GB1578865A - Method for removing ammonia and/or amines from a gas containing the same - Google Patents

Description

(54) METHOD FOR REMOVING AMMONIA AND/OR AMINES FROM A GAS CONTAINING THE SAME (71) We, KUREHA KAGAKU KOGYO KABUSHIKI KAISHA, a company organized under the laws of Japan, of No. 8 Horidame-cho 1-chome Nihonbashi Chuo-ku, Tokyo, Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention concerns a method for removing ammonia and/or amines from a gas containing the same.

In recent years, regulations concerning environmental pollution in the form of disagreeable odor have become more strict. Several apparatus and deodorants have been prepared for deodorizing gases and for releasing the deodorized gases into the atmosphere. One typical proposal is a deodorizing apparatus which directly burns the gas; another is an apparatus which catalytically burns the gas. However, in operation, both these apparatus require the temperature of the gas under treatment to be raised to about 300-10000C. As a result, expenditure on fuel is required for heating large amounts of flowing gas containing the odiferous components in low concentration; this factor is economically disadvantageous. As one of the measures for resolving this difficulty, a method has been investigated in which only the components with disagreeable odor are adsorbed onto adsorbents from a large amount of flowing gas and after burning the adsorbed component the gas is exhausted without a disagreeable odor. As a gasadsorbing apparatus, those which utilize active carbon as an adsorbent have been envisaged. However, conventional active carbon is unsuitable for the purpose of adsorbing and condensing the basic components having disagreeable odor such as ammonia and amines for reasons arising from the fact that only extremely small amounts of the components are adsorbed thereon. Sulfonated coal (Japanese Patent Publication No.

38-18356 (18356/1963), etc.) and ion exchange resins, etc. have been proposed as deoderants; however, they are unsuitable for use in processes involving heat regeneration because there is a possibility of decomposition due to irreversible chemical changes when they are heated at the temperatures of 100 to 3000C that would be experienced in regeneration processes.

Also, since exhaust gases, containing nitrogen oxides (hereinafter called NOx) such as are exhausted from combustion apparatus have come to be one of the causes of air pollution, several methods have been proposed for removing NON from such gases.

One such method involves the selective reduction of NOx by ammonia. In this previously proposed method, it is necessary to supply an excess of ammonia of several percent because NOX usually does not react with ammonia at a stoichiometrical ratio of 1:1. As a result, some unreacted ammonia will remain in the treated gas. This situation is not only unfavourable economically but also the remaining ammonia may cause secondary air pollution. Conventional adsorbents and deodorants are quit unsatisfactory for removing the remaining ammonia from the gas which was treated and deprived of NON by this ammonia method, because of their poor heat-stability or adsorption efficiency at the higher temperatures involved in the gas treatment.

According to one broad aspect the invention provides a method for removing ammonia and/or at least one amine from a gas containing said ammonia and/or said amine(s), comprising: bringing said gas at a temperature not higher than 2500C into contact with a substance obtained by supporting on a porous and heat-resistant inorganic carrier at least one compound chosen from proton acids and Lewis acids in an amount of 150% by weight based on the weight of said carrier, said proton acids being phosphoric acid, boric acid, a mixture thereof or a condensate thereof, vanadic acid, molybdic acid, chromic acid, an arylsulfonic acid or terephthalic acid and said Lewis acids being nickel sulfate, vanadium sulfate, manganese phosphate or a mixture thereof.

Another broad aspect provides a method for removing ammonia and/or at least one amine from a gas containing said ammonia and/or said amine(s), comprising: (a) bringing said gas at a temperature not higher than 250"C into contact with a substance obtained by supporting on a porous and heat-resistant inorganic carrier at least one compound chosen from proton acids and Lewis acids in an amount of 1 50%, by weight based on the weight of said carrier; (b) thereafter regenerating said substance by heating, at a temperature lower than 10000C but higher than the temperature at which said gas was brought into contact with said substance; and (c) using thus regenerated substance in step (a); said proton acids being phosphoric acid, boric acid, a mixture thereof or a condensate thereof, vanadic acid, molybdic acid, chromic acid, an arylsulfonic acid or terephthalic acid, said Lewis acids being nickel sulfate, vanadium sulfate, manganese phosphate or a mixture thereof.

It will be appreciated that in the practice of the invention, as the process proceeds the acids may react with the ammonia and/or amine(s) to form acid salts; such salts themselves act as adsorhents in the process. In examples described below such salts are used as starting adsorbent material in order to illustrate this phenomenon.

The composite structure of carrier and supported acid(s) will be referred to hereinafter as simply " deodorant ".

In the accompanvine drawings: Fig. 1 is a diagram illustrating one procedure for the removal of ammonia and/or amines from a gas containing the same components utilizing a fluidized-bed type continuous gas adsorbing apparatus; and Fig. 2 is a diagram illustrating another procedure for removing components having disagreeable odor and which are removed from a gas containing the same utilizing a fixed-bed type continuous gas adsorbing apparatus.

The inorganic carrier may be any substance provided it is porous and heatresistant. The shape of the carrier is not critical; however, it is preferably granular. In the cases where the shape of the carrier is granular, the diameter of the granules may be not less than 0.2 mm, and preferably is in the range of 0.2-2.0 mm. For the carrier, for instance, diatomaceous earth, silica gel, titania, zirconia or silica-alumina may be utilized. In addition, granular active carbon may be utilized as the carrier. Spherical granules of active carbon are especially preferred. The spherical active carbon particles can be manufactured using pitch as a starting material as has been disclosed in, for instance, Japanese Patent Publication Nos. 49-25117 (49-25117/1974) and 5018879 (18879-1975). In order to support at least one compound described above onto the carrier, conventional methods may be used. For instance, a predetermined amount of the compound is dissolved into a solvent such as water or ammonia cal aqueous solution, etc. and then a predetermined amount of the carrier is soaked into the solution thus obtained, and after being kept still, the solvent is distilled off from the mixture. The dried residue is heated at a suitable temperature.

It is required that the acid(s) is/are supported on the carrier in an amount of 150% by weight based on the weight of the carrier. If less than 1% by weight is used adsorption efficiency is too low: if the amount is greater than 50% by weight, the acid(s) possibly separate from the carrier. The amount of acid supported on the carrier is determinable as the weight difference between the deodorant and the carrier.

In the practice of the present invention, a gas containing ammonia, and/or amines such as alkylamines, e.g. methylamine and ethylamine, pyridine, is brought into contact with a deodorant as is described above. The temperature (hereinafter called seizing temperature) at which the gas is brought into contact with the deodorant should not be higher than 2500C and preferably not more than 2000C. A fluidized-bed type continuous gas adsorbing apparatus or a fixed-bed type continuous gas adsorbing apparatus may be utilised. Where a fluidized-bed type apparatus is utilised, it is preferred to use spherical carrier particles because of their resistance against attrition and superior fluidising properties.

Although the mechanism of deodorization in the present invention where the gas is brought into contact with the deodorant has not been elucidated, it is presumed that the ammcnia and/or amines are caught and bound by a salt-forming reaction to the above mentioned acids and acid salts.

The expression "adsorption" has been adopted herein as comprehending the mechanism (whatever it may be) by which deodorisation is effected, and the expression should not therefore necessarily be construed as restricted to the relatively narrow con ventional meaning given thereto.

Also the mechanism of the regeneration of the deodorant is presumed to be as follows: that the structure of normal salt or analogous salt, which has been formed by the binding with the odiferous components, is converted by heating to the original structure of acid while releasing the once bound components. The gas deprived of dis agreeable odor may be diffused into the atmosphere. In cases where the gas to be treated contains not only ammonia and/or amines but also other components having a disagreeable odor, the gas may be brought into contact with a mixture of active carbon itself and a deodorant as described above, with the result of simultaneous removal of both components having disagreeable odor.

We describe below deodorants which can be regenerated by conventional heating at a temperature higher than the adsorbing temperature, after use. The temperature of regeneration is not critical but it must be lower than 1000"C; it is preferably not more than 5000C in order to prevent the evaporation or the irreversible change of the acid supported on the carrier. In cases where active carbon is utilised as the carrier, the regenerating temperature is preferably in the range of 10e-300"C. The reason for this is that at a temperature lower than 1000C, it takes too much time for regeneration and at a temperature higher than 300"C, the active carbon is possibly oxidized and consumed by oxygen contained in the air when air is used as the gas for regeneration. Air, nitrogen and mixtures thereof are suitable for regeneration. In addition, steam is preferred for regeneration in cases where active carbon is utilised as the carrier.

When the used deodorant is thus regenerated, the odiferous components are released from the deodorant particles and the release components may be burnt in an after-burner or washed with water in a scrubber, if necessary, after condensation.

As is described above, the preferred deodorants are easily regenerated; the repeated use of the deodorant is possible, and as will be clearly understood by Examples hereinafter, gases containing certain odiferous components are now susceptable to effective treatment with the preferred deodorants of the present invention. Ammonia and/or amines at very low concentrations in large amounts of flowing gas can be effectively removed making the preferred embodiments of the present invention especially suitable for treating gases exhausted from shell-mold factories. In addition, ammonia in exhaust gas resulting from the process of removal of NOi by reduction of NO,- with ammonia can now be effectively recovered by preferred embodiments of the invention.

The invention will now be further described with reference to the following Examples.

Example 1.

Active carbon used as a carrier.

(A) Manufacture of granular carbon particles.

Six kilograms of pitch (softening point of 200"C carbon content of 94% by weight, ratio of H/C of 0.59 and nitrobenzene-insoluble component of 36% by weight) obtained by thermal cracking of Seria crude oil at 2000"C and 1.6 kg of technical grade naphthalene were charged into a 20 1 autoclave provided a paddle-type stirrer and after the gaseous phase within the autoclave was exchanged by nitrogen, the con tent was melt-mixed at 1500C under agitation, and after adding 11 kg of a 0.22 weight per cent aqueous solution of a suspension-agent of incompletely hydrolyzed polyvinyl acetate type (GOSENOL product of Nippon Gosei Co., Ltd.) the mixture was agitated at 260 rpm at 1500C for 30 min to make a dispersion of droplets, then cooling the whole material to a temperature of 30"C for obtaining solidified particles of mix ture of pitch and naphthalene, of average diameter of about 1 mm. The particles were extracted with n-hexane for 5 hours to remove naphthalene from the particles and to obtain porous particles of pitch. The pitch particles were then oxidized by heating in air from 100"C to 3000C at a rate of temperature raising of 10 C/h to obtain infusible pitch particles. By activation of the particles with steam at 8000C for 10 hours, active carbon particles were obtained at a yield of about 40 per cent. The active carbon thus obtained was nearly spherical in shape with high surface hardness and was not easily pulverizable. By sifting these particles, the fraction of 0.7-1.1 mm in diameter was collected to be used in the following experiments (the fraction is called the carrier Q).

(B) Carriers in the experiments.

The granular carbon particles used in the following experiments as the carrier of the deodorants for taking hold of the components having disagreeable odor were Q (manufactured in the process A) and a sifted fraction of 0.7-1.1 mm of crushed coconut-shell coal of commercial origin (hereinafter called the carrier R).

(C) Preparation of deodorants.

In order to attach and support a chemical (mentioned in the following Table 1) onto one of the carbonaceous carriers mentioned above, a predetermined amount of the carbonaceous carrier was soaked into a solution of a predetermined amount of the chemical for 24 hours at room temperature while being kept still. Then, the solution was transferred into a rotary evaporator, the solvent being evaporated. The dried residue was re-dried at 90"C for 24 hours in an atmosphere of nitrogen and then it was heated at about 2000C for 3 hours in nitrogen atmosphere to give a deodorant. Table 1 shows the carbonaceous carrier, the chemical to be carried by the carrier, and the amount of the compound supported on the carrier.

Also for the comnarison with conventional active carbons and deodorants, experiments on the treatment of the gas having disagreeable odor were carried out using the above mentioned carbonaceous carrier itself (that is, not yet supporting the chemical) and a sulfonated coal, respectively. The sulfonated coal was prepared as follows: a bituminous coal (jroduct of Yubari coal mine) of 0.5-2.0 mm in granular size was oxidized with air at 2200C to render it infusible, and then it was treated with sulfuric acid at room temperature to form sulfonated coal. By sifting the sulfonated coal, the fraction with size of 0.7-1.1 mm was obtained (hereinafter called deodorant S) and it was used in the following experiments. The ion exchange capacity of deodorant S was 3.3 milliequivalent/g.

TABLE 1 Recipe for preparation of deodorants for experiments of removing basic components having disagreeable odor from a gas containing the same Amount Deodorant Carrier Chemicals (% by weight) Solvent Q1 Q ammonium tertiary 12 water phosphate Q2 Q dimethylamino tertiary 5 water phosphate Q4 Q ammonium borate 10 water Qs Q ammonium vanadate 8 aqueous ammonia solution Q6 Q ammonium chromate 14 water ffl Q ammonium molybdate 7 aqueous ammonia solution Q8 Q ammonium salt of 15 water benzenesulfonic acid Q9 Q ammonium terephthalate 18 water Qlo Q phosphoric acid 4 water Q11 Q phosphoric acid 8 water Q12 Q phosphoric acid 16 water Q13 Q phosphoric acid 32 water Q14 Q boric acid 8 water QiS Q benzenesulfonic acid 13 water R1 R ammonium tertiary 12 water phosphate Q3 Q ammonium tertiary 0.5 water phosphate (D) Example of procedures for removal of basic components from a gas containing the same.

As a model of gases containing the components to be removed a gaseous mixture was prepared by mixing, with air, 80 ppm of ammonia and 10 ppm of dimethylamine as the odiferous components, and 10 ppm of formaldehyde and 30 ppm of benzene as other components.

A fluidized-bed type continuous gas adsorption apparatus was used for experimental treatment of the gas containing the components, and a Bunsen burner was used for the treatment of a condensed gas exhausted in the cases of regeneration of the used deodorant.

In Fig. 1, the continuous gas adsorbing apparatus was constructed of stainless-steel (SUS 316, Japanese Standard) and was in two sections, one behind the odiferous com ponent removal section 1 in the upper position, and the other being the regenerating section 3 for the used deodorant in the lower position and the two sections being connected by a relatively narrow conduit 2. The regenerated deodorant is transferred through a relatively small diameter air-lift pipe 4 from the bottom of the regenerating section 3 to the top of the adsorbing section 1. The adsorbing section 1 is a cylinder having an inner diameter of 150 mm and is provided with 6 horizontally arranged perforated plates 10 spaced apart vertically by a distance of 100 mm, the perforated plates being of stainless steel of 2 mm in thickness and having number of circular holes of a diameter of 3.5 mm corresponding to an aperture ratio of 17 per cent. The bottom of the adsorbing section 1 forms an inverted cone and is connected to the conduit 2, which is a cylinder of 30 mm in inner diameter and functions as a conduit to transfer the deodorant downwards and while said deoderant acts as a seal preventing the upward escape of the gas mixture containing the odorous components released from the deoderant during regeneration. The regenerating section 3 is a cylinder having an inner diameter of 100 mm, being connected at its top to the conduit 2, and at its bottom forming an inverse cone connected to the air-lift pipe 4. The heat source, superheated steam or nitrogen gas at a high temperature, is directly introduced into the regenerating section 3 through the inlet pipe 8. The air-lift pipe 4 is 10 mm in inner diameter and the transfer of the regenerated deodorant through the pipe 4 is carried out by compressed air supplied from the air compressor 11.

Experiments of deodorization of the mimic gas prepared artificially as described above were carried out in the fluidized-bed type continuous gas adsorbing apparatus described above, using a Bunsen burner 5 attached to the apparatus for burning the components, as follows: After charging one of the deodorants prepared by the process described in (C) into the fluidized-bed type continuous gas adsorbing apparatus, the gas to be treated was introduced into the adsorbing section 1 from the inlet pipe 6 at the lower position of the section 1 at a linear velocity of 90 cm/sec to fluidize the deodorant particles on the perforated plates 10.

The introduced gas containing ammonia and/or amines was deodorized while passing through the fluidized deodorants on 6 perforated plates 10 and then exhausted from the outlet pipe 7 at the top of the section 1. On the other hand, the deodorant flowed downwards at first from the uppermost perforated plate while being brought into contact on each perforated plate with the upward flow of the gas, and after reaching the bottom portion of the section 1 the deodorant flowed down to the regenerating section 3 via the duct 2. The regenerating section 3 was completely packed with the deodorant particles taking the form of fluidized-bed and the deodorant in the section 3 flowed down with a controlled residence time of about 80 min within the section 3. In section 3 the deodorant with the odiferous components adsorbed thereon was heated to a temperature of about 200"C by superheated steam containing a small amount of nitrogen, and the deodorant was regenerated during its flow-down as a fluidized bed in the regenerating section 3. The regenerated deodorant was thereafter transferred to the top of the adsorbing section 1 again via the air-lift pipe 4 in order again to adsorb ammonia and/or amines in section 1. The condensed gas with released odiferous components was released in the section 3 was exhausted through the outlet pipe 9 at the upper section of the section 3 and the gas was burned by the Bunsen burner 5, then exhausted as an odorless gas. The thickness of the fluidized-bed on each of the perforated plates 10 in the adsorbing section 1 was maintained at about 10--20 mm.

After operating the apparatus for 60 hours of recycled adsorption and regeneration, the treated gas was sampled at the exhaust pipe 7 at the top of the adsorbing section 1, and the content of remaining components having disagreeable odor was determined, the results being shown in the following Table 2.

TABLE 2 Residual concentration of components having disagreeable odor in the gas treated by deodorants ( at 60 hours of continuous operation) No. of No. of Ammonia Dimethylamine Formaldehyde Benzene Experiment deodorant (ppm) (ppm) (ppm) (ppm) Remarks 1 Q1 < 1 < 1 2 7 2 Q2 5 1 2 6 3 Q4 < 1 < 1 3 8 4 Q5 3 < 1 4 11 5 Q6 2 < 1 3 9 6 Q7 5 < 1 2 7 7 Q8 < 1 < 1 5 12 8 Q9 4 1 4 7 9 Q10 2 1 1 2 10 Q11 < 1 < 1 2 7 11 Q12 < 0.5 < 1 2 10 12 Q13 < 0.1 < 1 3 14 13 Q14 < 1 < 1 3 8 14 Q15 4 < 1 5 12 15 R1 2 < 1 6 16 considerable pulverization of the deodorant occurred 16 Q1/Q* < 1 < 1 < 1 < 1 Comparable experiments with deodorants other than the present invention 1 Q 76 9 < 1 < 1 2 Q3 43 2 1 < 1 3 S - - - - operation was stopped due to pulverization and deterioration of the deodorant Note: The concentration of ammonia, dimethylamine, formaldehyde and benzene of the artificially prepared gas before treatment was 80, 10, 10 and 30 ppm (volume by volume), respectively.

* The mixture of Q1 and Q (Q1 : Q = 1 1 (volume by volume)) As seen from Table 2, the active carbonaceous carrier itself was effective in removing the components having disagreeable odor except for basic components, but almost ineffective in removing basic components having disagreeable odor.

It was found that the active carbon supporting the chemical(s), which was used in, or as illustrative of the present invention, had an extremely high activity in removing basic components having disagreeable odor from the gas containing the same. Also it was found that the mixture of the active carbon supporting the chemicals and the carbonaceous carrier (refer to Experiment 10) could effectively remove both amine and/or ammonia components and other components which had a disagreeable odor.

On the other hand, the run using a sulfonated coal as a deodorant was obliged to be stopped after a continuous run of 12 hours owing to the severe pulverization of the particles and the rapid reduction of its adsorbing activity due to an irreversible change resulting from regeneration at high temperature.

Example 2.

A case where an inorganic material other than active carbon was used as a carrier.

(A) Carriers used (Carriers K, S, T and L described as follows) Diatomaceous earth carrier was prepared by pelletizing diatomaceous earth powder (product of Makari) into cylindrical shape having a diameter of about 2 mm, sintering the pellets at about 10000C, and crushing and sifting to collect the crushed fraction of granules of 10-30 mesh (by the Tyler standard). The thus obtained carrier was called Carrier K.

Silica gel carrier was prepared by crushing a commercial granular silica gel (commercial one by Junsei Kagaku Co., Ltd.) and sifting the crushed particles to collect the fraction of granules of 10--30 mesh (by the Tyler standard). The thus obtained carrier was called Carrier S.

Titania gel carrier was obtained, at first by slowly adding a 50% aqueous ammonia solution into a mixed aqueous solution of titanium sulfate and aluminum sulfate (weight ratio of the two salts = 90:10) to obtain a gel, then slowly drying the gel and heat-treating the gel at 5000 C, and secondly by sifting the obtained granular substance to collect the fraction of 1030 mesh (by the Tyler standard). The carrier was called Carrier T.

Silica-Alumina carrier was obtained by crushing the commercial cylindrical pellets of silica-alumina (made by Nikki Chem. Co., Ltd.) and sifting the crushed pellets to collect the fraction of 10-30 mesh (by the Tyler standard). The carrier was called Carrier L.

(B) Preparation of deodorants In order to deposit the specified chemical on the carrier, a predetermined amount of the carrier was charged into a glass column of fluidized-bed and 2tn aqueous ammoniacal solution containing a specified amount of an ammonium salt (normal salt) was sprayed from the top of the column onto the carrier while dry air (at 50"C) was introduced from the bottom of the column in order to fluidize the carrier and at the same time to dry the sprayed solution on the carrier. The carrier applied with the salt was heated for 2 hours at 250"C; the salt changed to an acidic salt. This carrier was used, in experiments, to process a flue gas treated with ammonia for reducing NOx.

In order to obtain the carrier coated with condensates, the above-mentioned carrier applied with an acidic salt was heated for one night at 3000 C, the acidic salt being changed to its condensate. Table 3 below shows the kinds of carriers, the substance supported on the carrier and the amounts of the substances supported on the carrier.

TABLE 3 Recipe for preparation of deodorants Sign of Substance supported deodorant Carrier on the carrier k by weight Kl K condensate of ammonium phosphate K2 K condensates of ammonium phosphate and ammonium borate Si S ammonium nickel sulfate and ammonium phosphate T1 T ammonium vanadium sulfate L1 L ammonium manganese phosphate and ammonium phosphate K6 K condensate of phosphoric acid K3 K condensate of ammonium phosphate *K4 K condensate of phosphoric acid *K5 K ammonium manganese phosphate and ammonium phosphate

Notes: * comparative examples.

(C) Examples of procedures for removal of ammonia and/or amines from a flue gas treated with ammonia in order to reduce NOX.

First, an exhaust gas from a boiler, containing 150 ppm of NOX, was passed through a catalyst of iron oxides under a supply of ammonia at 225 ppm of the gaseous mixture at 3500C and at a space velocity of 7000 h~1 in order to reduce the NOX with ammonia. The resulting gas containing residual ammonia in an amount of about 85 ppm was treated to remove residual ammonia at high temperature using the deodorants which were prepared as described in (B).

The apparatus used for the experiments was a fixed-bed type continuous gas adsorbing apparatus shown in Fig. 2. In addition, a part of the gas deprived of NOx was cooled by a heat-exchanger to 100--2000C for removing the remaining ammonia, and the recovered ammonia was utilized again for removing NOX of more exhaust gas of the kind originally described. The apparatus shown in Fig. 2 was made of a stainless steel (SUS 316, Japanese Standard) and was composed of two similar towers (1 and 1'), 1000 mm in height and 150 mm in inner diameter. A perforated dish (3 and 3') having holes 0.2 mm in diameter and aperture ratio of 20% was set in each tower at the position 300 mm from the bottom, on which one of the deodorants prepared as described in (B) was mounted with its thickness of 200 mm for adsorbing ammonia. When one tower (1 or 1') was in operation, treating the NOx, depleted ex haust gas a regeneration process was conducted in the other tower and the both pro cesses were interchanged eve residual ammonia, then exhausted into the atmosphere from the outlet pipe 5. At the same time, nitrogen gas at a high temperature (moisture content of 5%) was intro duced into the tower 1' from the regenerating gas inlet 6, and was passed through the deodorant layer 2' at a space velocity of 100 h-1 to heat the deodorant to the tempera ture of regeneration then the absorbed ammonia on the deodorant was released. The gas containing released ammonia (ammonia content of approximately 6.5 vol. /O) was exhausted from the outlet of condensed gas 7 and was returned to the apparatus for removing NOX (not shown) by the blower 8.

The operation described above was continued by switching each tower 1 and 1' every 3 hours, using every deodorant as well as carriers K and L themselves and, at 24 hours from the beginning of operation, the treated gas was sampled from the outlet pipe 5 and its ammonia content was determined. The results are summarized in Table 4 below.

TABLE 4 Concentration of residual ammonia in the gas after treatment, with deodorants, of the gas treated with ammonia to reduce Nox' content (after 24 hours of continuous operation) Temperature Temperature Concentration No. of No. of of adsorption of regeneration of residual Experiment Deodorant ( C) ( C) ammonia** 1 K1 130 310 1 2 Kl 125 270 3 3 K2 150 320 4 4 S1 120 280 4 5 T, 105 270 6 6 L1 120 270 3 7 K3 120 300 4 8 K6 130 310 1 *Com. -1 K4 130 300 44 *Com. -2 K5 130 300 51 *Com. -3 K 130 300 82 *Com. -4 L 130 300 83 Notes: * Comparable experiment with deodorants other than the present invention.

** ppm (volume by volume).

As will be apparent from Table 4 above, the deodorants used in the present inven tion can effectively collect ammonia in a high temperature exceeding 1000 C. In con trast, the deodorants of from com. -1 to com. -2, in which the amount of substance supported on the carrier is naught or extremely small, can not collect ammonia sufficiently.

Claims (8)

WHAT WE CLAIM IS:

1. A method for removing ammonia and/or at least one amine from a gas containing said ammonia and/or said amine(s), comprising: bringing said gas at a temperature not higher than 250"C into contact with a substance obtained by supporting on a porous and heat-resistant inorganic carrier at least one compound chosen from proton acids and Lewis acids in an amount of 1--50 by weight based on the weight of said carrier, said proton acids being phosphoric acid, boric acid, a mixture thereof or a condensate thereof, vanadic acid, molybdic acid, chromic acid, an arylsulfonic acid or terephthalic acid and said Lewis acids being nickel sulfate, vanadium sulfate, manganese phosphate or a mixture thereof.

2. The method according to Claim 1, wherein said arylsulfonic acid is benzenesulfonic acid.

3. The method according to Claim 1 or 2, wherein said amine is methylamine, ethylamine or pyridine.

4. A method for removing ammonia and/or at least one amine from a gas containing said ammonia and/or said amine(s), comprising: (a) bringing said gas at a temperature not higher than 250"C into contact with a substance obtained by supporting on a porous and heat-resistant inorganic carrier at least one compound chosen from proton acids and Lewis acids in an amount of 150% by weight based on the weight of said carrier; (b) thereafter regenerating said substance by heating, at temperature lower than 1000"C but higher than the temperature at which said gas was brought into contact with said substance; and (c) using thus regenerated substance in step (a); said proton acids being phosphoric acid, boric acid, a mixture thereof or a condensate thereof, vanadic acid, molybdic acid, chromic acid, an arylsulfonic acid or terephthalic acid, said Lewis acids being nickel sulfate, vanadium sulfate, manganese phosphate or a mixture thereof.

5. The method according to Claim 4, wherein the regeneration temperature does not exceed 5000 C.

6. The method according to Claim 4 or 5, wherein said arylsulfonic acid is benzenesulfonic acid.

7. The method according to any one of Claims 4 to 6, wherein said amine(s) is or are chosen from methylamine, ethylamine or pyridine.

8. A method for the removal of basic components of disagreeable odor from a gas according to Claim 1 or Claim 4, substantially as herein described with reference to the accompanying drawings.