JP2009045597A - Tar reforming catalyst, manufacturing method thereof, and steam reforming method for tar using the catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst which suppresses a carbon deposition, and converts efficiently tar produced by a heat decomposition of a carbonaceous resource into a combustible gas, and is strong to a sulfur (hydrogen sulfide) poisoning by paying attention to an iron-dolomite-based catalyst available at low costs and easy to prepare, a manufacturing method for the catalyst, and a reforming method. <P>SOLUTION: The catalyst is used for the method for reforming tar in which the phyrolysis gas containing tar, produced by the heat decomposition of the carbonaceous resource, is steam-reformed, by which the reformed gas containing mainly carbon monoxide and hydrogen is produced. The catalyst for reforming tar comprises a mixture of ironstone, dolomite, and nickel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a technology for efficiently converting tar generated by pyrolysis (steam reforming) when using a method for converting various carbonaceous resources into raw fuel gas. The present invention relates to a reforming catalyst, a method for producing a tar reforming catalyst, and a steam reforming method for tar using the tar reforming catalyst.

  In recent years, the concept of 3R (reduce, reduce, reuse, recycle) has started to be recognized as a common concept, supported by policies. The so-called waste such as products after use or after breakdown / destruction and by-products at the time of product production is mainly incinerated or landfilled. Doing this will be one answer to the response to the global warming issue. However, wastes have various properties, many of them have low energy density, and the burden of gas purification after processing is large. There are few processes that can be economically independent on a scale.

  Most of the waste contains carbon, and although the calorific value is generally low, it can be regarded as a carbonaceous resource that is not different from coal, oil, natural gas, etc.

  As a typical example of waste processing, there is a waste incineration power generation method that collects waste waste (household waste) as a target, and collects the waste incineration with steam power generation and collects it as electric power. In recent years, power generation at a power transmission end efficiency of nearly 30% has been achieved by improving boiler materials, adjusting raw materials (using RDF), improving efficiency by using external fuel (super garbage power generation), etc., from the conventional power transmission end efficiency of 10-15%. The incinerator began to operate as a real machine. In addition, as a treatment method where the adoption of actual equipment in the local government is increasing due to tightness of final disposal sites and dioxin regulations, aiming at volume reduction / detoxification treatment of ash and reduction of dioxin, gasification melting at high temperature to melt ash There is a so-called waste gasification and melting technology that turns slag into power generation. There are many types of this technology. I) Direct melting type (using a shaft furnace, etc., thermal decomposition, gasification, combustion and melting are performed in the reactor in the previous stage, and combustion is performed in the subsequent stage to recover energy in the boiler and steam turbine. Ii) Pyrolysis + combustion / melting type (gas, tar and char generated by low temperature pyrolysis in kiln etc. are burned at high temperature with sufficient air, and energy is recovered by boiler and steam turbine.) Iii) Pyrolysis + gasification type (After generating low temperature pyrolysis in fluidized bed, shaft furnace, etc., gas is converted to high temperature, combustible gas is generated, and after cleaning up through dust removal and gas purification processes Gas turbines, power generation by gas engines, or gas as chemical raw materials.)

  In the combustion-steam power generation method of i) and ii), the tube side (steam) temperature needs to be lower than the acid corrosion temperature due to boiler tube corrosion due to chlorine contained in the waste, and the steam conditions to be recovered Therefore, it is difficult to increase the power generation efficiency from the current level.

  The present invention mainly belongs to the technical category of iii) described above, and while high-efficiency energy conversion is possible, the treatment of residual tar is one problem. I use it.

  As patents of technologies belonging to this range, the inventors of the present invention have proposed a method of gasifying waste with higher efficiency than the prior art by combining thermal decomposition, gasification, and reforming in Patent Document 1.

  Further, as a prior art / patent before that, Patent Document 2 proposes a method and apparatus for pyrolyzing waste and reforming pyrolysis tar with a partial oxidation gas of pyrolysis char to produce a combustible gas. ing.

  In Patent Documents 1 and 2, tar generated by thermal decomposition undergoes a steam reforming reaction in a reforming furnace, and is converted into carbon monoxide and hydrogen. The reforming temperature in Patent Document 1 is 900 ° C. to 1200 ° C. (tar trouble at less than 900 ° C., and fusion / adhesion of fly ash above 1200 ° C.). The reforming temperature in ˜1200 ° C. and Patent Document 2 is 800 ° C. or higher (no particular mention is made for the reason).

Generally, as seen in Non-Patent Document 1, etc., the temperature effective for steam reforming of coal (brown coal) tar is about 900 ° C. In terms of a reforming catalyst, Patent Document 3 proposes a catalyst using a composite of dolomite and nickel salt during gasification. This means that when gasifying organic gasified products, tar is generated at temperatures below 1000 ° C, causing troubles. By introducing a catalyst into the gasification furnace itself, the temperature is lowered while the reaction proceeds. I'm trying (around 800 ° C). Generally, as shown in Non-Patent Document 2, as a hydrocarbon reforming catalyst, there is a numerical value of 800 ° C. to 900 ° C. for Ni catalyst in methane reforming. Further, in Patent Document 4 which presented details of catalyst types for hydrocarbons (not including tar reforming), four types of M, Ni, Mg, and O (M: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, Cd, Al, Si) and a hydrocarbon reforming catalyst that is relatively resistant to sulfur poisoning is proposed (H _{2 in the} examples). When the S concentration is 2000 ppm, the methane conversion rate is 8.2% to 53.8%). Patent Document 5 refers to steam reforming of pyrolysis gas (coke oven gas: COG) using coal as a raw material. High sulfur compounds (H ₂ S concentration of 2019 ppm, 0.1 ppm for hydrogen production by naphtha steam reforming) A solid solution catalyst in which Ni is deposited in the form of nanoclusters on the surface from the inside of the support is suitable for steam reforming of crude COG containing (which is desirable) (methane conversion 50%, there is a description of tar reforming) Is shown by the amount of product gas increase after decomposition, and tar conversion is unknown.)

  In addition, regarding the iron / alumina catalyst used in Patent Document 5, there was a description that the performance was not good. In general, an iron-based catalyst is hardly used for reforming purposes because the catalyst is deactivated, for example, carbon deposition occurs on the catalyst surface.

JP 2004-41848 A JP 11-294726 A JP 2006-68723 A JP 2004-900 A JP 2003-55671 A NEDO International Joint Research Grant Project (NEDO Grant) Report EA-04 “Liquefied coal fluidized bed reforming for low environmental load and high efficiency power generation using chemical heat pump concept” (1999-2001) Chemical Engineering Handbook 5th edition, p211

When steam reforming is carried out in a system without a catalyst, tar tends to decrease as the temperature increases, but there is almost no tar (for example, less than 100 mg / Nm ³ ; tar in gas that can be used as it is for combustion in a gas engine or the like. In order to obtain a (concentration), it is necessary to increase the temperature to 1100 ° C. or higher, which causes another problem. That is, there is a problem that the generation of soot suddenly increases when the temperature exceeds 1100 ° C. From the viewpoint of gas utilization, both tar and soot are required to be removed. The significance is low. Therefore, even if tar remains, the operating conditions at normal temperature (up to about 1100 ° C. according to the inventors' knowledge) must be taken. In addition, since the remaining tar is not used when gas is used (combusted as gas fuel or used as a raw material for chemical synthesis as CO, H ₂ gas, etc.), not only becomes a latent heat loss of the calorific value process. Moreover, the removal process of a water treatment system etc. is required, and economical efficiency, such as generated wastewater treatment cost, deteriorates.

  On the other hand, in a system with a catalyst, a Ni-based catalyst is often used because of its high activity. However, according to Patent Document 3, the entire gasification reaction is performed in a fluidized bed, and a nickel / dolomite-based catalyst is introduced therein. The temperature is set to 600 ° C to 900 ° C. In the case of the method in which the gasification reaction and the catalytic reaction are performed at the same time, there are limitations on the gasification conditions. Changes, changes in gas components; particularly, changes in the amount of water vapor affect the catalytic reaction), and a decrease in catalytic activity also affects a decrease in gasification characteristics (reforming reaction can be performed under the same gasification conditions) If it becomes insufficient, the remaining tar has a lot of unstable factors in terms of operation and performance, such as lowering the cold gas efficiency and gas conversion rate as a result.

Further, in general, sulfur poisoning is an important problem for nickel-based catalysts, and in order to solve this, Patent Document 3 discloses that nickel is 5 to 30 wt%, ammonium tungstate as a catalyst having particularly high sulfur poisoning resistance. , Cobalt nitrate, ammonium molybdate 5-30 wt% (remaining dolomite; estimated), and in Patent Document 4, a catalyst represented by aM · bNi · cMg · dO (M: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, Cd, Al, Si), a + b + c = 1, 0.02 ≦ a ≦ 0.99, 0.01 ≦ b ≦ 0.99, 0. In the case of 01 ≦ c ≦ 0.97 (both molar ratios), it becomes a catalyst having high performance and sulfur poisoning resistance (methane conversion rate of 10 to 99% in the presence of H ₂ S). COG made from raw materials In steam reforming, a solid solution catalyst such as Ni is deposited on the surface from the carrier inside the nanocluster form the steam reforming of crude COG containing hydrogen sulfide is a preferred.

  These require the use of expensive Ni and other transition metals in a large amount of 5 to 30%, and moreover, they are complicated catalyst systems, special manufacturing methods and special surface conditions. Strict manufacturing control is required, including cost and manufacturing cost increases and preparation methods. In general, hydrocarbons and tar reforming catalysts are considered excellent if they stably maintain a conversion rate of 70% or more (mass ratio at which hydrocarbons and tar are converted to gas).

  The present invention pays attention to an iron / dolomite-based catalyst that is inexpensive and easy to obtain and prepare, and converts tar generated from thermal decomposition of carbonaceous resources efficiently into combustible gas by suppressing carbon deposition, and sulfur (sulfurization). (Hydrogen) It is an object to provide a poison-resistant catalyst, a catalyst production method and a reforming method.

  The present invention is an effective method for solving the above problems and has the following features.

  (1) A catalyst used in a tar reforming method in which a pyrolysis gas containing tar generated by pyrolysis of a carbonaceous raw material is steam reformed to generate a reformed gas mainly composed of carbon monoxide and hydrogen. A tar reforming catalyst characterized in that iron ore, dolomite and nickel are mixed.

  (2) The tar reforming catalyst according to (1), wherein the pyrolysis gas containing tar further contains hydrogen sulfide.

  (3) The tar reforming catalyst according to (1) or (2), wherein the carbonaceous raw material includes at least one of biomass, plastic, and general waste.

  (4) The method for producing a tar reforming catalyst according to any one of (1) to (3), wherein iron ore and dolomite are mixed, and then the mixture is impregnated with a nickel-containing aqueous solution. Drying and calcining to produce a tar reforming catalyst, impregnating iron ore with a nickel-containing aqueous solution, drying and calcining, and then mixing the calcined product with dolomite to produce a tar reforming catalyst, or A method for producing a tar reforming catalyst comprising impregnating a nickel-containing aqueous solution in dolomite, drying and calcining, and then mixing the iron ore with the proof organism to produce a tar reforming catalyst.

  (5) When the catalyst is produced, the total mass of the raw iron ore, the raw dolomite, and nickel in the raw nickel-containing aqueous solution is 30% by mass to 70% by mass. And the mass ratio of the said nickel shall be 0.05 mass% or more, The manufacturing method of the catalyst for a tar reform as described in (4) characterized by the above-mentioned.

  (6) A tar steam reforming method using the tar reforming catalyst according to any one of (1) to (3), wherein steam and tar are reaction raw materials for steam reforming. A method for steam reforming of tar, wherein a molar ratio of medium carbon (water vapor / carbon in tar) is 1 mol / mol or more and 5 mol / mol or less.

  In addition, the carbonaceous raw material made into object by this invention points out what has calorific value, such as fossil fuels, such as a waste material, coal, and oil shale. For example, waste refers to biomass, plastics, general waste, etc., specifically agricultural biomass (straw, sugarcane, rice bran, vegetation, etc.), forestry biomass (paper waste, lumber waste, thinned thinning) Wood, charcoal forest, etc.), livestock biomass (livestock waste), aquatic biomass (fishery processing residue), waste biomass (food waste, RDF: solid waste fuel; Refused Derived Fuel, garden trees, construction waste, sewage Sludge), hard plastic, soft plastic, shredder dust, etc. General waste is garbage other than the 19 types designated as industrial waste, and is business waste that contains a lot of household waste collected by local governments and papers from businesses. However, those that contain almost no carbonaceous matter, that is, separated metals, glass, debris, etc., are not covered. As other carbonaceous resources, considering the target raw material property of the present invention that tar is generated by pyrolysis, it is not preferable for global warming countermeasures. Use of coal, oil shale, oil sand, etc. as fuel, or mixed use with waste may be used.

  In the present invention, “steam reforming” is a reaction in which tar mainly composed of carbon, hydrogen, and oxygen is converted into carbon monoxide and hydrogen by steam, for example, Expressed.

C _n H _m O _l + H ₂ O → CO + H ₂
As a reaction that occurs in parallel, the rate is slower than that of steam reforming, but reforming by carbon dioxide, for example, by the following formula has also occurred.

C _n H _m O _l + CO ₂ → CO + H ₂
Further, the tar after pyrolysis is gaseous (gas) at high temperature, and the tar reforming reaction by the catalyst partially includes a steam reforming reaction of a gas component in the pyrolysis gas (the reaction cannot be separated, for example, methane). Steam reforming reaction). Therefore, the gas existing after the reforming reaction is generally called reformed gas.

  A catalyst capable of efficiently steam reforming tar generated by pyrolysis of carbonaceous resources by using inexpensive or readily available iron ore and dolomite and adding a relatively small amount of nickel The catalyst can be used, and a reduction in catalytic activity due to carbon deposition that is likely to occur in an iron-based catalyst can be suppressed, and the tar can be efficiently steam reformed. Further, steam reforming can be performed efficiently even under the condition where hydrogen sulfide coexists, and the generated combustible gas can be increased. Furthermore, in a preferred example of the present invention, the amount of Ni added can be significantly reduced as compared with the conventional Ni-based catalyst, so that it is possible to obtain a sufficiently inexpensive catalyst as compared with the conventional Ni-based catalyst.

  A typical flow of a carbonaceous feed pyrolysis process using the catalyst of the present invention is shown in FIG. The carbonaceous raw material 1 is supplied to the pyrolysis furnace 2 and heated up to the thermal decomposition temperature (in the case of a composite carbonaceous raw material, usually 500 ° C. or higher). In the case of this example, the pyrolysis furnace 2 uses a shaft furnace, and the carbonaceous raw material 1 supplied from the upper part is piled up in the furnace, heated gradually while descending, dried, pyrolyzed and heated. Cracked gas and pyrolytic tar 3 and carbide 4 are generated, and the carbide 4 is discharged from the lower part of the furnace. As for the carbonaceous raw material 1, any material that generates tar by thermal decomposition at several hundred degrees Celsius can be applied. For example, in addition to waste wood chips (biomass), plastic, general waste, etc. can be used. It is. In the examples described later, waste wood chips (biomass) are mixed with coal for thermal decomposition and reforming. This is because waste wood chips that are easy to decompose and contain a large amount of water-soluble tar, and high-temperature heat By using coal that requires cracking and oil-soluble aromatic-rich coal, we can see the catalytic reforming effect of extreme tars. In the present invention, these tars can be reformed. Therefore, it is considered possible to cover plastics that generate tar with intermediate properties, general waste garbage, agricultural / fishery / waste biomass.

The heat source for the pyrolysis is not particularly limited, but in this example, the combustion heat obtained by partially burning the combustible gas partially combusted hot gas or carbide is used. The pyrolysis furnace 2 is not necessarily a shaft furnace, and other furnaces capable of pyrolysis, such as kilns, fixed bed furnaces, and fluidized bed furnaces, may be employed. The pyrolysis gas and pyrolysis tar 3 generated from the pyrolysis furnace 2 are introduced into the reforming furnace 5 at a temperature of about 300 ° C. to 700 ° C., and simulated by C _n H _m O ₁ by a steam reforming reaction of tar. Tar reacts with H ₂ O in the gas (when it is insufficient, steam is introduced in the reforming furnace) and converted to CO and H ₂ . The reaction proceeds when the tar and water vapor come into contact with each other even in the gas phase, but there are few opportunities for contact and a certain temperature (about 1100 ° C.) is required. Therefore, the catalyst is used to accelerate the reaction and lower the temperature (reaction rate). Improvement). Due to the presence of the catalyst, tar adheres to iron and nickel on the catalyst surface (forms an intermediate), and water vapor adheres to the nearby catalyst surface (oxygen-related group), thereby changing the binding force of the raw material. (Weakens), the reaction is accelerated. For this reason, it is desired that the catalyst easily come into contact with the gas (tar). For example, in the embodiment of the present invention, the reforming catalyst 12 molded into a granular shape (2 to 3 mm diameter, several mm length) is fixed bed. This is realized by filling the basket (catalyst zone), and installing it immediately after (rear stage) the reforming furnace 5 and allowing the entire amount of gas to pass therethrough. The installation method is not particularly limited, such as a fixed bed (filling in a furnace, filling a fixed object such as a basket, etc.), a moving bed (equipped with a charging and cutting mechanism), a fluidized bed, and the like.

  The reformed gas 6 produced by reforming is purified by the gas processing device 7 and then used as the product gas 8 in the subsequent gas use process 9. In the reforming furnace 5, a steam reforming reaction of tar proceeds with a catalyst to produce a reformed gas 6 mainly composed of carbon monoxide and hydrogen. The temperature required for the reforming reaction is 300 ° C. to 700 ° C. In order to compensate for the sensible heat of the pyrolysis gas and the pyrolysis tar 3 and the lack of temperature, it is covered by the partial combustion heat of the pyrolysis gas using an oxidant 10 (for example, oxygen / oxygen-containing gas). The steam required for the steam reforming reaction uses water brought in from the carbonaceous raw material 1 or combustion reaction water generated in the process of creating the heat source of the pyrolysis furnace 2. And a predetermined water vapor / tar carbon molar ratio. The relationship between the amount of water vapor in the actual pyrolysis gas and carbon in tar is often 0.1 to 10 mol / mol. The water vapor in the gas consists of the total amount of moisture brought into the raw material, the moisture contained in the pyrolysis heat source (partially combusted high-temperature gas or part of the combustion of the combustible gas) and the water vapor to be added. There are a method of calculating the number of moles by dividing by the molecular weight of water (18), a method of measuring the water vapor mass in the gas before the reforming furnace, and calculating the number of moles by dividing by the molecular weight of water (18). There are various analysis methods for carbon in tar. For example, after tar recovery (after suction with a constant velocity suction method, etc., it is absorbed with a solvent such as methylene chloride. The solvent is then stripped and recovered as tar). The mass% is measured, the tar amount is multiplied by the mass%, and divided by the carbon molecular weight (12) to calculate the number of moles of carbon in the tar.

  The tar reforming catalyst in the present invention is characterized in that iron ore, dolomite and nickel are mixed.

  In the present invention, the mass ratio is determined as follows: As the catalyst mass, iron ore and dolomite adopt the raw material dry mass (state of oxide) as it is, and nickel impregnates and supports nickel-containing water-soluble compounds (iron ore). In this case, the mass of nickel nickel (atomic weight 58.7) contained in nickel nitrate hexahydrate: molecular weight 290.8) was preferably used. That is, the total mass of the raw iron ore, the raw material dolomite, and the total nickel mass in the raw nickel-containing aqueous solution is used as the denominator, and the total mass of the raw iron ore, raw dolomite, and nickel in the raw nickel-containing aqueous solution ( A value obtained by dividing by 100 and multiplying by 100 was defined as each mass%. When making a catalyst with only iron ore, dolomite, and nickel, iron ore: dolomite: nickel = 50 mass%: 49 mass%, nickel 1 mass%, iron ore: dolomite: nickel nitrate May be prepared at a ratio of 50: 49: 4.95 on a mass basis (4.95 = 1 × 290.8 / 58.7). In addition, although it shows in detail in the below-mentioned Example as a mixing | blending, iron ore 30 mass% or more and 70 mass% or less and nickel 0.05 mass% or more are suitable.

  Inevitable impurities are allowed to be mixed into the catalyst during the production process. Further, metals, metal oxides, molding binders and the like other than those described above can be used as long as they do not affect the catalyst characteristics. For example, in order to develop strength, it is possible to mix alumina, silica, etc., which have good high-temperature characteristics and can be expected to resist pulverization, and to supplement weakness in the bonding force between catalysts (alumina, silica, magnesia, calcia) Etc.) in some cases.

  In that case, the amount of input raw material may be determined in consideration of the mass change before and after drying and baking as in the case of nickel nitrate. Regarding nickel, other compounds (eg, nickel chloride hexahydrate, nickel formate dihydrate, etc., which are water soluble and thermally decomposed to leave nickel metal), and fine metal as it is as a nickel source You can use it. As for dolomite, in the present invention, in order to clarify the mass and reduce the change in strength, a natural dolomite fired product is used, but artificially constructed dolomite and unfired dolomite (ascertain the amount of water, It may be used under the condition that there is no problem in strength after drying and firing.

The catalyst used in this system is a mixture of iron ore and basic baked dolomite powder (mainly MgO, CaO), pressure-molded, crushed and sized (comparative: no nickel) Catalyst), an aqueous solution of nickel nitrate hexahydrate impregnated with the granulated product, dried in a dryer at 120 ° C., and air-fired at 400 ° C. for 2 hours, an aqueous solution of nickel nitrate hexahydrate Impregnated with iron ore powder, dried in a dryer at 120 ° C, calcined in air at 400 ° C for 2 hours, physically mixed with calcined dolomite powder, crushed and sized, nickel nitrate 6 An aqueous solution of hydrate is impregnated into a calcined dolomite, dried with a dryer at 120 ° C., air calcined at 400 ° C. for 2 hours, physically mixed with iron ore powder, pressure-molded, crushed and sized, (Manufacturing example of powder mixing method) . In addition, kneading firing method (production example: Ni impregnated iron ore and calcined dolomite powder are physically mixed, then water is added to form a paste, mixed, dried and fired), impregnation method (production example: iron nitrate and nitric acid) After adding calcined dolomite to an aqueous nickel solution, stirring, drying, and calcining), precipitation method (manufacturing example: iron nitrate and nickel nitrate, calcined dolomite dissolved in water, mixing with stirring, and after suction filtration) However, since it was not much different from the powder mixing method, a powder mixing method that is the simplest to prepare and does not require skill is adopted. Using a nickel salt, drying, calcining, while a uniformly things to stabilized dispersed in the catalyst naturally be an aqueous solution, to release the NO ₃ nitrate is decomposed, the reforming It also aims to create suitable pores.

The iron ore used in the present invention is basically of any type, but in particular pisolite ore (also called limonite: for example, lobe river ore, Fe ₂ O ₃ · nH ₂ O = FeOOH) is a hematite ore ( Fe ₂ O ₃ ), magnetite ore (Fe ₃ O ₄ ), and maramamba ore (Fe ₂ O ₃ .FeOOH) are preferred. This is presumed to be because pisolite ore has a fish egg-like structure and easily develops pores of an appropriate size.

Example 1
In FIG. 2, as a comparison of tar reforming performance depending on the metal type, an example of the iron / dolomite / Ni catalyst of the present invention and Cr, Mn, Co, Cu, Zn instead of Ni were used as a comparative example. The reforming results with S / C = 2 and 5 for the catalyst are shown. Here, S / C is the molar ratio of stean / carbon = water vapor / carbon in tar. The iron ore was a lobe river ore used for iron making, and the dolomite was a baked dolomite manufactured by Ueda Lime Manufacturing Co., Ltd. Regarding the production method, among the methods described above, an iron ore powder is impregnated with an aqueous solution of nickel nitrate hexahydrate (nitrate is also used for other metals) and dried in a dryer at 120 ° C., and then at 400 ° C. for 2 hours. After air calcination, a method of physically mixing with baked dolomite powder, press molding, crushing, and sizing was used. In order to match the test conditions, iron ore: calcined dolomite = 50: 50 (mass ratio) in the case of no added metal, iron ore: added metal: calcined dolomite = 50: 1: 49 (mass ratio) in the presence of the additive metal. ), The reaction temperature (reforming temperature) is 900 ° C., W / F = 5.6 g · h / mol (GHSV = 4200 h ⁻¹ ), steam / carbon in tar = 2 and 5 (both mol / Mol).

  In addition, since the tar produced | generated by carbonaceous raw material pyrolysis is a composite compound, since a composition changes with raw materials, toluene was used as a simulation tar. In this example, toluene, which is an aromatic tar that is more difficult to decompose than a linear hydrocarbon tar, is used as a representative simulated tar. If the tar can be steam reformed, a linear hydrocarbon tar is used. Tar is also considered to be easily steam reformed. Here, water vapor was quantitatively added with water (heated to make water vapor), and carbon in tar was calculated in terms of moles based on carbon in toluene (84 in molecular weight 92 was carbon). The pyrolysis gas and pyrolysis tar 3 generated in the field test described later are accompanied by pyrolysis gas in addition to the pyrolysis tar, and contain trace amounts of hydrocarbons such as methane and ethane. The steam reforming of this hydrocarbon gas is also estimated to occur in parallel, but since it is extremely small, it does not affect the preferred steam / tar carbon molar ratio shown in the present invention (methane, ethane Even in a very large number of systems, the calculation process is necessary because the steam reforming reaction derived from methane, ethane, etc. can be separated from the steam reforming of tar by calculating the material balance of carbon, hydrogen, and oxygen. But it has little effect).

In FIG. 2, the gas yield (mass basis%) after reforming is shown for each catalyst, and components less than 100% are other (H ₂ , C ₂₊ hydrocarbons, nitrogen and measurement error). Become. When tar reacts, it is converted to gas (CO, CH ₄ , CO ₂ etc.), so CO + CH ₄ + CO ₂ (three components from the top) is the reaction product gas, C ₆ H ₆ is decomposed but remains in tar , C ₇ H ₈ is an unreacted substance, and it can be judged that the catalyst characteristic is excellent when CO + CH ₄ + CO ₂ is large. Since toluene is used as a simulated tar in the test of FIG. 2, the total yield of CO + CH ₄ + CO ₂ is defined as the toluene conversion rate (in this case, synonymous with the tar conversion rate). This is because it is difficult to recover tar (toluene) experimentally. In the field test as shown in Example 4, the methylene chloride soluble matter is tar, and the actual tar amount before and after the reaction (unit: g / Nm ³ ). Was measured to obtain a tar conversion rate according to the following formula. Although there is a difference between the calculation based on the production-side substance standard and the calculation based on the remaining raw material standard, it is synonymous in that the mass ratio of raw material tar converted to gas is obtained.

Formula: (actual tar amount before reaction−actual tar amount after reaction) / actual tar amount before reaction × 100 <%>
In FIG. 2 (a) (S / C = 2), the ratio of the gas component (CO + CH ₄ + CO ₂ ) is 85% and 79% for the Co-added and Ni-added catalysts, respectively, compared to the case of no addition, which is similar to the conventional example Excellent catalyst performance (hydrocarbon conversion). Cr and Mn were 65-75% according to it. Cu and Zn had results worse than those without addition. On the other hand, in FIG. 2B (S / C = 5 mol / mol), only Ni protruded and the performance was good, and the catalyst performance exceeded 85%. Therefore, it can be said that Ni can reform tar with a high conversion rate stably without depending on the gas component.
(Example 2)
Next, S / C = 5, and the test was performed under the same conditions as in Example 1 except that the iron ore mass ratio and the nickel mass ratio in the total mass of iron ore, dolomite, and nickel were changed. The effects of mass ratio and nickel mass ratio on the conversion rate were investigated.

  Table 1 shows a characteristic table in which the iron ore mass ratio and the nickel mass ratio in the catalyst are matrixed. A conversion rate of 70% or more is indicated by ◎, a conversion rate of 50% or more and less than 70% is indicated by ○, and a conversion rate of less than 50% is indicated by Δ. ◎ is a catalyst that exhibits sufficient conversion characteristics.

The range that can be evaluated as an excellent catalyst from Table 1 is 30% by mass or more and 70% by mass or less of iron ore and 0.05% by mass or more of nickel. The range of high nickel mass (~ 20 mass%) and low iron ore mass (10-20 mass%) also shows good tar conversion, but the price of metallic nickel is about 600 to 800 times that of iron ore, In the present invention in which an effect is obtained by using an inexpensive iron ore, 4 mass% or less is preferable.
(Example 3)
Next, the iron ore mass ratio in the total mass of iron ore, dolomite, and nickel was 50 mass%, the nickel mass ratio was 1 mass%, and the S / C was changed under the same conditions as in Example 1. Tests were conducted to investigate the effect of S / C on the conversion rate.

  as a result,

Thus, it is considered that S / C is preferably 1 mol / mol or more and 5 mol / mol or less as a preferable tar reforming condition.
Example 4
Next, a field test using actual pyrolysis gas was performed based on the results.

The tar conversion rate (unit%: calculated by the above formula based on the tar content measurement result at the inlet and outlet of the reformer by the constant velocity suction / methylene chloride absorption method) was 92%. The catalyst at this time was 50% by mass of lobe river iron ore, 1% by mass of nickel, and 49% of calcined dolomite. The iron ore powder was impregnated with an aqueous solution of nickel nitrate hexahydrate and dried with a 120 ° C. dryer. After calcination in air at 400 ° C. for 2 hours, the mixture was physically mixed with the calcined dolomite powder, pressed, crushed and sized. The operating conditions are: pyrolysis raw material: waste wood chips (biomass) and coal, 17 tons / day, catalyst layer temperature 900 ° C., inlet tar concentration is 1.6 g / Nm ³ , outlet tar concentration is 0.1 g / It was Nm ^3. The molar ratio of steam and tars in carbon, gas water vapor content before and after reforming furnace (kg / Nm ³⁾ and gas tar (kg / Nm ³⁾ was measured, after the carbon mass% in tar analysis, the amount of water vapor The number of moles divided by 18 was divided by the number of moles obtained by dividing the amount of tar in the gas by the carbon mass in the tar by 12 to obtain a molar ratio. The actual measured value was 4 mol / mol. The tar in the field test is a sampling method in which gas is sucked from the pipe before and after reforming at the same speed as the gas flow, and the component that is soluble in methylene chloride is tar. The result was equivalent to the result. This gas contains 60 to 1,200 ppm of hydrogen sulfide derived from coal (concentration fluctuations are due to fluctuations in operating conditions such as the generation of a large amount of gas at the time of starting materials. The average is 1000 to 1,200 ppm), usually a nickel-containing reforming catalyst However, there was no adverse effect on the catalyst performance. Furthermore, although it is carbon deposition to a catalyst, as a result of analyzing the catalyst after a test, carbon amount is 0.1-0.3 mass% (0-0.1 mass% before a test) and a trace amount, and it is conventional. There was no tendency of catalyst deactivation due to carbon deposition of the iron-based catalyst. In addition, as a catalyst component, although iron ore was changed from 30 mass% to 70 mass% (1 mass% of nickel, the remaining dolomite), the tar conversion rate was a good result exceeding 70% in all cases. . It can be seen that tar reforming is possible without much influence of poisoning by hydrogen sulfide.

It is a typical flowchart of the carbonaceous raw material pyrolysis process based on this invention. It is a figure which shows the comparison result of the tar improvement performance by the difference in a metal kind.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carbonaceous raw material 2 Pyrolysis furnace 3 Pyrolysis gas and pyrolysis tar 4 Carbide 5 Reforming furnace 6 Reforming gas 7 Gas processing apparatus 8 Product gas 9 Gas use process 10 Oxidant 11 Water vapor 12 Reforming catalyst

Claims (6)

  A catalyst used in a tar reforming method for generating a reformed gas mainly composed of carbon monoxide and hydrogen by steam reforming a pyrolysis gas containing tar generated by pyrolysis of a carbonaceous raw material, A tar reforming catalyst comprising a mixture of iron ore, dolomite, and nickel.   2. The tar reforming catalyst according to claim 1, wherein the pyrolysis gas containing tar further contains hydrogen sulfide.   The tar reforming catalyst according to claim 1 or 2, wherein the carbonaceous raw material contains at least one waste of biomass, plastic, or general waste raw material waste. A method for producing a tar reforming catalyst according to any one of claims 1 to 3,
After mixing iron ore and dolomite, impregnating the mixture with a nickel-containing aqueous solution, drying and calcining to produce a tar reforming catalyst,
After impregnating a nickel-containing aqueous solution into iron ore, drying and calcining, dolomite is mixed with the calcined product to produce a tar reforming catalyst.
Or, after impregnating a nickel-containing aqueous solution into dolomite and drying and calcining, the iron reforming is mixed with the calcined product to produce a tar reforming catalyst.   When producing the catalyst, the total mass of the raw iron ore, the raw dolomite, and nickel in the raw nickel-containing aqueous solution, the mass ratio of the raw iron ore is 30 mass% or more and 70 mass% or less, and the 5. The method for producing a tar reforming catalyst according to claim 4, wherein the mass ratio of nickel is 0.05 mass% or more.   A tar steam reforming method using the tar reforming catalyst according to any one of claims 1 to 3, wherein a molar ratio of steam and a carbon in the tar as a reaction raw material for steam reforming is provided. A method for steam reforming of tar, wherein (steam / carbon in tar) is 1 mol / mol or more and 5 mol / mol or less.

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