JP2019051508A - Aldehyde adsorbent and filter body using the same - Google Patents

Abstract

To provide an aldehyde adsorbent controlling kinds and amount of acid for enhancing adsorption performance of aldehyde, further exhibiting more excellent adsorbing performance of aldehyde than prior art while keeping adsorption performance of active charcoal itself by controlling physical properties of active charcoal.SOLUTION: There is provided an aldehyde adsorbent (10) in which a loading liquid (4) containing water (1), 2-amino-2-hydroxymethyl-1,3-propanediol (2), and acids of inorganic acid or inorganic acid (3) is loaded to a carrier active charcoal (5), a BET specific surface area of the carrier active charcoal is 750 to 2100 m/g, the 2-amino-2-hydroxymethyl-1,3-propanediol of 1 to 60 pts.wt. is loaded to 100 pts.wt. of the carrier active charcoal and inorganic acid or organic acid of 0.1 to 16 pts.wt. is loaded to 100 pts.wt. of the carrier active charcoal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an aldehyde adsorbent and a filter body using the same, and more particularly to an aldehyde adsorbent in which an adsorbing component is supported on activated carbon and a filter body incorporating the same.

  The presence of secretions such as sweat, the body odor of the human body itself, the odor derived from cooking during meals, the odor of smoke during smoking, the odor of pets, etc., may increase discomfort for some people. Since living environments such as the interior of a modern house and the interior of a vehicle are closed spaces that are air-conditioned, odor tends to remain in the space. Therefore, it becomes more sensitive to odor.

  The above-mentioned odor is also called a daily odor, and lower fatty acids such as acetic acid and isovaleric acid, ammonia and amines, and aldehydes such as formaldehyde and acetaldehyde are the main causes of odor. For the deodorization, activated carbon has been used as a deodorizing material. Conventionally, aniline has been generally attached to activated carbon in order to increase the adsorption capacity of the odor component of activated carbon (see Patent Document 1).

  However, aniline is often avoided from the viewpoint of performance deterioration, and 2-amino-2-hydroxymethyl-1,3-propanediol is becoming the mainstream as a new additive component. In order to enhance and stabilize the deodorizing effect of the adhering component, a deodorizing agent in which an appropriate amount of acid is blended with the adhering component has been proposed (see Patent Document 2, etc.). Furthermore, processing into sheets, filters, and the like has also been proposed (see Patent Document 3). In particular, 2-amino-2-hydroxymethyl-1,3-propanediol is known to be effective for adsorption of aldehydes.

  Patent Documents 2 and 3 do not aim at direct attachment to activated carbon. Activated carbon is effective in adsorbing multiple types of odor molecules due to its developed pores. Therefore, an efficient activated carbon adsorbent that takes advantage of both adsorption of odor molecules due to chemical bonds of 2-amino-2-hydroxymethyl-1,3-propanediol and trapping in the pores of activated carbon. It has been demanded.

JP 56-53744 A Japanese Patent No. 4590369 JP 2017-127812 A

  In light of such circumstances, the inventor, in particular, balanced the amount of acid to be blended with 2-amino-2-hydroxymethyl-1,3-propanediol, and further by balancing each index of the physical properties of activated carbon, in particular aldehyde. Led to the development of an activated carbon adsorbent that is optimal for deodorization of foods.

  The present invention has been proposed in view of the above situation, and the optimum kind and amount of acid are controlled in order to enhance the adsorption ability of aldehydes of 2-amino-2-hydroxymethyl-1,3-propanediol. Furthermore, by controlling the physical properties of the activated carbon, the present invention provides an aldehyde adsorbent that exhibits an adsorption ability of aldehydes that is superior to that of conventional aldehydes while taking advantage of the adsorption ability of the activated carbon itself, and uses the aldehyde adsorbent. Provide the filter body.

That is, the first invention is an aldehyde adsorbent obtained by adhering an impregnating liquid containing water, 2-amino-2-hydroxymethyl-1,3-propanediol, and an inorganic acid or an organic acid to a carrier activated carbon. The carrier activated carbon has a BET specific surface area of 750 to 2100 m ² / g, and the 2-amino-2-hydroxymethyl-1,3-propanediol is 1 to 60 with respect to 100 parts by weight of the carrier activated carbon. The aldehyde adsorbent is characterized by being adsorbed in parts by weight and adsorbed in an amount of 0.1 to 16 parts by weight of the inorganic acid or organic acid with respect to 100 parts by weight of the supported activated carbon.

  The second invention is the first invention wherein the total pore volume of pores having a pore diameter of 4 to 50 nm is 0.003 to 0.077 mL / g in the measurement of pore distribution of the carrier activated carbon by the DH method. It relates to the aldehyde adsorbent described in 1.

  A third invention relates to the aldehyde adsorbent according to the first invention, wherein the pH buffer capacity of the impregnation liquid represented by the following formula (F) is 290 to 2900 mmol / kg.

  A fourth invention relates to a filter body characterized by holding the aldehyde adsorbent described in the first invention.

According to the aldehyde adsorbent according to the first invention, an impregnation liquid containing water, 2-amino-2-hydroxymethyl-1,3-propanediol, and an inorganic acid or an organic acid is impregnated on the support activated carbon. An aldehyde adsorbent, wherein the carrier activated carbon has a BET specific surface area of 750 to 2100 m ² / g, and the 2-amino-2-hydroxymethyl-1,3-propane with respect to 100 parts by weight of the carrier activated carbon Since the diol is attached in an amount of 1 to 60 parts by weight and the inorganic acid or the organic acid is attached in an amount of 0.1 to 16 parts by weight with respect to 100 parts by weight of the carrier activated carbon, the adsorption ability of the activated carbon itself is utilized. However, it has an excellent ability to adsorb aldehydes.

  According to the aldehyde adsorbent according to the second invention, in the first invention, in the measurement of the pore distribution of the carrier activated carbon by the DH method, the total pore volume of pores having a pore diameter of 4 to 50 nm is 0. Since it is 003-0.077 mL / g, it becomes the range of the pore distribution which can maintain the high adsorption performance of aldehydes.

  According to the aldehyde adsorbent according to the third invention, in the first invention, since the pH buffering capacity of the impregnation liquid represented by the formula (F) is 290 to 2900 mmol / kg, The adsorption performance of aldehydes can be grasped, and the management of the impregnating liquid becomes easy.

  According to the filter body according to the fourth invention, since the aldehyde adsorbent described in the first invention is held, it can be used as a unitized member for adsorbing aldehydes. It is easy to install in a machine, a duct for air supply, etc.

It is a schematic process drawing which shows the manufacture example of the aldehyde adsorbent of this invention. It is a schematic diagram of the filter body using the aldehyde adsorbent of the present invention.

  The aldehyde adsorbent of the present invention is a drug-added activated carbon adsorbent obtained by adhering an impregnating liquid containing a polyhydroxyamine compound mainly exhibiting an aldehyde adsorption effect to carrier activated carbon. That is, the adsorbent has both chemical adsorption of aldehydes by chemicals and physical adsorption by pores developed in activated carbon.

  The aldehyde of the present invention is a concept including all of aldehyde compounds such as formaldehyde, acetaldehyde, propionaldehyde, butanal, pentanal, hexanal, heptanal, octanal, nonanal, and glutaraldehyde. These are substances that cause unpleasant odors, and life odors and body odors are the cause of generation. Of these, the main purpose is efficient adsorption of formaldehyde and acetaldehyde.

  Aldehydes are known to form aldehyde-amine bonds such as Schiff bases with polyhydroxyamine compounds. Thus, through the use of the reaction, aldehydes that cause unpleasant odors are efficiently adsorbed by chemical bonds.

  As the polyhydroxyamine compound, “2-amino-2-hydroxymethyl-1,3-propanediol” is preferable. Another name for this compound is tromethamine or trishydroxymethylaminomethane. As other examples of polyhydroxyamine compounds, 2-amino-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3- Examples include propanediol, 2-amino-2-hydroxyethyl-1,3-propanediol, and the like.

  The reaction between polyhydroxyamine compounds such as 2-amino-2-hydroxymethyl-1,3-propanediol and aldehydes is accelerated as the acidity becomes appropriate. That is, it is conceivable that the acid acts as a catalyst. The acid used here is an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, polyphosphoric acid, and metaphosphoric acid. Examples of the organic acid include carboxylic acids such as succinic acid, fumaric acid, malic acid, malonic acid, maleic acid, and citric acid. In selecting an organic acid, a kind having a low odor is preferable.

  An impregnation liquid is prepared by mixing the polyhydroxyamine compound described above with an inorganic acid or an organic acid. The impregnation liquid is then impregnated with the carrier activated carbon. That is, the activated carbon becomes a base material for attachment. The carrier activated carbon is selected from known activated carbon. The raw materials for the adsorbed activated carbon are coconut husk, large saw dust, sawdust, waste bamboo, coconut husk, palm coconut squeezed, coffee beans squeezed after coffee extraction, coal, petroleum pitch, phenol resin, and the like. After these raw materials are carbonized, activation treatment such as steam activation, zinc chloride activation, phosphoric acid activation, sulfuric acid activation, air activation, carbon dioxide activation, etc. is applied. As a result, pores develop in the activated carbon.

BET specific surface area is a physical property for evaluating the carrier activated carbon. The BET specific surface area of the carrier activated carbon is in a range satisfying 750 to 2100 m ² / g. From the verification of the examples described later, the adsorption performance of aldehydes was lowered when the lower limit of 750 m ² / g was exceeded from the results of adsorption of aldehydes (evaluation by breakthrough time). When it exceeds 2100 m ² / g, the strength of the activated carbon is insufficient, which is not preferable for practical use. Therefore, as a range to ensure good performance, the BET specific surface area is in the range of 750 to 2100 m ² / g.

  Furthermore, in the physical property evaluation of the carrier activated carbon, analysis of the pore distribution of the carrier activated carbon by the DH method (Dollimore-Heal method) is used. The DH method is generally used for analysis of pores having a diameter of 2.0 to 50.0 nm because it can relatively easily grasp distribution analysis of mesopores having a diameter of 2.0 to 50.0 nm. Therefore, in the measurement of the pore distribution of the supported activated carbon by the DH method, the total pore volume of pores having a pore diameter of 4 to 50 nm converges in the range of 0.003 to 0.077 mL / g.

  As is clear from the examples described later, the support activated carbon was measured for pore diameters in various ranges by the DH method, and which range was effective for adsorption was examined. As a result, it has been found that the pore range having a pore diameter of 4 to 50 nm has the most influence on the adsorption performance. Therefore, the total pore volume in the pore diameter range of 4 to 50 nm was evaluated. In the range where the total pore volume is less than 0.003 mL / g, the decrease in the adsorption performance of aldehydes is remarkable, which is not preferable. Moreover, in the range exceeding 0.077 mL / g, the strength of the activated carbon is insufficient, which is not preferable for practical use. For this reason, the total pore volume is defined.

  In addition, the size of the carrier activated carbon, that is, the preferred size of the aldehyde adsorbent is a particle size of approximately 0.5 to 5 mm. Among these, an average particle diameter of 1 to 4 mm is more preferable. The aldehyde adsorbent is exclusively used for adsorption of odor components in the air. For example, it is installed in air cleaners, air conditioners, other air circulation pipes, ducts, and the like. Taking this application into consideration, it is desired to ensure smooth circulation without excessively increasing the pressure loss of the air circulation.

  Therefore, too fine activated carbon such as powdered activated carbon tends to be unsuitable. Therefore, a size of 0.5 to 5 mm, particularly 1 to 4 mm is suitable as the activated carbon having relatively large grains. When the average particle size is less than 1 mm, the activated carbon is densified at the time of filling and the air permeability is lowered. In the case of activated carbon having an average particle size exceeding 4 mm, the surface area per weight is reduced, the amount of polyhydroxyamine compound is reduced, and the adsorption ability of desired aldehydes is hardly exhibited. Therefore, the above range is preferable.

  Next, production of the aldehyde adsorbent of the present invention will be described using the schematic process diagram of FIG. Inorganic or organic acids are weighed and dissolved in water. The amount of water is adjusted according to the amount of carrier activated carbon to be attached. Then, a polyhydroxyamine compound such as 2-amino-2-hydroxymethyl-1,3-propanediol is dissolved therein. In this way, the impregnation liquid is prepared.

  The carrier activated carbon is dried in an absolutely dry state by a dryer or the like. Then, the prepared additive solution is dropped, immersed, etc. on the carrier activated carbon and uniformly adhered to the surface. In addition to this method, spray coating or the like is possible. Then, it dries suitably and the excess water | moisture content in an attachment liquid is evaporated. Thus, the aldehyde adsorbent is completed.

  Here, the addition ratio of 2-amino-2-hydroxymethyl-1,3-propanediol and inorganic acid or organic acid in the aldehyde adsorbent is defined based on the weight of the carrier activated carbon.

  Specifically, 2-amino-2-hydroxymethyl-1,3-propanediol is added in an amount of 1 to 60 parts by weight with respect to 100 parts by weight of the carrier activated carbon. When the amount of the polyhydroxyamine compound is less than 1 part by weight, the amount of aldehydes is not exhibited because it is less than the original. Conversely, when the amount exceeds 60 parts by weight, it is difficult to adjust the impregnating liquid. This amount was the same even when the amount of acids was changed. Accordingly, 2-amino-2-hydroxymethyl-1,3-propanediol is defined as the amount of addition.

  Next, the amount of the inorganic acid or organic acid is 0.1 to 16 parts by weight with respect to 100 parts by weight of the carrier activated carbon. It has been found that the range is suitable even when the amount of 2-amino-2-hydroxymethyl-1,3-propanediol and the type of acid are changed. When the amount is less than 0.1 part by weight, the adsorption efficiency is substantially the same as when no acid is present. This is because when the amount exceeds 16 parts by weight, the binding of aldehydes is inhibited by the excessive amount of acid.

  The conditions for adsorbing liquid to adsorb aldehydes depend on pH. In particular, good adsorption performance is easily obtained under basic conditions. Acids also act as a catalyst and promote the formation of aldehyde-amine bonds. Also from this, an inorganic acid or an organic acid is added according to the above-mentioned prescribed amount. In addition, the preferred acid-base balance in the entire impregnation solution is determined through the pH buffering capacity. By using the value of the pH buffering capacity as an index, it becomes possible to grasp the optimum amount of acids when the amount of 2-amino-2-hydroxymethyl-1,3-propanediol in the impregnating solution is increased or decreased. . In general, the preparation of the impregnation liquid becomes easy.

  The pH buffering ability of the impregnation liquid is expressed as the above formula (F). The impregnating solution itself is essentially in the basic pH range. If hydrochloric acid is added there, the pH shifts to the acidic range beyond neutrality. The properties of the impregnating liquid can be grasped through the amount of hydrochloric acid at this time. In the acidic region where the pH of the impregnating solution is less than 5.0, the adsorption performance of aldehydes decreases. Conversely, even if the acid is added excessively, it is considered that the adsorption performance of aldehydes is ensured until the impregnating solution reaches pH 5.0. Therefore, “in order to adjust the pH to 5.0” in the formula means a limit on the performance of adsorption of aldehydes in the impregnating solution.

  The pH buffer capacity represented by the formula (F) is in the range of 290 to 3000 mmol / kg, more preferably in the range of 290 to 2900 mmol / kg. When the pH buffering capacity is lower than 290 mmol / kg, the adsorption performance of aldehydes when finished into an aldehyde adsorbent is lowered. Further, when the pH buffer capacity exceeds 2900 mmol / kg, the adsorption performance is lowered because of excessive addition to the activated carbon. Since the pH buffering ability of the additive solution can be grasped through titration, the performance and quality of the additive solution can be easily managed.

  Patent document 2 (Japanese Patent No. 4590369) presented in the background art also shows pH buffering capacity and discloses a range of 0.3 to 300 mmol / kg. However, it is greatly different from the range of the pH buffering capacity of the present invention. In particular, in the present invention, it is a property in which the impregnating liquid is strengthened to the more basic side. Japanese Patent No. 4590369 presented in the background art is exclusively used as a spraying liquid. On the other hand, as described above, the present invention is processed up to the aldehyde adsorbent by impregnating the impregnating liquid onto the carrier activated carbon. In general, there are acidic or basic functional groups (residues) on the surface of activated carbon.

  The difference in pH buffering capacity between the two is probably due to the presence of functional groups on the activated carbon surface. The impregnation liquid was not prepared to shift to the basic side from the beginning, but the results of good prototype examples were collected, and a pH buffering capacity in the range of 290 to 2900 mmol / kg was derived. Thus, it is considered that the range of the pH buffer capacity of the present invention and that of Japanese Patent No. 4590369 are different from each other due to differences in processing during the process.

  The aldehyde adsorbent obtained by a series of explanations has already been completed by itself, and is used in various devices for air purification. For example, utilization as the filter body 20 of FIG. 2 is also possible. The filter body 20 includes a rectangular frame portion 21 and front and rear ventilation portions 22. The completed aldehyde adsorbent 10 is poured into the frame portion 21 from the inlet 23, and the inside of the frame portion 21 is filled with the aldehyde adsorbent 10. Later, the inlet 23 is sealed. The filter body 20 can be used as a unitized member. Therefore, installation in an air conditioner, an air purifier, a duct for air supply, or the like becomes easy.

  For example, after operating the apparatus for a certain time, the filter body 20 is removed from the apparatus, and a new filter body 20 is newly installed. Then, the aldehyde adsorbent 10 inside the filter body 20 is extracted and replaced with a new unused aldehyde adsorbent 10. In this case, the filter body 20 can be designed in accordance with the structure of the device to be installed, and it is only necessary to refill the aldehyde adsorbent 10 filled therein. As a result, it is sufficient to replace the consumables. Of course, the filter body has various shapes such as a cylindrical body in addition to the illustrated rectangle, and an optimum size and shape are selected according to the application, purpose, processing capacity, and the like.

[Raw materials]
When specifying the physical properties of the carrier activated carbon, the activated conditions derived from the coconut shell were used to control the activation conditions, so that the BET specific surface area, pore volume, etc. were made differently and sieved to prepare the particle sizes (activated carbon Ac1 to Ac6).
In the subsequent production of the aldehyde adsorbent, “HC-30E” (manufactured by Tsurumi Co.) (activated carbon Ac7) and “HC-16” (manufactured by Tsurumi Co.) (activated carbon Ac8) were used.

  The particle size of the activated carbon was changed depending on the content of the breakthrough test in the evaluation of adsorption performance of aldehydes described later. Test No. 1 and test no. In No. 3, the activated carbon Ac1 to Ac5 and Ac7 had a particle size of approximately 1.7 to 2 mm by sieving. Test No. In No. 2, activated carbon Ac6 to Ac8 was similarly sieved to a particle size of about 1.18 to 1.4 mm.

  As the polyhydroxyamine compound, “2-amino-2-hydroxymethyl-1,3-propanediol” was used (hereinafter, the substance is abbreviated as “AHMPD”).

The following five types were used as inorganic acids.
Phosphoric acid (orthophosphoric acid): NYLEX SPECIALTY CHEMICALS SDN BHD, 89% purity
Hydrochloric acid: manufactured by Kanto Chemical Co., Ltd., special grade, purity 36.7%
Sulfuric acid: manufactured by Kanto Chemical Co., Ltd., deer first grade, purity 96.3%
Polyphosphoric acid: manufactured by Acros Organics, purity 85.4% (as P ₂ O ₅ )
Metaphosphoric acid: manufactured by Kanto Chemical Co., Inc., deer special grade, purity 42.7% (as HPO ₃ )

The following two types were used as organic acids.
Citric acid: manufactured by Kanto Chemical Co., Inc., deer special grade, purity 99.8%
Succinic acid: manufactured by Kanto Chemical Co., Inc., deer special grade, purity 99.8%

[Production of aldehyde adsorbent]
In the production of the aldehyde adsorbent for each prototype, the amount of raw material added was in parts by weight in the table below. The relative amount is based on 100 parts by weight of activated carbon. “Parts” in the table are synonymous with parts by weight. First, acids were weighed and dissolved in water to obtain an acid solution. A weighed 2-amino-2-hydroxymethyl-1,3-propanediol (AHMPD) was added to this acid solution and dissolved to prepare an adhesion solution corresponding to each prototype. The carrier activated carbon was dried and completely dried prior to the addition of the addition solution.

  The carrier activated carbon was weighed and stirred while dropping the adhering solution thereto to homogenize the whole. Then, it dried and produced the aldehyde adsorbent corresponding to each prototype.

[Measurement of physical properties of supported activated carbon]
The specific surface area (m ² / g) is obtained by measuring the nitrogen adsorption isotherm at 77K using an automatic specific surface area / pore distribution measuring device “BELSORP-miniII” manufactured by Microtrack Bell Co., Ltd., and obtained by the BET method. (BET specific surface area).

For the total pore volume (mL / g), the amount of nitrogen adsorbed (V) at a relative pressure of 0.990 was calculated by the following formula (i) using the apparatus used for measuring the specific surface area and applying the Gurvitsch law. ) And converted to the volume (V _p ) of liquid nitrogen. In Equation (i), M _g is the molecular weight of the adsorbate (nitrogen: 28.020), and ρ _g (g / cm ³ ) is the density of the adsorbate (nitrogen: 0.808).

The average pore diameter (nm) is calculated by using the pore volume (mL / g) and specific surface area (m ² / g) values obtained from the above-mentioned measurement, assuming that the shape of the pore is cylindrical. Obtained from ii).

  The value of the pore volume in the pore diameter range of 2 to 200 nm was analyzed by the DH method from the adsorption isotherm of nitrogen gas. From the analysis result of the DH method, the total pore volume of pores having a pore diameter of 2.0 nm or less was determined. Similarly, the total pore volume of pores having a pore diameter of 2.0 to 4.0 nm, pores of 4.0 to 50.0 nm, and pores of 50.0 to 100.0 nm was determined. And the ratio (%) which the total pore volume for each range of pores occupies in the total pore volume was also calculated.

  The benzene adsorption capacity (%) of the carrier activated carbon (before loading, only activated carbon), the benzene adsorption capacity (%) of the aldehyde adsorbent (after loading), packing density (g / mL), and pH are JIS K 1474 ( 2014). The benzene adsorption power was adopted as an index for evaluating general adsorption ability provided as activated carbon.

[Measurement of pH buffering capacity]
The impregnation liquid (50 g) of each prototype was dispensed into a conical beaker, and 1.0 mol / L (1N) hydrochloric acid was added dropwise thereto using a burette. Hydrochloric acid was added dropwise while measuring the pH of the solution, and the amount of hydrochloric acid added when the pH reached 5.0 was read. Then, according to the above formula (F), “the titration amount of hydrochloric acid aqueous solution (mL) required to bring the pH of the impregnating solution to 5.0” is divided by “amount of impregnating solution (kg)”. The pH buffering capacity (mmol / kg) of the impregnating solution of each prototype was calculated by multiplying by “the concentration of hydrochloric acid aqueous solution (mol / L)”.

[Adsorption performance evaluation of aldehydes]
Regarding the aldehyde adsorbents of each prototype, the acetaldehyde adsorption performance was evaluated by a breakthrough test. In addition, as an evaluation of other aldehydes, the adsorption performance of formaldehyde was also evaluated by a breakthrough test. Table 1 shows the test conditions. “C” was the outlet concentration, “C ₀ ” was the inlet concentration, and when “C / C ₀ = 0.1” was reached, it was regarded as breakthrough. That is, when the outlet concentration reached “1/10” of the inlet concentration, the breakthrough was determined. The time from the start of gas inflow to breakthrough was defined as breakthrough time. The concentration of aldehydes was evaluated using a gas detector tube. All detector tube numbers in the table are manufactured by Gastec Corporation.

[Physical properties of supported activated carbon]
The following six types of activated carbon derived from coconut shells were prepared (activated carbon Ac1 to Ac6) in order to verify the physical properties that the carrier activated carbon that is the carrier (base material) of the aldehyde adsorbent should have. Further, activated carbon Ac7 (manufactured by Tsurumi Co., Ltd., product name: “HC-30E”) and activated carbon Ac8 (manufactured by Tsurumi Co., Ltd., product name: “HC-16”) having approximate BET specific surface area and pore distribution were prepared. Activated carbon Ac1 to Ac8 was used as carrier activated carbon. And using activated carbon Ac1 thru | or Ac8, AHMPD (2-amino- 2-hydroxymethyl- 1, 3- propanediol) of Table 2 and 3, phosphoric acid, and water are selected, and the above-mentioned aldehyde adsorbent of It produced according to preparation and the aldehyde adsorbent of prototype example 1-1 thru | or 1-8 was obtained. The amounts of AHMPD and phosphoric acid were common. Tables 2 and 3 show the results of the activated carbon Ac1 to Ac8 and the aldehyde adsorbents of prototype examples 1-1 to 1-8.

In Tables 2 and 3, activated carbon benzene adsorption power (%), BET specific surface area (m ² / g), average pore diameter (nm), total pore volume (mL / g), and each pore diameter of DH method The total pore volume (mL / g) and the ratio (%) are the measurement results of activated carbon Ac1 to Ac8 alone. Furthermore, the breakthrough time (min) of the activated carbon alone was measured.

  In Tables 2 and 3, all of AHMPD, phosphoric acid, and water are relative parts by weight when the carrier activated carbon is 100 parts by weight. The packing density (g / mL), pH, benzene adsorption power (%), and breakthrough time (min) are the measurement results of the aldehyde adsorbents of prototype examples 1-1 to 1-8. The adsorption target for the breakthrough time measurement of each activated carbon alone and prototype examples 1-1 to 1-8 was “acetaldehyde” (Test No. 1). In the table, “ND” is below the measurement limit, and “−” is not measured.

[Consideration of physical properties of supported activated carbon]
In comparison between the carrier activated carbon Ac1 and the prototype 1-1 in which the impregnation liquid was impregnated, the breakthrough time of the carrier activated carbon alone without the addition was good. That is, it is considered that the adsorption by only the pores of the activated carbon exceeded the performance of the impregnating solution. However, the carrier activated carbon alone lost improvement in breakthrough time against the increase in BET specific surface area. On the other hand, the breakthrough time was remarkably improved as in prototype examples 1-2 to 1-6 of the aldehyde adsorbent. Therefore, the range showing good adsorption performance was determined from the transition of breakthrough time for the BET specific surface area. As a result, 750 to 2100 m ² / g is a desirable range.

  The BET specific surface area increased in the order of carrier activated carbon Ac1 to Ac6. In conjunction with this, the benzene adsorption power also increased with the same tendency. From this tendency, it was considered that the performance of breakthrough time was also improved in the order of prototypes. However, contrary to expectations, the breakthrough time of Prototype Example 1-5 was lower than that of Prototype Example 1-4. From this tendency, it was proved that effective adsorption performance (breakthrough time) could not be obtained by evaluating the physical properties of activated carbon only by the BET specific surface area. Therefore, in order to grasp the physical properties of the activated carbon more accurately, a pore distribution by the DH method was added.

  The range of pore diameters of 4 to 50 nm was focused on as the range in which the transition of the total pore volume and the expression of breakthrough performance in each pore diameter category in the measurement by the DH method were clarified. From the results of prototypes in the same range, the total pore volume with a pore diameter of 4 to 50 nm is in the range of 0.002 to 0.080 mL / g, more preferably in the range of 0.003 to 0.077 mL / g. is there.

[AHMPD attachment amount]
Next, using the above-mentioned carrier activated carbon Ac4 and Ac5, while changing the amount of AHMPD (2-amino-2-hydroxymethyl-1,3-propanediol) attached, trial production examples 2-1 to aldehydes 2-5 was produced. Table 4 shows the results of the prototype. The order is the same as in Table 2 above. The adsorption target for breakthrough time measurement was “acetaldehyde” (Test No. 1).

  Then, using activated carbon Ac6, Ac7 and Ac8, and similarly changing the amount of AHMPD (2-amino-2-hydroxymethyl-1,3-propanediol) attached, trial production examples 2-6 to 2-20 was produced. The adsorption target for breakthrough time measurement was “formaldehyde” (Test No. 2). Tables 5 to 7 show the results of prototype examples. In Tables 5 to 7, AHMPD, phosphoric acid, and water are all expressed in relative parts by weight when the carrier activated carbon is 100 parts by weight. The packing density (g / mL), pH, benzene adsorption power (%), and breakthrough time (min) are the measurement results of the aldehyde adsorbents in Prototype Examples 2-6 to 2-20. In some prototypes, the pH buffering capacity of the impregnating solution was measured. In the table, “−” means not measured.

[Consideration of AHMPD deposition amount]
Prototype Examples 2-4 and 2-5 and Prototype Examples 2-6 to 2-8 are examples using the same carrier activated carbon and different amounts of AHMPD. From this tendency, the adsorption performance of acetaldehyde or formaldehyde improved as the amount of AHMPD added increased. Prototype examples 2-1 to 2-3 are also examples in which the same carrier activated carbon is used. However, in this case, the amount of AHMPD added and the adsorption performance of acetaldehyde were not simply proportional, and the adsorption performance was lowered in prototype 2-3. Prototype Examples 2-14 to 2-20 are also examples using the same carrier activated carbon. Similarly, the amount of AHMPD added and the adsorption performance of formaldehyde are not simply proportional, and the adsorption performance was lowered in Prototype Example 2-20. The same is true for Prototype Examples 2-9 to 2-13, and the adsorption performance was lowered in Prototype Example 2-13. From this, it was determined that there is an optimum AHMPD attachment range for each carrier activated carbon having a different BET specific surface area. Further, from the results of Prototype Example 2-8, it is considered that the upper limit of the amount of AHMPD attached is 60 parts by weight.

  Furthermore, “relation between the amount of AHMPD added and the amount of acid”, “expansion of types of acids”, and “expansion of types of aldehydes” were repeatedly verified. The subsequent production of all prototypes was the same as the method for producing the aldehyde adsorbent described above except for the selection of activated carbon, and only the amount and type were changed. In each table after Table 8, pH, packing density, and benzene adsorption power are all the results of measurement of the prototype aldehyde adsorbent. In some prototypes, the pH buffering capacity of the impregnating solution was measured.

[Relationship between AHMPD deposition amount and acid amount]
Using support activated carbon Ac7, the amount of AHMPD attached was appropriately selected and fixed, and prototypes 3-1 to 3-17 were produced while changing the amount of acid (phosphoric acid) correspondingly. The target of the adsorption test is “acetaldehyde” (Test No. 1). Prototype examples 4-1 to 4-6 and 5-1 to 5-5 were prepared in which the acid amount was fixed and the amount of AHMPD attached was changed. The results are Tables 8-13.

  Then, the activated carbon Ac8 was used, and the amount of AHMPD was fixed, and prototype examples 6-1 to 6-7 were produced while changing the amount of acid (phosphoric acid). The object of the adsorption test is “formaldehyde” (test No. 2). The results are Tables 14 and 15.

[Consideration of AHMPD Amount and Acid Amount]
As can be seen from Table 13, the trial examples 5-1 to 5-5 produced without using any acid (phosphoric acid) had a breakthrough time that was proportional to the amount of AHMPD. Obviously, it is the manifestation of the adsorption capacity solely due to AHMPD. In this case, in order to obtain good adsorption performance, the amount of AHMPD must be considerably increased, which is not efficient. Moreover, since the benzene adsorption power decreases with an increase in the amount of AHMPD, the decrease in the adsorption capacity other than acetaldehyde is remarkable, which is not preferable. Therefore, the non-addition of acids is not effective from the viewpoint of maintaining the performance as an adsorbent.

  Prototype examples 3-1 to 3-17 disclosed in Tables 8 to 11 are the results of changing the acids (using phosphoric acid) while fixing the amount of AHMPD in three stages. First, prototype examples 3-1 to 3-8 are production examples in which the phosphoric acid acid was changed from no addition to 6.5 parts (relative amount). Since the breakthrough time was extended from Prototype Examples 3-1 to 3-5, the adsorption efficiency of acetaldehyde was increased. However, according to the results of Prototype Examples 3-6 to 3-8, the adsorption efficiency of acetaldehyde decreased. Therefore, it was determined that there is an upper limit for the addition of acids.

  Prototype Examples 3-9 to 3-12 are production examples in which the acid phosphoric acid was changed from no addition to 4.0 parts (relative amount), and Prototype Examples 3-13 to 3-17 represent acid phosphates. In this example, the amount was changed from no addition to 6.0 parts (relative amount). In any case, the tendency was the same as described above, and according to the results of Prototype Examples 3-15 to 3-17, the adsorption efficiency of acetaldehyde decreased.

  Prototype examples 6-1 to 6-7 use activated carbon Ac8, the amount of AHMPD is fixed to 20.0 parts, and the phosphoric acid acid is changed from no addition to 16.0 parts (relative amount). It is. From trial example 6-2 to 6-6, the breakthrough time was longer than in additive-free trial example 1, and thus the adsorption efficiency of formaldehyde was increased. From the results of Prototype Example 6-7, the adsorption efficiency of formaldehyde was lowered when the amount of acid added was too large as in the past.

  From a series of results, the adsorption performance of acetaldehyde shows that even if acids are added to 4 parts by weight or more, the adsorbed amount of acids tends to decrease from 4 parts by weight regardless of variation in the amount of AHMPD Therefore, it was concluded that the upper limit of acids was approximately 16 parts by weight. About the minimum, it was set as 0.1 weight part from Prototype Example 3-2.

  Prototype examples 4-1 to 4-6 disclosed in Table 12 are the results of changing the amount of AHMPD while fixing the amount of acids (phosphoric acid). Compared to the results shown in Table 13, the breakthrough time was significantly extended with the addition of acids. From this result, it can be said that addition of acids is essential.

[Expansion of acid types]
Using the activated carbon Ac7 and increasing the types of inorganic and organic acids used as acids, a prototype example of an aldehyde adsorbent was prepared. Table 16 shows hydrochloric acid (prototype example 7-1) and sulfuric acid (prototype examples 8-1 to 8-5), and Table 17 shows citric acid (prototype examples 9-1 to 9-3) and succinic acid (prototype example 10). -1,10-2), Table 18 is polyphosphoric acid (prototype examples 11-1 to 11-6), and Table 19 is metaphosphoric acid (prototype examples 12-1 to 12-6). The target of the adsorption test is “acetaldehyde” (Test No. 1).

[Consideration of extended types of acids]
As in each prototype, the production of the acids changed to other inorganic acids and organic acids was also effective for acetaldehyde adsorption. However, since sulfuric acid is a strong acid, it is considered that the degradation of AHMPD is stronger than the action as a catalyst and the performance is lowered. Therefore, in Prototype Examples 8-4 and 8-5, the performance degradation of breakthrough time was remarkable. Furthermore, even when the type of phosphoric acid was changed, the trend between the amount of acids and breakthrough time was similar.

[Expanding types of aldehydes]
So far, the performance of aldehyde adsorbents has been evaluated by the breakthrough time of acetaldehyde and formaldehyde. Here, in the same prototype, it was verified that the breakthrough time of acetaldehyde (Test No. 1) and formaldehyde (Test No. 3) was also measured, thereby being effective for adsorption of aldehydes. Prototype examples 13-1 to 13-3 in Table 20 correspond to the above-described prototype examples 3-3, 3-10, and 3-14 in this order.

[Consideration of extended types of aldehydes]
Although there was a difference in breakthrough time depending on the type of aldehydes, it was confirmed that acetaldehyde and formaldehyde had a similar trend. Therefore, it was convinced that it was also effective for the adsorption of other aldehydes.

[Consideration of pH buffering capacity]
In some of the prototype examples, the pH buffering ability of the impregnating solution used for production was also measured for some examples where the acetaldehyde adsorption performance (breakthrough time) was good. From this result, the range of 290 to 2900 mmol / kg was considered appropriate when the numerical range of pH buffer capacity was summarized. By prescribing the range, it is possible to grasp the properties and the like of the prepared impregnating liquid, and the convenience is enhanced.

[Summary]
From the production results and verification results of the aldehyde adsorbents of each prototype, an impregnation liquid prepared from water, AHMPD (2-amino-2-hydroxymethyl-1,3-propanediol), and acids is impregnated on the carrier activated carbon In the adsorbent prepared as described above, the BET specific surface area required for the carrier activated carbon and the pore distribution by the DH method could be defined. Moreover, the amount of AHMPD and acids in the impregnating solution, and also the pH buffering capacity could be specified. By integrating these indices, it was possible to obtain the above-mentioned prototypical aldehyde adsorbent. From this knowledge, the performance of the aldehyde adsorbent can be utilized to develop the filter body holding it. In this way, it can be a product with increased handling convenience.

  The aldehyde adsorbent of the present invention can be produced at low cost because the adsorbent is combined with activated carbon, and it is an extremely efficient adsorbent with both adsorption of aldehydes with the adsorbent and general adsorption with activated carbon. . Therefore, it is promising for air purification in closed environments such as indoors, hospitals, cars, cabins, and ships. Furthermore, since it can be easily processed into a filter body, the convenience of handling is improved and the application to air conditioning equipment is easy.

1 water 2 polyhydroxyamine compound (2-amino-2-hydroxymethyl-1,3-propanediol)
3 acids (inorganic or organic acids)
4 Adsorbing liquid 5 Activated carbon carrier 10 Aldehyde adsorbent 20 Filter body 21 Frame part 22 Vent part 23 Inlet

Claims (4)

An aldehyde adsorbent obtained by adsorbing water, 2-amino-2-hydroxymethyl-1,3-propanediol, and an impregnation liquid containing an inorganic acid or an organic acid on a carrier activated carbon,
The carrier activated carbon has a BET specific surface area of 750 to 2100 m ² / g;
1 to 60 parts by weight of the 2-amino-2-hydroxymethyl-1,3-propanediol is attached to 100 parts by weight of the carrier activated carbon, and
The aldehyde adsorbent characterized in that 0.1 to 16 parts by weight of the inorganic acid or organic acid is attached to 100 parts by weight of the carrier activated carbon.   2. The aldehyde adsorbent according to claim 1, wherein a total pore volume of pores having a pore diameter of 4 to 50 nm is 0.003 to 0.077 mL / g in measurement of pore distribution of the support activated carbon by a DH method. . 2. The aldehyde adsorbent according to claim 1, wherein a pH buffer capacity of the impregnating solution represented by the following formula (F) is 290 to 2900 mmol / kg.

  A filter body comprising the aldehyde adsorbent according to claim 1.

Images