WO2023187628A2

WO2023187628A2 - Process for removing organic chlorine from used cooking oils (uco), animal and vegetable recovery fats (avr), and pyrolysis oils (po) derived from waste

Info

Publication number: WO2023187628A2
Application number: PCT/IB2023/053051
Authority: WO
Inventors: Andrea BERNARDINI; Franco Cataldo; Daniele Mora
Original assignee: Technoilogy S.R.L.
Priority date: 2022-03-31
Filing date: 2023-03-28
Publication date: 2023-10-05
Also published as: IT202200006428A1; WO2023187628A3

Abstract

Process for reducing the organic chlorine content in oils and fats of the UCO, AVR and PO classes by means of heat elimination reactions with a reagent selected from : alkali metal carbonates and alkali-earth metal carbonates; alkali metal alcoholates and alkali-earth metal alcoholates; finely divided elementary metals of the third and fourth period of the Periodic Table of Elements; and mixtures thereof. The reaction products are then mixed with wash water added with citric or formic acid, to favour the trans fer of said inorganic salts from the oily phase to the aqueous phase. Finally, such mixture is centrifuged to separate a ready-to-use oily phase with reduced content of organic chlorine, and an aqueous phase containing in solution inorganic salts of chlorine, for further purification.

Description

PROCESS FOR REMOVING ORGANIC CHLORINE FROM USED COOKING OILS (UCO) , ANIMAL AND VEGETABLE RECOVERY FATS (AVR) , AND PYROLYSIS OILS (PO ) DERIVED FROM WASTE

DESCRIPTION

FIELD OF THE INVENTION

The present invention refers to a process for removing organic chlorine from residual used cooking oils (UCO ) , animal and vegetable recovery fats (AVR) and pyrolysis oils (PO) generally derived from vegetable biomasses , or pyrolysis oils from organic waste in general, including pyrolysis oils from plastics and rubbers at the end of use, either pure or mixed with pyrolysis oils of different origins . STATE OF THE PRIOR ART

Residual vegetable oils and animal fats from normal cooking processes ( such as frying) are used as feedstock for producing fuels following a concept of circular economy . Such feedstock is known by the acronym UCO (Used Cooked Oils ) and is mainly used to produce biodiesel, also called UCOMe (Used Cooked oils methyl esters ) , or HVO (Hydrogenated Vegetables Oils ) . This latter proces s involves UCO hydrogenation followed by an isomerization proces s of the resulting aliphatic product . Currently, more than 2 . 5 Mton of UCO are used in the EU+UK alone , of which just over 50% is imported from abroad [van Grinsven, A . _f van den Toorn, E. , van der Veen, R. , Kampman, B. , & Oil, C. (2020) . Used Cooking Oil (UCO) as biofuel feedstock in the EU] .

The main advantage in reusing UCOs is that CO2 emissions are reduced, as UCOs are plant-based products and therefore derived from renewable sources . On the other hand, UCOs have the drawbacks of being considerably variable in their chemical composition and origin and of presenting undesirably high levels of organic chlorine and sulphur, which give rise to combustion, when using UCOMe, resulting in the production of acid fumes containing HC1 and SO2, which are corrosive to engines and boilers and harmful to the environment . Another drawback of UCOs can sometimes be their high content of organic phosphor, which can interfere in the transesterification reactions used to transform UCOs into UCOMe . Furthermore , when UCOs are used as the feedstock to produce HVOs , it immediately becomes apparent how high Cl ( and also S and P ) content s can poison the very delicate catalyst s needed for the HVO process . Therefore , although UCOs having low Cl content ( and pos sibly limited contents of S and P as well ) are highly desirable , the current chemical technology has not yet of fered specifically developed and economically applicable chemical proces ses to mitigate the content of the elements mentioned above in UCOs .

Applying circular economy to the production of fuels also includes recovering animal fats of any origin and provenance, besides the UCOs just mentioned, such as for example animal fats of risk class 1 , 2 and 3 , and tallow, or by-product s derived from the processing of vegetable oils of any origin . As general nonlimiting examples we cite POME = (Palm Oil Mills Ef fluent s ) , olein mixtures such as by-products of vegetable oil refining in general, as well as SBEO = ( Spent bleaching Earths Oils ) . Such animal and vegetable recovery fats (hereinafter referred to with the acronym AVR) , can be used for the same final applications we mentioned above about UCO, i . e . , biodiesel production or HVO production . Obviously, AVRs pose exactly the same issues as UCOs and therefore pre-treatment s such as to mitigate their chlorine ( and preferably also the sulphur and phosphor) content would also be desirable for them; however, the current chemical technology has not yet offered specifically developed and economically applicable chemical processes to reduce the Cl content , and preferably also limit the content s of S and P , in AVRs .

In parallel with UCOs and AVRs , POs (pyrolysis oils ) , which can be derived from vegetable biomas s pyrolysis , as well as from pyrolysis of various solid waste, are another feedstock falling within the scope of circular economy concept . Thus , POs are quite a broad class of product s , ranging pyrolysis products from wood and related materials to pyrolysis from generic biomasses and even algae . However, POs also include certain oils resulting from pyrolysis of rather generic waste such as , for example, RDFs (Refuse Derived Fuels ) and SRFs ( Solid Recovered Fuels ) , which also contain pyrolysis products of waste plastics and rubbers . POs exclusively derived from pyrolysis of plastics and/or rubbers do also exist . The chlorine content and the need to minimize it are of primary importance also in the case of POs , for the same reasons explained above regarding UCOs and AVRs . However, specifically developed and economically applicable chemical proces ses for the mitigation of the chlorine and sulphur content s in POs have not yet been of fered in the state of the art .

TECHNICAL PROBLEM

The technical problem addressed by the present invention is therefore that of bridging the gap of the prior art regarding chemical proces ses apt to achieve a chlorine content reduction in oils and fats used in the circular economy, in order to eliminate the drawbacks described above which strongly penalize the reuse of such waste product s as feedstock, taking particularly into account that these waste product composition is highly variable for each single processed batch and cannot be predicted a priori .

In the context of this technical problem, a first object of the present invention is therefore to of fer a chemical process for removing or at least strongly reducing the organic chlorine content in product s belonging to the UCO, AVR and PO classes .

Given the wide intrinsic variability of products falling within such classes , a second ob ject of the present invention is then to offer a particularly versatile chemical proces s , i . e . , a process which allows to achieve significant reductions in the chlorine content of said product s , regardles s of the chemical nature of the product treated from time to time .

Furthermore, a third ob ject of the present invention is to offer a chemical process which also has an additional ef fect of limiting the sulphur and phosphor contents in products belonging to the UCO, AVR and PO clas ses , in addition to strongly reducing the chlorine content .

Finally, a fourth ob ject of the present invention is to offer a chemical proces s as indicated above, based on the use of easy to find and low-cost reagents which are not dangerous to handle . SUMMARY OF THE INVENTION The above highlighted technical problem is solved, and the obj ects of the invention achieved, by means of a proces s for removing organic chlorine and limiting sulphur and phosphor contents in products belonging to the UCO, AVR and PO clas ses , having the features defined in the independent claims 1 , 4 and 8 . Other preferred features of such proces s are defined in the secondary claims .

In particular, reagents to be used in said process form the sub ject of the present patent application, which reagent s are apt to promote organic chlorine elimination reactions so as to remove and/or strongly limit the organic chlorine content and to have beneficial ef fect s in reducing sulphur and phosphor content s as well in product s belonging to the UCO, AVR and PO classes by means of an acces sible and economical chemical process . Such reagent s consist of some specific reagents in the form of metal or elementary metal salt s , apt to form inorganic salt s with chlorine , sulphur, and phosphor through elimination reactions . These reagent s are selected from : alkali metal and alkali-earth metal carbonates ; alkali metal alcoholates and alkali-earth metal alcoholates ; metals of the third and fourth period of the Periodic Table of Elements , in finely divided metallic form; and mixtures thereof . BRIEF DESCRIPTION OF THE EXAMPLES AND DRAWINGS

Further features and advantages of the process for removing organic chlorine according to the present invention will in any case become more evident from the following non-limiting Examples of chlorine, phosphor and sulphur elimination reactions in various product s belonging to the UCO, AVR and PO clas ses , as well as from the following detailed description of a preferred embodiment of said proces s , provided purely by way of non-limiting example , and illustrated in the attached drawings , wherein :

Fig . 1 is a diagram of a first portion of a plant wherein a first stage of the process of the present invention is carried out , which provides for the reaction of elimination of organic chlorine as inorganic chlorides ;

Fig . 2 is a diagram of an additional portion of a plant for vacuum creation, condensation of low boiling fractions and inertization through nitrogen; and

Fig. 3 is a diagram of a second portion of a plant wherein a second stage of the process of the present invention is carried out, which provides for the washing, solubilization and removal of the inorganic chlorides, with separation of the reaction products into a purified and subsequently dried oily phase, an aqueous phase to be treated and an oily phase to be recycled.

For ease of description, reference will be mainly made in the following to the process of elimination of organic chlorine in the form of inorganic chlorine salts, but it should be understood that this definition shall also include the simultaneous elimination or reduction of organic sulphur and phosphor as inorganic metal salts thereof.

EXAMPLES 1-13 - UCO DECHLORINATION PROCESS

A wide variety of UCOs is available on the market. Aiming to show the wide effectiveness of the dechlorination process described herewith, the reagents of the invention were tested on five different UCOs having different chemical composition, thermal history, and origin. Being complex mixtures, the selected UCOs were characterized by Fourier transform infrared (FT-IR) spectroscopy .

UCO "A": characterized by infrared spectrum as follows (absorption bands in cm^-11 : 3008 (w) ; 2954 (sh) ; 2924 (vs) ; 2853 (s) ; 1745 (s) ; 1465 (ms) ; 1457 (ms) ; 1417 (mw) ; 1377 (m) ; 1278 (w) ; 1238 (m) ; 1162 (s) ; 1118 (m) ; 1099 (m) ; 722 (m) . The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 1.

UCO "B": characterized by infrared spectrum as follows (absorption bands in cm^-1) : 3009 (w) ; 2925 (vs) ; 2855 (s) ; 1742 (vs) ; 1463 (m) ; 1436 (m) ; 1361 (w) ; 1245 (m) ; 1196 (ms) ; 1171 (s) ; 1119 (w) ; 1019 (w) ; 722 (m) . The Cl, P and S contents determined by XRF are shown in Table 1.

UCO "C": characterized by infrared spectrum as follows (absorption bands in cm^-1) : 3008 (w) ; 2955 (sh) ; 2923 (vs) ; 2851 (s) ; 1745 (vs) ; 1710 (sh) ; 1465 (m) ; 1437 (sh) ; 1416 (mw) ; 1377 (m) ; 1267 (sh, w) ; 1239 (mw) ; 1165 (m) ; 1117 (mw) ; 1100 (mw) ; 1059 (w) ; 723 (m) . The Cl, P and S contents determined by XRF are shown in Table 1.

UCO "D": has an infrared spectrum quite similar to UCO "B" although the Cl, P and S contents determined by XRF are different from those determined on UCO "B" as shown in Table 1.

UCO "E": has an infrared spectrum quite similar to UCO "B" although the Cl, P and S contents determined by XRF are different from those determined on UCO "B" as shown in Table 1. EXAMPLES 1-9

Each UCO oil of Table 1 (100 g) was treated with a 1:1 mixture by weight of Na2COs and K2CO3 according to the percentage amount against the UCO mass indicated in Table 1, in a flat- bottomed flask with reflux condenser and magnetic stirrer. Moisture was excluded by mounting a CaC12 anhydrous valve on top of the reflux condenser. The temperature and heat-treatment time for each Example are reported in Table 1, under stirring at 400 rpm. At the end of the treatment, the still hot reaction mixture (about 100°C) is poured into 400 ml of double distilled water (DDW) and stirred at 1000 rpm. A partial emulsion is formed which is broken by careful addition of 6 ml of concentrated formic acid. Stirring is continued (650 rpm) while maintaining a temperature of 95°C. Afterwards, the mixture is transferred into a separating funnel and after a suitable rest time the underlying aqueous phase is discarded. The oil mass is washed again with hot DDW (250 ml) and, after a rest time, separated again with the aid of a separating funnel. The treated oil is then analysed by XRF and FT-IR (results are reported in Table 1) .

EXAMPLES 10 and 11

We proceeded as in the Examples 1-9 replacing the carbonates respectively with sodium methoxide (Example 10, Tab.l) or sodium ethoxide (Example 11, Tab.l) . Every other aspect of the process is identical to that described for the Examples 1-9. XRF and FT- IR analytical results are reported in Table 1. EXAMPLES 12 and 13

The UCO oil indicated in Table 1 (100 g) was added with Zn powder having particle size lower than 10 micrometres, according to the percentage amount against the UCO mass indicated in Table 1 . The reaction mixture was heated in a flat-bottomed flask with reflux condenser and magnetic stirrer . Moisture was excluded by mounting a CaC12 anhydrous valve on top of the reflux condenser .

5 Before starting to heat for activating the zinc powder surface, the reaction mixture was further added with 1-2 ml of concentrated formic acid (HCOOH ) . A weak hydrogen production was noticed . The temperature and heat-treatment time for each Example are reported in Table 1 , under stirring at 620 rpm .

10 After cooling and complete sedimentation of the zinc powder,

UCO was decanted, filtered on Whatmann paper, hot washed with 400 ml of double distilled water, trans ferred into a separating funnel , and the separated oily phase was subj ected ( after suitable separation of the two oil/water phases ) to XRF and FT-IR analysis

15 ( result s are reported in Table 1 ) .

COMMENTS ON EXAMPLES 1-13

From the data in Table 1 it can be seen that a first class 5 of reagents of the present invention consisting of an alkali carbonate mixture (in a ratio of 1:1 by weight of sodium carbonate and potassium carbonate, in the preferred embodiment of the invention) is effective for drastically reducing the chlorine content of UCO "A" from 21.6 ppm to only 2.0 ppm and of UCO "B" from initial 27 . 8 ppm to final 1 . 1 ppm of chlorine . As an additional effect , a drastic reduction or even a complete elimination of phosphor is also obtained, for example in UCO "B" from initial 109 ppm to zero ppm . Sulphur also undergoes a drastic reduction in both UCO "A" and UCO "B" . Same comment s also apply to other UCOs , for example "D" and "E" which have a different chemical composition and origin than UCOs "A" and "B" , but even in these ones the reagent consisting of the mixture of carbonates is always effective , mainly for removing chlorine but also for reducing phosphor and sulphur contents .

Infrared spectra (FT-IR) show that all the UCOs discus sed so far are characterized by low free acidity, as evidenced by a single infrared band at 1745 cm^-1 due to the ketone group of triglycerides . Treatment with carbonates does not alter the composition of such triglycerides , the infrared spectrum and the band at 1745 cm^-1 remaining unchanged after treatment .

A more dif ficult sample to be treat was the UCO "C" sample, which has the infrared band of glycerides at 1745 cm^-1 accompanied by an infrared band at 1710 cm^-1 due to free carboxyl groups . Therefore , UCO "C" also has a moderate free acidity from its origin . Examples 4-7 show that depending on the carbonate treatment temperature, UCO "C" shows an increase in the free carboxyl groups ( formation of mono and diglycerides from prevalent triglycerides ) . However, with a careful choice of the treatment temperature it is pos sible to limit this phenomenon of free acidity increase . On the other hand, the carbonate mixture ef fectivenes s in chlorine removal in UCO "C" is undisputed, especially at the highest used temperatures . UCO "C" turns out to be a dif ficult sample, as carbonates show limited effectiveness in mitigating the phosphor and sulphur content .

However, Examples 10 and 11 suggest that a clas s of alkali alcoholate-based reagent s - also ob ject of the present invention - as especially strong bases like sodium methoxide (CHsONa) or sodium ethoxide ( CHsC^ONa) , is particularly effective on difficult samples such as UCO "C" . The alkali alcoholate-based reagent s not only manage to reduce the chlorine content as desired, but also are very effective for mitigating the phosphor and sulphur contents, albeit with an increase in the final free acidity, as suggested by the intensity increase of the infrared band at 1710 cm^-1, indicating mono and diglyceride formation from an initial prevalent composition of triglycerides. The alkali alcoholates are preferably used in a mixture with alcohols, such as preferably methyl alcohol, ethyl alcohol and tert-butyl alcohol.

Examples 12 and 13 show instead the effectiveness of a further class of metal-based reagents in finely divided form, used likewise as dechlorinating agent and comprised within the object of the present invention; in particular, metallic zinc powder is used in these Examples. As a matter of fact, metallic zinc in finely divided form, especially if used at a sufficiently high temperature (Example 13) , shows not only an excellent dechlorinating action on the UCO "C", but also a moderate mitigating effect on the phosphor and sulphur contents of said UCO. Using a reagent based on metallic zinc powder offers the great advantage of not altering in any way the triglyceride content of the UCO and, consequently, of not leading to the formation of mono- and diglycerides .

Therefore, the object of the present invention comprises three classes of "reagents", i.e., chemical agents apt to drastically reduce the chlorine content and mitigate the phosphor and sulphur contents in UCOs of various origins and compositions (as a matter of fact, five UCOs of different origins and compositions were used in the above Examples) . The first class of reagents with dechlorinating effect on UCOs, object of the present invention, consists of alkali metal and alkali-earth metal carbonates (i.e., from Groups 1 and 2 of the Periodic Table of Elements) and mixtures thereof. The second class of dechlorinating agents effective on UCOs and object of the present invention consists of the wide range of alkali metal and alkali-earth metal alcoholates, from which sodium methoxide and ethoxide, potassium methoxide and ethoxide, and potassium t-butoxide are preferably used, due to costs and industrial accessibility. The third class of reagents with dechlorinating effect on UCOs and object of the present invention consist s of the metals of period 3 of the Periodic Table of Elements , preferably magnesium and aluminium, and period 4 of the Periodic Table of Element s , preferably iron, cobalt , nickel , copper, and zinc, all in finely divided metallic form, preferably 5 with particle size lower than 100 micrometres . In particular, from all the aforementioned metals , zinc is the metal showing the highest efficacy and the best industrial applicability .

EXAMPLES 14-17- ANIMAL AND VEGETABLE RECOVERY FATS (AVR) DECHLORINATION PROCESS

AVR recovery fat s are by nature rather variable in their general chemical composition, including the content s of the three element s of interest here , namely Cl, S and P . Such variability depends on the raw materials from which they derive , the pos sible mixing of said raw materials , and the fact that in any case they are waste fat s and therefore inedible but intended for other uses . The proces ses obj ect of the present invention, already described in Examples 1-13 of Table 1 , were identically applied to two AVR fat s , one of which is animal-derived (Examples 14 and 16 in Table 2 ) and the other vegetable-derived (Examples 15 and 17 of Table 2 ) .

COMMENTS ON EXAMPLES 14-17

From Examples 14-17 of Table 2 it can be seen that both the treatment with carbonate and with zinc powder were ef fective in reducing the chlorine content of the initial AVRs , regardles s of whether these fat s were of animal or vegetable origin . In addition to reducing the chlorine content , it was also pos sible , in the same treatment , to succes sfully mitigate the phosphor and sulphur content , as indeed discus sed and detailed in the case of UCOs .

Therefore, the classes of "reagent s" shown as ef fective dechlorinating agents and effective sulphur and phosphor contents mitigating agents for UCOs are also effective for AVRs . EXAMPLES 18-30 PO DECHLORINATION PROCESS

A wide variety of POs is available on the market . Aiming to show the wide ef fectiveness of the dechlorination process described herein, the reagents of the invention were tested on six dif ferent POs having different chemical composition, thermal history, and origin . Being complex mixtures , the selected POs were characterized by Fourier transform infrared (FT-IR) spectroscopy . PO "F" : characterized by infrared spectrum as follows (absorption bands in cm^-1) : 3349 (m) ; 3008 (mw) ; 2925 (vs) ; 2852 (s) ; 1636 (sh) ; 1613 (sh) ; 1596 (sh) ; 1588 (s) ; 1485 (m) ; 1457 (s) ; 1395 (w) ; 1346 (mw) ; 1265 (mw, br) ; 1155 (s) ; 1076 (w) ; 994 (m) ; 942 (w) ; 912 (m) ; 875 (w) ; 841 (w) ; 779 (m) ; 749 (w) ; 720 (m) ; 649 (ms) . Based on the infrared spectrum, it can be stated that PO "F" consists of a mixture of predominantly aromatic hydrocarbons. The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 3.

PO "G": characterized by infrared spectrum as follows (absorption bands in cm^-1) : 3079 (w) ; 3021 (sh) ; 2958 (vs) ; 2924 (vs) ; 2870 (s) ; 2842 (sh) ; 1738 (w) ; 1700 (w) ; 1642 (mw) ; 1596 (w) ; 1515 (m) ; 1451 (ms) ; 1457 (s) ; 1382 (m) ; 1366 (m) ; 1246 (mw) ; 914 (mw) ; 876 (ms) ; 814 (ms) . Based on the infrared spectrum, it can be stated that PO "G" consists of a mixture of predominantly aliphatic and cycloaliphatic hydrocarbons. The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 3.

PO "H": characterized by infrared spectrum as follows (absorption bands in cm^-1) : 3074 (w) ; 3059 (w) ; 3027 (w) ; 2957 (s) ; 2925 (vs) ; 2870 (s) ; 2854 (s) ; 1705 (w, br) ; 1648, 1639, 1631 (mw) ; 1603 (w) ; 1494 (m) ; 1453 (ms) ; 1414 (w) ; 1377 (m) ; 1081 (w) ; 1028 (w) ; 991 (m) ; 964 (w) ; 907 (w) ; 889 (m) ; 775 (s) ; 745 (mw) ; 729 (m) ; 697 (s) . Based on the infrared spectrum, it can be stated that PO "H" consists of a mixture of essentially aromatic hydrocarbons. At least formally, PO "H" appears to have been produced by RDF pyrolysis. The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 3.

PO "I": characterized by infrared spectrum as follows (absorption bands in cm^-1) : identical to PO "H" with the addition of one infrared band at 729 (ms) and one infrared band at 678 (m) . Based on the infrared spectrum, it can be stated that PO "I" consists of a mixture of essentially aromatic hydrocarbons. At least formally, PO "I" appears to have been produced by certain RDF pyrolysis. The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 3.

PO "J characterized by infrared spectrum as follows (absorption bands in cm^-1) : 3074 (vw) ; 3000 (vw, sh) ; 2958 (vs) ; 2926 (vs) ; 2870 (vs) ; 2835 (sh) ; 1705 (w, br) ; 1646 (w) ; 1513 (mw) ; 1447 (ms) ; 1376 (m) ; 1155 (w) ; 913 (w) ; 886 (m) ; 814 (mw) ; 786 (mw) . Based on the infrared spectrum, it can be stated that PO "J" consists of a mixture of predominantly naphthenic and aliphatic hydrocarbons. The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 3.

PO "K" : characterized by infrared spectrum as follows (absorption bands in cm^-1) : 2955 (m) ; 2924 (vs) ; 2854 (s) ; 1640 (vw) ; 1463 (m) ; 1376 (mw) ; 992 e 966 (vw) ; 908 (w) ; 888 (w) ; 720 (w, br) . Based on the infrared spectrum, it can be stated that PO "K" consists of a mixture of essentially aliphatic hydrocarbons. The chlorine, phosphor and sulphur contents were determined by X-ray fluorescence (XRF) and is reported in Table 3. EXAMPLES 18, 19, 23, 26, 27, 30

As indicated in Table 3, each PO of the above Examples (100 g) was treated with a 1:1 mixture by weight of Na2COs and K2CO3 according to the percentage amount against the PO mass indicated in Table 3, in a flat-bottomed flask with reflux condenser and magnetic stirrer. Moisture was excluded by mounting a CaC12 anhydrous valve on top of the reflux condenser. The temperature and heat-treatment time for each Example are reported in Table 3, under stirring at 400 rpm. At the end of the treatment, the still hot reaction mixture (about 100°C) is poured into 400 ml of double distilled water (DDW) stirred at 1000 rpm. Usually, no emulsion is formed with POs but, if an emulsion were occasionally to be formed, it would be broken by careful addition of 3 ml of concentrated formic acid. Afterwards, the mixture is transferred into a separating funnel and after a suitable rest time the underlying aqueous phase is discarded. The PO is washed again with hot DDW (250 ml) and separated again with the aid of a separating funnel after a rest time. The treated PO is then analysed by XRF and FT-

IR (results are reported in Table 3) .

EXAMPLES 20, 22, 25, 29

We proceeded as in the Examples 18, 19, 23, 26, 27, 30, by 5 replacing the carbonates respectively with sodium methoxide (Example 20, Tab.3) or potassium t-butoxide (Examples 22, 25, 29, Tab.3) . Every other aspect of the process is identical to the one described for the Examples 18, 19, 23, 26, 27, 30. XRF and FT-IR analytical results are reported in Table 3.

10 EXAMPLES 21, 24 and 28

As indicated in Table 3, each PO of the above Examples (100 g) was added with Zn powder having a particle size lower than 10 microns, in the percentage amount against the PO mass indicated in Table 3. The reaction mixture was heated in a flat-bottomed 15 flask with reflux condenser and magnetic stirrer. Moisture was excluded by mounting a CaC12 anhydrous valve on top of the reflux condenser. Before starting to heat, the reaction mixture was further added with 1-2 ml of concentrated formic acid (HCOOH) for activating the zinc powder surface. A weak hydrogen production 20 was noticed. The temperature and heat-treatment time for each Example are reported in Table 3, under stirring at 620 rpm.

After cooling and complete sedimentation of the zinc powder, PO was decanted, filtered on Whatmann paper, hot washed with 400 ml of double distilled water, transferred into a separating fun- 25 nel, and after discarding the aqueous phase the recovered PO phase was subjected (after suitable separation of the two oil/water phases) to XRF and FT-IR analysis (results are reported in Table 3) .

COMMENTS ON EXAMPLES 18-30

Since POs essentially consist of complex mixtures of hydrocarbons, they do not present the risk of hydrolysis of glycerides 5 like UCOs do; Table 3 shows, in fact, that the dechlorination treatments do not alter the infrared spectra of all the tested POs. Accordingly, all the treated POs show the same infrared spectrum of the starting POs.

When subjected to the action of a mixture of sodium and 10 potassium carbonates (see Examples 18, 23, 26, 27, 30 in Table 3) some POs, such as "F", "H", "I", "J" and "K", respond very well to the dechlorinating effect further accompanied by a desirable reduction of the phosphor and sulphur contents of the POs. However, there are also POs which are completely recalcitrant to the 15 carbonate mixture action. This is the case of PO "G" of Example 19 in Table 3, where the carbonates are completely ineffective in the substrate dechlorination reaction.

Similar difficult cases can be worked out by using alcoholates as illustrated in Example 20 where PO "G" was successfully 20 treated with sodium methoxide, leading to a reduction of the chlorine content from initial 613 ppm to final 445 ppm. Another alcoholate used on PO "G" is potassium t-butoxide (Example 22, Table 3) with a dechlorination from initial 613 ppm to final 288 ppm, and beneficial effects also on the sulphur content from initial 19.9 ppm to final 2,8. Of course, alcoholates are also effective on substrates which are "easier" to be treated, such as PO "H" and PO "J", as respectively illustrated by Examples 25 and 29 of Table 3.

Finally, finely divided zinc also proved to be highly effective for dechlorinating difficult substrates such as PO "G". As a matter of fact, Example 21 in Table 3 clearly shows that zinc powder is apt to reduce the chlorine content of PO "G" from initial 613 ppm to only 147 ppm, as well as the sulphur content from 19.9 ppm to 1.3 ppm. Obviously, as in the case of alcoholates, zinc powder is an effective dechlorinating agent also with "normal" PO substrates, as for example in the case of PO "H" and PO "J" whose respective data are reported in Example 24 and in Example 28.

Therefore, the three classes of "reagents" shown as effective dechlorinating agents and effective sulphur and phosphor mitigating agents for UCOs and AVRs are also effective for POs. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE DECHLORINATION PROCESS

According to the present invention, the organic chlorine removing process involves a first stage wherein products of the UCO, AVR or PO classes are treated with the various classes of reagents mentioned above to reduce the chlorine content, and preferably also the sulphur and phosphor contents, in the organic substrate .

The aforementioned reagents are added, individually or mixed as desired, directly (in a solid powdery state) to the mass to be treated (only in the case of alcoholates, concentrated solutions in alcohol can be used as an alternative to the powder reagent, e.g., sodium methoxide in methanol, sodium ethoxide in anhydrous ethyl alcohol and potassium t-butoxide in tert-butanol) . The reagents are then carefully mixed with the charge of UCO, AVR or PO in a proportion of 0.01-10% by weight and allowed to react at temperatures between 50° and 220°C, preferably between 100° and 200 °C, for a period ranging from 1 to 12 hours , depending on the chlorine content in the feedstock to be removed .

During the reaction period, organic chlorine elimination reactions occur wherein chlorine combines in whole or in part with metals contained in the reagents to form inorganic chlorides which are then easily removed by subsequent washing with water wherein said inorganic chlorides are completely soluble , followed by separation of the resulting aqueous solution . The following reactions illustrate some of the elimination reactions occurring in the treated substrates (UCO, AVR, PO) (wherein R and R ' are two generic alkyl or aryl radicals ) :

R-CH (Cl ) -CH ( Cl ) -R' + Zn - R-CH=CH-R' + ZnCl₂

A preferred plant for carrying out the dechlorination reaction described above is illustrated in the accompanying drawings . With reference to Fig . 1 , the charge A of UCO, AVR and PO to be sub jected to dechlorination is fed to tank 1 together with a flow B coming from the second part of the plant , then filtered in filter 2 to eliminate suspended solids , preheated in the heat exchanger 3 , and brought to the process temperature in the heat exchanger 4 which is fed by the same charge coming out from the reaction zone .

The thus preheated charge is mixed in the mixer 6 or in the reactor 7 with the reagents from the tanks 5 , and pos sibly with formic acid from the tank 5b and/or citric acid from the tank 5c . Such charge added with the reagent solution is then sent to one or more reactors 8 arranged in series . In the drawing four reactors 8 are shown, nonetheless it should be clear that the number and size of the reactors 8 are calculated as a function of the charge flow rate and the chlorine concentration in the incoming charge A, to have an overall contact time of such charge with the reagent s suf ficient to obtain the desired reduction of said concentration . The reaction occurs , as mentioned above, within a defined range of temperatures guaranteed by a heating system through heat exchangers 9 . For the overall proces s to have an adequate yield, the fatty acids , which at the operating conditions could evaporate or be entrained by the gases produced by the reaction, are suitably condensed and recycled inside the reactors themselves , through reflux condensing systems 10 . Where neces sary, and as better specified below, the non condensable gases substantially consisting of carbon dioxide , as a by-product of the chlorine elimination reactions , and of any other low boiling polluting components in traces , are removed by means of one or more e jectors 12 (or vacuum pumps ) which maintain the desired degree of vacuum in the system .

In case, due to the charge volatility, the reaction is carried out in atmospheric conditions or at autogenous pressure , a system of condensation of low boiling fractions ( 14 ) and inertization through nitrogen ( 15 ) is provided .

The flow leaving the last of the reactors 8 is further homogenized in the mixer 11 , cooled in the heat exchanger 4 apt to preheat the incoming charge A as already seen above , and finally further cooled in the heat exchanger 13 until a flow D is obtained having a suitable temperature for the subsequent stage of separation of inorganic chlorides (Fig . 2 ) which are the dechlorination reaction product .

In Fig . 2 a possible stage of separation of said inorganic chlorides is illustrated, wherein such separation is carried out by washing with water the UCOs , AVRs or POs leaving the reaction stage ( flow D ) . The treatment water contained in a tank 16 is added in mixers 17 with citric acid or formic acid from tank 5c and tank 5b, respectively, in such a ratio as to obtain a concentration of citric/f ormic acid in the treatment water comprised between 0 . 01% and 2 . 0% by weight . The thus obtained solution is then mixed in a mixer 18 with the flow of reaction product s D coming out from the reaction stage, in a flow rate ratio between 1% and 10% . The reaction products with added water and citric/ for- mic acid are then sent to a reactor 19 which allows a suitable contact time between the oily phase and the aqueous phase to allow the transfer of inorganic chlorides from the former to the latter . The citric acid or the formic acid in the aqueous phase precisely serves to make this phase trans fer faster and more complete .

Afterwards , the biphasic mixture leaving the reactor 19 head is sent to a centrifuge 20 from which an oily phase with reduced organic chlorine content and substantially no water, and an aqueous phase containing the inorganic chlorides and contaminated with oils come out . The oily phase can usefully be sent to a second separation stage , completely identical to the one described above , and therefore comprising a reactor 19 ' and a centrifuge 20 ' , upon mixing with a second flow of water and citric/f ormic acid in a second mixer 18 ' , while in both cases the aqueous phase contaminated with oils is sent to a single storage tank 21 .

In the tank 21 the aqueous and oily phases separate by decantation; the oily phase is then recycled as flow B to the first stage of the proces s to be further treated, while the aqueous phase containing the dis solved inorganic chlorides is sent as flow F to a per se well known treatment of purification by inorganic chloride separation .

The oily phase coming out from the second centrifuge 20 is instead directly sent to use - except for a pos sible fraction of recirculation, as flow C, sent to the mixer 11 - upon pos sible drying proces s which preferably takes place by stripping the residual free water eventually entrained in the oily phase ( flow E ) in a vacuum flash column 22 by means of connection to the same e jectors 12 ( or vacuum pumps ) , in a manner therefore per se well known . Finally, the flow G of dechlorinated UCOs , AVRs and POs is withdrawn from the base of the flash column 22 , ready for subsequent treatment s or use .

At the end of the dechlorination proces s described above, it was also possible to ascertain a significant reduction of the sulphur and phosphor content s in the reaction products , with respect to those of the initial product s belonging to the UCO, AVR and PO clas ses . COMMENTS ON THE PRESSURE OPERATING CONDITIONS OF DECHLORINATION PROCESSES

All the proces ses illustrated in Table 1 (Examples 1-13 , about UCO dechlorination ) , in Table 2 (Examples 14-17 , about AVR dechlorination) and in Table 3 (Examples 18-30 , about PO dechlorination) were conducted under atmospheric pres sure in the preferred embodiments of the present invention . However, for both UCOs and AVRs the same treatments described respectively in Examples 1-13 and 14-17 were also success fully carried out under vacuum .

In detail, the only dif ference is that the reactor was connected to a suitable vacuum pump, with a vacuum connection at the top of a reflux condenser . An additional coil cooled trap was placed between the reflux condenser and the vacuum pump to prevent any vapours of the reaction mixture from going into the vacuum pump . Vacuums down to 0 . 1 millibar were applied with no problems . Since both UCOs and AVRs are mixtures of glycerides and high boiling fatty acids ( in their ma jor fraction ) , they do not distil at 200-220 °C with a 0 . 1 millibar vacuum . The advantage offered by high vacuum concerns the certain volatilization of any polluting component s present in traces in the UCOs and AVRs under treatment , as well as a protection from UCO and AVR oxidation which is inevitable when working under atmospheric pressure and in the presence of air . Finally, when alkali metal and alkali-earth metal carbonates are used as dechlorination "reagents", the CO2 released by the high-temperature elimination reaction is immediately removed by the applied vacuum . For these reasons , the preferred embodiment of the dechlorination proces s of the invention is , in fact , under vacuum .

In the case of PO dechlorination, the application of vacuum can show the same advantages listed above for the UCO and AVR vacuum treatment . However, many POs have large distillation curves with low boiling fractions . Therefore , the application of vacuum in the treatment of POs cannot always be practiced and must therefore be evaluated on a case-by-case basis , based on the relative distillation curve . To conclude, the present invention of UCO, AVR, and PO dechlorination by means of the three classes of "reagents" above, can be carried out either under atmospheric pressure, in the presence of air or inert gas such as nitrogen or carbon dioxide, or under vacuum, to any degree of vacuum but preferably in the range of 0.1 to 100 mbar.

From the foregoing description it becomes clear how the present invention has fully achieved all the intended objects, having identified a process for removing organic chlorine from products belonging to the UCO, AVR and PO classes, based on simple elimination reactions of organic chlorine as inorganic metal salt, by use of three different classes of easy to find, low cost, and low hazard reagents. The selection of the most suitable class of reagents for each single processing batch of products of the UCO, AVR and PO classes can be easily performed by means of preliminary laboratory tests on samples of the batch to be treated.

The present invention has been described in its preferred embodiments. It is understood that those skilled in the art will be able to make modifications and to apply process analogies without thereby departing from the relative scope of protection which is solely defined by the appended claims.

Claims

1 ) Process for reducing the organic chlorine content and pos sibly also the sulphur and phosphor contents in oils and fats of the UCO, AVR and PO clas ses , characterized in that it includes a first reaction stage wherein a flow of oils and fat s of the UCO, AVR and PO classes is heat treated with a reagent selected from alkali metal carbonates and alkali-earth metal carbonates , giving rise to elimination reactions wherein organic chlorine and possibly other heteroatoms of sulphur and phosphor contained in said flow of oils and fat s are transformed into their inorganic metal salts , and a second separation stage wherein the thus obtained inorganic metal salt s of chlorine, sulphur and phosphor are separated from said oils and fat s by washing with water .

2 ) Process for reducing the chlorine, sulphur and phosphor content s in oils and fat s of the UCO, AVR and PO classes as in claim 1 , wherein said reagent is selected from sodium carbonate , potas sium carbonate and mixtures thereof .

3 ) Process for reducing the chlorine, sulphur and phosphor content s in oils and fat s of the UCO, AVR and PO classes as in claim 2 , wherein said reagent consist of a 1 : 1 mixture by weight of sodium carbonate and potas sium carbonate .

4 ) Process for reducing the organic chlorine content and pos sibly also the sulphur and phosphor contents in oils and fats of the UCO, AVR and PO clas ses , characterized in that it includes a first reaction stage wherein a flow of oils and fat s of the UCO, AVR and PO classes is heat treated with a reagent selected from alkali metal alcoholates and alkali-earth metal alcoholates , giving rise to elimination reactions wherein organic chlorine and pos sibly other heteroatoms of sulphur and phosphor contained in said flow of oils and fats are transformed into their inorganic metal salts , and a second separation stage wherein the thus obtained inorganic metal salt s of chlorine , sulphur and phosphor are separated from said oils and fats by washing with water .

5 ) Process for reducing the chlorine, sulphur and phosphor content s in oils and fat s of the UCO, AVR and PO classes as in claim 4 , wherein said reagent is selected from sodium methoxide , potassium methoxide, sodium ethoxide, potassium ethoxide, potassium t-butoxide and mixtures thereof.

6) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 5, wherein said reagent is mixed with alcohols before introducing it into said flow of oils and fats of the UCO, AVR and PO classes.

7) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 6, wherein said alcohols are selected from methyl alcohol, ethyl alcohol and tert-butyl alcohol.

8) Process for reducing the organic chlorine content and possibly also the sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes, characterized in that it includes a first reaction stage wherein a flow of oils and fats of the UCO, AVR and PO classes is heat treated with a reagent selected from elementary metals of the third and fourth period of the Periodic Table of Elements in finely divided metallic form, and mixtures thereof, giving rise to elimination reactions wherein the organic chlorine and possibly other heteroatoms of sulphur and phosphor contained in said flow of oils and fats are transformed into their inorganic metal salts, and a second separation stage wherein the thus obtained inorganic metal salts of chlorine, sulphur and phosphor are separated from said oils and fats by washing with water.

9) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 8, wherein said reagent is selected from Mg and Al, as metals of the third period of the Periodic Table of Elements and from Fe, Co, Ni, Cu, Zn as metals of the fourth period of the Periodic Table of Elements, in finely divided metallic form, and mixtures thereof.

10) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 9, wherein said reagent is metallic zinc in finely divided form.

11) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claims 1, 4 and 8, wherein said reagents are used in a concentration by weight of 0.01-10%, with respect to the flow of oils and fats to be treated.

12) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claims 1, 4 and 8, wherein the temperature in said first reaction stage is maintained between 50° and 220°C, and preferably between 100° and 200°C.

13) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claims 1, 4 and 8, wherein the reaction time in said first reaction stage is between 1 and 12 hours.

14) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claims 1, 4 and 8, wherein the flow of oils from the first reaction stage is mixed in the second separation stage with wash water added with a separation adjuvant, in a ratio of 1-10%, to favour the transfer of said inorganic metal salts from the oily phase to the aqueous phase, and then this mixture is centrifuged to separate a ready-to-use oily phase with reduced contents of organic chlorine, sulphur and phosphor, and an aqueous phase contaminated with oils and containing in solution inorganic salts of chlorine, sulphur and phosphor, for further purification.

15) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 14, wherein said separation adjuvant is selected from citric acid and formic acid in concentrations comprised between 0.01% and 2% by weight with respect to the wash water.

16) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 14, wherein a decanting stage is also provided for said aqueous phase contaminated with oils and containing in solution said inorganic metal salts, to separate a residual oily phase, which is recycled to the first reaction stage, and an aqueous phase containing in solution said inorganic metal salts, which is sent to a purification treatment by separation of said inorganic metal salts.

17) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claims 1, 4 and 8, wherein the first reaction stage is carried out under reflux.

18) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 17, wherein both the first reaction stage and the second separation stage are carried out under autogenous pressure with condensation of low boiling fractions (14) and inertization through nitrogen (15) .

19) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 17, wherein both the first reaction stage and the second separation stage are carried out under atmospheric pressure with condensation of low boiling fractions (14) and inertization through nitrogen (15) .

20) Process for reducing the chlorine, sulphur and phosphor contents in oils and fats of the UCO, AVR and PO classes as in claim 17, wherein both the first reaction stage and the second separation stage are carried out under vacuum.