REACTOR AND METHOD FOR MAXIMIZING METHANOL YIELD BY USING CATALYST LAYERS

Abstract

The invention relates to a reactor for the catalytic production of methanol, in which at least two catalyst layers are arranged. The first catalyst layer is arranged upstream and the second catalyst layer is arranged downstream. The activity of the first catalyst layer is higher than the activity of the second catalyst layer.

Claims

1. Reactor for the catalytic production of methanol, comprising at least two catalyst layers for the production of methanol arranged in the reactor, wherein the first catalyst layer is arranged upstream and the second catalyst layer is arranged downstream, and wherein the activity of the first catalyst layer for the production of methanol is higher than the activity of the second catalyst layer.

2. Reactor according to claim 1, wherein the catalyst layers are arranged directly adjacent to each other.

3. Reactor according to claim 1, wherein the catalyst layers are arranged in a single packed bed filling.

4. Reactor according to claim 1, wherein the at least two catalyst layers have an essentially identical layer thickness.

5. Reactor according to claim 1, wherein further catalyst layers for the production of methanol, are arranged in the reactor, wherein the further catalyst layers are each arranged downstream of the second catalyst layer, and wherein the activity of the further catalyst layers for the production of methanol successively increases towards the downstream end of the reactor.

6. Reactor according to claim 4, wherein further catalyst layers for the production of methanol, are arranged in the reactor, wherein the further catalyst layers are each arranged downstream of the second catalyst layer, and wherein the activity of the further catalyst layers for the production of methanol successively increases towards the downstream end of the reactor.

7. Reactor according to claim 5, wherein the layer thickness of the first catalyst layer is smaller than the layer thickness of the further catalyst layers.

8. Reactor according to claim 7, wherein the layer thickness of the first catalyst layer is 5% to 20%, and wherein the further catalyst layers exhibit a substantially identical layer thickness.

9. Reactor according to claim 8, wherein a total of four catalyst layers are provided, wherein the layer thickness of the first catalyst layer is 10% of the total thickness of all catalyst layers, and wherein the layer thickness of the three further catalyst layers each is about 30% of the total thickness of all catalyst layers.

10. Method for the catalytic production of methanol from synthesis gas, wherein the method comprises the following steps: providing a reactor; arranging at least two catalyst layers for the production of methanol in the reactor, wherein the first catalyst layer is arranged upstream and the second catalyst layer is arranged downstream, and wherein the activity of the first catalyst layer is higher than the activity of the second catalyst layer; applying synthesis gas to the reactor, comprising hydrogen and carbon oxides, converting the synthesis gas in the reactor under methanol synthesis conditions to methanol, channeling the produced methanol and the non-converted synthesis gas out of the reactor.

11. Method according to claim 10, wherein the reactor is a water-cooled reactor and the cooling temperature is between 200 C. and 260 C., preferably between 230 C. 250 C.

12. Method according to claim 10, wherein at least two further catalyst layers for the production of methanol from synthesis gas are arranged in the reactor, wherein the further catalyst layers are each arranged downstream of the second catalyst layer, and wherein the activity of the further catalyst layers successively increases towards the downstream end of the reactor.

13. Method according to claim 10, wherein the cooling temperature and the layer thickness and the activity of the individual catalyst layers is chosen such that the resulting reaction temperature in the reactor does not exceed about 260 C.

14. Reactor according to claim 5 wherein two further catalyst layers for the production of methanol are provided.

15. Reactor according to claim 6 wherein two further catalyst layers for the production of methanol are provided.

16. Reactor according to claim 7 wherein the layer thickness of the first catalyst layer is 10% of the total thickness of all catalyst layers.

17. Method according to claim 11 wherein the cooling temperature is between 230 C. and 250 C.

Description

[0045] The invention will be described in the following with reference to the attached figures by multiple examples in more detail. The figures show:

[0046] FIG. 1 a schematic depiction of an arrangement of two reactors according to the application WO 2011/101081 A1;

[0047] FIG. 2 a schematic basic arrangement of two reactors with one catalyst layer each;

[0048] FIG. 3 an illustrative first arrangement of a reactor with two catalyst layers according to the invention;

[0049] FIG. 4 an illustrative second arrangement of a reactor with four catalyst layers according to the invention; and

[0050] FIG. 5 an exemplarily measurement diagram for comparing the third example with the basic arrangement

BASIC ARRANGEMENT

[0051] The basic arrangement which is provided as a comparative arrangement has been chosen such that it resembles the structure of an arrangement which is typically used in the industry for a methanol synthesis plant, in which two reactors with one catalyst layer each are utilized, and as it is exemplarily described in the application WO 2011/101081 A1. For the specific description of the components which are depicted in FIG. 1, it is thus referred to the description of FIG. 1 in the application WO 2011/101081 A1. In the basic arrangement, two reactors 1 and 2 are utilized. In both reactors, the same catalyst material MegaMax 800 with a pellet size of 64 mm is used. However, in this and the subsequently described examples, random catalyst materials such as copper-based methanol synthesis catalysts can be utilized, as long as the catalyst layers have the desired activity and thickness to prevent or reduce the formation of a hotspot. The first reactor, reactor 1, is configured as a water-cooled reactor (WCRwater cooled reactor), whereas the second reactor, reactor 2, is configured such that it resembles the temperature profile of a gas-cooled reactor (GCRgas cooled reactor), which is known from the prior art. The schematic structure of the basic arrangement is depicted in FIG. 2. In the following tables, the measurement values of this basic arrangement are reproduced in the third column.

[0052] In the following tables, m.sub.catalyst denotes the mass of the used catalyst material. T.sub.cool(first reactor) denotes the temperature of the water mantle in the area of the first catalyst layer. The recycle ratio RR denotes the ratio between fresh and reused, non-converted synthesis gas. GHSV denotes the gas hourly space velocity. T.sub.max denotes the maximum temperature occurring in the catalyst layers during the synthesis reaction. X.sub.CO.sub._.sub.pp(first reactor) denotes the amount of converted carbon monoxide in the first reactor, wherein the first reactor in the examples according to the invention is the reactor in which the catalyst layers according to the invention are arranged. X.sub.CO2.sub._.sub.pp(first reactor) denotes the amount of converted carbon dioxide in the first reactor. X.sub.CO.sub._.sub.pp(all reactors) (ppper pass) denotes the amount of converted carbon monoxide in all reactors in total. X.sub.CO2.sub._.sub.pp(all reactors) denotes the amount of converted carbon dioxide in all reactors in total. STY.sub.(first reactor) denotes the specific product outputs or space-time-yield, i.e. the quantity of product formed in the first reactor per volume and time. STY.sub.(all reactors) denotes correspondingly the specific product output of all reactors. This nomenclature applies also to the following examples according to the invention. Thus, the basic arrangement with two reactors is compared with the arrangement according to the invention of multiple catalyst layers in one reactor.

EXAMPLE 1

[0053] As depicted in FIG. 3, two catalyst layers are provided in the first arrangement in reactor 1 according to the invention. The two catalysts are catalysts of the MegaMax series, particularly MegaMax 800 catalysts, wherein the catalysts have different pellet sizes. Other catalysts can also be utilized such as copper-based methanol synthesis catalysts. The first catalyst layer has a pellet size of 33 mm, wherein the second catalyst layer has a pellet size of 64 mm.

[0054] Synthesis gas travels from the first catalyst layer to the second catalyst layer. The first catalyst layer has a higher activity than the second catalyst layer.

[0055] Additionally, as depicted in FIG. 3, a further reactor 2 is provided, which exhibits only one catalyst layer. This reactor only contains one catalyst with moderate activity (MegaMax 800 with a pellet size of 64 mm). Apart from the provision of two catalyst layers in the water-cooled reactor 1, the structure corresponds to the structure which is depicted in FIG. 2.

[0056] In the following, a comparison of the arrangement according to the first example of the invention (second column) and the basic arrangement (third column) is depicted in tabular form.

TABLE-US-00001 TABLE 1 basic arrangement - 2-layer catalyst 1 catalyst - 2 bed - 2 reactors reactors unit m.sub.catalyst 2.8 2.8 Kg T.sub.cool (first reactor) 230 250 C. recycle ratio 1.6 1.6 GHSV 15000 15000 h.sup.1 T.sub.max 286.4 +/ 2.2 284.0 +/ 2.1 C. X.sub.CO.sub..sub.pp (first reactor) 87.7 +/ 1.2 69.8 +/ 1.2 % X.sub.CO2.sub..sub.pp (first reactor) 30.0 +/ 7.4 15.2 +/ 3.7 % X.sub.CO.sub..sub.pp (all reactors) 90.2 +/ 1.1 86.3 +/ 1.2 % X.sub.CO2.sub..sub.pp (all reactors) 35.0 +/ 3.4 25.0 +/ 6.9 % STY.sub.(first reactor) 2.02 +/ 0.11 1.70 +/ 0.06 kg/(l * h) STY.sub.(all reactors) 0.91 +/ 0.12 0.96 +/ 0.05 kg/(l * h)

[0057] This comparison shows that, by providing 2 catalyst layers in the first reactor as described above, the conversion of carbon monoxide can be increased by about 18% and the conversion of carbon dioxide of about 15%. Also, the specific product output in the first reactor can be increased by about 18%. By the enhanced conversion of carbon oxides in the first reactor, the heat production can furthermore be increased. Although the temperature of the coolant has been reduced in the example, the maximum temperature T.sub.max is increased in comparison to the basic arrangement. The reduced cooling temperature contributes about 8% to the increased conversion of carbon monoxide, since a higher equilibrium conversion occurs at this temperature.

EXAMPLE 2

[0058] FIG. 4 shows a second arrangement according to the invention, in which only one reactor filled with catalyst is provided. This reactor is water-cooled. The arrangement corresponds to the arrangement which is shown in FIG. 2 with the difference that, instead of the two reactors 1 and 2, only the water-cooled reactor 1 is filled with catalyst material, and reactor 2 remains empty. In this reactor 1, four catalyst layers are provided, wherein part of these catalysts are catalysts of the MegaMax series. The layers are configured as a first layer of MegaMax 800 with a pellet size of 64 mm and a relative layer thickness of 10%, in relation to the total thickness of all catalyst layers. The second layer is C79-5 with a pellet size of 55 mm and a relative layer thickness of 30%. The third layer is MegaMax 800 with a pellet size of 64 mm with a relative layer thickness of 30%. The fourth layer is MegaMax 800 with a pellet size of 33 mm with a relative layer thickness of 30%. Also, other catalysts such as copper-based methanol synthesis catalysts can be utilized. The catalysts and pellet sizes are chosen such that the activity of the last catalyst layer is highest. The second layer has the lowest activity.

[0059] As can be seen in the following table 2, the conversion of the carbon oxides and the specific product output in the arrangement according to the invention is enhanced compared to the basic arrangement by about 10% (CO) and 18% (CO.sub.2). Also, due to the increased conversion of carbon oxides, the heat generation in the reactor is increased, which leads to a higher maximum temperature T.sub.max in the catalyst bed. Since only one reactor is used in the arrangement according to the invention, the specific product output of the whole plant is increased by about 115%.

TABLE-US-00002 TABLE 2 Basic 4-layer arrangement - catalyst bed - 1 catalyst - 1 reactor 2 reactors Unit m.sub.catalyst 1.5 2.8 Kg T.sub.cool (first reactor) 250 250 C. recycle ratio 1.6 1.6 GHSV 15000 15000 h.sup.1 T.sub.max 286.2 +/ 1.0 284.0 +/ 2.1 C. X.sub.CO.sub..sub.pp (first reactor) 79.7 +/ 1.0 69.8 +/ 1.2 % X.sub.CO2.sub..sub.pp (first reactor) 33.2 +/ 1.7 15.2 +/ 3.7 % X.sub.CO.sub..sub.pp (all reactors) 86.3 +/ 1.2 % X.sub.CO2.sub..sub.pp (all reactors) 25.0 +/ 6.9 % STY.sub.(first reactor) 2.06 +/ 0.03 1.70 +/ 0.06 kg/(l * h) STY.sub.(all reactors) 0.96 +/ 0.05 kg/(l * h)

EXAMPLE 3

[0060] In the third example, a structural arrangement has been chosen, as is shown in FIG. 4. In comparison to the second example, the synthesis reaction has been conducted at a lower temperature. This leads to a lower deactivation of the catalysts and therefore to a higher yield. It is assumed that the activity of the catalysts after 1000 hours of operation is about 10% higher than the activity of the catalysts in the basic arrangement. As shown in the following table, the conversion of carbon oxides increases in comparison to the basic arrangement by about 13% (CO) and 19% (CO.sub.2), and the specific product output of the reactor by 22%.

TABLE-US-00003 TABLE 3 Basic 4-layer arrangement - catalyst bed - 1 catalyst - 1 reactor 2 reactors Unit m.sub.catalyst 1.5 2.8 Kg T.sub.cool (first reactor) 230 250 C. recycle ratio 1.6 1.6 GHSV 15000 15000 h.sup.1 T.sub.max 260.5 +/ 0.6 284.0 +/ 2.1 C. X.sub.CO.sub..sub.pp (first reactor) 82.4 +/ 0.6 69.8 +/ 1.2 % X.sub.CO2.sub..sub.pp (first reactor) 34.2 +/ 1.2 15.2 +/ 3.7 % X.sub.CO.sub..sub.pp (all reactors) 86.3 +/ 1.2 % X.sub.CO2.sub..sub.pp (all reactors) 25.0 +/ 6.9 % STY.sub.(first reactor) 2.07 +/ 0.04 1.70 +/ 0.06 kg/(l * h) STY.sub.(all reactors) 0.96 +/ 0.05 kg/(l * h)

[0061] FIG. 5 shows the temperature development within the catalyst layers during the synthesis reaction in the basic arrangement and in the arrangement which is shown in FIG. 4 at a lower temperature regime (example 3). By using four catalyst layers, the temperature in the catalyst layers can be reduced, while at the same time the conversion of carbon oxides and the specific product output can be enhanced.

[0062] The above described exemplary embodiments are not to be understood limiting. Other embodiments which are consistent with the above described exemplary embodiments are now sufficiently described for the skilled person.