphatic alcohols includes ethanol, isopropanol, and butanol. Butanol is preferred. It is preferable to add the aliphatic alcohol to the pre-mix rather than adding the pre-mix to the aliphatic alcohol in order to prevent the precipitation of some of the dissolved picric acid. Preferably, 25 percent butanol is combined with 75 percent pre-mix on a volume basis. 
     To the resultant solution some water, preferably 0.1 to 0.5 percent and most preferably approximately 0.1 percent, is added. This is to control the quantity of water since some is necessary for the desired reaction to occur, but an excess amount causes instability and degradation in the product. 
     Preferably, the solution is agitated after the initial combination of ingredients and each addition of an ingredient. 
     Wire composed of an alloy of iron is suspended in the solution, either any solution known in the art for producing ferrous picrate from iron or the preferred solution discussed above, or is placed upon the bottom of a reaction vessel that contains the solution. Preferably the wire is loosely coiled, at least when placed upon the bottom of a reaction vessel. Suspension of the wire can be accomplished using any material that will not react with the substances in the solution; stainless steel is, however, preferred for this purpose. 
     The wire preferably, but not necessarily, contains 0.2 to 5.0 percent, by weight, of carbon, manganese, phosphorous, sulfur, and silica alloyed with the iron. 
     The solution is preferably agitated after the wire has been introduced. The product resulting from reaction of the picric acid with the wire to produce ferrous picrate is termed a “concentrate.” A preferred concentration of iron in the concentrate is 1425 ppm. 
     It has experimentally been determined, however, that degradation of the product over time is minimized, i.e., stability is maximized, when the solution contains approximately 1.9 percent free (dissolved but unreacted) picric acid and 15 to 16 percent aliphatic alcohol, preferably butanol. A selected concentration of iron less than that of the concentrate is then achieved by combining the requisite amounts of concentrate, pre-mix, and aliphatic alcohol to attain the desired concentration of iron while also containing approximately 1.9 percent free picric acid and 15 to 16 percent of the alcohol. This is termed the final product. 
     Either the concentrate or the final product is appropriately termed a fuel additive. 
     A further decrease in degradation is caused by the fact that the use of wire instead of small particles of iron, such as filings or powder, precludes small particles of iron from being in the concentrate and the final product. 
     The following example illustrates this process. 
    
    
     EXAMPLE 1 
     A mixture of 22.5 parts of picric acid and 750 parts of Solvent 100 was agitated in a container until the picric acid was dissolved. Then 250 parts of butanol were added to the solution. This was then thoroughly mixed. Next, 1 part of tap water was added to the solution; and the contents were again thoroughly mixed. Then 8 parts of steel wire were suspended in the solution. The contents of the container were then agitated for 1 hour and 35 minutes to produce a ferrous picrate solution containing 1,425 parts per million of ferrous iron. 
     As used herein the term “preferable” or “preferably” means that a specified element or technique is more acceptable than another but not that such specified element or technique is a necessity.