[001] The present invention relates to a process for removal of metals in oils/fats. This
invention particularly relates to a process to reduce metals from oils/fats preferably from vegetable oils/animal oils/fats. It reduces the total metal content sufficiently below 1 ppm in order to make them suitable for hydroprocessing/Fluid Catalytic Cracking (FCC) feedstocks.
BACKGROUND OF THE INVENTION AND PRIOR ART
[002] This invention relates to a process for demetallation in oils/fats most preferably
vegetable oils/animal oils/fats. The metal mainly includes P, Na, K, Ca, Mg, Cu, Fe etc. The
present invention is an environment friendly, industrial effluent free novel process, which
includes avoidance of any water washing process during counter-current treatment with recycled
and fresh clay in one or more stages. The inventive process also avoids usage of any expensive
industrial chemicals that are used in prior art. The process finally includes treatment of oils/fats
with ion exchange resin to make the oils/fats suitable for feedstocks for catalytic refining
processes, such as hydroprocessing/FCC. The present invention increases the shelf life of the
oils/fats by reducing total metal contaminant below 1 ppm. Thereby the present invention
provides a very cost effective process to produce total metal contaminant free oils/fats.
[003] Conventionally, biodiesel is produced by transesterification of vegetable oil,
which are triglycerides of C14 to C22 straight-chain unsaturated carboxylic acids. In the process, triglycerides are converted into Fatty Acid Methyl Esters (FAME) with an alcohol in the presence of a catalyst. The process though simple suffers from several disadvantages. The removal of glycerin needs separation, excess of methanol is necessary to complete the reaction and subsequently its recovery. There are steps of water washing to remove the caustic and this adds to the plant effluent. Moreover if the vegetable oil is rancid, an additional step of esterification is necessary. The process is suitable only for oils having low Free Fatty Acid (FFA) <0.5%.
[004] Biodiesel has several inherent problems such as high density of about 0.88 g/cc
(diesel density 0.825 to 0.845 g/cc) and narrow boiling range 340°C+. Any further reduction in T-95 specification will affect refiner's profitability adversely due to requirement of production of

lighter diesel for enabling blending of biodiese.. The presence of oxygen in biodiesel also results in higher emissions ofNOx. Also, FAME is not well accepted by auto industry in all proportions as these are responsible for injector coking.
[005] To overcome the above difficulties, Refiners are exploring hydroprocessing route,
as an alternative option, and produce renewable fuels such as diesel, ATF, gasoline etc from
vegetable oils/animal oils/fats. This will enable integrated refining and marketing companies to
meet stipulation of blending biofuels in diesel that may be mandated by the Government in near
future. The process results in improvement in quality of diesel particularly w.r.t. cetane number
and density. The process is capable of handling different vegetable oils; however, it is required to
pre-treat the oil to remove metals below 1 ppm to avoid faster catalyst deactivaiion.
[006] Vegetable oils and animal oils/fats typically contain about 50 - 800 ppm of metals
such as P, Na, K, Ca, Mg, Cu, Fe etc. In crude vegetable oil, these metals can originate from contamination by soil and fertilizers. The phosphorous is present as phosphorous based compounds (phosphaiides). The presences of these compounds impart undesirable flavor, color, and shorten the shelf life of oil.
[007] Metals such as Fe and Cu are usually resulted from corrosion and mechanical
wear at the mills and refineries. These metals are prooxidant and thus, detrimental to the oil
quality. Trace metals may be present as complexes surrounded by proteins, phospholipids and
lipids or non-lipid carriers. These metals catalyze the compositions of hydroperoxides to free
radicals. Fe increases the rate of peroxide formation while Cu accelerates the hydroperoxides
destruction rate thereby increasing the production of secondary oxidation products.
[008] Conventionally, water acid degumming is used to remove phosphaiides from
vegetable oils and animal olis/fats. This process is being used as part of biodiesel manufacturing plant. In this process oil is heated up to about 70-90°C followed by mixing of 0.05 to 0.1 % phosphoric acid in a Continuous Stirrer Tank Reactor (CSTR). The residual acid is neutralized in subsequent CSTR by mixing with caustic followed by removal of gums by centrifugaiion and water washing. The process requires huge quantity of water for water washing and its disposal. Caustic used for neutralization of residual phosphoric acid also reacts with free fatty acids present in oils and fats and forms stable emulsion which is very difficult to break and requires longer time. The process is not suitable for removal of rrace metals below 20 ppm.

[009] US Patent No. 5,239,096 disclosed a process for reducing non-hydratable gums
and wax content in edible oils. The process involves mixing with 0.01 to 0.08 % acid (in the form 10-15% aqueous solution), adding 1-5% base solution followed by slow mixing for 1-4 hrs, separating gums and water washing of oil. As discussed above the process will suffer due to drawbacks of water washing and neutralization steps.
[010] US Patent No. 6,407,271 disclosed a method for eliminating metals from fatty
acid substances and gum associated with said metals. Method comprises mixing of vegetable oil with aqueous solution of salt of polycarboxylic acid (Sodium salt of ethylenediaminetetraacetic acid, EDTA) in the droplets or micelles in the weight ratio above 3. The aqueous phase is separated from oil by centrifuging or ultra filtration. Process uses very expensive chemicals and huge quantity of water about 33% of vegetable oil.
[011] US Patent No. 6,844,458 disclosed improved refining method for vegetable oils.
In this method aqueous organic acid and oil subjected to high and low shear followed by
centrifuge to remove gums. As cited in examples process uses about 10% water of oil quantity to
dilute the acid solution and treated oil still contain about 20 ppm of metals.
[012] US Patent No. 7,494,676 disclosed a pretreatment process comprising of a)
enzymatic degumming with or without citric acid and sodium hydroxide b) bleaching with 2-4%
bleaching earth and 0-1% activated carbon c) de~axing at low temperature of 18-20 °C with
gentle stirring for about 12-18 hrs to achieve < 5 ppm phosphorous. The process uses up to 2.5%
of water and centrifuge for separation of gums. As described above, caustic react with free fatty
acids present in oil and fats and forms stable emulsion which is very difficult to break and
require longer time. The complete process takes very long time of about 15-20 hrs. Hence the
size of dewaxing vessel will be huge and also require high energy for stirring. Moreover, process
did not discuss the removal of other metals such as Fe, Cu, Na, K, Ca, Mg etc. present in the oil.
[013] Hence, there is need of simple and suitable process which can avoid use of water
and expensive chemicals and reduce total metal contaminant below 1 ppm to make the oil or fat
suitable for catalytic processes such as hydro processing/fluid catalytic cracking.
[014] There is also a need to provide ~ dem7tallation process suitable for removal of
total metals below 1 ppm in vegetable oils such as jatropha carcass oil, karanj oil, castor oil, ricebran oil, soybean oil, sunflower oil, palm oil, rapeseed oil etc and animal oil/ fats such as fish

[015] The present invention provides a simple and cost effective demetallaiion process
for removal of total metals below 1 ppm from vegetable oils/animal oils/fats by avoiding usage of water washing and centrifuging steps. Since the present invention avoids water washing, it makes the process environment friendly and effluent free. The synergistic effect due to simultaneous usage of phosphoiic and citric acid enhances the performancss and reduces total quantity of the acids required in comparison to any individual acid. The clay used in the present invention is recycled by way of counter current recycling to minimize the total consumption of the clay. The advantage in the present invention is achieved by recycling of the clay from subsequent stage to the previous stage and charging the final stage with fresh clay. Finally, the oil is treated with ion exchange resin to reduce total metals below 1 ppm. The invention does not involve the use of water washing and centrifuging steps in this process.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
[016] The above and/or other aspects of the present invention will be made more
apparent by describing certain exemplary embodimenss of the present invention with reference to
the accompanying drawings, in which:
[017] Fig.! shows an exemplary process flow schematic embodying the disclosed
techniques.

DETAIL DESCRIPTION OF THE INVENTION
[018] The present invention provides an environmen. friendly process for removal of
total metals below 1 ppm in vegetable oils/animal oils/fats. Phosphoiic acid and citric acid are simultaneously used so that their synergistic effect reduces the requirement of the said acids. The process is conducted without involvement of water washing step, making the process effluent free. It reduces the consumpiion of clay by recycling.
[019] The mixture of phosphoric acid and citric acid has a synergistic effect which
reduces the acid requiremen.. The proportion of these acids required for the process is very low and ranges from 0.01 to 0.10 wt%. Preferred proportion for phosphoric acid is 0.02 to 0.08 wt% and more preferred proporiion is 0.03 to 0.05 wt% with respect to the oils/fats used; corresponding proportions of citric acid is 0.01 to 0.10 wt%, preferred proporiion is 0.02 to 0.08 wt% and more preferred proportion is 0.02 to 0.04 wt%. The process is carried out at a temperature of 40-100°C under constant agitation. The proportion of clay used ranges from 0.5 to 5 wt% and the temperature of the clay ranges from 80-100°C for 30-90 minutes under stirring after acid mixing. The clay treatment is preferably done in multiple stages with fresh clay and/or recycled clay in counter-current movemen.. The fresh clay can be added in all stages of clay treatment and spent clay is withdrawn from each stage of clay treatment or fresh clay is added in the last stage of clay treatment and spent clay is withdrawn from first stage of clay treatment.The recycled clay is separated by employing hydrocyclone separator. Spent clay is separated by employing filter press. For bringing down the metal content even below 1 ppm according to this invention the acid and clay treated oils/fats are required to be finally treated with ion exchange resin. The ion exchange resin is selected from one or more of styrene, crosslinked polystyrene, crosslinked polyacryiic crosslinked polymethacrylic resin etc. These resins can be commercially available and are in the form of gel, macro porous or isoporous etc. The said ion exchange resin treatment is carried out using two beds of ion exchange resin operated in swing mode of demetallation and regeneraiion. The regeneraiion of the ion exchange resin is carried out by circulation of an alcohol like isopsopropyl alcohol and dilute solution of an inorganic acid like HCl.

[020] The oils/fats can be selected preferably from the vegetable and/or animal sources.
The edible and non-edible vegetable oil is preferably selected from one or more of jatropha carcass oil, karanj oil, castor oil, ricebran oil, soybean oil, sunflower oil, palm oil, rapeseed oil etc. The animal oil/fat is preferably selected from one or more of fish oil, lard etc. There is no need of any water washing of treated oils/fats in the process. The metal contaminanss can be one or more ofP, Na, K, Ca, Mg, Cu, Zn, Mn, Fe and the like.
[021] It has been surprisingly found in the process that simultaneous use of phosphoric
and citric acids reduces total quantity of the acids required in comparison to any individual acid. It has been also found in the process that the used clay can be recycled, hence its total consumption is minimized. Further, it has been found that use of ion exchange resin reduces total metal below 1 ppm.
[022] The invention is now more specifically described with the help of a schematic
demetallation process flow scheme shown in Fig 1. In this process vegetable oil is heated up to 50-60°C and sent to eSTR-1, where 0.02 to 0.05% phosphoric, citric or both acids are added and temperature raised up to 80-100°C and mixed for 30 to 60 minutes with gentle stirring. After
■ ; V
completion of mixing in eSTR-1, the mixture is sent to eSTR-2, maintained at 80-100°C, where fresh or recycle clay from eSTR-3 is continuously added under mixing for 30 to 60 minutes. After completion of mixing in eSTR-2, the mixture of clay and oil is separated employing a filter press. The spent clay withdrawn from filter press is sent for disposal after recovery of gums and oil. The oil from filter press is sent to eSTR-3, maintained at 80-100°C, where fresh or recycle clay from CSTR-4 is continuoully added under mixing for 30 to 60 minutes. After completion of mixing in eSTR-3, the mixture of clay and oil is separated employing a hydrocyclone separator. The recycle clay withdrawn from hydrocyclone separator is sent to eSTR-2 and oil is sent to eSTR-4. In eSTR-4 fresh clay in the range from 0.5 to 3.0 wt% of oil is added and mixing continued for 30-120 minutes. After completion of mixing in eSTR-4, the mixture of clay and oil is separated employing a hydrocyclone separator. The recycle clay withdrawn from hydrocyclone separator is sent to eSTR-3 and treated oil containing below 5 ppm metal is sent to ion exchange resin to reduce metal below 1 ppm. In the similar fashion more than 3 stages of clay mixing may be employed. The process avoids use of water washing, minimizes total acid consumpiion and also reduces use of clay with recycling.

Examples: Example-l
[023] 200 gm jatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing of 0.2 gm phosphoric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raw jattopha carcass oil and treated oil is given below in Table-1.

Example-2
[024] 200 gm aatropha carcass oilcontaining 313 ppm of metals was heated up to 50°C
followed by mixing of 0.1 gm phosphoric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raw jatropha carcass oil and treated oil is given below in Table-2.


Example-3
[025] 200 gm jatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing of 0.2 gm citric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raw jatropha carcass oil and treated oil is given below in Table-3.


Example-4
[026] 200 gm jatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing of 0.1 gm citric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raw jatropha carcass oil and treated oil is given below in Table-4.

Example-5
[027] 200 gm Jatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing of 0.1 gm each of phosphoric acid and citric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raw jatropha carcass oil and treated oil is given below in Table-5.


Example-6
[028] 200 gm jatropha carcass oilcontaining 313 ppm of metals was heated up to 50°C
followed by mixing 0.10 gm phosphoric acid and 0.04 gm of citric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raw jatropha carcass oil and treated oil is given below in Table-6.


Example-7
[029] 200 gm jatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing 0.10 gm phosphoric acid and 0.02 gm of citric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 10 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the clay treatment is performed with another 10 gm of clay. The metals content of raW jatropha carcass oil and treated oil is given below in Table-7.

Example-8
[030] 200 gmjatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing 0.10 gm phosphoric acid and 0.04 gm of citric acid. The temperature is increased to 90°C and the mixing was continued for 60 minutes. Then 6 gm of clay is added with stirring and maintained at 90°C for 90 minutes. The reaction mixture is filtered and again the

clay treatment was performed twice with 6 gm of clay in each step. The metals content of raw jatropha carcass oil and treated oil is given below in Table-8.

Example-9
[031] 200 gm jatropha carcass oil containing 413 ppm ff metals was heated up to 50°C
followed by mixing 0.10 gm phosphoric acid and 0.04 gm of citric acid. The temperature is
increased to 90°C and the mixing was continued for 60 minutes. Then recycled clay separated
from second stage of previous experiment was added with stirring and maintained at 90°C for 90
minutes. The reaction mixture is filtered and again treated with recycled clay separated from
third stage of previous experimen.. The filtered product was treated with 6 gm of fresh clay.
[032] The metal content after treatment is given below in Table-9. It is evident from
these examples that use of fresh clay has been minimized by one third by recycling of clay in counter current manner


Example-10
[033] 200 gm jatropha carcass oil containing 413 ppm of metals was heated up to 50°C
followed by mixing 0.10 gm phosphoric acid and 0.04 gm of citric acid. The temperature is
increased to 90°C and the mixing was continued for 60 minutes. Then recycled clay separated
from second stage of previous experiment was added with stirring and maintained at 90°C for 90
minutes. The reaction mixture is filtered and again treated with recycled clay separated from
third stage of previous experimen.. The filtered product was treated with 6 gm offresh clay.
[034] The treated oil from third stage of clay treatment is sent to ion exchange resin to
reduce metal below 1 ppm. The metal content after treatment is of is given below in Table-10.


[35] Having described the invention in detail with particular reference to the
illustrative examples given above and the accompanying drawings, it will now be more specifically defined by means of claims appended hereafter.

WE CLAIM:
1. An environment friendly process for removal of total metals below 1 ppm in
vegetable oils/animal oils/fats by treating with clay in one or more stages,
characterized in that an inorganic acid and an organic acid are simultaneoully applied so that their synergistic effect enhances the performance and reduces the requirement of the said acids, in that the process is conducted without involvement of water washing step making the process effluent free and in that it reduces the consumpiion of clay.
2. The process as claimed in claim 1, comprises one or more than one stages of clay treatment with 0.5 to 5.0% clay of oil at 80-100°C for 30-90 minutes under stirring after acid mIxing.
3. The process as claimed in claim 1; wherein the inorganic acid is phosphoric acid and the organic acid is citric acid.
4. The process as claimed in claim 1, wherein phosphoric acid alone is used and its proportion ranges from 0.01 to 0.10 wt%, preferably 0.02 to 0.08 wt% and more preferably 0.03 to 0.05 wt% with respect to the oils/fats used. --^P"-
5. The process as claimed in claim 1, wherein citric acid alone is used and its proportion ranges from 0.01 to 0.10 wt%, preferably 0.02 to 0.08 wt% and more preferably 0.02 to 0.04 wt% with respect the oils/fats used.
6. The process as claimed in claim 1, wHerein both phosphoric as well as citric acid are used simultaneoully and their proportions range from 0.01 to 0.10wt% each with respect to the oils/fats used.

7. The process as claimed in claim 1, which is carried out at a temperature of 40-100°C under constant agitation.
8. The process as claimed in claim 1, wherein the proportion of clay used ranges from 0.5 to 5 wt% with respect to the oils/fats used at a temperature range of801000°C.
9. The process as claimed in claim 1, wherein the clay is used in multiple stages with fresh clay and/or recycled clay.
10. The process as claimed in claim 1, wherein the treatment with clay is carried out in counter-current movemen..
11. The process as claimed in claim 9, wherein the fresh clay is added in the last stage oftreatment.
12. The process as claimed in claim 9, wherein the fresh clay may be added in all stages oftreatment and spent clay may be withdrawn from each stage.
13. The process as claimed in claim 9, wherein recycled clay is separated by employing hydrocyclone separator.
14. The process as claimed in claim 1, wherein spent clay is separated by employing filter press.
15. A process for removal of contaminant metals from oils/fats comprising treating the oils/fats with phosphoric acid and/or citric acid followed by clay in one or more stages and finally with ion exchange resin to bring down the metal content even below 1 ppm.
16. The process as claimed in claim 15, wherein the ion exchange resin is selected from one or more matrix of styrene, cross linked polystyrene, cross linked polyacrylic, cross linked polymethacrylic resin or the like.

17. The process as claimed in claim 15, wherein the ion exchange resin is selected from the commercially available resins in the form of gel, macroporous or isoporous or the like.
18. The process as claimed in claim 15, wherein ion exchange treatment is carried out using two or more than two beds of ion exchange resin being operated in swing mode of demetallation and regeneration.
19. The process as claimed in claim 15, where regeneration of ion exchange resin is carried out by circulation of an alcohol like isopropyl alcohol and dilute solution of an inorganic acid like HCI.
20. The process as claimed in claims 1 and 15, wherein oils/fats used are vegetable oils/animal oils/fats.
21. The process as claimed in claim 20, wherein vegetable oil is selected from one or more of jatropha carcass oil, karanj oil, caster oil; ricebran oil, soybean oil, sunflower oil; palm oil, rapeseed oil etc and animal oil/fat is seleCted from one or more of fish oil, lard or the like.
22. The process as claimed in claims 1 and 15,wherein the metal contaminants include P, Na, K, Ca, Mg, Cu, ZN, Mn and Fe or anyother metal contaminant.