Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
  • B01D17/02—Separation of non-miscible liquids
  • B01D17/0202—Separation of non-miscible liquids by ab- or adsorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/28—Treatment of water, waste water, or sewage by sorption
  • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents

Definitions

• the present invention relates to a method for reducing the hydrocarbon content in air or water.
• organic substances especially hydrocarbons, that have proved to be injurious to nature and human beings are various solvents used in paint-spraying and printing processes, chlorinated hydrocarbons from cleaning processes, chlorinated compounds obtained as by-products in various production processes, by-products in various combustion processes and production processes etc.
• the technique which has been utilised most widely so far is based on adsorption with activated carbon as adsorbent, air or water being caused to pass through a filter' comprising the activated carbon which may be present in the form of a bed or have been applied to a carrier, such as paper or a ceramic material.
• the activated carbon may also be present in the form of a fluidised bed, in which case the air or the water to be treated constitutes the fluidising agent.
• the activated carbon has been used for a long time, and its advantages in the purification of air and water are well known. In spite of the fact that these known methods have been developed in the course of time towards increasingly better methods, they still suffer from certain disadvantages that could net be surmounted. Thus, the activated carbon has a low efficiency at low impurity concentrations. Furthermore, it is combustible and does not bear high temperatures, for which reason its regenerability is very limited after adsorption of high-boiling molecules. Furthermore, it is a "dirty" material, the handling of which evokes some aversion.
• the use of different polymers as adsorbents has been discussed for quite some time.
• the properties of the polymers are similar to those of the activated carbon, such as their adsorption capacity and their broad usefulness for a number of different adsorbable types of molecules.
• they also have many of the disadvantages of the activated carbon, such as being combustible and susceptible to temperatures,
• the object of this invention to provide a method of reducing the hydrocarbon content in air or water.
• the method according to the invention is characterised in that the air or the water is caused to pass through a filter comprising a hydrophobic crystalline zeolite.
• the zeolites used in the context of this invention have been made hydrophobic by giving them a high Si:Al ratio, either by direct synthesis or by modification of zeolites having a lower Si:Al ratio.
• a normal zeolite is hydrophilic in character and adsorbs water vapour in preference to organic molecules.
• By direct synthesis or by chemical modification of existing zeolites it is possible to obtain zeolites which are hydrophobic or lipophilic so that their tendency to adsorb organic molecules is increased. Because of their crystalline structures, these zeolites are capable of selectively adsorbing such substances as phenols, guaiacols, various solvents, degreasing agents, products from biochemical processes etc. from air or water, the dimensions of the crystalline structures determining the selective properties, primarily in respect of the size of the adsorbed molecules.
• the zeolites used in the context of this invention are crystalline materials consisting of silicon, aluminium and oxygen and, optionally, simple cations, such as sodium or hydrogen ions. They are not combustible and bear heating to 800-900°C, which means that they can be subjected to regeneration processes under inclement conditions. Furthermore, the hydrophobic zeolites can be treated with mineral acids and thereby be freed from particle coatings.
• the crystal structures are selective in respect of the molecules that can be adsorbed. In other words, they function as inverted sieves, i.e. they adsorb molecules up to a given size which is determined by the crystalline structure concerned, whereas the larger molecules are allowed to pass.
• the zeolites may be hydrophobated gradually from the state in which they have entirely hydrophilic characteristics until they become entirely hydrophobic, which means that the hydrophobicity can be set to a value suitable for the type of molecules to be adsorbed.
• Zeolites suitable for hydrophobation in this invention are heulandite, mordenite, phillipsite, chabazite, natrolite, analcite, clinoptilolite, gmelinite and/or faujasite.
• the zeolites which so far have proved to be efficient are those having a ratio of Si:Al which is higher than 15:1, in particular HAISi 35 O 72 and HAlSi 25 O 52 .
• the present invention is applicable to different uses, such as to the removal of relatively low contents of toxic substances, especially organic substances, from water. Furthermore, it may be used for removing toxic substances, especially such as are formed upon the combustion of fuels, from air introduced into motor vehicles, ships or buildings. Finally, the method can be used also for reducing the content of toxic substances in air discharged over densely populated areas.
• the filters can be installed in different ways in inlet and outlet ducts. For example, a number of filter cartridges can be mounted in a collective housing for purifying contaminated water. When the filters have become more or less saturated with impurities, they are regenerated by admission of hot air or inert gas. After this regeneration, the solvents can then be recovered by condensation.
• Butanol was prepared by a continuous chemical fermentation process. When the butanol content had reached 2.8%, the process stopped because the alcohol content became too high for the microorganism. By allowing the process water to pass through a hydrophobic zeolite having the composition HAISi 35 O 72 , the alcohol content was reduced and could be maintained at a constant level of 0.2%. The butanol was adsorbed continuously by the zeolite, and the process solution therefore did not reach the butanol concentrations toxic to the microorganisms. When the zeolite was saturated with butanol, it was replaced by a new batch of zeolite, and the butanol was recovered from the saturated zeolite. EXAMPLE 2
• Waste water from the alkaline bleaching of papermaking pulp with low contents of chlorophenols and chloroguaiacols and high contents of methanol and formic acid was treated after pH adjustment with hydrophobic zeolite having the composition HAlSi 35 O 72 .
• the content of chlorophenols and chloroguaiacols was reduced by about 35%, which content refers to the proportion of such compounds having kinetic diameters of less than about 8A.
• Waste water from the chlorine bleaching of papermaking pulp with low contents of chlorophenols and chloroguaiacols and high contents of formic acid and methanol was treated directly with hydrophobic zeolite having the composition HAlSi 35 O 72 .
• the content of solvents was reduced by about 30%, which content refers to the proportion of such compounds having kinetic diameters, of less than about 8A.
• Exhaust air from a spray-painting booth containing 200 mg solvent per m 3 , primarily xylene and white spirit, was treated with a hydrophobic zeolite having the composition HAlSi 35 O 72 . The solvent content was reduced to 1 mg per m of air. The adsorbed amount of solvent was then distilled off and recovered from the zeolite.
• Example 6 Exhaust air containing 2800 mg solvent per m 3 of air from a spray-painting booth was treated with a hydrophobic zeolite having the composition HAISi 35 O 72 . The solvent content in the treated air was decreased to about 1.5 mg per m 3 . The adsorbed amount was distilled off and recovered from the zeolite.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• Inorganic Chemistry (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Thermal Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Treating Waste Gases (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Gas Separation By Absorption (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1984
  • 1984-05-03 SE SE8402393A patent/SE8402393D0/sv unknown
  • 1984-06-07 EP EP19840902471 patent/EP0144416A1/en not_active Ceased
  • 1984-06-07 WO PCT/SE1984/000216 patent/WO1984004913A1/en active IP Right Grant
• 1985
  • 1985-02-07 DK DK56485A patent/DK56485D0/da not_active Application Discontinuation
  • 1985-02-08 FI FI850529A patent/FI82611C/sv not_active IP Right Cessation

Non-Patent Citations (1)

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