JPH0747750B2 - Method for removing mercury in liquid hydrocarbons - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION Liquid hydrocarbons, such as NGL (natural gas condensate) recovered from natural gas, contain tens to hundreds of ppb of mercury depending on the place of origin. When NGL is used as a chemical raw material, for example, as an ethylene raw material, corrosion of the heat exchanger in the cryogenic separation process,
The deterioration of the catalyst in the step of hydrogenating acetylene, diene, etc. becomes a problem. For removing mercury in gaseous hydrocarbons such as natural gas, sulfur-supporting activated carbon has already been used, but for liquid hydrocarbons, there is no industrialized process.

[0002]

BACKGROUND OF THE INVENTION The inventors of the present invention contact a liquid or gas containing mercury with an adsorbent containing a sulfide of one or more metals selected from the group consisting of molybdenum, tungsten and vanadium. A method for removing mercury (Japanese Patent Laid-Open No. 2-2873) was proposed.

However, NGL contains ionic mercury and organic mercury in addition to elemental mercury. Although the adsorbents composed of heavy metal sulfides as described above are effective in removing elemental mercury, they are not so effective in removing ionic mercury and high molecular weight organic mercury. In order to remove ionic mercury and high molecular weight organic mercury, it is also effective to use a method of contacting with an aqueous solution such as sodium sulfide or sodium polysulfide to absorb it, but it is possible to avoid complication in the process. Absent.

[0004]

The present invention is directed to liquid hydrocarbons containing various forms of mercury, for example, crude oil such as kerosene, light oil, straight run naphtha, vacuum distillate or natural gas condensate (NGL) fraction. An object of the present invention is to provide a method for removing mercury from pyrolysis gasoline, cracked oil such as catalytically cracked naphtha, natural gas condensate and the like by a simple operation.

[0005]

The method for removing mercury in liquid hydrocarbons according to the present invention is a method for removing mercury containing liquid hydrocarbons.
It is characterized in that a gaseous component obtained by heat treatment at a temperature of 0 ° C. or higher is vaporized, and the obtained gaseous component is brought into contact with an adsorbent containing a heavy metal sulfide in a gaseous state.

Ionic mercury and high molecular weight organic mercury in the raw liquid hydrocarbons start to decompose at a temperature of 90 ° C. or higher and change to the form of elemental mercury (elemental mercury), and at 200 ° C. or higher, almost completely. Disassemble. Even if the heating temperature is less than 200 ° C and the decomposition rate of ionic mercury or high-molecular weight organic mercury is low, undecomposed matter remains in the liquid and most of the mercury that accompanies the vaporized gaseous components is elemental mercury. It was found that most of the mercury was removed by contacting the gaseous component as it was with the adsorbent containing heavy metal sulfide. From the viewpoint of the acquisition rate of the gaseous component, it is generally desirable to heat it to 250 ° C. or higher, although it depends on the type of liquid hydrocarbon. The upper limit of the heat treatment temperature should be lower than the decomposition temperature of the target hydrocarbon, and the upper limit is around 370 ° C. LHSV at the time of heat treatment is preferably 0.1 to 100 hr ^-1 , and practically ¹ to 50 hr ^-1 .

As the adsorbent containing heavy metal sulfide, Cu,
Although it is possible to use an adsorbent containing a sulfide such as V or W, one mainly containing a sulfide of molybdenum is preferable. Molybdenum sulfide has an extremely high activity of adsorbing mercury as a simple substance, but it is effective to use it as a composite sulfide in combination with cobalt and / or nickel to further improve the mercury adsorption effect of molybdenum sulfide. Is. When cobalt and / or nickel sulfides molybdenum oxide, it initiates sulfide at a lower temperature, and at the same time cobalt and / or nickel is incorporated into molybdenum sulfide crystals to prevent sintering.
As a result, a highly dispersed sulfide is obtained. The content of cobalt and / or nickel is 0.05 to 0.9 atom based on 1 atom of molybdenum, preferably 0.
It is preferably 1 to 0.8 atoms. Atomic ratio 0.05
In the following, the effect of dispersion is small, but even if it is increased to 0.9 or more, the effect does not increase so much.

These metal sulfides can be used as an adsorbent as they are, but when the adsorbent is carried on a carrier, the dispersibility of the adsorbent is improved, and not only the adsorption amount is increased but also the adsorption amount is increased. Since the speed is increased and mercury other than elemental mercury can be effectively removed, it is preferable to use it by supporting it on a carrier. As the carrier, silica, alumina, silica-
Alumina, zeolite, ceramics, glass, resin, activated carbon, or the like can be used. Particularly, the adsorbent adsorbed on alumina has high dispersibility and is excellent as the adsorbent of the present invention. Of the alumina, γ-alumina is particularly preferable.

When supported on a carrier, the supported amount of molybdenum sulfide is 1 to 20 wt% as metal, especially 5 to 15%.
A range of wt% is preferred. If the amount supported is greater than this, the effect of the carrier is small and the dispersion becomes poor. Further, when the supported amount is small, the adsorbed amount per adsorbent becomes small. When cobalt and / or nickel is added, the addition amount is preferably 0.1 to 5 wt% as a metal with respect to the adsorbent.

[0010] What support preferably so better things large specific surface area the better the contact efficiency, 5~400m ² / g, particularly preferably those having a specific surface area of 100 to 250 m ² / g, which is limited to is not.

The method of contacting the liquid hydrocarbon containing mercury with the adsorbent is arbitrary, but the fixed bed flow system is particularly preferable. Continuous operation is possible by adopting the fixed bed distribution method.

The temperature condition for the adsorption is not lower than the temperature required to prevent the liquefaction of the vaporized gaseous component, that is, the same as or slightly higher than the heating temperature (5 to 10 ° C.). G
HSV is 10 to 10,000 hr ^-1 , practically 100
It is preferably set to 5,000 hr ^-1 .

The present invention will be specifically described below with reference to examples, and will be compared with comparative examples.

[0014]

[Comparative Example 1] 10 ml of natural gas condensate containing 800 ppb (as mercury) of mercury and a mercury compound was directly placed in a glass bottle having a capacity of 30 ml without heating, and a pre-sulfurized Co-Mo-based adsorbent (Mo content before sulfurization) : 7% by weight, Co content: 0.9% by weight, carrier: γ-Al ₂ O ₃ , 60-80 mesh) 50 mg, and after shaking for 30 minutes, the mercury in the solution was analyzed. It was 630 ppb. As a result, it was found that most of the mercury in the natural gas condensate was in the form of organic mercury or ionic mercury that was not adsorbed by the adsorbent.

[0015]

Example 1 SUS30 having a length of 200 mm and an inner diameter of 8 mm
Using a device in which a heating tube made of No. 4 was filled with SUS balls having a diameter of 2 mm to a height of 80 mm, the mercury used in Comparative Example 1 was added to 80
Natural gas condensate containing 0 ppb (μg / l) was preheated and introduced at a constant flow rate of 0.6 ml / min onto the upper surface of the heating tube packed bed kept at a predetermined temperature. At this time, nitrogen gas, which is an inert gas, was used as a carrier at an upflow rate of 2.3 ml / min. The heavy components were extracted from the lower part of the heating tube as liquid. Inner diameter 8 on the downstream side of the heating tube
A SUS304 adsorption tube of mm was provided and 1.4 g of the adsorbent was filled. The adsorbent was a pre-sulfurized Co-Mo adsorbent (Mo content before sulfurization: 7.0%, Co content: 0.9
%, Carrier: γ-Al ₂ O ₃ , 60 to 80 mesh) was used. The heating temperature was the same as or slightly higher than that of the heating tube. All the connecting pipes of the heating pipe and the adsorption pipe were kept at the same temperature as that of the heating pipe to prevent the evaporation liquid from condensing. The gaseous component flowing out from the upper part of the heating tube is introduced into the adsorption tube and brought into contact with the adsorbent.The adsorption tube outlet gas is air-cooled and then passed through the gas-liquid separator, and the distillate separated by the gas-liquid separator The results of mercury analysis of the outgassing are shown in Table 1. It can be seen from Table 1 that the mercury in the natural gas condensate can be effectively removed by the adsorbent by performing the heat treatment. Especially 220
It is completely removed below ℃. At 250 ° C or higher, a small amount of mercury flows out, but this is because mist that is not sufficiently heated is entrained in the carrier gas from the upper part of the heating tube, and as a result, mercury that is difficult to adsorb remains, or the adsorbent Therefore, it is considered that some of the mercury was released.

[Table 1]

[0016]

Comparative Example 2 A heat treatment test was conducted under the same conditions as in Example 1 except that the adsorption tube was not used. Table 2 shows the mercury analysis results of the distillate and the distillate gas separated by the gas-liquid separator. The amount of mercury contained in the raw material natural gas condensate is 4.8μ.
Since it is g (6 ml x 800 ppb), it is 4 on the gas side.
It can be seen that 8 to 73% of mercury is flowing out. Most of this mercury is changed to elemental mercury and is adsorbed by the adsorbent as in Example 1.

[Table 2]

[0017]

Example 2 A natural gas condensate containing 167 ppb (μg / l) of total mercury was heat-treated and evaporated in the same manner as in Example 1. Condensate flow rate is 0.6m
The flow rate of the carrier gas was set at 1 / min and the carrier gas flow rate was set at 2.3 ml / min.
A pre-sulfurized Co-Mo-based adsorbent (Mo content before sulfuration: 7.0%, Co content: 0.9%, carrier:
γ-Al ₂ O _3, 60 to 80 mesh) was 1.5g filled. The heating temperature of the heating tube and the adsorption tube was set to 240 ° C. Table 3 shows the mercury analysis results of the distillate and the distillate gas separated by the gas-liquid separator at this time.

[0018]

Example 3 A pre-sulfurized Ni-Mo adsorbent as an adsorbent (Mo content before sulfurization: 6.9%, Ni content:
The same test as in Example 2 was conducted except that 1.5 g of 1.2%, carrier: γ-Al ₂ O ₃ , 60 to 80 mesh) was used. Table 3 shows the mercury analysis results of the distillate and the distillate gas separated by the gas-liquid separator at this time.

[0019]

Example 4 Pre-sulfidized Ni-Co-M as adsorbent
o-based adsorbent (Mo content before sulfurization: 6.7%, Co content: 0.9%, Ni content: 0.5%, carrier: γ-Al
₂ O ₃ , 60 to 80 mesh) The same test as in Example 2 was performed except that 1.5 g was used. Table 3 shows the mercury analysis results of the distillate and the distillate gas separated by the gas-liquid separator at this time.
It was shown to.

[0020]

Comparative Example 3 The same test as in Example 2 was conducted without filling the adsorbent tube with the adsorbent. Table 3 shows the mercury analysis results of the distillate and the distillate gas separated by the gas-liquid separator at this time.

According to Table 3, when a liquid hydrocarbon containing mercury is heat-treated at a temperature of 90 ° C. or higher to be evaporated, and the obtained gaseous component is brought into contact with an adsorbent containing a heavy metal sulfide in a gaseous state. , it is understood to be a removal rate of mercury than 96 percent versus the raw condensate is evaporated gas side. However, when no adsorbent was used (Comparative Example 3), 72% of the mercury in the condensate flowed out to the gas side.

[Table 3]

[0022]

Example 5 Natural gas condensate containing almost no mercury (initial boiling point: 35 ° C., 50% distillation temperature: 134.5)
C., final boiling point 367 ° C.), diisopropyl mercaptomercury was added to prepare a model solution having a mercury concentration of 950 ppb (μg / l). This liquid was passed through a glass column (inner diameter 4 mm) filled with a molecular sieve 3A having a diameter of 0.3 to 0.5 mm and having a length of 30 cm with a metering pump at a flow rate of 2 ml / min. At this time, the pressure was kept at normal pressure, and the heating temperatures were 90 ° C, 130 ° C, and 160 ° C. Distillation rate of gaseous components at each temperature is 25%, 44%,
At 55%, it was almost in line with the boiling point distribution. When these gaseous components were treated as they were in the same manner as in Example 1 using the same adsorbent used in Example 4, as a result, neither distillate nor distillate gas was mercury-distilled at all and 100% was removed. Was there.

[0023]

[Comparative Example 4] A heat treatment test was conducted under the same conditions as in Example 5 except that an adsorption tube was not used, and the temperature was 90 ° C, 130 ° C, 160 ° C.
At that temperature, the gaseous components that flowed out were cooled and liquefied, and mercury was analyzed. They were 90, 138, and 2, respectively.
It was 19 ppb (μg / l), but most of it was elemental mercury, which was adsorbed and removed by an adsorbent containing a heavy metal sulfide as in Example 5.

[0024]

Effect of the Invention The process can be simplified. 2. Equipment costs can be reduced. 3. No post processing is required. 4. Heavy components can be cut simultaneously with mercury removal.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C10G 29/10 6958-4H // B01D 53/64 B01J 20/02 A 7202-4G

Claims (3)

[Claims] 1. A liquid hydrocarbon containing mercury is heat-treated at a temperature of 90 ° C. or higher to be evaporated, and the obtained gaseous component is brought into contact with an adsorbent containing a heavy metal sulfide in a gaseous state. Method for removing mercury in liquid hydrocarbons. 2. The method for removing mercury in liquid hydrocarbons according to claim 1, wherein the adsorbent is mainly composed of molybdenum sulfide. 3. The molybdenum sulfide-based adsorbent is a Mo—Co based sulfide, a Mo—Ni based sulfide, or a Mo—
The method for removing mercury from liquid hydrocarbons according to claim 2, wherein the Ni-Co sulfide is supported on a carrier.