DESCRIPTION

The present invention relates to a proces s for the production of lubricating biooils , starting from wastes of fat and surfactant substances . The process of the present invention can be fully included in the so-called circular economy .

Several industrial revolutions and scientific and technical discoveries derived therefrom have led to a remarkable well-being and to a strong improvement in the quality of life , in addition to considerably lengthening it . Today' s mean life exceeds by far 70 years and it occurs that old age, meant as a reduction of the pos sibility to perform normal physical activities , starts later and later, often after 80 years . However, for every positive aspect , there is always a downside . In the case of technical and scientific progres s , one of these downsides is certainly the production of any type of wastes , which have to be eliminated somehow . At first , this was made simply somehow discarding wastes in the environment , without any particular precaution . This has however led to remarkable damage , both in terms of contamination, creating real open-air dumps in more or less uninhabited places , and of progressive poisoning of groundwater layers , water streams and soil , with health problems connected to the crops obtained in these areas . Production of harmful gaseous substances was also pos sible .

As the problem occurred and revealed it self more serious , an attempt to cleanse the polluted areas was carried out , trying to take away harmful substances , pos sibly trans forming them into substances that could be eliminated without damage or anyway limiting damage as much as possible . However, these operations are very expensive, much more than preventing the creation of wastes or than removing them as soon as they are formed . It is apparent for the expert in the art that being able to collect wastes as soon as they are produced, without dispersing and mixing them with other substances makes every possible treatment much easier, using easier conversion reactions , avoiding all cost s of detection, collection, and transport of wastes in treatment places , and not risking of additional accidental and even unintended dispersions of wastes . Understanding this has led to the creation of compulsory consortiums , such as those for used oils , that take care of collecting waste substances directly from those that produce them . For example , a compulsory consortium for used edible oils receives all used fried oil from those who fry ( restaurant s , food industries and the like ) , which is no longer useful for cooking use due to the impurities that it contains and sometimes also to chemical composition modifications that can also make it dangerous for the health; the non-delivery of these wastes to the consortium may entail penalties for the negligent professional .

The subsequent step was to realise that waste substances are often rich in materials that , with few, sometimes not even particularly complicated, treatments can provide starting or semifinished materials , which can then be used to make product s having some market available, often with production cost s even lower than those normally to be faced starting from primary starting materials . In any case, instead of working and consuming energy in order to remove substances that are simply to be destroyed, the same energy and the same work are employed to get product s that can be sold, often ever easily . So, there are companies that get paid to collect waste that they then transform into product s , obtaining a second income from their selling, and that face only the conversion cost s , and not those of purchase of starting materials . Basically, the so-called circular economy consists in this , allowing to reuse wastes deriving from the use of certain product s to obtain other products .

In this definition, processes for the regeneration of used mineral oils , mainly lubricant s for engines of various kinds are included with full right s , which, starting from wastes collected by related compulsory consortiums , obtain starting materials for lubricant s , that are then sold to manufacturers of lubricants to produce end product lubricants , and bitumen, which is mainly used to asphalt roads , but that sometimes has also other uses , mainly in the field of inks . All these products are widely marketable and have a certain market , therefore these proces ses , in addition to allow to prevent the input of pollutant s in the environment or their storage in places where they can be stored or burnt (with the risk of toxic smokes generation ) , allow those who practice them to get a certain income, triggering then a virtuous circle .

One of the Applicants of the present application ( Itelyum Regeneration) has filed various patents on the regeneration of used oils , developing in time a cutting-edge technology, which can be included with full right s in the so-called circular economy . Among these patents , Italian application no . 102015000026832 is to be mentioned . Obj ect of the invention of that application is the regeneration of used oils with a flash distillation step, before which oils to be regenerated undergo a saponification step, preferably in the presence of a strong base, such as KOH, generally operating at a temperature of about 200 °C . This proces s is particularly suitable for the recovery of mineral oils contaminated by esters of fatty acids derived from biofuels (biodiesel ) or biooils (used as additives or mixed with lubricant oils due to a wrong collection management ) , reducing the number of stops due to clogging of the oven that feeds a subsequent column for fractioned distillation . Furthermore, such process allows to carry out other regeneration steps under milder conditions , allowing then further energy savings .

Esters produce considerable amount s of soap or surfactants , which still represent a fraction to be eliminated and do not allow to completely close the recycling cycle , leaving a fraction to be eliminated and that , in time, might gather up in the environment , with possible damage .

However, those listed above are not the only wastes of fatty nature that industry has to dispose of .

From US 4 018 805 a method for the production of fatty acids starting from soaps is known .

From WO 2021 /149 025 the employment of a completely recyclable catalyst for the esterification of fatty acids is known . Food industry, food services at all levels and even families often use vegetable oils , be it olive oil, seed oil or other, for various purposes , mainly to fry : for this activity considerable amounts of oil are required . By using olive oil or treated seed oil in order to make it resemble olive oil (that displays the best characteristics of chemical stability and health for use for frying) , several frying cycles with the same oil can be performed, but in any case, sooner or later there comes a moment when the oil smells bad, leaves a stale taste , absorbs foreign substances , perhaps even harmful for the health, changes the chemical composition of some component s and therefore it has to be replaced . What is removed must then be disposed of . In the past , that type of oil was simply disposed of pouring it into the sewer (and in families often it still happens so ) . However, such an operation is to be avoided, since oil pollutes the groundwater layers . Furthermore, combining with other substances found in sewer, fats discharged are the main responsible of the so-called "fatbergs" balls of fat sometimes very big in size ( in London one about 250 m long was found) , that can clog the sewerage system, break the pipes , and flood the street s with sewage - usually unhealthy, dirty, and smelly . For this reason, compulsory consortiums were established also for used cooking oils , as it had already occurred for mineral ones .

Many of these fats are used for producing biolubricants and biofuels . However, also these biolubricants after use must be disposed of and show problems similar to those of non edible used oils .

US 2020/ 0 224 121 discloses methods to treat residues of soap, in a way to generate free fatty acids and/or fatty acids derivatives , trans forming basically all the soap residue into fatty acids . Feeding includes soap residues and saponifiable lipids .

WO 2009/ 158 379 discloses processes for the production of alkyl esters of fatty acids . It envisages to put into contact glycerides of fatty acids with alcohols , in the presence of a catalyst and to separate the reaction products from the catalyst and the alkyl esters of fatty acids from the reaction products . Catalysts comprise a Periodic table group VIB metal , a group TITA metal and a group VA element .

WO 2011/ 007 362 discloses a process to produce alkyl esters of fatty acids starting from one or more glycerol esters of the fatty acids or one or more fatty acids or a mixture thereof with an alcohol having 5 to 20 carbon atoms in the presence of a catalyst including oxides , mixed oxides , silicates , or sulphates of two or more of silicon, aluminium, iron, calcium, magnesium, sodium, and potas sium .

EP 1 892 232 discloses a proces s for the production of esters of fatty acids and alcohols , comprising the steps of feeding fats with oils or fats of triglycerides , partial glycerides and/or free fatty acids ; neutralising the charge by vacuum desorption at a temperature of 200 to 280 °C, providing vapour and a residue; collecting a distillate from said vapour; transesterifying the residue with an alcohol including 1 to 5 carbon atoms with an alkaline catalyst ; separating the transesterification mixture into an ester-containing fraction with 1 to 5 carbon atoms and an alcoholic fraction, a part of the free acids obtained being esterified with an alcohol in the presence of an acid catalyst , recycling the product in the feeding step .

The problem underlying the invention is to provide a recovery process for fat substances of different nature , which overcomes the disadvantages mentioned above and which allows safe disposal and enhances wastes of fatty nature . This ob ject is obtained by a process for the production of lubricating biooils starting from soaps , used cooking oils (UCO) , animal fats , refined used cooking oils (RUCO ) , used biolubricant s , wherein a soap acidification step and a hydrolysis step of the other waste to be regenerated is envisaged, in order to obtain fatty acids , characterised in that the products of these two steps are then reacted with monoalcohols and polyalcohols , to esterify them, to obtain lubricating biooils and solvent s , and in that the reaction products of used mineral oils with a strong base are included among the soaps . Dependent claims describe preferable features of the invention . In any case, further features and advantages of the invention will be better apparent from the following detailed description of a preferred embodiment, given only by exemplary and not limiting way and illustrated by the only enclosed figure, which represents a scheme of the process according to the present invention .

As mentioned, the present invention relates to a process for the production of lubricating biooils and solvents starting from some wastes, mainly fats and surfactants.

As it can be seen in the attached figure, a feed 1 takes used cooking oils to a reactor 2, while a feed 3 takes water there. According to an alternative embodiment, feed 1 may also take waste biolubricants. Reactor 2 is equipped with a stirrer 4, which can be a blade stirrer as illustrated, but it may also be of any other known type. A further feed 5 carries zinc oxide (ZnO) . The reactor outputs a flow 6, that feeds a separator 7, which outputs two flows, one of product 8 and one 9, leading to a three-way valve 10. The three-way valve 10 outputs a flow 11 and a flow 12. The flow 12 feeds a tank 13, which outputs a flow 14 feeding a three- way valve 15, where also another flow 16 arrives.

A flow 17 starts from the three-way valve 15, which is a mixture of flows 14 and 16, that feeds a distillation column 18. The distillation tail 19 contains product and the head 20 feeds a three-way valve 21; other two flows, 22 and 23, feed two tanks, 24 and 25 respectively. A flow 26 starts from tank 24, which splits in two flows. One flow 27 feeds a reactor 28, while a flow 29 feeds a distillation column 30.

Reactor 28, in addition to flow 27, is also fed with sulphuric acid from flow 31 and soaps from flow 32. Reactor 28 outputs flow 33, that feeds a decanter tank 34. Pipe 11 also merges into the pipe 33. Flow 16 exits the decanter tank 34 and merges into the three-way valve 15, and with the product flow 35.

Turning now to tank 25, in addition to pipe 23, also pipe 36 merges into it, including the distillation tails of column 30. Tank 25 outputs flow 37 that merges into the three-way valve 38. Turning back to column 30, it also outputs a head flow 39 feeding a tank 40, a pipe 41 that exits it merges into the three- way valve 38.

Examining the three-way valve 38, the flow 42 that exits it, containing a mixture of flows 37 and 41, feeds a reactor 43, equipped with a blender 44.

Reactor 43, in addition to flow 42, also receives flow 45, containing zinc oxide, flow 46, containing waste fatty acids and flow 47, coming from the three-way valve 48, where two flows merge, one, 49, containing 2-ethyl-hexanol and the other, 50, containing polyalcohols .

Reactor 43 outputs flow 51, feeding a separator 52, which outputs flow 53, that mixes with flow 5 entering the reactor 2, and one 54 feeding the three-way valve 55, which outputs two flows 56, 57. Flow 56 feeds a tank 58, which outputs flow 59 feeding a reactor 60, while flow 57 feeds a tank 61, which outputs a product flow 62.

Also flow 63 containing hydrogen merges into reactor 60, while it outputs a product flow 64.

Hereinafter, the process according to the present invention is described, always based on the attached figure.

In reactor 2 a hydrolysis reaction of used cooking oils takes place and, possibly of used biolubricants. Zinc oxide, coming both from feed 3, and from flow 53 -where it is present mainly as a zinc soap-, coming from the separator 52, is used as a catalyst for the process. Normally, an oils/water/catalyst ratio between 100:40:1 and 200:50:5 by weight is used. A preferred embodiment, leading to the best results, envisages a 150:45:3 ratio. Temperature ranges from a minimum of 170°C to a maximum of 250°C; preferably, temperature ranges from 200 to 210°C. A working pressure comprised between 10 and 30 bar is employed, preferably between 13 and 20 bar. With a reaction time between 3 and 10 hours, preferably between 5 and 8 hours, continuously, semi- continuously or batchwise.

Reactor 2 outputs, in flow 6, a mixture of water, and possibly raw glycerol -which can be advantageously used as a base for cosmetics- and/or polyalcohols, which can be used for other manufactures -in addition to the esterification step of the present process that will be disclosed later- and, anyway, that constitute one of the by-products of this process, and fatty acids. Separator 7 separates water and possible raw glycerol and polyalcohols in flow 8 and fatty acids in flow 9.

Flow 9 is splitted in the three-way valve 10. Flow 12 goes to tank 13, where the product is purified and sent, through flow 14, to the three-way valve 15. Flow 11, instead, merges with flow 33. The latter, comes from reactor 28, where waste soaps - optionally including reaction products of used mineral oils with a strong base- fed into 32, are acidified with sulphuric acid fed in 31, mentioned and described in the introduction. In reactor 28, the sulphuric acid/soap mixture has a ratio ranging from 1:3 to 3:1 by weight. Preferably, such ratio is 2:1. As a sulphuric acid, an aqueous solution of 70 g/1 in concentration is generally used, which provides a suitable level of acidity, without damaging the plant, though. Reaction temperature ranges between 50 and 150°C, preferably between 80 and 120°C. A particularly preferred temperature is 90°C. Preferably, the acidification reaction is carried out under an inert atmosphere, advantageously under nitrogen, in order to prevent side reactions that would lower the yield of the process. Reaction time ranges between 0.5 and 4 hours, preferably between 1 and 2 hours. Output flow 33 contains fatty acids, that mix up with those coming form flow 11, feeding then the decanter tank 34. Output flow 35 from the decanter tank 34 contains water and salts, representing the only actual waste of the process according to the present invention, while purified fatty acids, through the pipe 16, are fed into the three-way valve 15.

Advantageously, when feeding the soaps obtained by alkalinisation of used oils with a strong base, a preliminary treatment thereof with hexane, and distillation can be foreseen, so obtaining the removal of residual oils, with a purer soap.

Pipe 17 exiting the three-way valve 15 leads to the distillation column 18. Its distillation tails, exiting through pipe 19, contain heavy fractions of fatty acids, as by-products. Heads, exiting through 20, are fed to the three-way valve 21, where the flow is splitted. Flow 22 goes to tank 24, that outputs flow 20, which goes to reactor 28 for admixing with acidified soaps, which are mainly fatty acids. From flow 20, though, pipe 29 leads a part of the purified fatty acids to the distillation column 30. Distillation tails go to tank 25, where distillation heads of column 18 have already arrived, while heads go to tank 40 through pipe 39. Distillation allows to begin the splitting into various final products, depending on their chemical formula, obviously according to their molecular weight.

After purification in tank 40, the product is sent, via pipe 41, to the three-way valve 38, where also pipe 37 arrives, which carries purified fatty acids coming from tank 25.

Flows 41 and 37, arrived to the three-way valve 38, admix and, through pipe 42, are fed to reactor 43. In addition to fatty acids arriving through pipe 42, also a first alcohol, usually a monoalcohol, for example 2-ethyl-hexanol, fed in 49, and/or a second alcohol, usually a polyalcohol, for example trimethylolpropane, fed in 50, passing through pipe 47; optionally other fatty acids, fed in 46; and zinc oxide, fed in 45 arrive to reactor 43. Optional addition of other waste fatty acids in 46 is useful, according to a preferred embodiment, to adjust the viscosity of the final product.

In reactor 43, under stirring by stirrer 44, esterification of fatty acids is carried out. Also in this case, zinc oxide has a catalytic function. Preferably, fatty acids/alcohol/catalyst ratios range from 100:5:1 to 100:30:5 by weight; even preferably, they range from 100:10:1 to 100:20:3. Temperature ranges from 150 to 300°C, preferably from 180 to 220°C. Reaction time ranges from 2 to 8 hours, preferably from 4 to 6 hours. Water formed is preferably removed under vacuum.

Both natural alcohols, such as ethanol and butanediol, and synthetic alcohols, such as 2-ethyl-hexanol, trimethylol-propane (TMP) and pentaerythritol can be used. The esterified product is output from pipe 51 and is fed into separator 52. Pipe 53 carries zinc oxide and recovered zinc soap to feed 5, from where it goes to reactor 2.

The liquid product goes to the three-way valve 55 through pipe 54. From the three-way valve 55 the flow is split, preferably in a differential way according to the products intended to be obtained, in flows 56 and 57. Flow 57 goes to tank 61, where biolubricants, the main product, are output.

Pipe 56 feeds tank 58, from which purified esters are output through pipe 59 and feed reactor 60, where hydrogen is fed from pipe 63. So, an optional hydrogenation step of one part of the esters obtained from the mixture of fatty acids with monoalcohols and polyalcohols is envisaged, increasing the degree of saturation of the esters produced. The flow rates of pipes 56 and 57 can be adjusted, one with respect to the other, as needed. Ratio by weight within reactor 60 is: esters : catalyst [preferably Pd (2%) , SiC>2, AI2O3] ranging between 100:0.01 and 100:1, preferably between 100:0.1 and 100:0.5. Partial pressure of hydrogen ranges between 2 and 10 bar, preferably between 3 and 7 bar, most preferably being 5 bar. Reaction temperature ranges between 90 and 180°C, preferably between 100 and 150°C, most preferably being 130°C. Reaction time ranges between 10 minutes and 2 hours, preferably between 15 minutes and 1 hour. Pipe 64 discharges the final product, consisting of biolubricants and, sometimes, solvents. The product discharged from pipe 64 is part of the main product too. That is, the main product, with the highest value added, is output from pipes 62 and 64.

As it was observed, the present invention allows to obtain products with high added value, from some food and lubrication wastes, which can be used in the industry as solvents or for the production of lubricants. There are also by-products, with a lower added value, such as heavy fatty acids, glycerol and polyalcohols, always useful and marketable, recovering almost everything that was discarded. In practice, the present invention allows to recover products with high added value, completely eliminating the need of disposal treatments for some wastes. In particular, disposal of product s of used mineral oils treated with strong bases would be problematic, given the strongly polluting nature of these substances . For this reason, the present invention is particularly advantageous .

In this way, with a good relevant waste collection, said product s can be obtained at relatively moderate costs , relieving problems , such as the fatberg and the like , of the same kind, and additionally reducing the consumption of starting raw materials .

As it was also observed, one or more distillation and/or desorption steps can be envisaged for the purification of products of one or more steps that constitute the proces s , so obtaining more valuable product s .

Anyway, it should be understood that the invention should not be considered limited to the particular arrangement described above , which makes up only one exemplary embodiment , but that dif ferent variations are pos sible, all within the reach of a skilled technician, without therefore leaving the scope of protection of the invention it self , as defined by the following claims .

LIST OF REFERENCE NUMBERS

1 Feed ( of 2 )

2 Reactor

3 Feed ( of 2 )

4 Stirrer (of 2 )

5 Feed ( of 2 )

6 Pipe

7 Separator

8 Water discharge

9 Pipe

10 Three-way valve

11 Pipe

12 Pipe

13 Tank

14 Pipe

15 Three-way valve

16 Pipe 17 Pipe

18 Distillation column

19 Heavy fractions of fatty acids discharge

20 Pipe

21 Three-way valve

22 P ipe

23 Pipe

24 Tank

25 Tank

26 Pipe

27 Pipe

28 Reactor

29 Pipe

30 Distillation column

31 Feed (of 28 )

32 Feed (of 28 )

33 Pipe

34 Decanter tank

35 Water and salts discharge

36 Pipe

37 Pipe

38 Three-way valve

39 Pipe

40 Tank

41 Pipe

42 Pipe

43 Reactor

44 Stirrer ( of 43 )

45 Feed (of 43 )

46 Feed (of 43 )

47 Pipe

48 Three-way valve

49 Feed (of 43 )

50 Feed (of 43 )

51 Pipe

52 Separator 53 Pipe

54 Pipe

55 Three-way valve

56 Pipe 57 Pipe

58 Tank

59 Pipe

60 Reactor

61 Tank 62 Main product discharge (of 61 )

63 Feed (of 60 )

64 Main product discharge (of 60 )