Classifications

• • 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
  • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

• the present invention relates to a volatile organic compound (hereinafter referred to as VOC) gas adsorbent and a method for producing the same. More specifically, the present invention relates to a pressure swing adsorption (PSA) method.
• PSA pressure swing adsorption
• the present invention relates to an adsorbent that is optimal as an adsorbent when recovering C gas, and a method for producing the same.
• the adsorbent for V 0 C gas of the present invention is suitable as an adsorbent for recovering VOC gas in the air in a gasoline stand or an oil depot by the PSA method.
• the present invention relates to a method for recovering hydrocarbons from waste gas or the like containing gaseous hydrocarbons by adsorption, easily and efficiently using cooling and concentration.
• VOC volatile organic compounds
• VOCs in air react with oxygen to cause photochemical smog when exposed to ultraviolet light, even at low concentrations (general term for oxidizing substances such as ozone and peroxides). Is generated.
• the generated ozone reacts with nitrogen oxides (NO x) and sulfur oxides (SO x) to produce nitric acid and sulfuric acid, which cause acid rain.
• NO x nitrogen oxides
• SO x sulfur oxides
• the conventional V0C recovery technology is a painting factory of an automobile manufacturer, a large-scale printing factory of a major printing company, etc., from the viewpoint of improving the working environment in the factory and preventing odors in the neighborhood.
• a combustion device such as a catalytic combustion device is installed in the country, it is limited to cases where the amount of exhaust gas containing V 0 C is large. Therefore, it is not realistic to adopt such a combustion device in a general business establishment from the viewpoint of air quality conservation.
• emissions from small-scale general V 0 C emission sources such as gasoline stands, fuel oil shipping facilities, oil depots, cleaning and painting industries, etc. There is a strong demand for the development of a practical technology for recovering V 0 C.
• the recovery system using the pressure fluctuation adsorption separation method has been attracting attention as a suitable process for VOC recovery because it requires only a small device and is easy to operate and maintain.
• PSA pressure fluctuation adsorption separation method
• VOC-recovered gas emitted from general VOC emission sources such as gasoline stands, oil depots, and fuel oil shipping facilities
• the concentration may fluctuate, it is also important to consider those fluctuation factors in order to efficiently recover VOCs by the PSA method.
• V 0 C molecules that are easily released into the atmosphere in other words, V 0 c molecules with a higher vapor pressure tend to have a smaller molecular size, and such molecules are condensed by capillary in the small pores of the adsorbent. It is considered that it is relatively easily adsorbed.
• activated carbon has a specific surface area 1 0 0 0 m 2 Zg or more high surface area and have small pores (micro pore), but is also excellent moisture resistance, air and VO C molecule combustible Safety concerns have been pointed out due to contact with activated carbon, a volatile substance, and it is not practical to use it for VOC recovery equipment in Japan.
• noncombustible adsorbent inorganic noncombustible Of adsorbent
• Activated carbon is a typical sorbent is to have a 1 0 0 0 m large specific surface area of more than 2 Z g, if you look at only the adsorption capacity, an optimum adsorbent as an adsorbent for VO C.
• activated carbon is flammable, it is safe to use it as an adsorbent for a V0C adsorption device by the PSA method in gasoline stands or oil depots where flammable gas is handled. It is difficult to use in terms of management.
• inorganic oxide adsorbents such as zeolite are attracting attention as non-flammable adsorbents, and the pressure and temperature swing adsorption (PTSA) method, which has almost the same adsorption principle as the PSA method, There is an example that has been tried by the temperature swing adsorption (TSA) method.
• PTSA pressure and temperature swing adsorption
• VOCs are hardly adsorbed due to their low concentration
• saturated water vapor affects the adsorption of VOCs.
• Zeorai DOO although the specific surface area is large, express acidity due to low ratios (Si0 2 / Al 2 0 3 ) of the silica mosquitoes and alumina, the higher the affinity for water, water Is selectively adsorbed.
• silica mosquito silica, S i 0 2 itself, strong shows water repellency, usually, on the surface of the silica force indicating the high surface area hydrophilic silanol (S i - OH) groups Many remain.
• zeolites have a surface area of around 500 m 2 Zg, which is a class of large surface area among inorganic non-combustible adsorbents.
• silica mosquito alumina ratio for (Si0 2 / Al 2 0 3 ratio) is low, acidity by alumina is expressed high affinity with water, a problem of selectively adsorbing the moisture in the air .
• zeolite is dealuminized without causing crystal destruction by treatment such as acid extraction, and is made hydrophobic so that physical properties such as specific surface area are not impaired as much as possible.
• treatment such as acid extraction
• silica dim Si0 2 on the surface hydrophilic groups (silanol groups: SiOH) is Due to their presence, they have extremely high water absorption, meaning that silica gel cannot be used directly as a VOC-PSA adsorbent.
• the silica gel can be almost completely hydrophobized, but the physical properties related to the adsorption capacity such as the specific surface area are significantly reduced.
• the VOC adsorption amount is small, and The higher the filling amount, the higher the adsorbent cost.
• the water-sparing agent, galine-based organic compound is expensive and harmful volatile compound, so care must be taken to handle it. Has safety issues.
• one of the particular problems as a fixed source of gaseous hydrocarbons is a tanker that stores and unloads volatile hydrocarbons on a single tanker of a storage tanker or on a coastal vessel.
• the waste gas generated at this time contains a relatively high concentration of hydrocarbons of 10 to 30%.
• the other is gaseous hydrocarbons generated from solvents used in painting facilities and printing facilities, etc., whose concentration is relatively low at tens to thousands of ppm.
• absorption and absorption methods using absorbents have been widely used for high concentrations, and adsorption methods for low concentrations. I have.
• activated carbon or zeolite is used as the adsorbent in the adsorption method.
• the adsorption method examples include a fixed bed method and a fluidized bed method from the viewpoint of the apparatus.
• the method (apparatus) for treating and recovering the released gas containing gaseous hydrocarbons (solvents) using a fixed-bed method includes the TSA method, the PSA method, and the PTS combining both methods.
• Method A is used, depending on the type of solvent and recovery conditions.
• steam is directly passed through an adsorption layer saturated with a solvent to raise the temperature, and a wet TSA method for desorption is used, and a small amount of desorbed gas is heated without using steam at the time of desorption to raise the temperature of the adsorbent.
• the PSA method carries out adsorption under pressure, desorption under normal pressure, or adsorption under normal pressure and desorption under reduced pressure, and utilizes the fact that the adsorption capacity of an adsorbent has pressure dependency to perform adsorption and desorption. Is what you do.
• the PTSA method adsorbs at normal temperature and normal pressure and desorbs at high temperature and reduced pressure, and has features of the TSA method and the PSA method.
• the method of recovering the solvent in the desorbed gas in the fluidized bed type and the fixed bed type is as follows: cooling water, chilling unit at 0 to 5 ° C or a combination thereof is used to recover by cooling and condensing, and the unconcentrated gas is recovered. It was recirculated to the feed gas line.
• organic silicon-based compounds such as methoxytrimethylsilane are volatile, which complicates the coupling reaction equipment.
• organic silicon-based compounds are expensive, the coupling method is not suitable for industrial processes.
• high silica zeolite also has a problem in that the cost of dealuminating is high, and it is not economically acceptable to use it in an industrial process.
• an adsorbent that efficiently recovers VOCs is inexpensive and can withstand long-term use, in other words, has a large surface area, and is not affected by saturated steam.
• a non-combustible adsorbent that is difficult to receive.
• the recovery method in the conventional adsorption method since the adsorption Z desorption device eventually recovers the solvent through-through, for example, the recovery rate when the degassed gas is cooled and concentrated at 1 atm and recovered is reduced.
• Recovery rate (1-b / a) / (1-b) (where a is The partial pressure (a tm) of the hydrocarbon solvent in the landing gas is shown, and b shows the saturated vapor pressure (a tm) at the temperature difference when the target hydrocarbon solvent is cooled and concentrated. Therefore, it cannot be collected when a ⁇ b, and the collection rate becomes worse as the a value approaches the b value. Therefore, in order to increase the recovery rate, measures such as setting the b value lower or increasing the a value by providing a chilli guin as described above have been taken. Also, when the raw material gas concentration becomes lower, the concentration of the desorbed gas also decreases in proportion, which is not suitable for the fixed-bed adsorption method.
• an object of the present invention is to provide an economical adsorbent for V0C-PSA having both high V0C reversible adsorption ability and high hydrophobicity, and a method for producing the same. Further, an object of the present invention is to provide a method for recovering gaseous hydrocarbons contained in waste gas by an adsorption method, which does not require facilities such as chilling units and can be carried out with simple equipment. Another object of the present invention is to provide a method for easily and efficiently recovering. Disclosure of the invention
• an adsorbent composed of a porous molded body containing silica as a main component and having specific porous physical properties such as specific surface area, pore volume, and average pore diameter has excellent hydrophobicity and V 0. They have found that they have an adsorbing ability for C, and have completed the present invention. In addition, they have found that such adsorbents can be produced by heat treatment under specific conditions, and have completed the present invention.
• the adsorbent according to the present invention contains silica as a main component, has a specific surface area of 400 to 700 m 2 / g, and an average pore diameter of 0.4 to 3.0 nm. , And a water vapor adsorption amount of 3 to 10 m 1 -water vapor Z g —a selective adsorption of volatile organic compound gas having a carbon number of 1 to 12 consisting of a porous molded body of an adsorbent.
• "selectively adsorb volatile organic compound gas with 1 to 12 carbon atoms” means that volatile gas with 1 to 12 carbon atoms in gas and gas components except water vapor Organic compound Means that the substance gas is selectively adsorbed.
• the method for producing an adsorbent according to the present invention is a method for producing an adsorbent for selectively adsorbing a volatile organic compound gas having 1 to 12 carbon atoms,
• a specific surface area of 6 0 0 m 2 Zg above, forming a silica or silica gel scope and average pore diameter of the pore volume is 0. 0 5 ⁇ 0. 5 cm 3 Zg is 0.. 4 to 3. 0 nm
• the pellets are heated to a predetermined temperature in the range of 550 ° C to 700 ° C at a heating rate in the range of 1 to 20 ° C / min, and maintained at the predetermined temperature for a predetermined time.
• the adsorbent produced by the method of the present invention has a specific surface area reduction rate of 5 to 40% and a water vapor adsorption amount of 3 to 1 Oml Zg.
• heat treatment or sintering treatment is carried out while strictly controlling the temperature of the sili force or the sili force gel having certain physical properties to economically produce an adsorbent for V0C-PSA which is rich in hydrophobicity. It turned out that it can be produced in a special way.
• the heat treatment or the baking treatment physical properties that are important for the adsorptive capacity of the silica-silicone gel material are reduced.
• a specific organic compound is added to the silicic acid or the sily gel before the heat treatment. By doing so, it has been found that physical property deterioration can be suppressed.
• an inexpensive adsorbent having both high reversible adsorption capacity and high hydrophobicity can be realized using silica or silica gel, which is an inexpensive adsorbent raw material.
• the adsorbent according to the present invention comprises one or two selected from the group consisting of carboxylic acids and derivatives thereof, aldehydes and derivatives thereof, and thermally decomposable high-molecular organic compounds.
• the above organic compound was added to the raw material gel in an amount of 1 to 30% by weight based on the adsorbent, and then heat-treated at a temperature in the range of 400 to 75 ° C. be ⁇ 7 0 0 m 2 / g and an average pore diameter of 1. consists 7 ⁇ 5. 5 nm of the multi-porous molded silica dim, carbon atoms selectively adsorbs 1 2 of volatile organic compounds from 1 It is characterized by.
• the method for producing an adsorbent according to the present invention is a method for producing an adsorbent which contains silica as a main component and selectively adsorbs a volatile organic compound having 1 to 12 carbon atoms, comprising a carboxylic acid and a carboxylic acid.
• the raw material is one or more organic compounds selected from the group consisting of derivatives, aldehydes and their derivatives, and thermally decomposable high-molecular organic compounds
• a forming step of forming the siliceous gel having undergone the addition step to obtain a siliceous gel molded body is provided before the heat treatment step. Further, in the heat treatment step, the temperature of the silicic acid gel to which the compound is added is raised to a predetermined temperature at an average heating rate of 0.5 to 20 ° CZ.
• the present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, using an inexpensive and nonflammable silica gel as an adsorbent raw material, the silica gel has a specific content in silica gel.
• An adsorbent having a specific specific surface area and an average pore diameter, a high V 0 C adsorption ability and a high hydrophobizing ability can be invented by carrying a constant metal and heating.
• the adsorbent according to the present invention has an atomic ratio of the number of metal atoms to the number of silicon and metal atoms in silica gel of 200: 1 to 400: 0: 1. At least one metal selected from aluminum, zirconium and titanium in the silicon gel in a temperature range of 300 ° C., and then heat-treated at a temperature in the range of 300 ° C. to 700 ° C.
• a molded product having a specific surface area of 0 to 600 m 2 Zg and an average pore diameter of 1.0 to 4.0 nm, and a volatile organic compound having 1 to 12 carbon atoms. It is characterized by selective adsorption.
• the method for producing an adsorbent according to the present invention using a silica gel compact or a powdery silica gel as a raw material selectively absorbs a volatile organic compound having 1 to 12 carbon atoms.
• a silicon gel formed body or a powdery silicon gel having a specific surface area of 550 m 2 Zg or more and an average pore diameter of 1.0 to 4.0 nm, based on the number of silicon and metal atoms in the silicon gel
• the method has a step of forming a powdery gel having undergone the supporting step to form a powdery gel, before the heat treatment step.
• the silica gel compact When the metal is contained in the silica gel compact by the impregnation method, the silica gel compact is preliminarily heated at a temperature of 500 to 700 ° C before the loading step to prevent cracking of the silica gel. It has a pre-processing step for processing.
• the present inventors have found that in the method of recovering the gaseous hydrocarbons contained in the waste gas by the adsorption method, the desorbed gas is cooled at room temperature, If the unconcentrated gas containing hydrocarbons is returned to the inlet of the adsorber and the cycle is repeated, the concentration of gaseous hydrocarbons in the desorbed gas is gradually concentrated, and eventually the hydrocarbons in the desorbed gas are cooled at room temperature. Was found to be partially enriched, leading to the completion of the present invention.
• the present invention provides a method for recovering hydrocarbon vapor contained in waste gas or the like by an adsorption method
• the volatile organic compound of the present invention is composed of an adsorbent for adsorbing volatile organic compound gas (hereinafter simply referred to as an adsorbent): VOCs generated from medium and light fractions such as gasoline, naphtha, kerosene, and gas oil. It is suitable for adsorbing VOCs released from gasoline stands and oil tanks by the PSA method, since it can be used for the adsorption of water and has high hydrophobicity and high V 0 C adsorption ability.
• an adsorbent volatile organic compound gas
• V 0 C refers to a volatile organic compound gas having 1 to 12 carbon atoms
• V 0 C adsorption ability refers to the ability to adsorb VOC.
• volatile organic compounds are Hydrogen, halogenated hydrocarbon, and oxygen-containing organic compound.
• the specific surface area, pore volume, and average pore diameter indicating the porous physical properties of the adsorbent of the present invention are values measured by the BET method.
• the waste gas containing a gaseous hydrocarbon is not particularly limited, and can be used from a low concentration of several tens to several thousand ppm to a waste gas containing a high concentration of gaseous hydrocarbon of about 30%.
• the raw material of the adsorbent of the present invention has a specific surface area of at least 600 m 2 / g, preferably at least 600 m 2 Zg, and a pore volume of at least 600 m 2 / g as measured by a BET method using nitrogen molecules as a probe. It is silica or silica gel having a range of 5 to 0.5 cm 3 Zg, preferably 0.1 to 0.3 cm 3 Zg, and an average pore size of 0.4 to 3.0 nm.
• silica means a substance not containing water
• silica gel means a substance containing water
• the adsorbent raw material and the adsorbent may contain an inorganic component other than the sily force or the sily force gel.
• the practical upper limit of the specific surface area of the silicic acid gel material available on a scale at the industrialization level is currently about 800 m 2 Zg, but the adsorption capacity increases as the specific surface area increases. .
• the large specific surface area of the adsorbent means that the adsorption area of V 0 C molecules per unit weight or unit bulk volume of the adsorbent is large, and the adsorption capacity increases accordingly, so that high concentration V 0 C is adsorbed.
• an adsorbent having a large specific surface area may be used.
• VOC is adsorbed in addition to the large specific surface area.
• Optimum pore size for adsorbent It is important to give. This is because the V 0 C molecules are considered to be capillary condensed and adsorbed in the relatively small pores. Therefore, it is important that the adsorbent has a large surface area, a high probability of contact with V 0 C molecules, and a porous material with a small average pore diameter in order for the condensation process to proceed efficiently. become.
• the average pore diameter of the raw material silica gel or silica is preferably in the range of 0.4 to 3. Onm, and more preferably in the range of 0.6 to 1.5 nm.
• nitrogen molecules are usually used in many cases.
• the lower limit of the measurement of the pore volume and the pore distribution is a gap or a pore into which the nitrogen molecule can enter.
• the preferred pore volume of the raw material silica or silica gel is from 0.05 to 0.5 based on the correlation between the specific surface area, the pore volume, and the average pore size.
• cm 3 Zg more preferably 0.1 to 0.3 cm 3 / g.
• the pore diameter becomes too large, and it becomes difficult to smoothly promote the adsorption of V 0 C molecules. Conversely, if it is less than 0.05 cm 3 Zg, the pore diameter becomes too small, and it becomes difficult for VOC molecules to enter the pores.
• the material shape of the adsorbent raw material of the present invention various shapes such as a sphere, a column, and a tablet can be preferably used.
• Sili powder or sili gel powder can be used, but in this case, it is better to mold them into various shapes.
• the molding method a general molding method such as compression molding or extrusion molding can be preferably used.
• a binder may be appropriately added to facilitate molding.
• the size of the compact is determined by factors such as the size of the bed of the adsorbent and the allowable differential pressure.
• the diameter and length are preferably 2 mm to 10 mm, and more preferably 3 mn! ⁇ 8 mm is preferred. If it is less than this, the differential pressure becomes too large, and if it exceeds this, the gap between the compacts becomes too large.
• the adsorbent of the present invention can be obtained by subjecting the siliceous gel raw material or the siliceous raw material having the above physical properties to a predetermined hydrophobic treatment.
• the temperature is raised to the specified temperature in the specified range at the specified heating rate, and Hold for a predetermined time.
• the predetermined heat treatment temperature does not need to be constant during the predetermined time, and may vary within a specific temperature range.
• the heating rate may be 1 to 20 ° C / min, and more preferably 5 to 15 ° CZ. If the rate of temperature rise is higher than this, the difference in temperature between the surface and the inside of the raw material particles becomes too large, so that the raw material particles are likely to be cracked. Further, a heating rate higher than 20 ° CZ is not preferable because a predetermined temperature range may be exceeded (over-shouting) when shifting from heating to maintaining the temperature. Conversely, there is no theoretical problem if the heating rate is slow, but 1 is the practical lower limit because of economic reasons such as low productivity.
• the range of the heat treatment (firing) temperature is preferably from 550 ° C to 700 ° C, more preferably from 600 ° C to 700 ° C, and most preferably from 62 ° C to 70 ° C. 0 ° C.
• the firing time is not conditional as compared with the temperature condition, but is preferably 2 hours to 5 hours, more preferably 3 hours to 5 hours.
• the severity of the time range to be maintained is not high, but if it is less than 2 hours, the chemical reactions of formulas (1) and (2) may not proceed sufficiently. If it is longer than 5 hours, the productivity will be poor.
• the physical properties of the raw material of the adsorbent are important because of the need for chemical conversion.
• the pressure is swung at each adsorption step for a predetermined period of time.
• Quick adsorption is required, and the adsorption speed is one of the important factors. Therefore, in order to effectively adsorb V 0 C molecules, it is important to have a specific specific surface area, an average pore diameter and a hydrophobizing ability. As a result, the adsorption speed increases.
• the specific surface area reduction rate is preferably small.
• the specific surface area reduction rate exceeds 40%, the pore diameter changes due to thin ring, the VOC adsorption capacity decreases, and cracking due to volume change occurs. Inconveniences such as distortion occur.
• the reduction rate of the specific surface area shown in the formula (3) is kept at 40% or less, and the average pore diameter is close to that of the raw material of the gel. Becomes.
• an adsorbent having both excellent hydrophobizing ability and VOC adsorption ability and a high adsorption speed is realized.
• the adsorbent When the adsorbent is actually used in the PSA system, the adsorbent may be appropriately used depending on the operating conditions such as the volume and number of adsorption towers, VOC concentration in the inlet gas, VOC capture rate, and operating temperature. Decide the filling amount, filling height, etc.
• this adsorbent is used in combination with or mixed with a known adsorbent such as high silica zeolite or alumina.
• a known adsorbent such as high silica zeolite or alumina.
• the mixing amount or combination amount of known adsorbents is large, the economic advantage of the adsorbent of the present invention will be lost.
• the reduced pressure drying treatment may be appropriately performed at a temperature in the range of room temperature to 350 ° C. Although the drying time under reduced pressure is not determined unequivocally by the PSA apparatus, 1-2 hours is a realistic time.
• the V 0 C selectivity of the adsorbent referred to in the present invention is a ratio indicating the ratio of the amount of the volatile organic compound adsorbed to the amount of the water vapor and the volatile organic compound adsorbed by the adsorbent. It is a value defined by an expression.
• A is the equilibrium adsorption amount of the volatile organic compound to the adsorbent at a temperature of 20 ° C under a pressure of 110 of the saturated vapor pressure of the volatile organic compound at a temperature of 20 ° C (ml / g (stp)).
• B is the equilibrium adsorption amount of water vapor (m 1 / g (stp)) on the adsorbent at a pressure of 2 Hg and a temperature of 20 ° C.
• the amount of the volatile organic compound (VO C) in defining the equilibrium adsorption amount of the volatile organic compound (VO C) of the adsorbent, the amount of the volatile organic compound (VO C) must be not less than the saturated vapor pressure of VO C but 1/10 of the saturated vapor pressure of VO C. This is because most of the VOCs are adsorbed on the adsorbent before reaching the saturated vapor pressure of 1Z10. That is, actually, the adsorption amount under the saturated vapor pressure ⁇ the adsorption amount under the saturated vapor pressure of 1 to 10 times.
• the adsorption process usually does not pressurize to the saturated vapor pressure of VOC, and the pressure is within 110 V of the saturated vapor pressure of V ⁇ C. (The pressure may be lower than 1/10).
• the adsorption process is performed until the pressure reaches, and then the process moves to the desorption process.
• the VOC selectivity can be defined as a factor indicating the VOC adsorption efficiency during the operation of PSA.
• the VOC selectivity of the adsorbent is at least 80%, preferably at least 85%.
• Adsorbents with a V0C selectivity of 80% or more require less use of the adsorbent compared to adsorbents with a low V0C selectivity, and the PSA method has economical efficiency and operating efficiency. This is a great advantage in terms of.
• the amount of VOC adsorbed by the adsorbent is also an important factor.
• VOC selectivity even if the adsorbent has a high V 0 C selectivity, if the amount of adsorbed VOCs is small, there will be no problems such as the amount of adsorbent required to separate and recover a predetermined amount of VOC will be too large. You. Therefore, it is necessary to have a high VOC selectivity and exhibit a VOC adsorption amount equal to or higher than a predetermined level.
• the amount of VOCs adsorbed is the equilibrium adsorption amount of the volatile organic compound on the adsorbent at a temperature of 20 ° C under a pressure of 1 Z10, which is the saturated vapor pressure of the volatile organic compound at a temperature of 20 ° C (ml / g (stp)).
• the measuring method is the same as the method described in the measuring method of V 0 C selectivity.
• the equilibrium adsorption amount of the volatile organic compound to the adsorbent at a temperature of 20 ° C is 30 ml / g ( stp) or more, more preferably 35 ml / g (stp) or more.
• V 0 C adsorption amount is smaller than this, the amount of adsorbent required for the device to achieve the same effect increases, so the adsorption tower becomes larger and the standards of the equipment attached to the device also become As the size of the equipment increases, the operating cost is likely to increase due to an increase in the size of the entire device and an increase in power consumption.
• the upper limit is not particularly limited, but about 150 m 1 / g (stp) is considered to be the current upper limit.
• Siri force Si0 2
• amorphous silicon dioxide silica mosquito [Si 0 2]
• Particles primary particles
• a erogeDs This matrix contains water partially, has crystal water, and has A gel-like aggregate of solid colloid particles obtained by dehydration condensation of togaic acid (H 4 SiO 4 or the like) can be used.
• silica gel used as a raw material for the adsorbent in the present invention commercially available silica gel or silica can be used as it is, and soda gay acid (water glass) and mineral acid (sulfuric acid, hydrochloric acid, etc.) can be used.
• soda gay acid water glass
• mineral acid sulfuric acid, hydrochloric acid, etc.
• silica hydrosol which may be gelled.
• the gel may also be obtained by hydrolyzing or polycondensing an alkoxide such as ethyl geate (Si (0C 2 H 5 ) 4 ).
• Silica gel obtained by conversion into a gel may be used.
• a silica gel having a specific surface area of 500 m 2 Zg or more and an average pore diameter of 5 nm or less measured by the BET method using a nitrogen molecule as a probe is preferable, and the specific area is preferable.
• silica gel can be preferably used in various shapes other than a spherical shape, a cylindrical shape, a hollow shape, a tablet shape and the like, and there is no limitation on the shape.
• the particle size passing through a mesh of 50 to 200 mesh is preferable, and a powder of 100 to 200 mesh is preferably used so as not to hinder the molding step described later. The particle size passing through the sieve is more preferable.
• a binder or the like may be added.
• the component added to the silica gel is one or more selected from the group consisting of carboxylic acids and derivatives thereof, aldehydes and derivatives thereof, and thermally decomposable organic polymer compounds. Is two or more organic compounds, and the component added to the silica gel is hereinafter referred to as a second component.
• carboxylic acids examples include aliphatic monocarboxylic acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid; phenylacetic acid; Aromatic monocarboxylic acids such as lyulic acid and benzoic acid, alicyclic monocarboxylic acids such as cyclohexane carboxylic acid and cyclopentane carboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, oxalic acid Dicarboxylic acids such as malonic acid, malonic acid, succinic acid, daltaric acid, adipic acid, etc. You can do it.
• aliphatic monocarboxylic acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid
• phenylacetic acid Aromatic monocarboxylic acids such as lyulic acid and benzoic acid, alicyclic
• derivatization of carboxylic acids such as isomerization, alkylation, and phenylation that causes branching of an alkyl group does not prevent the physical properties of the carboxylic acids from being changed as necessary.
• aldehydes acetate aldehyde, propion aldehyde, butyl aldehyde, barrel aldehyde, urea aldehyde, heptaaldehyde, tolu aldehyde, benz aldehyde, glioxizal and the like can be preferably used.
• the thermally decomposable high molecular weight organic compound is a high molecular weight organic compound that decomposes at a temperature in the range of 400 to 750, for example, polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), Polyvinyl acetate (p-PVAc), polyvinyl pyrrolidone (PVP), melamine formaldehyde resin, polyamide formaldehyde resin, cyclodextrin (CD), cellulose acetate, methylcellulose, carboxy Methyl cellulose (CMC) can be used preferably.
• PVA polyvinyl alcohol
• PVAc polyvinyl acetate
• p-PVAc Polyvinyl acetate
• PVP polyvinyl pyrrolidone
• CD cyclodextrin
• CD cyclodextrin
• the molecular weight (degree of polymerization) of the thermally decomposable high molecular weight organic compound may be appropriately selected in consideration of the availability, price, properties, and the like.
• the sily gel powder and the second component powder may be sufficiently kneaded using a mixer such as an automatic mortar.
• a solvent or a dispersion medium is added and kneaded, and the mixture is dried before the molding step.
• the second component is liquid, the addition of the solvent and the dispersion medium may be omitted.
• the addition of the second component by the impregnation method can be applied to both the gel and the powder.
• an example using water as the solvent of the second component will be described. The same applies when using a solvent other than water.
• the silica gel When the silica gel is dried, in the case of silica gel powder, it may be dried by heating at 80 to 200 ° C. for 1 to 3 hours. In the case of a silica gel molded body, if it is immersed in a solvent to be used in the impregnation step described below and cracks do not occur within the impregnation time, it is only necessary to perform a drying treatment similarly to the silica gel powder. On the other hand, if cracks occur within the impregnation time, pre-heating is performed to prevent cracks.
• the heating temperature and the heating time vary depending on the physical properties of the silica gel and the type of the solvent used, and are not unconditionally determined, but are usually from 300 to 400. Perform with C for 30-60 minutes. In addition, when the molded product is hard to be broken or when a solvent that is hard to be broken is selected, the preheating can be omitted.
• the saturated water absorption is determined by measuring the weight of the gel with sufficient water absorption by dropping water from a pipette bottle, and then subtracting the weight of the gel itself.
• the silica gel When impregnating the second component, the silica gel is sufficiently dried in the same manner as when the saturated water absorption is determined. That is, when silica gel powder is used, drying When using a resilient gel, perform a drying treatment and, if necessary, a heating treatment for a predetermined time.
• Drying conditions vary depending on the production amount of the adsorbent and the type of solvent, but it is practical to complete the drying in less than the decomposition temperature of the second component in about 1 to 24 hours.
• a solvent in which the second component is easily dissolved can be selected.
• a solvent having sufficient solubility of the second component and easily removable can be appropriately selected from alcohols, ketones, saturated hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, unsaturated hydrocarbons, and the like. good.
• the amount of the second component is preferably from 1 to 30% by weight, more preferably from 5 to 25% by weight, and most preferably from 5 to 20% by weight based on the adsorbent.
• the hydrophobizing effect and the effect of maintaining the physical properties of the raw material silica gel are both poor. If it exceeds 30% by weight, undecomposed components remain in the heat treatment stage or are adsorbed conversely. The physical properties of the agent may be impaired.
• powdered silica gel When powdered silica gel is used, it is molded after adding the second component.
• a molding method a known method such as compression molding, extrusion molding, or granulation can be preferably used.
• the shape may be selected according to the adsorption process, such as columnar, spherical, or hollow.
• the size is not particularly limited, but about 1.5 mm to 10 mm is considered to be a practical size.
• the silicic acid gel to which the second component has been added is heated in the air to raise the temperature to a predetermined temperature range, and then maintained at that temperature range.
• the temperature of the heat treatment is preferably from 400 to 750 ° C, more preferably from 450 to 680 ° C, and most preferably from 500 to 680 ° C. Heating below 400 ° C is insufficient for the hydrophobic effect and conversely, 75 If the temperature exceeds 0 ° C, the material is hydrophobized, but physical properties such as surface area shrinkage are remarkably reduced, and the amount of reversible adsorption of V 0 C is undesirably reduced.
• the average heating rate when the temperature is raised to the temperature range of the heat treatment is preferably 0.5 ° CZ min to 20 ° C / min, more preferably 1.5 ° CZ min to 15 ° CZ min. Minutes at 3 to 10 minutes are the most preferred. If it is less than 0.5 ° CZ, it takes too much time and productivity is low, so it is not economical. Conversely, if the temperature is raised faster than 20 ° CZ, the silica gel molded article may crack. Also, at the actual production scale, 20 ° C / min is a fairly fast category and can be considered the upper limit.
• the heating rate may be changed on the way or may be maintained at a certain temperature for a while.
• the rate of temperature rise from 550 to 570 to a higher temperature should be 0.5 to 7 ° CZ minutes or less, preferably 0.
• the temperature By setting the temperature to 5 to 5 ° CZ, and more preferably to 0.5 to 3 ° CZ, cracks can be almost completely prevented.
• the holding time of the molded article at that temperature is preferably 2 to 5 hours, more preferably 3 to 4 hours, depending on the treatment amount. If the retention time is shorter than 2 hours, the strength of the adsorbent may be insufficient, undecomposed additives may remain, or the hydrophobicity may be insufficient. Conversely, even if the holding time is longer than 5 hours, further performance improvement by extending the time cannot be expected, and thus not only has no technical significance, but also lowers productivity.
• the specific surface area of the V 0 C—PSA adsorbent obtained by adding the second component and performing the heat treatment is preferably 450 to 700 m 2 Zg, and 500 to 7 0 0 m 2 Zg is laid more preferred, most preferred lay is 5 5 0 ⁇ 7 0 0 m 2 Zg, average pore diameter 1.7 ⁇ 5. lay preferred is 5 nm, 2. 0 ⁇ 4. 5 nm Is more preferable.
• the pore volume is preferably from 0.2 to 0.7 ml Zg.
• the specific surface area is less than 450 m 2 Zg, the reversible adsorption amount of V 0 C is small. As a result, the amount of adsorbent to be used increases in practical use, and the cost increases. Conversely, although the upper limit of the specific surface area is preferably higher, the available silica gel has a specific surface area of about 800 m 2 Zg, so that 70 O m 2 Zg can be regarded as a practical upper limit.
• the average pore diameter When the average pore diameter is less than 1.7 nm, it becomes difficult to adsorb VOC molecules having a large molecular size and therefore a large molecular weight. Conversely, when the average pore diameter exceeds 5.5 nm, the amount of reversible adsorption tends to decrease, for example, because capillary action is less likely to occur.
• the pore volume When the pore volume is less than 0.2 m 1 / g, the reversible adsorption amount tends to be too small. Generally, as the pore volume increases, the specific surface area tends to decrease.Conversely, when the pore volume exceeds 0.7 ml / g, it becomes difficult to secure the required specific surface area. . In addition, there is a disadvantage that as the pore volume becomes larger, the capillary phenomenon is less likely to occur.
• the second component is decomposed during the heat treatment, and reactive reactive species such as methyl radicals (alkyl radicals) are generated. It can be inferred that the mechanism is such that it is formed and undergoes some reaction with hydrophilic groups (SiOH) such as silanol groups on the surface of the silica gel to produce hydrophobic methyl groups (alkyl groups) on the surface.
• SiOH hydrophilic groups
• the functional groups of carboxylic acids, aldehydes, and thermally decomposable polymers interact with the hydrophilic groups (SiOH groups) on the silica gel surface to generate decomposable species near the hydrophilic groups. It can also be assumed that the surface is rendered hydrophobic.
• hydrophilic groups on the silica gel surface are dehydrated and condensed by heating to form a kind of ether bond, which is considered to exert a hydrophobic effect in combination.
• the reaction between the second component and the hydrophilic group on the surface of the silica gel produces a hydrophobic effect. It is thought that the hydrophobic effect is exhibited by both the hydrophobization by the reaction between the two components and the hydrophilic group and the condensation of the hydrophilic group by heat.
• the silica gel used as a raw material of the adsorbent of the present invention may be in any form of a silica gel compact or a powdered silica gel, and may be a constituent material.
• Te may be any dry gel consisting of colloids particles Siri mosquito (Si0 2), the particles of amorphous silicon dioxide for example (two silica mosquito [Si0 2]) (primary particles) are countless bonded, porous air outlet gel forming quality structure (Airgel), those containing some water in the Conclusions Li Tsu box, dewatering of those with crystal water, and ol Bok Gay acid (H 4 Si0 4, etc.) A gel-like aggregate of solid colloid particles by condensation can be used.
• silica gel used as a raw material for the adsorbent in the present invention a commercially available silica gel or silica can be used as it is, or a mixture of sodium gayate (water glass) and a mineral acid (sulfuric acid, hydrochloric acid, etc.).
• a silica hydrosol may be prepared by gelation, and the gel may be obtained by gelation.Also, an alkoxide such as ethyl ethylate (Si (0C 2 H 5 ) 4 ) may be hydrolyzed and polycondensed to form a gel. It may be a silica gel obtained by the above method.
• the raw material gel has a specific surface area, a pore volume, and an average pore diameter measured by the BET method using nitrogen molecules as a probe within the following ranges.
• the difference between the average pore diameter of the raw material silica gel and the average pore diameter of the product adsorbent is extremely small, and the diameter of the average pore diameter hardly occurs during the adsorbent production process.
• the average pore size of the raw material gel can be determined through consideration of the average pore size of the product adsorbent.
• the average pore diameter of the starting silica gel is preferably not more than 4. Onm. Considering the size of the VOC molecule, the practical lower limit of the average pore diameter of the raw material silica gel is 0.3 nm. Also, as the average pore diameter of the product adsorbent is smaller, capillary condensation of VOC is more likely to occur, which is preferable. On the other hand, the VOC diffusion rate in the pores decreases, and the VOC adsorption rate decreases. Conversely, the porosity increases as the average pore size increases, and the mechanical strength of the product adsorbent decreases. Considering the mechanical strength of the product adsorbent, the VOC adsorption rate, etc., the average pore size of the starting silica gel is preferably 1.0 to 4.0 nm, more preferably 1.2 to 2.5 nm.
• the pore volume of the raw material silica gel does not need to be particularly limited if the specific surface area and the average pore diameter are defined, since the value of the pore volume is naturally determined.
• the preferred pore volume is in the range of 0.20 to 0.70 mlZg. Further, considering the mechanical strength of the adsorbent, the V 0 C adsorption capacity, and the like, 0.3 to 0.65 m 1 is more preferable, and particularly 0.3 to 0.45 m 1 is most preferable. New
• the metal is carried in a form in which the metal atom or the metal in the metal salt or the metal compound carried on the silica gel during the production process is converted into another metal compound.
• the metal in the present invention refers to a metal element itself such as aluminum [Al], zirconium and r]> titanium [Ti], and the metal salt includes, for example, aluminum nitrate nonahydrate, zirconium oxynitrate dihydrate.
• Metal compounds such as hydrates and titanium sulfate Refers to an object.
• metal salts of aluminum, zirconium and titanium nitrates, oxynitrates, carbonates, sulfates, acetates, lactates and the like can be preferably used, and metal nitrates are more preferably used. I can do it.
• metal salts both anhydrides and hydrates can be preferably used, it is sufficient to use easily available substances.
• chloride has no cost advantage compared to other metal salts, and conversely, chlorine root may remain in the adsorbent, and will be described below. It is not preferable because chlorine and the like are generated at the stage of the heat treatment.
• the adsorbent of the present invention includes organic liquid compounds such as organic solvents for coating and chlorinated organic solvents for cleaning, fuels for transportation such as gasoline, kerosene and light oil, and organic liquids used for printing. It is suitable as an adsorbent for collecting VOCs generated from compounds and the like.
• V 0 C refers to a volatile organic compound gas having 1 to 12 carbon atoms
• VOC adsorption ability refers to the ability to adsorb VOC.
• the adsorbent of the present invention can be preferably used as an adsorbent when performing a known adsorption method such as the PSA method, the TSA method, and the PTSA method.
• the method for producing an adsorbent according to the present invention basically includes a metal supporting step (metal salt adding step) and a heat treatment step.
• the method has a pretreatment step of preliminarily heating the silica gel compact or the powdery silica gel at a temperature of 500 to 700 ° C.
• the heat treatment before the metal loading step is to remove the water in the raw silica gel temporarily and to make the metal aqueous solution sufficiently reach the pores of the raw silica gel in the metal salt addition step, and This is done for reasons such as baking the raw material silica gel and preventing the raw material silica gel from cracking when impregnating in the metal salt addition step.
• the metal salt easily reacts with the surface of the starting silica gel, and the remaining surface silanol groups of the starting silica gel decrease.
• the effect of reducing the amount of water adsorbed and inhibiting the adsorbed water from adsorbing V 0 C It becomes smaller, and V 0 C adsorption can be performed by effectively using the adsorbent surface.
• the higher the heating temperature the lower the surface area due to sintering.
• the heating temperature is preferably in the range of 500 to 700, and the heating temperature is preferably in the range of 500 to 700, so as to maintain an appropriate surface area and appropriately remove surface silanol groups.
• the range of 0 ° C is more preferable, and particularly preferably 550 to 65 ° C.
• the heating time varies depending on the heating temperature, but it is sufficient if the heating time is 1 to 24 hours.
• the rate of temperature rise to the heating temperature may be such that sintering due to a rapid temperature rise does not occur, and 0.1 to 3.0 ° C.Z is preferable.
• the heat treatment does not necessarily need to be performed in an inert gas atmosphere, but may be performed in air.
• the pre-treatment applied to the silica gel is performed as necessary for the purpose of imparting water resistance and mechanical strength, and is necessary for powdery silica gel to which a metal salt is added by kneading. Not necessary.
• the method of adding the metal there is no limitation on the method of adding the metal as long as the metal can be supported on the silica gel.However, the impregnation method is practical for silica gel compacts, and dry kneading and wet kneading for powdered silica gel are practical. A kneading method and an impregnation method can be applied.
• the sily gel and a predetermined amount of metal salt are sufficiently kneaded in an automatic mortar or the like.
• a metal salt and a dispersing medium such as water and a liquid organic compound are added to a silica gel to form a slurry, which is thoroughly kneaded in an automatic mortar, and then dried. I do. Prior to the addition, it is preferable that the silica gel and the metal salt are sufficiently crushed using an automatic mortar or the like.
• a method of adding a metal by the impregnation method will be described below.
• the saturated water absorption of silica gel is determined.
• the saturated water absorption varies greatly depending on the physical properties of the silica gel, it is desirable to perform the water absorption test several times to obtain the average value.
• the volume may be obtained using a measuring instrument such as a burette, or the weight may be obtained using a balance or the like.
• a solvent other than water for example, an organic solvent such as alcohol or ketone such as methanol or ethanol, the same operation as water is performed to obtain a solvent adsorption amount having the same significance as the saturated water absorption. Can be obtained.
• a predetermined amount of sily gel is weighed, an amount of water equal to the saturated water absorption of the sily gel is measured, and a predetermined amount of the added metal salt is dissolved in the water to prepare an impregnation liquid.
• a predetermined amount of the silica gel previously measured is immersed in the prepared aqueous metal salt solution, and left for a sufficient time to be impregnated.
• the impregnation time shall be longer than the water absorption time required for obtaining the saturated water absorption.
• the drying temperature is lower than the decomposition temperature of the metal salt at normal pressure or under atmospheric pressure. Usually, it is carried out at about 10 ° C. under normal pressure and in the atmosphere.
• the drying time varies depending on the amount of silica gel, but is about 1 to 24 hours.
• the amount of metal salt added depends on the specific reactivity of the metal, the heating temperature, etc. Requires the amount of metal that reacts with However, if there is too much metal salt, excess will be deposited on the silica, impairing the adsorbent performance.
• the amount of metal to be added is such that the atomic ratio of the number of metal atoms to the number of silicon and metal atoms in the silica gel is in the range of 200: 1 to 400: 1, preferably 400: 1. 1 to 3200: Add in the range of 1.
• the metal is at least one of aluminum, zirconium and titanium.
• the atomic ratio refers to the number of metal atoms to the number of metal atoms (aluminum [Al], zirconia [Zr], titanium [T i]) and silicon [S i] atoms in silica gel.
• the atomic ratio can be calculated from the charged amounts of the raw silica gel and the raw metal salt. It is calculated by the following equation.
• Atomic ratio S i: M
• 6 2 silica dim 1 0 0 g of aluminum nitrate nonahydrate [ ⁇ 0 3) 3 ⁇ 9 ⁇ 2 0] 0.
• Atomic ratio 1.65 3 X 10 " 3 : (1.653 x 10 + 1.664)
• a silica gel to which a metal salt is added is formed.
• the purpose of molding is to impart mechanical strength to the adsorbent and to reduce pressure loss when the adsorbent is filled in the adsorption tower.
• a well-known molding method such as tableting (pelletizing) or extruding (extruding) is used to obtain a resin having an appropriate size, for example, a length and a diameter of about 2 mm to 10 mm in a normal PSA adsorbent. is there.
• the buffer should be used as long as it does not interfere with the performance of the adsorbent. You may add a binder.
• the heating temperature may be any temperature at which the metal salt is decomposed and sufficient interaction with the silanol groups on the surface of the silica gel can be performed, and is preferably from 300 to 700 ° C.
• the temperature range of the heat treatment depends on the easiness of decomposition of the metal salt, and therefore, the kind of the metal salt, the method of addition and the physical properties of the raw material silica gel. However, at a temperature of 300 ° C or lower, the decomposition of the metal salt is not completely completed, and a part or all of the added metal salt remains in the form as it is.
• the temperature of the heat treatment is at least 300 ° C.
• the contact area between the raw material silica gel and the metal salt is smaller than that by the impregnation method, so that the temperature of the heat treatment is relatively high, for example, 500 -700 ° C is preferable, 500 to 680 ° C is more preferable, and 550 to 650 ° C is particularly preferable.
• the contact area between the raw material gel and the metal salt is larger than in the case of the kneading method, so that even if the heat treatment temperature is relatively low, it is sufficient.
• the metal salt interacts with the silica gel surface, for example, it is preferably from 300 to 550 ° C, more preferably from 300 to 500 ° C, and from 300 to 400 ° C.
• C Power Most preferred. Heating at a high temperature of 5 5 (TC or more reduces the surface area of the adsorbent, lowers VOC adsorption performance, and causes inconveniences such as cracking and distortion due to volume change.
• the rate of temperature rise to the heat treatment temperature may be such that sintering due to a rapid temperature rise does not occur, preferably 0.1 to 20 ° C, and more preferably 0.1 to 10 ° CZ. It is preferably 0.1 to 3.0 ° CZ. A heat treatment time of about 3 to 24 hours is sufficient.
• the heat treatment can be preferably performed at normal pressure or reduced pressure in air, in an inert gas atmosphere such as nitrogen or helium, or in a reducing gas atmosphere such as hydrogen or carbon monoxide.
• the heat treatment causes the metal salt and silica gel to interact,
• the metal salt is decomposed by heat treatment and interacts with the surface silanol groups of the silica gel to reduce the surface silanol groups, thus making the adsorbent hydrophobic. Ability develops.
• metal salt decomposition described above is very difficult to verify by instrumental analysis because the amount of metal salt added is very small, but in any case, the metal salt is decomposed by heat treatment. However, it interacts with the silanol groups on the surface of the silica gel and reduces the silanol groups on the surface.
• the adsorption method may be either a fluidized bed type or a fixed bed type, but a fixed bed type is preferred.
• adsorption and regeneration methods any of the TSA method, the PSA method and the PTSA method can be used, but the PSA method or the PTSA method is preferred.
• the tower type of the adsorption method is not particularly limited, and examples thereof include a two-column type having one column for adsorption and desorption, or a three-column type having one column for adsorption and two columns for desorption. Of these, the three-column system is preferred because the amount of purge gas used in the desorption step described later can be reduced.
• an adsorption device that alternately performs adsorption and desorption is used, and a waste gas containing gaseous hydrocarbon is passed through one of the adsorption devices, and the gaseous hydrocarbon is used as the adsorbent.
• the method includes switching to a desorption device, sucking a gaseous hydrocarbon adsorbed on an adsorbent with a vacuum pump to desorb the gaseous hydrocarbon from the adsorbent layer, and recovering the gaseous hydrocarbon from the desorbed purge exhaust gas.
• the adsorbent used here is not particularly limited, and includes, for example, activated carbon, zeolite and hydrophobized silica gel.
• hydrophobized silica gel is nonflammable, inexpensive and easily available. It is preferable because it is.
• the present invention relates to a method for recovering gaseous hydrocarbons contained in waste gas by an adsorption method as described above, wherein: (A) cooling the desorbed gas at room temperature to remove the non-enriched gas containing gaseous hydrocarbons into the adsorber; After returning to the inlet, the gaseous hydrocarbon concentration is increased by mixing with the gas to be treated and sent to the adsorption device. After the adsorption step, (B) Next, the concentration of gaseous hydrocarbons in the desorbed gas is measured for the gas to be treated alone. This is a method in which the concentration is made higher than that in the case of treating with, and the above (A) and (B) are repeated to condense and recover a part of the hydrocarbons in the desorbed gas by cooling at room temperature.
• gaseous hydrocarbons adsorbed on the adsorbent layer are sucked by a vacuum pump, evacuated under reduced pressure, and desorbed from the adsorbent layer.
• the vacuum pump include a liquid ring vacuum pump and a completely dry vacuum pump.
• a completely dry vacuum pump is preferable.
• the degree of decompression is not particularly limited, but is preferably in the range of 25 to 100 Hg.
• part of the treated clean gas or air discharged from the adsorption tower in the adsorption step as a purge gas is introduced into the tower in the desorption step.
• the purge gas amount is not particularly limited, it is preferable that the actual flow rate is set to be equal to or less than 130% of the gas to be treated.
• the smaller the amount of the purge gas the higher the concentration of hydrocarbons in the desorbed gas, the easier the concentration during cooling, and the smaller the capacity and power of the vacuum pump, but the worse the regeneration of the adsorbent.
• the relationship between the purge gas and the exhaust gas can be expressed by the following equation.
• the purge gas in the desorption step is supplied to the second column, third column, and true column. It is preferable to flow in series in the order of empty pumps.
• the desorption time is equal to the adsorption time, and within this time the amount of purge gas required for desorption is supplied. In this case, the desorption time can be twice as long as the adsorption time. Therefore, the purge gas amount can be about 50 to 60% of the two-column system.
• the suction amount is the same as in the two-column method.
• the purge gas is flowed in series, the purge gas discharged from the tower that has entered the desorption step first (the second tower) has a low hydrocarbon content, and therefore the tower that has entered the desorption step later (3rd tower above).
• the first column (the second column) in the desorption step enters the adsorption step
• the second column (the third column) enters the first column in the desorption step
• the first column in the adsorption step enters the adsorption step.
• the tower will be the second tower in the desorption process.
• the desorbed gas is cooled at room temperature.
• the room temperature is not particularly limited, but is in a temperature range of about 10 to 30 ° C, preferably about 20 ° C, and the cooling means is not particularly limited. It is preferable to use a cooler with cooling water.
• the desorbed gas is a lean gas and does not liquefy at room temperature cooling. Therefore, all the gas is returned to the inlet of the adsorption device as unconcentrated gas and mixed with the gas to be treated. As a result, a gas having a concentration higher than the initial gaseous hydrocarbon concentration is fed into the adsorption device.
• the desorption gas step is performed again.
• the concentration of gaseous hydrocarbons in the desorbed gas is higher than when the gas to be treated is treated alone.
• the gaseous hydrocarbon concentration in the desorbed gas becomes higher one after another, and finally, a part of the hydrocarbons in the desorbed gas is concentrated by cooling at room temperature.
• the partial pressure of the gaseous hydrocarbons in the purged exhaust gas should be higher than the saturated vapor pressure of the hydrocarbons.
• Hydrocarbons at or above the saturated vapor pressure are condensed, and gas containing unconcentrated hydrocarbons corresponding to the saturated vapor pressure returns to the inlet of the adsorption device and is mixed with the gas to be treated.
• the saturated vapor pressure of toluene is 20 ° C, it is 22 mmHg (2.9 vol%), so concentration starts when the partial pressure of hydrocarbons in the purged exhaust gas exceeds 22 mniHg. 2.9 vo concentration of gas returns to the inlet of the adsorber.
• FIG. 1 is a flowchart illustrating a method for recovering gaseous hydrocarbons contained in waste gas according to an embodiment of the present invention.
• porous physical properties, hydrophobizing ability, and V 0 C adsorption ability of the sample adsorbents of the following Examples and Comparative Examples were evaluated by the following measurement methods and evaluation methods.
• porous physical properties of the adsorbent raw material (hereinafter referred to as “raw material properties”) and the porous physical properties of the adsorbent obtained by the hydrophobization treatment (hereinafter referred to as “adsorbent physical properties”) were determined by using high purity N2 (Takachiho Chemical, Research Grade) as a probe molecule ( It was measured using an automatic surface area and pore size measuring device (Belsorp28, manufactured by Bell Japan Co., Ltd.).
• an automatic dewar with an automatic liquefied nitrogen feeder was used, the temperature was maintained at the liquefied nitrogen temperature (1196 ° C), and the dead volume (dead vol. ume) was measured three times or more with high-purity helium, and after evacuation, the specific surface area was measured by introducing a probe molecule (nitrogen) according to the BET method. Next, a desorption measurement was carried out, whereby an average pore diameter was determined.
• the equilibrium adsorption amount of water vapor was measured at a temperature of 20 T; and a pressure of 2 mmHg.
• the sample adsorbent was subjected to the following reduced pressure heating treatment as a pretreatment. That is, putting a sample of about 1 0 0 mg in a glass sample tube up to 3 5 0 from room at a heating rate 6 ° CZ min while the pressure was reduced to pressure of 1 0- 1 ⁇ 1 0- 2 mmHg The temperature was raised and maintained at the same temperature for 1 hour. Next, the sample was cooled to room temperature at a rate of 5 ° C / min to obtain a sample adsorbent. The weight of the obtained sample adsorbent was accurately measured and used as a sample for measurement.
• the water used as the water vapor source was 50 ml of ion-exchanged water placed in a glass liquid reservoir, which was bubbled with a reduced pressure line, and then carefully cooled at the bottom of the liquid reservoir with dry ice and methanol refrigerant. while frozen Te was dissolved gas is released without leaving rows evacuation in about 1 0- 2 mmHg. Subsequently, it was heated and thawed. This process was repeated until no dissolved gas was released to obtain purified water.
• a high-precision vapor adsorption amount measurement device (Belsorpl8, manufactured by Per Japan) was used.
• a glass reservoir that maintains the saturated water vapor generated from the liquid reservoir at 50 ° C ⁇ 1 ° C while maintaining the liquid reservoir of the purified water at 50 ° C ⁇ 1 ° C in the air oven.
• volume of 150 ml volume of 150 ml
• only the part containing the sample adsorbent is kept at 20 ° C ⁇ 0.5 ° C in the glass adsorption tube from the reservoir to the automatic flow control valve. Water vapor was gradually introduced through the, and continued until an equilibrium pressure of 2 mmHg was reached.
• the equilibrium pressure of 2 mmHg that is, when the pressure fluctuation within 10 minutes is within 0.1 mmHg
• the amount of water introduced is calculated from the pressure measured with the capacitance manometer and the internal volume of the system. Then, the equilibrium adsorption amount per adsorbent weight was calculated based on the sample weight after pretreatment. An adsorbent with a smaller equilibrium adsorption amount can be evaluated as having a higher hydrophobicity.
• the reversible adsorption amount of VOC was measured as follows. That, i - C partial pressure 3 0 0 Hg of 5, the partial pressure of water vapor 1 0 mraHg, total pressure 7 6 0 mmHg of Isopen evening the Hmm steam one air gas mixture of 2 0 ° to the balance dry air
• the sample was adsorbed on the sample adsorbent with C, and the amount of irreversible adsorption of isopentane after 5 minutes was measured, and the result was regarded as the amount of VOC reversible adsorption.
• the sample adsorbent Prior to the measurement, the sample adsorbent was subjected to the following reduced pressure heat treatment as a pretreatment. Vacuum in the heating treatment, first, a sample of approximately 1 0 0 mg placed in the sample tube, 1 0- 1 ⁇ 1 0- 2 ininHg 3 5 0 from room at a heating rate 6 ° CZ min while the pressure was reduced to a pressure of And kept at this temperature for 1 hour. Next, the sample was cooled to room temperature at a temperature lowering rate of 5 ° CZ to obtain a sample adsorbent. In the measurement of the VOC adsorption capacity, a required sample weight was accurately weighed from the obtained sample adsorbent and used for the measurement.
• isopentane to be used for the measurement was purified as follows. First, isopentane (Tokyo Kasei Kogyo Co., Ltd., reagent grade) is placed in a liquid reservoir and bubbled in a vacuum line. Then, the liquid surface of the liquefied nitrogen in a bottle is carefully brought into contact with the bottom of the liquid reservoir and cooled to solidify. while, was evacuated at 1 0 one 2 thigh Hg board while releasing the dissolved gas. Then it was heated and melted. This operation was repeated until no dissolved gas was released, to purify isopentane.
• isopentane Tokyo Kasei Kogyo Co., Ltd., reagent grade
• Water used as a water vapor source was purified in the same manner as in the evaluation of the hydrophobicity.
• saturated steam generated from the liquid reservoir was introduced into a glass reservoir (reservoir, volume: 150 ml) maintained at a temperature of 50 ° C ⁇ 1 ° C to a pressure of 30 mmHg, Furthermore, water vapor was gradually introduced from a reservoir through an automatic flow control valve into a glass adsorption tube in which only the portion containing the sample adsorbent was kept at a temperature of 20 ° C ⁇ 0.5 ° C. , Ten The introduction was continued until an equilibrium pressure of mmHg was reached. Next, from the pressure measured by the capacitance manometer and the internal volume of the system, the amount of water absorbed when the equilibrium pressure of 10 mmHg was reached was determined.
• the isoprene vapor generated from the liquid reservoir was introduced into a glass reservoir (volume: 150 m1) maintained at a temperature of 50 ° C ⁇ 1 ° C to a pressure of 540 mmHg,
• the isoprene vapor was gradually fed from the reservoir through an automatic flow control valve to a glass adsorption tube in which only the portion containing the sample adsorbent was kept at a temperature of 20 ° C ⁇ 0.5 ° C.
• the introduction was continued until the equilibrium pressure reached 540 mmHg.
• the equilibrium adsorption amount was the adsorption amount when the pressure fluctuation within 10 minutes became within 0.1 mmHg.
• the amount of adsorbed isopentane was determined from the change in pressure measured by a capacitance manometer and the volume in the system, and the amount of adsorbed per adsorbent was calculated based on the sample weight after pretreatment.
• water vapor was introduced from a liquid reservoir into a glass reservoir (150 m1) at 1 OmmHg, and subsequently, an isopentane vapor was introduced from the liquid reservoir into a glass reservoir.
• 300 mmHg was introduced into the mixture to prepare a mixed gas of water and isopentane at a total pressure of 310 mmHg.
• dry air was introduced into a glass reservoir, and the total pressure was adjusted to 825 mmHg.
• the pressure was measured with a capacitance manometer, and the residual isopentane after the adsorption was measured by an absolute calibration method using a gas chromatograph equipped with a hydrogen flame ionization detector (FID-GC).
• FID-GC hydrogen flame ionization detector
• a gas mixture of isopentane / water / air was gradually introduced into the glass adsorption tube maintained at 20 ° C ( ⁇ 0.5 ° C) only through the automatic flow control valve, and the sample section containing the sample adsorbent was gradually equilibrated.
• the amount of adsorbed isopene was measured at a pressure of 76 O mmHg and an equilibrium pressure of 2 OmmHg.
• the pressure swing of 76 OmmHg and 2 OmmHg was repeated three times, and the reversible adsorption amount of isopentane (standard state conversion (stp)) was obtained from the difference between them, and the measured value was averaged. It can be evaluated that the higher the reversible adsorption amount of isopentane, the higher the VOC adsorption capacity.
• Measurement of water vapor adsorption and VOC adsorption is performed using a high-precision vapor measurement device (Belsorpl8, manufactured by Bell Japan). Opening / closing and adjustment of flow control valves are performed using a PC (PC982K manufactured by NEC). It was controlled online.
• This method of calculating the reversible adsorption amount of isopen resin was performed assuming the operation of the PSA process, and the relative evaluation of the adsorbent performance in the actual process can be performed by calculating the reversible adsorption amount of VOC. it is conceivable that. Isopentane is selected as a representative gas of VOC and has a different absolute adsorption amount than the case where other VOCs are used, but there is no problem in the relative evaluation between adsorbents.
• the adsorbent according to the present invention is an adsorbent capable of selectively and efficiently adsorbing VOC with a low concentration of V0C in the atmosphere around gasoline stands, oil tanks, etc., that is, V0C mixed with air to some extent. is there.
• a problem in the adsorption and recovery of such low-concentration V 0 C is the effect of moisture contained in air, and the adsorption of moisture causes a decrease in VOC adsorption ability.
• an excellent adsorbent for low concentration V 0 C is an adsorbent that is not easily affected by moisture.
• the adsorbent When moisture and V 0 C coexist, the adsorbent usually preferentially adsorbs water, so the adsorbent's V 0 C adsorption capacity is reduced.
• water is first adsorbed on the adsorbent, then VOC is adsorbed, and the adsorbing ability is evaluated. This means that the V0C adsorption capacity is evaluated in a state where the water content is high, that is, the state where the V0C concentration is low.
• the adsorbent is in a low-concentration V 0 C atmosphere or under more severe conditions,
• the ability to adsorb large amounts of VOC even after adsorption correlates with high accuracy in the ability to adsorb low concentrations of VOCs.
• the equilibrium adsorption amount of water vapor (m 1 (s tp)) to the adsorbent at a pressure of 2 mmHg and a temperature of 20 ° C is measured by the equilibrium adsorption amount of water vapor described in the evaluation method of adsorbent's hydrophobicity.
• the method is performed according to
• the organic compound used for the measurement is purified in advance. For example, taking isopentane as an example, first place a special grade of reagent, isopentane, in a reservoir, bubbling in a decompression line, and then carefully contact the liquefied nitrogen surface in a Dewar bottle with the bottom of the reservoir. Iso Penta down cooled while solidifying, 1 0 - 2 in vacuum mmH g the order to release dissolved gas while evacuating. Next, the solidified isopentane was heated and melted. This operation was repeated until no dissolved gas was released, and isopentane was degassed and purified.
• the volatile organic compounds are adsorbed on molecular sieves (molecular sieves) that have been cooled to near the liquid nitrogen temperature in advance, heated, and heated.
• molecular sieves molecular sieves
• the gas that first desorbs from the chamber is accumulated in the gas reservoir.
• the degassed and purified isopentane vapor is introduced into a glass reservoir (volume: 15 O ml) maintained at 50 ° C ⁇ 1 ° C up to about 540 mmHg.
• Isopentane vapor was introduced from the reservoir into a glass adsorption tube that maintained the reservoir containing the adhesive at 20 ° C ⁇ 0.5 ° C, and the saturated vapor pressure of isopentane at a temperature of 20 ° C
• a pressure fluctuation of 10 minutes at a temperature of 20 ° C is a pressure of 1 to 10 times the vapor pressure at 1 atmosphere, and a pressure fluctuation of 10 minutes is 0.02 mmH g at or below the saturated vapor pressure of isopentane at 20 ° C and the equilibrium of isopentane at 20 ° C.
• the adsorption amount (m 1 / g (stp)) was used.
• FIG. 1 is a flow sheet for explaining a method of recovering gaseous hydrocarbons contained in waste gas according to an embodiment of the present invention, which employs a fixed bed type and a PSA method.
• 2a is an adsorption tower
• 2b is a desorption tower
• 3 is a vacuum pump
• 4 is a cooler
• 5 is a concentrated liquid storage container
• 6 is a recovery oil tank
• 7 is a solenoid valve
• P is a pressure gauge
• T temperature.
• Meter indicates a flow meter
• L indicates a liquid level gauge.
• the gas to be treated containing hydrocarbons is sent to the adsorption tower 2a (after switching to the desorption step, the adsorption tower 2b) via a profile not shown in the figure.
• the adsorption towers 2a and 2b are operated while alternately switching between the adsorption step and the desorption step.
• the switching time is 3 to 10 minutes.
• a purge gas for example, air
• the hydrogen hydride is desorbed.
• the desorbed gas containing the concentrated V 0 C is sent to the cooler 4 that cools to a temperature of about 20 ° C, and the unconcentrated gas (all initially) is returned to the inlet of the adsorption towers 2a and 2b .
• the concentration of the exhaust gas combined with the unconcentrated gas sent to the adsorption towers 2a and 2b is increased.
• part of the hydrocarbons in the desorbed gas is concentrated by cooling at room temperature, and recovered in the recovery oil tank 6 via the concentrated liquid storage container 5.
• the concentration of the gaseous hydrocarbon in the desorbed gas can be increased by a simple process, whereby the hydrocarbon solvent can be recovered by cooling at room temperature. .
• a cooling unit for example, for cooling to 5 ° C or less, which is extremely advantageous in terms of equipment costs and operation costs.
• the recovery method according to the embodiment of the present invention can be used for a wide range of solvent-containing gas from low to high concentrations, and therefore has extremely high industrial utility value.
• the present invention is not limited to the above embodiment.
• the adsorption tower after the completion of the adsorption step may be heated to a safe temperature by a heating exchanger.
• the amount of purge gas can be reduced, and the capacity of the vacuum pump can be reduced.
• the recovery method of the present invention in a low concentration range, the amount of adsorption and the partial pressure of the hydrocarbon solvent are almost proportional to each other, so that it is not necessary to increase the amount of adsorbent.
• a raw material gel powder having a specific surface area of 600 m 2 / g, a pore volume of 0.40 ml Z g and a raw material property of an average pore diameter of 2.5 nm was 3.2 mm (diameter) ⁇ 3. Tablets were formed into cylindrical (mm) height pellets. Next, the pellets were heated from room temperature to 550 ° C. in a Matsufur furnace at a heating rate of 1 for 1 minute, and then maintained at a temperature of 550 for 5 hours. Thereafter, the sample was cooled to room temperature to obtain the sample adsorbent of Example 1.
• the specific surface area was 57 O m 2 / g
• the pore volume was 0.38 m 1 / g
• the average pore diameter was 2.5 nm. . Therefore, the reduction rate of the specific surface area of the sample adsorbent with respect to the raw material gel powder was 5%.
• the water vapor at 20 ° C and 2 mm Hg was measured according to the method for evaluating the hydrophobizing ability described above.
• the gas saturation adsorption amount was 9.8 m 1 / g (stp). stp means the standard state (Standard Temperature and Pressure), which indicates the adsorption amount converted to 0 ° C and normal pressure.
• the isopentane adsorption amount measured after equilibrium adsorption of water at 10 ° C. at 20 ° C. according to the above-described method for evaluating the adsorption ability of V 0 C was 3.1 m 1 / g (stp).
• Example 1 The physical properties of the raw material of Example 1, the conditions of the hydrophobic treatment, the physical properties of the adsorbent, the hydrophobicity and the amount of VO C adsorbed are described in the column of Example 1 in Table 1, respectively. Hereinafter, the same applies to Examples 2 to 5.
• Example 1 Material example 2 Example 3
• Male example 4 Male example 5
• a silica gel powder having a specific surface area of 660 m 2 , a pore volume of 0.10 ml Zg and a raw material property having an average pore diameter of 0.6 nm was cast on a pellet having the same shape as in Example 1.
• the tablets were molded, heated from room temperature to 600 ° C. in a Matsufuru furnace at a heating rate of 5 ° C.Z minutes, and then kept at 600 ° C. for 4 hours. Thereafter, the sample was cooled to room temperature to obtain the sample adsorbent of Example 2.
• the specific surface area of the sample adsorbent of Example 2 was 581 m 2 , the pore volume was 0.09 m 1 Zg, and the average pore diameter was 0.6 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel was 12%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 7.5 m 1 / g (stp) and 4.5 m 1 / g (stp), respectively. Two weeks after immersion in water, no cracks occurred in the sample adsorbent.
• the specific surface area is 690 m 2 / g, the pore volume is 0.30 ml, and the average pore diameter is 2.
• a spherical silica gel having a particle size of 2 to 3 mm and having a physical property of 0 nm is heated from room temperature to 600 ° C in a muffle furnace at a heating rate of 10 ° CZ, followed by 65 ° C. At the temperature
• Example 3 The specific surface area of the sample adsorbent of Example 3 was 4488 m 2 / g, the pore volume was 0.20 m 1 Zg, and the average pore diameter was 1.8 nm. Therefore, the ratio of decrease in the specific surface area of the sample adsorbent to the spherical silica gel as the raw material was 35%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 5.3 ml / g (st ⁇ ) and 4.1 m 1 / g (stp), respectively. . Also after immersion in water
• a spherical siliceous gel with a specific surface area of 700 m 2 / g, a pore volume of 0.3 ml Zg, and an average pore diameter of 1.5 nm and a particle size of 2-3 mm with the raw material properties of a muffle furnace Then, the mixture was heated from room temperature to 700 ° C. at a heating rate of 20 ° C./min, and then kept at 700 ° C. for 3 hours. Thereafter, the sample was cooled to room temperature to obtain the sample adsorbent of Example 4.
• the specific surface area of the sample adsorbent of Example 4 0 m 2 / g, a pore volume of 0. 1 8 ml / g, and the average pore size were 1.7 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent with respect to the raw material gel was 40%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 3.2 m 1 / g (st ⁇ ) and 3.7 m 1 / g (stp), respectively. . Two weeks after immersion in water, no cracks occurred in the sample adsorbent.
• the specific surface area of the sample adsorbent of Example 5 was 6.55 rn ⁇ g, the pore volume was 0.25 m1Zg, and the average pore diameter was 1.5 nm.
• the reduction rate of the specific surface area of the sample adsorbent with respect to the raw material silica gel was 16%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 10.0 ml / g (stp) and 5.9 m 1 / g (stp), respectively. Two weeks after immersion in water, no cracks occurred in the sample adsorbent.
• Pellet having a specific surface area of 450 m 2 / g, a pore volume of 0.69 m 1 Zg, and an average pore diameter of 6.1 nm. Then, the mixture was heated from room temperature to 650 ° C at a heating rate of 10 / min in a Matsufuru furnace, and then kept at a temperature of 650 ° C for 3 hours. Then, it was cooled down to room temperature to obtain the sample adsorbent of Comparative Example 1.
• the specific surface area of the sample adsorbent of Comparative Example 1 was 3883 m 2 / g, the pore volume was 0.59 ml / g, and the average pore diameter was 6.2 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel was 15%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 7.5 m 1 / g (stp) and 1.5 m 1 (stp), respectively. Two weeks after immersion in water, no cracks occurred in the sample adsorbent.
• a spherical silica gel with a specific surface area of 65 m 2 / g, a pore volume of 0.40 ml, and an average pore diameter of 2.5 nm, which has raw material properties and a particle diameter of 2-3 mm is raised. Heating was performed from room temperature to 800 at a temperature rate of 30 ° CZ min, followed by holding at a temperature of 800 ° C for 6 hours. Thereafter, the sample was cooled to room temperature to obtain a sample adsorbent of Comparative Example 2.
• the specific surface area of the sample adsorbent of Comparative Example 2 was 280 m 2 / g, the pore volume was 0.79 ml / g, and the average pore diameter was 11.3 nm. Therefore, the rate of decrease in the specific surface area of the sample adsorbent relative to the raw material gel was 65%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 4.8 ml / g (stp) and 0.1 m 1 Z g (stp). Two weeks after immersion in water, the sample adsorbent had significant cracks.
• the specific surface area of the sample adsorbent of Comparative Example 3 was 760 m 2 , the pore volume was 0.29 m 1 Zg, and the average pore diameter was 3. O nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel was 3%.
• the water vapor saturated adsorption amount and isopentane adsorption amount obtained in the same manner as in Example 1 were 26.6 m 1 / g (stp) and 0.3 ml Zg (stp), respectively. Two weeks after immersion in water, the sample adsorbent had been powdered.
• a specific surface area of 6 9 0 m 2 / g pore volume of 0. 3 0 m 1 / g, a muffle furnace spherical silica force gel (2 ⁇ 3 mm diameter) having an average pore diameter has a material property of 2. 0 nm
• the mixture was heated from room temperature to a temperature rising rate of 10 ° C. Zmin, heated to 800 ° C., and kept at the same temperature for 3 hours. Then, it was cooled to room temperature to obtain the sample adsorbent of Comparative Example 4.
• the specific surface area of the sample adsorbent of Comparative Example 4 was 248 m 2 Zg, the pore volume was 0.32 ml Zg, and the average pore diameter was 5.2 nm. Therefore, the decrease rate of the specific surface area of the sample adsorbent relative to the raw material silica gel was 64%.
• the water-saturated adsorption amount at 20 ° C and 2 mmHg showing hydrophobizing ability was 4.8 m1Zg (stp), and no crack was observed after 2 weeks of immersion in water. .
• the isopentane adsorption amount after equilibrium adsorption of 10 mmHg of water at 20 ° C was 0.2 ml Zg (stp).
• the specific surface area is 780 m 2 / gs
• the pore volume is 0.30 m 1 / g and the average pore diameter is 1.5 nm.
• the mixture was heated at 5 ° C / min, heated to 500 ° C, and kept at the same temperature for 3 hours. afterwards After cooling to room temperature, the sample adsorbent of Comparative Example 5 was obtained.
• the specific surface area of the sample adsorbent of Comparative Example 5 was 755 m 2 Z g, the pore volume was 0.29 ml Z g, and the average pore diameter was 1.5 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel was 3%. Further, the water vapor saturated adsorption amount at 20 ° C and 2 mmHg showing hydrophobicity was 25.8 ml Zg (stp), and powdered after 2 weeks from immersion in water. At 20 ° C., the amount of isopentane adsorbed after equilibrium adsorption of water at 10 mmHg was 0.2 ml Zg (stp).
• the specific surface area of the sample adsorbent of Comparative Example 6 was 390 m 2 Z g, the pore volume was 0.60 ml Z g, and the average pore diameter was 6.2 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel was 40%.
• the water vapor saturated adsorption amount at 20 ° C. and 2 mmHg showing hydrophobizing ability was 3.7 ml / g (stp), and cracks were generated two weeks after immersion in water.
• the adsorption amount of isopentane after equilibrium adsorption of water at 10 ° C at 20 ° C was 1. S ml Zg C stp).
• the amount of adsorbed V 0 C of all the examples was at least twice the amount of adsorbed V 0 C of the comparative example.
• the sample adsorbent of the comparative example was powdered or cracked.
• Comparative Example 1 showed good hydrophobizing ability because it was subjected to the hydrophobizing treatment under the conditions specified in the present invention, but the specific surface area, the pore volume, and the average pore diameter were out of the specific ranges of the present invention, respectively. In addition, VOC adsorption capacity is poor.
• Comparative Example 2 although the raw material properties of the raw material silica gel were within the specific range of the present invention, the conditions for water-phobic treatment, that is, the heating rate and the heat treatment temperature, exceeded the upper limits of the ranges specified in the present invention, respectively. In addition, sintering or distortion occurred in the gel, and as a result, although the water vapor adsorption amount was relatively low, the V 0 C adsorption capacity was extremely poor, and cracks occurred in the sample adsorbent.
• Comparative Example 4 although the raw material properties were the same as those in Example 3, the hydrophobizing treatment temperature was 800 ° C., which was higher than the upper limit of the temperature range specified in the present invention. Accordingly, although the adsorption material is made hydrophobic, the specific surface area of the obtained sample adsorbent does not reach the lower limit of the range specified in the present invention because the specific surface area reduction rate is extremely large, so that sufficient V No 0 C adsorption amount was obtained, and the product was ineligible as an adsorbent.
• Comparative Example 5 although the raw material properties were the same as in Example 5, the hydrophobizing treatment temperature was 5200C, which was lower than the lower limit of the temperature range specified in the present invention. As a result, the specific surface area is reduced in order to maintain the material properties. However, the hydrophobicity is insufficient due to the low temperature range, the amount of adsorbed water vapor is extremely large, and the sample adsorbent immersed in water is significantly powdered. As a result, the VOC adsorption amount was also extremely low. In Comparative Example 6, although the raw material properties were within the range specified in the present invention, the heating rate during the hydrophobization treatment was 30 ° C / min, which was higher than the upper limit of the heating rate range specified in the present invention. Great.
• the adsorbent is in a situation where distortion is likely to occur. Since the heat treatment temperature was within the specified value, the surface was hydrophobized in terms of the amount of water adsorbed, but cracks occurred when immersed in water due to the large amount of distortion. The VOC adsorption amount was also unsatisfactory, and was unsuitable as an adsorbent.
• the hydrophobizing ability was increased to a temperature in the range of 550 to 700. Achieved at a heating rate of 1 to 20 ° C / min and maintained at the same temperature range for 2 to 5 hours to effectively develop.
• a silylation gel whose raw material properties are within the specified range of the present invention, It is possible to obtain an adsorbent exhibiting good hydrophobicity such as crack resistance against water and water repellency and high V0c adsorption ability.
• V 0 C As one of the factors indicating the V 0 C adsorption ability, the V 0 C selectivity of the sample adsorbent was measured.
• V 0 C was specified as shown in Tables 3 and 4, and VOC selectivity was measured according to the method described above. The results shown in Tables 3 and 4 were obtained.
• the VOC selectivity was measured for three types of VOC.
• the sample adsorbents of Examples 1 to 5 had VOC selectivities of 85% or more and 74% or less. Compared with the VOC selectivity of Comparative Example 6, the V0C selectivity is much higher. From the test using the sample adsorbent of Example 3, it is found that the sample adsorbent of Example 3 shows almost the same V0C selectivity even when the type of VOC is different.
• 35 g of a silica gel powder having a specific surface area of 52 m 2 / g, a pore volume of 0.70 m 1 Zg and an average pore diameter of 5.0 nm and having raw material properties of 5.0 nm was weighed, and succinic acid was removed. After adding 15 g and thoroughly dry-kneading in an automatic mortar, the mixture was tablet-formed into a 3 mm (diameter) x 3 mm (height) cylindrical pellet by a tableting machine.
• the pellet was heated from room temperature to 450 at a heating rate of 0.5 ° CZ for 0.5 hour in a Matsufur furnace, and then kept at 450 ° C for 3 hours. Thereafter, the sample was cooled to room temperature to obtain the sample adsorbent of Example 6.
• the sample adsorbent had no cracks.
• the isosopene reversible adsorption amount (5Q) at 20 ° C was 8.0 m 1 / g (stp). Met.
• Example 6 The physical properties of the raw material of Example 6, the conditions for the hydrophobizing treatment, the physical properties of the adsorbent, the hydrophobizing ability, and the amount of adsorbed VOC are described in the column of Example 6 in Table 5, respectively. Hereinafter, the same applies to Examples 7 to 11 and Comparative Examples 7 to 10.
• a specific surface area of 5 5 O m 2, 4 an average particle size 2.5 ⁇ spherical silica force gel pore volume 0. 6 0 m 1 / g and an average pore diameter has a material property of 4. 3 nm 0
• the mixture was heated in air at a temperature of 400 ° C. for 60 minutes, then left to cool to room temperature and cooled.
• Example 7 When the physical properties of the sample adsorbent of Example 7 were measured, the specific surface area was 54 O m 2 , the pore volume was 0.6 m 1 / g, and the average pore diameter was 4.5 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent with respect to the raw material silica gel powder was 1.8%.
• the equilibrium water vapor adsorption amount was 7.5 m 1 / g (stp), and no cracks occurred in the sample adsorbent after 2 weeks of immersion in water.
• the reversible adsorption amount of isopentane ((5Q) was 8.5 m1Zg (stp).
• PA propionaldehyde
• Example 8 This was placed in a constant temperature drier maintained at about 100 ° C to remove water, and then heated to 500 ° C at an average heating rate of 3 ° C / min, and then heated to 500 ° C. Temperature for 3 hours. Thereafter, the mixture was cooled to room temperature to obtain a sample adsorbent of Example 8.
• the specific surface area was 670 m 2 / g
• the pore volume was 0.4 m 1 Zg
• the average pore diameter was 2.1 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent with respect to the silica gel powder as the raw material was 2.9%.
• the equilibrium water vapor adsorption amount is 9. 9. ml / g (stp), and immersed in water for 2 weeks Even after the lapse of time, no cracks occurred in the sample adsorbent.
• the isopentane reversible adsorption amount (Q) was 10.5 m 1 / g (stp).
• silica gel powder having a specific surface area of 690 m 2 / g, a pore volume of 0.3 m 1 / g, and an average pore diameter of 2.0 nm and having raw material properties was weighed, and carboxymethyl After adding 2.5 g of cellulose (CMC) and thoroughly dry-kneading in an automatic mortar, the mixture was tablet-formed into a 3 mm (diameter) x 3 mm (height) cylindrical pellet using a tableting machine. .
• CMC cellulose
• the pellet was heated from room temperature to 680 at a heating rate of 7 ° CZ in a muffle furnace, and then kept at a temperature of 680 ° C for 3 hours. Thereafter, the mixture was cooled to room temperature to obtain a sample adsorbent of Example 9.
• the specific surface area was 5 17 m 2 / g
• the pore volume was 0.3 m 1 / g
• the average pore diameter was 2.3 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent with respect to the silica gel powder as the raw material was 25.1%.
• the equilibrium water vapor adsorption was 7.3 m 1 Z g (stp), and no cracks occurred in the sample adsorbent even after 2 weeks of immersion in water. Isopentane reverse adsorption ((5 q) was 8.2 m 1 / g (stp).
• the pellets were then heated in a Matsufuru furnace from room temperature to 75 ° C. at a rate of 10 / minute from room temperature and subsequently maintained at a temperature of 75 ° C. for 3 hours. Thereafter, the mixture was cooled to room temperature to obtain a sample adsorbent of Example 10.
• Example 10 45 g of silicic acid gel powder having the same raw material properties as in Example 10 was weighed, 5 g of carboxyl methyl cellulose (CMC) was added, and the mixture was thoroughly dry-kneaded in an automatic mortar. Tablets were formed into cylindrical pellets of mm (diameter) x 3 mm (height).
• CMC carboxyl methyl cellulose
• the pellets were heated from room temperature to 63 ° C at a heating rate of 20 / min in a Matsufuru furnace, and then kept at a temperature of 63 ° C for 3 hours. Thereafter, the sample was cooled to room temperature to obtain the sample adsorbent of Example 11.
• the specific surface area was 597 mVg
• the pore volume was 0.3 m1Zg
• the average pore diameter was 2.0 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent with respect to the raw material silica gel powder was 23.5%.
• the equilibrium water vapor adsorption was 9.4 m 1 / g (stp), and no cracks occurred in the sample adsorbent even after 2 weeks of immersion in water.
• the reversible adsorption amount ((q)) of isopentane was 9.4 m 1 / g (stp).
• a spherical silica gel having an average particle size of 2.5 mm having the same raw material properties as in Example 6 was heated to 400 ° C. in air at an average heating rate of 25 ° C.Z, and subsequently 400 ° C. It was kept at the temperature of C for 1 hour. Thereafter, the sample was cooled to room temperature to obtain a sample adsorbent of Comparative Example 7.
• the specific surface area was 500 m 2 / g
• the pore volume was 0.7 m 1 / g
• the average pore diameter was 5.2 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel powder was 3.8%.
• the equilibrium water vapor adsorption amount was 25.1 m 1 / g (stp), and the sample adsorbent had cracked two weeks after immersion in water.
• the isopentane reversible adsorption (SQ) was 8.0 m 1 / g (stp).
• Example 8 Average particle size having the same raw material properties as in Example 10 and Example 11
• the licagel was heated in air at an average heating rate of 10 ° C / min to 75 ° C and subsequently maintained at a temperature of 75 ° C for 1 hour. Thereafter, the mixture was cooled to room temperature to obtain a sample adsorbent of Comparative Example 8.
• Example 9 The pellets obtained in the same manner as in Example 9 were heated in a matsufurn furnace from room temperature to 300 ° C at a rate of temperature increase of 3 ° C / min, and then maintained at a temperature of 300 ° C.
• a sample adsorbent of Comparative Example 9 was obtained in the same manner as Example 9 except for the following.
• the specific surface area was 680 m 2 / g
• the pore volume was 0.3 m 1 / g
• the average pore diameter was 2.0 nm. Therefore, the reduction rate of the specific surface area of the sample adsorbent relative to the raw material silica gel powder was 1.4%.
• the equilibrium water vapor adsorption was 18.0 m 1 / g (stp), and the sample adsorbent had cracked two weeks after immersion in water. Isopentane reversible adsorption ( ⁇ 5 Q) was 1.0 m 1 / g (stp).
• spherical silica gel having the same material properties as in Example 7 was weighed, 1.0 g of polyvinyl alcohol (PVA) was added, and the mixture was thoroughly dry-kneaded in an automatic mortar and then a tableting machine. Into a 3 mm (diameter) x 3 mm (height) cylindrical pellet.
• PVA polyvinyl alcohol
• the pellets were heated from room temperature to 800 ° C at a heating rate of 20 ° CZ in a Matsufur furnace, and then kept at 800 ° C for 3 hours. Thereafter, the mixture was cooled to room temperature to obtain a sample adsorbent of Comparative Example 10.
• Example 6 to 11 the water vapor adsorption amount was 9.7 m 1 / g (stp) or less, no cracking occurred when immersed in water, and the isopentane reversible adsorption amount was 5. 9 ml / g (stp) or more. Therefore, the sample adsorbents of Examples 6 to 11 can be evaluated as suitable adsorbents as VOC-PSA adsorbents.
• Examples 6 to 8 show that by adding the second component, the hydrophobic effect can be exhibited while maintaining the physical properties of the raw material substantially by the heat treatment in a low temperature range.
• Example 7 used a silica gel having substantially the same physical properties as the raw material of the silica gel of Comparative Example 6, and the effect of adding the second component when heat treatment was performed at a low temperature range of 400 as in Comparative Example 6. It shows.
• Example 2 in which the second component was added, the amount of water vapor adsorption was as low as about 1/3 (7.5 m 1 / g (stp)) of Comparative Example 1, and no cracking occurred during immersion in water. This indicates that the addition of the second component imparts hydrophobizing ability and improves the strength as an adsorbent.
• the specific surface area reduction rates of Example 7 and Comparative Example 7 were 1.8% and 3.8%, respectively, and although the differences were not large, the specific surface area reduction rates due to the addition of the second component were small. A significant reduction effect is observed.
• Example 9 is an example in which the heat treatment was performed near the upper limit of the temperature range of 680 ° C., and shrinkage due to heating occurred so that the specific surface area reduction rate was 25.1%. It is considered something. However, in Comparative Example 8 where the heat treatment temperature was similarly high, the second component was not used. Since the high-temperature treatment was performed without the addition, the specific surface area reduction rate was close to 69%, and the average pore diameter was enlarged, and the micropores were reduced. From a comparison between Example 9 and Comparative Example 8, it can be seen that when heat treatment is performed in a high temperature range exceeding 500 ° C., the second component has a high effect of maintaining the physical properties of the raw material.
• Example 11 is an example in which the second component was added to a silica gel raw material having the same raw material properties as in Example 10, and heat treatment was performed at a preferable temperature. Compared with Example 10, the specific surface area reduction rate was small, and the VOC adsorption ability and the hydrophobizing ability were excellent. Comparative Example 7 and Comparative Example 10, which have a large amount of reversible adsorption of isopentane, have twice or more the amount of water vapor adsorption as compared with the Example, while Comparative Example 8 and Comparative Example 10, which have a small amount of water vapor adsorption, have a large amount of water vapor adsorption. Is significantly smaller than the embodiment.
• Comparative Example 10 contains the second component and therefore has hydrophobicity, but the heat treatment temperature is too high, the silica gel shrinks significantly, and the specific surface area reduction rate is 58. Reached 4% and the V0C reversible adsorption amount is small. However, Comparative Example 8, in which the second component was not added, had a specific surface area reduction rate of 68.9%, which indicates that Comparative Example 10 had an effect of adding the second component. .
• Comparative Example 7 and Example 6 differ in the shape of the silica gel and the heat treatment conditions, but have the same raw material properties of the silica gel.
• Comparative Example 7 in which the second component was not added the amount of water vapor adsorbed was about four times that of Example 6.
• the specific surface area reduction rates of Comparative Example 7 and Example 6 are 3.8% and 2.5%, respectively.
• Comparative Example 7 in which the second component was not added cracks occurred during immersion in water.
• Comparative Example 8 and Example 10 were both examples in which the heat treatment temperature was set to the upper limit of 750 ° C. Although the shape of the silica gel was different, the raw material properties of the silica gel were the same. Although the temperature holding time in the heat treatment step is also different, Comparative Example 8 is significantly different from Example 10 in that the second component is not added.
• Example 10 and Comparative Example 8 were close to 42.3% and 69%, respectively.
• the average pore diameter of Example 10 was 2.3 nm, which was slightly larger than 1.7 nm of the raw material gel, but the average pore diameter of Comparative Example 8 was significantly large, at 8.2 nm. It is getting worse.
• the water vapor adsorption amount of Comparative Example 8 was about 1 Z 2 of Example 10, but the reversible adsorption amount of isopenne was about 1 Z 3 of Example 10.
• Comparative Example 9 and Example 9 have the same raw material physical properties of silica gel and the same type and amount of the second component, but the temperature of the heat treatment step is 300 ° C. in Comparative Example 9 and 7 in Example 9. It is significantly different from 50 ° C., and therefore, Comparative Example 9 has about 2.5 times the amount of water vapor adsorption as Example 9. This demonstrates that the temperature of the heat treatment process is important.
• Comparative Example 9 and Example 8 have the same raw material properties of the silicone gel, and the second component is also added. This is an example showing the effect of the case where the average heating rate is the same and the heat treatment temperature is different between the two components to which the second component is added, and the irreversible adsorption amount of isopentane is satisfactory in both cases.
• Comparative Example 9 where the heat treatment was performed at 300 ° C lower than the predetermined heat treatment temperature, the water vapor adsorption amount was as high as 18.0 m 1 / g (stp), and cracks occurred when immersed in water. It is not suitable as an adsorbent.
• Example 8 is an excellent adsorbent having both high hydrophobizing ability and VOC adsorption ability.
• Comparative Example 10 and Example 7 were the same in that the raw material properties of the silica gel were the same and the types were different, but the addition of the second component was the same. Within the specified range. However, the temperature of the heat treatment step was significantly different from 800 ° C. in Comparative Example 10 and 400 ° C. in Example 7, so that Comparative Example 10 had a low reversible adsorption amount of isopentane in Example 2. Less than 12 This demonstrates that the temperature of the heat treatment process is important. The temperature of the heat treatment step can also be seen from the comparison between Comparative Example 9 and Example 8.
• the hydrophobicity can be imparted even by heat treatment in a low temperature range, and a decrease in raw material properties due to the heat treatment can be suppressed in a high temperature range. .
• the requirements for the raw material properties required for the raw material silica gel are relaxed, and the selection range of the raw material silica gel is expanded, so that a cheaper silica gel can be used.
• the adsorbents of the examples have excellent hydrophobicity, so that the mechanical strength of the adsorbents can be maintained for a long period of time. Can be operated stably while maintaining high recovery performance for a long period of time.
• VOC selectivity of the sample adsorbent was measured.
• V 0 C was specified as shown in Table 6, and the VOC selectivity was measured according to the method described above. The results shown in Table 6 were obtained.
• the sample adsorbents of Examples 6 to 11 had VOC selectivities of 85% or more and 74% or less of Comparative Examples 7 to 10.
• the VOC selectivity is much higher than the C selectivity.
• Example 6 and Comparative Example 10 Comparison of the sample adsorbents of Example 6 and Comparative Example 10, which adsorb the same V 0 C, comparison of the sample adsorbents of Example 8 and Comparative Example 7, and comparison of the sample adsorbents of Example 9 and Comparative Example 8 From comparison, and comparison of the sample adsorbents of Example 11 and Comparative Example 9, in all cases of VOC, the sample adsorbent of the Example was 15 3 1 to 20% lower than the sample adsorbent of the Comparative Example. The V 0 C selectivity of about% higher is shown.
• the molded silica gel was heated from normal temperature to 500 ° C. at a heating rate of 2 ° C.Z for 5 hours, and heated in air at 500 ° C. for 5 hours.
• the impregnated silica gel compact is dried in an oven at 110 for 15 hours, and further heated in a carbon monoxide atmosphere using an electric furnace to a temperature rising rate of 2 ° CZ to 350 ° C for 2 minutes. The temperature was raised and a heat treatment was performed at a temperature of 350 ° C. for 15 hours.
• the surface area was 590 m 2 Z g
• the average pore diameter was 1.5 11 111
• the pore volume was 0.32 ml / g. Met.
• the saturated adsorption amount of water vapor measured in accordance with the above-described method for evaluating the hydrophobizing ability is 17.8 m1 Zg, and the above-mentioned evaluation of the VOC adsorption ability is performed.
• the reversible adsorbed amount of isopenene measured according to the method was 9.1 ml Zg.
• the adsorbent did not crack in the immersion test using distilled water described above.
• Example 12 The raw material properties, processing conditions, adsorbent properties, saturated adsorption amount of water vapor and reversible adsorption amount of isopentane of the sample adsorbent of Example 12 are described in the columns of Example 12 in Table 7, respectively. I have. Hereinafter, the same applies to Examples 13 to 20 and Comparative Examples 11 to 15.
• Example 12 710 1.5 A 500 1000 350 590 1.5 17.8 9.1 None
• Example 13 710 1.5 A 550 500 350 570 1.5 12,2 9.2 None
• Example 14 710 1.5 B 600 1000 500 510 1.5 8.4 8.5 None
• Example 15 710 1.5 A 680 3000 500 420 1.5 4.8 7.7 None
• Example 16 690 1.5 A 500 550 550 1.5 10.5 9.0 None
• Example 17 690 1.5 C 2000 500 570 1.5 16.1 8.8 None
• Example 18 840 1.3 B 3000 680 460 1.2 8.8 9.5 None
• Example 19 580 1.3 D 550 500 350 520 1.3 8.9 8.4 None
• Example 1 the same silica dim moldings and 1 0 0 g, the aluminum nitrate two ⁇ beam nonahydrate ( ⁇ 1 ( ⁇ 0 3) 3 ⁇ 9 ⁇ 2 0) 1. were weighed 2 4 g, respectively.
• the molded product was heated from room temperature to 550 ° C at a heating rate of 2 ° CZ for 5 hours and heated in air at 550 ° C for 5 hours.
• the heat-treated siliceous gel body was immersed in the prepared aqueous solution, and Left for hours.
• the impregnated silica gel compact is dried in an oven at 110 ° C for 15 hours, and further heated to 350 ° C at a rate of 2 ° C / min in air using an electric furnace. Then, it was heated at a temperature of 350 ° C. for 15 hours.
• the surface area was 570 m 2 Z g
• the average pore diameter was 1.5011
• the pore volume was 0.30 ml / g. Met.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 12.2 ml / g and 9.2 mlZg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• the molded product of silicon gel was heated from normal temperature to 600 ° C at a heating rate of 2 ° CZ for 5 hours in air at a temperature of 600 ° C.
• the total amount of the weighed zirconium nitrate dihydrate was dissolved in 100 ml of distilled water to prepare an aqueous solution. Then, the heat-treated silica gel compact was immersed in the prepared aqueous solution and allowed to stand for 15 hours. . Next, the impregnated silica gel compact is dried in an oven at 110 ° C for 15 hours, and further heated to 500 ° C in an electric furnace under vacuum at a rate of 2 ° C for 2 minutes. Then, heat treatment was performed at a temperature of 500 ° C. for 3 hours.
• a silica gel-based adsorbent having an atomic ratio of 100: 1 was obtained as the sample adsorbent of Example 14.
• Adsorbent physical properties of the Example 1 4 samples adsorbent and the measured time, surface area 5 1 0 m 2 Z g, an average pore diameter of 1.5 11 111, a pore volume of 0. 2 7 ml / g.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 8.4 ml / g and 8.5 ml / g, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• Example 2 The same silica force gel moldings as in Example 1 2 1 0 0 g, was weighed 0. 2 1 g each aluminum nitrate two ⁇ beam nonahydrate ( ⁇ 1 ( ⁇ 0 3) 3 ⁇ 9 ⁇ 2 0).
• the molded product was heated from room temperature to 680 ° C at a heating rate of 2 ° C / min, and heated in air at 680 ° C for 3 hours.
• the total amount of the weighed aluminum nitrate nonahydrate was dissolved in 100 ml of distilled water to prepare an aqueous solution, and the heat-treated siliceous gel formed body was immersed in the prepared aqueous solution. Left for hours.
• the impregnated silica gel compact was dried in an oven at 110 ° C for 15 hours, and further heated to 500 ° C at a rate of 2 ° C in a carbon monoxide atmosphere using an electric furnace. The mixture was heated at 500 ° C. for 3 hours.
• the surface area was 420 m2 Zg
• the average pore diameter was 5111
• the pore volume was 0.23 ml Zg.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 4.8 ml Zg and 7.7 ml / g, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• the prepared aqueous solution and the total amount of the weighed powdery silica gel are automatically measured.
• the mixture was wet-kneaded in a mortar for 30 minutes. Then, the kneaded mixture is oven The mixture was dried at 110 ° C. for 15 hours, and then the obtained mixed powder was tableted and formed into a cylindrical tablet having a diameter of 2.0 mm and a height of 3.0 mm.
• the molded body was heated to 550 ° C. at a rate of 2 ° C.Z in an electric furnace and heated at 550 ° C. for 5 hours in a carbon monoxide atmosphere.
• the surface area was 550 m 2 Z g
• the average pore diameter was 1.5 11 111
• the pore volume was 0.29 ml Zg. there were.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 10.5 ml Zg and 9 • O ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• Example 2 The same powdery silica force gel as in Example 1 6 1 0 0 g, 4 0% aqueous solution of titanium sulfate (Ti (S0 4) 2 aq ) 0. 5 0 g of were weighed.
• the total amount of the weighed 40% titanium sulfate aqueous solution and the total amount of the weighed powdery silica gel were wet-kneaded in an automatic mortar for 10 minutes. Subsequently, the kneaded mixture was dried in an oven at 110 ° C. for 15 hours, and then the obtained mixed powder was compressed into a tablet having a diameter of 2.0 mm and a height of 3.0 mm. Molded. The molded body was heated to 500 ° C. in a carbon monoxide atmosphere at a temperature increasing rate of 2 ° C.Z for 5 hours using an electric furnace at a temperature of 500 ° C. for 5 hours.
• the adsorbent physical properties of the obtained sample adsorbent of Example 17 were measured, and it was found that the surface area was 570 m 2 Zg, the average pore diameter was 1.5 ⁇ 11, and the pore volume was 0.30 ml Zg. Was.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 16.1 ml Zg and 8.8 ml Zg, respectively.
• the adsorbent also showed a cracking force in the immersion test using distilled water.
• the total amount of the weighed zirconium nitrate dihydrate and the total amount of the weighed silica gel were dry-kneaded for 10 minutes in an automatic mortar. Subsequently, the obtained mixed powder was tableted and formed into a cylindrical tablet having a diameter of 2.0 mm and a height of 3.0 mm. The compact was heated to 680 ° C at a rate of 2 ° CZ in air using an electric furnace, and was heated at 680 ° C for 3 hours.
• the surface area was found to be 460 m 2 Z g, the average pore diameter was 1.2 11 111, and the pore volume was 0.20 ml Zg. there were.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 8.8 ml / g and 9.5 ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• the molded silica gel was heated from room temperature to 550 ° C at a heating rate of 2 ° CZ for 3 hours, and heated in air at 550 ° C for 3 hours.
• the total amount of the weighed aluminum lactate was dissolved in 100 ml of distilled water to prepare an aqueous solution, and then the heat-treated silica gel compact was immersed in the prepared aqueous solution and allowed to stand for 15 hours.
• the impregnated silica gel molded body is dried in an oven at 110 ° C for 15 hours, and further heated in air using an electric furnace at a temperature rising rate of 2 ° C to 350 ° C for 2 minutes. The temperature was raised and heat treatment was performed at 350 ° C. for 5 hours.
• Adsorbent physical properties of the Example 1 9 sample adsorbent was measured, surface area 5 2 0 m 2 / g, an average pore diameter of 3 11 111, and a pore volume of 0. 2 7 ml Zg .
• water The saturated adsorption amount and the reversible adsorption amount of isopentane were 9. gml / g and 8.4 ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• the molded product of silicon gel was heated from normal temperature to 600 ° C at a heating rate of 2 ° CZ for 5 hours in air at a temperature of 600 ° C.
• the heat-treated siliceous gel formed body was immersed in the entire amount of the weighed 40% titanium sulfate aqueous solution, and allowed to stand for 15 hours.
• the impregnated silica gel compact was dried in an oven at 110 ° C for 15 hours, and further heated to 500 ° C at a rate of 2 ° C / min in a nitrogen atmosphere using an electric furnace. And heated at 500 ° C. for 5 hours.
• the surface area was 500 m2 Zg
• the average pore diameter was 3.411 1.1
• the pore volume was 0.54 ml Zg.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 8.7 ml Zg and 8.4 ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• Example 1 2 and the same silica dim moldings as Comparative Example 1 1 of the sample adsorbent was measured for its adsorbent properties, surface area 7 1 0 m '2 / g , an average pore size of 1.
• the pore size was 5 nm and the pore volume was 0.37 ml Zg.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 64. 1 ml / g and 8.9 ml Zg, respectively. When this adsorbent was immersed in distilled water, it cracked and shattered.
• Example 1 2 the same silica force gel shaped body 1 0 0 g, aluminum nitrate two ⁇ beam nonahydrate ( ⁇ 0 3) 3 ⁇ 9 ⁇ 2 0) were weighed 0. 1 2 g, respectively. Next, the molded product of silicon gel was heated from room temperature to 75 ° C. at a heating rate of 2 ° C.Z for 5 hours in a muffle furnace, and heated in air at 50 ° C. for 5 hours.
• the total amount of the weighed aluminum nitrate nonahydrate was dissolved in 100 ml of distilled water to prepare a water solution. Then, the heat-treated sintered gel body was immersed in the prepared aqueous solution. Left for 5 hours. Next, the impregnated silica gel compact was dried in an oven at 110 for 15 hours, and further heated to 500 ° C. in an electric furnace under vacuum at a rate of 2 ° C. for 2 minutes. Heat treatment was performed at 500 ° C. for 3 hours.
• the adsorbent properties of the resulting comparative Example 1 2 sample adsorbent was measured, surface area 2 9 0 m 2 Roh g, an average pore diameter of 1.5 11 111, with a pore volume of 0. 1 5 ml Zg there were.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 3.9 ml / g and 3.5 ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• the siliceous gel compact was heated from normal temperature to 450 ° C at a heating rate of 2 ° CZ for 5 hours in air at 450 ° C.
• Comparative Example 14 was carried out in the same manner as in Example 16 except that the atomic ratio was 100: 1, and the temperature of the heat treatment after molding into a cylindrical tablet was 680. A sample of the adsorbent was obtained.
• the surface area was 330 m 2 Zg
• the average pore diameter was 5 111
• the pore volume was 0.22 ml Zg.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 3.3 ml Zg and 5.1 ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• the entire amount of the weighed zirconium nitrate dihydrate and the total amount of the weighed powdered silica gel were dry-kneaded for 10 minutes in an automatic mortar. Subsequently, the obtained mixed powder was tableted and formed into a cylindrical tablet having a diameter of 2.0 mm and a height of 3.0 mm.
• the molded body was heated to 500 ° C. at a heating rate of 2 ° C. using an electric furnace, and was heated at 500 ° C. in air for 5 hours.
• the adsorbent properties of the resulting comparative Example 1 5 sample adsorbent was measured, surface area 3 4 0 m 2 Zg, average pore diameter of 5.2 11 111, with a pore volume of 0. 6 5 ml / g there were.
• the saturated adsorption amount of water and the reversible adsorption amount of isopentane were 17.4 ml Zg and 4.7 ml Zg, respectively.
• the adsorbent did not crack in the immersion test using distilled water.
• Example 12 to 20 containing the metal specified in the present invention at the specified atomic ratio and having the adsorbent characteristics specified in the present invention, the reversible adsorption amount of isopentane was 7.7 mg / 1 or more.
• the saturated adsorption amount of water vapor is 17.8 mg / l or less, and both hydrophobizing ability and V 0 C adsorption ability are superior to conventionally known adsorbents.
• the reversible adsorption amount of isopentane was 7.7 mgZl or more, regardless of the magnitude of the SiZM ratio.
• the saturated adsorption amount of water is less than 16 lmgZl.
• the reversible adsorption amount of isopentane was large and the saturated adsorption amount of water was small.
• the reversible adsorption amount of isopentane was 8.4 mg / l or more regardless of the heating temperature, and The saturated adsorption amount of water vapor is 12.2 mg / 1 or less.
• Example 12 since the heating temperature was low and the SiZM ratio was 100, the saturated adsorption amount of water was the highest among the examples. On the other hand, in Example 13 in which only the S i / M ratio was different from that in Example 12, since the S i / M ratio was 500, the saturated adsorption of water vapor was higher than that in Example 12. The amount is much less.
• the adsorbent containing no metal specified in the present invention has a remarkably large amount of saturated adsorption of water, easily generates cracks, has poor water resistance, and practically speaking. Unavailable.
• Comparative Examples 12, 14, and 15 The adsorbents not having the adsorbent characteristics specified in the present invention have, as shown in Comparative Examples 12, 14, and 15, the saturated adsorption amount of water is almost the same as that of the Examples, but the reversible adsorption amount of isopentane is Significantly less than in the examples and difficult to put to practical use.
• Comparative Example 5 contained the metal specified in the present invention at the specified S i / M ratio and was subjected to the heat treatment specified in the present invention, but the specific surface area of the starting silica gel was remarkably small, and the average Due to the large pore size, the physical properties of the adsorbent are out of the range specified in the present invention, and as a result, the saturated adsorption amount of water is large.
• the adsorbents not subjected to the heat treatment specified in the present invention have the same reversible adsorption amount of isopenene as in the example, but the saturated adsorption amount of water in the example is lower than that in the example.
• the cracks are remarkably large, cracks easily occur, the water resistance is poor, and it is difficult to put to practical use.
• the heating temperature is low, the amount of water vapor adsorbed is large, cracks are easily generated, and the water resistance is poor.
• the amount of adsorbed isopentane is reduced, so that it is not preferable as a V 0 C adsorbent.
• Comparative Example 13 contains the metal specified in the present invention at the specified SiZM ratio, so although the water resistance is improved as compared with Comparative Example 11, the heating temperature is too low. Since the amount of water vapor adsorbed is larger than in Examples 12 to 20 and the water resistance is poor, it is not preferable as the V0C adsorbent.
• Comparative Example 12 Although the metal specified in the present invention was contained, the SiZM ratio was larger than the SiZM ratio specified in the present invention, that is, the content was too small, so that The effect of the genus addition is hardly exhibited.
• the adsorbent of the present invention has a higher VOC adsorption capacity than the Comparative Examples. Equivalent or excellent, while hydrophobicity is excellent.
• VOC VOC selectivity
• the sample adsorbents of Examples 12 to 20 had a VOC selectivity of 80% or more and 73% or less in Comparative Examples 11 to 14.
• the V 0 C selectivity is much higher than the V 0 C selectivity.
• Example 13 and Comparative Example 13 Comparison of the sample adsorbents of Example 13 and Comparative Example 13 which adsorb the same VOC Comparison of sample adsorbents of Example 14 and Comparative Example 11; comparison of sample adsorbents of Example 15 and Comparative Example 12; Example 15 and Comparative Example 14; and Example 17 and Comparative Example From the comparison of the sample adsorbents in Fig. 15, in all VOCs, the sample adsorbent of the example is 17% to 55% higher than the sample adsorbent of the comparative example. In particular, the sample adsorbent of Example 14 showed a higher V 0 C selectivity of 55% or more compared to the sample adsorbent of Comparative Example 11 with respect to isopentane.
• FIG. 1 a gas containing a flow rate of 10 to 25 liters / minute and a toluene concentration of 1, 000 ppm was treated.
• the operating conditions were as follows, and all were sequence control.
• Adsorbent Hydrophobic silicic acid gel
• Cooler water cooling, temperature 10 ° C
• the toluene concentration in the first raw material gas was 1,000 ppm, and no drop of condensate was stored in the storage vessel 5, and the entire amount was returned to the inlet of the adsorption tower.
• the concentration of toluene during degassing reached 150,000 ppm 240 minutes after the start of operation, and condensate started to accumulate in the storage container 5.
• air containing moisture at a pressure of 40 ppm or less and containing toluene vapor is supplied to the atmosphere. Released. Industrial applicability
• the adsorbent according to the present invention can be used in the atmosphere from small general VOC emission sources such as gasoline stand, fuel oil shipping facilities, oil depots, cleaning industry, and painting industry. It is useful for the technology to recover the discharged VOC. When used in combination with cooling and condensing, practical recovery effects can be obtained with simple equipment that does not require equipment such as chili bun gnit.

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