Dehydrogenation catalyst with optimal modifier distribution index

Abstract

Catalysts and methods for selective conversion of hydrocarbons are provided. The catalyst comprises a first component selected from group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, and a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a support forming a catalyst particle comprising a plurality of pores. The catalyst has a modifier distribution index throughout the catalyst particles in the range of from 1 to 1.4.

Description

[0001] This application is a divisional application of the application with application number 202080021049.9, application date March 16, 2020, and invention name “Dehydrogenation catalyst with optimal modifier distribution index”. Background Art

[0002] Hydrocarbon dehydrogenation is an important commercial hydrocarbon conversion process due to the existing growing demand for dehydrogenated hydrocarbons used to make various chemical products such as detergents, high-octane gasoline, oxygenated gasoline blending components, pharmaceutical products, plastics, synthetic rubbers, and other products well known to those skilled in the art. The process for converting paraffins to olefins involves passing a paraffin stream over a highly selective catalyst, wherein the paraffin is dehydrogenated to the corresponding olefin. The dehydrogenation reaction is carried out under operating conditions selected to minimize feedstock losses. Typical methods involve the use of a reactor (e.g., a radial flow reactor, a fixed bed reactor, a fluidized bed reactor, etc.) in which the paraffin feed is contacted with a dehydrogenation catalyst under reaction conditions. An example of this method is the dehydrogenation of isobutane to produce isobutylene, which can be polymerized to provide a tackifier for adhesives, a viscosity index additive for motor oils, and an impact and antioxidant additive for plastics. There is also a growing demand for isobutylene, which is used to produce government-mandated oxygenated gasoline blending components to reduce air pollution from motor vehicle emissions.

[0003] Those skilled in the art of hydrocarbon conversion processing are familiar with the production of olefins by catalytic dehydrogenation of paraffins. In addition, many patents have been published that generally teach and discuss the dehydrogenation of hydrocarbons. For example, U.S. Patent No. 4,430,517 (Imai et al.), U.S. Patent No. 4,438,288 (Imai et al.) and U.S. Patent No. 6,756,340 (Voskoboynikov et al.) discuss dehydrogenation methods and catalysts used therein. However, there is still a continuous need for new catalytic materials for selective hydrocarbon conversion processes, particularly those catalytic materials that can improve one or more characteristics of known catalytic compositions. Summary of the invention

[0004] The present invention provides a catalyst for selective conversion of hydrocarbons. The catalyst comprises: a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, and a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a carrier, the carrier forming catalyst particles comprising a plurality of pores. The catalyst has a modifier distribution index in the range of 1 to 1.4 over the entire catalyst particle. The catalyst may have a modifier distribution index in the range of 1 to 1.2 or in the range of 1 to 1.1.

[0005] The catalyst may comprise a first component (which is platinum), a potassium modifier, and tin (which is a third component). The carrier may be silica, alumina, silica-alumina, zeolite, non-zeolitic molecular sieve, titania, zirconia or a mixture thereof. The catalyst particles may be spherical.

[0006] The present invention provides a method for selectively converting hydrocarbons, wherein the method comprises contacting the hydrocarbons with a catalytic composite material under selective conversion conditions, the catalytic composite material comprising a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a support, the support forming a catalyst particle, wherein the catalyst has a modifier distribution index in the range of 1 to 1.4 throughout the catalyst particle. The method can produce more isobutylene than a method using a catalyst having a modifier distribution index greater than 1.4, and in some cases, the method can produce at least 1% more isobutylene product than a method using a catalyst having a modifier distribution index greater than 1.4. The method can produce fewer normal paraffin and olefin products than a method using a catalyst having a modifier distribution index greater than 1.4, and in some cases, the method can produce at least 10% less normal paraffin and olefin products than a method using a catalyst having a modifier distribution index greater than 1.4. The modifier distribution index of the catalyst can be in the range of 1 to 1.2 or 1 to 1.1.

[0007] In the method, the catalyst may have a first component (which is platinum), a modifier (which is potassium), and a third component (which is tin). The carrier may be selected from silica, alumina, silica alumina, zeolite, non-zeolitic molecular sieves, titanium dioxide, zirconium oxide and mixtures thereof. The catalyst particles may be spherical. The hydrocarbon may include at least one alkane having 2 to 30 carbon atoms. The hydrocarbon may include at least one alkane having 2 to 6 carbon atoms. The hydrocarbon may include at least one alkane having 3 to 4 carbon atoms. The method may also include at least one of the following items: sensing at least one parameter of the method and generating a signal or data by the sensing; generating and transmitting a signal; or generating and transmitting data. DETAILED DESCRIPTION

[0008] Surprisingly, it has been found that the dehydrogenation catalyst has an optimal modifier distribution index (MPI) in a relatively wide range of 1-1.4. Catalysts with MPI=1-1.4 make less coke in propane and isobutane dehydrogenation operations, are more selective to isobutene, and make normal paraffin and olefin products in isobutane operations less annoying. Surprisingly, there seems to be an optimal range of MPI in a relatively wide range of 1-1.4, rather than an optimal discrete MPI value. Surprisingly, for MPI>1.4, there seems to be a step change in isobutene selectivity and isomerization to normal paraffin and olefin products. The alumina support has Lewis acid sites that are active for isomerization reactions and acid cracking reactions. The role of the modifier is to quench the residual acidity and minimize and / or eliminate those undesirable reactions. Without being bound by theory, it seems that an MPI in the range of 1-1.4 provides the catalyst with a desired modifier distribution over the entire catalyst pellet. When the MPI is less than 1 or greater than 1.4, residual alumina acid sites located toward the edge or center of the catalyst pellet, respectively, remain available for isomerization and cracking reactions.

[0009] Dehydrogenation catalysts having a modifier distribution index in the range of 1 to 1.4 can be manufactured using several formulations. From a manufacturing perspective, it is advantageous that the MPI is optimal over a relatively wide range, rather than an optimal discrete value near 1, because this provides greater flexibility in the impregnation and drying times used in catalyst manufacturing. The catalyst can be used to maximize isobutylene production and minimize isomerization to undesirable linear alkane and olefin products in an isobutane or mixed isobutane and propane dehydrogenation operation.

[0010] One aspect of the present invention is a catalyst for selectively converting hydrocarbons. In one embodiment, the catalyst comprises: a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, and a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a carrier, the carrier forming a catalyst particle comprising a plurality of pores. The catalyst has a modifier distribution index in the range of 1 to 1.4 throughout the catalyst particle.

[0011] The modifier distribution index is calculated by scanning electron microscope (SEM) energy dispersive spectrum (EDS) analysis of at least 12 separate catalyst pellets. On JEOL 7800 with Oxford Aztec EDS system, 30kV accelerating voltage is used to collect SEM metal concentration distribution. Each point in the metal concentration distribution is calculated using the average value of the analysis point at a constant distance from the edge of the pellet in the catalyst cross section. This is performed to produce a concentration distribution for a series of distances. Then MPI is calculated by the distribution of all catalyst pellets analyzed. For example, for 1.6mm catalyst pellets, MPI is the average modifier concentration at the edge (arbitrarily defined as 0-200 microns) of all analyzed catalyst pellets and the average modifier concentration at the center (arbitrarily defined as 500-700 microns) of all analyzed catalyst pellets.

[0012] In some embodiments, the modifier distribution index is in the range of 1 to 1.2. In some embodiments, the modifier distribution index is in the range of 1 to 1.1.

[0013] In some embodiments, the first component is platinum, the modifier is potassium, and the third component is tin.

[0014] In some embodiments, the support is selected from the group consisting of silica, alumina, silica-alumina, zeolites, non-zeolitic molecular sieves, titania, zirconia, and mixtures thereof.

[0015] In some embodiments, the catalyst particles are spherical.

[0016] Another aspect of the invention is a method for selectively converting hydrocarbons. In one embodiment, the method comprises contacting the hydrocarbons under selective conversion conditions with a catalytic composite material comprising a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a support, the support forming catalyst particles, wherein the catalyst has a modifier distribution index throughout the catalyst particles in the range of 1 to 1.4.

[0017] In some embodiments, the process produces more isobutylene than a process using a catalyst having a modifier distribution index greater than 1.4.

[0018] In some embodiments, the process produces at least 1% more isobutylene product than a process using a catalyst having a modifier distribution index greater than 1.4.

[0019] In some embodiments, the process produces less normal paraffin and olefin products than a process using a catalyst having a modifier distribution index greater than 1.4.

[0020] In some embodiments, the process produces at least 10% less normal paraffin and olefin products than a process using a catalyst having a modifier distribution index greater than 1.4.

[0021] In some embodiments, the modifier distribution index is in the range of 1 to 1.2. In some embodiments, the modifier distribution index is in the range of 1 to 1.1.

[0022] In some embodiments, the first component is platinum, the modifier is potassium, and the third component is tin.

[0023] In some embodiments, the support is selected from the group consisting of silica, alumina, silica-alumina, zeolites, non-zeolitic molecular sieves, titania, zirconia, and mixtures thereof.

[0024] In some embodiments, the catalyst particles are spherical.

[0025] In some embodiments, the hydrocarbon comprises at least one paraffin having 2 to 30 carbon atoms. In some embodiments, the hydrocarbon comprises at least one paraffin having 2 to 6 carbon atoms. In some embodiments, the hydrocarbon comprises at least one paraffin having 3 to 4 carbon atoms.

[0026] In some embodiments, the method further comprises at least one of: sensing at least one parameter of the method and generating a signal or data from the sensing; generating and transmitting a signal; or generating and transmitting data.

[0027] In one embodiment, the catalyst is platinum, tin, potassium on a spherical alumina porous support having an optimal MPI across the entire catalyst pellet. In one embodiment, the catalyst can be used for the dehydrogenation of propane, isobutane, or a mixed propane and isobutane feed.

[0028] Depending on the recipe used to make the catalyst, the modifier distribution across the catalyst pellet can be flat (MPI=1) or skewed with higher modifier concentrations at the edge of the pellet.MPI is calculated using modifier concentrations measured via SEM-EDS analysis (Scanning Electron Microscope Energy Dispersive Spectroscopy).

[0029] The dehydrogenation of paraffins is well known to those skilled in the art of hydrocarbon processing. In a dehydrogenation zone maintained under dehydrogenation conditions, a dehydrogenatable hydrocarbon is contacted with a dehydrogenation catalyst. The contact can be achieved in a fixed catalyst bed system, a mobile catalyst bed system, a fluidized bed system, etc., or in intermittent operation. The dehydrogenation zone may include one or more independent reaction zones, with heating components between the reaction zones to ensure that the desired reaction temperature can be maintained at the entrance of each reaction zone. The hydrocarbons can be contacted with the catalyst bed in an upward, downward or radial flow flow mode. The radial flow of hydrocarbons through the catalyst bed is preferred for a mobile catalyst bed system. The radial flow reactor is configured so that the reactor has an annular structure and an annular distribution and a collection device. The device for distribution and collection combines some types of screen-type surfaces. The screen-type surface is used to keep the catalyst bed in place and contribute to the pressure distribution on the reactor surface to facilitate radial flow through the reactor bed. The screen can be a mesh of wire or other material, or a perforated plate. For a moving bed, the screen or mesh provides a barrier to prevent the loss of solid catalyst particles while allowing fluid to flow through the bed. Solid catalyst particles are added at the top, flow through the device, and removed at the bottom while passing through a closed housing that allows fluid to flow through the catalyst. Screens are described, for example, in U.S. Pat. No. 9,266,079 and U.S. Pat. No. 9,433,909 (Vetter et al.).

[0030] Dehydrogenatable hydrocarbons include dehydrogenatable hydrocarbons having 2 to 30 or more carbon atoms, including paraffins, alkyl aromatics, cycloalkanes and olefins. One group of hydrocarbons that can be dehydrogenated with the catalyst is the group of paraffins having 2 to 30 or more carbon atoms. The catalyst is particularly useful for dehydrogenating paraffins having 2 to 15 or more carbon atoms to the corresponding monoolefins or for dehydrogenating monoolefins having 3 to 15 or more carbon atoms to the corresponding dienes. The catalyst is particularly useful for dehydrogenating C2-C6 paraffins (mainly propane, isobutane, or a mixture of propane and isobutane) to monoolefins.

[0031] The dehydrogenation conditions include a temperature of 400°C to 900°C, a pressure of 0.01 to 10 atmospheres absolute, and a pressure of 0.1 hr. -1 Up to 100hr -1 The liquid hourly space velocity (LHSV) of the dehydrogenation zone is preferably about 100 mol / l. Generally, for normal paraffins, the lower the molecular weight, the higher the temperature required to achieve comparable conversion. The pressure in the dehydrogenation zone is maintained as low as practicable, consistent with equipment limitations, to maximize chemical equilibrium advantages.

[0032] The effluent stream from the dehydrogenation zone will usually contain unconverted dehydrogenatable hydrocarbons, hydrogen and the product of the dehydrogenation reaction. The effluent stream is usually cooled, optionally compressed and sent to a hydrogen separation zone to separate the hydrogen-rich gas phase from the hydrocarbon-rich liquid phase. Usually, the hydrocarbon-rich liquid phase is further separated by a suitable selective adsorbent, a selective solvent, one or more selective reactions or by a suitable fractionation scheme. Unconverted dehydrogenatable hydrocarbons are recovered and can be recycled to the dehydrogenation zone. The product of the dehydrogenation reaction is recovered as a final product or as an intermediate product for preparing other compounds.

[0033] In general, the dehydrogenation process may include one or more dehydrogenation reactors, fired heaters, heat exchangers, quench towers, compressors, cryogenic separation systems, processing systems, fuel gas preparation systems, light ends recovery systems, adsorption systems, fractionation towers, catalyst treatment / regeneration equipment, as known in the art and described in "Handbook of Petroleum Refining Process, 4th Edition, Chapter 4.1". th Further discussion is provided in "Edition, Chapter 4.1)".

[0034] Any of the above-mentioned pipelines, conduits, units, equipment, containers, surrounding environments, zones or the like may be equipped with one or more monitoring components, including sensors, measuring devices, data capture devices or data transmission devices. Signals, process or state measurements and data from monitoring components can be used to monitor conditions in, around and related to process equipment. Signals, measurements and / or data generated or recorded by monitoring components can be collected, processed and / or transmitted via one or more networks or connections, which can be private or public, general or dedicated, direct or indirect, wired or wireless, encrypted or unencrypted, and / or combinations thereof; the present specification is not intended to be limiting in this regard.

[0035] The signals, measurements and / or data generated or recorded by the monitoring components may be transmitted to one or more computing devices or systems. The computing device or system may include at least one processor and a memory storing computer-readable instructions, which, when executed by at least one processor, causes one or more computing devices to perform a process that may include one or more steps. For example, one or more computing devices may be configured to receive data related to at least one piece of equipment associated with the process from one or more monitoring components. One or more computing devices or systems may be configured to analyze the data. Based on the data analysis, one or more computing devices or systems may be configured to determine one or more recommended adjustments to one or more parameters of one or more processes described herein. One or more computing devices or systems may be configured to transmit encrypted or unencrypted data, which includes one or more recommended adjustments to one or more parameters of one or more processes described herein.

[0036] Example

[0037] Isobutane dehydrogenation

[0038] In order to demonstrate the advantages to be achieved by the present invention, several dehydrogenation catalysts with the same metal composition but different MPI were prepared and tested in a pilot plant. 3 ) to produce isobutylene on a stream (HOS) for 26 hours. The operating conditions for each pilot unit test included: pure isobutane feed, a hydrogen to feed ratio of 0.6, a liquid hourly space velocity (LHSV) of 11h -1 , pressure was 135 kPa (5 psig), feed temperature was 645°C, and hydrogen sulfide was 70 ppm.

[0039] It can be seen from Table 1 that, compared with catalysts A and B, the catalysts of the present invention having MPI=1-1.4 (catalysts C, D and E) have higher selectivity to isobutylene and lower isomerization to linear butane and butene.

[0040] Table 1: Selectivity to isobutene and isomerization to n-butane and n-butene at 55% isobutane conversion

[0041]

[0042] Specific implementation plan

[0043] While the following is described in conjunction with specific embodiments, it should be understood that this description is intended to illustrate and not to limit the scope of the foregoing description and the appended claims.

[0044] The first embodiment of the present invention is a catalyst for selective conversion of hydrocarbons, the catalyst comprising: a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, and a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a carrier, the carrier forming a catalyst particle comprising a plurality of pores, wherein the catalyst has a modifier distribution index in the range of 1 to 1.4 throughout the catalyst particle. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the modifier distribution index is in the range of 1 to 1.2. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the modifier distribution index is in the range of 1 to 1.1. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the first embodiment of this paragraph, wherein the first component is platinum, the modifier is potassium, and the third component is tin. An embodiment of the present invention is one, any or all of the previous embodiments in this paragraph through the first embodiment in this paragraph, wherein the support is selected from the group consisting of silica, alumina, silica alumina, zeolites, non-zeolitic molecular sieves, titania, zirconia and mixtures thereof. The catalyst of claim 1, wherein the catalyst particles are spherical.

[0045] A second embodiment of the invention is a method for selectively converting hydrocarbons, the method comprising contacting the hydrocarbons under selective conversion conditions with a catalytic composite material, the catalytic composite material comprising a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a support, the support forming catalyst particles, wherein the catalyst has a modifier distribution index in the range of 1 to 1.4 throughout the catalyst particles. An embodiment of the invention is one, any one or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, wherein the method produces more isobutylene than a method using a catalyst having a modifier distribution index greater than 1.4. An embodiment of the invention is one, any one or all of the previous embodiments in this paragraph to the second embodiment in this paragraph, wherein the method produces at least 1% more isobutylene product than a method using a catalyst having a modifier distribution index greater than 1.4. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the method produces less normal paraffin and olefin products than a method using a catalyst having a modifier distribution index greater than 1.4. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the method produces at least 10% less normal paraffin and olefin products than a method using a catalyst having a modifier distribution index greater than 1.4. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the modifier distribution index is in the range of 1 to 1.2. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the modifier distribution index is in the range of 1 to 1.1. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the first component is platinum, the modifier is potassium, and the third component is tin. One embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the carrier is selected from silica, alumina, silica-alumina, zeolite, non-zeolitic molecular sieve, titania, zirconium oxide and mixtures thereof. One embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the catalyst particles are spherical. One embodiment of the present invention is one, any or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the hydrocarbon comprises at least one paraffin having 2 to 30 carbon atoms.One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the hydrocarbon comprises at least one alkane having 2 to 6 carbon atoms. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, wherein the hydrocarbon comprises at least one alkane having 3 to 4 carbon atoms. One embodiment of the present invention is one, any one or all of the previous embodiments of this paragraph to the second embodiment of this paragraph, further comprising at least one of the following: sensing at least one parameter of the method and generating a signal or data from the sensing; generating and transmitting a signal; or generating and transmitting data.

[0046] Although there is no further detailed description, it is believed that those skilled in the art can utilize the present invention to the greatest extent by using the foregoing description and can easily determine the essential characteristics of the present invention without departing from the spirit and scope of the present invention to make various changes and modifications of the present invention and adapt it to various usages and conditions. Therefore, the aforementioned preferred specific embodiments should be understood as merely illustrative and not to limit the rest of the present disclosure in any way, and are intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[0047] In the foregoing, all temperatures are set forth in degrees Celsius and all parts and percentages are by weight unless otherwise indicated.

Claims

1. A catalyst for selectively converting hydrocarbons, the catalyst comprising: a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, and a third component selected from tin, germanium, lead, indium, gallium, thallium and mixtures thereof; and a carrier, the carrier forming a catalyst particle comprising a plurality of pores, wherein the catalyst has a modifier distribution index throughout the catalyst particles in the range of 1 to 1.

4.

2. The catalyst according to claim 1, wherein the modifier distribution index is in the range of 1 to 1.

1.

3. The catalyst of claim 1, wherein the first component is platinum, the modifier is potassium, and the third component is tin.

4. The catalyst according to claim 1, wherein the support is selected from the group consisting of silica, alumina, silica-alumina, zeolite, non-zeolitic molecular sieve, titania, zirconia and mixtures thereof.

5. A method for selectively converting hydrocarbons, the method comprising: contacting a hydrocarbon under selective conversion conditions with a catalytic composite material comprising a first component selected from Group VIII noble metals and mixtures thereof, a modifier selected from alkali metals or alkaline earth metals and mixtures thereof, a third component selected from the group consisting of tin, germanium, lead, indium, gallium, thallium, and mixtures thereof, and a carrier, said carrier forming catalyst particles, wherein the catalyst has a modifier distribution index throughout the catalyst particles in the range of 1 to 1.

4.

6. The process of claim 5, wherein the process produces at least 1% more isobutylene product than a process using a catalyst having a modifier distribution index greater than 1.

4.

7. The process of claim 5, wherein the process produces at least 10% less normal paraffin and olefin products than a process using a catalyst having a modifier distribution index greater than 1.

4.

8. The method of claim 5, wherein the modifier distribution index is in the range of 1 to 1.

1.

9. The method of claim 5, wherein the first component is platinum, the modifier is potassium, and the third component is tin.

10. The method of claim 5, wherein the support is selected from the group consisting of silica, alumina, silica-alumina, zeolites, non-zeolitic molecular sieves, titania, zirconia, and mixtures thereof.

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