The method of obtaining zelenoglazoe catalyst selective oxidative decomposition of hydrogen sulfide

 

(57) Abstract:

Method for obtaining Zelenoglazoe catalyst selective oxidative decomposition of hydrogen sulfide, comprising the grinding of coal, granulation and carbonation. Different way that gas coal pulverized powder of iron oxide, taken in an amount of 0.5-5.0 wt.%, to the content of particles with a size of 100 microns over 60%, followed by granulation of the mixture in the presence of water to obtain spherical granules, carbonation them in an inert atmosphere at 700-800oC on the residual content of volatile substances to 12% and steam activation at a temperature of 750-850oC to Abgar 30-40%. The method allows to obtain a catalyst with high activity, allowing complete conversion of hydrogen sulfide at low temperature and high speed gas flow. 1 C.p. f-crystals, 1 Il., 10 table.

The invention relates to a method for producing a catalyst for gas purification from hydrogen sulfide.

Hydrogen sulfide is one of the most toxic and at the same time widespread industrial pollution of the air environment. Significant emissions of hydrogen sulfide occur during the extraction of oil and gas. In some cases, when the extraction of oil seanie large quantities of hydrogen sulphide does not allow to use them due to the high corrosiveness.

One of the promising methods comprehensive gas purification from hydrogen sulfide is a direct oxidation catalytic decomposition on the number of metal-containing catalysts [S. Tamaka, U. Bood; Cham. Pharm. Bull., 1974, 22, 11, 2303; E. Richter, Catal. Today, 1990, 7, 93].

To reduce the cost of the process was proposed using as catalysts residues hydrogenization brown coal containing Nickel or iron [Ed. St-in the USSR N 1761236, 1992]. However, the depth of cleaning regardless of the number of hydrogen sulphide does not exceed 95-97%.

The closest to the invention is a method for Zelenoglazoe catalyst oxidative decomposition of hydrogen sulfide, which is that on the spherical carbon granules obtained by the crushing of coals, granulation and subsequent carbonization of the granules, causing acetylacetonate complex of iron from its solution in acetone, followed by its decomposition in nitrogen atmosphere [Y. C. Maximov, and other Izv. Russian Academy of Sciences, ser. chem., 1997, 1, 86-90]. The catalyst showed high activity in the decomposition of hydrogen sulfide 250oC and flow rate of 1500 h-1.

The technical result achieved by this invention is:

what I catalyst by reducing energy, resources consumption process by eliminating many of the technological stages that use electricity and expensive chemical reagents.

2. Improving the efficiency of the catalyst by increasing its catalytic activity and mechanical strength, wear due to the spherical shape of the granules and, as a consequence, the performance of the treatment process in General.

3. The expansion of raw materials production of catalysts on carbon carriers due to the inclusion of new classes of coals and cheap non-deficient natural iron compounds.

4. The improvement of environmental conditions of the production of catalysts by eliminating the wet stages of drawing, forming environmentally hazardous effluents, and elimination of chemicals, creating the danger of harmful gas emissions.

The technical result is achieved in that in the method of obtaining Zelenoglazoe catalyst selective oxidative decomposition of hydrogen sulfide, comprising the grinding of coal, granulation, carbonization gas coal pulverized together with a powder of iron oxide, taken in an amount of 0.5-5.0 weight. % (based on elemental iron to soderjaniyu them in an inert atmosphere at a temperature of 700-800oC content of volatile substances to 12% with subsequent steam activation at a temperature of 750-850oC to Abgar 30-40%. Thus, the iron oxide is added to gas to coal in the amount of 2.5% (based on elemental iron.

The invention is illustrated as follows.

Gas coal that meets the conditions of the process (for example, brand G6 Kirov mine Kuzbass), crushed, for example, jaw and hammer crushers to fractional amount of less than 2.0 mm, is mixed in mixer brush with iron oxide, served there in the amount of 2.0 to 3.0 wt.% [in the calculation of elemental iron and given the loss of organic mass of coal (WMD) with further heat treatment] , and further ground in a ball mill for a time, for example 8 minutes, providing dust fractional composition containing 100 μm of not less than 60%. Dust fractionized with the Department and return to the regrinding of larger particles and then granulated on a plate granulator 2% aqueous solution of sulfide-alcohol stillage (class lignosulfonate, waste hydrolysis of production) used to improve wetting of the dust as a surfactant, to obtain pellets of size 2-3P>oC to a residual moisture content of less than 10%, then carbonitride in an inert environment of volatile substances at a temperature of 700-800oC in a rotating drum muffle furnace by heat transfer through the wall from the flue gases moving countercurrent to the processed material, which ensures the speed of temperature rise of the material does not exceed 10 deg/min, to avoid the destruction of the granules under intensive removal of volatile substances to a residual content of not higher than 10%. The last stage of the preparation of the catalyst is steam-activation of the carbonized granules, which is carried out in a fluidized-bed reactor with a mixture of steam and flue gases at a temperature of 750-850oC to Abgar 30-40%.

Schematic diagram of receiving iron-containing catalysts for direct decomposition of hydrogen sulfide represented in the drawing.

This process imposes requirements on quality of coal: ash content not exceeding 8%, the sintering thickness of the plastic layer (test indicator) within 10-15 mm. These requirements are met by natural gas coal technology group G6, significant reserves which are available in the Russian Federation (To the ACCA, the quality indicators which are listed in the table. 1.

Crushing ratio has a great influence on the shape and density of the granules and the formation of structural strength properties of the granules of the catalyst in the subsequent stages of processing.

The carbonization process generates the initial porous structure and provides strength properties of the material. The quality of carbonizate also depends on the mode of conducting the carbonization: the rate of rise of temperature and the end temperature of the process.

The heating rate determines the intensity of the emission of volatile from the processed pellets: with a high rate of heating (especially in the regime of thermal shock) emitted per unit of time a large amount of volatile substances can break granule or, at best, to greatly reduce its strength. Slow heating significantly increases the duration of the process, which negatively affects its economic performance and, therefore, on the cost of the catalyst. Temperature carbonization 700-800oC should provide a fairly complete removal of volatile substances and completeness of the formation strength and initial porosity. Lowering the temperature below 700oVklada in strength and structural properties, increases the duration of the process, i.e., it is impractical from a power-saving considerations. The influence of the conditions of carbonization gentoolinux of pellets, derived from dust 8 minutes of grinding on the quality indicators carbonizate are given in table. 2.

As can be seen from the table, most durable reactive granules obtained according to the modes of experiments NN 2-6 parameters of the heat treatment in the range: the speed of temperature rise of 5-10 deg/min, final temperature of 750 - 850oC. the Most favorable in relation to the strength of obtained carbonizate is N mode 3, which is taken as optimal. Premium quality carbonizate obtained under optimum conditions of all stages of the process and used to obtain catalysts for direct decomposition of hydrogen sulfide, are given in table. 3.

As can be seen from the table, the result is carbonized with low content of volatile substances, high strength pellets and primary porous structure, represented by small amounts of macro - and mesopores and already high enough volume of micropores.

Activation is a final stage in the process of preparation of the catalyst, the purpose of which is the development of the porous structure to which Is carried out at a sufficiently high temperature gas-oxidants, the most effective of which is water vapor.

Temperature of the process should ensure that the course of the reaction in the entire volume of the granules with the formation of a developed porous structure that is feasible in the temperature range of 750-850oC. higher temperatures (above 850oC) lead to the so-called surface obaro, in which the interaction takes place in the surface layer of the granules, causing a loss of mass of the catalyst, its strength, and leads to deterioration of the porous structure by increasing the volume of macropores. Lower temperatures (below 750oC) do not provide flow endothermic reaction of interaction of H2O + C, in other words, the activation does not occur or it occurs partially.

For the conditional exponent activation adopted Abgar - the amount of mass loss during the activation process, when this is not taken into account the mass loss due to the removal of residual amounts of volatile substances. The duration of activation at the selected temperature and constant composition and consumption activating agent (steam + flue gases) is determined by abharam ensuring a favorable combination of high screening the granules, obtained at the optimum temperature at all stages of the process, on the quality of the catalyst are given in table. 4.

A thorough testing of the activation mode due to the importance of this stage in the formation of catalyst activity. The possibility of fine adjustment of the operating parameters at activation in the fluidized-bed reactor has allowed to establish that the most acceptable from the standpoint of quality indicators and economic indicators is mode: activation for 120 minutes at a temperature of 750-850oC. This mode is taken as optimal. Extended characteristics of the catalyst obtained at the optimum technological parameters at all stages of the process are presented in table. 5.

As determined experimentally, nor the type insertion compounds of iron, nor its concentration within those of the small quantities that are used in the preparation of catalysts have no effect on the settings for any of the stages, and the porous structure and the strength of the granules of the catalyst obtained in the stages of carbonization and activation. However, as was established using methods mössbauer spectroscopy and x-ray diffraction, is in a highly active form of iron, are crucial for activity and performance of the catalyst.

On the formation of iron-containing components in the process of obtaining iron-containing catalyst, and hence the activity of the catalyst in the decomposition of H2S specifies influenced by the stage of preparation of spherical granules: the concentration and type of iron compounds and the degree of joint grinding. Modes of carbonization and activation does not affect the nature of the phase transitions of iron compounds at these stages. Below are examples of the preparation of catalysts with different concentrations applied in coal, iron-containing component and different joint grinding of the mixture. All other stage was carried out under the above optimal processing conditions.

The resulting catalysts were tested in two ways: 1) decomposition of H2S contained in the noise with a bulk velocity 1500-20004 h-1hydrocarbon gases (e.g. methane) in concentrations of 0.5-1.0%, in the presence of stoichiometric amount of oxygen at a temperature of 150-200oC; 2) decomposition of H2S contained in the exhaust gas mixture Claus process logicheskie scheme, shown in the drawing and the above description of the process gas coal G6 Sch. Kirov Kuznetsk basin crushed in jaw and hammer crushers to the fractional size of 2.0 mm, are mixed in the mixer brush with iron oxide, served there in the amount of 2.5 wt.% in the calculation of elemental iron, and then the mixture was ground in a ball mill for 8 minutes. Then the dust was fraktsionirovanii with the Department and return to the regrinding of particles larger than 100 μm, and then was granulated on a plate granulator with a 2% aqueous solution of sulfide-alcohol stillage to obtain pellets of a size of 2-3 mm, Then wet granules were dried on a belt drier at a temperature of 80-90oC to a residual moisture content of less than 10%, was carbonitriles with the speed of temperature rise of 5 ° /min to a temperature of 800oC in a rotary muffle furnace type "pipe in pipe" and was activated in a fluidized-bed reactor at a temperature of 825oC for 120 minutes. Granules prepared catalyst was cooled, analyzed, and tested for catalytic activity (sulfur-retaining capacity) in the decomposition of hydrogen sulfide in the 1st direction.

Testing of the catalysts was carried out on the installation flow type n is steel), when the gas flow rate 2000 h-1and a temperature of 200oC. Evaluated the catalytic activity at 100% conversion of hydrogen sulfide (up to overshoot, i.e. before the appearance of hydrogen sulfide at the outlet of the reactor). Control breakthrough was made by deletion of the last catalytic reactor gas through the solution, a solution of cadmium chloride. Recorded volume passed through the catalyst to the leakage of gas, including hydrogen sulfide, and calculated sulfur-retaining capacity of the catalyst. Prior to testing, the catalyst was subjected to mandatory preparation for catalysis is processed in a stream of nitrogen at 400oC.

Examples 2 and 3. The catalysts prepared according to example 1 with the difference that the co-grinding is 5 minutes (for example 2) and 10 minutes (3).

Examples 4 and 5. The catalysts prepared according to example 1 with the difference that the concentration of deposited iron oxide is 0.5 wt.% (4) and 5.0 wt.% (5) in the calculation of elemental iron.

Example 6. The catalyst prepared according to example 1 with the difference that as compounds of iron using iron acetylacetonate in an amount of 2.5 wt.% in the calculation of elemental iron.

Example 7. It is known that in the mineral part of the fossil is probably also undergoing phase transformations and acquires catalytic activity in the process. In this regard, for comparison was prepared and tested as in example 1 carbon carrier with the difference that the formation of pellets in coal is not made the connection of iron.

Examples 8, 9 and 10. For comparison were prepared iron catalyst on a carbon carrier, obtained according to example 7, using the traditional method of impregnation of the carbon carrier with solutions of iron salts on the prototype - acetylacetonate Fe (8 and 9) and nitrate Fe (Ave 10). To accomplish this, the finished carbon carrier was applied by impregnation to 2.5 wt.% iron (in terms of elemental Fe) from a solution of iron acetylacetonate in acetone (8 and 9) and an aqueous solution of iron nitrate (Ave 10). Granules media after complete absorption of the solution was dried to remove solvent, and then recovered by heat treatment in a nitrogen atmosphere at 400oC (8 and 10) or hydrocarbon vapors at 650oC (9) for the decomposition of iron salts. Next, the catalyst was tested as in example 1. Conditions of preparation of the catalysts and the results of their testing are presented in table. 6.

As can be seen from the rez is -6, 8-10), regardless of the production method, the type of applied compound and its concentration was increased catalytic activity compared to the activity of the carbon source of the medium (7). Most active systems are obtained according to the proposed method by introducing-Fe2O3in the coal dust and the subsequent stages of mechanochemically processing.

Based on the results of research performed using mössbauer spectroscopy and x-ray diffraction, the joint grinding has a significant influence on the catalytic activity and, accordingly, the sulfur-retaining capacity of the catalyst. The highest sulfur-retaining capacity of the catalyst 8-minute grinding; reduction of time grinding up to 5 minutes significantly reduces sulfur-retaining capacity of the catalyst and increase the time to 10 minutes does not contribute to the activity of the catalyst, even slightly decreasing, which is probably associated with a decrease in the dispersion formed at the subsequent stages of processing of the active phase-Fe2O3.

The quantity-Fe2O3constituting the precursor of the active phase of the catalyst, also has its influence on KATALITIChESKIE concentration (other 4 and 5) negatively affect careercast catalyst: the first due to lack of Fe to provide the desired catalytic activity, the second is likely associated with a decrease in the dispersion formed at the subsequent stages of processing of the active phase-Fe2O3.

From the obtained results it also follows that the nature of the precursor of the active phase has a significant influence on the catalytic activity of the catalyst. When using as a precursor of the active phase organic derivative of iron (other 6) in the form of its acetylacetonato complex sulfur-retaining capacity of the catalyst prepared according to the proposed method, was reduced more than twice.

Catalytic activity and, accordingly, the sulfur-retaining capacity of the catalyst obtained according to the proposed method, more than an order of magnitude greater than the known catalysts (for example, 8, 9 and 10) obtained by conventional impregnation of the carbon media solutions, both organic and inorganic iron salts. Restorative treatment impregnated catalyst in hydrocarbon vapors at 650oC (9) resulted in a significant decrease in the catalytic aktivnosta showed evidence of mössbauer spectroscopy and x-ray diffraction, was the decrease in the surface concentration of Fe2O3.

Using the most active catalyst obtained in example 1 was acquired in the mode of decomposition of hydrogen sulfide present in the gas of the same composition as in the testing of catalysts. The results are shown in table. 7.

From the results of the table shows that the maximum activity of the catalyst in the decomposition of hydrogen sulfide, as measured by careercast, is achieved at temperatures of 150-200oC. temperature Rise above 200oC is impractical because the conversion of hydrogen sulphide does not increase, but, as you know, possible loss of selectivity of the catalyst as a result of local overheating, leading to the formation of sulfur dioxide. Lowering the temperature below 150oC causes rapid leakage of H2S.

Optimal flow rates sulfurous gas, as can be seen from the table. 7, can be considered within 1500-2000-1. At this flow rate the maximum number of missed gas per unit mass of catalyst at 100% conversion of hydrogen sulfide. The increase in flow rate above 2000 h-1leads to rapid leakage of H2S, and its reduction demonstrate the advantage of the obtained catalyst in the oxidative decomposition of hydrogen sulfide, contained in hydrocarbon gases, in comparison with the known.

Two catalyst: the most active, obtained in example 1, and less active, obtained according to example 2 with less time joint grinding, was tested in the decomposition of hydrogen sulfide contained in the exhaust gas of Claus process, according to the above mode (2-s direction). Testing of the catalysts was carried out on made in USA running install AMI-2000 reactor volume 27 cm3and the height of the catalytic layer 200 mm under the conditions Used the most close to real and are significantly more hard compared with the decomposition of hydrogen sulfide contained in the methane. This is reflected in a greater concentration of H2S, lower temperatures and the presence of a large number of water vapor (30%).

There were obtained samples of the catalysts according to the prototype and comparative trials. The results of the comparative tests are shown in table. 8.

As can be seen from the presented data, zhelezouglerodistye catalyst (inventive) example 1 shows a significantly higher activity in the decomposition of hydrogen sulfide to elemental sulfur, than known catalysts. This featur>After the loss of activity of the catalyst was recovered by treatment with an inert gas at a temperature of 400oC, removing from the surface the remains of elemental sulfur, and then (or immediately, without pre-treatment), the catalyst is subjected to the second stage of regeneration by processing the gas-vapor mixture at the optimum stage mode activation mode of preparation of the catalyst. Next, the catalyst was re-used in the decomposition of hydrogen sulfide. In table. 9 shows the conditions of regeneration of spent optimal catalyst (obtained in example 1 and the test results of the regenerated catalyst to the 1st direction at a temperature of 150oC and flow rate model gas above specified structure 2000 h-1.

As the table shows, the most effective method of regeneration - conducting heat treatment in an oxidizing atmosphere according to the mode of activation of the granules in the process of preparation of the catalyst (table. 4, experience N 9). Testing of regenerated catalyst on hard mode (2nd direction) showed recovery of its activity only 50% (table. 10), however, the selectivity of the catalyst remains at a sufficiently high level. This allows the use of regenerated katal the proposed method has high catalytic activity, allows complete conversion of hydrogen sulfide at a lower temperature and a higher volumetric rate of gas supply. The catalyst has a high sulfur-retaining capacity.

1. The method of obtaining Zelenoglazoe catalyst selective oxidative decomposition of hydrogen sulfide, comprising the grinding of coal, granulation, carbonation, characterized in that the gas pulverized coal together with a powder of iron oxide, taken in an amount of 0.5-5.0 wt.% in the calculation of the elemental iron content of particles with a size of 100 μm, more than 60%, the mixture granularit in the presence of water to obtain spherical granules, carbonizing them in an inert atmosphere at a temperature of 700-800oC content of volatile substances to 12% with subsequent steam activation at a temperature of 750-850oC to Abgar 30-40%.

2. The method of obtaining Zelenoglazoe catalyst selective oxidative decomposition of hydrogen sulfide under item 1, characterized in that the iron oxide is added to gas to coal in the amount of 2.5% (based on elemental iron.

 

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