Abstract
A reactor for the catalytic production of methanol having two or more reaction zones arranged and surrounded by a heat exchange fluid. The reaction zones are preferably reaction tubes, and each reaction zone has at least one cleaning layer and at least one catalyst layer, where the cleaning layer is arranged upstream, and the catalyst layer is arranged downstream. A method for the catalytic production of methanol from synthesis gas using the reactor is also described.
Claims
1. A reactor for the catalytic production of methanol, comprising two or more reaction zones, which are surrounded by a heat exchange fluid, wherein at least one catalyst layer is arranged in each of the two or more reaction zones, wherein at least one cleaning layer, which comprises a cleaning material, is arranged in each of the two or more reaction zones, and wherein the at least one cleaning layer is arranged upstream of the at least one catalyst layer.
2. The reactor of claim 1, wherein at least two catalyst layers that are different from each other are arranged in each of the two or more reaction zones, and wherein, of the at least two catalyst layers, a first catalyst layer is arranged upstream and a further catalyst layer(s) is/are arranged downstream.
3. The reactor of claim 2, wherein an activity of the first catalyst layer is lower than an activity of the further catalyst layer(s).
4. The reactor of claim 1, wherein a layer height of the cleaning layer(s) is 5 to 30% of a total layer height of all catalyst layer(s) and cleaning layer(s) in the reaction zones.
5. The reactor of claim 1, wherein an additional cleaning layer is arranged upstream of the two or more than two reaction zones, and wherein the additional cleaning layer contains cleaning material that is the same as or different from the cleaning material in the two or more reaction zones.
6. The reactor of claim 1, wherein the cleaning material essentially does not contribute to the catalytic production of methanol.
7. The reactor of claim 1, wherein the cleaning material reduces a quantity of contaminants present in a synthesis gas stream introduced into the reactor, wherein the contaminants can poison catalysts in the catalyst layer(s) and are reduced by adsorption, absorption, and/or decomposition.
8. The reactor of claim 1, wherein catalysts in the catalyst layer(s) and/or the cleaning material in the cleaning layer(s) are arranged in the form of fixed packed beds.
9. The reactor of claim 1, wherein the two or more reaction zones are arranged in a heat exchanger reactor, wherein the reaction zones are arranged substantially parallel and/or radial with respect to a central longitudinal axis of the reactor, and wherein the reactor is a water-cooled reactor, an oil-cooled reactor, or a gas-cooled reactor.
10. The reactor of claim 1, wherein the reaction zones are formed as reactor tubes.
11. A method for the catalytic production of methanol from synthesis gas, the method comprising: providing a reactor; arranging two or more reaction zones, selected from reactor tubes or reactor plates, which are surrounded by a heat exchange fluid, in the reactor, charging the reactor with a synthesis gas comprising hydrogen and carbon oxides, converting the synthesis gas in the reactor to methanol under methanol synthesis conditions, and conducting the generated methanol and the unconverted synthesis gas out of the reactor, wherein at least one catalyst layer is arranged in each of the two or more reaction zones, wherein at least one cleaning layer, which comprises a cleaning material, is arranged in each of the two or more reaction zones, and wherein the at least one cleaning layer is arranged upstream of the at least one catalyst layer.
12. The method of claim 11, wherein at least two catalyst layers that are different from each other are arranged in each of the two or more reaction zones, and wherein, of the at least two catalyst layers, a first catalyst layer is arranged upstream and a further catalyst layer(s) is/are arranged downstream.
13. The method of claim 12, wherein an activity of the first catalyst layer is lower than an activity of the further catalyst layer(s).
14. The method of claim 11, wherein the reactor is a water-cooled reactor, and a cooling temperature is in a range of from 180 C. to 270 C.
Description
[0082] The invention is described in more detail below using several examples with reference to the appended figures. The figures show:
[0083] FIG. 1 illustrative first arrangement, not according to the invention, of two reactor tubes without a cleaning layer, with a catalyst layer MM1
[0084] FIG. 2 illustrative second arrangement, according to the invention, of two reactor tubes with a cleaning layer and a catalyst layer MM1
[0085] FIG. 3 illustrative third arrangement, according to the invention, of two reactor tubes with a cleaning layer and two catalyst layers MM1 and MM2
[0086] FIG. 4 example temperature profile for an arrangement, not according to the invention, without a cleaning layer, with a catalyst layer MM1
[0087] FIG. 5 example temperature profile for an arrangement, according to the invention, with a cleaning layer and a catalyst layer MM1, wherein the vertical dashed line symbolizes the boundary between cleaning layer and catalyst layer MM1, and the horizontal dashed line shows the temperature of the heat exchange fluid
[0088] FIG. 6 example temperature profile for an arrangement, according to the invention, with a cleaning layer and two catalyst layers MM1 and MM2, wherein the two vertical dashed lines symbolize the boundaries between cleaning layer and catalyst layer MM1 and between catalyst layer MM1 and catalyst layer MM2, and the horizontal dashed line shows the temperature of the heat exchange fluid
[0089] FIG. 7 example temperature profiles for an arrangement, not according to the invention, without a cleaning layer, with a catalyst layer MM1 for various service lives
[0090] FIG. 8 example temperature profiles for an arrangement, according to the invention, with a cleaning layer and a catalyst layer MM1 for various service lives
[0091] FIG. 9 example temperature profiles for an arrangement, according to the invention, with a cleaning layer and two catalyst layers MM1 and MM2 for various service lives
[0092] FIG. 10 example development of the methanol yield as a function of the service life for an arrangement, according to the invention, with a cleaning layer and a catalyst layer MM1 compared with an arrangement, not according to the invention, with a catalyst layer MM1 but without a cleaning layer, assuming a deactivation slowed by 20% due to the cleaning layer (standardized to the initial methanol yield of the arrangement, not according to the invention, with a catalyst layer MM1 but without a cleaning layer)
[0093] FIG. 11 example development of the methanol yield as a function of the service life for an arrangement, according to the invention, with a cleaning layer and two catalyst layers MM1 and MM2 compared with an arrangement, not according to the invention, with a catalyst layer MM1 but without a cleaning layer, assuming a deactivation slowed by 10% and by 20% due to the cleaning layer (standardized to the initial methanol yield of the arrangement, not according to the invention, with a catalyst layer MM1 but without a cleaning layer)
EXAMPLES
[0094] In the following examples, a copper-based catalyst from the MegaMax series is used in different pellet sizes and referred to as MM1 and MM2, respectively, in the examples and the figures. MM1 has a pellet size of 6 mm4 mm in a cylindrical shape (diameterheight) and MM2 has a pellet size of 3 mm3 mm in a cylindrical shape (diameterheight).
[0095] The test arrangement on which the simulations are based was chosen so that it reflects the setup of an arrangement of a methanol synthesis plant typical in industry. The reactor is formed as a water-cooled reactor (WCR) and synthesis gas flows through it at a space velocity of approx. 14,000 h.sup.1.
[0096] In the following examples and figures, TOS (time-on-stream) furthermore refers to the service life of a catalyst in years, and z is the relative position along the reactor axis in the reactor tubes in the flow direction, assuming a 100% fill, wherein the gas inlet is at z equals 0.0 and the gas outlet is at z equals 1.0. In the figures, the dashed line represents the cooling temperature. The vertical dotted lines illustrate the different plies.
Example 1 (Comparison)
[0097] A water-cooled methanol reactor with a loading of 100 vol.-% of a packed bed of catalyst MM1 without an upstream cleaning layer is used in Example 1. This corresponds to the setup depicted in FIG. 1.
Example 2
[0098] A water-cooled methanol reactor with a loading with two layers (10 vol.-% guard bed, 90 vol.-% packed bed of catalyst MM1) is used in Example 2. This corresponds to the setup depicted in FIG. 2.
Example 3
[0099] A water-cooled methanol reactor with a loading with three layers (10 vol.-% guard bed, 65 vol.-% packed bed of catalyst MM1 and 25 vol.-% packed bed of catalyst MM2) is used in Example 3. This corresponds to the setup depicted in FIG. 3.
Example 4
[0100] FIG. 4 shows a typical temperature profile in the water-cooled methanol reactor according to Example 1 with a cooling temperature of 250 C. as a function of the position along the reactor axis z.
[0101] FIG. 5 shows a typical temperature profile in the water-cooled methanol reactor according to Example 2 with a cooling temperature of 250 C. as a function of the position along the reactor axis z. The guard bed was assumed to be a packed bed of spheres with a diameter of 3 mm that is inert with regard to the methanol production.
[0102] FIG. 6 shows a typical temperature profile in the water-cooled methanol reactor according to Example 3 as a function of the position along the reactor axis z.
[0103] The comparison of FIG. 4 with FIG. 5 shows that the presence of a cleaning layer arranged upstream leads to a significant heating of the entering gas from approx. 225 C. to approx. 238 C., i.e. by approximately 13K. Despite this heating, the hotspot temperature only increases by less than 1K, from approx. 267 C. to approx. 268 C. Through the heating-up of the gas in the guard bed layer (inert for the methanol reaction), the synthesis gas reaches the catalyst at a higher temperature that is advantageous for the activity thereof.
[0104] In FIG. 6, a second hotspot can additionally be seen in the second (more active) catalyst layer. The hotspot is the result of the exothermicity forming due to the additional reaction and occurring due to the higher activity of the second catalyst layer, and thus illustrates a further increase in the yield compared with Example 2 in FIG. 5. The comparison of FIG. 6 with FIG. 5 shows that the presence of a second more active catalyst layer leads to a heating of the gas by approximately 2K, which results from a higher rate of conversion by this catalyst.
Example 5
[0105] FIG. 7 shows typical temperature profiles in the water-cooled methanol reactor according to Example 1 as a function of the position along the reactor axis z for service lives (TOS=time-on-stream) of from 0 to 6 years. The underlying deactivation profile was derived from real plant data. The deactivation proceeds along the reactor axis z over time and is described mathematically using a so-called logistic function. This leads to the displacement of the hotspot, observed in real plants, downstream over the service life.
[0106] FIG. 8 shows typical temperature profiles in the water-cooled methanol reactor according to Example 2 as a function of the position along the reactor axis z for service lives (TOS=time-on-stream) of from 0 to 6 years. The guard bed was assumed in each case to be a packed bed of spheres with a diameter of 3 mm that is inert with regard to the methanol production. The same deactivation behaviour as in FIG. 7 was used as the basis in the simulation (i.e. a reduced ageing to be expected because of the reduction in the quantity of catalyst poisons in the synthesis gas due to the guard bed was not taken into consideration). The simulations therefore reflect a worst case scenario and merely demonstrate the positive influence of the combination according to the invention of guard bed layer and catalyst layering on the temperature profile in the reactor tube over the lifetime.
[0107] The comparison of FIG. 7 and FIG. 8 shows, as already previously, that for one thing the presence of a cleaning layer arranged upstream contributes to a significant heating of the entering gas from approx. 225 C. to approx. 238 C., i.e. by approximately 13K. Despite this heating, the hotspot temperature only increases by less than 1K, from approx. 267 C. to approx. 268 C. Through the heating-up of the gas in the guard bed layer (inert for the methanol reaction), the synthesis gas reaches the catalyst at a higher temperature that is advantageous for the activity thereof.
[0108] In FIG. 9, a second hotspot can again be seen in the second (more active) catalyst layer. The comparison of FIG. 9 with FIG. 8 shows that the presence of the second catalyst layer with a more active catalyst still leads, for example in the case of a service life of 2 years, to a significant heating of the gas by approximately 3K, because of a higher rate of conversion by the more active catalyst.
Example 6
[0109] FIG. 10 shows the relative methanol yield in percent as a function of the service life for an arrangement according to the invention with two layers according to Example 2 (10 vol.-% guard bed and 90 vol.-% of a packed bed of catalyst MM1) compared with an arrangement not according to the invention without an upstream cleaning layer according to Example 1 (100 vol.-% packed bed of catalyst MM1). The values are standardized to the methanol yield of a 100 vol.-% packed bed of catalyst MM1 at the time point 0 years. A deactivation reduced by 20% because of the reduction in the quantity of catalyst poisons in the synthesis gas due to the cleaning material in the guard bed was assumed in the simulations for the arrangement according to the invention. FIG. 10 shows a slower decline in the methanol yield for the arrangement according to the invention. This difference between the reactor according to the invention and a conventional reactor arises in particular from an operating time of 4 years, from which a much higher methanol yield manifests itself.
Example 7
[0110] FIG. 11 shows the relative methanol yield in percent as a function of the service life for an arrangement according to the invention with three layers according to Example 3 (10 vol.-% guard bed, 65 vol.-% packed bed of catalyst MM1 and 25 vol.-% packed bed of catalyst MM2) compared with an arrangement not according to the invention without an upstream cleaning layer according to Example 1 (100 vol.-% packed bed of catalyst MM1). The values are standardized to the methanol yield of a 100 vol.-% packed bed of catalyst MM1 at the time point 0 years. A deactivation reduced by 10% and another reduced by 20% because of the reduction in the quantity of catalyst poisons in the synthesis gas due to the cleaning material in the guard bed was assumed in the simulations for the arrangement according to the invention. FIG. 11 shows that an initial yield of methanol identical to the comparison example is achieved through the arrangement of catalyst layers with different activity levels, although only 90% of the reactor is filled with catalyst (this therefore corresponds to a higher space-time yield), with a cleaning layer being introduced at the same time. From the beginning and over the entire lifetime, the slower decline in the methanol yield for the arrangement according to the invention leads to a higher methanol yield compared with an arrangement not according to the invention.
[0111] The above-described example embodiments are not to be understood as limitative. Other embodiments which are consistent with the above-described example embodiments are now described in an obvious manner for a person skilled in the art.
