Title of Invention

AN IMPROVED PROCESS FOR THE FRACTIONATION OF HARD MICROCRYSTALLINE WAXES TO PRODUCE DIFFERENT MELTING GRADE WAXES

Abstract

The present invention relates to an improved process for the fractionation of hard microcrystalline waxes to produce different melting grade waxes. High melting waxes having a narrow melting range are required in many industries like paper coating, lamination, cosmetics, leather, rubber, textiles and tyre manufacture. This new process for the production of such waxes is simpler, cost effective and could be set up with a very low investment. The process consists of percolating fractionating solvent having a mixture of higher ketone and higher aromatic solvent in a ratio through a fixed bed of powdered or flakes of hard wax packed in the percolation column at a temperatures ranging from 20 to 80°C or successively at a uniform temperature interval selected from 5 °C, 10 °C and 15 °C and recovering different melting grade waxes by distilling the solvent from the eluants obtained at different fractionating temperatures.

Full Text

The present invention relates to an improved process for the fractionation of hard microcrystalline waxes to produce different melting grade waxes High melting waxes having a narrow melting range are required in many industries like paper coating, lamination, cosmetics, leather, rubber, textiles and tyre manufacture. This new process for the production of such waxes is simpler, cost effective and could be set up with a very low investment. The commonly employed processes for production of such waxes involves fractionation by vacuum distillation or by fractional crystallization. Reference may be made to Kustevalov et. al; Neftepererab Neftekhim 10, 12, 1984; wherein petroleum waxes have been fractionated by distillation under vacuum at high temperatures. The drawback of t his process is this requirement of vacuum conditions and maintenance of high temperature, which in turn requires equipment suitable to withstand such drastic conditions. Reference may also be made to McLaren et.al; Tappi 34(10), 462, 1951 wherein waxes of desired melting grade are produced by multistage fractional crystallization. The process involves chilling of wax solvent slurry from a high temperature. The drawback of this process is the requirement of costly refrigerating system. The main objective of the present invention is to provide an improved process for the fractionation of hard microcrystalline waxes to produce different melting grade waxes which eliminates the drawbacks as detailed above. In the drawing accompanying this specification Figure 1 represents the percolation column employed for the solvent fractionation of hard wax. Accordingly (the present invention provides an improved process for the fractionation of hard microcrystalline waxes to produce different melting grade waxes which comprises, i) percolating fractionating solvent having a mixture of higher ketone and higher aromatic solvent in a ratio of 1:1 to 10:1 (by weight) through a fixed bed of powdered or flakes of hard wax packed in the percolation column at a temperatures ranging from 20 to 80 °C or successively at a uniform temperature interval selected from 5 °C, 10°C and 15 °C ii) recovering different melting grades waxes by distilling the solvent from the eluants obtained at different fractionating temperatures. In an embodiment of the present invention the solvent used is mainly a mixture of higher ketone and aromatic solvent. In another embodiment of the present invention the higher ketone used in solvent mixture is selected from the group consisting of methyl ethyl ketone and methyl isobutyl ketone. In yet another embodiment of the present invention the aromatic solvent used in solvent mixture is selected from the group consisting of benzene, toluene and xylene. In still another embodiment of the present invention a new fractionating process for different grade waxes which eliminates the requirement of refrigeration and vacuum distillation. The process involves fractionation of high melting wax in a jacketed percolation column. High melting wax refers to waxes normally melting above 85 °C, most of which are of petroleum origin derived from tank bottom sludges/sucker rod scrappings of crude oil. The percolation column is double walled jacketed column made of glass but could be of any material that can withstand temperature upto 120 °C. The column can be of any length but the ratio of the column length to the inner diameter is as shown in Figure 1. The desired column temperature is maintained by circulating water/ethylene glycol/paraffin oil. The column has an orifice at the bottom, which permits the solvent to trickle down. A stop-cock is provided to adjust the rate of flow. The column is packed with weighed quantity of hard wax taken in powdered/flake form to a height of approximately 2/3rd of the column length. The temperature of the column is maintained at 20 °C. Fractionating solvent is a mixture of higher ketone (e.g. isobutyl-methyl ketone, ethyl methyl ketone etc.) and an aromatic solvent (e.g. benzene, toluene, xylene etc.), the aromatic solvent varying from 10 to 30% in the solvent mixture. A feed solvent ratio ~5ml/g is maintained. The solvent is added slowly to the column from top and the stop cock is adjusted to maintain a flow rate of approximately 2ml/s. The eluant is collected and after the elution has stopped completely, the eluant is distilled to recover the wax fraction extracted with the eluant. The wax remaining in the column is extracted and distilled. The column is refilled with wax and the solvent percolated at different temperatures to collect the two fractions. Alternatively fractionating solvent is percolated at 20 °C and only the eluant is distilled to recover the wax fraction. The temperature of the column is raised by 5 or 10 or 15 °C, depending upon the melting range of the wax required. The same volume of fractionating solvent, as employed for fractionation at 20 °C is percolated and the eluant distilled to recover the next grade of wax. The temperature of the column is raised successively in steps of temperature interval selected to a temperature ~10°C below the drop melting point of parent feed wax. The percolation of same volume of fractionating solvent as employed for fractionation at 20 °C, is carried out at each temperature and the wax recovered separately from the eluant collected at each fractionating temperature. If wax of wider melting range is desired the fractionation is carried out at intervals of 10 or 15 °C. The increase in percentage of aromatic solvent from 10 to 30 % in the fractionating solvent increases the melting point of the wax fraction obtained at a particular temperature. The following examples are given by way of illustration and therefore should not be considered to limit the scope of present invention. In the following examples the waxes have been analyzed for carbon number distribution by gas chromatography Example 1 The yield, melting point and carbon range of the different waxes obtained by solvent fractionation at intervals of 20 °C of microcrystalline wax derived from Bombay High Crude oil tank bottom sludge using a 70:30 MIBK: Toluene fractionating solvent is shown below. Feed Microcrystalline Wax Powder Form, m.pt 92.4 °C Solvent MIBK : Toluene Mixture (70 : 30 by weight) Approach Fractionation at single temperature (Figure Removed) • Pour point The wax fraction having pour point/melting point 27 °C - 65 °C are potential source for utilizations in manufacture of petroleum jelly. The wax fraction with melting point 96.8-108.0°C and having different carbon ranges can find use in paper coating and many other applications. Example 2 The yield, melting point and carbon range of the different waxes obtained by solvent fractionation at intervals of 20 °C of microcrystalline wax derived from Bombay High Crude oil tank bottom sludge using a 90:10 MIBK: Toluene fractionating solvent is shown below. Feed Microcrystalline Wnx Powder Form, m.pt. 92.4 °C Solvent MIBK : Toluene Mixture (90:10 by weight) Approach Fractionation at single temperature (Figure Removed) • Pour Point The two examples, examples 1 and 2 show that by variation of solvent composition and temperature of fractionation waxes having properties required by many industries can be produced . Example 3 The yield and melting point of the different waxes obtained by successive solvent fractionation at intervals of 10 °C, of microcrystalline wax derived from Bombay High Crude oil tank bottom sludge using a 70:30 MIBK: Toluene fractionating solvent is shown below. Feed Microcrystalline Wax Powder Form, m.pt. 92.4 °C Solvent MIBK : Toluene Mixture (70 : 30 by weight) Approach Successive fractionation at intervals of 10°C (Figure Removed) Pour Point The example shows that a good fractionation has been achieved. Waxes of desired melting point with small carbon range, e.g wax with m.pt of 100 °C can be prepared by this process. These high melting waxes may find use in tyre industry, as hot melt adhesives etc. The main advantages of the present invention are 1. A good fractionation can be achieved 2. Use of readily available solvents 3. The solvent could be recycled for further use 4. No requirement of vacuum conditions and refrigeration 5. Process parameters can be varied to produce wax of desired properties 6. A low initial investment for setting up the production unit 7. Suitable for small capacity plants producing microcrystalline waxes from tank sludges We claim: 1. An improved process for the fractionation of hard microcrystalline waxes to produce different melting grade waxes which comprises, i) percolating fractionating solvent having a mixture of higher ketone and higher aromatic solvent in a ratio of 1:1 to 10:1 (by weight) through a fixed bed of powdered or flakes of hard wax packed in the percolation column at a temperatures ranging from 20 to 80°C or successively at a uniform temperature interval selected from 5 °C, 10°C and 15 °C, ii) recovering different melting grades waxes by distilling the solvent from the eluants obtained at different fractionating temperatures. 2. An improved process as claimed in claim 1, wherein the solvent used is mainly a mixture of higher ketone and aromatic solvent. 3. An improved process as claimed in claims land 2, wherein the higher ketone used in solvent mixture is selected from the group consisting of methyl ethyl ketone and methyl isobutyl ketone. 4. An improved process as claimed in claims 1 to 3, wherein the aromatic solvent used in solvent mixture is selected from the group consisting of benzene, toluene and xylene. 5. An improved process for the fractionation of hard microcrystalline waxes to produce different melting grade waxes substantially as herein described with reference to the examples and drawings accompanying this specification.

Documents:

406-DEL-2002-Abstract-(15-02-2010).pdf

406-del-2002-abstract.pdf

406-DEL-2002-Claims-(15-02-2010).pdf

406-del-2002-claims.pdf

406-del-2002-correspondence-others.pdf

406-del-2002-correspondence-po.pdf

406-del-2002-description (complete).pdf

406-del-2002-drawings.pdf

406-DEL-2002-Form-1-(15-02-2010).pdf

406-del-2002-form-1.pdf

406-del-2002-form-18.pdf

406-del-2002-form-2.pdf

406-DEL-2002-Form-3-(15-02-2010).pdf

406-del-2002-form-3.pdf

Correspondence-Others (15-02-2010).tif