Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-12-30
2001-08-14
Vollano, Jean F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S790000
Reexamination Certificate
active
06274777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for removing boron from polyalkyl hydroxyaromatic compounds. More particularly, this invention relates to removing boron from boron trifluoride-catalyzed polyalkyl hydroxyaromatic reaction products to levels below about 10 parts per million (ppm) by filtering the polyalkyl hydroxyaromatic reaction product with a solid filtering agent having an active surface.
2. Description of the Related Art
Boron trifluoride is used as a catalyst in relatively low concentrations for synthesis of liquid hydrocarbons from various olefins. Example applications are alkylation of hydroxyaromatic compounds with various olefins, oligomerization of alpha olefins, and polymerization of low molecular weight olefins. Many of these products find application in lubricating oil additives and gasoline or diesel fuel additives. The boron trifluoride may be introduced into the reaction as a gas or as a complex (for example, boron trifluoride-etherate, boron trifluoride-phenol, and many others). Depending on the particular process, the boron trifluoride is present in the reaction mixture as dissolved gas, or a coordination compound or a mixture of the two forms.
A common feature of all of these processes is that the boron trifluoride must be removed after the reaction, either in a form that can be recycled or in a form that requires disposal. Depending upon the molecular weight and the viscosity of the product, further processing such as distillation can be limited by the presence of boron trifluoride in the product because it will cause depolymerization and cracking of olefin polymers at elevated temperatures. There have been three general techniques used that may or may not involve chemical reaction of the boron trifluoride; adsorption on a particulate solid and separation from the reaction product, extraction using various aqueous solutions and phase separation from the reaction product, and removal by distillation or stripping. Combination of these processes can also be used.
U.S. Pat. No. 4,045,507 describes a process in which 1-decene is oligomerized to a product containing primarily trimer and tetramer in a reactor pressurized with boron trifluoride and containing a coordination compound formed by complexing boron trifluoride with a suitable polar compound such as n-butanol. The resulting oligomer product solution contains boron trifluoride that must be separated from the product. U.S. Pat. No. 4,433,197 discusses a method of selective removal of the boron trifluoride from oligomer product leaving behind the polar compound (n-butanol) used to form the coordination compound. The boron concentration was reduced to a concentration of 13-32 ppm from an initial concentration of 0.5% using silica as a solid absorbent. Recovery of the boron trifluoride was then accomplished by extraction from the silica using n-butanol. A bed of granular polyvinyl alcohol was shown in U.S. Pat. No. 4,384,162 to be another effective adsorbent for nondestructive removal and recycle of boron trifluoride.
U.S. Pat. No. 3,917,733 gives a process scheme for removing boron oxide hydrate from a liquid aromatic hydrocarbon stream and the boron trifluoride off-gas from the alkylation zone using a moving bed of particulate alumina. No mention is made of recovering the boron trifluoride.
Solid reactants that neutralize and extract the boron trifluoride from reaction product have also been widely illustrated in the patent literature. In a 1-olefin oligomerization process, U.S. Pat. No. 4,981,578 discloses that potassium fluoride (KF) in either particulate solid or aqueous solution form can be reacted with the boron trifluoride (BF
3
) in the oligomer product solution. This reaction yields a solid precipitate of potassium fluoborate (KBF
4
) that can then be filtered from the oligomer product. The aqueous solution approach reduced the boron from an initial level of 820 ppm in the oligomer product to 63 ppm after treatment. Similarly, a bed of KF reduced the boron concentration from 820 ppm before treatment to 6 ppm after treatment. This patent teaches that sodium fluoride (NaF) or ammonium fluoride (NH
4
F) may also be used instead of KF.
In a cracked-petroleum-fraction olefin polymerization process, U.S. Pat. No. 3,371,075 illustrates the use of particulate hydrated lime and fuller's earth (more than 90% natural attapulgite and montmorillonite) for neutralization and removal of boron trifluoride catalyst as well as decolorization of the product. The crude product containing the boron trifluoride is mixed with the hydrated lime and fuller's earth and then filtered. Boron was reduced from an initial concentration of approximately 540 ppm to about 4 ppm in the finished product.
In another 1-olefin oligomerization process using boron trifluoride, U.S. Pat. No. 4,956,513 discloses a simple water extraction method for directly removing boron trifluoride. In this method the crude product is washed with water and the phases separated. This is done twice and the aqueous phase washings are combined, then distilled to concentrate the BF
3
—H
2
O complex and recover water and n-butanol overhead. BF
3
can then be recovered by mixing concentrated oleum or sulfur trioxide with the distillation bottoms.
Examples of water extraction applied to boron trifluoride removal from crude polyisobutylphenol, made from alkylation of phenol with polybutene, can be found in U.S. Pat. Nos. 5,300,701, 5,876,468, and British Patent GB 1,159,368. In the examples in these patents, the crude product is mixed with aqueous ammonia to neutralize the BF
3
and then the product is extracted several times with water. The British Patent GB 1,159,368 further teaches that the BF
3
can be neutralized with ammonia gas and then the BF
3
—NH
3
salt filtered from the crude polyisobutyl phenol.
Distillation techniques have also been used for boron trifluoride recovery of the 1-olefin oligomerization reaction mixture. In U.S. Pat. No. 4,263,467, the crude oligomer mixture exits the reaction zone and is then fed downward through a column packed with Berl saddles, a trickle-bed column, while maintaining a pressure of 203 mm of mercury on the column at 23° C. The boron trifluoride is recovered overhead as a gas. The concentration of BF
3
in the product is reduced from an initial level of 2.77% to a concentration after stripping of 680 ppm.
Another distillation approach to recover BF
3
catalyst is disclosed in U.S. Pat. No. 3,000,964 for a phenol alkylation process. In this method, an entrainer constituent such as heptane is refluxed in the crude alkyphenol distillation column. The entrainer distills overhead and carries the BF
3
overhead with it. The entrainer is returned to the column while the BF
3
is absorbed into liquid phenol that is used to transport the BF
3
back to the alkylation reactor. The alkylphenol is the distillation column bottoms product. There is no mention in this patent of residual boron concentration in the product or subsequent treating to remove trace contaminants.
The removal of alkaline catalysts from various polyether polyols is also known in the art. For example, U.S. Pat. No. 4,528,364 to Prier discloses a method of removing alkaline catalysts from polyether polyols and polyalkylene carbonate polyols which comprises dissolving the polyol in an aprotic solvent and then contacting the polyol solution with a sufficient amount of an adsorbent to adsorb the alkaline catalysts, followed by physically separating the adsorbent from the polyol solution. This patent teaches that the process described therein is advantageous as there is no water present to hydrolyze either the polyether polyol or the polyalkylene carbonate polyol. This patent further teaches that preferred adsorbents are aluminum and alkaline earth metal silicates, with magnesium silicate being most preferred. Suitable catalysts taught by this patent include alkali metal borates, alkaline earth metal borates and ammonium borates.
U.S. Pat. No. 4,507,475 to Straehle et al. discloses a process for purify
Gray James A.
Triconnet Thierry
Caroli Claude J.
Chevron Chemical Company LLC
Vollano Jean F.
LandOfFree
Method for removing boron from polyalkyl hydroxyaromatics does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for removing boron from polyalkyl hydroxyaromatics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for removing boron from polyalkyl hydroxyaromatics will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2489374