JP4065590B2 - Adsorption and removal method of thiophene sulfur compounds - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of adsorbing and removing a thiophene-based sulfur compound contained in a specific hydrocarbon oil using a nickel-based adsorbent pretreated by a special method. The present invention relates to a method for efficiently adsorbing and removing a thiophene-based sulfur compound using a nickel-based adsorbent which has been ineffective with respect to the compound and has been subjected to reduction treatment and stabilization treatment.
[0002]
[Prior art]
Various petroleum compounds produced in the petroleum refining process contain various sulfur compounds. The most common removal of these sulfur compounds is hydrodesulfurization treatment. However, the hydrodesulfurization treatment has a problem that the apparatus is large and it is difficult to completely remove the sulfur compound 100%. For example, the sulfur content standard of benzene used as a petrochemical feedstock is often set to 1 wtppm or less, and when producing benzene feedstock oil in a petroleum refining process, it is necessary to remove the sulfur content almost completely. is there.
[0003]
Adsorption desulfurization is used together with hydrodesulfurization as a method of removing sulfur compounds contained in hydrocarbons. This is a method in which hydrocarbon oil is brought into contact with an adsorbent that selectively adsorbs a sulfur compound to adsorb and remove the sulfur compound. Advantages of adsorptive desulfurization include that the desulfurization rate is almost 100%, and that it can be performed at a lower temperature and lower pressure than hydrodesulfurization. On the other hand, as a disadvantage of adsorptive desulfurization, since only a certain amount of sulfur compound can be adsorbed on the adsorbent, there is a problem that when the concentration of the sulfur compound is high, the frequency of replacement of the adsorbent becomes high and the operation cost increases. Therefore, the adsorption desulfurization is generally used when the sulfur compound concentration is as small as several tens of wtppm or less. When the sulfur compound concentration is higher than this, the adsorption desulfurization is performed after hydrodesulfurization treatment in advance. It is desirable to do.
[0004]
As an adsorbent used for adsorptive desulfurization, those containing zinc, copper, nickel or the like as a main component are used. Of these, only nickel-based adsorbents exhibit adsorption capacity for organic sulfur compounds such as thiols, sulfides, and thiophenes other than hydrogen sulfide. It is shown in US Pat. No. 4,446,005 that a nickel-based adsorbent is effective for adsorption of sulfur compounds. As the nickel-based adsorbent, nickel oxide formed by using alumina or the like as a binder and having a nickel content of 30 to 70% is used. In use, it is used after hydrogen reduction at a temperature of about 300 to 600 ° C. When actually used industrially, it is practically impossible to perform the reduction treatment in the adsorption tower because the reduction temperature is high.
[0005]
Therefore, in the adsorbent manufacturer, the adsorbent is reduced with hydrogen in a reducing furnace in the adsorbent manufacturing factory, cooled to room temperature, and then adsorbed with oxygen (air) or carbon dioxide, etc. Stabilized to prevent ignition and supplied to users. The user fills an adsorption tower with an adsorbent that has been subjected to reduction treatment and stabilization treatment, and feeds the raw material oil at 150 to 250 ° C. for use.
[0006]
As described above, the situation is that most commercially available nickel-based adsorbents are supplied and used in a form subjected to a stabilization treatment after the reduction treatment. The nickel-based adsorbent thus stabilized after the reduction treatment is installed, for example, between the hydrodesulfurization device and the reformer of naphtha as a raw material in a catalytic reformer that produces high-octane gasoline. It is packed in an adsorption tower and is used for adsorption removal of hydrogen sulfide, thiol, and the like.
[0007]
[Problems to be solved by the invention]
However, the nickel-based adsorbent that has been stabilized after the reduction treatment has a problem in that it exhibits a high adsorption ability for thiols and sulfides, but hardly exhibits an adsorption ability for thiophene-based sulfur compounds. The thiophene-based sulfur compound referred to here is thiophene, alkylthiophene, benzothiophene, or alkylbenzothiophene. It has been conventionally known that a nickel-based adsorbent that is subjected only to a reduction treatment at a high temperature of 300 to 600 ° C. and is not stabilized has an adsorption ability for a thiophene-based sulfur compound. However, since the construction cost of an adsorption tower designed to reduce the filler with hydrogen at a high temperature is enormous, the present inventors do not know an example of actually performing adsorption desulfurization of a thiophene-based sulfur compound.
[0008]
The object of the present invention is to solve the above-mentioned conventional problems and to use an ordinary adsorption tower having a heating facility up to about 200 ° C. to enable adsorptive desulfurization of a thiophene-based sulfur compound with a nickel-based adsorbent. is there.
[0009]
[Means for Solving the Problems]
As a result of diligent research to solve the above-mentioned problems, the inventors of the present invention carried out a pretreatment under special conditions after filling the adsorption column with a nickel-based adsorbent that has been subjected to stabilization treatment after hydrogen reduction treatment. The present invention has been completed by finding a method for adsorptive desulfurization of a sulfur compound.
[0010]
That is, the said subject is achieved by the following invention.
1. When the thiophene sulfur compound contained in the hydrocarbon oil having a boiling point of 20 to 250 ° C. is adsorbed and removed using a nickel adsorbent having a nickel content of 30 wt% or more, the adsorbent is hydrogen reduced at 300 to 600 ° C., With respect to the stabilized nickel-based adsorbent obtained by aeration of oxygen or carbon dioxide at 100 ° C. or lower after cooling to room temperature, 5 to 4 light hydrocarbons having 2 to 4 carbon atoms substantially free of olefins are contained. A method of adsorbing and removing a thiophene-based sulfur compound, comprising aerating a gas containing 30 vol% and 60 to 90 vol% hydrogen at a temperature of 170 to 220 ° C and a pressure of 2 MPa or less to deposit carbon on the adsorbent.
2. When adsorbing and removing a thiophene sulfur compound contained in a hydrocarbon oil having a boiling point of 20 to 250 ° C. and an aromatic hydrocarbon ratio of 20 vol% or more using a nickel adsorbent having a nickel content of 30 wt% or more, A method for adsorbing and removing a thiophene-based sulfur compound, which is characterized by following the procedures (1) to (3).
[0011]
(1) The adsorbent is reduced with hydrogen at 300 to 600 ° C., cooled to room temperature, and then oxygen or carbon dioxide is aerated at 100 ° C. or lower to stabilize the catalyst.
[0012]
(2) The nickel-based adsorbent treated in (1) is packed in an adsorption tower and contains 5 to 30 vol% of light hydrocarbons having 2 to 4 carbon atoms substantially free of olefins and 60 to 90 vol% of hydrogen. Gas is passed through the adsorbent at a temperature of 170 to 220 ° C. and a pressure of 2 MPa or less to deposit 0.05 to 5.0 wt% of carbon on the adsorbent.
[0013]
(3) A hydrocarbon oil having a boiling point of 20 to 250 ° C. and a ratio of aromatic hydrocarbons of 20 vol% or more is brought into contact with the adsorbent at a temperature of 170 to 220 ° C. in a substantially hydrogen-free state. The adsorbed thiophene sulfur compound is removed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In order to start the research for enabling the adsorption and desulfurization of a thiophene-based sulfur compound with a nickel-based adsorbent that has not been put into practical use, the present inventors firstly stabilized adsorption after reduction treatment at a high temperature of 300 to 600 ° C. The reason why the agent did not show adsorption capacity for thiophene sulfur compounds was investigated. As a result, it was found that the active sites on the surface of the catalyst on which oxygen or carbon dioxide was adsorbed for the stabilization treatment contributed to the adsorption of the thiophene sulfur compound, and the adsorption active sites disappeared by the stabilization treatment. It was. Next, the removal of the oxygen or carbon dioxide adsorption and the examination of the treatment capable of adsorbing the thiophene-based sulfur compound were conducted. When the stabilization treatment was conducted at 100 ° C. or lower, the temperature was as low as 170 ° C. or higher. The inventors have found that the adsorption of oxygen or carbon dioxide can be removed by hydrogen treatment, and have found a clue that reaches the present invention.
[0015]
Surprisingly, when the stabilization treatment is performed at 100 ° C. or higher, the adsorption ability is not exhibited unless the reactivation is performed at a high temperature of 300 to 600 ° C. like the adsorbent in the oxide state. It is a completely new finding that an adsorbent that has been subjected to a reduction treatment and stabilized with oxygen or carbon dioxide at 100 ° C. or lower can recover its activity by a relatively low temperature hydrogen treatment at 170 ° C. or higher. It was presumed that the nickel structure in the oxidation state of the stabilization treatment was different.
[0016]
As the inventors proceeded with further research, when the adsorption tower was filled with the adsorbent that had been stabilized after the reduction treatment, and further used for the hydrogen treatment, the adsorption tower was treated with an inert gas for a considerably long time after the hydrogen treatment. We paid attention to the fact that even when the inside was replaced, heat was generated when oil was passed through the feedstock containing thiophene sulfur compounds. As a result of the investigation, it was clarified that the cause of the heat generation was due to the heat of adsorption and the hydrogenation reaction of aromatic hydrocarbons. Is also a big problem.
[0017]
Therefore, as a result of intensive studies, the inventors of the present invention have developed a gas containing 5 to 30 vol% of light hydrocarbons having 2 to 4 carbon atoms substantially free of olefins and 60 to 90 vol% of hydrogen at a temperature of 170 to 220. When air is passed through the adsorbent at ℃ and pressure of 2 MPa or less, and 0.05 to 5.0 wt% of carbon is deposited on the adsorbent, heat generation when the raw material oil is passed is suppressed, and the adsorption capacity is reduced. The epoch-making method of having little influence was found, and the present invention was completed.
[0018]
The present invention will be described in more detail. Regarding the boiling point of the feedstock, a so-called gasoline fraction of 20 to 250 ° C. can be applied. Although it may contain a fraction of less than 20 ° C, it is more efficient to adsorb in the liquid phase from the viewpoint of the adsorbent life and the size of the apparatus, and the light fraction less than 20 ° C is not much. It is preferable not to include it. Moreover, although the adsorbing desulfurization of the present invention can be carried out even if some fractions exceeding 250 ° C. are contained, heavy aromatic hydrocarbons are contained in the fractions exceeding 250 ° C. It is preferable that the agent is not contained because the life of the agent is shortened.
[0019]
The present invention can be applied to a hydrocarbon oil having an aromatic hydrocarbon ratio of 20 vol% or more. Even if the ratio of aromatic hydrocarbons is less than 20 vol%, there is no problem in achieving the adsorptive desulfurization by applying the present invention. However, when the ratio of aromatic hydrocarbons is less than 20 vol%, Since the degree of heat generation due to hydrogenation is small, it becomes difficult to utilize 0.05 to 5.0 wt% of carbon, which is a feature of the present invention, to suppress the hydrogenation reaction. Among sulfur compounds contained in hydrocarbons, those that can be adsorbed include alkylthiophenes such as thiophene, methylthiophene, dimethylthiophene, and ethylthiophene, and alkyldibenzothiophenes such as dibenzothiophene and methyldibenzothiophene, as well as thiols. And sulfides. Dissolved hydrogen sulfide can also be removed by adsorption.
[0020]
Although there is no restriction | limiting in particular as a nickel type adsorption agent, The general commercial item which shape | molded nickel oxide with binders, such as a silica and an alumina, can be used. A carrier having nickel supported thereon can also be used. The nickel content is preferably 30 wt% or more in consideration of the efficiency of the adsorption tower.
[0021]
These adsorbents need to be reduced with hydrogen in advance before being packed in the adsorption tower and then stabilized. Hydrogen reduction is performed by bringing hydrogen gas into contact with the adsorbent in the range of 300 to 600 ° C. A higher reduction rate is better, but about 50% can be used sufficiently.
[0022]
The progress of the reduction reaction can be performed while observing the production of water. After the reduction, the temperature of the adsorbent is cooled, and oxygen or carbon dioxide is passed through to stabilize the adsorbent. The purpose of the stabilization treatment is to facilitate the handling by adsorbing oxygen or carbon dioxide on the surface of the adsorbent, and if there is no stabilization treatment, there is even a risk of ignition by a rapid oxidation reaction. As a procedure for venting oxygen or carbon dioxide, first, hydrogen is purged with an inert gas such as nitrogen, and then oxygen or carbon dioxide diluted with an inert gas such as nitrogen is gradually vented. At this time, it is necessary to control the dilution rate and ventilation rate of oxygen or carbon dioxide so that the temperature of the adsorbent is 100 ° C. or lower. The aeration temperature is preferably as low as possible. If the temperature exceeds 100 ° C., the adsorption capacity for thiophene is lost, and the adsorption capacity is not recovered even by hydrogen treatment after filling the adsorption tower.
[0023]
The adsorbent subjected to the reduction and stabilization treatment is used by being packed in a packed tower. When filling, care must be taken to avoid powdering. It can be applied to both up-flow and down-flow adsorption towers.
[0024]
Since the adsorbent subjected to the stabilization treatment does not exhibit adsorption ability for thiophene as it is, it is necessary to perform reactivation treatment with hydrogen in the present invention. Moreover, in this invention, it has the characteristics to precipitate carbon simultaneously with reactivation. Specifically, with respect to the adsorbent packed in the adsorption tower, a gas containing 5 to 30 vol% light hydrocarbons having 2 to 4 carbon atoms substantially free of olefins and 60 to 90 vol% hydrogen is added to the temperature. The adsorbent is aerated at 170 to 220 ° C. and a pressure of 2 MPa or less to deposit 0.05 to 5.0 wt% of carbon on the adsorbent. This hydrocarbon-containing gas may be prepared, but reformer hydrogen produced from a refinery catalytic reformer (reformer) can be used as it is. Since reformer hydrogen usually contains light hydrocarbons, it can be used as it is if it is within the composition range of the present invention by analysis, and if it is outside the range, it is adjusted to be a composition within the range. it can. If the temperature is less than 170 ° C., the adsorption ability of thiophene hardly appears, and if it exceeds 220 ° C., coking becomes remarkable and affects the total adsorption amount. The pressure is preferably as low as possible, but if the pressure exceeds 2 MPa, heat generation due to hydrocracking of the light hydrocarbons contained is significant, which may hinder temperature control.
[0025]
The adsorbent thus pretreated is a hydrocarbon oil having a boiling point of 20 to 250 ° C. and a ratio of aromatic hydrocarbons of 20 vol% or more in a liquid phase without hydrogen, and becomes an adsorbent at a temperature of 170 to 220 ° C. By contacting, the contained thiophene sulfur compound can be adsorbed and removed. When the temperature is lower than 170 ° C., the adsorption capacity is remarkably reduced, and when the temperature exceeds 220 ° C., coking is promoted and the adsorption capacity is remarkably lowered. The optimum temperature is 180-220 ° C. Although there is no restriction | limiting in oil transmission speed, 3 / hr or less is preferable at LHSV because an adsorbent can be utilized efficiently. The adsorption capacity for thiophene is usually about 0.2 to 1.0 wt% sulfur weight / nickel weight, and alkylthiophene with many alkyl substituents has a small saturated total adsorption amount. Since regeneration of the adsorbent requires firing at a temperature of 600 ° C. or higher, it is common to use a new adsorbent without filling it.
[0026]
【Example】
The embodiment of the present invention will be described in more detail by way of examples. As the adsorbent, nickel oxide powder formed with silica and an alumina binder was used. The composition is 65 wt% NiO, 25 wt% silica, and 10 wt% alumina, and is a 1/16 inch extruded product.
[0027]
100 g of the adsorbent was filled in a normal pressure flow-type firing tube having an inner diameter of 1 inch, and 50 ml of hydrogen was bubbled at a normal pressure to raise the temperature to 500 ° C. The nickel was reduced by holding at 500 ° C. for 2 hours. The firing tube was cooled to room temperature while bubbling hydrogen and purged with nitrogen.
[0028]
As a treatment for stabilizing the adsorbent, a gas having an oxygen concentration of 0.5 vol%, 2 vol%, 5 vol%, 10 vol% (diluted with nitrogen) was aerated at a rate of 50 ml per minute for 30 minutes each.
[0029]
Example 1
20 g of an adsorbent was filled in an upflow type 3/4 inch adsorption tube having a pressurizing function. Hydrogen gas containing light hydrocarbons (composition: hydrogen 80vol%, methane 10vol%, ethane 7vol%, propane 3vol%) was aerated at a rate of 0.8MPa, 50ml / min, up to 180 ° C at a rate of 2 ° C / min. The temperature was raised, followed by aeration at 180 ° C. for 24 hours. After the treatment, the temperature is cooled to room temperature and toluene is added to LHSV.
The temperature was raised again to 180 ° C. at a rate of 5 ° C. per minute while passing oil at 1 / hr. After reaching 180 ° C., the adsorption ability was measured by passing through a toluene solution containing 30 wtppm of thiophene as a sulfur content instead of toluene. Sulfur content was not detected in the spilled oil until 122 hours after the start of oil passing, and the sulfur content in the spilled oil exceeded 1.0 wtppm at 330 hours. The adsorbent adsorption capacity up to 330 hours was 1.3 wt% -S / g-adsorbent.
[0030]
In addition, it was 0.3 wt% when the carbon deposition amount on the adsorption agent after the hydrogen gas process containing a light hydrocarbon was measured separately.
[0031]
Example 2
In the same manner as in Example 1, a toluene solution containing 30 wtppm of 2,5-dimethylthiophene as a sulfur content was passed through and the adsorption capacity was measured. Sulfur content was not detected in the spilled oil until 178 hours immediately after the start of oil passing, and the sulfur content in the spilled oil exceeded 1.0 wtppm at 190 hours. The adsorbent adsorption capacity up to 190 hours was 0.7 wt% -S / g-adsorbent.
[0032]
Comparative Example 1
The adsorbent that had been subjected to the stabilization treatment was filled in the same adsorption apparatus as in Example 1, and the adsorption experiment of thiophene was performed with the same operation and raw material oil (a toluene solution containing 30 wtppm of thiophene as a sulfur content). As a result, 18 wtppm of sulfur was detected in the spilled oil immediately after oil passing, and after 30 hours of oil passing, the sulfur concentration became 29 wtppm and almost no adsorption capacity was exhibited.
[0033]
【The invention's effect】
By using the nickel-based adsorbent subjected to the special pretreatment according to the present invention, the thiophene-based sulfur compound in the gasoline fraction can be adsorbed and desulfurized.

Claims (2)

When the thiophene sulfur compound contained in the hydrocarbon oil having a boiling point of 20 to 250 ° C. is adsorbed and removed using a nickel adsorbent having a nickel content of 30 wt% or more, the adsorbent is hydrogen reduced at 300 to 600 ° C., With respect to the stabilized nickel-based adsorbent obtained by aeration of oxygen or carbon dioxide at 100 ° C. or lower after cooling to room temperature, 5 to 5 light hydrocarbons having 2 to 4 carbon atoms that are substantially free of olefins. A method for adsorbing and removing a thiophene-based sulfur compound, characterized by depositing carbon on an adsorbent by aeration of a gas containing 30 vol% and 60 to 90 vol% of hydrogen at a temperature of 170 to 220 ° C and a pressure of 2 MPa or less. When adsorbing and removing a thiophene sulfur compound contained in a hydrocarbon oil having a boiling point of 20 to 250 ° C. and an aromatic hydrocarbon ratio of 20 vol% or more using a nickel adsorbent having a nickel content of 30 wt% or more, A method for adsorbing and removing a thiophene-based sulfur compound, which is characterized by following the procedures (1) to (3).
(1) The adsorbent is reduced with hydrogen at 300 to 600 ° C., cooled to room temperature, and then oxygen or carbon dioxide is aerated at 100 ° C. or lower to stabilize the catalyst.
(2) The nickel-based adsorbent treated in (1) is packed in an adsorption tower and contains 5 to 30 vol% of light hydrocarbons having 2 to 4 carbon atoms substantially free of olefins and 60 to 90 vol% of hydrogen. Gas is passed through the adsorbent at a temperature of 170 to 220 ° C. and a pressure of 2 MPa or less to deposit 0.05 to 5.0 wt% of carbon on the adsorbent.
(3) A hydrocarbon oil having a boiling point of 20 to 250 ° C. and a ratio of aromatic hydrocarbons of 20 vol% or more is brought into contact with the adsorbent at a temperature of 170 to 220 ° C. in a substantially hydrogen-free state. The adsorbed thiophene sulfur compound is removed.