WO1995015215A1

WO1995015215A1 - Composite catalyst for removing mercaptans from liquids and gasses

Info

Publication number: WO1995015215A1
Application number: PCT/US1994/013933
Authority: WO
Inventors: Sergey G. Kuz'min; Sevtlana Borisenkova; Yuriy M. Golub; Azat F. Vil'danov; Oleg L. Kaliya; Akhmed M. Mazgarov; Evgeniy A. Luk'yanetz; Valentina M. Derkacheva; Vyacheslav A. Fomin
Original assignee: International Technology Exchange Corporation
Priority date: 1993-12-03
Filing date: 1994-12-01
Publication date: 1995-06-08
Also published as: AU1431095A

Abstract

A novel metal phthalocyanine derivative heterogeneous composite catalyst comprising a metal phthalocyanine complex and a bifunctional substrate which, with the phthalocyanine, forms the compositecatalyst. The bifunctional substrate provides a surface for the adsorption of the metal phthalocyanine complex, and possesses the properties of a moderate base, or has been modified in a way which imparts to the substrate the properties of a moderate base. Also disclosed is a method for oxidation of thiols and sulphides to inorganic thiosulphates or sulphates and mercaptans to organic disulphides in gaseous, oily or aqueous liquid wastes by means of the action of the metal phthalocyanine derivative heterogeneous composite catalyst.

Description

COMPOSITE CATALYST FOR REMOVING MERCAPTANS FROM LIQUIDS AND GASSES

BACKGROUND OF THE INVENTION Field of the Invention

The present invention is concerned with a novel metal phthalocyanine derivative heterogeneous composite catalyst, and to the oxidation of thiols and sulphides to inorganic thiosulphates or sulphates and mercaptans to organic disulphides in gaseous, oily or aqueous liquid wastes by means of the catalytic action of the metal phthalocyanine derivative heterogeneous composite catalyst. The heterogeneous catalyst can be used to advantage in cellulose- paper, petro-chemical and other chemical industries, and in deodorizing biogasses produced by decomposition or combustion engineering. Description of Related Art

Mercaptans and other sulfur containing compounds are characterized by an offensive odor, toxicity, and corrosive effect on metals, and it is desirable to eliminate these compounds or to convert them to less harmful forms.

It is known to cleanse exhaust gases containing undesirable ingredients by passing them through an adsorbent layer, such as silica gel, zeolites, or activated carbon fibers. See Japanese Published Application No. 57-174120 (1982). However, such methods are considered to be impractical due to their low level of cleaning of gases which is a result of the low effectiveness of simply relying on the adsorption of undesirable ingredients onto the adsorbent, especially when there is a high flow or volume of exhaust gases.

Also known are methods of cleansing vent-emissions and air by oxidizing low-molecular mercaptans contained therein with ambient oxygen as an oxygenating agent in the presence of a heterogeneous catalyst comprising a solid carrier, such as activated coal, saturated with an alkali (see French Patent Application No. 23083899 (1976) and UK Application No. 1501571 (1978). Although these materials can function as low-activity catalysts, the methods of cleansing using them are noted for their low level of cleaning of mercaptans from exhaust emissions. Another known method of "deodorizing" industrial gas emissions or air involves a heterogeneous catalyst composite comprising an organic or inorganic base and cobalt or iron phthalocyanine deposited on a solid carrier. See Japanese Patent No. 62-290462 (1987). In this catalyst, the organic or inorganic base may be an alcohol, a compound of phosphorus, sulfur, or amine, or organic and inorganic metallic salts; and the solid carrier may be, e.g., cotton, wood, viscose, cellulose, sawdust, leather, activated coal, silica gel, alumosilicate, alumina, cement, and polymer materials.

In this method, the high catalytic activity of the cobalt phthalocyanine or iron phthalocyanine result in a high level of cleaning of mercaptans from gases and air (~ 99.5%). However, the shortcoming of such composite catalysts is the lessening of the level of removal of mercaptans from gases or air when the catalytic composite is used for a longer period of time, such as 15 hours or more. This loss of catalytic activity is attributed to the gradual conversion of the organic or inorganic base into a less active compound, which is due to the presence of carbon dioxide in gases and air which reacts with and neutralizes these bases.

It is known from U.S. Patent 3,029,201 to treat water with cobalt phthalocyanine in an alkaline solvent as an oxidation catalyst to convert sulfur impurities, such as hydrogen sulfide, ammonium sulfide, sodium sulfide, potassium sulfide, aliphatic mercaptans, and thiophenols, to a form having lower biological oxygen demand. Activated carbon such as charcoal is used as a preferred carrier, and air is the preferred oxidizing agent. An alkaline solvent is required, and in the Examples, reactions are carried out for only 13-15 minutes.

Due to the economic importance of petroleum, heavy research has been conducted into the oxidation of malodorous mercaptans contained in "sour" hydrocarbon distillates. Mercaptan oxidation chemistry is very similar to the chemistry of oxidation of inorganic sulfides to elemental sulfur, and petroleum sweetening catalysts can be directly applied to processes for oxidizing inorganic sulfides to elemental sulfur in aqueous environments.

U.S. Patent 3,108,081 concerns treatment of hydrocarbon distillates. The mobile phase hydrocarbon distillate and an alkaline reagent solution are contacted with a fixed bed composite comprising a phthalocyanine catalyst and a solid carrier which is insoluble or substantially unaffected by the caustic solution in the treatment zone. Exemplary carriers include carbon (e.g., coke, charcoal obtained from bone char, wood charcoal, charcoal made from coconut or other nut shells or fruit pits), silica, clays, silicates, aluminas, ceramics, various magnesium compounds, titanium compounds, and zirconium compounds. In the Examples, the alkaline agent is charged continuously or intermittently as required to maintain the catalyst in a caustic wetted state, and in this manner runs using 1% cobalt phthalocyanine sulfonate on activated carbon are continued for 63 hours.

U.S. Patent 3,230,180 teaches increasing the concentration of phthalocyanine on the carrier by forming the phthalocyanine in the presence of the carrier and heat. U.S. Patent 3,565,959 indicates that prior catalysts have been unsatisfactory with respect to catalyst life and catalytic activities, and that superior activities and life can be obtained using a poly metalo- phthalocyanine such as poly cobalt-phthalocyanine. Oxidation of mercaptans must be carried out in an aqueous alkaline solution, otherwise the reaction rate is slow.

U.S. Patent 3,686,094 teaches that the oxidation of mercaptans to disulfides may be carried out with oxygen in the presence of a catalyst in the absence of an aqueous alkaline solution by including in the solid catalytic mass an alkali metal oxide or hydroxide.

It is known to use ethanol, ammonia or ammonium hydroxide (U.S. Patent 4,248,694), or an alkanol amine (U.S. Patent 4,956,325) as the solvent for the metal phthalocyanine catalyst when impregnating the solid composite catalyst.

U.S. Patent 5,162,279 teaches improving stability of a metal complex catalyst by immobilizing the metal complex on an inorganic carrier to which a long molecular chain capable of surrounding the metal complex is bound. The long molecular chain surrounds the metal complex and forms a cavity for surrounding the reaction substrate.

It is also known to carry out the oxidation reaction using an organic base such as tetraalkyl guanidine as disclosed in U.S. Patent 4,207,173 or a quaternary ammonium hydroxide as disclosed in U.S. Patent 4,260,479. U.S. Patent 5,204,306 teaches an aqueous solution containing a metal chelate (e.g., cobalt phthalocyanine), ammonium hydroxide and an onium compound for sweetening a sour hydrocarbon fraction or for supplementing the activity of fixed bed catalysts which have a tendency to deactivate over time. However, these organic bases are more expensive than inorganic bases.

The above processes are disadvantageous in that they generally require a strongly basic medium to effect the oxidation reaction. U.S. Patent 4,498,977 teaches that the prior art has always relied upon the presence of alkaline agents to retard the rapid deactivation of metal chelate catalysts during hydrocarbon sweetening, which alkaline agents added expense, requiring post- treatment separation of alkaline reagent from product, and disposal of spent alkaline reagents.

U.S. Patent 4,364,843 teaches that the activity stability of a composite catalyst comprising a metal chelate (e.g., cobalt phthalocyanine, cobalt phthalocyanine mono- or disulfonate) and a support can be improved by preparing the composite from an admixture of an alcohol, an alkali metal hydroxide, a metal chelate, and an adsorptive support (e.g., activated charcoal). It is disclosed that, while it has heretofore been the practice to oxidize mercaptans in petroleum distillate in the presence of an alkaline agent, many distillates can be treated in the absence of an alkaline agent when using this composite catalyst.

U.S. Patent 4,672,047 teaches that no method is known that does not require the use of base in addition to the metal chelate catalyst, and teaches a catalyst for oxidizing mercaptans to disulfides, which catalyst is indicated to be an improvement over existing catalysts in that it does not require basic agents such as caustic. The catalytic agent is a compound consisting of a metal atom, the metal atom being selected from a specified group not containing cobalt, bonded to a chelate, such as a phthalocyanine, and also to axial ligands. The catalyst is supported on an inert carrier having a high surface area. The use of this particular catalyst is said to overcome prior art problems which accompany the use of basic agents, such as formation of soaps which plug the catalyst bed, the contamination of the final distillate product with either sodium hydroxide or water, formation of sodium salt emulsions that carry water into the final product, and the cost of replacing and disposing of the caustic solution. As a patent which has addressed the problem of the removal of nitrogen oxides, carbon monoxide, and residual hydrocarbons from exhaust gases, reference may be made to U.S. Patent 4,970,188. This patent teaches the prevention of entrainment or blowing out of the active component, such as a metal phthalocyanine, in the case of strong gas currents, by virtue of an inventive intimate mixing or combining of catalyst and carrier. More specifically, where the prior art directly dissolved the metal phthalocyanine per se in a solvent to form a solution or suspension and then impregnated the carrier with the solution or suspension, the metal phthalocyanines are here first rendered soluble by conversion into soluble derivatives such as by adding side groups, and the carriers are then impregnated with a solution containing the solubilized phthalocyanines. Upon stripping the solvent, side groups causing the solubility are split off thermally or by oxidation, and the metal phthalocyanines convert back into active catalyst. This patent, however, does not address the chemistry of removal of malodorous sulfur containing molecules such as sulfides and mercaptans, and does not mention the use of alkaline conditions.

There remains a need for improvements in catalytic activity and long term stability for treating vent gases and liquids containing low molecular weight mercaptans and sulfides.

The object of the present invention is to increase the operational speed and volume of the passage of vent emissions through a catalyst, and the preservation for a prolonged duration of a high level of cleaning of mercaptans from the vent emissions, while avoiding problems associated with the use of an alkaline material such as gradual loss of activity, expense, need for replenishment, formation of soaps, and contamination of down-stream products. SUMMARY OF THE INVENTION

These objects of the invention are accomplished by means of a novel heterogeneous composite catalyst comprising a metal phthalocyanine derivative deposited on a bifunctional substrate which, with the phthalocyanine, forms a composite catalyst. The substrate may be comprised mainly of any of those substances which are known to be useful as carriers, so long as at least the substrate possesses moderate basicity or has been modified to exhibit the properties of a moderate base. In a preferred embodiment, the substrate is a carbon fiber material, preferably in the form of felt, with the active phase catalyst being deposited on the activated carbon fiber in amounts of from 0.001 to 2.5% by weight based on the weight of the substrate. This composite catalyst is then used to cleanse vent- emissions or liquids of mercaptans by passing the fluid phase through the static composite catalyst. DETAILED DESCRIPTION OF THE INVENTION

The present invention is founded in large part on the discovery that the active life of a phthalocyanine catalyst can be extended by selecting and/or modifying the substrate to have the characteristics set forth below. In the present invention, the substrate is one which, with the phthalocyanine, forms a composite catalyst, and may be any of a class of substances which is characterized by a moderate basicity (as opposed to acidity). The term "moderate basicity" as used herein is intended to mean the basicity necessary to render the phthalocyanine catalytically active, and is well understood by those working in the art.

Unlike the prior art patents described above, wherein base compounds are used as a reagent together with phthalocyanine in the oxidation process, the substrate of the present invention has a role which is bi-functional by nature as it serves first as a carrier for adsorption of the active phase (i.e., the metal phthalocyanine) and secondly acts as the permanent moderate base medium for the catalytic process. a. Metal Phthalocyanine

As the metal phthalocyanine or metal phthalocyanine derivative (hereafter collectively referred to as metal phthalocyanines), practically all metal phthalocyanine catalysts can be used, particularly those which can (1) promote the oxidation of sulfur containing compounds (e.g., biogasses and products of biodegradation) and (2) be dissolved or made soluble in a solvent. As the solvent, any solvent can be used, but water is particularly preferred in view of environmental safety and low cost.

The phthalocyanines which can be used in this invention include those disclosed in the above mentioned patents, and particularly U.S. Patent 4,290,913, the texts of which are incorporated herein by reference. Although cobalt phthalocyanines are particularly preferred as oxidants for mercaptans, other metals, such as iron, may be used, and to a lesser extent nickel, chromium, manganese, zinc, vanadium, titanium, molybdenum, and other metals may be used.

As used herein, the term "derivative of phthalocyanine" means a phthalocyanine which contains a substituent. Examples of particularly preferred phthalocyanine derivatives include:

(a) cobalt disulphophthalochanine (CoDSPc), which is cobalt phthalocyanine (CoPc) containing two S0₃H groups as substituents in the macrocycle;

(b) cobalt bis-N-(4-hydroxyphenyl)-N-carboxymethyl sulfamoyl phthalocyanine (CoBPCSPc) , which is CoPc which contains as substituents in the macrocycle two S0₂N(CH₂C00H) (4-H0C₆H₄) groups (also commonly referred to as cobalt glycine photo sulfamoyl phthalocyanine) ;

(c) cobalt bis-(N-benzyl-N-carboxymethyl)-sulfamoyl phthalocyanine (CoBBSPc) which contains as substituents in the macrocycle two S0₂N(C₆H₄CH₂) (CH₂C00H) groups (also commonly referred to as cobalt benzyl glycine sulfamoyl phthalocyanine).

In view of the high and sustained activity when used with the specified carrier of the present invention, phthalocyanines can be used in amounts of from 0.001 to 2.5% by weight based on the weight of the substrate, preferably 0.005 to 1.5% by weight, and most preferably 0.01 - 0.70% by weight in the case that the substrate is carbon fiber. These small amounts allow for a reduction in cost of catalyst for a given application, and a low cost for the whole process of removing malodorous sulfur containing compounds from the atmosphere or liquids in general. b. Oxidant

The oxidant for oxidizing mercaptans and other sulfur containing compounds may be molecular oxygen in purified form or in air or in any other oxygen-containing or supplying gas or liquid, such as nitrogen oxide, hydrogen peroxide, or any other peroxide. However, cobalt phthalocyanine derivatives are selected as catalysts for reasons of being active in oxidizing low-molecular mercaptans with atmospheric oxygen, and thus the readily available atmospheric oxygen should be entirely adequate. c. Substrates

Suitable substances which can be used for the substrates of the present invention include zeolites, activated carbon (preferably carbon fibers, and particularly activated carbon fibers), alumina, calcium aluminate, modified silica, polymers [preferably polymer fibers, such as polyurethane fibers, acrylic fibers (e.g., acrylonitrile optionally copolymerized with acrylic acid, methacrylic acid, allylsulfonic acid, salts of these acids, acid chlorides acid amides, N-substituted derivatives of vinyl amide, vinyl chloride, vinylidene chloride, alpha- chloroacetonitrile, vinylpyridines, vinylbenzenesulfonic acid, and alkaline earth metal salts thereof)], and any other supports, so long as they have a sufficiently well developed surface area for adsorbing metal phthalocyanines, possess the physical characteristics desired for the environment of use, and act as a moderate base to provide a permanent moderate base medium for the catalytic process. That is, conventionally used materials such as activated carbon or zeolite which are not normally characterized by basicity, but which can be chemically modified by well known processes to be provided with basic centers, can be used in the present invention. Regarding activated carbon, it is possible to either include precursor materials in the raw materials which provide basic centers upon the carbonization or activation of the carbon, or to treat the carbon or activated carbon prior to deposition of the phthalocyanine.

As basic centers, any chemical functional groups may be used which are permanently attached to the carrier substrate and which impart basic (or alkaline; as opposed to acidic) characteristics to the substrate. These functional groups include nitrogen containing groups (amino groups, a ido groups, pyridines, pyrimidines, piperidines) , sulfonic acid groups, hydroxyl groups, carboxyl groups, and halogen atoms, and any of the well known organic or inorganic groups which have basic properties. Preferred among these are the amino groups. Representative examples of carbon fiber substrates which can be used in the present invention include the following:

(a) acrylic fiber, e.g., acrylonitrile optionally copolymerized with acrylic acid, methacrylic acid, allylsulfonic acid, salts of these acids, acid chlorides acid amides, N- substituted derivatives of vinyl amide, vinyl chloride, vinylidene chloride, alpha-chloroacetonitrile, vinylpyridines, vinylbenzenesulfonic acid, and alkaline earth metal salts thereof; and

(b) rayon.

As a fibrous precursor material for the carbon fibers which can be used in accordance with the present invention, the materials are not particularly limited, and a representative list includes the following:

(a) a pitch based fiber (petroleum or coal derived);

(b) phenolic resin;

(c) acrylic fiber;

(d) rayon; and

(e) natural cellulosic fiber (e.g., cotton fiber).

The carbon fiber is preferably in the form of carbon felt, and is preferably in the group of activated carbon materials that are characterized by a high surface area, preferably 100-3000 m²/g_. ^as well as a flexible structure. The term "felt" as used herein is intended to mean strands preferably having a length to diameter ratio of 10:1 or greater, preferably 10:1 to 100:1.

Examples of patents teaching methods of manufacture of activated carbon fiber felt include USP 4,412,937 (Ikegami et al), USP 4,520,623 (Ogawa et al), and USP 5,230,960 (Iizuka), and patents referenced therein, the disclosures of which are incorporated herein by reference.

A preferred carbon fiber for use in the present invention is a carbon fiber with the tradename ANM-B produced by Scientific Production Associated, Neorganica, Electrostall region, Moscow, Russian Federation. The technical specifications of this fiber are set forth in "Technical Condition T=F5 6-16-28-1497-92".

A further specific example of a composite catalyst according to the present invention is made by depositing a cobalt phthalocyanine derivative as the active phase of the composite catalyst on calcium aluminate as the substrate. This composite may be used for removing low-molecular mercaptans from vent-emissions. Owing to the heterogeneous catalyst which contains cobalt phthalocyanine with a high catalytic activity, a high level of cleaning of mercaptans from vent-emissions occurs (~ 99.8%). Using calcium aluminate, which possesses a fixed base, as the support in the catalyst composite also guarantees a high level of cleaning throughout a prolonged duration of catalyst usage. Details of the method of production and method of use are set forth in Russian Certificate of Authorship No. 1801559, Application No. 4913238/26, published March 13, 1993, to the present inventors. However, this method has shortcomings. For example, the catalyst composite has a large dynamic resistance, rendering it unsuitable for treatment of a fluid phase having a high flow rate. Further, the composite inherently has a lowered level of cleaning of vent- emissions of mercaptans when the flow rate of the emissions past the catalyst is speeded up. Even an increase in the concentration of heterogeneous catalyst has not allowed for improvement in activity of increased passage during cleaning of mercaptans from vent-emissions and, therefore, there has not been possible an increase in effectiveness.

Accordingly, it is preferred to use a substrate which has a sufficiently well developed surface area for adsorbing metal phthalocyanines, possess the physical characteristics desired for the environment of use, and has functional groups to provide a permanent moderate base medium for the catalytic process, and preferred among these is an activated carbon fiber of a type having basic centers.

The precise reason for the remarkable improvement in prolonged activity due to the combined use of the metal phthalocyanine and activated carbon fiber according to the present invention may be that carbon fiber is closer to graphite in structure than charcoal (amorphous carbon) is, and thus may provide for a more efficient distribution of phthalocyanine molecules along the composite catalyst surface. When using phthalocyanine as a process catalyst in a heterogeneous catalyst system, the choice of a carrier is very important since it is necessary to fix discrete phthalocyanine molecules over the carrier surface without losing the catalytic activity and to avoid aggregation of phthalocyanine molecules. Aggregation is a major problem in the prior art. In the case of aggregation only one of the molecules in the aggregate will work as a catalyst.

Further, it may be that activated carbon fiber can be provided with a high number of basic centers and thus, during the process of oxidizing mercaptans, satisfactorily executes the functions of a moderate base and provides for a higher efficiency of catalytic oxidation. The carbon fiber thus acts both as a carrier and as a moderate base wherein the base is not "spent" as in the prior art.

The selection of a bi-functional substrate which acts as both a carrier and as a moderate base in accordance with the present invention is a novel and characteristic feature of the present invention. By comparison, it is known, for example, from U.S. Patent 5,162,279, to immobilize a metal chelate on a substrate which has "reactive groups" such as hyroxyl, carboxyl, halogen, amino, sulfonic acid, etc. This patent teaches improving stability of a metal complex catalyst by immobilizing the metal complex on an inorganic carrier (a modified silica) to which a long molecular chain capable of surrounding the metal complex is bound. The long molecular chain surrounds the metal complex and forms a cavity, which cavity provides the reaction sites in the place of the fine pores which form the reaction sites in conventional inorganic substrate. In accordance with this patent, the reactive groups are used to bond the long molecular chain molecules, and to covalently bond metal complexes or short chain molecules provided with metal ion capturing groups (such as carboxyl groups, thiocarboxyl groups, amino group, azo group, cyano group, hydrophosphorous acid group, phosphorous acid group, imine group, alkylphosphine group, arylphosphine group, selenol group, etc.). It is apparent that, upon reaction of this carrier with the long chain molecules and short chain molecules, the reactive groups of the carrier will be masked, and will not be capable of acting as a moderate base.

In the present invention, on the other hand, the substrate is selected so as to be bi-functional, with a first property of providing a support surface which has high surface area to which a metal phthalocyanine can be adsorbed and thus to immobilize the phthalocyanine on the surface of the substrate, and with a second property of providing base groups such as amine groups which stabilize and significantly increase the active life in terms of the oxidation reaction activity of the phthalocyanine catalyst.

The difference between the combination catalyst of the present invention and the supported catalyst of the prior art is evident from the higher catalytic activity of the combination catalyst in accordance with the present invention. For example, a catalyst prepared in accordance with the present invention achieves a turnover number of approximately 2,000. The catalyst of U.S. Patent 5,162,279, on the other hand, achieved a turnover number of 74 to 270 in the Examples.

The catalyst support preferably also possesses other desirable properties, such as low resistance to air flow and good adsorption and distribution of catalyst. The combination of the highly developed absorptive surface and the flexible structure of the carbon fiber allows the usage of this fibrous composite catalyst for cleaning of large volumes of emissions. The aforementioned positive qualities of the carbon fiber when used it in combination with the metallic phthalocyanine to form a heterogeneous catalyst for the cleansing of mercaptans from emissions, guarantees and maintains a high level of cleansing even with increasing volume and speed of flow of emissions through the catalyst.

The combined use of the bi-functional substrate and metal phthalocyanine catalyst distinguishes the present invention from other known methods of catalytic oxidation of thiols and sulphides to inorganic thiosulphates or sulphates, and mercaptans to organic disulphides. The employment of the bi-functional substrate and metal phthalocyanine catalyst, such as an activated carbon material with a cobalt phthalocyanine derivative deposited thereon, has not been described in literature, particularly as a heterogeneous catalyst for the cleansing of vent-emissions of mercaptans. It is surprising that such a composite allows for an increased gas volume velocity through the catalyst while maintaining a prolonged high level of cleaning of mercaptans.

The composite catalyst has been tested industrially. Chemical plants which produce methionine use methyl-mercaptan, and it is known that the vent emissions of methyl-mercaptan may reach 30 mg/m³. When the catalyst composite according to the present invention was installed in the vent-emission system, the product of methyl- mercaptan oxidation, dimethyldisulfide, was measured as a gaseous component at the same concentration of 30 mg/m³. This means that the methyl-mercaptan is catalytically oxidized and the odor, which is inherent to mercaptans, is removed.

Certainly, the catalyst will oxidize mercaptans of a higher molecular weight or in higher concentrations. However, where the molecular weight of the mercaptan increases and the volatility of the product is lower, the reaction products may adsorb onto the catalyst surface, and the system may have to be modified to maintain a desired high level of efficiency. For example, a recirculating system may be provided to desorb the oxidation products from the filter, or the filter may be heated to a point above the sublimation temperature of the oxidation products in order to cleanse the filter.

It is also preferable to "fine tune" the catalyst to the acidity of the target mercaptan or sulfur containing compound. For example, when the combination catalyst is matched to a mercaptan, a dynamic equilibrium can be established in which the catalyst is easily and continuously regenerated.

The catalyst composite was tested in laboratory conditions as set forth below by cleaning the air of methyl- and ethyl- mercaptans, as a model for industrial vent-emissions. EXAMPLE 1

The supported phthalocyanine catalyst is prepared in the following manner:

In 200ml of distilled water, O.Olg of cobalt disulfo- phthalocyanine (CoDSPc) is dissolved, and into this solution, 4.2g of felt is placed for 20 hours. The solution is then poured off, and the catalyst composite removed and dried in air. In a similar manner, the other components of the heterogeneous catalysts as shown in Table I are prepared.

As the solvent, distilled water may be modified with additives with facilitate the solubility of phthalocyanines in water, such Na₂C0₃ (preferably from 1-5% w/w) , NaOH (preferably up to 0.05%) and any other solvent with alkaline properties (including ethanolamine, etc. ) .

The oxidation of mercaptans from air is carried out in a laboratory within a reactor setting. The reactor is a glass column with 32 mm diameter and 300mm height. In the middle part of this reactor, 4.2 grams of the previously prepared heterogeneous phthalocyanine catalyst is placed.

In the top part of the reactor, with atmospheric pressure, temperature of 25°C, and with a determined gas volume velocity as set forth in Table I, air containing 25-35 mg/m³ of methyl mercaptans is passed by the catalyst. In the reactor, adsorption of the mercaptans and of oxygen to the catalytic composite takes place, and they interact, forming dimethyldisulfide and water. The formed dimethyldisulfide and the reaction water, along with the air cleaned of methyl mercaptan, are tested for the methylmercaptan and dimethyldisulfide content with gas chromatography by "TSVET 164" and "LKHM-8MD" apparatus. The results of the experiments are presented in Table I. EXAMPLE 2

The cleaning of ethyl mercaptans from the air takes place in a laboratory setting using a catalyst prepared as in Example 1. In the top part of the reactor, with atmospheric pressure, temperature of 30°C, and with a determined gas volume velocity as set forth in Table I, air containing 25-35mg/m³ of ethyl mercaptans is passed through. In the reactor, adsorption of the ethyl mercaptans and of oxygen takes place, and their interaction on the surface of the phthalocyanine catalyst forms diethyldisulfide and water. The diethyldisulfide and water so formed, as well as the air cleaned of ethylmercaptan, exit from the bottom of the reactor. The air flow is analyzed for the content of the ethyl mercaptans and diethyldisulfide before and after cleaning with gas chromatography on "TSVET 560" apparatus.

The results of the experiments are presented in Table I. In addition, the results of cleaning air of methyl mercaptans with a known catalyst (described in Russian Certificate of Authorship No. 1801559, Application No. 4913238/26, published March 13, 1993) is presented.

TABLE 1 o. Content of CoPc Level of Cleansing on Felt, % Mass %, Relative to Volume Velocity

800 hr^" 1600 hr^"1 2500 hr

CLEANSING OF CH₃SH

CoDSPc-0.01 FELT ANM- 99.85 99.83 99.80 (cobalt disulfophthalo- cyanine), the rest activated nonweaved material (ANM) )

CoDSPc-0.16 FELT ANM-the 99.92 99.91 99.80 rest

CoDSPc-0.70 FELT ANM-the 99.93 99.92 99.91 rest

CoBPCSPc-0.15 FELT ANM- 99.85 99.83 99.84 the rest cobalt bis-[N- (4-hydroxy-phenyl)-N- (carboxymethyl)- sulfamoyl]-phthalocyanine

CoBPCSPc-0.03 FELT ANM- 99.80 99.80 99.79 the rest

CoBBCSPc-0.19 FELT ANM-the 98.74 98.72 98.71 rest cobalt bis[N-benzyl-N- (carboxy-methyl)sulfamoyl]- phthalocyanine

CoDSPc-0.12 Calcium 99.80 98.25 97.30 aluminate-the rest (KNOWN CATALYST)

CLEANSING OF C_>H₅SH

CoDSPc-0.16 FELT AMN-the 99.97 99.92 99.96 rest

The above data illustrates that the catalysts composite in accordance with the present invention — derivative phthalocyanine of cobalt deposited on an nonweaved activated carbon material in form of felt (experiments 1-6, 8) — guarantees a high level of cleansing of air of low-molecular mercaptans, at a low (about 800 hour^-1) as well as at a high volume velocity (to 2500 hr"¹) of emissions passage through the catalyst. By definition, volume velocity refers to the amount of gas cleaned by the volume unit of catalyst in a unit of time: m³/m³ hour = hour"¹. As seen from the Table, the catalyst of the present invention works at a given condition for 2,500 hours with a decrease in efficiency of not more than 0.05%, in contrast to the comparison catalyst of Sample 7, where the efficiency decrease was 2.5%.

The above-described catalyst composite allows for an increase of the volume velocity of gases that are passing through the catalyst by 2-3 times over those previously known, while maintaining the high level of the cleansing of mercaptans (98.7- 99.8%) .

It should be readily apparent from the above that the heterogeneous catalyst of the present invention can be useful for a number of applications such as an ingredient in garments or diapers, an ingredient in an inner sole or shoe insert, a deodorant, an in-line filter for an air-conditioning system, an ingredient in a paint mix for use in fertilizer plants or sewage treatment plants, etc.

Claims

What is claimed is:

1. A catalytic composite comprising a metal phthalocyanine complex deposited on a substrate, which substrate contains basic centers and possess the properties of a moderate base.

2. A catalytic composite as in claim 1, wherein the basic centers are provided in a sufficient amount to enhance and prolong the catalytic activity of the metal phthalocyanine as compared to a catalyst having no basic centers.

3. A catalytic composite as in claim 1, wherein the metal of the metal phthalocyanine is selected from the group consisting of cobalt, iron, nickel, chromium, manganese, zinc, vanadium, titanium, and molybdenum.

4. A catalytic composite as in claim 3, wherein the metal of the metal phthalocyanine is cobalt.

5. A catalytic composite of claim 1, wherein the metal phthalocyanine is selected from the group consisting of cobalt disulphophthalochanine, cobalt bis-N-(4-hydroxyphenyl)-N- carboxymethyl sulfamoyl phthalocyanine, and cobalt bis-(N-benzyl-N- carboxymethyl)-sulfamoyl phthalocyanine.

6. A catalytic composite as in claim 1, wherein said substrate is selected from the group consisting of zeolites, polymers, and activated carbon.

7. A catalytic composite as in claim 6, wherein said activated carbon is in the form of fibers.

8. A catalytic composite as in claim 6, wherein said activated carbon is in powder form, granular form, or pellet form.

9. A catalytic composite as in claim 6, wherein said activated carbon is in the form of a carbon fiber felt.

10. A catalytic composite as in claim 6, wherein said activated carbon is in the form of woven fibers.

11. A catalytic composite as in claim 6, wherein said activated carbon is in the form of non-woven fibers.

12. A catalytic composite as in claim 1, wherein said substrate is selected from the group consisting of polyurethanes, alumina, calcium aluminate, modified silica, and acrylic fibers.

13. A catalytic composite as in claim 12, wherein said acrylic fibers are selected from the group consisting of acrylonitrile; acrylonitrile copolymerized with acrylic acid, methacrylic acid, allylsulfonic acid, salts of these acids, acid chlorides acid amides, N-substituted derivatives of vinyl amide, vinyl chloride, vinylidene chloride, alpha-chloroacetonitrile, vinylpyridines, vinylbenzenesulfonic acid, and alkaline earth metal salts thereof; and copolymers thereof.

14. A catalytic composite as in claim 1, wherein said substrate has a surface area of from 100-3000 m/g.

15. A catalytic composite as in claim 1, wherein said metal phthalocyanine is present on said substrate in an amount of from 0.001 to 2.5% by weight based on the weight of the substrate.

16. A catalytic composite as in claim 15, wherein said metal phthalocyanine is a cobalt phthalocyanine or cobalt phthalocyanine derivative, and wherein said substrate is an activated carbon fiber having basic centers.

17. A catalytic composite as in claim 1, wherein said metal phthalocyanine is present on said substrate in an amount of from 0.005 to 1.5% by weight based on the weight of the substrate.

18. A catalytic composite as in claim 1, wherein said substrate is carbon fiber, and wherein said metal phthalocyanine is present on said carbon fiber in an amount of from 0.01 to 0.7% by weight based on the weight of the carbon fiber.

19. A catalytic composite comprising activated carbon fiber having a cobalt phthalocyanine deposited thereon.

20. A process for the conversion of low molecular mercaptans and oxygen to dialkyl sulfides and water, comprising reacting said low molecular weight mercaptans with an oxygenating agent in the presence of a catalyst composite comprising a metal phthalocyanine deposited on a substrate, which substrate contains basic centers and possess the properties of a moderate base.

21. A process as in claim 20, wherein said metal phthalocyanine is cobalt phthalocyanine.

22. A process as in claim 20, wherein said substrate is activated carbon.

23. A process as in claim 22, wherein said activated carbon is in the form of fibers.

24. A process as in claim 22, wherein said activated carbon is in powder form, granular form, or pellet form.

25. A process as in claim 22, wherein said activated carbon is in the form of a carbon fiber felt.

26. A process as in claim 22, wherein said activated carbon is in the form of woven fibers.

27. A process as in claim 22, wherein said activated carbon is in the form of non-woven fibers.

28. A process as in claim 20, wherein said process is carried out in a gas phase.

29. A process for forming a composite catalyst, comprising dissolving a metal phthalocyanine in an aqueous solvent, placing a substrate material having basic centers into this solution, pouring off the solution, and drying the material to form the composite catalyst.

30. A process for forming a composite catalyst, comprising forming a solution of a cobalt phthalocyanine in water, placing activated carbon fiber into this solution, pouring off the solution, and drying the composite catalyst.