JPH0798149B2 - Method for producing desulfurizing agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a desulfurizing agent, and in particular, a sulfur compound contained in a high-temperature reducing gas obtained by gasifying heavy oil or its distillation residue, coal and the like. TECHNICAL FIELD The present invention relates to a method for producing a high-performance and high-strength desulfurizing agent, which absorbs and removes by dry method.

[Conventional technology]

In recent years, as a measure against the soaring crude oil price and the heaviness of imported crude oil, the development of utilization technology of coal, inferior residues, etc. has been promoted, and gasified gas from this is used as a fuel source for power generation, The method of using the raw material for chemical synthesis is a typical example.

However, although this gasification product gas contains several hundred to several thousand ppm of sulfur compounds, depending on the raw material coal or heavy oil, it must be removed for pollution prevention or corrosion prevention of downstream equipment. There is. Hydrogen sulfide (H ₂
As a method for dry removal of S), carbonyl sulfide (COS), etc., a desulfurizing agent containing iron oxide (Fe ₂ O ₃ ) as a main component is generally used, as proposed in JP-A-53-37582. Even under pressure such as coal gasification gas, it absorbs sulfur compounds at a high temperature of 400 to 600 ℃ and becomes iron sulfide (FeS). Then, it is returned to Fe ₂ O ₃ by being regenerated at a high temperature of 450 to 850 ° C., so that it is possible to maintain high desulfurization performance while improving thermal efficiency by effectively utilizing waste heat.

However, desulfurizing agents consisting only of Fe ₂ O ₃ will collapse due to changes in molecular weight when the desulfurization / regeneration reaction is repeated.Therefore, in order to obtain a desulfurizing agent having strength that can withstand long-term use, it is usually alumina, silica, titania, silica. -It has been attempted to support Fe ₂ O ₃ on a porous inorganic refractory such as alumina to form it into a practical shape.The shape that can be filled in a fluidized bed or moving bed reactor is spherical or circular. Although columnar and cylindrical shapes have been developed, a high-strength and high-performance desulfurizing agent including abrasion resistance when flowing or moving has not been found.

On the other hand, the inventors of the present invention, the gasification product gas to which this desulfurizing agent is applied contains a large amount of dust due to the raw material, and the dust concentration is 10 mg / Nm ³ or less even after dust removal. It is difficult to control, and the fixed bed desulfurization method using the desulfurization agent of the honeycomb structure that ventilates the processing gas in parallel flow so as not to cause the blockage of dust is considered to be the optimal method. I have been studying.

The desulfurizing agent applied to the fixed bed type is required to have long-term durability because it cannot be appropriately replaced during use as compared with other methods.
Therefore, in addition to high desulfurization performance, it is indispensable to select a base material with high SO _X resistance, heat resistance, and high strength, and to establish a desulfurization agent preparation technology that will exhibit stable desulfurization performance for a long period of time. .

As a material satisfying the above characteristics, TiO ₂ -Fe ₂ O ₃ system (Japanese Patent Publication No. 59
No. 32169), TiO ₂ —SiO ₂ —Fe ₂ O ₃ system (JP-A-59-39345).
However, there is no disclosure of a specific method for producing a high-quality and practical desulfurizing agent.

On the other hand, TiO ₂ is thermally denatured, but there is no particular prior art on a method for preventing this thermal degeneration.

[Problems to be Solved by the Invention]

The desulfurizing agent should not be altered by SO ₂ and SO ₃ gas generated in the regeneration reaction, and the temperature should be 600-800 ℃ to prevent the sulfate from remaining.
It is required not to be affected by thermal deterioration during regeneration. Ti
O ₂ is excellent in SO _X resistance and is preferable as a base material for desulfurizing agents, but anatase-type TiO ₂ usually receives only a thermal history of about 500 to 650 ° C, and is regenerated at 600 to 800 ° C. It causes deterioration and is one of the causes of deterioration of the performance of the desulfurizing agent during use. JP-A-59-39345 discloses that anatase type, rutile type, and ungrown crystal titanium oxide can be applied.
If the crystallization temperature of TiO ₂ is equal to or lower than the regeneration temperature used as a desulfurizing agent, the TiO ₂ crystals are thermally deteriorated and cannot be used stably for a long period of time. Therefore, when anatase-type TiO ₂ is used, a method of firing a honeycomb formed body at 800 ° C. or higher is used, but the problem is that thermal strain remains inside the formed body.
On the other hand, the TiO ₂ powder is preheated to 800 ° C or higher, preferably 1000 ° C.
In the method of forming a molded body after firing in, the moldability becomes extremely poor and the strength after molding is insufficient.

The present invention intends to provide a method for producing a desulfurizing agent which suppresses these alterations due to heat and gas, has practical strength, and maintains high desulfurization performance for a long period of time.

[Means for Solving the Problems] The present invention is to absorb a sulfur compound such as hydrogen sulfide and carbonyl sulfide in the coexistence of anatase-type titanium oxide to titanium oxide powder that has been fired at a temperature higher than the regeneration temperature of a desulfurizing agent in advance. Is a method for producing a desulfurizing agent, which comprises mixing, molding, and baking the metal oxide.

[Action]

The crystal structure of titanium oxide powder changes to amorphous, anatase type, and rutile type as the heating temperature is raised. In addition to high desulfurization performance, desulfurization agents such as the present invention are required to have heat resistance and high strength as a molded body. In particular, the fixed bed desulfurization method requires characteristics other than desulfurization performance. In order to increase the heat resistance of titanium oxide, a method of firing at a temperature as high as possible is generally used.
A method of firing at 1000 ° C is used with 800 ° C as a guide. However, the titanium oxide powder fired at such a high temperature does not have the anatase type but has a crystal structure and properties close to those of the rutile type, and the formability when forming a granular, cylindrical, honeycomb-shaped or other shaped body is reduced. To do. In addition, metal oxides such as iron oxide that absorbs and removes sulfur compounds such as hydrogen sulfide and carbonyl sulfide are generally powdered by pretreatment with silica in order to impart thermal stability. In the case of mixing with a titanium oxide powder having heat resistance, for example, extrusion molding, practical strength of the molded body is difficult to be exhibited. Therefore, in order to obtain a practical desulfurizing agent, it is necessary to improve the moldability and the strength of the molded body.

The present invention has been made from the above point of view, when mixing an absorbing metal oxide of a sulfur compound and a titanium oxide powder which have been subjected to pretreatment for imparting heat resistance in advance, anatase-type oxidation in order to improve moldability. It is characterized in that a small amount of titanium powder is added. That is, when the anatase-type titanium oxide powder is added to the high-temperature calcined titanium oxide powder calcined at about 1000 ° C., the anatase-type titanium oxide acts as a molding-improving agent, so that the strength of the molded body is remarkably improved.

Since anatase-type titanium oxide is a homologue of titanium oxide that has been preheated at high temperature, absorption metal oxides of sulfur compounds, for example, SiO ₂ -Fe ₂ O ₃ described above, Cr, Mn, Mo, W, Z
When mixed and prepared with an oxide containing one kind of metal such as n and Cu, it is convenient to treat it as titanium oxide equally.

Although the moldability improves as the amount of the anatase-type titanium oxide powder added here increases, the heat resistance as a molded body decreases, so it is arbitrarily determined from the relationship between desulfurization performance and strength required for practical use. However, the addition amount of the anatase-type titanium oxide powder is preferably half or less of the titanium oxide powder fired at high temperature.

〔Example〕

Iron nitrate to a silica sol solution 5kg containing 20% by weight of silica _{[Fe (NO 3) 3 · 9H} 2 O ] 10.1kg and deionized water 15kg
Was added and stirred for 1 hour, then 15 wt% ammonia water 8.26 kg
Was adjusted to pH 7.5 to prepare a slurry composed of iron hydroxide and silica gel. This slurry was over-dehydrated, washed with ion-exchanged water, dried, calcined at 600 ° C. for 5 hours, and pulverized with a ball mill to obtain iron oxide-silica powder having heat resistance.

After drying the titanium hydroxide cake, 1 kg of anatase-type titanium oxide powder and 0.5 kg of glass fiber were uniformly mixed with 5 kg of high-temperature-baked titanium oxide powder obtained by firing at 1000 ° C. for 12 hours, and ion-exchanged water 6 l, ethylene oxide 90 g and 90 g of carboxymethyl cellulose was added, and the pH was adjusted to 8.0 with 15% by weight aqueous ammonia. To this mixture of titanium oxide powder,
2.75 kg of the above iron oxide-silica powder was added. This mixture was kneaded for 1 hour, adjusted to have a water content of 24% by weight, and extruded with an auger machine type extruder to form a rectangular parallelepiped honeycomb molded product with a side of 75 mm and a length of 600 mm (pitch 5.1 mm). , Wall thickness 1.2 mm) was obtained. At this time, the extrusion rate was as good as 780 mm / min, and even after drying at room temperature for 1 day, drying at 50 ° C. for 5 days and firing at 800 ° C. for 5 hours, cracking did not occur and the moldability was good.

Next, a desulfurizing agent was produced by the same method except that the compounding ratio of the high temperature calcined titanium oxide powder and the anatase type titanium oxide powder was changed. Table 1 summarizes the titanium oxide compounding ratio of these desulfurizing agents, the crush strength in the gas flow direction, and the degree of deterioration of desulfurization performance after heat treatment at 850 ° C. for 100 hours. The desulfurization performance evaluation test conditions are as follows.

As is clear from Table 1, the addition of anatase-type titanium oxide improves the strength of the molded product and also improves the heat resistance. Further, when the amount of anatase-type titanium oxide added is increased, the moldability is improved (the extrusion rate is increased), but the rate of increase in crushing strength is small, and when added in the same amount as the high temperature calcined TiO ₂ powder, Heat resistance is inferior to that without anatase type TiO ₂ powder.

〔The invention's effect〕

According to the present invention, the moldability of the desulfurizing agent is improved, and the strength of the molded body is improved without impairing the performance and heat resistance of the desulfurizing agent, so that the practicality is enhanced.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location B01D 53/52 (72) Inventor Toshikuni Sera 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries (72) Inventor Toru Seto 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (72) Kaoru Mitsuoka 4-6-22 Kannon-shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture No. Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (72) Inventor Masayuki Hanada 1-38-38 Hatata, Wakamatsu-ku, Kitakyushu, Fukuoka Prefecture (72) Morio Fukuda, 178 Shioya, Wakamatsu-ku, Kitakyushu, Fukuoka

Claims (1)

[Claims] 1. A metal oxide which absorbs a sulfur compound such as hydrogen sulfide and carbonyl sulfide in the presence of anatase-type titanium oxide is mixed with a titanium oxide powder which has been previously fired at a temperature higher than the regeneration temperature of a desulfurizing agent, and molding. A method for producing a desulfurizing agent, which comprises: