JPH05192507A - Method of desulfrization - Google Patents

Abstract

PURPOSE: To remove elemental sulfur in an organic substance by bringing a stream of the gaseous or liquid organic substance contaminated with the elemental sulfur into contact with an absorbent containing metal copper as an active component. CONSTITUTION: A stream 3 exiting from one of reactors 2a, 2b containing an absorbent such as zinc oxide or copper oxide is released from a reactive contaminating substance such as hydrogen sulfide and carbonyl sulfide, but still contains by-products such as water and carbon dioxide. The stream 3 passes through one of removal devices 4a, 4b, and is released from the by-products. And then the stream 3 flows into removal devices 5a, 5b containing a metal copper absorbent wherein dissolved elemental sulfur is removed and a stream of a desulfurized product 6 is produced. The preparation of the metal absorbent generally comprises the steps of the reduction of a precursor consisting of a reducing copper compound by introducing the stream 8 of hydrogen which is diluted with an inert gas stream 7 and heated to a suitable temperature for the reduction in a heat-exchanger 9 into the bed of the precursor and the exhausting of a stream 10 of an exhaust gas outside after the reduction.

Description

Detailed Description of the Invention

This invention relates to a method of removing elemental sulfur from organic compounds.

In organic liquids such as carbon tetrachloride and hydrocarbons such as benzene and petroleum, elemental sulfur is often dissolved and present as a pollutant. Similarly, organic polysulfides are often present in those liquids, and these polysulfides readily decompose to yield elemental sulfur dissolved in the liquid.
Elemental sulfur may also result from the reaction of sulfur compounds such as hydrogen sulfide with oxidants. In addition, elemental sulfur is of considerable volatility and may be present in gaseous hydrocarbon streams. Such elemental sulfur has the property of reacting with metals, causing serious corrosion problems for pumps and other equipment used to handle organic compounds. Of particular interest is the corrosion of vehicle fuel injection pumps submerged in water, which occurs when vehicle fuel contains elemental sulfur.

It is well known to remove reactive sulfur compounds such as hydrogen sulfide and carbonyl sulfide from gas or liquid streams. However, elemental sulfur is considerably more difficult to remove than reactive sulfur compounds, and existing methods of sulfur removal do little to remove elemental sulfur.

The active form of metallic copper, produced by the reduction of reducible copper compounds, is used to remove elemental sulfur from streams of gaseous or liquid organic compounds, especially elemental sulfur dissolved in streams of liquid hydrocarbons. What we can do is now discovered.

Accordingly, the present invention therefore relates to an elemental sulfur-contaminated gas or gas comprising contacting a stream of a gaseous or liquid organic substance contaminated with elemental sulfur with a sorbent containing metallic copper as an active ingredient. A method is provided for reducing the content of elemental sulfur in a stream of liquid organic material.

The process of the present invention is preferably carried out under conditions of temperature and pressure such that the stream of organic material is in the liquid state. Preferably, the process of the invention is carried out at temperatures below 300 ° C., in particular below 150 ° C. and at most 100 bar.
Achieved at pressures up to (ab.). Organic liquids suitable for treatment according to the invention include, for example, petroleum, kerosene,
Includes liquefied petroleum gas (LPG), natural gas liquid (NGL), aromatic liquid hydrocarbons and liquefied natural gas (LNG).

The initial concentration of elemental sulfur is usually 1 to 200
ppm, and typically 1 to 50 ppm (parts by weight).

Conventional absorbents, such as the zinc oxide-based absorbents used to remove reactive sulfur compounds, do not help in the removal of elemental sulfur. It has now been discovered that metallic copper can be used as an active ingredient in absorbents that are effective in absorbing elemental sulfur from organic gas or liquid streams. During the absorption process, metallic copper is converted to copper sulfide. In general, the higher the copper content of the absorber, the more elemental sulfur can be removed before the next replenishment of the absorbent. Therefore, the absorbent should be at least 30 weight percent (copper oxide (I) present in the loss free solvent after ignition of the absorbent at 900 ° C. without loss of weight).
I), expressed as a percentage), more usually 50-9
It has a copper content of 0 weight percent. The ability of absorbents to adsorb elemental sulfur is also affected by the accessibility of elemental sulfur to metallic copper. In general, higher metal surface area (specific surface area) of copper is more effective in adsorption than absorbents with comparable copper content but lower copper metal surface area. A particularly effective absorbent has a copper metal surface area of 2
Those having a surface area of 0 m ² / g or more, especially a copper metal surface area of 20 to
It is something like that in the range of 40 m ² / g. Adsorbents with a copper metal surface area greater than that, for example greater than 50 m ² / g, can likewise be used. Absorbents with high copper metal surface area
For example, it can be formed by reducing a copper compound such as copper oxide, copper carbonate or copper nitrate with a suitable reducing agent. Suitable reducing agents include hydrogen, compounds that decompose to give hydrogen in the presence of an absorbent, carbon monoxide, and mixtures of carbon monoxide and hydrogen. The conditions under which the reduction of the copper compound is conducted can be similar to those used in preparing copper-based methanol synthesis catalysts from oxidizing precursors. The temperature at which the absorbent is reduced will depend to some extent on the nature of the reducing agent. Typically the temperature is in the range 90 to 250 ° C, and usually 15
It will be in the range 0-200 ° C.

Absorbents are disclosed, for example, in US Pat. No. 4,871,
710, copper 4,996,181, copper 4,983,367
It is convenient to prepare it in the form of fine particles having a size similar to that commonly used for the removal of reactive sulfur compounds, as described in US Pat. The absorbent is a single bed (sin
gle bed) or, more usually, arranged in series and / or in co-currently arranged beds. Typically,
The flow of organic material through each bed has a liquid hourly space velocity (LHSV) of 1-20 / hr, more usually 1-
That would be enough to give 10 / hour.

Generally, the organic stream to be treated will contain other contaminants in addition to elemental sulfur. These other pollutants include hydrogen sulfide, carbonyl sulfide, organic sulfur compounds,
Arsenides and heavy metals such as mercury are included. Copper metal sorbents can be used to remove these contaminants as well as elemental sulfur. However, removal of these contaminants from the organic stream may be preceded by contacting the stream with conventional means, such as an absorbent consisting of zinc oxide and / or copper oxide, before contacting with the metallic copper absorbent. Preferably to minimize the required amount of copper metal sorbent. Some by-products such as water and carbon dioxide resulting from the reaction between pollutants and conventional sorbents are subsequently reacted with the metal copper sorbent to remove elemental sulfur from organic liquids. Reduce the effect of. Therefore, it is equally preferred to remove these reaction by-products prior to contacting them with the metallic copper absorbent.

The present invention will be described in more detail below with reference to the accompanying drawings.

FIG. 1 shows a feed stream (1) of an organic liquid which contacts one of two compatible pollutant removal reactors (2a, 2b). Isolate each reactor,
The valve means necessary for directing the flow of liquid between the following devices have been omitted from the drawing for clarity.
The reactors (2a, 2b) are hydrogen sulfides as listed above,
It is used to remove at least some of the reactive contaminants such as carbonyl sulfide and contains an absorbent such as zinc oxide and / or copper oxide. As a result of the reaction taking place in the beds (2a, 2b), stream (3) is released from the reactive pollutants mentioned above, but contains water and by-products such as carbon dioxide. Stream (3) then flows to bed (2
Flowing some of the by-products produced in a, 2b) (3)
Passes through one of the two beds (4a, 4b) which is effective for absorbing from. The stream released from the by-products then flows directly into the respective beds of metallic copper absorbents (5a, 5b), where the elemental sulfur dissolved therein is removed and desulfurized. Produce stream (6). Copper metal sorbents are commonly formed by in situ reduction of precursor materials consisting of reducing copper compounds. The reduction of the precursor is carried out by passing a stream of hydrogen (8) diluted in an inert gas stream (7) and heated to an appropriate reduction temperature in a heat exchanger (9) through the bed of precursor material. , After which the exhaust gas stream (10) is discharged.

In some cases it may be desirable to provide a regenerator for the metallic copper absorbent. This regeneration is achieved by re-reducing the waste metal copper absorbent with a stream of hydrogen. Typically the reduction is carried out with a stream of hydrogen at a temperature of 200-300 ° C. Copper sulfide produced by the reaction between copper and elemental sulfur is converted back to metallic copper with the simultaneous generation of hydrogen sulfide. Hydrogen sulfide is removed from the stream of hydrogen by scrubbing and then fed to a sulfur recovery plant, such as a claus plant.

The invention will be described in more detail with reference to the following examples.

[0015]

Example 1 In this example, two beds of absorbent were used in series (in series). The first bed is composed of 300 g of absorbent granules consisting of high surface area zinc oxide and cement binder, while the second bed is a mixture of high specific surface area copper oxide and zinc oxide and cement binder. 300g of granules formed from
It was produced by reduction in u). The mixture contained 55 weight percent copper oxide. Reduction is performed using a hydrogen stream 180
It was carried out at a temperature of ° C. From the measurements made on another sample of the mixture, the copper surface area of the second bed after reduction is 2
It was estimated to be 0 m ² / g.

Total sulfur of about 400-500 ppm (parts by weight)
A stream of liquid gasoline containing about 20 ppm of which-is elemental sulfur-with an average flow rate of about 500 ml / hour in a series bed.
Passing at 0 ° C., the content of elemental sulfur in the effluent fluid was monitored at regular intervals. The experiment was terminated when the elemental sulfur content of the discharge fluid reached 5 ppm (weight) after 87 days. The cumulative flow rate and the measured sulfur content at various elapsed times are shown in Table 1.

The waste absorbent copper oxide / zinc oxide bed was then analyzed and found to have a sulfur content of about 7.2 weight percent. Examination by X-ray diffraction (XRD) found that there was cupric sulfide but no cuprous sulfide, copper sulfate or zinc sulfide in the bed. The absence of zinc sulphide in the bed of waste absorbent copper oxide / zinc oxide means that reactive sulfur compounds such as hydrogen sulphide present in gasoline were adsorbed by the first zinc oxide bed. Is shown. The presence of cupric sulfide rather than cuprous sulfide in the bed of copper oxide / zinc oxide, a waste absorbent, indicates that copper can be regenerated by reduction with hydrogen. This is because cupric sulfide is more easily reduced to metallic copper than cuprous sulfide.

Table 1 Hour (day) Cumulative flow rate (L) Exhaust sulfur (ppm) 1 10.5 0 11 116.7 0.2 21 223.2 0.2 31 341.3 0.7 41 41 486.0 1 .0 51 628.4 1.3 61 61 765.4 2.5 73 905.0 1.6 1.6 79 974.0 * 81 * 2.8 87 * 5.0 * = Not measured

[0019]

Example 2 One concern is that metal copper absorbers are often used as octane number improvers (antiknock agents) in gasoline, methylcyclopentadiene manganese tricarbonyl (M).
It was to react with or decompose it. To test this, three catalyst beds in series, a sample of the zinc oxide absorbent of the first bed granules of Example 1, a waste absorbent of the second bed of Example 1, ie sulfurization, were used. Samples of the above granulated sorbents, and samples of the second bed fresh copper oxide / zinc oxide sorbent granules of Example 1 were loaded into a glass reactor. The air in the reactor was replaced with nitrogen and the device was wrapped in aluminum foil to shield it from light (light affects the decomposition of MMT). Next, hydrogen was passed through a continuous bed at 180 ° C. to reduce the copper compound to metallic copper. Then, xylene (70
%) And heptane (30% by weight).
5 of MMT dissolved in the above xylene / heptane mixture
A solution containing 40 ppm (by weight) is then added at 22 to 2 at atmospheric pressure.
The liquid was passed through a continuous bed for 48 hours at a liquid hourly space velocity of 2 / hour at 5 ° C. Analysis of the solution before and after passing through the bed did not reveal any change in manganese content. The reactor was then flushed with fresh solvent and purged with nitrogen. The absorbent was dried at 110 ° C. and analyzed for the presence of manganese. No manganese was detected in the zinc oxide sample, but the reduced copper sulfide containing adsorbent contained about 300-500 ppm (by weight) manganese. Manganese is a likely contaminant of cement used as a binder for granules,
Perhaps the manganese found here comes from the pollutants. Because no change in the manganese content of the solution was detected while passing through the bed. If all MMT had been degraded and adsorbed by the absorbent, the average manganese content of the absorbent bed after the experiment would have been about 3% by weight.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a method for removing elemental sulfur according to the present invention.

[Explanation of symbols]

1 Organic liquid feed stream containing elemental sulfur 2a, 2b Two compatible reactive pollutant removal devices (reaction beds) 3 Organic liquid stream after removal of reactive pollutants 4a, 4b Equipment for removing by-products generated by the reaction of reactive pollutants and absorbents (reaction bed) 5a, 5b Equipment for removing elemental sulfur by metal copper absorbent (reaction bed) 6 Flow of desulfurized products 7 Inert gas Supply line 8 Hydrogen gas supply line 9 Heat exchanger 10 Exhaust gas flow

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Peter Wood TS 23.1, England 23.1 Elby, Cleveland, Birmingham, P.O. Box 1

Claims (8)

[Claims] 1. The elemental sulfur content of a gaseous or liquid organic matter stream comprising contacting a gaseous or liquid organic matter stream contaminated with elemental sulfur with an absorbent containing metallic copper as an active ingredient. How to reduce. 2. The method according to claim 1, wherein the organic substance is a liquid having elemental sulfur dissolved therein. 3. The absorbent is at least 30 weight percent.
(Expressed as percentage of copper (II) oxide present in the absorbent without weight loss after ignition of the absorbent at 900 ° C)
A method according to claim 1 or 2 having a copper content of. 4. The method according to claim 1, wherein the absorbent has a copper metal surface area of 20 m ² / g or more. 5. A stream of organic material comprises, in addition to elemental sulfur, one or more reactive sulfur compounds, the reactive sulfur compounds comprising zinc oxide and zinc oxide before contacting the stream with a metallic copper sorbent. 5. A method as claimed in any one of the preceding claims, wherein the method is removed by passing it through a bed of copper oxide absorbent. 6. A by-product formed by the reaction of a reactive sulfur compound with a copper oxide and / or zinc oxide absorbent is removed prior to contacting the stream of organic material with the metallic copper absorbent. Item 5. The method according to Item 5. 7. The process according to claim 1, wherein after the metallic copper absorbent has been used for a certain period of time, the waste metallic copper absorbent is regenerated by reducing it with a stream of hydrogen. 8. The method according to claim 7, wherein the reduction is achieved at a temperature of 90-250 ° C.