EP0728175A1

EP0728175A1 - Process for dechlorination of a spent oil fraction

Info

Publication number: EP0728175A1
Application number: EP95930569A
Authority: EP
Inventors: Michel Laborde; Philippe Dolbecq
Original assignee: Total Raffinage Distribution SA
Current assignee: TotalEnergies Marketing Services SA
Priority date: 1994-09-13
Filing date: 1995-09-11
Publication date: 1996-08-28
Anticipated expiration: 2015-09-11
Also published as: JPH09507878A; WO1996008546A1; CA2176210C; ATE186563T1; JP4027417B2; FR2724391A1; DE69513277D1; CA2176210A1; EP0728175B1; DE69513277T2; US5783068A; FR2724391B1

Abstract

PCT No. PCT/FR95/01162 Sec. 371 Date May 13, 1996 Sec. 102(e) Date May 13, 1996 PCT Filed Sep. 11, 1995 PCT Pub. No. WO96/08546 PCT Pub. Date Mar. 21, 1996The present invention relates to a process for dechlorinating a spent lubricating oil fraction, optionally mixed with another hydrocarbon stock. Upstream of the recycling operation in refining the spent oil, the latter is subjected to a dechlorination operation at least partially by passing it on a bed of particles (6) of a composition which neutralizes by absorption and containing, as active compound capable of fixing the chlorine, at least one metal oxide and/or at least one metal hydroxide.

Description

Process for dechlorinating a fraction of used oil.

The present invention relates to a process for dechlorinating a fraction of used oil. We know that used lubricating oils, recovered in garages or service stations, represent very large tonnages, which, for France, amount to 100,000 tonnes, for example 120,000 tonnes per year.

It has therefore always been sought to avoid landfilling these used oils, which would risk constituting an important factor of pollution and, currently, these oils are usually subjected to a regeneration treatment.

This treatment is however expensive, because the used oils have a significant content of various metals and of chlorine, and the regenerated oils are practically as expensive as the new oils coming from refinery.

We have therefore been led to consider other uses for these used oils, for example as fuel, in particular in cement factories, but, also in this application, the presence of high chlorine contents (approximately 400 to 2,000 ppm) is problematic. .

It has therefore been proposed to recycle these used oils in the refinery, to subject them to distillation, possibly in mixture with other feeds, in order to recover at least a fraction of the interesting compounds which they contain.

The preliminary tests carried out for this purpose by the Applicant have however shown that, in such a use, the chlorine compounds contained in the used oils again pose serious problems. These compounds are, in fact, organic chlorides, originating from additives for oils, which generally include chlorinated compounds, in particular chlorinated polyisobutenes. During a distillation operation, even at a relatively low temperature, in particular in the presence of water vapor, the molecules of these chlorinated compounds break and give rise, in particular, to hydrochloric acid, which has a marked corrosive effect on refining installations.

The present invention therefore aims to reduce the chlorine content of used oils to a rate compatible with recycling operations in refineries of these oils and it proposes, for this purpose, to use solid composite products capable of fixing the chlorinated ions. , already known in the art for other applications and under different conditions of use.

In fact, already used in industry, particulate compositions called "chlorine traps", based on alumina or metal oxides or metal hydroxides such as CaO, Na ₂ 0, K ₂ 0, MgO, as well as the corresponding hydroxides, for eliminating the chlorine present in the liquid or gaseous flows of process units, in particular in reforming or isomerization units.

These compositions have, in general, a particle size of the order of 0.5 to 3 mm and they usually neutralize the chlorine by adsorption. They are generally used at ambient temperature or of the order of at most 100 ° C. and at atmospheric pressure, and they usually retain about 15% of the chlorine present in the treated charges. The Applicant has established that such chlorine traps are particularly well suited to a partial dechlorination operation of used oils, upstream of any recycling operation in a refinery, in particular of vacuum distillation, and that, unexpectedly, their chlorine fixing power increases significantly with the temperature of the treated oils, the chlorine trap being able to retain at least 40% of the chlorine present in the treated oil at a temperature between 300 and 400 ° C. and at atmospheric pressure. As will be seen below, it is naturally possible to operate at different temperatures and / or pressures.

However, this amount of chlorine greater than 40% represents roughly the fraction of chlorinated compounds which decompose in a recycling operation for used oils or which distill in a vacuum fractionation column for used oils, leading to the formation of hydrochloric acid, and the invention therefore proposes, in a simple way, subjecting used oils to dechlorination before any recycling operation.

The invention therefore relates to a process for dechlorinating a fraction of used lubricating oil, optionally in admixture with another hydrocarbon feed, this process being characterized in that, upstream of a recycling operation in used oil refinery, the used oil is subjected to an at least partial dechlorination operation by passing over a bed of particles of a neutralizing composition by adsorption containing, as active compound capable of fixing the chlorine at least one oxide of 'a metal belonging to groups I and II of the Periodic Table and / or at least one hydroxide of a metal belonging to groups I and II of the Periodic Table.

Preferably, the active compound of the neutralizing composition will be a calcium, magnesium, sodium or potassium oxide, or alternatively a calcium, magnesium, sodium or potassium hydroxide. Even more preferred active compounds are calcium oxide and calcium hydroxide.

Preferably, the dechlorination phase will be carried out under conditions such that at least 40% and, preferably, 60% of the amount of chlorine present in the used oil is retained by the neutralizing composition by adsorption. These conditions are, for example, the following: a temperature of at least 150 ° C and, preferably, of the order of 400 ° C, an hourly space velocity of the used oil of 0.5 hi (volume d used oil, by volume of adsorbent and per hour) and a pressure substantially equal to atmospheric pressure.

An implementation at different temperatures and / or pressures is also within the scope of the invention. In a preferred embodiment of the invention, prior to the dechlorination operation, the used oil will be subjected to an atmospheric distillation phase at a temperature of 300 to 400 ° C in order to remove the water and the light solvents which it contains, and the dechlorination operation will be carried out on the used oil coming from this atmospheric distillation, possibly after heating of this oil, for example by heat exchange, to increase the efficiency of the dechlorination.

The used oil thus dechlorinated may then be subjected, for example, to vacuum distillation, preferably in admixture with another charge, such as an atmospheric distillation residue, with a view to separating in particular from gas oil under vacuum. , a vacuum distillate and a bituminous vacuum residue, without the formation, as is usual at this stage, of hydrochloric acid responsible for marked corrosion in the installations.

Naturally, the atmospheric distillation and vacuum fractionation operations or other operations on the residue thus dechlorinated will be carried out in series and continuously.

As indicated above, the dechlorination compositions used in the process of the invention are well known in the art and generally contain at least 25% by weight of active compound. They are marketed, for example, under the trade names TRAP'IT by the Company Catalysts and Chemicals Europe, SELEXSORB HC1 by the Company ALCOA, and DISCOVERY ALUMINAS by the Company Dycat International.

The preferred composition for carrying out the invention is that sold under the name TRAP'IT, which contains, in% by weight, from 23.0 to 27.0% of CaO, constituting the active product, and 43 to 53.0% zinc oxide, serving as a support, the complement to 100% consisting of a binder.

This composition generally has an apparent specific mass of 0.720 to 0.800 cm 3 / g, a pore volume of 0.35 to 0.45 cm Vg and a specific surface of at least 22 m2 / g. She is usually in the form of rods with a diameter of 1.2 to 1.8 mm and a length of about 4.0 to 12.0 mm.

An embodiment of the invention will be described below, by way of nonlimiting example, with reference to the accompanying drawings. In these drawings:

Figure 1 is a general diagram illustrating this form of implementation of the method;

FIG. 2 is a diagram illustrating the increase in the dechlorination rate, expressed in%, as a function of the temperature, expressed in ° C.

In the embodiment of the invention illustrated in FIG. 1, the used oil to be treated, arriving via line 1, is first of all topped, by atmospheric distillation, in a column 2. The water present in the used oil (4 to 10% by weight) is evacuated at the head of the column by line 3, while the light solvents are evacuated by line 4.

The topped oil, discharged at the bottom of the column, through line 5, at a temperature of 300 to 400 ° C, most often contains about 500 ppm of chlorine. It then passes through a balloon 6 containing the particulate composition used as a chlorine trap. If it is desired to dechlorinate the oil at a higher temperature, a heat exchanger 7 can be placed on line 5 upstream of the flask 6. The chlorine trap contained in the flask 6 retains about 60% of the chlorine present in the used oil, and the treated oil, which contains only about

200 ppm of chlorine is evacuated via a line 8 in the direction of a vacuum distillation column 9, into which it is introduced, for example, with an atmospheric distillation residue arriving via line 10.

The chlorine content of the treated oil is compatible with the conditions of vacuum distillation, which takes place without any particular risk of corrosion due to the formation of hydrochloric acid in column 9.

From it are evacuated in the usual way:

- at the top of the column, by line 11, a gas oil under vacuum;

- at an intermediate level, via line 12, a vacuum distillate,

- at the bottom of the column, by line 13, a vacuum residue, usable as bitumen.

Example 1 which follows relates to an application of the method according to the invention using the device of FIG. 1, it being understood that other forms of implementation are within the scope of the invention. Example 2 illustrates the improvement in the dechlorination of the treated oil as the temperature of the dechlorination treatment rises.

Example 1 This example relates to the treatment, in the device of FIG. 1, of a used oil having the following characteristics: - density: 909.9 kg / m ³ ,

- total chlorine content: 1036 ppm,

This oil is subjected in column 1 to atmospheric distillation under the following conditions: transfer temperature: 360 ° C., atmospheric pressure.

Is collected, in% by weight, by line 3, 3.7% of water and, by line 4, 5.5% of light chlorinated solvents.

The topped used oil, collected at the bottom of the column by line 5, at a temperature of 360 ° C., contains 325 ppm of chlorine. It is subjected to this temperature of 320 ° C., in the flask 6, to a dechlorination operation, by treatment with the composition called TRAP'IT (registered trademark), the composition of which was given above. The flask 6 contains 15m ³ of TRAP'IT and the dechlorination treatment is carried out at an hourly space velocity of the treated oil of 0.5 hi.

The oil leaving balloon 6 via line 8 now contains only 123 ppm by weight of chlorine and 62% of the chlorine present in the oil at the inlet of balloon 6 have therefore been fixed and retained by the composition TRAP'IT .

The oil thus partially dechlorinated is then mixed with an atmospheric distillation residue, in the following proportions 7/100 by weight, and the mixture is introduced into the vacuum distillation tower 9, where it is processed under the following conditions:

- transfer temperature: 400 ° C

- pressure: 5.10 ³ Pa at the head of the column.

2% by weight of vacuum diesel oil, 57% by weight of vacuum distillate and 41% by weight of vacuum residue, having the following characteristics, are collected by lines 11, 12 and 13, respectively:

Diesel oil: chlorine content <50 ppm,

Vacuum distillate: chlorine content <3 ppm, Vacuum residue: chlorine content 15 ppm.

The hydrochloric acid content at the top of the column is determined by measuring the chlorides in the condensing water and it is found that the dechlorination of the used oil makes it possible to reduce the chloride content in the overhead water up to '' below 20 mg / 1 and the pH is around 5 to avoid any problems.

This example therefore clearly shows the efficiency of the process for treating used oils, by vacuum fractionation, in accordance with the invention. After use, the composition of TRAP'IT can be discarded or regenerated.

Example 2 This example aims to show the advantage of carrying out the dechlorination operation at a temperature as high as possible.

Treated in a flask containing 15m ³ of the composition TRAP'IT, at an hourly space speed of 0.5 h ^-1 , a charge of used oil containing 325 ppm of chlorine. The treatment is carried out at various temperatures and the dechlorination rate is measured each time, that is to say the fraction, expressed in%, of chlorine of the charge retained by the dechlorination composition.

The results obtained are given in Table I below: TABLE I

Dechlorination Dechlorination Temperature (° C) (%)

40 20.0

130 26.7

280 56.9

300 58.4

320 64.6

340 79.0

400 95

The results obtained have been reported in FIG. 2 and it can be seen that the dechlorination rate increases almost exponentially as a function of the temperature, which shows the advantage of carrying out the dechlorination operation at a temperature also as high as possible. For the sake of profitability, the dechlorination phase is preferably carried out at around 350 ° C.

The above examples use the TRAP'IT composition, but the DYCAT 115 composition, the characteristics of which are grouped in Table II below, is also perfectly suitable since the results are very similar to those obtained above with TRAP'IT. One can also use compositions based on soda and potash which have dechlorination properties quite similar to the compositions TRAP'IT and DYCAT 115.

The composition of DYCAT 115, in% by weight, is given in Table II below. The DYCAT 115 is in the form of spheres of approximately 3 to 5 mm in diameter. TABLE II

COMPOUNDS% by weight

Calcium oxide At least 60

Aluminum oxide 8

Manganese oxide 5

Sodium oxide 4.5

Silica 5.0

Lead <0.1

As, Cd Traces

The tests carried out by the Applicant prove that such favorable results are obtained by substituting calcium hydroxide Ca (OH) ₂ for the calcium oxide of these compositions.

The above examples clearly illustrate the advantages of the invention, which makes it possible to reuse used lubricating oils in a refinery, by means of a simple and inexpensive dechlorination pretreatment.

Claims

1. Process for dechlorinating a fraction of used lubricating oil, optionally mixed with another hydrocarbon feed, this process being characterized in that, prior to a recycling operation in the refinery of the used oil, the following is subjected the used oil in an at least partial dechlorination operation by passing over a bed of particles of a neutralizing composition by adsorption containing, as active compound capable of fixing chlorine, at least one oxide of a metal from groups I and II of the Periodic Table and / or at least one hydroxide of a metal from groups I and II of the Periodic Table.

2. Method according to claim 1, characterized in that the dechlorination phase is carried out under conditions such that at least 40% and, preferably, approximately 60% of the chlorine present in the treated used oil are retained by the adsorbent composition .

3. Method according to claim 2, characterized in that the dechlorination phase is carried out at a temperature of at least 150 ° C and, preferably, of the order of 400 ° C, and in that the hourly space speed the waste oil charge is about 0.5 hi.

4. Method according to one of claims 1 to 3, characterized in that, prior to the dechlorination operation, the used oil is subjected to an atmospheric distillation phase at a temperature of 300 to 400 ° C, intended for remove the water, and the light solvents which it contains, and in that the dechlorination operation is carried out on the used oil coming from this atmospheric distillation, possibly after reheating of this oil.

5. Method according to one of claims 1 to 4, characterized in that the active compound of the composition neutralizing by adsorption is a calcium oxide, magnesium, sodium or potassium and, preferably, a calcium oxide.

6. Method according to one of claims 1 to 4, characterized in that the active compound of the composition neutralizing by adsorption is a calcium hydroxide or magnesium or sodium or potassium, and preferably calcium hydroxide.

7. Method according to claim 1, characterized in that upstream of the dechlorination process, there is a vacuum distillation.