JP2006522063A - Process for producing at least one partial oxidation product and / or partial ammoxidation product of hydrocarbon - Google Patents

Abstract

In the process for producing at least one partial oxidation product and / or partial ammoxidation product of a hydrocarbon, at least one saturated hydrocarbon (K) is partially dehydrogenated with a heterogeneous catalyst, The resulting product gas mixture (A) containing the partially dehydrogenated hydrocarbon (K) itself or in a modified form of the partially dehydrogenated hydrocarbon contained in the product gas mixture (A). Used for partial oxidation and / or partial ammoxidation with a heterogeneous catalyst, with a mechanical separation operation between the product gas mixture (A) and partial oxidation and / or partial ammoxidation with a heterogeneous catalyst. Is the method.

Description

  In the production of at least one partial oxidation product and / or partial ammoxidation product of a hydrocarbon, the present invention involves subjecting at least one saturated hydrocarbon K to dehydrogenation with a heterogeneous catalyst in the gas phase, In this case, a product gas mixture A containing at least one partially dehydrogenated hydrocarbon K is produced, and saturated hydrocarbon K and partially dehydrogenated hydrocarbon K contained in this product gas mixture A Causes the different constituents to remain in the mixture or to partly or completely separate them to obtain a product gas mixture A 'and to produce the product gas mixture A and / or product gas mixture A' as a gas mixture At least one heterogeneously catalyzed part of at least one partially dehydrogenated hydrocarbon K contained in product gas mixture A and / or product gas mixture A ′ as a constituent of B It relates to a method of subjecting the oxidation and / or partial ammoxidation.

  In the present specification, dehydrogenation with a heterogeneous catalyst is desirably understood as dehydrogenation that proceeds endothermically and generates hydrogen as a major byproduct. This dehydrogenation is carried out in a solid catalyst that reduces the activation energy required for thermal cleavage of C—H bonds. This heterogeneous catalyst dehydrogenation differs from oxidative dehydrogenation by a heterogeneous catalyst in that the latter is forced by the oxygen present and water is formed as a major byproduct. Furthermore, oxidative dehydrogenation with a heterogeneous catalyst proceeds exothermically.

Desirably, the complete oxidation of a hydrocarbon is understood as the conversion of all the carbon contained in the hydrocarbon into an oxide of carbon (CO, CO ₂ ).

  The reaction with oxygen deviating from this complete oxidation is partial oxidation, and in the presence of ammonia, partial ammoxidation.

The methods described at the beginning are known (for example DE-A 10219686, DE-A 10246119, DE-A 10245585, DE-A 10219685, EP-A 731077, DE-A 3131573, DE-A 1031297, DE-A A10211275, EP-A117146, GB-A2118939, U.S. Pat. No. 4,532,365, U.S. Pat. No. 3,161,670 and EP-A193310) and in particular of acrolein, acrylic acid and / or acrylonitrile from propane. A production method, a production method of methacrolein, methacrylic acid and / or methacrylonitrile from isobutane is used. In this case, partial ammoxidation differs from partial oxidation mainly in that ammonia is present in the reaction gas mixture. Further, by suitably selecting the ratio of NH ₃ and O ₂ , partial oxidation and partial ammoxidation can be performed in parallel, that is, simultaneously. By adding an inert diluent gas, the partial oxidation and / or partial ammoxidation reaction gas mixture is kept outside the explosion range.

  In this case (especially in accordance with the teachings of DE-A 3331573, EP-A 117146, GB-A 2118939, US-A 4532365 and US-A 3161670) the product gas mixture A itself and / or the product gas mixture A ' At least one partial oxidation and / or partial oxidation of at least one partially dehydrogenated hydrocarbon K contained in the product gas mixture A and / or the product gas mixture A ′ as a constituent of B Can be subjected to ammoxidation.

  The transition of the product gas mixture A to the product gas mixture A ′ can be carried out most simply by partial or complete separation of the water vapor optionally contained in the product gas mixture A. This can be done, for example, by cooling the product gas mixture and partially or completely condensing the water vapor optionally contained therein.

Naturally, however, the product gas mixture A ′ can also be obtained by separating the other constituents contained in the product gas mixture A. For example, the product gas mixture A is generally configured in a cylinder, is permeable only to hydrogen contained in the product gas mixture A, and thus partially or completely contains hydrogen contained in the product gas mixture A. It may lead to a membrane that separates into The CO ₂ contained in the product gas mixture A can be separated by introducing the product gas mixture A into a liquid alkaline solution. An alternative separation method is adsorption / desorption (stripping) according to DE-A 10245585.

  However, the disadvantages of the prior art method are that for the product gas mixture A, the product gas mixture A ′, and the gas mixture B, before at least one partial or partial ammoxidation with a heterogeneous catalyst, The solid particles contained in the gas mixture are not subjected to a mechanical separation operation that can be separated from the gas mixture. If adsorptive separation methods are used, the adsorbent saturates over time, possibly with solid particles. For example, in the case of stripping and / or desorption, solid particles may entrain.

  Surprisingly, this is, as confirmed by the applicant in a long-term test, that, in the method described at the outset, among the solid catalysts used for dehydrogenation with heterogeneous catalysts, Fine particles can be transported to subsequent partial oxidation and / or ammoxidation with heterogeneous catalysts, which are disadvantageous in that they are optionally deposited in the catalyst fixed bed used there.

  This is disadvantageous in that partial oxidation and / or ammoxidation with a heterogeneous catalyst is usually carried out in the presence of excess oxygen relative to the reaction stoichiometry.

However, also in the presence of oxygen, suitable catalysts for dehydrogenation with heterogeneous catalysts are typically complete combustion of hydrocarbons to CO ₂ and H ₂ O (see, for example, US Pat. No. 4,788,371) and H _It also catalyzes the squeal reaction of ₂ and O ₂ to H ₂ O. Both of these undesirably lead to undesired consumption of reactants in the partial and / or ammoxidation with heterogeneous catalysts (which at the same time undesirably generate additional heat. ), Or it is disadvantageous in that there is a risk that is only evaluated as difficult.

  The object of the present invention is therefore in particular for safe continuous operation over a relatively long period of time (the catalyst lifetime for partial oxidation and / or ammoxidation with heterogeneous catalysts is generally several years). Is also to provide a preferred and advantageous method.

  Accordingly, in the production of at least one partial oxidation product and / or partial ammoxidation product of a hydrocarbon, at least one saturated hydrocarbon K is dehydrogenated by a heterogeneous catalyst in the gas phase. To produce a product gas mixture A containing at least one partially dehydrogenated hydrocarbon K, saturated hydrocarbons K and partially dehydrogenated hydrocarbons contained in this product gas mixture A. The constituents different from K remain in the mixture or are partly or completely separated to obtain a product gas mixture A 'and product gas mixture A and / or product gas mixture A' At least one heterogeneous contact of at least one partially dehydrogenated hydrocarbon K contained in the product gas mixture A and / or product gas mixture A ′ as a constituent of the gas mixture B In the process of partial oxidation and / or ammoxidation by means of the product gas mixture A, product gas mixture A ′ and / or gas mixture B prior to at least one partial oxidation and / or ammoxidation with a heterogeneous catalyst. The present inventors have found a method characterized by subjecting the solid particles contained in the gas mixture to a mechanical separation operation capable of separating the solid particles from the gas mixture.

  The process according to the invention is particularly advantageous in the process of partial oxidation and / or partial ammoxidation with heterogeneous catalysts, generally contained in this mixture from the product gas mixture A itself and / or from the product gas mixture A. The product gas mixture A ′ obtained by partially or completely condensing the steam produced is used.

  Suitable gas purification apparatuses according to the present invention used for the mechanical separation operation are, for example, a sedimentation chamber type separator, a collision type separator and a centrifuge using mass force. However, a sonic separator can also be used in the method according to the present invention. A gas cyclone is also preferred. However, according to the present invention, filtration may be performed simply as a mechanical separation operation. As the filter layer, filter cloth, porous filter material, fleece paper or metal filter medium moistened with oil can be considered. Moreover, according to this invention, an electrostatic sorter can be used. It is also simple to separate the very fine solid particles contained in the gas mixture before the gas mixture reaches the catalyst for partial oxidation and / or partial ammoxidation with the heterogeneous catalyst. May be allowed to flow through an inert fixed bed. In this specification, the concept of mechanical separation operation refers to the extraction of solid particles contained in a gas by exposing the gas to a liquid droplet (eg, a high boiling point organic liquid or water) in direct current or countercurrent. It is desirable to include a spraying device that can The spray liquid is changed after several recirculations to avoid saturation with solid particles.

  Also, according to the present invention, various mechanical separation operations connected in series can naturally be used.

  According to the invention, the dehydrogenation of saturated hydrocarbons K (especially in the case of propane and / or isobutane) with heterogeneous catalysis is generally carried out according to DE-A 3313973, WO 01/96270, DE-A 1013297 or DE. -Can be carried out as described in A102111275.

Since the dehydrogenation reaction using a heterogeneous catalyst proceeds while the volume increases, the conversion can be increased by reducing the partial pressure of the product. This can easily be achieved, for example, by dehydrogenation at reduced pressure and / or by mixing with an inert diluent gas, for example water vapor, which is usually an inert gas for dehydrogenation reactions. In general, dilution with steam provides another advantage of reducing the coking of the catalyst used. This is because the steam reacts with the formed coke by the principle of coal gasification. Furthermore, water vapor can be used in combination as a diluent gas in at least one subsequent oxidation zone and / or ammoxidation zone. However, the water vapor can also be easily separated from the partially or completely dehydrogenated product mixture A (for example by condensation), which means that the product mixture A ′ obtained in this process is at least once partially oxidized. And / or the possibility of increasing the proportion of the dilution gas N ₂ for further use in partial ammoxidation. Another diluent suitable dehydrogenation heterogeneous catalyst, for example CO, methane, ethane, CO _2, nitrogen and noble gases, such as He, Ne and Ar. All known diluents can be used together either alone or in the form of various mixtures. This is also based on the advantage that the abovementioned diluents are generally suitable diluents in at least one partial oxidation and / or partial ammoxidation. The inert diluent is a diluent that behaves particularly inert in each reaction (ie, chemically changes to less than 5 mol%, preferably less than 3 mol%, more particularly preferably less than 1 mol%). is there. For dehydrogenation with heterogeneous catalysts, in principle all dehydrogenation catalysts known in the prior art are conceivable. These can be roughly divided into two groups. That is, an oxidic group (eg, chromium oxide and / or aluminum oxide) and at least one generally relatively valuable metal (eg, platinum, palladium, generally deposited on an oxide support). (Tin, gold, silver).

  That is, according to the present invention, WO01 / 96270, EP-A731077, DE-A10211275, DE-A10131297, WO99 / 46039, US-A4788371, EP-A0705136, WO99 / 29420, US-A4220091 All types of dehydrogenation catalysts recommended in US Pat. No. 5,430,220, US Pat. No. 5,877,369, EP-A-0117146, DE-A 1937196, DE-A 19937105 and DE-A 19937107 can be used. In particular, the catalysts according to DE-A 19937107, Examples 1, 2, 3, and 4 can be used.

  In this case, 10 to 99.9% by mass of zirconium dioxide, 0 to 60% by mass of aluminum oxide, silicon dioxide and / or titanium dioxide, and 0.1 to 10% by mass of at least one element in the periodic table of elements Elements of the first main group or the second main group, elements of at least one third subgroup of the periodic table of elements, elements of at least one eighth subgroup of the periodic table of elements, lanthanum and / or Or the dehydrogenation catalyst which contains tin but the sum total of the mass percentage becomes 100 mass% is mentioned.

  In order to carry out the dehydrogenation with a heterogeneous catalyst according to the invention, in principle all reactor types and variants known in the prior art are conceivable. Descriptions of such variants are included in all prior art references cited for example with respect to dehydrogenation catalysts.

Relatively detailed description of the preferred dehydrogenation process according to the present invention also provides, "Catalytica ^(R) Research Division, selective dehydrogenation and oxidative dehydrogenation, research number 4192OD, 1993 years, 430, Ferguson Drive, Mountain view, CA, 94043-5272 United States of America ^{"(Catalytica (R) Studies Division} , Oxidative Dehydrogenation and Alternative Dehydrogenation Processes, Study Number 4192OD, 1993, 430 Ferguson Drive, Mountain view, California, 94043-5272 USA) are also included in the Yes.

  A feature of partial dehydrogenation of saturated hydrocarbons with heterogeneous catalysts is that this proceeds endothermically. That is, either the heat (energy) required for adjusting the required reaction temperature is supplied to the reaction gas starting mixture in advance and / or during the course of dehydrogenation with a heterogeneous catalyst. Must be done.

  Furthermore, for the dehydrogenation of saturated hydrocarbons such as propane and isobutane with heterogeneous catalysts, the required reaction temperature is high, so that high-boiling high molecular weight organic compounds or carbons are formed in a small amount, which is the catalyst surface. It is common to deposit on top and thereby deactivate the catalyst. In order to minimize this disadvantageous entrainment phenomenon, a reaction gas mixture containing saturated hydrocarbons K to be led to the catalyst surface and dehydrogenated when the temperature is increased for dehydrogenation with a heterogeneous catalyst. May be diluted with water vapor. The precipitated carbon is partially or completely removed under the conditions given in this way by the principle of coal gasification.

  Another possibility to remove the precipitated carbon compound is to let the dehydrogenation catalyst flow through with an oxygen-containing gas, sometimes at an elevated temperature, thereby almost burning out the deposited carbon compound. However, also sufficiently suppressing the formation of carbon deposits leads to a saturated hydrocarbon K (eg propane or isobutane) to be dehydrogenated by the heterogeneous catalyst, leading to a dehydrogenation catalyst by raising the temperature. It is also possible by adding molecular hydrogen before.

  Of course, there is also the possibility of adding steam and molecular hydrogen in a mixture to the saturated hydrocarbon K to be dehydrogenated with a heterogeneous catalyst. The addition of molecular hydrogen for the propane heterogeneous catalyzed dehydrogenation also reduces the unwanted formation of allene (propadiene), propyne and acetylene as by-products.

  A reactor configuration suitable for dehydrogenation with a heterogeneous catalyst according to the present invention is a fixed bed tube reactor or a tube bundle reactor. That is, the dehydrogenation catalyst is present in one reaction tube or one bundle of reaction tubes as a fixed bed. The reaction tube is heated by burning a gas, for example a hydrocarbon such as methane, in a space surrounding the reaction tube. Advantageously, this direct heating mode of the catalyst tube is only applied to the first about 20% to about 30% of the fixed bed layer, and the remaining length layers are freed within the combustion range. Heating up to the required reaction temperature. In this way, a reaction operation at almost isothermal temperature can be achieved. A suitable reaction tube inner diameter is from about 10 cm to about 15 cm. A typical dehydrogenation tube bundle reactor has 300 to 1000 reaction tubes. The temperature inside the reaction tube varies within a range of 300 to 700 ° C, preferably within a range of 400 to 700 ° C. Advantageously, the reaction gas starting mixture is preheated to the reaction temperature and fed to the tubular reactor. It is possible for the product gas mixture to leave the reaction tube at a temperature as low as 50-100 ° C. However, the outlet temperature may also be higher or at an equivalent level. Within the scope of the process, the use of oxide dehydrogenation catalysts based on chromium oxide and / or aluminum oxide is suitable. Often, rather than using a diluting gas in combination, the starting reaction gas starts primarily from saturated hydrocarbons K (eg, propane or crude propane) only. The dehydrogenation catalyst is also used with little dilution.

  On a large scale industry, multiple (for example, three) such tube bundle reactors can be operated in parallel. In this case, according to the invention, in some cases, the two reactors are in dehydrogenation operation, while the catalyst charge is regenerated in the third reactor, but in at least one partial zone. Will not be damaged.

  Such a method is suitable, for example, in the case of the Linde propane dehydrogenation method known in the literature. However, it is significant according to the invention that it is sufficient to use one such tube bundle reactor.

Such a method is also described in Phillips Petroleum Co. It can be used in the so-called “steam active reforming (STAR) method” developed by the company (see, for example, US Pat. No. 4,902,849, US Pat. No. 4,996,387 and US Pat. No. 5,389,342). As a dehydrogenation catalyst, the STAR process preferably uses platinum containing a cocatalyst on a zinc (magnesium) spinel as support (see, for example, US Pat. No. 5,073,662). Unlike the BASF-Linde propane dehydrogenation method, in the case of the STAR method, the propane to be dehydrogenated is diluted with steam. The molar ratio of water vapor to propane is generally in the range of 4-6. The reactor outlet pressure is often 3-8 atm and the reactor temperature is suitably selected at 480-620 ° C. Typical catalyst loadings for all reaction gas mixtures are 0.5-10 h ⁻¹ (LHSV).

  Dehydrogenation with the heterogeneous catalyst according to the invention can also be carried out in a moving bed. The catalyst moving bed may be housed, for example, in a radial flow reactor. Within this reactor, the catalyst moves slowly from top to bottom while the reaction gas mixture flows radially. This method is used, for example, in the so-called UOP-Oleflex dehydrogenation process. In the case of this method, the reactor is operated semi-adiabatically, and accordingly, a plurality of reactors are suitably connected in cascade and operated (generally up to four reactors). As a result, it is possible to avoid the temperature difference between the reaction gas mixture at the reactor inlet and the reaction gas mixture at the reactor outlet from becoming too large. And the reduction of the reaction temperature depends on its heat capacity), nevertheless an adequate total conversion can be achieved.

When the catalyst bed leaves the moving bed reactor, it is fed to the regenerator and then used again. For this method, for example, a spherical dehydrogenation catalyst composed mainly of platinum on a spherical aluminum oxide support can be used as the dehydrogenation catalyst. In the case of the UOP variant, hydrogen is added to the saturated hydrocarbon K (eg propane) to be dehydrogenated to avoid premature alteration of the catalyst. The working pressure is generally 2-5 atm. In the case of propane, the (molar) ratio of hydrogen to propane is suitably 0.1-1. The reaction temperature is preferably 550 to 650 ° C., and contact time of the reaction gas mixture with the catalyst is selected from about ^{2h -1} ~ about ^{6h -1.}

  In the case of the fixed bed method described above, the catalyst geometry is also spherical, but may also be configured in a cylindrical shape (hollow or solid) or other geometric shapes.

  Another variant for the heterogeneously catalyzed dehydrogenation of saturated hydrocarbons K is Dewitt Bulletin, Petrochemical Research, Houston, Texas, 1992a, N1 (Proceedings De Witt, Petrochem. Review, Houston, Texas , 1992a, N1) describe the possibility of dehydrogenation with a heterogeneous catalyst in a moving bed that does not dilute hydrocarbons.

  According to the present invention, in this case, for example, two moving beds can be operated simultaneously, one of which can be temporarily present in a regenerated state without adversely affecting the entire process. In this case, chromium oxide on aluminum oxide is used as the active substance. The working pressure is generally 1-2 atm and the dehydrogenation temperature is generally 550-600 ° C. The heat required for dehydrogenation is introduced into the reaction system through preheating the dehydrogenation catalyst to the reaction temperature. Said dehydrogenation is also known in the literature as the Snamprogeti-Yarsintez method.

  Apart from the above method, a dehydrogenation catalyst with a heterogeneous catalyst under sufficient oxygen exclusion can also be realized by a method developed by ABB Lummus Crest (Dewit Bulletin, Petrochemical Research, Houston, Texas, 1992). Year, P1 (see Proceedings De Witt, Petrochem. Review, Houston, Texas, 1992, P1).

  Conventionally described methods for dehydrogenating saturated hydrocarbons K with heterogeneous catalysis under sufficient oxygen exclusion are those with ≧ 30 mol% (generally ≦ 60 mol%) of saturated hydrocarbons K (for example, It is common to operate at (propane) conversion (for one reaction zone pass). According to the present invention, it is advantageous to achieve a saturated hydrocarbon K (eg propane) conversion of ≧ 5 mol% to ≦ 30 mol% or ≦ 25 mol%. That is, dehydrogenation with a heterogeneous catalyst can be operated at a conversion rate of 10 to 20 mol% (the conversion rate relates to one reaction zone passage). In particular, the residual amount of unreacted saturated hydrocarbon K (eg propane) functions mainly as an inert diluent gas in at least one subsequent partial oxidation and / or partial ammoxidation, which It is based on being able to return to the dehydrogenation zone and / or at least one zone without loss.

  In order to achieve the conversion mentioned above, it is advantageous to carry out the dehydrogenation with a heterogeneous catalyst, generally at a working pressure of 0.3-3 atm. Furthermore, it is advantageous to dilute the saturated hydrocarbon K to be dehydrogenated with the heterogeneous catalyst with steam. Thus, on the one hand, the heat capacity of water can offset part of the endothermic effect of dehydrogenation, and on the other hand, dilution with steam can reduce the starting and product partial pressures, which It works favorably on the elementary equilibrium situation. Further, the combined use of water vapor as described above has an advantageous effect on the useful life of the dehydrogenation catalyst containing the noble metal. Moreover, you may add molecular hydrogen as another component as needed. In this case, the molar ratio of molecular hydrogen to saturated hydrocarbon K (eg propane) is generally ≦ 5. Accordingly, the molar ratio of water vapor to saturated hydrocarbon K at a relatively low hydrocarbon K conversion may be ≧ 0-30, suitably 0.1-2, preferably 0.5-1. . Also, the low dehydrogenation conversion method is advantageous because only a relatively small amount of heat is carried when the reaction gas passes through the reactor once, and the conversion rate is achieved during one pass through the reactor. A relatively low reaction temperature is sufficient to do this.

  It may therefore be appropriate to carry out the dehydrogenation with a relatively low conversion (quasi) adiabatically. That is, the reaction gas starting mixture is generally first heated to a temperature of 500-700 ° C. (or 550-650 ° C.) (eg, by directly heating the inner wall surrounding it). Then, it is usually sufficient to pass the catalyst bed once adiabatically to achieve the desired conversion, with the reaction gas mixture (depending on conversion and dilution) at about 30 ° C. Decrease by ~ 200 ° C. The presence of water vapor as a heating medium is also significantly advantageous from the viewpoint of adiabaticity. The low reaction temperature increases the useful life of the catalyst bed used.

  In principle, dehydrogenation with a heterogeneous catalyst with a relatively low conversion rate, whether carried out adiabatically or isothermally, is carried out in a fixed bed reactor and moving bed reactor or fluidized bed reactor. Can be implemented within.

  Significantly, in the case of the process according to the invention, for the realization thereof, in particular in adiabatic operation, a single upright furnace as a fixed bed reactor through which the reaction gas mixture flows axially and / or radially. A type reactor is sufficient.

  In this case, the simplest is a single sealed reaction volume, for example an inner diameter of 0.1-10 m, optionally also 0.5-5 m, in which the catalyst fixed bed is a support device (for example , Grid). The reaction volume loaded with the catalyst shuts off heat in an adiabatic operation, with the hot reaction gas containing saturated hydrocarbons K flowing through in the axial direction. In this case, the catalyst geometry may be spherical as well as ring or strand. In this case, all catalyst geometries with particularly low pressure losses should be preferred, since the reaction volume should be realized with very inexpensive equipment. This is in particular a catalyst geometry that results in a large hollow chamber volume or is structurally constructed, such as a monolith or honeycomb. For the realization of the radial flow of the reaction gas containing saturated hydrocarbons K, the reactor consists of two cylindrical grids, for example present in the jacket, arranged concentrically with each other, A catalyst layer may be provided in the annular gap. In the case of an adiabatic type, it may be desirable in some cases to block the heat in the same manner.

  Suitable catalysts for the dehydrogenation with heterogeneous catalysts with a relatively low conversion in one pass are in particular those known from DE-A 19937107, in particular those known in all examples.

After a long operating time, the catalyst is supplied with, for example, 300-600 ° C., often 400-550 ° C. inlet temperature, first (preferably) diluted air with nitrogen and / or hydrogen in the first regeneration stage. It is possible to reproduce easily by introducing it. In this case, the catalyst filling amount with the regeneration gas is, for example, 50 to 10,000 h ⁻¹ , and the oxygen content of the regeneration gas is 0.5 to 20% by volume.

In a subsequent further regeneration stage, air can be used as regeneration gas under otherwise similar regeneration conditions. Of course, for industrial applications, it is desirable to clean the catalyst with an inert gas (eg, N ₂ ) prior to its regeneration.

  Then, generally using more pure molecular hydrogen or molecular hydrogen diluted with an inert gas (preferably water vapor) (hydrogen content is preferably ≧ 1% by volume), the others It is desirable to reproduce within a range of equivalent conditions.

Dehydrogenation with a heterogeneous catalyst with a relatively low conversion (≦ 30 mol%) is, in all cases, a catalyst loading equivalent to the variant with a high conversion (> 30 mol%) (all the reaction gases as well as this (Saturated hydrocarbon K contained in the reaction gas). The filling amount of the reaction gas, for example 100～10000H ^-1, often 300～5000H ^-1, in particular often be about 500h ^-1 ~ about 3000h ^-1.

  Particularly suitably, the dehydrogenation with a heterogeneous catalyst with a relatively low conversion can be carried out in a shelf reactor.

  The reactor has one or more catalyst beds that catalyze dehydrogenation in spatial succession. The number of catalyst beds may be 1-20, suitably 2-8, but may also be 3-6. This catalyst bed is preferably provided continuously in the radial or axial direction. For industrial applications, it is appropriate to use a fixed catalyst bed type in such a shelf reactor.

  Most simply, the fixed catalyst bed is provided axially in an upright reactor or in an annular gap of a cylindrical grid arranged concentrically with each other. However, it is also possible to provide an annular gap above and below the compartment and direct gas into the next compartment above or below it after it has flowed out radially in one compartment.

  Suitably, the reaction gas mixture is routed from one catalyst bed to the next, for example, on heat exchanger fins heated with hot gas, or with tubes heated with hot combustion gas. To the intermediate heating in a shelf reactor.

  In other respects, when the shelf reactor is operated adiabatically, the desired conversion (≦ 30 mol%), especially when using the catalyst described in DE-A 19937107, in particular the exemplary embodiment For this purpose, it is sufficient to preheat the reaction gas mixture to a temperature of 450-550 ° C., lead it into the dehydrogenation reactor and maintain it in this temperature range in the shelf reactor. That is, it is clear that all dehydrogenation can be carried out at such very low temperatures, which is particularly advantageous for the lifetime of the fixed catalyst bed between the two regeneration stages.

  More suitably, the intermediate heating is carried out directly (self-heating). For this purpose, molecular oxygen is added to the reaction gas mixture in a limited amount, either before the first catalyst bed and / or before the subsequent catalyst bed. Therefore, depending on the dehydrogenation catalyst used, the process of dehydrogenation with the hydrocarbons contained in the reaction gas mixture, possibly with the char or carbonaceous compounds already deposited on the catalyst surface, and / or the heterogeneous catalyst Limited combustion of hydrogen formed in and / or hydrogen added to the reaction gas mixture occurs (and, for industrial applications, hydrogen combustion (and / or hydrocarbon combustion) is specifically (selected) In particular, it is appropriate to insert a catalyst bed into a shelf reactor loaded with the catalyst to be catalyzed (for example, such as US Pat. No. 4,788,371, US Pat. No. 4,886,928, US Pat. No. 5,430,209). US Pat. No. 5,530,171, US Pat. No. 5,527,979 and US Pat. No. 5,563,314 are conceivable; for example, such a catalyst bed contains a dehydrogenation catalyst. That may be housed in a tray reactor alternately to the floor)). Therefore, dehydrogenation by a heterogeneous catalyst can be operated almost isothermally by the reaction heat liberated at that time. Therefore, the greater the selective residence time of the reaction gas in the catalyst bed, the more dehydrogenation can be achieved at a lower temperature or mainly at a constant temperature, in particular, thereby extending the useful life between the two regeneration stages. Can do.

In general, it is desirable to supply oxygen as described above so that the oxygen content of the reaction gas mixture is 0.5 to 30% by volume with respect to the amount of saturated hydrocarbon K contained therein. . In this case, the oxygen source can be pure molecular oxygen or oxygen diluted with an inert gas such as CO, CO ₂ , N _{2 or} a noble gas, in particular air. The resulting combustion gas generally has a further diluting effect and this promotes dehydrogenation with heterogeneous catalysts.

  The isothermal nature of the dehydrogenation with heterogeneous catalysts can be achieved in a shelf reactor, in a space between the catalyst beds, sealed internal structures that have been evacuated, which is advantageous but not necessary before filling them (e.g. Further improvement can be achieved by providing a tube shape. Such internal structures may also be located in each catalyst bed. This internal structure has suitable solids or fluids, which evaporate or melt at a temperature above a predetermined temperature, in which case heat is consumed and condenses again when below this temperature, in which case Releases heat.

The possibility of heating the reaction gas starting mixture to the reaction temperature required for the dehydrogenation with a heterogeneous catalyst also allows some of the saturated hydrocarbons K and / or H ₂ contained in this mixture to be molecular. The desired reaction temperature is obtained by burning with oxygen (for example by transferring and / or passing once, for example, to a suitable combustion catalyst which acts specifically) and with the heat of combustion thus released. It is to cause heating up to. The resulting combustion products, such as CO ₂ , H ₂ O, and optionally N ₂ with the molecular oxygen required for combustion, advantageously form an inert diluent gas.

Particularly suitably, the hydrogen combustion can be realized as described in DE-A 10211275. That is, in the partial dehydrogenation by the continuous heterogeneous catalyst of the saturated hydrocarbon K in the gas phase,
The reaction zone is continuously fed with a reaction gas containing saturated hydrocarbons K to be dehydrogenated,
The reaction gas in the reaction zone is led to at least one catalyst fixed bed in which molecular hydrogen and at least partially dehydrogenated hydrocarbons K are formed by dehydrogenation with the catalyst,
-Before and / or after the reaction gas is introduced into the reaction zone, to which is added a gas containing at least molecular oxygen,
-Molecular oxygen in the reaction zone partially oxidizes molecular hydrogen contained in the reaction gas to water vapor, and-From the reaction zone, molecular hydrogen, water vapor, partially dehydrogenated hydrocarbons K and ( A partial dehydrogenation process for removing a product gas containing saturated hydrocarbons K) to be dehydrogenated, wherein the product gas taken from the reaction zone is divided into two partial quantities of the same composition, and both partial quantities A partial dehydrogenation process characterized in that one of them is returned to the dehydrogenation reaction zone as circulating gas and the other partial quantity is further used as product gas mixture A according to the invention.

  Furthermore, the above-described variant of the catalytic dehydrogenation to be used according to the invention can be used in particular when the saturated hydrocarbon K to be dehydrogenated is propane and / or isobutane.

  By the way, the product gas mixture A and / or the product gas mixture A ′ that can be produced from the mixture as described above are used for partial oxidation and / or partial ammoxidation by a heterogeneous catalyst as known per se. It may be used to load mixture B (see prior art listed first). What is important in the present invention is that the product gas mixture A, the product gas mixture A ′ and / or the mixture B are contained in this gas mixture before at least one partial oxidation and / or partial ammoxidation with a heterogeneous catalyst. It is only subjected to a mechanical separation operation in which the solid particles contained in can be separated from this gas mixture.

  As partial oxidation, for the process according to the invention, in particular, partial oxidation from propene (obtained by partial dehydrogenation of propane) to acrolein and / or acrylic acid and isobutene (obtained by partial dehydrogenation of isobutane). ) To methacrolein and / or methacrylic acid.

  As partial ammoxidation, in particular for the process according to the invention, partial ammoxidation from propene to acrylonitrile and partial ammoxidation from isobutene to methacrylonitrile can be considered.

Example 1. On the outer and inner surfaces of the dehydrogenation catalyst ZrO ₂ · SiO ₂ mixed oxide support (strands in the range of 3-8 mm in length, 2 mm in diameter; produced according to Example 3 of DE-A 102 19879), DE- A Pt / Sn alloy with the promoter added with the elements Cs, K and La in oxide form was applied as described in A10219879. The stoichiometric composition (mass ratio) of this element was: Pt _0.3 Sn _0.6 La _3.0 Cs _0.5 K _0.2 (ZrO ₂ ) _88.3 (SiO ₂ ) _7.1 .

  The application of the promoter-added alloy as described above is carried out by impregnating the ground support with the corresponding metal salt solution and then heat-treating it at 560 ° C. (1.5 hours) in a stream of air. did. In the range of heat treatment, the active components Pt and Sn and the cocatalyst were converted to their oxide form. In the dehydrogenation reactor described later, the active component of the catalyst precursor was reduced to a metal at 500 ° C. in a hydrogen stream as described later to obtain an active catalyst.

2. Dehydrogenation reactor (C330)
650 ml (762 g) of the catalyst precursor obtained as described above was vertically fixed in the following tubular reactor (tube length: 2049 mm, wall thickness: 7 mm, inner diameter: 41 mm, metal: interior coated with aluminum (that is, Steel tube coated with aluminum oxide) (fixed on the catalyst pedestal from bottom to top): 299 mm is steatite ring (outer diameter x length x inner diameter = 7 mm x 3 mm x 4 mm), then 50 mm Steatite spheres with a diameter of 4-5 mm, then 25 mm with a steatite sphere with a diameter of 1.5-2.5 mm, then 500 mm with a catalyst precursor, then 50 mm with a steatite sphere with a diameter of 4-5 mm, then 1080 mm with a steatite ring (Outer diameter x length x inner diameter = 7 mm x 3 mm x 4 mm). As steatite, Fa. Steatite C-220 manufactured by CeramTec was used. Heat the reaction tube to Fa. In a heating coil furnace manufactured by HTM Reetz (reaction tube was introduced in this), four heating zones each extending in length of 2 × 220 cm, each continuously extending from the bottom to the top. Conducted (electrically). There was a gap of about 72.5 mm width between the tube surface and the heating coil. The reaction tube extends from bottom to top up to a length of 1000 mm on its outer wall. It was covered with a microporous heat insulating material having a thickness of 100 mm of Type MPS-Super G manufactured by Mienherm DE (quasi-adiabatic reaction part). In this region, this heating served only as auxiliary heating, while being used to directly heat the tube area in this upper region.

  In order to accommodate a plurality of thermocouples, a thermowell (outer diameter = 6 mm, inner diameter = 4 mm) was inserted in the reaction tube from the top to the bottom with a length of 1.50 m.

  A thermowell having a length of 60 cm was introduced into the reaction tube from the bottom to the top.

  Activation of the catalyst precursor was carried out as described in Example 1 of DE-A 10211275 in a hydrogen stream.

3. Experimental Facility Propane or n-butane (hereinafter, liquefied petroleum gas is referred to as LPG) was used as the hydrocarbon to be dehydrogenated by the heterogeneous catalyst.

There are 4 experimental facilities in total:
-Metering device-Reactor device-Circulating gas device-Discharge device.

  Within the metering device, the liquid starting material LPG and water were introduced into the evaporator W100 (if necessary, in a nitrogen stream) and converted into the gas phase in the evaporator. After the evaporator stage, the gas mixture produced in the evaporator could be mixed with air, molecular oxygen and molecular hydrogen, if necessary, to obtain the desired new starting mixture.

  Within the reactor apparatus, the new starting mixture is heated to a temperature of 400-500 ° C. in a preheater (heat exchanger) W200 (optionally in a mixture with circulating gas) and then the dehydrogenation reaction as described above. Guided into vessel C330 (from top to bottom). At that time, the heating zone showed the following temperatures from below to above: 500 ° C., 550 ° C., 550 ° C., and 550 ° C. The inlet pressure in the dehydrogenation reactor was selected up to 2 bar.

  Product gas mixture A exiting the dehydrogenation reactor was directed to an air cooled heat exchanger and cooled to 300 ° C. The mixture was then transferred completely or partially via a conduit into the discharge and further processed in the discharge. When only a partial amount of the cooled product gas mixture A was introduced into the discharge portion, the remaining partial amount was supplied to the circulating gas device.

  In the same circulating gas apparatus, a part amount of the product gas mixture A circulated and guided is first further cooled to 150 ° C. in the heat exchanger W420 operated by the heat medium oil, and then in the compressor V440. This was recompressed to 2 bar and then transferred to a heat exchanger W460 heated to 300 ° C. before it was integrated with the new starting gas mixture before the preheater W200 stage (then fed to the preheater) did).

4). Results The experimental facility was operated primarily continuously over a period of 3 months. A total of 26 reaction cycles were performed. After each reaction cycle, regeneration of the dehydrogenation catalyst was carried out according to DE-A 10028582 in the order of washing, combustion, washing and reduction. Within the reaction cycle (the minimum duration of the reaction cycle was 3 hours and the maximum duration of the reaction cycle was 100 hours), the conditions were kept constant. The conditions for all cycles are in the following ranges:
Hydrocarbon: LPG;
Cycle time: 3 to 100 hours;
LPG amount: 500-2000 g / h;
New water vapor: 500-1000 g / h;
Nitrogen: 0-50 NI / h;
Air: 0-375 NI / h;
Hydrogen: 0 to 150 NI / h;
Heating zone temperature: 500 ° C, 550 ° C, 550 ° C, 550 ° C;
Inlet pressure: 2 bar Circulating gas ratio: 0 or 5 (ratio of circulating volume to outflow volume).

  The part of the experimental facility that was exposed to temperatures below 300 ° C. was made from V2A steel. The part of the laboratory facility that was exposed to temperatures above 300 ° C. was made from 1.4841 steel.

  After completion of the experimental system, a considerable amount of filmy rust was observed in all parts of the experimental facility that were flowed through by the circulating gas and all product gas mixture A. This was due to the rust of the conduit with condensed water (obviously caused by the precooling of the product gas mixture A).

Analysis of film-like rust by atomic absorption spectrum revealed Zr, Si, and Pt components that can be attributed only to the dehydrogenation catalyst in addition to the expected constituents Fe, Ni, and Cr. This analyzed rust sample has a total amount of the following elements:
Carbon: 1.5 g / 100 g;
Al: 2.2 g / 100 g;
Cr: 2.6 g / 100 g;
Fe: 13.1 g / 100 g;
Mg: 10.6 g / 100 g;
Ni: 1.9 g / 100 g;
Pt: 0.019 g / 100 g;
Si: 20.6 g / 100 g;
Zr: 0.17 g / 100 g
showed that.

  In the analysis of the sample of the product gas mixture A taken out one by one, Zr, Si and Pt could not be detected. Obviously, the amount they contain is below the detection limit.

Claims (5)

  In producing at least one partial oxidation product and / or partial ammoxidation product of a hydrocarbon, at least one saturated hydrocarbon K is subjected to dehydrogenation with a heterogeneous catalyst in the gas phase, wherein at least A product gas mixture A containing one kind of partially dehydrogenated hydrocarbon K is produced, and the constituents different from the saturated hydrocarbon K and the partially dehydrogenated hydrocarbon K contained in this product gas mixture A In the mixture or partially or completely separated to obtain the product gas mixture A ′ and the product gas mixture A and / or the product gas mixture A ′ as constituents of the gas mixture B And at least one heterogeneous catalytic partial oxidation of at least one partially dehydrogenated hydrocarbon K contained in the product gas mixture A and / or product gas mixture A ′ and Or in the process of partial ammoxidation, the product gas mixture A, the product gas mixture A ′ and / or the gas mixture B are subjected to this gas before at least one partial oxidation and / or partial ammoxidation with a heterogeneous catalyst. A method characterized by subjecting the solid particles contained in the mixture to a mechanical separation operation that can be separated from the gas mixture.   The saturated hydrocarbon K is propane, and the partial oxidation of the partially dehydrogenated hydrocarbon K by the heterogeneous catalyst is partial oxidation of propene to acrolein and / or acrylic acid. Item 2. The method according to Item 1.   The saturated hydrocarbon K is isobutane, and the partial oxidation of the partially dehydrogenated hydrocarbon K by the heterogeneous catalyst is partial oxidation of isobutene to methacrolein and / or methacrylic acid, The method of claim 1.   2. The partial ammoxidation of the partially heterohydrogenated hydrocarbon K by the heterogeneous catalyst of the saturated hydrocarbon K is propane and is a partial ammoxidation of propene to acrylonitrile. The method described in 1.   The saturated hydrocarbon K is isobutane, and the partial ammoxidation of the partially dehydrogenated saturated hydrocarbon K by the heterogeneous catalyst is partial ammoxidation from isobutene to methacrylonitrile. The method according to 1.