Catalytic reactor for synthesis gas production

 

Catalytic reactor radial type to produce synthesis gas refers to the devices used in the chemical industry for processing hydrocarbon gases. Contains plugged on one side of the gas distribution tube with a layer of catalyst. The catalyst is made in the form of a gas-permeable flat and corrugated strips, wound and fused with the gas distribution tube, with a gap between the coils with the formation of gas channels between the strips. The catalyst is a reinforced porous material containing as active components, rhodium, Nickel, platinum, iron, cobalt, rhenium and ruthenium. The gas distribution tube has perforations with a diameter of less than critical, and is equipped with a divider jets. The reactor is equipped with a device of the electric to run it. This design improves the efficiency of the catalytic conversion of methane into synthesis gas. 3 C.p. f-crystals, 2 Il.

The invention relates to chemical technology, namely reactors for processing hydrocarbon gases and can be used in devices for production of synthesis gas for further use it in C

It is known that synthesis gas is produced by reforming natural gas or vapor or carbon dioxide, or partial oxidation, or by a combination of all three methods. The presence of water, which usually accompanies the reformer, gives the shift reaction, which plays a significant role. Reforming with steam CH4+ H2O --> CO + 3H2;H = 206,3 kJ/mol; (1) CO2CH4+ CO2--> 2CO + 2H2;H = 246,9 kJ/mol; (2) parts. oxidation of CH4+ 0.5 O2--> 2CO + 2H2;H = -35,6 kJ/mol; (3) the shift reaction CO + H2O --> CO2+ H2;H = -40,6 kJ/mol. (4) the reaction of H2O - CO2reforming of methane is endothermic, run on Nickel-containing catalyst at temperatures 650-1040oC. Catalytic steam reforming to produce synthesis gas is quite expensive and energy-consuming process. This process goes with absorption of heat and can be carried out at different reforming catalysts. An alternative to steam reforming is the partial oxidation of methane is carried out by the lack of oxygen. Catalytic partial oxidation of methane is carried out in the framework is such as Ni, Rh, Ru, Pt, Ir and Pd.

The mechanism of formation of synthesis gas on the catalyst Ni/Al2O3[S. Shen, C. Li, Ch. Yu. Mechanistic Study of Partial Oxidation of Methane to Syngas over a Ni/Al2O3Catalyst. // Natural Gas Conversion V Studies in Surface Science and Catalysis., 1998 Elsevier Science B. V. v.119, p.765-770] the following: oxygen reacts with the surface of the Nickel, forming NiO, and methane dissociates on the surface of Ni in the form of carbide, and the hydrogen is released and immediately desorbed, then the carbide reacts with NiO, forming co and CO2.

Currently it is generally accepted that the production of synthesis gas (indirect) goes first through the complete combustion of methane with the formation of CO2and H2A: CH4+ 2O2--> CO2+ 2H2OH = -802,6 kJ/mol (5), and then the remaining methane H2O - CO2- reforming reactions (1) and (2) is converted to CO and H2[D. Wolf, M. Hohenberger, M. Baerns. External Heat Mass Transfer Limitations of The Partial Oxidation of Methane over Pt/MgO Catalyst for Consequences for Adiabatic Reactor Operation.// Ind. Eng. Chem. Res. 1997, 3633, 3345-3353]. Direct formation of synthesis gas through the reaction of CH2with O2carry on Ru/TiO2the catalyst or Rh or Pt catalysts at high temperatures (~1273 K) and short contact times (~10 MS) [P. M. Torniainen, X. Chu, L. D. Schmidt. Comparison of monolith - supported metals for direct oxidation of methane to syngas. //Journal the Ana is thermal reactor operation. Due to the high ekzotermicheskie reaction (5) in the first part of the fixed catalyst layer appear "hot spots". For example, modelling of adiabatic reactor with a porous layer containing Ni/Al2O3the catalyst showed that for raw materials CH4/O2ratio 1,67 temperature "hot spots" may be above 1773 K under the assumption that the combustion of methane and reforming are performed sequentially [A. M. Groote, G. F. Froment, Simulation of the catalytic partial oxidation of methane to synthesis gas. //Appl. Catal. A General 138 1996, p.245-264]. Because of this catalytic partial oxidation of methane is carried out at low contact times (fractions of seconds) and thermal conductivity layer is not less than 0.15 j/(s m K) [M. Fathi, R. H. Hofstad. T. Sperle, O. A. Rokstad, A. Holmen. Partial oxidation of methane to synthesis gas at very short contact times.// Catalysis Today 42. 1998, R. 205-209].

It is known that for the catalytic partial oxidation of methane can be used a catalyst containing as the active component, rhodium, Nickel, platinum, palladium, iron, cobalt, rhenium and ruthenium. Most active in this series are rhodium and Nickel. The area recommended temperatures for these catalysts is in the range of 800-1000oWith and depends on the ratio of CH4/O2. Most of selecti the comfort of various reactors for production of synthesis gas. Known fluidized bed reactor [S. S. Bharadwaj and L. D. Schmidt. Synthesis gas formation by catalytic oxidation of methane in fluidized bed reactors.// Journal of Catalysis. 1994, v.l46, p.11-21], representing a quartz tube with a diameter of 1.9-3.2 cm, height 18-24 cm, which covered the catalyst grains with a diameter of 80 MK. He is a bearer of Al2About3, which cause the active components in the form, wt.%: 0.5 rhodium, 1,0 Nickel, 0.5 to platinum. The contact time at a temperature of 850oWith in the range of 0.1-0.5 C. the Experiment is carried out on the methane-oxygen mixtures at molar ratios of CH4/O2within 1-2. The greatest activity of rhodium, a few lesser - Nickel and the lowest - in platinum. Achieved in the experiments, the degree of conversion of methane to Rh and Ni varied from 1 to 0.87 for Pt from 0.86 to 0.48 by increasing the concentration of methane from 18-20% to 30%. Because of the good properties on the heat transfer fluidized bed reactor allows the catalytic partial oxidation of methane in nearly isothermal conditions. Research reactor with a fluidized bed of catalyst Ni/Al2O3showed that the temperature gradient across the layer is not higher than 10oWith 800oWith, however, after 100 h of operation, the layer was supervivencia (5.6 wt.% (C) [J. Yaying, L. Wenzhao, X. Hengyong, Y. Chunying.// Partial oxidation of the catalyst particles, which is observed at high temperatures (>850oFor Ni and Pt and >950oFor Rh catalysts).

Using two successive reactor with a fixed bed of catalyst synthesis gas is produced [R. Zhi-yong, D, Chao-yang, S. Shi-kong.// New two-stage process for catalytic oxidation of methane to synthesis gas. Ranliao Huaxue Xuebao, 28(4), 2000, p.348-351] by introducing oxygen in two stages, thus avoiding the appearance of "hot spots" above 1000oC. Under appropriate conditions on the catalyst Ni/La2O3/MgAl2O3-Al2O3it was achieved: the conversion of CH4- 93%, N2and WITH selectivity - 97 and 98%, respectively. The disadvantages of the considered reactor includes a two-phase process for production of synthesis gas, comprising two fixed catalyst layer, exploded in space. For the process in the reactor it is necessary to have two site preparation gas mixture.

The reactor with a honeycomb catalyst (honeycomb type) proposed by Coronaca and others [J. D. Korchnak, M. Dunster and A. English. The Patent Cooperation Treaty WO 90/06282. PTC/US 89/05369, assigned to Davy McKee Corporation] and Winkelmann and others [M. F. M. Zwinkels, S. G. Jaras, P. G. Menon and T. A. Griffin//Catal. Rev. -Sci. Eng., 35 (1993), p.319]. In the patent Coronaca partial oxidation of methane improved by the addition of water in raw materials in molar soo is up>. Under these conditions, the carbon is not deposited on the catalyst, and the temperature of the gas mixture at the inlet below 93oWith the Autoignition temperature of the mixture (usually 288-593oC). Swinkels used cell catalyst with the number of cells 300/inch21 m in diameter and 2 m in length, containing noble metals Pd and Pt on SEO2l2About3powder media. Analysis of products of combustion and the longitudinal temperature profile of the layer showed that at the entrance to the cell catalyst is the combustion of methane with subsequent reaction of the reforming and shift, which produces synthesis gas. Schmidt with employees also used cell catalyst coated with noble metals deposited on a ceramic foam, and the alloy of Pt-Rh mesh fabric [ D. A. Hickman and L. D. Schmidt.// Science. 259 1993, p. 343]. They found that the reaction of partial oxidation of methane is determined by the combination of transport and kinetic effects: diffusion of reactants to the catalytic surface is a function of the flow velocity and the geometry of the catalyst, while the reaction kinetics depends on the wall temperature of the catalyst and its nature. They also showed that with decreasing contact time of from 10 to 0.1 MS increases Convair> International Natural gas Conversion Sympozium, South Africa, 1995], using cell Nickel spent catalyst partial oxidation of methane at high pressure 12 ATM, temperatures above 700oAnd the ratio of CH4/O2=2:1. The composition of the products at the exit equilibrium was, however, after 300 min was significantly nauglerozhivaniya catalyst.

Option paired warmth tubular reactor for the catalytic partial oxidation of methane is given in [I. Theophilos, V. Xenophon E.// Development of a novel heat-integrated wall reactor for the partial oxidation of methane to synthesis gas. Catal. Today.46(2-3), 1998, p.71-81]. It consists of a hollow heated ceramic tube, inside which is placed an aluminum tube with a wall thickness of 1 mm thick in the end portion (10 cm) outside and inside bifunctional Rh/Al2O3a catalyst. The amount of catalyst varies by drawing from one to four layers. Methanomicrobia the mixture flows inside the aluminum pipe. The contact time inside the pipe is 0,027 is 0.55, and on the outside - 0,11-0,22 C. a Large part of the heat generated from the combustion of methane is passed through the wall of the aluminum pipe to the outer catalytic film, which is endothermic steam or CO2reforming. Selecting the feed rate ishodniki pipe, you can control the position of the "hot spots" along the length of the catalytic layer, and the value of temperature of heating. In such a reactor with integrated heat exchanger is possible to control the temperature in the zone of combustion of methane at the same time significantly reducing the amount of "hot spots". Thermal coupling exothermic reaction (combustion of methane) and endothermic reforming reactions is a significant difference from traditional tubular reactor in which the catalytic layer is inside the pipe.

For the implementation of catalytic partial oxidation of methane was developed and tested in laboratory and industrial scale non-isothermal catalytic membrane reactor [C. Y. Tsai, Y. H. Ma, W. R. Moser and A. Dixon. Modeling and Simulation of a Nonizothermal Catalytic Membrane Reactor. //Chem. Eng. Comm. 1995, v. 134, p.107-132]. Industrial reactor has a set of membrane tubes with an internal diameter of 2.5 cm and a length of about 6 meters Inside the tubes (the reaction zone) serves natural gas with a flow rate of 5000 cm3/s and an oxidant (oxygen) is supplied from the external side of the pipe (operating area) with a flow rate of at least 1000 cm3/C. the Membrane tube has three layers: 1) the outside of the pipe caused a highly porous inert layer of the carrier - Al2Aboutrc="https://img.russianpatents.com/chr/948.gif" align="TOP">or SrCo0,8Feof 0.2O3-) thickness of about 1,77 mm, 3) from the inner side wall deposited catalytic layer (conventional reforming catalyst) thickness of 3.5m tortuosity of 3.0. The reactor pressure in both zones is 1 ATM. The limiting stage of the process in such a reactor is the transport of oxygen through the membrane. It is determined by the thickness of the dense layer of perovskite and the rate of dissociation of oxygen on the surface of the first layer of the media. Nitrogen does not pass through the membrane, therefore, in the reaction zone is not formed NOx. In optimal conditions it is possible to achieve selectivity WITH up to 80% conversion of methane to 95%, the temperature in the membrane tube does not exceed 860oC. the Conversion of methane managed to get to level 98% with selectivity OVER 90%, using ceramic membrane containing strategiestable oxides Sr1Fe1Co0,5Ox[U. Balachandran et al. Ceramic membrane reactor for converting methane to syngas.//Catalysis Today, 36, 1997, p.265-272]. The measured flux of oxygen under conditions of catalytic partial oxidation of methane ranges from 0.005 cm3/cm2/s Additional cooling of the operating zone of the membrane reactor is not benefits of the second oxygen supply along the length of the pipe is possible to remove the "hot spot" at the entrance to the membrane reactor.

The disadvantage of this type of reactor is its poor performance in the synthesis gas because of the low feed rate of oxygen ions in the reaction zone and large dimensions. For example, for the conversion of 1680103m3methane requires the reactor 40000 pipe length of 6 m each. A separate problem is the mechanical strength of the ceramic pipes, which often crack under operational conditions.

A device that uses a flame to produce synthesis gas, selected as a prototype, proposed in the application France 2608581, 01 3/00, 24.06.1988). The device is a reactor comprising at least two parts: in the first device - reaction zone 1 - exercise ardent (homogeneous) combustion of methane with oxygen deficiency; the second device in the porous wall of the reaction zone 2 - carry out catalytic additional oxidation of methane. The first device is a conventional methane burner. Combustion of methane with a lack of oxygen (O2/C is 1.5) in the combustion zone temperature above 1500oWith with the cracking of methane to form carbon black. To eliminate soot formation proposed second device zirconium or its oxide. Oxygen (air), and water vapor in a reaction zone to produce distributed through a porous wall along the gas flow stream. In the application proposed other options (figures 3-10) feeding an oxidant into the porous wall. The prototype has several disadvantages. Due to the homogeneous combustion of methane, the temperature in the reaction zone 1 above 1500oWith, therefore you need a reliable insulation of the combustion chamber. Gas and oxidant in the second zone is carried out separately, and the oxidant is supplied by diffusion. This imposes constraints on the production of synthesis gas. To eliminate carbon deposits required to enter except oxidant water vapor. The conversion of methane actually carry on stoichiometry: 1,5 O2served in the first zone and 0.5 O2second. In this embodiment, the process of combustion of methane gives the maximum of the products of complete oxidation (see equation (5)).

The task, which directed the present invention is to remedy these disadvantages.

Achievable technical result is to increase the efficiency of the catalytic conversion of methane into synthesis gas.

This technical result is achieved by the fact that the catalytic reactor rodinnou on one side of the gas distribution tube with a layer of catalyst, having perforations with a diameter less critical, and is equipped with a divider of the jets.

The reactor has an electric heating device to run the reactor. The catalyst is made in the form of a gas-permeable flat and corrugated reinforced tapes, wound and fused with the gas distribution tube, with a gap between the coils with the formation of gas channels between the strips. The catalyst is a reinforced porous material containing as active components, rhodium, Nickel, platinum, palladium, iron, cobalt, rhenium and ruthenium.

The proposed reactor synthesis gas (Fig.1) is a cylindrical structure within which is located the gas distribution device representing one perforated pipe 1, choked on the one hand, inside which is the gas-air mixture. The catalyst layer - 2 is formed from a flat - 4 and corrugated - 3 reinforced mesh gas-permeable tape wound around a distribution tube and sintered with it. Tapes are arranged so that their odd rows Gavrilovna, and even consist of not flat corrugated ribbons, but turns subsequent coils overlap the previous one. Tape obrazuyetsya carbon and water, through the channels between the strips are removed in the environment. Nitrogen oxides are not formed due to the low (~900oC) temperature and lack of oxygen. The catalytic layer with the ends closed by the flanges 5. The heat transfer from the surface of the catalytic layer in the external volume is carried out by convection and infrared radiation. The thickness of the catalytic layer provides complete conversion of methane at the time of contact is not greater than 0.3 sec. To start the reactor in the gas distribution tube mounted heating device 6. The power of the heating device (electric or flame) to about 500 watts.

In Fig.2 shows the section a-a in Fig.1.

The principle of operation of the described reactor following. Include warm-up of the reactor and the temperature inside the unit rises to 600-700oWith, then the heating is turned off. Pre-prepared gas mixture with excess air coefficient of 0.47 relative to the stoichiometric served inside the gas distribution tube 1, resulting in oxidation reactions. The temperature in the catalytic layer adjacent to the gas tube, rises to ~900oWith, and closer to the outer surface layer is reduced to 750-850oC. accounts For the ine pipe, emerging through the holes. For security reasons, the operation of the diameter of the holes is chosen less critical to prevent possible flame inside the gas distribution tube. To suppress the speed of the streams flowing through the perforation hole, around the gas tube is the divider of the jet. In the simplest case, the divider can be a metal mesh or perforated shell. After divider air-gas mixture enters the catalyst bed.

Catalysts for natural gas combustion are reinforced porous material, as active components use the applied rhodium, Nickel, platinum, palladium, iron, cobalt, rhenium and ruthenium. The heat generated in the oxidation reaction in the catalyst bed, entrained in the environment of the reaction products.

Distinctive features of the technical solutions in relation to the prototype are: - reactor synthesis gas production reactor is of the radial type with premixing of gas and oxidant, providing a distributed feed gas mixture along the length of the device; - the reactor to produce synthesis gas contains gazoraspredelitel in the reactor to produce synthesis gas made in the form of gas-permeable flat and corrugated reinforced tapes, wound and fused with the gas distribution tube, with a gap between the coils with the formation of gas channels between the strips;
reactor to produce synthesis gas has a heating device to run in the operating mode;
reactor to produce synthesis gas has a gas distribution device to the diameter of the perforation holes, smaller critical diameter, to prevent penetration of a flame inside the gas distribution tube and divider jets flowing out of the holes of the perforation;
- catalysts for natural gas combustion are reinforced porous material containing as active components, rhodium, Nickel, platinum, palladium, iron, cobalt, rhenium and ruthenium.

Example 1. The synthetic gas generator has the dimensions:
the diameter of 118 mm
- length - 180 mm
- the thickness of the layer of catalyst - 35-37 mm

The synthetic gas generator serves 300 cm3/natural gas composition: (in about. %) CH4=96,03; C2=1,09; C3=1,34; C4=0,44; other gases = 1,10 and 1350 cm3/from the air.

As a result of implementation of catalytic oxidation of natural gas will receive:
the surface temperature of the catalytic layer in contact with the gas distribution tube - 980o- the content of NOx- 0;
- methane - 0,013;
- the CO2- 3,9%;
- the content of N2- 59,5;
- the content of N2On - 2,39.

The conversion of methane to 99.9%, the selectivity for CO - 77%, N2- 90%. The differential pressure during the movement of the gas mixture - 21 mm H2O.

As follows from the above example, the present invention can be used in devices for production of synthesis gas for further use it in methanol synthesis, Fischer-Tropsch, fuel cells, heating and hot water systems for generating heat.


Claims

1. Catalytic reactor radial type to obtain a synthesis gas containing a layer of a catalyst, characterized in that it contains plugged on one side of the gas distribution tube with a layer of catalyst having a perforation diameter less than critical, and is equipped with a divider of the jets.

2. The catalytic reactor under item 1, characterized in that it has an electric heating device to run the reactor in operation.

3. The catalytic reactor under item 1 or 2, characterized in that the catalyst is made in the form of a gas-permeable flat and corrugated reinforced tapes, channels between the strips.

4. The catalytic reactor according to any one of paragraphs.1-3, characterized in that the catalyst is a reinforced porous material containing as active components, rhodium, Nickel, platinum, palladium, iron, cobalt, rhenium and ruthenium.

 

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Reactor // 2246345

FIELD: chemical industry, catalytic processes.

SUBSTANCE: the invention presents a reactor for catalytic processes and is dealt with the field of chemical industry and may be used for catalytic processes. The reactor contains: a body; units of input and output for a reaction mixture and products of reactions; units of loading and unloading of a catalyst; a catalyst layer with the groups of the parallel hollow gas-permeable chambers located on it in height in one or several horizontal planes and each of the chambers has a perforated gas-distributing pipe with impenetrable butt connected to the group collector and used for input of additional amount of the reaction mixture. Each of perforated gas-permeable chambers is supplied with the second gas-distributing pipe with impenetrable butt. At that the impenetrable butts of the pipes are located on the opposite sides. The given engineering solution provides uniformity and entirety of agitation of the reaction mixtures.

EFFECT: the invention provides uniformity and entirety of agitation of the reaction mixtures.

5 cl, 4 dwg

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