The catalyst for the oxidation of sulfur compounds

 

(57) Abstract:

The invention relates to the production of heterogeneous catalysts for liquid-phase oxidation of sulfur compounds (sulfur dioxides, verouderde, mercaptans) and can be used for purification of gas emissions and wastewater, energy, refining, petrochemical, chemical and pulp and paper industries.

Proposed heterogeneous catalyst for the oxidation of sulfur compounds containing active ingredient and a carrier - high-pressure polyethylene, characterized in that as component contains the oxide of antimony (III) and pyrite cinder, in the following catalyst components (mass fraction, %):

pyrite cinder - 33 - 37

the oxide of antimony (III) - 4 - 6

polyethylene - the rest. table 1.

The invention relates to the production of heterogeneous catalysts for liquid-phase oxidation of sulfur compounds (sulfur dioxide, hydrogen sulfide, mercaptans) and can be used for gas cleaning and wastewater, energy, refining, petrochemical, chemical and pulp and paper industries.

Known heterogeneous ka is kind and organic sulfur compounds [1] the Main disadvantage of this catalyst is unsatisfactory, the depth of oxidation of hydrogen sulfide and organic sulfur compounds to sulfur dioxide. Sulfur dioxide is hard to recover highly toxic component. The cleaning gas from the sulfur dioxide is in itself no less a problem than purification from hydrogen sulfide and serverance.

The closest in technical essence and the achieved effect to the present invention is a catalyst for the oxidation of sulfur compounds, containing as an active ingredient the active sludge (35 of 50) and medium - high density polyethylene (or polypropylene, polystyrene) [2]

The specified catalyst-prototype differs relatively little activity in the process of liquid-phase oxidation of sulfur dioxide, and also has significantly less activity in the oxidation of hydrogen sulfide and mercaptans in comparison with the proposed catalyst.

The aim of the invention is to increase the catalyst activity.

This goal is achieved by the fact that the catalyst for the oxidation of sulfur compounds (sulfur dioxide, hydrogen sulfide, mercaptans) contains as active ingredients pyrite cinder and oxide of antimony (III) and medium - high-pressure polyethylene in the following ratio, wt.

Pyrite cinder 33 37

The oxide of antimony (III) 4 6

Polyethylene is the quiet inserted into the mass media of high-pressure polyethylene. Instead of activated sludge is used a mixture of oxides of metals of variable valence pyrite cinder and oxide of antimony (III).

The proposed catalyst in comparison with the known has a higher total activity, but most significantly the activity of the catalyst is increased in the process of liquid-phase oxidation of sulfur dioxide. Using a specified catalyst for the oxidation of sulfur compounds is carried out in the liquid phase and flows mainly to thiosulfate or sulfates, depending on the oxidation conditions.

Testing the activity of the catalyst in the process of absorption and catalytic gas cleaning and SO2was carried out in the reactor of continuous operation when the film mode of the process. Absorbent, which used water, was fed into the reactor from above, the gas backflow from the bottom. For experiments we used synthetic gas mixture containing sulphur dioxide 2000 - 2500 mg/m3and volume concentration of oxygen of 10% which roughly corresponds to their content in the flue gases of thermal power plants operating on brown coal. Sulfur dioxide was supplied from a cylinder, and the reduction of oxygen was carried out by dilution of the gas mixture with nitrogen.oC; gas velocity of 0.14 m/s; the contact time of the gas-catalyst 3.6 sec; the ratio of the flow rate of the absorbent to the gas flow 0,00015; oxygen concentration in the gas 10% as the absorbent used water pH of 6.5 to 7.5.

The catalyst activity was evaluated according to the degree of purification of the gas mixture from the sulfur dioxide. This was determined by the concentration of sulfur dioxide in the gas mixture at the inlet and outlet of the oxidation reactor.

Catalytic oxidation of SO2to H2SO4in aqueous solutions is expressed by the following equation:

SO2+1/2O2+H2O H2SO4.

Therefore, additional controlled plant's effluent liquid-phase oxidation of SO2for completeness turning it into an H2SO4. The testing results show that using the proposed catalyst absorbed water SO2oxidized to sulfuric acid of not less than 96 99% versus 5 to 10% in the control experiment without catalyst.

Experiments to determine the activity of the catalyst in the process of liquid-phase oxidation of hydrogen sulfide and mercaptans oxygen was carried out on real wastewater of pulp and paper production secondary condensates residue of black school is the Odile in reactor periodic action with the following parameters: temperature 60oC; pressure 0.3 MPa; oxidation time 3 min; feed rate of air 10 20 h-1; the mass ratio of the catalyst waste water 1 5. The air in the reactor was carried out from the bottom using a special dispersant, provide good mass transfer.

The catalyst activity was evaluated according to the degree of oxidation of hydrogen sulfide and methylmercaptan in waste water, for this was determined by the concentration of H2S and mercaptan in the original and oxidized wastewater. The definition of H2S and mercaptan was carried out potentiometrically by GOST 22985-88.

High catalytic activity of the proposed catalyst is observed at the specified mixing ratio of the active basis of the catalyst pyrite cinder and oxide of antimony (III), especially activity in the process of liquid-phase oxidation of sulfur dioxide.

In addition, it is important that the mass fraction of the carrier in the catalyst was in the range of 57 to 65% Decrease in the mass fraction of the carrier of polyethylene in the composition of the catalyst is less than 57% leads to decrease in mechanical strength of the granules of the catalyst, and the increase in the mass fraction of the media more than 65% decrease in catalyst activity.

Example 1. Cat is Aut as follows. Mixing of the components and forming pellets of the catalyst is carried out at an industrial unit for the granulation of polyethylene with a minimum load of mixer 60 kg, so the components of the catalyst are taken in the following quantities, kg: pyrite cinder 19,8; oxide of antimony (III) 2,4; polyethylene 37,8. Active the basis of the oxides of metals of variable valency after a preliminary dry mixing and grinding them in a ball mill for 8 hours mixed with the carrier of the high-pressure polyethylene (LDPE) at a temperature of 120 130oC for 20 to 30 minutes Duration of mixing depends on the composition of the catalyst. After mixing the resulting mass is fed into a screw extruder, where with the help of special nozzles is formed in the form of pellets or rings required shape and size. For studies were made of the samples of the catalyst in the form of spherical granules with a diameter of 4 to 6 mm

Example 2. The catalyst composition, wt.

Pyrite cinder 33

The oxide of antimony (III) 6

Polyethylene 61

manufactured according to the technology described in example 1.

Example 3. The catalyst composition, wt.

Pyrite cinder 37

The oxide of antimony (III) 4

Polyethylene 59

manufactured by BR>
The oxide of antimony (III) 6

Polyethylene 57

manufactured according to the technology described in example 1.

The catalysts obtained in examples 1 to 4, and the catalyst-the prototype was tested for activity in the processes of liquid-phase oxidation of SO2H2S and mercaptan according to the methods described above, as well as stability within 200 hours the Results are given in the table.

Experiments to determine the activity of the samples showed that the introduction of the catalyst components in the ratio of examples 1 to 4, i.e. in the ratio provided by the invention allows to obtain highly active catalysts with high mechanical strength and stability. The proposed catalyst is substantially outweighed by the activity known.

The efficiency of absorption and catalytic gas cleaning and SO2in the presence of the proposed catalyst is 96 to 97% compared to 41.5% for the catalyst of the prototype. The proposed activity of the catalyst in relation to the oxidation of hydrogen sulfide is 98 to 99% and methylmercaptan 95 96% compared with 76.8% and 62.7 percent, respectively, for the prototype. The greatest increase in activity was noted in the oxidation dioxide is N 5 8 content components, lying outside the bounds provided by the invention. The composition of the sample and the test results of their activity and stability are also presented in the table.

Analysis of the results allows us to conclude that the ratio of the mass fraction of pyrite cinder to the mass fraction of oxide of antimony (III) must be within 1 (6 8,2). The change of this ratio of components in the direction of increasing the share of pyrite cinder (sample 5), and in the direction of increasing the share Sb2O3(sample 6), leads to a reduction in the overall activity of the catalyst.

The decrease in the mass fraction of the carrier in the catalyst below 57% (sample 7: the content of the carrier 55%), while maintaining the required ratio of the metal oxides in the composition of the active bases leads to an abrupt drop in the mechanical strength of the obtained sample. This entails rapid destruction of the catalyst in the catalytic reaction conditions and, therefore, reduction of service life. The increase in the mass fraction of the carrier above 65% (sample 8: the content of the carrier 66), while maintaining the desired ratio of metal oxides in the composition of the active framework entails a reduction in the overall activity of the catalyst.

The results of the tests about the ora is the best.

The use of the catalyst in the industry will improve the efficiency of wastewater treatment and gas emissions, reduce the size of technological devices, to carry out the cleaning process in more mild conditions. All this makes it possible to reduce capital and operating costs during the implementation of the cleaning process using this catalyst.

The catalyst for the oxidation of sulfur compounds containing active component on the carrier of the high-pressure polyethylene, characterized in that as the active component contains the oxide of antimony (III) and pyrite cinder at the following content, wt.share

Pyrite cinder 33 37

The oxide of antimony (III) 4 6

Polyethylene Ostalnoe

 

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