JPS5939345A - Desulfurizing agent and preparation thereof - Google Patents

Abstract

PURPOSE:To make it possible to adsorb and remove sulfide in a dry system, by mixing iron oxide, titanium oxide and silicon oxide in a specific amount. CONSTITUTION:In forming an adsorbent enabled in efficient desulfurization in a wide temp. range, 40-95wt% iron oxide such as hematite or limonite, 5- 60wt% titanium oxide, 0-20wt% silicon oxide and, according to necessity, a molding aid are mixed to be molded. After the molded one is dried, it is baked at 300-600 deg.C for 1-10hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a desulfurization agent for dry adsorption and removal of sulfides contained in gas, and a method for producing the desulfurization agent.

In recent years, the effective use of coal has been considered in various fields due to the increase in energy demand and the shortage of petroleum energy sources. For example, coal can be converted into a medium to high calorie gas and used as fuel gas or an industrial raw material, or coal can be converted into a low calorie gas and used as a fuel for power generation in a combined cycle power generation system that combines gas starch and steam heat. is proposed.

However, for example, the combined gas produced by pressurized gasification of coal contains about 10,000 ppm of sulfides such as hydrogen sulfide, so the purpose is to prevent corrosion of equipment and air pollution caused by these. Conventionally, various desulfurization methods have been studied. In particular, in coal gasification power generation, in addition to preventing corrosion of the turbine and wheeler, from the point of view of energy efficiency, the approximately 10%
An important technical challenge is to minimize the volume loss of produced gases such as ~30% water vapor and approximately 10~30% carbon dioxide, maintain high temperatures, and utilize the sensible heat. , dry desulfurization is attracting attention.

On the other hand, in the field of oil, oil producing countries are taking measures to conserve light crude oil, and Japan is promoting multifaceted crude oil security policies to prevent imported crude oil from becoming heavier. The use of equal-heavy oil is being promoted. For this purpose, catalytic cracking of heavy oil is essential, and here, too, it is required to remove sulfides such as hydrogen sulfide from the cracked gas. Removal of hydrogen sulfide is also required.

Various desulfurizing agents have been used for this purpose, such as calcined dolomite, limestone, a mixture of molten alkali carbonate and limestone, copper oxide, zinc oxide,
Iron oxide etc. are known. However, calcium-based desulfurization agents have equipment problems such as the desulfurization rate decreases as the pressure increases, the calcium sulfide produced is toxic, and the reaction temperature requires a high temperature of 930°C. There is a problem in that alkali metal salt vapors scattered in the gas corrode equipment materials. On the other hand, copper oxide is expensive, and zinc oxide is difficult to desorb, that is, regenerate, the adsorbed sulfide.

In contrast, when iron oxide is used as a desulfurizing agent, as proposed in JP-A-53-37582'J,
A high desulfurization rate is maintained even at high temperatures of 400 to 600°C under pressure during coal gasification, and the regeneration can be performed at high temperatures of 500 to 800°C.
The waste heat can be effectively used in the steam cycle, increasing the efficiency of the combined cycle power generation system. However, although iron oxide has such excellent desulfurization properties, it has the problem of being easily abraded into powder during the desulfurization reaction, and despite many attempts, it has not been able to meet the strong demands of practical use, especially It was not possible to obtain an iron oxide desulfurization agent as a molded product of any shape with excellent initial and post-recycle abrasion strength.

The present invention was made in order to solve the various problems mentioned above, and is a novel oxidation method that enables efficient desulfurization in a wide temperature range and has excellent initial wear strength and post-regeneration wear strength. The purpose of the present invention is to provide an iron-based desulfurization agent and a method for producing the same.

In the present invention, the initial abrasion strength means the abrasion strength of a newly prepared desulfurizing agent, and the abrasion strength after regeneration is
It means the abrasion strength after heating and regenerating the desulfurizing agent after desulfurization treatment.

The desulfurization agent according to the invention is characterized in that it contains 40 to 95% by weight of iron oxide, 5 to 60% by weight of titanium oxide, and 0 to 30% by weight of silicon oxide, and the desulfurization agent according to the invention contains: Iron oxide or a precursor thereof, and titanium oxide or a precursor thereof (and in some cases, fine particle silicone) are mixed with at least one selected from Decnia sol, silica sol, and ferric hydroxide, shaped, and dried. , obtained by firing.

Iron oxides used in the present invention include iron ores such as hematite and limonite, loess, and iron oxides produced as by-products during the recovery of hydrochloric acid from iron plate washing waste acid. Examples include iron carbonate, iron sulfate, iron nitrate, iron halide, iron hydroxide, etc., but are not limited to these.

The titanium oxide used in the present invention may be either Rudil-type titanium oxide or anatase-type titanium oxide, and its crystals may be ungrown. The degree of growth of titanium oxide crystals can be determined by, for example, X-ray diffraction. The titanium oxide precursor may be anything that produces titanium oxide by firing, such as titanium tetrachloride, titanium sulfate, orthotitanic acid or metatitanic acid produced by hydrolysis of a solution of these titanium salts or reaction with an alkali. including, but not limited to.

In the present invention, the above iron oxide or its precursor;
titanium oxide or its precursor, and at least 1 ff selected from titania sol, silica sol, and ferric hydroxide.
The desulfurizing agent is obtained by intimately mixing with fi, shaping, drying and sintering.

Titania sol is obtained, for example, by hydrolyzing titanic acid with hydrochloric acid or nitric acid, or by peptizing metatitanic acid from the sulfuric acid method titanium oxide manufacturing process with alkaline earth chloride, nitrate, or the like. However, the titania sol used in the present invention is not limited in any way in its origin or manufacturing method.

Silica sol usually uses water glass as a cation exchange resin.
It can be obtained by ζ ion exchange or acid decomposition of water glass followed by dialysis. Alternatively, it can be obtained by hydrolyzing ethyl silicate, silicon sulfide, or silicon tetrachloride, or by heating silica gel in the presence of a small amount of alkali to peptize it. However, in the present invention, there are no restrictions on the origin or manufacturing method of the silica sol used. Further, the ferric hydroxide used in the present invention is obtained by neutralizing an aqueous solution of a ferric salt with an alkali or an alkali salt, washing the iq precipitate with water, and filtering the resulting cake-like ferric hydroxide. A slurry obtained by redispersing this cake in water can also be used.

In the present invention, when producing the desulfurization agent, iron oxide,
The reason why at least one of titania sol, silica sol, and ferric hydroxide is present together with titanium oxide or a precursor thereof is that these have a function and effect as a binder. It is necessary to use one amount of each of them so as to account for 5 weight percent or more of the desulfurizing agent in terms of oxide. This is because if the amount is less than 5% by weight, the resulting desulfurizing agent will not have sufficient initial abrasion strength.

Furthermore, in the present invention, since titania sol is also a titanium oxide precursor, it is clear that the desulfurization agent can be produced even if only titania sol is used as the titanium component of the desulfurization agent. Since ferric iron is also an iron oxide precursor, it is of course possible to produce a desulfurizing agent even if only ferric hydroxide is used as the iron component of the desulfurizing agent. As mentioned above, titania sol and ferric hydroxide not only exhibit a binder effect, but when they are used, they become titanium oxide and iron oxide components, respectively, in the desulfurization agent after firing, and constitute the components of the desulfurization agent. do. On the other hand, in the case of silica sol, if it is fired, it becomes silicon oxide, which can be used as a component of a desulfurizing agent in the same way as described above. However, silica sol is used primarily to exhibit its effect as a binder. Ru.

In this way, the composite consisting of iron oxide and titanium oxide or their precursors mixed with at least one of titania sol, silica sol, and ferric hydroxide is adjusted to have a moisture content suitable for molding, Next, it is molded into a desired shape by a conventionally known conventional molding method, such as extrusion molding, tablet molding, rolling molding, or the like.

In the preparation of the above-mentioned mixture, it is possible to add an appropriate shaping aid, for example, a pore-forming agent such as methylcellulose or Avicel, a lubricant, a moisture regulator, etc., as necessary, and then mold and bake the mixture. Needless to say. The shape of the molded product is not particularly limited, and examples thereof include a sphere, a cylinder, a cylinder, and a honeycomb.

Further, it can be made into fine particles by methods such as fil agitation granulation, fluidized granulation, and spray granulation, and used as a desulfurizing agent for fluidized beds. In addition, during molding, it is preferable to consolidate the desulfurizing agent to increase the ferric oxide content in order to increase the adsorption capacity.

After shaping as described above, drying and firing will yield the desulfurizing agent according to the present invention. Firing is usually done in an air atmosphere for 300
By heating to a temperature of ~600°C for 1-10 hours
ζ is carried out. The desulfurizing agent obtained in this way is usually 10 rrr/g or more, preferably about 40 to 1
It has a large specific surface area of 80rrr/g. Incidentally, in the present invention, the dried molded product can be incorporated into a desulfurization device and heated and fired by gas supplied to the desulfurization device, and such firing is also included in the firing included in the present invention.

In the production of the desulfurizing agent of the present invention, each of the above-mentioned components is
In the desulfurization agent, 40 to 95% by weight of iron oxide, preferably 50 to 90% by weight, and 5 to 60% by weight of titanium oxide,
67% by weight or preferably 10 to 50% by weight. In particular, from the viewpoint of desulfurization rate and abrasion strength, iron oxide 60~
Preferably, it consists of 85% by weight and 15-40% by weight of titanium oxide.

This is because if the amount of titanium oxide is too small, the abrasion strength will be poor, while if the amount of titanium oxide is too large, the desulfurization rate will decrease, which is not preferable.

In the present invention, iron oxide and titanium oxide or their precursors are added in order to prevent boiling when the mixture is fired, increase the specific surface area of the resulting desulfurization agent, and thus increase the desulfurization rate. A desulfurizing agent can be obtained by preparing a mixture containing fine silicic acid, kneading, drying and firing. Such fine particle silicic acid is also known as white carbon, and one of its characteristics is that it has a very large specific surface area. These fine particles of silicic acid may be produced by either a wet method or a dry method, and in the present invention, commercially available products can be used. Commercial products of fine particle silicic acid that can be suitably used in the present invention include, for example, Fine Seal, Hi Sil,
Balkasil, Calf.

Rex, Nip Seal, ]・Kushi Sylvitase Seal,
Among them, those having an average particle size of 10 to 50 mp and a specific surface area of 200 to 300 rrr/g are preferably used.

In the present invention, the above-mentioned fine-particle silicic acid and the above-mentioned silica sol are used in an amount of 30% by weight or less of the desulfurizing agent in terms of silicon oxide. That is, for these two cases, when using silica sol alone, when using finely divided silicic acid alone, and when using both silica sol and finely divided silicic acid, the desulfurizing agent is
It is necessary to use C in a range of 0% by weight or less. This is because when a large amount exceeding 30% by weight is used, the desulfurization agent has a large tendency to cause self-injurious effects on the desulfurization rate and abrasion strength of the desulfurization agent obtained. On the other hand, when the above-mentioned sifter and sifter sol act as a binder and are used for a long time, it is necessary to use the desulfurizing agent in an amount of 5% or more in terms of silicon oxide.

As described above, the desulfurization agent according to the present invention contains at least iron oxide, titanium oxide (or a precursor thereof), and, in some cases, particulate silicic acid selected from the above-mentioned titania sols, silica sols, and ferric hydroxides. Mixed lines with type 1,
obtained by drying and firing, has a large specific surface area, and
Not only does it have excellent initial abrasion strength and post-regeneration abrasion strength, but the presence of titanium oxide synergistically enhances the desulfurization effect of iron oxide. Furthermore, titanium oxide has excellent acid resistance and is highly resistant to sulfur oxides generated during regeneration of desulfurization agents, and combined with its high abrasion strength after regeneration, it can withstand repeated reuse over long periods of time. .

In addition, as titanium oxide is already known, it also has a catalytic effect to hydrolyze organic sulfur compounds such as carbonyl sulfide, so titanium oxide
It is also possible to remove sulfur compounds, in particular 25
In desulfurization at a low temperature of 0°C or lower, it is also suitable for removing organic sulfur compounds.

The desulfurizing agent according to the present invention is suitable for adsorbing and removing sulfides contained in gases such as coal gasification gas, heavy oil catalytic cracking gas, and catalytic reforming gas.

The composition of these gases varies depending on the type, but coal gasification gas contains -15 to 20% carbon oxide, 15% carbon dioxide 1O, 20% hydrogen 1O, and 30% water vapor.
0%, hydrogen sulfide 3000-110000pp, balance nitrogen. However, the desulfurizing agent of the present invention is not limited in any way in the type or composition of the target gas. Also,
The conditions for the desulfurization reaction of gas using the desulfurization agent of the present invention are appropriately selected depending on the type and composition of the target gas, but for example, in the case of the above-mentioned coal gasification gas, the temperature
~600℃, gas space velocity 1000~300001+r
, preferably under conditions of 5,000 to 20,000 hr'. Although the apparatus for the reaction is not particularly limited, for example, a reaction method using the desulfurizing agent of the present invention in a fluidized bed is preferably employed.

The regeneration of the desulfurization agent of the present invention is generally carried out in air at 500-800%
This is done by heating at a temperature of 0°C for 5 minutes to 10 hours. Strictly speaking, the iron sulfide produced by the reaction of iron oxide in the desulfurizing agent with hydrogen sulfide is returned to iron oxide by heating, providing a regenerated desulfurizing agent with excellent strength. Therefore, the desulfurizing agent of the present invention can be recycled and used repeatedly as described above.

Examples of the present invention are listed below, but the present invention is not limited to these Examples at all. Note that the desulfurization rate is calculated using the following formula.

Desulfurization rate (%) - ((Hydrogen sulfide concentration at the inlet of the reactor -
Hydrogen sulfide concentration at the outlet)/Hydrogen sulfide concentration at the inlet of the reactor), X I 00 Example 1 After coarsely crushing hematite, it was crushed finely to 350 mesh in a wet process. 4,000 g of this fine powder was peptized with metatitanic acid with barium nitrate, resulting in 540 g/7!
Add 3170 ml of titania sol with a concentration of 3,170 ml, mix thoroughly, and adjust the moisture content to be optimal for extrusion molding.
It was extruded using a 1.8 ml I'L die under a pressure of kg/cA. After molding, it was dried at 80°C and fired at a temperature of 500°C for 3 hours in an air atmosphere. This was crushed into particles having a particle size of 150 to 60 mesh to obtain a desulfurizing agent A for fluidized beds consisting of 70% by weight of iron oxide and 7s0% by weight of titanium oxide.

Similarly, desulfurization agents with different iron oxide and titanium oxide contents were cleaved using hematite and titania sols. Table 1 shows the relationship between titanium oxide content and initial abrasion strength for these. The abrasion strength was measured in accordance with the method specified in JIS K-1464, in which 50 g of desulfurizing agent was placed in a 200-mesh sieve, shaken for a predetermined period of time, and expressed as a percentage of the amount of powder under the 200-mesh sieve.

In addition, using each desulfurization agent obtained above, hydrogen sulfide 3000 ppm, water vapor 10%, hydrogen 1
A gas consisting of 0% and the balance nitrogen was treated at a temperature of 450°C and a space velocity of 10,000++r''.

The titanium oxide content in the desulfurization agent and 1 after starting the reaction.
The relationship with the desulfurization rate after time is also shown in Table 1.

Table 1 Note that the desulfurization agent containing 70% by weight of titanium oxide is shown for comparison, and although it has excellent initial abrasion strength, it is recognized that it is inferior in desulfurization rate.

Implementation full 2 A ferrous sulfate aqueous solution was oxidized in the air, and the pH was adjusted to 3 with ammonia.
．． 5, and the resulting precipitate was washed with water and dried to obtain goethite. Goethite as this iron oxide precursor,
The same titania sol used in Example 1 was mixed so that the resulting desulfurization agent contained 20% by weight in terms of titanium oxide, and the mixture was kneaded, molded, dried, and fired in the same manner as in Example 1, and then crushed. , 1 q of desulfurizing agent B was added.

Example 3 100 g of Geitai l-3' obtained in Example 2, 400 g of titanium oxide powder obtained by baking metatitanic acid in a SO'C, and the same Chikunia 7' l used in Example I 1,480 ml was kneaded, molded, dried and fired in the same manner as in Example 1, and then crushed to obtain ground sulfur agent Cf6.

Example 4 Aqueous ammonia was added to an aqueous ferric chloride solution, and pl+ was adjusted to 7.
The precipitate that has been neutralized to 0 is washed with water, dehydrated, and the water content is 8
5% ferric hydroxide was added. Hereinafter, the term ferric hydroxide simply refers to ferric hydroxide with a water content of 85%. While kneading 3300 g of this ferric hydroxide and 2200 ml of the same titania sol used in Example 1,
After removing moisture until the moisture content is suitable for extrusion,
It was molded, dried, and calcined in the same manner as in Example 1, and then crushed to obtain Itsutsu desulfurizing agent E.

Example 5 120g of the same titanium oxide powder used in Example 3 and 3300 g of ferric hydroxide obtained in Example 4 were added to Example 1.
After cross-wiring, molding and firing in the same manner as above, crush the mixture and use the desulfurizing agent E.
I got it.

Example 6 3100g of 1q gametai in Example 2 and Example 3
400 g of the same titanium oxide powder used in Example 4
940 g of ferric hydroxide obtained in Example 1 were kneaded, molded, and fired in the same manner as in Example 1, and then crushed to obtain a desulfurizing agent F.

Example 7 2790 g of hengara, 400 g of the same titanium oxide powder used in Example 3, and silica sol (Osan Kagaku Kogyo (+
Desulfurizing agent G was obtained by kneading, molding, and baking 1,600 g of Snortex 50) manufactured by A.1.

Actual hfM Example 8 The same titania silua used in Example 1, 41! Wednesday 16.67! Prepare titania sol diluted by adding
In addition to this, 11.5 kg' of goethite obtained in Example 2,
2 kg of the same titanium oxide powder used in Example 3,
4 kg of fine particle silicic acid (manufactured by Tokuyama Soda@Kushisil) were dispersed. This 11k liquid was subjected to °ζ spray granulation treatment in a spray dryer made by Ashizawa Niro Atomizer a'@, and then
It was baked in an air atmosphere at a temperature of 500° C. for 3 hours. This was sieved to obtain 150 to 60 mesh desulfurizing agent H.

Example 9 40ml of the same titania silua used in Example 1,
3,300 g of ferric hydroxide obtained in Example 4 and 1,600 g of the same silica sol used in Example 7 were kneaded, dried, calcined, and crushed in the same manner as in Example 4 to obtain a desulfurizing agent (■). Ta.

Example 10 800 g of the same fine particle silicic acid used in Example 8, 1480 ml of the same titania sol used in Example 1,
2820 g of ferric hydroxide obtained in Example 4 was added to Example 1.
After kneading, drying and firing in the same manner, the mixture was crushed to obtain desulfurizing agent J.

Comparative Example Goethite 310g obtained in Example 2 and aluminum resol (Alumina Sol-200 manufactured by Nissan Chemical Industries @) 12 pupils were kneaded, molded, dried and fired in the same manner as in Example 4, and then crushed. , Desulfurizing agent K was obtained.

The respective desulfurization agents obtained in Examples 1-10 and Comparative Examples above were subjected to desulfurization reaction under the same conditions as in Example 1, and the desulfurization rates one hour after starting the reaction are shown in Table 2. After reacting in this manner for 5 days, the desulfurizing agent was added to the air for 600 min.
The sample was regenerated by heating at a temperature of 1.5 mL for 1 hour, and used again for the desulfurization reaction under the same conditions.

Table 2 shows the changes in the wear rate and specific surface area of the desulfurizing agent after regeneration when the desulfurizing agent was repeatedly used and regenerated in this manner.

Further, using the desulfurizing agent C according to the present invention and the desulfurizing agent K obtained by IM in the above comparative example, hydrogen sulfide 3000
ppm, water vapor 1O%, balance nitrogen at a temperature of 4
The treatment was carried out at 50°C and a space velocity of 10,000 br-'. The desulfurization rate 1 hour after starting the reaction was 7 for desulfurization agent C.
5%, and 63% for desulfurizing agent K as a comparative example.

Example 11 This example shows that the desulfurizing agent according to the present invention has a decomposition catalytic effect on carbonyl sulfide. When desulfurizing agent B obtained in Example 2 was used to treat a gas consisting of 3000 ppm hydrogen sulfide, 11000 ppm carbonyl sulfide, 10% water vapor, and the balance nitrogen using a fluidized bed method at a temperature of 250°C and a space velocity of 1000 ml for 2 hours. The decomposition rate of carbonyl sulfide was as shown in Table 3. In the table, the first number shows the decomposition rate 30 minutes after starting the reaction, and the second number shows the decomposition rate 2 hours after starting the reaction.

Note that the decomposition rate is calculated by the following formula.

Decomposition rate (%) - [(COS concentration at the inlet of the reactor - cost degree at the outlet)/COS concentration at the inlet of the reactor] x
100 Table 3 It is clear that the desulfurization agent according to the invention maintains a constant high decomposition rate irrespective of the length of the reaction time.

Patent Applicant: Ishikawajima Ban M Heavy Industries Co., Ltd., 5-1 Ebisujima-cho, Sakai City, Sakai Chemical Industries, Ltd. Central Research Laboratory (0) Author: Tsutomu Hatanaka, Sakai Chemical Industry Co., Ltd. Central Research Laboratory, 5-1, Ebisujima-cho, Sakai City (applied) People Sakai Chemical Industry Co., Ltd. 5-1-226 Ebisujima-cho, Sakai City

Claims (3)

[Claims] (1) A desulfurizing agent comprising 40 to 95% by weight of iron oxide, 5 to 60% by weight of titanium oxide, and 0 to 30% by weight of silicon oxide. (2) It is characterized by mixing iron oxide or its precursor, and titanium oxide or its precursor with at least one selected from titania sol, silica sol, and ferric hydroxide, shaping, drying, and firing. Method for manufacturing desulfurization agent. (3) Mixing iron oxide or its precursor, titanium oxide or its precursor, and particulate silicic acid with at least one selected from eight of chiknia sol, silica sol, and ferric hydroxide, shaping, drying, and firing. A method for producing a desulfurizing agent, characterized by: