DE1086836B - Process for avoiding the formation of mercaptans during the desulphurisation of petrol hydrocarbons - Google Patents

Description

The present invention relates to a method for the desulfurization of petroleum-hydrocarbon products boiling in the range of raw gasoline, whereby this with a desulfurization catalyst in a known manner in the presence of hydrogen with the addition of Hydrogen sulfide are brought together, and relates to compliance with certain reaction conditions here in order to obtain a desulphurised product with improved properties.

The details of this process are that the (boiling within about 135 to 225 ° C) feed of the gasoline hydrocarbons in the presence of a desulfurization catalyst with about 4.4 to 35.4 (preferably 8.9 to 17.9) m ³ Hydrogen per hl feed and with hydrogen sulfide (H ₂ S) at about 260 to 400 ° C, the space velocity about 1 to 16 volumes of feed per volume of catalyst per hour (V / V / hour), the reaction pressure between about 3 , 5 and 21.2 atmospheres and the hydrogen partial pressure are about 3.5 and 10.6 kg / cm ² . The special feature of the present process is that 0.1 to 10 mol percent hydrogen sulfide (based on the total charge) is added to the reaction mixture and the reaction conditions are set so that the mercapt number is 0.1 to 5 and corresponds to the following equation:

M = 17.8 + 0.43 (v / v / hour) + 1.3 (mole percent H ₂ S)

- 0.03 (1.8 Tr + 32),

where Tr is the temperature in ° C.

It has been found that when resinous raw gasolines from petroleum hydrocarbons are combined better desulfurization with hydrogen and hydrogen sulfide in the presence of a desulfurization catalyst and an improvement in the color properties of the Saybolt products can be achieved. aside from that it was found that the tendency, which is present in this reaction to form hydrogen sulphide, is present undesired mercaptans by regulating the reaction conditions in the manner indicated above can be largely switched off. The resin content of the products is also in the present process much lower.

Presumably, the hydrogen sulfide added prior to desulfurization tends to mix with certain components of the feed with the formation of tertiary mercaptans, initially not in larger quantities to implement the type present in the charge and thereby the undesired impurities mentioned to build; this tendency is largely suppressed when the reaction conditions are approximately as indicated above are.

The above-mentioned mercapt number is the usual potentiometrically determined value.

Procedure for avoidance

the formation of mercaptans
in the desulfurization of gasoline hydrocarbons

Applicant:

ίο Esso Research and Engineering Company, Elizabeth, N. J. (V. St. A.)

Representative: Dr. W. Beil, lawyer,
Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority:
V. St. v. America 6 September 1955

The feed for the process according to the invention can be from a crude oil or from a thermal or catalytically treated part of such oils originate. So she can use an untreated raw gasoline, one through thermal or catalytic cracking of such an oil or a fraction thereof or a raw gasoline that is used in the polymerization of lower-boiling unsaturated hydrocarbons, such as ethylene, propylene or butylene, is obtained.

Examples of suitable catalysts are the oxides and sulfides of such metals as V, Cr, Mn, Fe, Co, Ni, Mo, W and the oxides of platinum and palladium. Typical examples are also cobalt molybdate, nickel-tungsten sulfide, Cobalt sulfide, molybdenum oxide, nickel sulfide and tin sulfide. All of these catalysts are preferably used in crushed form on a carrier, such as clay or magnesia, which still contain silica can, or on silica itself, kieselguhr or zinc oxide. The catalyst can be used as a resting layer or in the form of a fluidized bed or in any suitable known manner.

The hydrogen required for the process can be supplied in the pure state or from a Mixture of hydrogen and an inert gas.

Hydrogen that was not consumed during the desulfurization can also be recycled.

The amount of hydrogen sulfide to be added should preferably be about 0.1 to 5 mole percent of the total

009 570/369

loading amount. The total amount of the added oil, hydrogen, of hydrogen sulfide and any inert gaseous substances.

The hydrogen sulfide to be added can be that normally in the gaseous hydrogen-containing feed gas be contained hydrogen sulfide, or you can separately add hydrogen sulfide from a source outside the system.

Preferred temperatures in the process are approximately 285 to 370 ^° C., preferred space velocities approximately 2 to 6 V / V / hour. and preferred pressures about 10.5 to 17.6 kg / cm ² . The pressure in the reactor and the hydrogen feed rate should be coordinated with one another in order to achieve the desired partial hydrogen pressure of about 3.5 to 10.6 kg / cm ^{2 in the reaction vessel.}

The method according to the invention will now be described in more detail with reference to the drawings.

Fig. 1 is a schematic of a preferred embodiment of the present process;

Figures 2 to 5 are graphs showing the influence of the reaction conditions on the percentage Explain the degree of desulphurisation, the Saybolt color and the resin content of the products.

In Fig. 1, the gasoline charge to be treated is through a feed line 12 together with hydrogen and Hydrogen sulfide flowing in through line 14 is passed into a reactor 10 which contains a desulfurization catalyst and at the desired temperatures is operated. After the reaction, the reaction products pass through line 16 via a Cooler 18 into a separator 22, from which the liquefied condensates are either taken as such or flow through line 24 into a fractionation column 28 while the gaseous products withdraw through line 26. The desulphurized gasoline is obtained as the top product from column 28, while the residue drains off at 32.

The gases withdrawn from the separator 22 through the line 26 or a part thereof can either at 34 leave the system if it is not important to reuse them, or they will be again into the line 14 and into the reactor 10, either through the line 38 with the valve 36 directly into the line 14 or through the lines 48 and 58 via a scrubber 52, which by the line 54 is charged with alkali to scrub the hydrogen sulfide from the gases; the spent caustic drains off at 56. You can use the Lines 38 and 58 together with the feed line 44 for pure or almost pure hydrogen and the line 40 for pure hydrogen sulfide, the desired ratio of hydrogen in line 14 as required and hydrogen sulfide while maintaining the desired pressure ratios and the partial hydrogen pressure produce. Valves 36 and 50 in the transfer lines for the exhaust gases containing hydrogen sulfide, as well as 42 and 46 in the clean gas supply lines are used to precisely regulate the gas flows when the gases are mixed together the desulfurization of other gasoline.

Influence of hydrogen sulfide
on desulfurization

example 1

Mixtures were catalytically and thermally cracked naphthas having boiling ranges from 135 to 215 ° C over a Kobaltmolybdatkatalysator on a silica-free alumina carrier in the presence of hydrogen in a series of experiments under different operating conditions, namely temperature 288-371 ⁰ C, 6 to 16 V / V / Hours, 4.45 to 26.50 m ³ H ₂ / hl oil, 3.50 to 14.05 kg / cm ² excess pressure and with up to about 10 mol percent H ₂ S, based on the total reactants fed in, desulfurized. On the basis of these data it was found that the degree of desulfurization achieved under otherwise identical process conditions, as shown in the following table, is improved by the supply of H ₂ S from sources outside the system.

Table I.

Percentage desulfurization at 315 ° C, 8 V / V / hour, 17.70 m ³ H ₂ / hl and 14.06 kg / cm ² overpressure

Mole percent H ₂ S in the
incoming reaction participants

0
1
3
5

Percentage reduction
the sulfur content of the
cracked petrol

20.3

24.6
33.5
42.5

This means that you can regulate the percentage desulfurization by regulating the amount of hydrogen sulfide can. This is also shown by the values found below under compliance with the same process conditions:

Table II

Percentage
reduction
of the sulfur
salary adding
Mole percent
H ₃ S Required
space
speed temperature
⁰ C 28.4
28.4
28.4 0
1.9
4.2 4th
8th
4th 315
315
287

The influence of additional hydrogen sulfide on the degree of desulfurization achieved is shown graphically in Fig. 2 shown. It can be seen that the percentage desulphurization under otherwise identical process conditions increases with the content of additional hydrogen sulfide.

As already stated, the Saybolt paint properties can also be improve the desulphurized petrol by being in the presence of hydrogen sulphide desulfurized. This is shown by the following examples.

Example 2

A mixture of cracked naphthas having boiling ranges from 135 to 225 ° C in the presence of a Kobaltmolybdatkatalysators, another part of this mixture in the presence of a Molybdänoxydkatalysators (both catalysts were supported on alumina) at 315 and 345 ⁰ C with hydrogen in the presence of different amounts of hydrogen sulphide desulfurized. The Saybolt color properties of the batch on the one hand and the products on the other were measured, and the differences in the Saybolt color shades

were noticed. The results are shown in Tables III and IV.

Table III Molybdenum Oxide Catalyst

Example 3

Treatment Mole percent H ₂ S addition Saybolt coloring of the
Product minus temperature
⁰ C to those entering
Respondents Saybolt stain the
feed 345 0 + 12 1 + 20.5 2 + 24 3 + 25.5 4th + 26 5 + 26 6th + 25 7th + 24 315 0 + 20 1 + 26 2 + 28.5 3 + 29 4th + 29 5 + 28.5 6th + 27.5 7th + 26

Table IV Cobalt Molybdate Catalyst

Treatment Mole percent H ₂ S addition Saybolt coloring of the
Products ^ πτΐπτι «» temperature
⁰ C to those entering
Respondents Λ * A. ^ * V ^ U ^^ UwO II ' ¹¹¹ IjI ο
Saybolt stain the
feed 315 0.5 + 27 1.0 + 29 2.0 + 33 3.0 + 36 4.0 + 38 5.0 + 39 343 0.3 + 23 1.0 + 36 2.0 + 40 3.0 + 40 4.0 + 39 5.0 + 39

These results are shown graphically in Figures 3 and 4 of the drawings, respectively. From Fig. 3 it can be seen that when using a molybdenum oxide catalyst the improvement of the Saybolt paint properties progressively increases as the percentage of hydrogen sulfide is increased to about 4 mole percent, after which it shows a slight tendency to decrease in achievable improvements.

It can be seen from FIG. 4 that the color properties are improved when a cobalt molybdate catalyst is used According to Saybolt, less improvement is possible if less than about 0.5 mol percent hydrogen sulfide is added, that, however, with larger amounts of hydrogen sulfide, the extent of the improvement in the color properties according to Saybolt increases progressively.

As stated above, according to the invention, the resin content can be reduced by desulphurising in the presence of hydrogen while keeping the partial hydrogen pressure between about 3.50 and 10.55 kg / cm ² ; this is demonstrated by the following examples.

Several experiments were carried out with a molybdenum catalyst under the following process conditions: treatment temperature 260 to 370 ° C., space velocity 2 to 12 V / V / hour. Liquid, total pressures 3.5 to 17.6kg / atü, 4.4 to 35.4m ³ H ₂ / hl oil when using mixtures of raw gasoline with a boiling range of about 135 to 225 ° C, produced by catalytic and thermal cracking (and in some cases contained small amounts of petroleum derived from the thermal polymerization of olefins); the raw gasoline contained about 13 to 33 mg resin / 100 cm ³ (test method according to General Motors Gum). In these tests it was found that the resin content of the treated raw gasoline is mainly determined by the partial pressure of the hydrogen in the reactor, as the data in the following table show:

Table V
Molybdenum oxide catalyst

Partial hydrogen pressure Average resin content in the reactor of the product (General kg / cm ² absolute Motors Gum) in mg / 100 cm ³ 1.76 5.7 3.52 4.0 6.33 2.6 8.80 3.4 10.54 4.2 12.30 5.4

With a cobalt molybdate catalyst, similar beneficial effects were achieved by changing the partial pressure of hydrogen; however, changes in temperature were also significant with this catalyst. Temperatures of 315 ° C and higher were found to be most effective in reducing the resin content for the same partial hydrogen pressure. In this FaE, the raw gasoline charge contained about 13 mg resin / 100 cm ³ (General Motors). The effects of changes in partial hydrogen pressure over a temperature range of 288 to 343 ° C can be seen from the following data:

Table VI
Cobalt molybdate catalyst

Partial hydrogen pressure
in the reaction vessel
kg / cm ² absolute Resin content (General
Motors) in mg / 100 cm ³ 4.22
7.03
9.84 3.8
2.9
2.0

The results obtained with the molybdenum oxide catalyst are shown graphically in FIG. From Fig. 5 it can be seen that the resin content decreases most when the partial hydrogen pressure in the reactor is between about 3.5 and 10.5 kg / cm ² ; the best results corresponded to a partial pressure of about 5.6 to 7.0 kg / cm ² absolute.

The formation of tertiary mercaptans during the desulfurization becomes strong according to the invention suppressed that one expresses the reaction conditions

selects that they correspond at least in part to the above-mentioned mercaptane number equation. This is going through the following examples are shown.

Example 4

A mixture of catalytically and thermally cracked raw gasoline was over a cobalt molybdate catalyst desulfurized on a silica-free alumina carrier. This mixture had a boiling range of about 135 to 225 ° C and a mercapt number of about 0.9. Different amounts were used for desulfurization

Hydrogen sulfide is added under the following reaction conditions: temperature 315 ° C., pressure 14.1 atm., Space velocity 8 V / V / h, hydrogen addition rate about 17.70 m ^{3 of} hydrogen per hl of charge. The desulfurized product was examined for its mercaptan number, Saybolt color and its resin content. The amounts of hydrogen sulfide added and the results are shown in Table VII. The calculated mercapt number of the products could also be derived from the mercapt number equation and is also listed in the table.

Table VII

Results obtained when the raw gasoline feed was desulphurized over cobalt molybdate at 315 ° C., 8 V / V / h, 14.1 atmospheres and 17.70 m ³ H ₂ per hl feed

Ver Added
Amount of H ₂ S the Mercapt number of the products Saybolt stain the the Ver Resin content
(mg per 100 cm ³ ) the
■ p_ _n Hydrogen- search
No. in mole percent
the whole feed of the products (calculated) *) feed Products improvement the JrXO-
dukes LClI Ui UCK
(kg / cm2
Overpressure) feed 0.9 (found) 4.2 - 11 + 15 + 26 feed 1.0 8.40 1 0.7 0.9 3.2 4.4 -11 + 19 + 30 13.4 5.2 8.40 2 0.9 0.9 3.6 4.8 -11 + 28 + 39 13.4 1.4 8.40 3 1.2 0.9 2.9 8.4 -11 + 27 + 38 13.4 2.4 8.40 4th 4.0 8.5 13.4

*) From the equation

M = 17.8 + 0.43 (v / v / hr) + I3 (mole percent H ₂ S) - 0.03 (1.8 Tr + 32).

It can be seen from Table VII that, under the particular reaction conditions used, the mercaptan numbers of the products (both those found and those calculated) increased with the amount of hydrogen sulfide. The test series shows z. B. that one must not add more than about 1.2 mol of H ₂ S if the desulfurized product is to have a mercapt number below about 5 under the respective reaction conditions.

In Table VII it should also be noted that in each If the Saybolt color of the products, based on the Saybolt color of the starting gasoline, is significantly improved and that the resin content also decreased noticeably.

Another possibility is to change the reaction conditions, for example, so that the Ver It is possible to use larger amounts of hydrogen sulfide without increasing the mercapt number of the product. This possibility is shown by the following example.

35

Example 5

The raw gasoline mixture according to Example 4 was over a cobalt molybdate catalyst with hydrogen and desulfurized various amounts of added hydrogen sulfide under the reaction conditions of Example 4, with the difference, however, that the reaction temperature was about 343 ° C. The amount of added Hydrogen sulphide, the hydrogen partial pressure in the reaction zone and the mercapt number, the Saybolt color and the resin content of the products are shown in Table VIII.

Table VIII

Ver Added
Amount of H ₂ S the Mercapt number of the products Saybolt stain the the ■ Ver Resin content
(mg per 100 cm ³ ) the Hydrogen- search-
No. in mole percent
the whole feed of the products (calculated) *) feed Products improvement the dukes (kg / cnv> feed 0.9 (found) 3.0 -11 + 29 + 40 feed 1.0 5 1.2 0.9 1.85 3.44 -11 + 28 + 39 13.4 1.2 8.40 6th 1.3 0.0 2.24 5.90 -11 + 26 + 37 13.4 3.4 8.40 7th 3.2 6.32 13.4 8.40

*) From the equation

M = 17.8 + 0.43 (v / v / hr) + 1.3 (mole percent H ₂ S) - 0.03 (1.8 Tr +

From Table VIII it can be seen that in these experiments the reaction conditions are a marked improvement the Saybolt color and a noticeable reduction in the resin content.

It should also be noted in this example that the addition of 1.2 mole percent hydrogen sulfide results in a product with a mercapt number of about 2 (calculated mercapt number 3). If you try this Comparing with Experiment 3 of Table VII, it turns out that at the higher temperature a significant lower mercaptan number of the product with the same charge and the same amount of hydrogen sulfide added was obtained.

As shown in the following example, similar results can be achieved with other desulfurization catalysts.

Example 6

The raw gasoline mixture according to Example 4 was made in the presence of hydrogen and various high levels of hydrogen sulfide and in the presence of a molybdenum oxide catalyst under the following reaction conditions desulfurized: temperature about 343 ° C, pressure about

14.1 atmospheres, space velocity about 4 V / V / hour, hydrogen addition rate about 17.7 m ^{s of} hydrogen per hl of charge. As in the previous examples, the desulphurized products were tested for their mercapt number, Saybolt color and resin content. The results are summarized in Table IX:

Table IX

Results which were obtained during the desulphurization of the raw gasoline feed using molybdenum oxide at 343 ^° C., 4 V / V / hour, 14.1 atmospheres and 17.70 m ³ H ₈ per hl of feed material

Ver Added
Amount of H ₂ S the Mercapt number of the products Saybolt stain the the ■ Ver Resin content
(mg per 100 cm ³ ) the Hydrogen- search
No. generally mole percent
the whole feed of the products (calculated) *) feed Products improvement the dukes (kg / cm ²
Overpressure) feed 0.9 (found) 2.5 -11 + 14 + 25 feed 2.2 8.40 8th 1.67 0.9 1.9 3.9 -11 + 15 + 26 13.4 4.0 8.40 9 3.01 0.9 4.7 6.0 -11 + 13 + 24 13.4 4.0 8.40 10 3.43 5.1 13.4

*) From the equation

M = 17.8 + 0.43 (v / v / hr) + 1.3 (mole percent H ₂ S) - 0.03 (1.8 Tr + 32).

Table IX shows that again there was a marked improvement in Saybolt stain and a significant reduction the resin content has been reached.

With regard to the mercaptan numbers, it should also be noted that, as in the previous examples, the amount of the hydrogen sulfide introduced into the desulfurization zone is the mercaptan number of the product obtained clearly influenced. Again, as the amount of hydrogen sulfide increased, the mercapt number of the product became higher.

Example 7

The rate of hydrogen addition does not significantly affect the mercapt number of the products, as by the results shown are obtained from the desulfurization of a mixture of catalytically and thermally cracked Raw gasoline with a feed mercapt number of approximately 0.6 over a cobalt molybdate catalyst were obtained. The reaction conditions and the results obtained are given in Table X.

Table X
Results obtained when the raw gasoline feed is desulphurized over cobalt molybdate

attempt

Added
Amount of H ₂ S

temperature

Space velocity
speed
(V / V / hour)

H ₂ addition rate

( ^mÄ / hl feeding) pressure

(kg / cm ² overpressure)

the
feed

Mercapt number

of the products
(found)

of the products (calculated) *)

1.4

3.0

315
315

6th
6th

35.40 17.70

14.06 14.06 0.6
0.6

*) From the equation

M = 17.8 + 0.43 (v / v / hr) + 1.3 (mole percent H ₂ S) - 0.03 (1.8 Tr + 32).

1.8
5.6

2.7 7.3

From Table X it can be seen that experiments 11 and 12 were carried out with the same reaction temperature, the same space velocity and the same pressure. Run 11 added about 1.4 mole percent hydrogen sulfide. The hydrogen addition rate was about 35.4m ³ / hL feed. In Run 12, about 3 mole percent hydrogen sulfide was added and the hydrogen addition rate was about 17.70 m ³ / hL gasoline charge. It should be noted that the mercapt numbers found for the products agree well with the calculated mercapt numbers and that the (found and calculated) mercapt numbers of the products were again clearly influenced by the amount of hydrogen sulfide added.

Claims (2)

Patent claims: 1. Process for avoiding the formation of mercaptans during the desulfurization of gasoline hydrocarbons in the boiling range of raw gasoline, the hydrocarbons being treated with hydrogen in the presence of a desulfurization catalyst and hydrogen sulfide at 260 to 400 ° C and the space velocity 1 to 16 V / V / hour, the Reaction pressure from 3.5 to 21.2 atmospheres, the partial hydrogen pressure from 3.5 to 10.6 kg / cm ² and the amount of hydrogen from 4.4 to 35.4 m ³ / hl, characterized in that the reaction mixture is 0.1 to 10 mol percent hydrogen sulfide (based on the total charge) is added and the reaction conditions are set as follows 009 570/369 sets that the mercapt number is 0.1 to 5 and corresponds to the following equation: M = 17.8 + 0.43 (V / V / hour) + 1.3 (mole percent H ₈ S) - 0.03 (1.8 Tr + 32), where Tr denotes the temperature in ^0C. 2. The method according to claim 1, characterized in that that the catalyst is a known cobalt molybdate or molybdenum oxide catalyst located on a carrier is. Considered publications:
German Patent No. 930 223;
German interpretative document No. 1 020 142. 1 sheet of drawings