Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
  • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
  • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
  • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
  • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
  • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
  • B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors

Definitions

• the present invention relates to an iron-based powder for an oxygen reactant and an oxygen reactant using the same.
• Oxygen reactant products that use the reaction between iron-based powder and oxygen are known as oxygen absorbers for preventing quality deterioration due to oxidation in foods and pharmaceuticals, and exothermic agents such as disposable body warmers.
• the iron-based powder used for the oxygen reactant absorbs oxygen present in the atmosphere around the iron-based powder due to the reaction between iron and oxygen to create a hypoxic state. By creating it, it is possible to suppress the activity of insects, bacteria, molds, etc., and to suppress the quality deterioration of foods and medicines by preventing oxidation.
• iron-based powders used in exothermic agents such as warmers generate heat of oxidation through the reaction between iron and oxygen, thereby warming the iron-based powder itself and its surroundings.
• various additives such as activated carbon, sodium chloride, silica powder, wood powder, moisture, and sulfur powder are generally added to the iron-based powder for the purpose of further promoting the reaction with oxygen. are doing.
• Patent Literature 1 describes a low-cost reduced iron powder for oxygen absorbers that has an extremely high oxidation rate, excellent productivity, and a specific surface area of 1.0 m 2 /g or more and an apparent density of 1.0 g/cm. 3 or less, an average particle size of 9.0 ⁇ m or less, a metallic iron content of 45% by weight or less, and an average pore diameter of 20000 ⁇ or less.
• Patent Document 2 describes a deoxidant that has excellent reactivity with oxygen, a high initial oxygen absorption rate, a high bulk density, excellent oxygen absorption per unit volume, and can be effectively used for reactions even inside the particles.
• the iron powder has a pore diameter of 2 ⁇ m or less by mercury intrusion method, a specific surface area of 100 times or more than the external specific surface area calculated from the average particle size of the particles, a bulk density of 3 g/cm 3 or more, and an average particle size of 2 mm or less. and an iron powder having a spongy structure in which spherical particles have pores communicating with the outside are disclosed.
• iron powder contained in a portable heating element and having good heat generation performance by reacting well with oxygen has an average pore diameter of 1.0 nm or less by a nitrogen adsorption method, mesopores (pore diameter 2 nm and less than 50 nm) and micropores (having a pore diameter of 2 nm or less) have a pore volume ratio (micropores/mesopores) of 0.05 or more, and a specific surface area calculated by a nitrogen adsorption method
• the ratio of the specific surface area calculated by the mercury intrusion method is 2.0 or more, the content of metallic iron is 90% by mass or less, the oxygen content is 3.0% by mass or more, and the D50 is 30 to 200 ⁇ m.
• Iron powder is disclosed.
• JP-A-2002-292276 Japanese Patent Application Laid-Open No. 2006-263630 WO2017/082183
• Patent Documents 1 to 3 have limitations in the reactivity between the iron-based powder and oxygen.
• An object of the present invention is to solve the above problems and to provide an iron-based powder for an oxygen reactant capable of obtaining high reactivity with oxygen and an oxygen reactant using the same.
• oxygen in the surrounding atmosphere is dissolved in the water added to the iron-based powder, and the dissolved oxygen reacts with metallic iron.
• the added moisture exists in the particles of the iron-based powder, and part of it evaporates into the atmosphere around the iron-based powder, and is not effectively utilized.
• the inventors focused on the metallic iron content of the iron-based powder and the volume of the pores of the iron-based powder, as described above. It was found that iron-based powders with high reactivity to oxygen can be produced by setting the range of each condition.
• the present invention is based on the above findings, and has the following gist and configuration.
• An iron-based powder for an oxygen reactant having a total of 0.05 cm 3 /g or more per gram of base powder.
• the median value D50 of the particle size from the cumulative volume frequency is 10 ⁇ m or more and 500 ⁇ m or less, and the average diameter of the pores having a diameter of 3 nm to 500 ⁇ m is more than 2.00 ⁇ m and 100.00 ⁇ m or less.
• Iron-based powder for oxygen reactants is 10 ⁇ m or more and 500 ⁇ m or less, and the average diameter of the pores having a diameter of 3 nm to 500 ⁇ m is more than 2.00 ⁇ m and 100.00 ⁇ m or less.
• the present invention by defining respective ranges of the metallic iron content of the iron-based powder and the volume per unit mass of the pores having a predetermined diameter in the iron-based powder, the high oxygen reactivity of iron-based powder can be obtained.
• the iron-based powder for an oxygen reactant of the present invention has a metallic iron content of 70% by mass or more and 100% by mass or less, and further has pores communicating with the outside inside the particles of the iron-based powder.
• the volume of pores with a diameter of 3 nm to 500 ⁇ m (hereinafter also simply referred to as “pore volume”) is 0.05 cm 3 /g or more in total per 1 g of the iron-based powder.
• the iron-based powder for an oxygen reactant of the present invention is excellent in reactivity with oxygen, and thus is suitably used as the oxygen reactant of the present invention. Therefore, the oxygen reactant of the present invention can exhibit the same features and effects as the iron-based powder for oxygen reactant of the present invention.
• Metallic iron content is 70% by mass or more and 100% by mass or less] Since metallic iron reacts with oxygen, the reaction with oxygen is difficult to progress when the metallic iron content in the iron-based powder is low. Therefore, iron-based powders with a high metallic iron content are preferred, and the upper limit of the metallic iron content may be 100% by mass. On the other hand, if the content of metallic iron is less than 70% by mass, the amount of metallic iron that reacts with oxygen will be insufficient, causing a problem that the reaction with oxygen will be difficult to proceed. Therefore, the lower limit of the metallic iron content is set to 70% by mass. A preferable range of metallic iron content is 80% by mass or more and 100% by mass or less, more preferably more than 90% by mass and 100% by mass or less.
• iron-based powder refers to metal powder containing 50% by mass or more of metallic iron.
• the iron-based powder can further contain arbitrary elements such as C, S, O, N, Si, Na, Mg, Ca, etc., in addition to the metallic iron (Fe). Also, the metallic iron content can be measured according to the method described later.
• the present invention defines the pore volume for pores with diameters in the range from 3 nm to 500 ⁇ m.
• the diameter of the pore that defines the pore volume is set to 500 ⁇ m or less.
• pores with a diameter of less than 3 nm cannot sufficiently trap water in which oxygen is dissolved. Therefore, in the present invention, the diameter of the pore that defines the pore volume is set to 3 nm or more.
• the pore volume of pores having a diameter of 3 nm to 500 ⁇ m is set to 0.05 cm 3 /g or more by summing the volume of each pore per 1 g of the iron-based powder.
• the total pore volume is preferably 0.08 cm 3 /g or more, more preferably 0.20 cm 3 /g or more per 1 g of iron-based powder.
• the upper limit of the pore volume is not particularly limited, but is industrially about 2.00 cm 3 /g in total per 1 g of the iron-based powder.
• the pore volume can be measured according to the method described later.
• the median value D50 of the particle size from the cumulative volume frequency is 10 ⁇ m or more and 500 ⁇ m or less
• the median value D50 of the particle size calculated by cumulative volume frequency is preferably 10 ⁇ m or more, and preferably 500 ⁇ m or less. If the D50 is less than 10 ⁇ m, the particles become excessively fine and a large amount of agglomerated powder tends to be generated, and it becomes difficult for moisture to be trapped in the pores of the iron-based powder particles, making it difficult to react with oxygen. There is On the other hand, if the D50 exceeds 500 ⁇ m, the particles tend to be excessively coarse, and the inside of the iron-based powder particles may be difficult to react with oxygen.
• a more preferred D50 has a lower limit of 15 ⁇ m and an upper limit of 300 ⁇ m. D50 can be measured according to the method described later.
• the average diameter of pores with a diameter of 3 nm to 500 ⁇ m is greater than 2.00 ⁇ m and 100.00 ⁇ m or less]
• the average diameter of pores in the range of 3 nm to 500 ⁇ m in diameter (hereinafter also simply referred to as “average pore diameter”) in the iron-based powder for an oxygen reactant of the present invention is preferably larger than 2.00 ⁇ m, and 10.00 ⁇ m or more. is more preferably 100.00 ⁇ m or less. If the average pore diameter is 2.00 ⁇ m or less, the pore diameter becomes excessively small as a whole, making it difficult for the added water to enter the pores, which may hinder the reaction between dissolved oxygen in the water and iron. be.
• the average pore diameter when the average pore diameter is larger than 100.00 ⁇ m, the pore diameter becomes excessively large as a whole, and although the added moisture easily enters the pores, it also becomes easy to evaporate, so the moisture cannot be captured in the pores. may become difficult.
• the average pore diameter can be measured according to the method described later.
• the maximum particle size of the iron-based powder for an oxygen reactant of the present invention is preferably 15 ⁇ m or more, more preferably 20 ⁇ m or more. This is because if the maximum particle size is less than 15 ⁇ m, a large amount of agglomerated powder is likely to occur, making it difficult for moisture to be trapped in the pores of the iron-based powder particles, which may make it difficult to react with oxygen. be.
• the upper limit of the maximum particle size is not particularly limited, it is industrially about 1000 ⁇ m. Also, the maximum particle size of the iron-based powder can be measured according to the method described later.
• the metallic iron content in the iron-based powder can be measured according to JIS A 5011-2 "Method for quantifying metallic iron".
• Average pore diameter (average diameter of pores with a diameter of 3 nm to 500 ⁇ m) and pore volume (total volume of pores with a diameter of 3 nm to 500 ⁇ m per unit mass of iron-based powder) for pores possessed by the iron-based powder can be measured as That is, a mercury intrusion method is applied in which a container containing an iron-based powder sample is evacuated, filled with mercury, pressure is applied to the mercury, and the pores of the iron-based powder particles are filled with mercury to measure the pore volume. .
• the average pore size is calculated, and the representative value of the diameter of each pore having a diameter of 3 nm to 500 ⁇ m (the average fineness referred to herein) pore diameter).
• an apparatus capable of such measurement for example, there is Autopore V9620 manufactured by Shimadzu Corporation-Micromeritics.
• the method of determining the median particle size D50 and the maximum particle size from the cumulative volume frequency of iron-based powders can be calculated and measured as follows.
• the target iron-based powder is put into a solvent (e.g., ethanol), dispersed by ultrasonic vibration for 30 seconds or more, and the particle size is determined by a laser diffraction particle size distribution analyzer using a laser diffraction/scattering method.
• measurement that is, the volume-based particle size distribution of the iron-based powder particles.
• a cumulative particle size distribution is calculated from the obtained particle size distribution, and the median value D50 of the particle size corresponding to 50 % of the total volume of all particles is used as a representative value of the particle size of the iron-based powder.
• the maximum particle size of the iron-based powder means the maximum value of the particle size distribution measured by a laser diffraction particle size distribution analyzer. The measurement conditions are the same as those for D50 .
• iron-based powder In the production of iron-based powders for oxygen reactants, water or gas is sprayed onto molten metal to pulverize and cool and solidify by water atomization method or gas atomization method; iron oxide generated from the surface of steel plate during hot rolling; A method of producing by reducing iron ore powder mined from a mine is preferred. Additionally, the iron-based powder produced may be classified or mixed in various ways to adjust the properties of the iron-based powder.
• the iron-based powder for oxygen reactant according to the present invention can be produced by adjusting the conditions of water atomization or gas atomization. It can also be produced by adjusting the conditions of the pulverization method or the oxide reduction method.
• a preferred example of specific manufacturing conditions is as follows.
• a raw material with a high total iron content is used, or carbon or hydrogen is used as a process for removing oxygen from the iron-based powder. is preferably carried out at a temperature of 750° C. or higher using a tunnel furnace.
• the raw material of the iron-based powder for the oxygen reactant it is preferable to reduce the raw material of the iron-based powder at 770° C. or higher using a tunnel furnace in order to effectively form pores communicating with the outside inside the particles.
• the raw material of the iron-based powder is heated to 800 by using a tunnel furnace. It is preferable to reduce at °C or higher.
• the median particle size D50 In order to adjust the median particle size D50 from the cumulative volume frequency of the iron-based powder for the oxygen reactant to 10 ⁇ m or more, classification by sieving to further remove fines, or iron of each particle size It is preferable to mix and adjust the base powder in a predetermined ratio. On the other hand, in order to adjust the median value D50 to 500 ⁇ m or less, the crushing conditions of the iron-based powder as a raw material are adjusted to further remove coarse particles, or iron-based powders of each particle size are mixed in a predetermined ratio. It is preferable to adjust
• the iron-based powder raw material is reduced at a temperature of 700° C. or higher and reduced for 1 hour. It is preferable to set it as above.
• the average pore diameter it is preferable to subject the raw material of the iron-based powder to impact pulverization with a hammer mill or to adjust the classification conditions with a sieve.
• the metallic iron content and the pore volume per unit mass of the iron-based powder mainly affect the amount of reaction between iron and oxygen, if the pore volume is the same, the reactivity with oxygen is not affected by differences in production methods (pulverization conditions, reduction conditions, etc.).
• the iron-based powder for the oxygen reactant described above can be used as the oxygen reactant.
• the oxygen reactant of the present invention can be obtained by enclosing the iron-based powder for the oxygen reactant of the present invention in a bag described below.
• constituents other than the iron-based powder for the oxygen reactant can be used without any particular limitation as long as they are used in conventionally known oxygen reactants. Examples include a bag made of polyethylene ventilation packaging material, a bag made of paper/perforated polyethylene ventilation packaging material, and the like.
• An iron-based powder for an oxygen reactant to be used in this example was produced by the following procedure.
• a raw material for the iron-based powder (iron ore powder) before reduction is prepared, and the raw material for the iron-based powder is reduced by a reduction method adjusted to various conditions, and 26 types of dried iron-based powders for oxygen reactants are prepared. Powder samples (D 50 : 1-1750 ⁇ m) were obtained.
• the characteristics of the obtained iron-based powder for oxygen reactants were evaluated as follows.
• the apparent density of the iron-based powder was measured according to JIS Z 2504 "Determination of apparent density of metal powder".
• the specific surface area of the iron-based powder is about 5 g of the iron-based powder sample. It was measured by the Kr gas adsorption method using 3Flex manufactured by Micromeritics.
• the metallic iron content of the iron-based powder was measured according to JIS A 5011-2 "Method for quantifying metallic iron".
• the pore distribution of the iron-based powder was measured by mercury intrusion using a pore distribution measuring device (Shimadzu Seisakusho-Micromeritics Autopore V9620).
• the average pore diameter and the pore volume with a diameter of 3 nm to 500 ⁇ m per unit mass of the iron-based powder were calculated according to the above-described method.
• the particle size and volume frequency of the iron-based powder were measured using a laser diffraction particle size distribution analyzer (LA-950V2, manufactured by Horiba, Ltd.), and the iron-based powder was put into ethanol as a solvent and subjected to ultrasonic vibration for 1 minute. was measured after dispersion with Then, the median value D 50 , which is the representative value of the particle size of all the iron-based powder particles, and the maximum particle size of the iron-based powder were calculated from the cumulative volume frequency according to the above-described method.
• the oxygen reaction rate evaluation of the iron-based powder for the oxygen reactant was performed as follows. An aqueous solution prepared by dissolving 0.1 g of sodium chloride powder in 0.3 g of pure water was added to 25 g of each of the 26 types of dry powder samples while mixing to obtain a uniform mixed solution. After that, the mixed solution was vacuum-dried to obtain 26 kinds of iron-based powder samples (I) whose surfaces were coated with sodium chloride. Next, 45 g of pure water was added dropwise to 50 g of diatomaceous earth (CG-1, manufactured by Isolite Kogyo Co., Ltd.) while mixing to uniformly impregnate the diatomaceous earth, thereby obtaining 95 g of water donor (II).
• CG-1 diatomaceous earth
• a breathable packaging material bag structured: nonwoven fabric / perforated polyethylene ) to prepare oxygen reactants to be used in this example.
• each oxygen reactant was sealed in a gas barrier bag (composition: nylon/aluminum foil/polyethylene) together with 3 L of air. After allowing the gas barrier bag to stand at 25° C. for 7 days, the oxygen concentration in the gas barrier bag was measured by gas chromatography (manufactured by Shimadzu Corporation, 2014AT). The oxygen reaction amount was calculated from the difference between the measured oxygen concentration and the oxygen concentration in the air, and the oxygen reaction rate was calculated from the oxygen reaction amount using the following equation (1).
• Oxygen reaction rate (%) ⁇ oxygen reaction amount (mL) / (theoretical oxygen reaction amount (mL) of 1.5 g of metallic iron x metallic iron content of iron-based powder (% by mass)) ⁇ x 100 ⁇ (1)
• the theoretical oxygen reaction amount of 1.5 g of metallic iron means that all 1.5 g of metallic iron (Fe) reacts with oxygen to form ferric oxide (Fe 2 O 3 ). It is the oxygen reaction amount when it becomes, and is about 493 mL (25 ° C.).
• Table 1 shows the results of the oxygen reaction rate of each iron-based powder of Comparative Example, Conventional Example and Invention Example.
• an invention in which the content of metallic iron is 70% by mass or less and 100% by mass or less, and the total volume of pores having a diameter of 3 nm to 500 ⁇ m per unit mass of the iron-based powder is 0.05 cm 3 /g or more.
• the iron-based powders used in Examples 1-14 had an oxygen reaction rate of 10% or more, and were superior to the iron-based powders used in Comparative Examples 1-9 and Conventional Examples 1-3. I understand.
• Invention Examples 6 and 7 have an average pore diameter of more than 2.00 ⁇ m and 100.00 ⁇ m or less, and therefore are superior in the oxygen reaction rate. Furthermore, the metal iron content is 80% by mass or more and 100% by mass or less, the pore volume is 0.08 cm 3 /g or more, the D 50 is 15 ⁇ m or more and 300 ⁇ m or less, the maximum particle size is 20 ⁇ m or more, and the average pore diameter Inventive Examples 8 to 12, in which the particle diameter is greater than 2.00 ⁇ m and 100.00 ⁇ m or less, have an oxygen reaction rate of 70% or more, and are superior as iron-based powders for oxygen reactants.
• the metallic iron content, pore volume, D 50 , D 50 it turns out to be important to properly define the factors of maximum particle size, average pore size, especially the metallic iron content and the pore volume.

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