Aerosol Catalysis – Path Of Efficiency Increase
Aerosol catalysis – path of efficiency increase
of chlorine containing organic
waste catalytic processing
E.A. Pavlyuk, M.A. Glikin, D.A. Kutakova
State Design and Research Institute of Chemical Engineering "Khimtekhnologia",
Vilesov st. 1, 93400 Severodonetsk, Lugansk region, Ukraine
fax: (06452) 25367, e-mail: nio12@ixt.lg.ua
It is not a secret for anybody, now in a chemical industry the tendency of usage of not polluting environment manufacturing processes is boosted. From the point of view of an ecology the greatest hazard is introduced with productions which are letting out chlorine containing organic products, including vinylchloride, phenyl tetrachloride etc.
The problem of waste processing of the indicated productions is one of the actual ones. These wastes are multicomponent, not readily divisible and toxicological dangerous mixtures of chlorine containing components. The offensive feature of these wastes is fact, that almost all of them are xenobiotics, i.e. products that are not having clones in the nature, and the nature does not have natural means of strifing with them.
The majority of present methods of chlorine containing organic waste processing to a certain extent have reached the capabilities. The method of chlorine containing organic waste rendering with the help of incineration is unsuitable, as it results in formation of such high-toxic products as dioxins. Besides the incineration requires the large consumption of an overload fuel. The conditions of realization of process and structure of flue gases result in rapid wear of the equipment.
Most perspective in a direction of mining of ecological secure know-how of chlorine containing organic waste processing is the catalytic method. It is dispossessed of the majority of the indicated lacks of incineration. The primary goal of the given method application is the search for effective catalytic systems.
The catalyst should be optimal on activity, selectivity and duration of usage in the given process. The high activity, as is known, is reached by
maintenance of a developed surface per unit mass of catalyst. For this purpose, as a rule, disperse a fissile phase on a developed internal surface of the specially cooked porous carrier. Under our items of information the American Geon Corporation for processing of vinylchloride waste tenders such catalyst. The catalyst contains precious metals of platinum group on the carrier g-Al2O3. One of the main requirements to a catalyst is a capacity of the carrier to save a given degree of dispersion of a fissile phase during enough long burn-time. Also it is necessary, that the pattern of pores would not limit reaction speed by processes of diffusion of reactants and products in pores, would allow to avoid originating of gradients of concentration in a volume of catalyst.
The poisoning and gumming-up of a surface of catalyst by products of gumming, coking, salts entail loss of its catalytic activity. At usage of the given type of catalysts the relevant property of the carrier is the mechanical strength, abrasion resistance.
One of perspective versions of chlorine containing organic waste catalytic processing is the know-how of aerosol catalysis. It is grounded on usage of finely divided catalytically by fissile component carrier-free, filling a reaction space as a solid aerosol.
Main component unit of the laboratory installation intended for realization of system researches to efficiency of know-how of aerosol catalysis was the reactor a diameter of 50 mms and altitude of 1 m, in a reactionary zone where the active materials are mated a pseudo-liquefied layer of inert fragments and continuously sitting flow finely divided catalytically. The high degree of dispersion of fragments of an aerosol is supported at the expense of effect on catalyst of pseudo-liquefied inert fragments. It is necessary apart to note, that the applying of an aerosol of the smallest fragments makes possible the solution in classic catalysis of a problem of deposition on a surface of catalyst of salts and coking. Due to the mechanical activation the fluidized bed of solid inert particles, executing functions of a ball mill, removes fragments of contaminant from a catalytic surface.
The flow finely divided catalytically of fissile fragments imitates in a zone of reacting pattern of classic catalyst. The fairness of a fissile surface provides full oxidation organic component of waste up to thermodynamic of steady products: dioxide of carbon and water. The bound chlorine of components of waste thus transforms to hydrogen chloride.
During laboratory researches, as catalyst for process of steep chlorine containing organic waste oxidation the personal ferric oxides, brass, chromium, manganese and their mixture were used. An oxidizing and solubilizer air was used. The researches were carried out on separate matters, model mixes and substantial vinylchloride waste. An estimation of efficiency of a catalytic system conducted on value of ultimate load on waste per unit mass of catalyst in unit of time, which characterizes maximum quantity of withdrawal, processed by this catalyst, from practically 100 % by a rate of oxidation.
The experimental data demonstrate higher activity of catalyst located in a reactionary zone in a condition of an aerosol, as contrasted to conventional.
The investigated catalysts on efficiency during the chlorine containing organic waste steep oxidation can be arranged in a following order:
Cr2O3 > Co2O3 > CuO > MnO2 > Fe2O3 > NiO
The analysis of the obtained number of activity of catalysts demonstrates that most fissile is the contact on the basis of oxide of chromium. It is expedient to apply to the solution of only ecological problems less toxic and accessible catalyst on the basis of ferric oxide (III).
For processing of vinylchloride waste with salvaging and return of bound chlorine it is recommended as base for tests to use catalyst on the basis of oxide of copper, as the ferric chloride is a catalytic poison for catalyst hydroxychlorination of ethylene (CuCl2).
Depending on a problem of know-how two solutions are possible: neutralization or utilization of chlorine. At the neutralization the hydrogen chlorides by the alkaline agent calcium or sodium chlorides are formed. If it is necessary of chlorine utilization the gas outlet can be recycled into technological cycle of the main production, for example in vinylchloride production to stage hydroxychlorination of ethylene.
The system researches, conducted in laboratory conditions, have shown, that the method of rendering of waste in conditions of aerosol catalysis has no limitations neither on a modular condition of waste, nor on a quality and quantitative structure. Besides the offered know-how, except for effective rendering, allows utilizing hydrogen chloride, approximating, thus, production of a main product to the status resources-economy of ecological secure know-how.
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