RU2803505C2 - Paraffin dehydrogenation catalyst - Google Patents

Abstract

FIELD: catalysts.

SUBSTANCE: group of inventions relates to a paraffin dehydrogenation catalyst with a modified carrier to increase crushing strength, as well as to a method for its production. A method for producing a paraffin dehydrogenation catalyst having increased crush strength is presented, comprising the following: (a) obtaining a rare earth-modified alumina carrier in the form eta-alumina containing a compound containing a rare earth element; (b) impregnating the rare earth-modified alumina carrier with a chromium-containing solution to form a second carrier; (c) drying the second carrier to obtain a third carrier; (d) calcining the third carrier to obtain a paraffin dehydrogenation catalyst; wherein the paraffin dehydrogenation catalyst has a crushing strength of more than about 0.4 daN/mm, and the paraffin dehydrogenation catalyst comprises a rare earth metal oxide in the range of 0.5-5 wt.%, chromium oxide in the range of 17-40 wt.%, at least one alkali metal component in the range of 0.1-5 wt.%, eta-alumina the rest, and at least one alkali metal component comprises a compound of sodium, potassium, rubidium, or combinations thereof, and obtaining in stage (a) includes the following: (e) receiving eta-alumina media; (f) impregnating the eta-alumina carrier with a solution containing a rare earth compound to obtain a first carrier; and (g) drying the first carrier and calcining the dried first carrier to obtain a rare earth-modified alumina carrier in the form of eta-alumina. In another embodiment, a paraffin dehydrogenation catalyst is provided comprising: a carrier containing eta-alumina; from 0.1 to 10 wt.% of at least one component in the form of a rare earth metal; from 0.1 to 5 wt.% of at least one component containing an alkali metal; and from 17 to 40 wt.% of chromium component; eta-alumina is the rest, and at least one component of the alkali metal comprises a compound of sodium, potassium, rubidium, or combinations thereof.

EFFECT: making a paraffin dehydrogenation catalyst characterized by increased crushing strength and increased thermal stability.

12 cl, 6 dwg, 2 tbl, 4 ex

Description

Cross-reference to related applications

This application claims the benefit of priority to U.S. Provisional Patent Application No. 62/742229, filed Oct. 5, 2018, and U.S. Provisional Patent Application No. 62/742231, filed Oct. 5, 2018, the entire contents of each being incorporated in their entirety. herein by reference.

Field of technology to which the invention relates

The present invention generally relates to catalysts for the dehydrogenation of paraffins. More specifically, the present invention relates to a carrier-modified wax dehydrogenation catalyst to improve crush strength.

Prior Art

Dehydrogenation of alkanes is a process used to produce a variety of alkene products. Examples of these alkene products include isobutylene, used to make methyl tert-butyl ether (MTBE), and propylene, used to make polypropylene. Currently, most commercially available alkane dehydrogenation technologies, including the Süd-Chemie CATOFIN® process, UOP's Oleflex® process, Phillips' Star™ process and the Snamprogetti-Yarsintez process, use fixed or fluidized bed reactors of various types.

One of the most common catalysts used for the dehydrogenation of alkanes is chromium oxide supported on alumina. Although this type of catalyst has been used for decades, there are a number of disadvantages associated with it when used in fixed bed reactors. First of all, the thermal stability of chromium-based catalysts is relatively low. Due to the high operating temperatures in both operation and regeneration modes of the alkane dehydrogenation process, poor thermal stability of the catalyst has a significant negative impact on the life expectancy of the catalyst bed, resulting in frequent catalyst replacement. Secondly, currently available chromium oxide catalysts generally do not have sufficient mechanical strength to support their own mass and withstand the turbulence of the alkane dehydrogenation process streams. During the dehydrogenation process, the mechanical strength of the catalyst gradually decreases to such a level that the catalyst must be removed from the production cycle, even though the metal elements in the catalysts are still active to catalyze the dehydrogenation reaction, resulting in the formation of waste active metals within the catalyst. Taking into account the above, the efficiency of traditional catalysts in the process of dehydrogenation of alkanes is relatively low.

In general, although catalysts for the dehydrogenation of alkanes exist, the need for improvements in this area continues to be relevant, at least in light of the above-mentioned disadvantages.

The essence of the invention

A solution has been found to at least some of the above problems associated with chromium-based catalysts. This solution consists of a catalyst comprising a rare earth modified support material and a method for producing the catalyst which includes multiple calcination steps. Namely, the chromium-aluminum catalyst prepared by this method exhibits increased crush strength compared to conventional chromium-based dehydrogenation catalysts. In addition, the catalyst prepared by this method exhibits improved thermal stability compared to a conventional chromium-based dehydrogenation catalyst. In general, the catalyst according to embodiments of the method of the invention has an increased life expectancy compared to a conventional dehydrogenation catalyst, resulting in lower production costs. With that said, the catalyst and methods of the present invention provide a technical solution to at least some of the problems associated with currently available alkane dehydrogenation catalysts.

Embodiments of the present invention include a wax dehydrogenation catalyst having increased crush strength. The paraffin dehydrogenation catalyst is prepared by a process comprising preparing a rare earth modified alumina support in the form of eta alumina, the form of theta alumina, or combinations thereof. The method further includes impregnating a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof, with a chromium-containing solution to produce a second support. The method further includes drying the second support and calcining the dried second support to obtain a wax dehydrogenation catalyst. This wax dehydrogenation catalyst has a crush strength higher than about 0.4 daN/mm. The paraffin dehydrogenation catalyst contains rare earth oxide in the range of 0.5-5 wt%. In embodiments of the invention, the rare earth oxide may comprise lanthanum oxide.

Embodiments of the invention include a wax dehydrogenation catalyst having increased crush strength. The wax dehydrogenation catalyst is prepared by a process comprising preparing a rare earth modified alumina support in the form of eta alumina, theta alumina or combinations thereof (step (a)). The method further includes impregnating the rare earth modified alumina support with a chromium-containing solution to obtain a second support. The method further includes drying the second support and calcining the dried second support to obtain a wax dehydrogenation catalyst. The wax dehydrogenation catalyst has a crush strength of more than about 0.4 daN/mm. The paraffin dehydrogenation catalyst contains rare earth oxide in the range of 0.5-5%, or 0.8-4%, or 0.5-1% by weight. In embodiments of the invention, the rare earth oxide may comprise lanthanum oxide. Preparation in step (a) involves preparing the eta-alumina support. The preparation in step (a) further includes impregnating the eta-aluminum oxide support with a solution containing a rare earth element to obtain a first support. Preparation in step (a), as previously described, further includes drying the first support and calcining the dried first support to obtain a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof.

Embodiments of the invention include a wax dehydrogenation catalyst having increased crush strength. The wax dehydrogenation catalyst is prepared by a process comprising preparing a rare earth modified alumina support in the form of eta alumina, theta alumina or combinations thereof (step (a)). The method further includes impregnating the rare earth modified alumina support with a chromium-containing solution to obtain a second support. The method further includes drying the second support and calcining the dried second support to obtain a wax dehydrogenation catalyst. The wax dehydrogenation catalyst has a crush strength of more than about 0.4 daN/mm. The paraffin dehydrogenation catalyst contains rare earth oxide in the range of 0.5-5%, or 0.8-4%, or 0.5-1% by weight. In embodiments of the invention, the rare earth oxide may comprise lanthanum oxide. Preparation in step (a) includes preparing an eta-alumina support precursor; contacting the precursor with a solution containing the rare earth element to obtain a bound precursor; forming a bound eta alumina support precursor; drying the bound precursor; and calcining the dried bound precursor to obtain a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof.

The following includes definitions of various terms and expressions used throughout this description.

The expressions “rare earth metal”, “rare earth additive” and “rare earth element” are used interchangeably herein.

The terms “about” or “approximately” are defined as being within the understanding of one skilled in the art. In one non-limiting embodiment, the terms are described to cover a range within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

The terms "wt%", "vol%" or "mol%" refer to the mass, volume or mole percentage of a component, respectively, based on the total mass, total volume or total number of moles of the material that includes the component. In a non-limiting example, 10 moles of a component in 100 moles of material constitutes 10 mole percent of the component.

The term “substantially” and variations thereof are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

The terms “inhibiting” or “reducing” or “preventing” or “eliminating” or any variant of these terms when used in the claims and/or description include any measurable reduction or complete inhibition to achieve the desired result.

The term "effective" as such used in the description and/or claims implies adequate to achieve the desired, expected or intended result.

The use of the words “a” or “an” when used in conjunction with the term “comprising”, “including”, “comprising” or “having” in a claim or description may mean “one” and is also consistent with the meaning "one or more", "at least one" and "one or more than one".

The words "encompassing" (and any form of "encompassing" such as "encompassing" and "encompassing"), "having" (and any form of "having" such as "have" and "has "), "including" (and any form of "including" such as "includes" and "include") or "containing" (and any form of "containing" such as "contains" and "comprise") are inclusive or open-ended expressions and do not exclude additional, unmentioned elements or method steps.

The method of the present invention may “comprise,” “consist essentially of,” or “consist of” specific ingredients, components, compositions, etc., disclosed throughout the specification.

The term “substantially” as used in the specification and/or claims implies a value greater than any of 50% by weight, 50% by weight, and 50% by volume. For example, "substantially" may include from 50.1 wt.% to 100 wt.% and all values and ranges therein between, from 50.1 mole.% to 100 mole.% and all values in between. values and ranges, as well as from 50.1 vol.% to 100 vol.% and all values and ranges between these values.

Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description and examples. It should be understood, however, that the figures, detailed description and examples, while showing specific embodiments of the invention, are provided by way of illustration only and are not intended to be limiting. In addition, it is intended that changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. In the following embodiments, features taken from specific embodiments may be combined with features taken from other embodiments. For example, features taken from one embodiment may be combined with features taken from any other embodiments. In the following embodiments, additional features may be added to the specific embodiments described herein.

Brief description of drawings

For a more complete understanding, reference is now made to the following descriptions, taken in conjunction with the accompanying drawings, in which:

in fig. 1 is a flow chart of a method for producing a wax dehydrogenation catalyst according to embodiments of the present invention;

in fig. 2 is a flow chart of a process for dehydrogenating lower wax using a catalyst according to embodiments of the present invention;

in fig. 3 shows a comparison of isobutylene yields when carrying out the dehydrogenation of isobutane using a traditional catalyst and the catalyst (example 2) corresponding to embodiments of this invention; And

in fig. 4 shows a comparison of the selectivities for converting isobutane to isobutylene using a conventional catalyst and a catalyst (Example 2) corresponding to embodiments of this invention;

in fig. 5 shows the yields of isobutylene when carrying out the dehydrogenation of isobutane using the catalyst (example 4) according to embodiments of this invention, before (A) and after (B) the first aging of the catalyst described in example 4;

in fig. 6 shows the selectivities for converting isobutane to isobutylene using the catalyst (Example 4) according to embodiments of the present invention, before (A) and after (B) the first aging of the catalyst described in Example 4.

Detailed Description of the Invention

Currently, wax dehydrogenation catalysts used in fixed bed reactors typically have low stability and limited mechanical strength, resulting in short catalyst life expectancy and high operating costs resulting from frequent catalyst replacement. The present invention provides a solution to these problems. This solution is based on a catalyst that includes a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof. The catalyst is prepared by performing multiple calcination steps and includes chromium and a rare earth element on an alumina support in the form of eta alumina, theta alumina, or combinations thereof. The stability and mechanical strength of this catalyst is increased compared to traditional chromium-based dehydrogenation catalysts, resulting in lower production costs for paraffin dehydrogenation. These and other non-limiting aspects of the present invention are discussed in more detail in the following sections.

A. Methods for preparing a catalyst for the dehydrogenation of paraffins

In embodiments of the present invention, the wax dehydrogenation catalyst may include a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof. With reference to FIG. 1 is a flow diagram of a process 100 for producing a wax dehydrogenation catalyst having increased crush strength compared to conventional wax dehydrogenation catalysts.

In embodiments of the invention, method 100 may include preparing a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof (step (a)), as shown in block 101. In embodiments of the invention, the rare earth element may include lanthanum, cerium, neodymium, or combinations thereof.

In embodiments of the invention, the production step at block 101 may include preparing an eta-aluminum oxide support, as shown in block 102. The production step at block 101 may further include impregnating the eta-aluminum oxide support with a solution containing a rare earth element to produce a first support, as shown in block 103. In embodiments of the invention, the preparation step in block 101, as before, may further include a heating step comprising drying the first support and calcining the dried first support to obtain a rare earth modified alumina support in the form of eta oxide aluminum, theta alumina, or combinations thereof, as shown in block 104.

In embodiments of the invention, the eta alumina carrier located in block 102 may include extruded cylindrical eta alumina pellets. In embodiments of the invention, non-limiting examples of a solution containing a rare earth element include a solution selected from the group consisting of solutions of lanthanum, cerium, neodymium, or combinations thereof. According to embodiments of the invention, the drying temperature in block 104 may be in the range from 70 to 150°C, including all ranges and values from 70 to 74°C, from 74 to 78°C, from 78 to 82°C, from 82 to 86 °C, 86 to 90°C, 90 to 94°C, 94 to 98°C, 98 to 102°C, 102 to 106°C, 106 to 110°C, 110 to 114° C, 114 to 118°C, 118 to 122°C, 122 to 126°C, 126 to 130°C, 130 to 134°C, 134 to 138°C, 138 to 142°C , from 142 to 146°C and from 146 to 150°C. Calcination in block 104 can be performed at temperatures ranging from 700 to 1000°C, including all ranges and values from 700 to 715°C, 715 to 730°C, 730 to 745°C, 745 to 760°C, from 760 to 775°C, from 775 to 790°C, from 790 to 805°C, from 805 to 820°C, from 820 to 835°C, from 835 to 850°C, from 850 to 865°C, from 865 to 880°C, from 880 to 895°C, from 895 to 910°C, from 910 to 925°C, from 925 to 940°C, from 940 to 955°C, from 955 to 970°C, from 970 up to 985°C and from 985 to 1000°C. The rate of increase in the calcination temperature in block 104 can be in the range from 0.5 to 10°C/min, including all ranges and values from 0.5 to 1°C/min, from 1 to 1.5°C/min, from 1.5 to 2.0°C/min, 2.0 to 2.5°C/min, 2.5 to 3.0°C/min, 3.0 to 3.5°C/min , from 3.5 to 4.0°C/min, from 4.0 to 4.5°C/min, from 4.5 to 5.0°C/min, from 5.0 to 5.5°C /min, from 5.5 to 6.0°C/min, from 6.0 to 6.5°C/min, from 6.5 to 7.0°C/min, from 7.0 to 7.5 °C/min, 7.5 to 8.0°C/min, 8.0 to 8.5°C/min, 8.5 to 9.0°C/min and 9.0 to 10 ,0°C/min. The duration of calcination in block 104 can be in the range from 0.5 to 4 hours and in all intermediate ranges and values. In embodiments of the invention, calcination in block 104 can be performed in an atmospheric environment containing oxygen, nitrogen, steam, or combinations thereof.

Additionally or alternatively, in embodiments of the invention, the production step at block 101 may include producing an eta-alumina support precursor as shown at block 105. The production step at block 101 may further include contacting the precursor with a solution containing a rare earth element, to produce a bound (contacted) precursor, as shown at block 106. The preparation step at block 101 may further include molding the bound precursor of the eta alumina support to produce a molded bound precursor, as shown at block 107. In embodiments of the invention, the precursor is brought into contacting the addition of at least one rare earth element in block 106 prior to the forming step in block 107. The production step in block 101, as before, may further include a heating step comprising drying the shaped bonded precursor and calcining the dried shaped a linked precursor to produce a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof, as shown in block 108.

In embodiments of the invention, the eta alumina support precursor may include bayerite, rho alumina, alumina gel (see Oxides and Hydroxides of Aluminum, Alcoa Technical Paper No. 19, revised by Karl Wefers and Chanakya Misra, Alcoa Laboratories 1987) or combinations thereof. In embodiments of the invention, non-limiting examples of a solution containing a rare earth element include a solution of lanthanum, cerium, neodymium compounds, or combinations thereof. According to embodiments of the invention, molding in block 107 may include extrusion, granulation, or combinations thereof. In embodiments of the invention, drying in block 108 may include drying temperatures in the range of 70 to 150°C, as well as all intermediate ranges and values. In embodiments of the invention, calcination in block 108 can be performed at a temperature in the range from 700 to 1000°C, as well as in the case of all intermediate ranges and values. The rate of increase in the calcination temperature in block 108 may be in the range of 0.5 to 10°C/min and all intermediate ranges and all intermediate values, including the range from 0.5 to 10°C/min and all intermediate ranges and all intermediate values, including ranges from 0.5 to 1°C/min, from 1 to 1.5°C/min, from 1.5 to 2.0°C/min, from 2.0 to 2.5°C /min, from 2.5 to 3.0°C/min, from 3.0 to 3.5°C/min, from 3.5 to 4.0°C/min, from 4.0 to 4.5 °C/min, 4.5 to 5.0°C/min, 5.0 to 5.5°C/min, 5.5 to 6.0°C/min, 6.0 to 6 .5°C/min, from 6.5 to 7.0°C/min, from 7.0 to 7.5°C/min, from 7.5 to 8.0°C/min, from 8.0 up to 8.5°C/min, from 8.5 to 9.0°C/min and from 9.0 to 10.0°C/min. The duration of calcination in block 108 can range from 0.5 to 4 hours and in all intermediate ranges and at all intermediate values. In embodiments of the invention, calcination in block 108 can be performed in an atmospheric environment containing oxygen, nitrogen, steam, or combinations thereof.

In embodiments of the invention, method 100 may further include impregnating a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof, with a chromium-containing solution to form a second support, as shown in block 109. In embodiments of the invention, the chromium-containing solution may include a chromium compound. Non-limiting examples of chromium compounds may include chromium hydroxide, sodium chromate, sodium dichromate, chromium nitrate, chromium acetate, chromium trioxide, and combinations thereof. Preferred chromium compounds are water-soluble chromium compounds. In embodiments of the invention, the impregnation step at block 109 further includes impregnating the rare earth modified alumina support with at least one alkali metal compound before or after impregnating the rare earth modified alumina support with the chromium-containing solution. In embodiments of the invention, a solution containing at least one alkali metal and chromium compound may be used to impregnate the rare earth modified alumina support. Typical alkali metal compounds include a sodium compound, a potassium compound, a rubidium compound, a cesium compound, and combinations thereof. In embodiments of the invention, the impregnation in block 109 comprises impregnation until the chromium compound content reaches up to and including 50%.

In embodiments of the invention, the method 100 may further include drying the second carrier to obtain a third carrier, as shown in block 110. In embodiments of the invention, the drying temperature in block 110 may be in the range of 70 to 150°C and in all intermediate ranges and ranges including 70 to 74°C, 74 to 78°C, 78 to 82°C, 82 to 86°C, 86 to 90°C, 90 to 94°C, 94 to 98 °C, 98 to 102°C, 102 to 106°C, 106 to 110°C, 110 to 114°C, 114 to 118°C, 118 to 122°C, 122 to 126° C, 126 to 130°C, 130 to 134°C, 134 to 138°C, 138 to 142°C, 142 to 146°C and 146 to 150°C.

In embodiments of the invention, method 100 may further include calcining a third support to produce a catalyst, as shown at block 111. When calcined at block 111, the chromium compound is substantially converted to chromium(III) oxide (Cr ₂ O ₃ ). In embodiments of the invention, the calcination temperature in block 111 may be in the range from 650 to 850°C, as well as in all intermediate ranges and values, including the ranges from 650 to 660°C, from 660 to 670°C, from 670 to 680° C, 680 to 690°C, 690 to 700°C, 700 to 710°C, 710 to 720°C, 720 to 730°C, 730 to 740°C, 740 to 750°C , from 750 to 760°C, from 760 to 770°C, from 770 to 780°C, from 780 to 790°C, from 790 to 800°C, from 800 to 810°C, from 810 to 820°C, 820 to 830°C, 830 to 840°C and 840 to 850°C. The rate of increase in the calcination temperature in block 111 can be in the range from 0.5 to 10°C/min, as well as in all intermediate ranges and values, including ranges from 0.5 to 1°C/min, from 1 to 1.5 °C/min, from 1.5 to 2.0°C/min, from 2.0 to 2.5°C/min, from 2.5 to 3.0°C/min, from 3.0 to 3 .5°C/min, from 3.5 to 4.0°C/min, from 4.0 to 4.5°C/min, from 4.5 to 5.0°C/min, from 5.0 up to 5.5°C/min, from 5.5 to 6.0°C/min, from 6.0 to 6.5°C/min, from 6.5 to 7.0°C/min, from 7 ,0 to 7.5°C/min, from 7.5 to 8.0°C/min, from 8.0 to 8.5°C/min, from 8.5 to 9.0°C/min and from 9.0 to 10.0°C/min. In embodiments of the invention, the duration of calcination in block 111 may be in the range from 0.5 to 4 hours, as well as in all intermediate ranges and values, including the ranges from 0.5 to 1 hour, from 1 to 1.5 hours, from 1 .5 to 2.0 hours, 2.0 to 2.5 hours, 2.5 to 3.0 hours, 3.0 to 3.5 hours and 3.5 to 4.0 hours. In embodiments of the invention, the calcination in block 111 can be performed in an atmospheric environment, for example, a second atmospheric environment containing air, carbon dioxide, steam, or combinations thereof.

In embodiments of the invention, the wax dehydrogenation catalyst produced by Method 100 may include from 5 to 40 wt% chromium oxide, preferably from 13 to 28 wt%, and all ranges and values therein, including the ranges from 13 to 14 wt.%, from 14 to 15 wt.%, from 15 to 16 wt.%, from 16 to 17 wt.%, from 17 to 18 wt.%, from 18 to 19 wt.%, from 19 to 20 wt. .%, from 20 to 21 wt.%, from 21 to 22 wt.%, from 22 to 23 wt.%, from 23 to 24 wt.%, from 24 to 25 wt.%, from 25 to 26 wt.% , from 26 to 27 wt.% and from 27 to 28 wt.%. The wax dehydrogenation catalyst produced by Method 100 may further include from 0.1 to 10 wt%, preferably from 1 to 5 wt%, oxides of at least one rare earth metal, and all ranges and values therein, including ranges from 1 to 1.2 wt.%, from 1.2 to 1.4 wt.%, from 1.4 to 1.6 wt.%, from 1.6 to 1.8 wt.%, from 1, 8 to 2.0 wt.%, from 2.0 to 2.2 wt.%, from 2.2 to 2.4 wt.%, from 2.4 to 2.6 wt.%, from 2.6 to 2.8 wt.%, from 2.8 to 3.0 wt.%, from 3.0 to 3.2 wt.%, from 3.2 to 3.4 wt.%, from 3.4 to 3, 6 wt.%, from 3.6 to 3.8 wt.%, from 3.8 to 4.0 wt.%, from 4.0 to 4.2 wt.%, from 4.2 to 4.4 wt. .%, from 4.4 to 4.6 wt.%, from 4.6 to 4.8 wt.% and from 4.8 to 5.0 wt.%. In embodiments of the invention, the wax dehydrogenation catalyst produced by method 100 may further include from 0.1 to 5 wt.% of at least one alkali metal, as well as all intermediate ranges and values, including ranges from 0. 1 to 0.2 wt.%, from 0.2 to 0.3 wt.%, from 0.3 to 0.4 wt.%, from 0.4 to 0.5 wt.%, from 0.5 to 0.6 wt.%, from 0.6 to 0.7 wt.%, from 0.7 to 0.8 wt.%, from 0.8 to 0.9 wt.%, from 0.9 to 1, 0 wt.%, from 1 to 1.2 wt.%, from 1.2 to 1.4 wt.%, from 1.4 to 1.6 wt.%, from 1.6 to 1.8 wt.% , from 1.8 to 2.0 wt.%, from 2.0 to 2.2 wt.%, from 2.2 to 2.4 wt.%, from 2.4 to 2.6 wt.%, from 2.6 to 2.8 wt.%, from 2.8 to 3.0 wt.%, from 3.0 to 3.2 wt.%, from 3.2 to 3.4 wt.%, from 3, 4 to 3.6 wt.%, from 3.6 to 3.8 wt.%, from 3.8 to 4.0 wt.%, from 4.0 to 4.2 wt.%, from 4.2 to 4.4 wt%, 4.4 to 4.6 wt%, 4.6 to 4.8 wt% and 4.8 to 5.0 wt%. In embodiments of the invention, the remainder of the catalyst is eta alumina, theta alumina, or combinations thereof.

In embodiments of the invention, the wax dehydrogenation catalyst has a surface area in the range of 60 to 120 m ² /g, and all intermediate ranges and values, including the ranges of 60 to 63 m ² /g, 63 to 66 m ² /g, from 66 to 69 m ² /g, from 69 to 72 m ² /g, from 72 to 75 m ² /g, from 75 to 78 m ² /g, from 78 to 81 m ² /g, from 81 to 84 m ² /g, from 84 to 87 m ² /g, from 87 to 90 m ² /g, from 90 to 93 m ² /g, from 93 to 96 m ² /g, from 96 to 99 m ² /g, from 99 to 102 m ² /g, from 102 to 105 m ² /g, from 105 to 108 m ² /g, from 108 to 111 m ² /g, from 111 to 114 m ² /g, from 114 to 117 m ² /g and from 117 to 120 m ² /g. The pore volume (nitrogen adsorption-desorption) of the wax dehydrogenation catalyst can be in the range from 0.1 to 0.4 cm ³ /g, as well as in all intermediate ranges and values, including ranges from 0.1 to 0.15 cm ³ / g, from 0.15 to 0.20 cm ³ /g, from 0.20 to 0.25 cm ³ /g, from 0.25 to 0.30 cm ³ /g, from 0.30 to 0.35 cm ³ /g and from 0.35 to 0.40 cm ³ /g. In embodiments of the invention, the wax dehydrogenation catalyst has a bulk density in the range of 0.8 to 1.2 g/ml, and in all intermediate ranges and values, including the ranges from 0.8 to 0.85 g/ml, from 0. 85 to 0.90 g/ml, from 0.90 to 0.95 g/ml, from 0.95 to 1.0 g/ml, from 1.05 to 1.10 g/ml, from 1.10 to 1.15 g/ml and 1.15 to 1.20 g/ml. In embodiments of the invention, the wax dehydrogenation catalyst may have a crush strength of about 0.4 daN/mm or greater.

B. Methods for paraffin dehydrogenation

As shown in FIG. 2, embodiments of the invention include a method 200 for dehydrogenating lower wax. In embodiments of the invention, the lower paraffin may include ethane, propane, butane, isobutane, pentane, or combinations thereof. Method 200 can be implemented using a wax dehydrogenation catalyst produced by method 100, as shown in FIG. 1. According to embodiments of the invention, as shown in block 201, method 200 may include preparing a wax dehydrogenation catalyst prepared by method 100.

In embodiments of the invention, the method 200 may further include placing a wax dehydrogenation catalyst in a reactor, as shown at block 202. In embodiments of the invention, the reactor may be a fixed bed reactor. In embodiments of the invention, the fixed bed of catalyst in the reactor may comprise paraffin dehydrogenation catalyst particles having a diameter in the range of 2 to 4 mm, as well as in all intermediate ranges and values, including the ranges of 2 to 2.1 mm, from 2, 1 to 2.2 mm, from 2.2 to 2.3 mm, from 2.3 to 2.4 mm, from 2.4 to 2.5 mm, from 2.5 to 2.6 mm, from 2, 6 to 2.7 mm, from 2.7 to 2.8 mm, from 2.8 to 2.9 mm, from 2.9 to 3.0 mm, from 3.0 to 3.1 mm, from 3, 1 to 3.2 mm, from 3.2 to 3.3 mm, from 3.3 to 3.4 mm, from 3.4 to 3.5 mm, from 3.5 to 3.6 mm, from 3, 6 to 3.7 mm, 3.7 to 3.8 mm, 3.8 to 3.9 mm and 3.9 to 4.0 mm. In embodiments of the invention, the fixed catalyst bed in the reactor may further comprise alpha-alumina, a fuel-generating material, or combinations thereof.

In embodiments of the invention, method 200 may further include reacting the lower wax in the presence of a wax dehydrogenation catalyst under reaction conditions adequate to dehydrogenate the lower wax, as shown at block 203. In embodiments, the reaction conditions at block 203 may include temperature reactions from 400 to 800°C, and all intermediate ranges and values, including the ranges from 400 to 420°C, from 420 to 440°C, from 440 to 460°C, from 460 to 480°C, from 480 up to 500°C, from 500 to 520°C, from 520 to 540°C, from 540 to 560°C, from 560 to 580°C, from 580 to 600°C, from 600 to 620°C, from 620 to 640°C, from 640 to 660°C, from 660 to 680°C, from 680 to 700°C, from 700 to 720°C, from 720 to 740°C, from 740 to 760°C, from 760 to 780 °C and 780 to 800°C. The reaction conditions at block 203 may further include a reaction pressure of 0.2 to 1 bar, as well as all intermediate ranges and values, including 0.3 bar, 0.4 bar, 0.5 bar, 0.6 bar, 0 .7 bar, 0.8 bar and 0.9 bar. Reaction conditions may further include gas and/or mass hourly space velocity ranging from 300 to 800 h ^-1 , as well as being in all intermediate ranges and values, including the ranges from 300 to 320 h ^-1 , from 320 to 340 h ^-1 , from 340 to 360 h ^-1 , from 360 to 380 h ^-1 , from 380 to 400 h ^-1 , from 400 to 420 h ^-1 , from 420 to 440 h ^-1 , from 440 to 460 h ^-1 , from 460 to 480 h ^-1 , from 480 to 500 h ^-1 , from 500 to 520 h ^-1 , from 520 to 540 h ^-1 , from 540 to 560 h ^-1 , from 560 to 580 h ^-1 , from 580 to 600 h ^-1 , from 600 to 620 h ^-1 , from 620 to 640 h ^-1 , from 640 to 660 h ^-1 , from 660 to 680 h ^-1 , from 680 to 700 h ^-1 , from 700 to 720 h ^-1 , from 720 to 740 h ^-1 , from 740 to 760 h ^-1 , from 760 to 780 h ^-1 and from 780 to 800 h ^-1 . In embodiments of the invention, the reaction in block 203 is carried out at an hourly gas space velocity in the range from 250 to 750 ml h ^-1 g ^-1 , preferably from 350 to 650 ml h ^-1 g ^-1 , more preferably from 400 to 600 ml h ^-1 g ^-1 .

As shown at block 204, method 200 may further include the steps of oxidizing and reducing a wax dehydrogenation catalyst. In embodiments of the invention, the oxidation and reduction in block 204, as well as the reaction in block 203, are repeated in a cyclic manner. An inert gas such as steam or nitrogen may be passed through the reactor between any or all of the oxidation, reduction and reaction steps.

Although embodiments of the present invention have been described with reference to the blocks of FIGS. 1 and 2, it should be appreciated that the operation of the present invention is not limited to the specific blocks and/or the specific order of blocks illustrated in FIG. 1 and 2. Accordingly, embodiments of the present invention may provide the functionality described herein using various blocks in a sequence different from that shown in FIG. 1 and 2.

As part of the disclosure of the present invention, specific examples are included below. These examples are provided for illustrative purposes only and are not intended to limit the invention. Those of ordinary skill in the art will readily recognize parameters that can be changed or modified to achieve substantially the same results.

Examples

Comparative example 1

(Preparation of catalyst without rare earth element, comparative example)

Eta-alumina extrudates (approximately 3.1 mm x 8.9 mm in size) with a surface area of 335 m ² /g were used to prepare the catalyst. One hundred grams of alumina support was heat treated (calcined) in the presence of air in a tube furnace at 800° C. for 2 hours at an air flow rate of 21 ml/min. Calcined extrudates were used to prepare the catalyst using the moisture-capacity impregnation method. The water pore volume of the extrudates (the surface area that changes during calcination) was measured by taking 5 grams of the carrier and titrating it with demineralized water. The end point was the point at which the extrudates adhered to the surface of the glassware. It was determined that the measured water pore volume was 0.39 ± 0.1 cm ³ /g.

About 100 ml of a stock solution of chromium (VI) oxide (CrO ₃ ) was prepared by dissolving 114 g of CrO ₃ in water. The impregnating solution was prepared by dissolving 0.77 g of NaOH in 17.4 ml of the original chromium solution. Before impregnation with chromium, the extrudates were dried at 120°C for 2 hours.

Impregnation was carried out by bringing the impregnation solution into contact with 44.4 g of heat-treated and dried alumina carrier at room temperature. Thereafter, the impregnated alumina support was kept at room temperature for 2 hours and then dried at 120°C for 12 hours.

The dried sample was then calcined at 650°C for 2 hours in air (flow rate 240 ± 5 ml/min), followed by calcination at 750°C for 4 hours in an environment consisting of 80% air and 20% water vapor (total flow rate 240 ± 5 ml/g/h). After calcination, the catalyst was cooled in air and then stored in an airtight container. The final calculated catalyst composition was 25 wt.% Cr ₂ O ₃ and 1 wt.% Na ₂ O, with the remainder corresponding to Al ₂ O ₃ .

Example 2

(Preparation of a catalyst containing a rare earth metal)

Etha-alumina extrudates (~3.1 mm x ~8.9 mm in size) having a surface area of 335 m ² /g were used to prepare the catalyst. This support was heat treated in air at 120°C for 2 hours. 4.78 g of La(NO ₃ ) ₃ ·6H ₂ O was dissolved in 22.6 ml of water and soaked in 58 g of etha-alumina. This La ₂ O ₃ impregnation material was kept at room temperature for 2 hours, dried at 120°C for 12 hours and calcined in the presence of air in a tube furnace at 800°C for 2 hours (air flow 21 ml/min). Calcined extrudates were used to prepare the catalyst using the moisture-capacity impregnation method.

The volume of pores occupied by water in calcined extrudates was measured by taking 5 grams of the carrier and titrating it with demineralized water. The end point was the point at which the extrudates adhered to the surface of the glassware. It was determined that the measured volume of pores occupied by water was 0.39 ± 0.1 cm ³ /g.

A 100 ml stock solution of chromium (VI) oxide (CrO ₃ ) was prepared by dissolving 114 g of CrO ₃ in water. The impregnating solution was prepared by dissolving 0.77 g of NaOH in 17.4 ml of the original chromium solution.

Before impregnation with chromium, the aluminum oxide was dried at 120°C for 2 hours. Impregnation was carried out by contacting the impregnation solution with 44.4 g of heat-treated and dried alumina carrier at room temperature. The impregnated alumina support was kept at room temperature for 2 hours and then dried at 120°C for 12 hours. After this, the dried sample was calcined at 650°C for 2 hours in air (flow rate 240 ± 5 ml/min), and then at 750°C for 4 hours in an environment consisting of 80% air and 20% steam (total flow rate 240 ± 5ml/g/h). After calcination, the catalyst was cooled in air and then stored in an airtight container. The final catalyst composition calculated was 25 wt% Cr ₂ O ₃ , 3 wt% La ₂ O ₃ and 1 wt% Na ₂ O, with the remainder being Al ₂ O ₃ .

Example 3

(Testing catalysts)

Catalyst crush strength testing

The radial crush strength of the catalysts prepared in Examples 1 and 2 was measured. About 50 g of the catalyst was dried in an oven at 300°C for 2 hours. After cooling the catalysts, 30 extrudates were used in the desiccator. Each extrudate was subjected to increased stress until fracture was achieved. The force applied to the extrudate at the moment of fracture is determined in decaNewtons (daN), and the results for crushing strength are expressed in daN/mm and are shown in Tables 1 and 2.

Table 1: Crushing Strength of Catalyst Prepared Using the Method of Example 1

Comparative example 1 Minimum value Average value Maximum
meaning Standard deviation Nominal diameter (mm) 2.8 3.07 3.27 0.12 Crushing diameter (mm) 2.69 2.96 3.22 0.14 Crushing force (daN) 1.6 2.93 4.82 0.92 Tilt (daN/mm) 1.36 41.7 85.57 24.49 Crushing strength (daN/mm) 0.23 0.41 0.83 0.15 Load increase rate (daN/s) 0.1 0.42 0.86 0.24

Table 2: Crushing Strength of Catalyst Prepared Using the Method of Example 2

Example 2 Minimum value Average value Maximum
meaning Standard deviation Nominal diameter (mm) 2.87 3.23 3.45 0.15 Crushing diameter (mm) 2.68 3.04 3.32 0.18 Crushing force (daN) 3.19 5.58 10.90 1.80 Tilt (daN/mm) 6.90 48.16 109.04 32.44 Crushing strength (daN/mm) 0.30 0.69 1.18 0.21 Load increase rate (daN/s) 0.07 0.48 1.09 0.32

As shown in Tables 1 and 2, the crush strength of catalysts containing a rare earth element is higher than that of catalysts that do not contain a rare earth element. The average increase in crush strength is about 41%.

Catalyst activity testing

The activity of the catalysts in dehydrogenation was determined in a tubular quartz reactor with a fixed catalyst bed. Details regarding catalyst and reactor loading were as follows: catalyst weight was 5 g, catalyst particle size was 0.4-0.5 mm, reactor internal diameter was 16 mm, reactor external diameter was 19 mm.

Isobutane (99.9 vol.%) was used as the starting material. Quartz chips with a particle size of 1-1.4 mm were loaded above the catalyst layer. Nitrogen purge was used between the stages of dehydrogenation, catalyst regeneration/oxidation and hydrogen reduction. The total feed flow rate at the dehydrogenation stage corresponds to an hourly gas volumetric velocity (GHSV) of 600 mlh ^-1 g ^-1 . Gases leaving the reactor were analyzed using an in-line gas chromatograph (Agilent 6890) equipped with a flame ionization detector for hydrocarbon analysis and a thermal conductivity detector for hydrogen analysis. Reactant and product flow rates were measured using a Ritter wet gas flow meter.

The reactor was operated at atmospheric pressure and in a cyclic mode using the following stages: 1) oxidation in air at 650°C for 30 min; 2) nitrogen purging at 650°C for 10 minutes; 3) reduction of _H2 with hydrogen at 650°C for 6 minutes; 4) cooling in nitrogen from 650°C to 585°C, then holding at 585°C for 40 minutes; 5) dehydrogenation of isobutane at 585°C for 21 minutes; and 6) analysis using a gas chromatograph (GC) at 20 minutes from the start of isobutane feedstock. Stages 1 - 6 were repeated several times.

Catalyst stability testing

The stability of the catalysts was assessed using an artificial accelerated aging procedure in a cyclic operating mode. The cycle consisted of stages of passing hydrogen-isobutane-air, separated by various time intervals. Aging was carried out at 820°C for 72 hours, and the second aging was performed at 820°C for 48 hours. Parameters for assessing catalyst stability included a catalyst mass of 5 g, an isobutane GHSV rate of 400 ml⋅g ^-1 ⋅h ^-1 , and an air to isobutane volume ratio of 4. The following steps were performed: 1) oxidation in air within 15 minutes; 2) purging with nitrogen for 3 minutes; 3) reduction of H ₂ for 6 minutes; 4) purging with nitrogen for 3 minutes; 5) passing a stream of isobutane for 3 minutes; 6) purging with nitrogen for 3 minutes.

Results of testing the activity and stability of catalysts

Comparison of outputs

As shown in FIG. 3, the two types of catalysts (Comparative Example 1 catalyst containing no rare earth metal and Example 2 catalyst containing the rare earth metal compound lanthanum oxide) exhibited comparable isobutylene yields over the first 22 cycles. Catalysts that were aged using an artificially accelerated aging procedure showed a noticeable difference in isobutylene yield. The catalysts of Example 2 (a catalyst containing a rare earth metal compound, lanthanum oxide) exhibited isobutylene yields above 40% over cycles 24-47. Over the same period of cycling, the catalysts of Example 1 (without the rare earth metal) exhibited a yield of about 36%. The difference in yields was even more significant during cycles 49-65. During this period, the catalyst containing lanthanum oxide (Example 2) showed an isobutylene yield above 33%. The results indicate that the catalyst prepared using etha alumina modified with lanthanum oxide was more stable compared to the unmodified catalyst.

Selectivity comparison

As shown in FIG. 4, the two types of catalysts (Comparative Example 1 catalyst containing no rare earth metal and Example 2 catalyst containing the rare earth metal compound lanthanum oxide) resulted in similar isobutylene selectivities over the first 22 cycles. After the implementation of the artificial accelerated aging process, the selectivities of the catalysts began to diverge to a moderate extent. The catalysts of example 2 (a catalyst containing a compound containing a rare earth metal, lanthanum oxide) demonstrated slightly increased selectivity for isobutylene over cycles 24-47. The difference in selectivity increased over cycles 49–65. The lanthanum oxide containing catalyst (Example 2) exhibited an isobutylene selectivity of about 93%, compared to the selectivity of the catalyst not containing lanthanum oxide (Comparative Example 1) of about 89%. The selectivity results show that the catalyst containing the rare earth metal lanthanum oxide exhibited superior performance over time compared to the catalyst without lanthanum oxide.

Example 4

(Catalyst containing rare earth metal)

Catalyst Preparation: The catalyst was prepared by impregnation using etha-alumina extrudates as an alumina support. Eta-alumina extrudates were prepared according to the following procedure. Bayerite material (Pural-BT, Sasol) was extruded using nitric acid as a peptising agent. The said bayerite powder (800 g) placed in a Sigma kneading machine was dry mixed at a speed of about 45 rpm for a period of 5 to 10 minutes, and then 44.8 ml of deionized water for a period of time from 10 to 15 minutes. Then 160 ml of nitric acid at a concentration of 37% by volume was added dropwise and the mixture was stirred for approximately 30 minutes. 2.64 g of hydroxylpropyl methylcellulose (HPMC) was then slowly added in portions and mixing continued for an additional 20 to 30 minutes. The resulting thick mass was then extruded using a laboratory extruder (Sunsai) with heads having round holes of 3.5 mm in diameter. The resulting extrudates were then kept at 25°C for two hours. The extrudates were then placed in an oven at 70°C for 30 minutes, and then cooled to 25°C, held for 12 hours, and placed back in the oven at 70°C for 12 hours. The extrudates were then cooled to 25°C, separated and broken into particles 6 - 8 mm long. Thereafter, said extrudates were dried at 90°C and 120°C for 12 hours in each case. Then, 450 g of dried extrudates were placed in a fixed bed tubular reactor and calcined at 550°C in air for 3 hours, with an air flow (ml/min) equal to the volume of alumina extrudates. After cooling to room temperature, the calcined alumina extrudates were used to prepare the catalyst. The impregnation solution was prepared according to the following procedure. An aqueous solution of chromic acid was prepared by dissolving 451 g of CrO ₃ in 400 ml of water. Then 14 g of lanthanum oxide was dissolved in the chromic acid solution by slowly adding with stirring. An aqueous sodium hydroxide solution was then prepared by dissolving 18 g of sodium hydroxide in 40 ml of water and then adding it to a chromic acid solution containing lanthanum oxide. An additional 55 ml of water was added to the above solution and mixed well. Impregnation was carried out using a double-cone mixer. Eta-alumina extrudates (1000 g; 3.2 mm x 6-8 mm) were placed in a double-cone mixer. While rotating the two-cone mixer (15 rpm), the impregnation solution was added to the mixer along with the air flow for 2 hours using a peristatic pump. After impregnation was completed, the mixer was allowed to rotate at 15 rpm for 1 hour. The mixer was then rotated at 15 rpm while blowing air for 15 hours. After 15 hours, the mixer rotation and air flow were stopped, the chromic acid-impregnated extrudates were discharged into glass trays and dried at 70°C for 12 hours. The impregnated alumina extrudates were then dried at 120°C for 15 hours. The dried material was calcined by loading 500 g of the dried impregnated material into a fixed bed tubular quartz reactor. The catalyst was calcined at 650°C for 2 hours in an air stream (1375 ml/min), and then at 750°C for 4 hours in the presence of a mixture consisting of 13 volume % steam and 87 volume % air (at a total flow rate 1575 ml/min).

Catalyst Crushing Strength Test: The radial crush strength of the catalysts prepared in Example 4 was measured. About 50 g of the catalyst was dried in an oven at 300° C. for 2 hours. After cooling the catalysts, 30 extrudates were used in the desiccator. Each extrudate was subjected to increasing load until failure was achieved. The force applied to the extrudate at the moment of fracture is defined in decaNewtons (daN), and the crushing strength results are expressed in units of daN/mm. The average crush strength of the catalyst was found to be 1.5 daN/mm.

Catalyst Activity Test: The dehydrogenation activity of the catalysts was determined in a tubular quartz fixed bed reactor. Details regarding catalyst and reactor loading were as follows: catalyst weight was 5 g, catalyst particle size was 0.4-0.5 mm, reactor internal diameter was 16 mm, reactor external diameter was 19 mm.

Isobutane (99.9 vol.%) was used as the starting material. Quartz chips with a particle size of 1-1.4 mm were loaded above the catalyst layer. Nitrogen purge was used between the stages of dehydrogenation, catalyst regeneration/oxidation and hydrogen reduction. The total feed flow rate at the dehydrogenation stage corresponds to an hourly gas volumetric velocity (GHSV) of 600 mlh ^-1 g ^-1 . Gases leaving the reactor were analyzed using an in-line gas chromatograph (Agilent 6890) equipped with a flame ionization detector for hydrocarbon analysis and a thermal conductivity detector for hydrogen analysis. Reactant and product flow rates were measured using a Ritter wet gas flow meter.

The reactor was operated at atmospheric pressure and in a cyclic mode using the following stages: 1) oxidation in air at 650°C for 30 min; 2) nitrogen purging at 650°C for 10 minutes; 3) reduction of _H2 with hydrogen at 650°C for 6 minutes; 4) cooling in nitrogen from 650°C to 585°C, then holding at 585°C for 40 minutes; 5) dehydrogenation of isobutane at 585°C for 21 minutes; and 6) analysis using a gas chromatograph (GC) at 20 minutes from the start of isobutane feedstock. Stages 1 - 6 were repeated several times.

Catalyst stability testing: The stability of the catalyst was assessed through an artificial accelerated aging procedure in a cyclic mode. The cycle consisted of stages of passing hydrogen-isobutane-air, separated by various time intervals. Aging was carried out at 820°C for 72 hours, and the second aging was performed at 820°C for 48 hours. Parameters for assessing catalyst stability included a catalyst mass of 5 g, an isobutane GHSV rate of 400 ml⋅g ^-1 ⋅h ^-1 , and an air to isobutane volume ratio of 4. The following steps were performed: 1) oxidation in air within 15 minutes; 2) purging with nitrogen for 3 minutes; 3) reduction of H ₂ for 6 minutes; 4) purging with nitrogen for 3 minutes; 5) passing a stream of isobutane for 3 minutes; 6) purging with nitrogen for 3 minutes. The yield of isobutylene and the selectivity of the catalyst for isobutylene before and after the first aging are shown in Fig. 5 and fig. 6, respectively.

At least the following 34 embodiments have been described in connection with the present invention. Embodiment 1 is a wax dehydrogenation catalyst characterized by increased crush strength. This wax dehydrogenation catalyst is prepared by a process comprising: (a) preparing a rare earth modified alumina support in the form of eta alumina, theta alumina, or combinations thereof; (b) impregnating the rare earth modified alumina support with a chromium-containing solution to obtain a second support; (c) drying the second carrier to obtain a third carrier; and (d) calcining the third support to obtain a wax dehydrogenation catalyst having a crush strength greater than about 0.4 daN/mm and further containing a rare earth metal oxide in the range of 0.5-5 wt%. Embodiment 2 is the catalyst of Embodiment 1, for which the production in step (a) includes: (e) producing an eta-alumina support; (f) impregnating the eta-aluminum oxide support with a solution containing a rare earth compound to obtain a first support; and (g) drying the first support and calcining the dried first support to obtain a rare earth modified alumina support in the form of eta alumina, theta alumina, or a combination thereof. Embodiment 3 is the catalyst of Embodiment 2, for which the calcination in step (g) is carried out at a calcination temperature of 700 to 1000°C. Embodiment 4 is the catalyst of Embodiment 1, for which the production in step (a) includes: (h) producing an eta alumina support precursor; (i) contacting the precursor with a rare earth compound to produce a bound precursor; (j) molding the bound eta alumina support precursor to form a molded bound precursor; and (k) drying the shaped bonded precursor and calcining the dried bonded precursor to obtain a rare earth modified support in the form of eta alumina, theta alumina, or a combination thereof. Embodiment 5 is the catalyst of Embodiment 4, wherein the eta alumina support precursor comprises bayerite, po-alumina, aluminogel, or combinations thereof. Embodiment 6 is the catalyst of embodiment 4 or 5, wherein the molding in step (j) includes extrusion. Embodiment 7 is a catalyst of any one of embodiments 4 to 6, in which the calcination in step (k) is performed at a calcination temperature of 700 to 1000°C. Embodiment 8 is a catalyst of any one of embodiments 4 to 7, wherein the rare earth element containing compound comprises a lanthanum compound, a cerium compound, a neodymium compound, or combinations thereof. Embodiment 9 is a catalyst of any of embodiments 1 to 8, in which the chromium-containing solution comprises an alkali metal hydroxide, an alkali metal chromate, an alkali metal dichromate, or combinations thereof. Embodiment 10 is a catalyst of any one of embodiments 1 to 9, in which the calcination in step (d) is performed at a calcination temperature of 650 to 850°C or 700 to 850°C. Embodiment 11 is a catalyst of any of embodiments 1 to 10, wherein the wax dehydrogenation catalyst contains 5 to 30 wt% or 13 to 28 wt% chromium and 0.1 to 5 wt% or 0. 4 to 4.3 wt.% rare earth element. Embodiment 12 is a catalyst of any of embodiments 1 to 11, wherein the wax dehydrogenation catalyst has a surface area in the range of 60 to 120 m ² /g.

Embodiment 13 is a method for dehydrogenating lower paraffin. This method involves preparing a wax dehydrogenation catalyst according to any one of embodiments 1 to 12. The method further includes placing a wax dehydrogenation catalyst in a reactor and reacting the lower wax in the presence of the wax dehydrogenation catalyst under reaction conditions adequate to dehydrogenate the lower wax. Embodiment 14 is the method of embodiment 13 in which the lower paraffin comprises propane, butane, pentane, or combinations thereof. Embodiment 15 is the method of embodiment 13 or 14 in which the reactor includes a fixed bed reactor. Embodiment 16 is a method of any of embodiments 13 to 15, wherein the reaction conditions include a reaction temperature of 400 to 800°C.

Embodiment 17 is a method for producing a catalyst. The method includes: (a) contacting an etha alumina precursor with the addition of at least one rare earth component to produce a bound eta alumina precursor; (b) heating the bound etha alumina precursor to produce rare earth modified eta alumina, theta alumina, or a combination thereof; (c) impregnating the rare earth modified alumina with a chromium compound; and (d) heating the chromium-impregnated alumina to obtain a catalyst. Embodiment 18 is the method of Embodiment 17, in which the chromium compound impregnation step includes impregnation to achieve a chromium compound content of up to 50%. Embodiment 19 is the method of Embodiment 17 or 18, in which the chromium compound impregnation step further includes impregnation with at least one alkali metal compound. Embodiment 20 is the method of Embodiment 19, in which the at least one alkali metal compound comprises a sodium compound, a potassium compound, a rubidium compound, a cesium compound, or a combination thereof. Embodiment 21 is a method of any one of embodiments 17 to 20, wherein the method for producing the catalyst further includes a molding step. Embodiment 22 is the method of Embodiment 21 in which the eta-alumina precursor is contacted with an addition of at least one rare earth component prior to the molding step. Embodiment 23 is a method of any of embodiments 17 to 22, in which the heating step includes a drying step and a calcination step.

Embodiment 24 is a method for producing a catalyst. The method includes: (a) impregnating eta alumina, theta alumina, or a combination thereof with an addition of at least one rare earth component and at least one chromium compound; and (b) heating the impregnated alumina to obtain a catalyst. Embodiment 25 is the method of embodiment 24, wherein the impregnation step includes impregnation to achieve a chromium compound content of up to 50%. Embodiment 26 is the method of embodiment 24, wherein the impregnation step further includes impregnation with at least one alkali metal compound. Embodiment 27 is the method of Embodiment 25, in which the at least one alkali metal compound comprises a sodium compound, a potassium compound, a rubidium compound, a cesium compound, or a combination thereof. Embodiment 28 is a method of any of embodiments 24-27, wherein the method further includes the step of molding.

Embodiment 29 is a method for producing a catalyst. The method includes: (a) treating a combination of a rare earth additive and eta alumina by heating to produce rare earth modified eta alumina, theta alumina, or a combination thereof; (b) impregnating the rare earth modified alumina with a chromium compound; and (c) heating the impregnated alumina to obtain a catalyst. Embodiment 30 is the method of Embodiment 29, in which the chromium compound impregnation step includes impregnation to achieve a chromium compound content of up to 50%. Embodiment 31 is the method of Embodiment 29 or 30, in which the chromium compound impregnation step further includes impregnation with at least one alkali metal compound. Embodiment 32 is the method of Embodiment 31, in which the at least one alkali metal compound includes a sodium compound, a potassium compound, a rubidium compound, a cesium compound, or a combination thereof. Embodiment 33 is a method of any of embodiments 29-32, wherein the method further includes the step of molding.

Embodiment 34 is a wax dehydrogenation catalyst. The catalyst includes a support containing eta-alumina, theta-alumina, or a combination thereof. The catalyst further includes from 0.1 to 10 wt.% component of at least one rare earth metal. The catalyst, as before, additionally contains from 0.1 to 5 wt.% of at least one component containing an alkali metal. The catalyst also includes from 5 to 40% by weight of a chromium component, with the remainder of the catalyst being eta alumina, theta alumina, or a combination thereof.

Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and conversions can be made within the scope of this document without departing from the spirit and scope of the embodiments set forth in the claims. Moreover, the scope of this application is not intended to limit the specific embodiments of the process, machine, manufacture, material composition, apparatus, methods and steps set forth herein. Thus, one of ordinary skill in the art will readily appreciate from the foregoing disclosure that processes, machines, fabrication, material compositions, devices, methods or steps may be used, presently existing or hereafter to be developed, that accomplish substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, devices, methods or steps.

Claims (26)

1. A method for producing a catalyst for the dehydrogenation of paraffins, characterized by increased crushing strength, including the following: (a) obtaining a rare earth element modified alumina support in the form of eta alumina containing a rare earth element containing compound; (b) impregnating the rare earth modified alumina support with a chromium-containing solution to obtain a second support; (c) drying the second carrier to obtain a third carrier; (d) calcining the third support to obtain a wax dehydrogenation catalyst; wherein the paraffin dehydrogenation catalyst has a crushing strength of more than about 0.4 daN/mm, and wherein the paraffin dehydrogenation catalyst contains a rare earth metal oxide in the range of 0.5-5 wt.%, chromium oxide in the range of 17-40 wt.%, at least one alkali metal component in the range of 0.1-5 wt.%, eta-alumina - the rest, wherein at least one alkali metal component contains a compound of sodium, potassium, rubidium or combinations thereof, and obtaining at stage (a ) includes the following: (e) obtaining an eta-alumina support; (f) impregnating the eta-alumina support with a solution containing a rare earth compound to obtain a first support; And (g) drying the first support and calcining the dried first support to obtain a rare earth modified alumina support in the form of etha alumina. 2. The method according to claim 1, where the chromium-containing solution contains an alkali metal hydroxide, an alkali metal chromate, an alkali metal dichromate, or combinations thereof. 3. The method of claim 1, wherein the rare earth element containing compound includes a lanthanum compound, a cerium compound, a neodymium compound, or combinations thereof. 4. The method of claim 1, wherein the rare earth element containing compound comprises a lanthanum compound. 5. The method according to claim 1, wherein the rare earth element containing compound includes a cerium compound. 6. The method of claim 1, wherein the rare earth element containing compound comprises a neodymium compound. 7. The method according to claim 1, where the chromium-containing solution contains an alkali metal hydroxide. 8. The method according to claim 1, where the chromium-containing solution contains an alkali metal chromate. 9. Method according to any one of paragraphs. 1-8, wherein the alkali metal compound includes a sodium compound. 10. Method according to any one of paragraphs. 1-9, where the calcination in step (d) is carried out at a calcination temperature of from 650 to 850°C. 11. Method according to any one of paragraphs. 1-10, where the wax dehydrogenation catalyst contains 25 wt.% Cr ₂ O ₃ , 3 wt.% La ₂ O ₃ , and 1 wt.% Na ₂ O. 12. A catalyst for the dehydrogenation of paraffins, containing: a carrier containing eta-alumina; from 0.1 to 10 wt.% of at least one component in the form of a rare earth metal; from 0.1 to 5 wt.% of at least one component containing an alkali metal; And from 17 to 40 wt.% chromium component; this is aluminum oxide the rest, wherein at least one alkali metal component contains a compound of sodium, potassium, rubidium, or combinations thereof.

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