JPH0570780A - Depth desulfurization of middle-or low-boiling oil - Google Patents

Abstract

PURPOSE:To provide a method of efficient depth desulfurization of a middle- or low-boiling oil, performed as pretreatment for generating hydrogen by the steam reforming of a middle- or low-boiling oil, such as naphtha or kerosine. CONSTITUTION:A middle- or low-boiling oil is desulfurized in a fixed bed reactor at a temperature of 200-380 deg.C, an LHSV of 0.2-2h<-1>, and a pressure of 3-10kg/cm<2> G by using a catalyst comprising ZnO carrying Ni or NiO so that the sulfur content can be reduced to about 0.5wt.ppm or lower, or about 0.2wt. ppm or lower even when hydrogen gas not of high purity but of relatively low purity and containing carbon dioxide gas is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep desulfurization method for medium and light oils such as naphtha and kerosene, and particularly as a pretreatment step when hydrogen is generated by steam reforming of these medium and light oils. The present invention relates to a deep desulfurization method for raw materials (medium and light oil).

[0002]

2. Description of the Related Art Hydrogen used in fuel cell systems,
When obtained by steam reforming of medium-light oils such as naphtha and kerosene, the sulfur content in the raw material composed of these medium-light oils is about 0.5 wtppm or less, preferably about 0, for the purpose of protecting the steam reforming catalyst. It is necessary to desulfurize to less than 0.2 wtppm. Conventionally, a typical desulfurization method performed prior to the steam reforming of the above-mentioned raw material is Ni-Mo system or Co-M.
In the presence of o-based catalyst, in a hydrogen stream, about 350-400 ℃,
It is a hydrodesulfurization method in which organic sulfur in a raw material is hydrolyzed at a pressure of about 15 to 30 kg / cm ² G and then H ₂ S produced is adsorbed and removed by ZnO. The hydrogen gas used in this method generally has a high hydrogen purity and a purity of about 95%.
% Or more of hydrogen is used, and it is indispensable to use high-purity hydrogen in order to reduce the sulfur content in the raw material.

[0003]

Generally, in a hydrogen production apparatus, a decarbonation step or the like is installed after a steam reforming step in order to remove CO and CO ₂ contained in a produced gas to improve hydrogen purity. It is possible to maintain the hydrogen purity at about 95% or more. In addition, by circulating a part of this high-purity hydrogen and using it in the desulfurization step of the raw material composed of medium-light oil such as naphtha and kerosene, the total sulfur concentration in the raw material is about 0.5 wtppm. It is possible to:

By the way, in order to obtain hydrogen used in the above-mentioned fuel cell system or the like from a medium or light oil such as naphtha or kerosene as a raw material, the device is downsized and safety measures are required.
It is required that hydrogen can be efficiently obtained under the condition of low pressure. In order to reduce the size of the device in response to this demand, the above decarbonation step is not necessary, and the pressure after the pressure is 10 kg / cm ² G or less, and the gas after steam reforming is used instead of high-purity hydrogen. the CO contained converted to CO _2, by using the hydrogen gas containing the CO _2, about the sulfur content in the raw material 0.5w
It is possible to desulfurize by about tppm or less. However, in the above-mentioned conventional method for desulfurizing medium and light oils, if CO ₂ is contained in the hydrogen gas used, the desulfurization efficiency decreases,
It was difficult to reduce the sulfur content in the feedstock to a predetermined amount.

The present invention has been achieved in view of the above aspects, the following conditions of low pressure 10 kg / cm ² G, be a hydrogen gas containing CO _2, naphtha,
It is an object of the present invention to provide a deep desulfurization method capable of reducing the sulfur concentration of medium and light oils such as kerosene to 0.5 wtppm or less.

[0006]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that a hydrogen gas containing CO ₂ is used under a certain reaction condition using a specific catalyst. The inventors have found a method capable of efficiently removing the sulfur content in the raw material to a low concentration even by using, and have completed the present invention.

That is, according to the present invention, in a method for desulfurizing medium and light oils using a fixed bed reaction tower, a catalyst in which Ni or NiO is supported on ZnO in the presence of hydrogen gas containing carbon dioxide is used, and a temperature of 200 is used. ˜380 ° C., LHSV0.
The method is desulfurization under the conditions of ^{2 to 2} h ⁻¹ and a pressure of 3 to 10 kg / cm ² G.

The present invention will be described in detail below. ZnO used in the present invention is an inorganic zinc salt such as zinc borate, basic zinc or zinc nitrate, or an organic zinc such as zinc benzoate, zinc lactate, zinc citrate or zinc acetate, which is decomposed by heating, or a metal. It can be produced by firing zinc in air. In addition, Ni or Ni used in the present invention
Examples of the O (hereinafter simply referred to as Ni) source include various salts of Ni, such as nitrates, acetates, and chlorides.

As a method for supporting Ni on ZnO, known methods such as an impregnation method and a coprecipitation method can be used.
To give a concrete example, Zn
Ni can be supported on O. In the impregnation method, first,
A predetermined amount of ZnO is weighed, and water is gradually added to the inside of the ZnO while stirring to absorb the water. This water absorption is preferably performed until the inside of ZnO is saturated, and the necessary amount of Ni is calculated from this saturated water content and known ZnO. Next, an aqueous solution of the above Ni salt adjusted to an appropriate concentration based on the amount of Ni is gradually added dropwise to the weighed predetermined amount of ZnO while stirring to allow saturated water absorption, as in the case of the above water. It may be dried and baked. In the coprecipitation method, an alkaline aqueous solution is added to a mixture of an aqueous solution of Zn nitrate, acetate, etc. and an aqueous solution of Ni nitrate, acetate, etc. to form a precipitate, which is filtered and washed, It may be dried and baked. In the above impregnation method, if it is desired to increase the amount of Ni supported, the above impregnation operation may be repeated.

The amount of Ni supported on ZnO is about 1 wt% or more with respect to ZnO as NiO, preferably about 5 to 5
It is 0 wt%. If it is less than about 1 wt%, the effect of desulfurization by supporting Ni on ZnO is small, and about 50 wt%
Even if it is more, the effect will be saturated and the effect over the supported amount cannot be obtained. The above catalyst in which Ni is supported on ZnO is
In the present invention, it is used in the presence of hydrogen, but it is preferable to reduce it in advance in order to exert more activity.

The raw material which can be used in the present invention is naphtha containing about 1 to 150 ppm of sulfur,
Mainly medium to light oils such as kerosene, but it goes without saying that butane, LPG and the like, which are lighter than these raw materials, can also be used.

Further, in the desulfurization method of the present invention, the steam reforming furnace outlet gas or the gas which has undergone the subsequent CO conversion step, more specifically, the gas containing CO _{2 and} having a hydrogen purity of about 75%. Can be used as a circulating gas in the raw material desulfurization step, and the sulfur content in the raw material is about 0.5 wtppm or less and, if necessary, about 0.2 wtppm or less, by setting the range of predetermined reaction conditions. It is characterized in that it can be desulfurized up to the present and has a long catalyst life.

In the present invention, the above-mentioned catalyst is packed in a fixed bed reaction column and the temperature is about 200 to 380 ° C., preferably about 280 to 350 ° C., and LHSV is about 0.2 to 2 h ⁻¹ , preferably about 0. 5 ~ 1.5h ^-1 , pressure about 3 ~ 10kg
By the range of / cm ² G, hydrogen purity of about 75
Even by using a gas containing about ₂ % of CO ₂ , the sulfur content in the raw material can be desulfurized to about 0.5 wtppm or less. When the reaction temperature is less than about 200 ° C., the LHSV is faster than about 2 h ⁻¹ , or the pressure is less than about 3 kg / cm ² G, the concentration of sulfur in the raw material should be about 0.5 wtppm or less. If not possible and the reaction temperature is higher than about 380 ° C, LHSV is about 0.2.
If less than h ^-1 , or the pressure is about 10 kg / cm ² G
If it is higher, it is not preferable in terms of catalyst life.

[0014]

According to the present invention, the catalyst in which Ni or NiO is supported on ZnO is used in the presence of hydrogen gas containing CO ₂ and not so high in purity at a specific temperature, LHSV, and pressure conditions to produce a medium or light oil. , Sulfur content of about 0.5 wtppm, or up to about 0.2 wtppm or less, performs a deep desulfurization action. In this deep desulfurization, the presence of Ni in the catalyst promotes the desulfurization reaction of the medium and light oils, and the H ₂ S produced thereby is adsorbed and removed by ZnO which is the carrier of the catalyst. is there.

[0015]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to these. Example 1 (Preparation of catalyst used) 9.4 NiO to ZnO
A catalyst loaded with wt% was prepared. The preparation method was as follows. Water was slowly added dropwise to a predetermined amount of ZnO while stirring using a buret, and the addition was continued until the inner surface of the container containing ZnO was slightly wetted, and the saturated water content of ZnO was measured in advance. .33 ml / g-ZnO
Met. Based on this _{value, Ni (NO 3) 2 ·} 6H 2 O
12.3 g of Ni was dissolved in 10 ml of water to prepare a Ni-containing aqueous solution, and the same operation as described above was performed.
The i-containing aqueous solution was impregnated. After impregnation, dry firing is performed,
The first loading was completed. Next, the second operation was performed on the ZnO after the first operation of supporting Ni was carried out by the same operation as described above, and finally, as NiO, with respect to ZnO.
A catalyst supporting 4 wt% was obtained. In the above operation, firing was performed in air at a temperature of 500 ° C.

(Desulfurization reaction) A catalyst having 9.4 wt% of NiO obtained above supported on ZnO was charged into a predetermined reaction tube of 6 cc, and kerosene having the properties shown in Table 1 was used as a raw material for H ₂ and CO. ₂ mixed gas (H ₂ : 75 vol%, CO
_2: the presence of 25vol%), _{H 2} / kerosene volume ratio = 30
0, reaction pressure 5 kg / cm ² G, reaction temperature 325 ° C., L
The desulfurization reaction was performed under the condition of HSV 1.0h ^-1 . The reaction tube has a diameter of 9.52 mm and a length of 2
The thing of 00 mm was used. As a result, the total sulfur content of the kerosene after desulfurization was 0.2 wtppm.

[0017]

[Table 1]

[0018] Example 2 in place of _{Ni (NO 3) 2 · 6H} 2 O aqueous solution used in Example _{1, Ni (CH 3 COO)} 2 · 4H 2 O 10.
Example 1 using an aqueous solution of 5 g dissolved in 10 ml of water
By performing the same operation as above, a catalyst supporting 9.6 wt% of ZnO as NiO was obtained. Using this catalyst, a desulfurization reaction was carried out in the same manner as in Example 1, and as a result, the total sulfur content of the kerosene after desulfurization was 0.2 wtppm.

Example 3 30 g of zinc acetate and 5 g of nickel nitrate were dissolved in water to prepare a mixed solution of both, and ammonium carbonate 22 was added to this solution.
An aqueous solution of ammonium carbonate dissolved in 200 ml of water and 15% aqueous ammonia were added to the mixture to form a precipitate of zinc carbonate and basic nickel carbonate, and the mixture was allowed to stand for about 12 hours. The precipitate was filtered, washed with water, dried and calcined to prepare a catalyst.
The firing is performed in air at 500 ° C. for 10 hours, and the NiO Z
A catalyst having a loading amount of 10.0 wt% on nO was obtained. Using this catalyst, a desulfurization reaction was performed in the same manner as in Example 1, and as a result, the total sulfur content of the kerosene after desulfurization was 0.1 wtpp.
It was m.

[0020] the same manner as in Example 4 Example _{1, Ni (NO 3) 2} · 6H
An aqueous solution prepared by dissolving 6.6 g of ₂ O in 10 ml of water was used to obtain a catalyst supporting 5.1 wt% of ZnO as NiO. As a result of carrying out a desulfurization reaction by the same operation as in Example 1 using this catalyst, the total sulfur content of the kerosene after desulfurization was 0.2 wtppm.

[0021] the same manner as in Example 5 Example _{1, Ni (NO 3) 2} · 6H
Using an aqueous solution of 23.2 g of ₂ O dissolved in 10 ml of water, a catalyst supporting 21.1 wt% with respect to ZnO as NiO was obtained. In this case, the impregnation operation was performed 3 times. Moreover, after filling the reaction tube with the above catalyst, the pressure is 9.0 kg.
/ Cm ² G, temperature 390 ° C., pure hydrogen flow rate 60 ml /
The mixture was subjected to a reduction treatment for 21 hours, and then subjected to a desulfurization reaction. Desulfurization was performed under the same conditions as in Example 1, and as a result, the total sulfur content after desulfurization was 0.1 wtppm or less.

Example 6 Using the catalyst used in Example 3 and a commercially available catalyst for comparison, a catalyst life evaluation test was conducted under the same reaction conditions as in Example 1. The commercially available catalyst is NiO 77.5 wt.
%, Al ₂ O ₃ 12.0 wt%, SiO ₂ 9.0 wt
%, CaO 1.5 wt% composition was used. The above results are shown in Table 2.

[0023]

[Table 2]

[0024]

EFFECTS OF THE INVENTION The present invention, when hydrogen used in a fuel cell system or the like is produced from a light and medium-sized light oil such as kerosene as a raw material, the desulfurization step of the raw material is performed at about 10 kg.
/ Cm ² G, and even in the presence of hydrogen gas containing CO ₂ , it is possible to achieve a considerably high depth of desulfurization,
It has a long catalyst life and is of extremely high industrial value.

Claims (1)

[Claims] 1. A method for desulfurizing medium and light oils using a fixed bed reactor, using a catalyst in which Ni or NiO is supported on ZnO in the presence of hydrogen gas containing carbon dioxide, at a temperature of 200 to 380 ° C. , LHSV 0.2-2
A deep desulfurization method for medium and light oils, which comprises desulfurizing under conditions of h ⁻¹ and a pressure of 3 to 10 kg / cm ² G.