EP1051252A1

EP1051252A1 - Catalyst for converting paraffinic hydrocarbon into corresponding olefin

Info

Publication number: EP1051252A1
Application number: EP98964370A
Authority: EP
Inventors: Mordechay Herskowitz; Shimshon Kogan
Original assignee: Mannesmann AG; KTI Group BV
Current assignee: Vodafone GmbH; Technip Holding Benelux BV
Priority date: 1997-12-10
Filing date: 1998-11-23
Publication date: 2000-11-15
Also published as: JP2001525246A; WO1999029420A1; DE19756292C2; AU1959899A; DE19756292A1; KR20010032982A; US6414209B1

Abstract

The invention relates to a calcinated catalyst for converting paraffinic hydrocarbon into corresponding olefin through dehydrogenation. The catalyst is an oxidic, heat-stable carrier material and contains a catalytic active constituent, which is applied on the carrier material and has the following composition (in wt. % in relation to the entire weight of the catalyst): a) 0.2 to 2.0 % of at least one element of the groups Pt and Ir and, acting as a promoter, a combination of elements from the six following groups of substances: b) 0.2 to 5.0 % of at least one of the following elements Ge, Sn, Pb, Ga, In, Tl; c) 0.1 to 5.0 % of at least one of the following elements Li, Na, K, Rb, Cs, Fr; d) 02. to 5.0 % of at least one of the following elements Fe, Co, Ni, Pd; e) 1.0 to 5.0 % P; f) 0.2 to 5 % of at least one of the following elements Be, Mg, Ca, Sr, Ba, Ra and lanthanides and g) 0.1 to 2 % Cl.

Description

"Catalyst for converting paraffinic hydrocarbons into corresponding olefins"

The invention relates to a calcined catalyst for converting paraffinic hydrocarbons into corresponding olefins by dehydrogenation, the

Catalyst has an oxidic, thermally stabilized support material on which the catalytically active component is applied. The invention further relates to a process for converting paraffinic hydrocarbons into corresponding olefins by mixing a stream of the paraffinic hydrocarbons with water vapor and bringing them into contact with a catalyst. The under the

Paraffins to be treated according to the invention are in the range C ₂ to C ₂₀ , preferably in the range C ₂ to C ₅ .

A large number of catalysts are known which are used for the dehydrogenation of paraffins. Such catalysts have a thermally stabilized inorganic oxide as support material, an active component (preferably a platinum group metal) and one or more promoters. Active Al ₂ 0 ₃ is often used as the carrier material, which has a particularly large specific surface.

US Pat. No. 4,788,371 describes a catalyst and a process for the dehydrogenation of paraffins in a water vapor atmosphere. The carrier of the catalyst consists of Al ₂ 0 ₃ and is coated with a noble metal (preferably platinum) and some promoters which are selected from group III or IV of the periodic table and from the subgroup gallium or germanium

(preferably tin) and alkali metals (preferably potassium or cesium). The dehydrogenation process described in this document can operate in the presence of a limited amount of oxygen which is used to heat the reaction zone by burning hydrogen. From US 5 220 091 a catalyst and a process for the dehydrogenation of C ₂ to C ₈ paraffins in the presence of water vapor are known. The catalyst used here consists of platinum (about 0.7% by weight) and zinc and calcium aluminate. In the dehydrogenation of isobutane, a conversion rate of 50% and a selectivity of 94 mol% were achieved, the pressure at P = 3.5 bar, which

Temperature to T = 571 ° C and the ratio of steam to isobutane (mol) was set to 3.96. After a cycle time of 7 hours, the catalyst had to be subjected to a reactivation treatment by oxidative regeneration.

Another method and a catalyst for the dehydrogenation of organic

Compounds are described in EP 0 568 303 A2. This process works with a hydrogen atmosphere. The catalyst contains nickel and various promoters from groups I to VIII of the periodic system on a non-acidic carrier material (base-treated Al ₂ 0 ₃ , zeolites, etc.). The special feature of the technology described in this document is a large number of dehydrogenation zones with intermediate zones for the oxidation of hydrogen generated on a special catalyst. The best results were obtained in the dehydrogenation of isobutane with a nickel catalyst (3.4% Ni and 3.4% Cr on a Ba-exchanged zeolite L), with a temperature of T = 602 ° C, a molar ratio H ₂ / iC ₄ = 6 and a space velocity of GHSV = 650 h ^{"1 were} set

Operating time of 6 hours, the conversion rate was 30 to 36.6% and the selectivity 75.1 to 83.4%. With an operating time of 50 to 65 hours, the conversion rate was in the range from 22.2 to 27.9% and the selectivity in the range from 78.8 to 81.1%.

Another catalyst and a process for the dehydrogenation of hydrocarbons is known from WO 94/29021. The process works in a water vapor-hydrogen atmosphere using a platinum catalyst which contains elements of the tin subgroup and alkali metals (potassium, cesium) as promoters. The peculiarity of the catalyst is a special carrier material, which consists of a mixture of magnesium and aluminum oxide. This composition requires a special pretreatment of the catalyst, which consists in a reduction with hydrogen, caination in a 0 ₂ atmosphere and a further reduction (ROR treatment). With this ROR treatment, the catalyst has a three times higher activity than without this treatment. The Dehydrogenation of propane with the aid of the catalyst described resulted in a temperature of T = 600 ° C., a pressure of P = 1 bar, a space velocity WHSV = 1, 3 h ^"1 and a ratio of H ₂ / H ₂ 0 / C ₃ = 0, 14/1, 2/1 and an operating time of 25 h to the following results: The yield of propylene was 55.5 mol% and the selectivity 96.1 mol%

Comparative experiment with a catalyst known from US Pat. No. 4,788,371 led to a propylene yield of 25.7 to 29.7 mol% and a selectivity of 95.0 to 95.9 mol% under otherwise identical conditions. In this respect, WO 94/29021 represents the previous level of performance in the field of catalytic conversion of paraffinic hydrocarbons into corresponding olefins.

The object of the present invention is to provide a catalyst for converting paraffinic hydrocarbons into corresponding olefins which not only ensures high effectiveness, ie has a good conversion rate and good selectivity, but also high

Shows operational stability, i.e. can be used over comparatively long cycle times before it has to be subjected to a reactivation treatment. The preparation of the catalyst should be as simple as possible. In addition, a process for converting paraffinic hydrocarbons into corresponding olefins is to be specified which leads to good yields of olefins and can be operated over the longest possible cycle times before a catalyst reactivation has to take place.

This object is achieved with regard to the catalyst by the features specified in claim 1 and with respect to the method by the features in claim

16 specified characteristics. Advantageous embodiments of the invention are characterized in the subclaims.

In the course of the investigations which led to the present invention, it was found that catalysts known per se on Al ₂ O ₃ supports, the platinum

Have metal of the germanium or gallium group (preferably tin or indium) and an alkali metal (preferably potassium or cesium), can be significantly improved in terms of their activity by adding certain promoters. In addition to the progress in increasing the catalytic activity, it should be noted as a particular advantage of the invention that none of the specifics in the preparation of the catalyst Activation treatment such as ROR treatment is necessary. In addition, it is not necessary to add hydrogen to the feed when using the catalyst. Rather, the catalyst works very reliably in the presence of oxygen. The catalyst can be prepared by known methods on customary support materials.

The calcined catalyst according to the invention consists of a thermally stabilized support material to which a catalytically active component is applied. The carrier material is preferably aluminum oxide, in particular in the form of Al-Al ₂ 0 ₃ . The catalytically active component consists of the substance groups a) to g) explained in more detail below, the amounts given being in% by weight and based on the total catalyst weight.

The substance group a) comprises the elements Pt and Ir, which represent the catalytically active substance in the narrower sense, while the other substance groups essentially as

Promoters are to be considered which promote catalytic activity. The catalyst must have at least one of the elements of group a), in an amount of 0.2 to 2%. The element Pt is particularly preferred. It is advisable to limit the content of the element or elements of substance group a) to 0.3 to 0.6%.

At least one of each of the elements specified in the substance groups b) to g) described below is represented as a promoter in the catalyst according to the invention. Substance group b) consists of the elements Ge, Sn, Pb, Ga, In and Tl. The content of substance group b) in the catalyst is in the range from 0.2 to 5%, advantageously in the range from 0.5 to 2.5 %. The is particularly preferred

Use of Sn.

Substance group c) comprises the elements Li, Na, K, Rb, Cs and Fr and has a proportion of 0.1 to 5%, preferably 0.5 to 1.5%. The elements K and Cs from this group of substances have proven to be particularly effective.

Substance group d) comprises the elements Fe, Co, Ni and Pd. Their content is in the range from 0.2 to 5%, preferably in the range from 1.0 to 3%. The use of Fe and / or Ni from this group of substances is particularly expedient. As a further promoter, the catalyst according to the invention has a proportion (e) of P on the order of 1.0 to 5%. It is advisable to limit the P content to 2.0 to 4.0%. The substance group f), the amount of which is limited to a proportion of 0.2 to 5%, preferably in a range of 1.0 to 3%, comprises the elements Be, Mg, Ca, Sr, Ba, Ra and the group of Lanthanides. From this group, the elements Ca and Ba are preferred.

Finally, the catalyst has a proportion (g) in the order of 0.1 to 2% of Cl. The element Cl is a component which does not in itself act as a promoter in the strict sense of the word, but which improves the initial dispersion of the noble metal in the catalyst. On the other hand, Cl promotes undesirable side reactions at the beginning of the use of the catalyst. Therefore, the initial salary should be limited significantly.

The present invention also makes a method of converting paraffinic

Proposed hydrocarbons in corresponding olefins, in which a stream of paraffinic hydrocarbons is mixed with water vapor and is brought into contact with a catalyst at a temperature in the range from 500 to 650 ° C. and a pressure of at least 1.0 bar (absolute), which has the composition described above. The addition of H ₂ to the stream of paraffinic hydrocarbons and water vapor, which has been customary to date in many cases, is expediently dispensed with. It is recommended that the molar ratio of water vapor to the paraffinic hydrocarbons be in a range from 0.5: 1 to max. 10: 1, preferably in a range from 1: 1 to 6: 1. The use of the catalyst according to the invention has proven to be particularly advantageous in the case of feedstocks which contain hydrocarbons from the group of the C ₂ to C ₆ paraffins. To improve the reaction, it is advantageous to add 0 ₂ to the stream of paraffinic hydrocarbons, since the oxygen reacts with the released hydrogen and thus shifts the reaction equilibrium. A molar ratio of the paraffinic hydrocarbons to O ₂ in the range from 1: 0.2 to 1: 1.5, in particular in the range from 1: 0.3 to 1: 0.7, has proven to be particularly expedient.

The invention is explained in more detail below on the basis of exemplary embodiments. example 1

To produce a catalyst, 14 g of Al-Al ₂ 0 ₃ as support material (specific surface 130 m ² / g) were impregnated with an aqueous solution of two salts. This solution was formed from 15 cm ^{3 of} water, into which 2.5 g of calcium nitrate ( Tetrahydrate) and 0.7 g of nickel nitrate (hexahydrate). The impregnated support material remained at room temperature for 10 hours and was then dried at 100 ° C. for 5 hours and at 150 ° C. for a further 5 hours The material was then calcined at 350 ° C for 2 hours and at 550 ° C for a further 2 hours, the rate of temperature rise being about 1 ° C / min

The material produced in this way was then impregnated with orthophosphoric acid (55 g of 84% phosphoric acid in 18 cm ^{3 of} water). The material was then dried and calcined again in the manner described above. The material was then treated with tin dichloro (0, 29 g of SnCI ₂ x 2

H ₂ 0 in 20 cm ³ of ethanol with addition of 0.2 g of concentrated hydrochloric acid at warming to stirred up to 40 ^C C constantly) was impregnated, dried and calcined again as described above

This material was then treated with 18 cm ^{3 of} an aqueous solution of

Hexachloroplatinic acid (0.093 g metallic Pt) impregnated, dried and calcined again in the same way. Finally, the material was impregnated with 18 cm ^{3 of} an aqueous solution which contained 0.36 g KN0 ₃ , dried and again calcined in the manner described in this way a catalyst was produced which, based on the total catalyst weight in% by weight, follows

Had composition

3% approx

1% Ni

1% P

2% Sn

1% K

0.6% Pt

0.5% Cl - 1 -

This catalyst is shown as Catalyst A in Table 1.

Example 2

The effectiveness of Catalyst A was tested in an experiment that lasted 5 hours and in which propane was dehydrated in a steam atmosphere. The following values were set as test conditions:

P = 1 bar

T = 550 ° C

WHSV = 1, 2 h ^"1

H ₂ 0 / C ₃ = 4.5 (mol)

The resulting conversion rate, the selectivity and the propane yield are shown in Table 1.

Example 3

In a corresponding form, as described in Example 1, catalysts B, C, D and E were produced, with only the P content being increased in stages to 2.0% (B), 2.5% (C), 3, 5% (D) or 5.0% (E) was increased. The composition of the catalysts B to E is given in Table 1. Likewise, in this

Table shows the results obtained in an activity test of these catalysts, the test conditions being the same as in Example 2.

Example 4

For comparison with the catalysts A to E according to the invention, a catalyst F was again prepared analogously to the manner described in Example 1, but neither P nor Ca was added to the composition. This catalyst was also tested under the conditions given in Example 2. The results are shown in Table 1.

Example 5

As a second comparative example, a catalyst G was produced analogously to the manner described in example 1, which had the composition of catalyst B with the exception that no Ni was present. This catalyst G was again tested under the test conditions of Example 2. The results are shown in Table 1.

Example 6 A catalyst H was prepared analogously to the manner described, the

The composition of the catalyst D differed in that the K content was increased to 1.5% and the P content to 3%, and in addition 3.5% Fe was added instead of 1% Ni. The Fe addition took place in the form of an aqueous solution of Fe (N0 ₃ ) ₃ × 9H ₂ 0. This catalyst was again tested under the conditions of Example 2. The results are shown in Table 1.

Example 7

A catalyst K was produced in a manner analogous to that described, the composition of which essentially differed from that of catalyst H only in that 1% Pd was added instead of 3.5% Fe. The

Palladium was added in the form of an aqueous solution of PdCl ₂ , which contained 3% HCl. The effectiveness was again tested under the conditions of Example 2. The results are shown in Table 1.

Example 8

A catalyst L was produced in a manner analogous to that described, which differed from catalyst D only in that the P content was reduced from 3.5% to 3.0% and 3% Ce was added instead of 3% Ca. . This catalyst was also tested again under the conditions of Example 2. The results are shown in Table 1.

Example 9

A catalyst M was produced in the same way as catalyst B, only the content of K being increased from 1% to 2.2%. This catalyst was also tested under the conditions of Example 2. The results are shown in Table 1.

Example 10 A catalyst N was produced in the same way as catalyst D, but the content of P was reduced from 3.5% to 3% and instead of 1% K here

2% Cs was added. The catalyst was again tested under the conditions of Example 2. The results are shown in Table 1.

Example 11

A catalyst R was produced in the same way as catalyst B, the composition differing only from the composition of catalyst B in that 2% Ba was added instead of 3% Ca.

The barium was added as a nitrate in aqueous solution. The catalyst was again tested under the conditions of Example 2. The results are shown in Table 1.

Example 12

Again for comparison with the catalysts according to the invention, a catalyst S was produced in the manner described in Example 1, but the elements Ni, Ca and P were left out of the composition. This catalyst was again tested under the conditions of Example 2. The results are shown in Table 1.

From Table 1 it is clearly evident that the addition of Ca, Ni and P to platinum-tin-potassium catalysts known per se brings about a very considerable increase in the catalyst activity in relation to the dehydrogenation of paraffins in a steam environment. This is shown by the catalysts A to E according to the invention, for example in

Comparison to the comparative catalyst S. This is a completely unexpected effect for the person skilled in the art, because the addition of only one of these components (namely Ni) or only two of these components (namely Ca and P) have a negative influence on the catalyst efficiency, like this show the two catalysts F and G not according to the invention in comparison to the catalyst S likewise not according to the invention. It should also be borne in mind that it is generally known that P is a catalyst poison in catalytic dehydrogenation using a noble metal catalyst. In the case of catalysts H and K, Table 1 shows that the promoter effect is also ensured if, instead of Ni, another metal from the iron group (Group VIII), which is considered a catalyst poison in relation to platinum, or Palladium is used. The example of catalysts L and R shows that another alkaline earth metal (eg barium) or a rare earth metal (eg cerium) can be used instead of calcium.

Example 13

To check their long-term effectiveness, the catalysts B, L and S were subjected to an operating test in which the same conditions as in Example 2 were set. Only the duration of the experiment was extended significantly. The results are shown in Table 2. With the comparative catalyst S, the test had to be stopped after about 20 hours of operation due to coking.

Example 14

Catalysts B and D were also subjected to a long-term test in the dehydrogenation of propane. In contrast to the test conditions of the example

13, however, the following parameter values were set:

P = 2 bar

T = 580 ° C WHSV = 1, 2 h ^"1

H ₂ 0 / C ₃ = 6 (mol).

For catalyst B, the ratio H ₂ 0 / C _{3 was set} to 4 (mol) instead of 6 (mol). The results of the two tests are shown in Table 3.

Example 15

Catalyst B was tested in a test in which isobutane was dehydrated under the following conditions over a test period of 5 hours:

P = 1 bar

T = 530 to 550 ° C

WHSV = 1, 2 h ^'1 H ₂ 0 / iC ₄ = 4 (mol). The results are shown in Table 4.

The advantages of the catalysts according to the invention are clearly confirmed by the results of the long-term tests shown in Tables 2 and 3. The improved activity and selectivity is also evident in the dehydrogenation of other paraffins such as isobutane. The test results shown in Table 4 confirm that the catalyst effectiveness in the dehydrogenation of olefins is ensured both in a pure water vapor environment and when oxygen is added (lower half of the measurement results in Table 4). Compared to the known catalysts described at the outset, the catalyst according to the invention also shows a clearly better activity over a longer operating period, so that the cycle time between two reactivation treatments is considerably longer.

Claims

claims

1. Calcined catalyst for converting paraffinic hydrocarbons into corresponding olefins by dehydrogenation, the catalyst being an oxidic, thermally stabilized support material and a catalytically active one

Contains component, which is applied to the support material and has the following composition (in wt .-% of the total catalyst weight): a) 0.2 to 2.0% of at least one of the elements of the group Pt and Ir, and as a promoter a combination of elements from each of the following six groups of substances: b) 0.2 to 5.0% of at least one of the elements Ge, Sn, Pb, Ga, In, Tl, c) 0.1 to 5.0% of at least one of the elements Li, Na , K, Rb, Cs, Fr, d) 0.2 to 5.0% of at least one of the elements Fe, Co, Ni, Pd, e) 1.0 to 5.0% P, f) 0.2 to 5 % of at least one of the elements Be, Mg, Ca, Sr, Ba, Ra and the lanthanides, g) 0.1 to 2% Cl.

2. Catalyst according to claim 1, characterized in that the carrier material is Al ₂ 0 ₃ , in particular Θ-Al ₂ 0 ₃ .

3. Catalyst according to one of claims 1 to 2, characterized in that the content of the elements of group a) is limited to 0.3 to 0.6%.

4. Catalyst according to one of claims 1 to 3; characterized in that the content of the elements from substance group b) is limited to 0.5 to 2.5%.

5. Catalyst according to one of claims 1 to 4; characterized in that the content of the elements from group c) is limited to 0.5 to 1.5%.

Catalyst according to one of claims 1 to 5; characterized in that the content of the elements from substance group d) is limited to 1.0 to 3.0%.

7. Catalyst according to one of claims 1 to 6; characterized in that the P content is limited to 2.0 to 4.0%.

8. Catalyst according to one of claims 1 to 7; characterized in that the content of the elements from group f) is limited to 1.0 to 3.0%.

9. Catalyst according to one of claims 1 to 8; characterized in that Pt is selected as an element from group a).

10. Catalyst according to one of claims 1 to 9; characterized in that Sn is selected as an element from group b).

1 1. Catalyst according to one of claims 1 to 10; characterized in that K is selected as an element from group c).

12. Catalyst according to one of claims 1 to 1 1; characterized in that Cs is selected as an element from group c).

13. A catalyst according to any one of claims 1 to 12; characterized in that Fe and / or Ni is selected as an element from group d). Catalyst according to one of claims 1 to 13, characterized in that Ca is selected as an element from group f)

Catalyst according to one of claims 1 to 14, characterized in that Ba is selected as an element from group f)

Process for converting paraffinic hydrocarbons into corresponding olefins, in which a stream of paraffinic

Hydrocarbons mixed with water vapor and brought into contact with a catalyst according to one of Claims 1 to 15 at a temperature in the range from 500 to 650 ° C and a pressure of at least 1.0 bar (absolute)

A method according to claim 16, characterized in that the stream of paraffinic hydrocarbons and the water vapor are free

Method according to one of claims 16 to 17, characterized in that the molar ratio of the water vapor to the paraffinic hydrocarbons is at least 0.5 1

Method according to one of claims 16 to 18, characterized in that the molar ratio of the water vapor to the paraffinic hydrocarbons is limited to a maximum of 10 1

Process according to claims 18 and 19, characterized in that the molar ratio of the water vapor to the paraffinic hydrocarbons is in the range from 1 1 to 6 1

21. The method according to any one of claims 16 to 20, characterized in that the hydrocarbons belong to the group of C _{2 to} C ₆ paraffins.

22. The method according to any one of claims 16 to 21, characterized in that O _{2 is added to} the stream of paraffinic hydrocarbons.

23. The method according to claim 22, characterized in that the molar ratio of the paraffinic hydrocarbons to O _{2 is} in the range from 1: 0.2 to 1: 1.5.

24. The method according to claim 23, characterized in that the molar ratio of the paraffinic hydrocarbons to O _{2 is} in the range from 1: 0.3 to 1: 0.7.