WO2022169470A1

WO2022169470A1 - Enhanced methods for cracking c4-c6 organic molecules

Info

Publication number: WO2022169470A1
Application number: PCT/US2021/025944
Authority: WO
Inventors: Mohammed Abdulmajeed Al-Daous; Hussam A. Bahlouli
Original assignee: Saudi Arabian Oil Company; Aramco Services Company
Priority date: 2021-02-04
Filing date: 2021-04-06
Publication date: 2022-08-11

Abstract

According to the subject matter of the present disclosure, a process for cracking small molecules may comprise introducing a hydrocarbon vapor into a catalytic reactor; introducing hydrogen gas into the catalytic reactor; introducing a diluent gas into the catalytic reactor; forming a reaction mixture comprising the hydrocarbon vapor, the hydrogen gas, and the diluent gas; and contacting the reaction mixture with a cracking catalyst to produce a cracked hydrocarbon vapor. The reaction mixture may comprise from 5 vol. % to 20 vol. % C4-C6 hydrocarbons. The diluent gas may comprise one or more inert gases. The cracking catalyst may comprise ZSM-5 with a silica/alumina molar ratio of from 23 to 80.

Description

ENHANCED METHODS FOR CRACKING C₄-C₆ ORGANIC MOLECULES

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Application Serial No. 17/167,444 filed February 4, 2021, the entire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

[0002] The present disclosure relates to the cracking of small organic molecules and more specifically, to the cracking of C4-C6 organic molecules.

BACKGROUND

[0003] Light olefins (ethylene, propylene, and butenes) and light mono-aromatics (such as benzene, toluene, and xylenes) are the main building blocks of the petrochemical industry. They are produced on the scale of hundreds of millions of metric tons per year for use in chemical industries, including pharmaceuticals, plastics, optics, food, and dyes. Both ethylene and propylene are important building blocks for other chemicals, with around 70 % of each being used for polyethylene and polypropylene production, respectively.

[0004] Currently, the cheapest process to produce propylene is fluidized catalytic cracking (FCC) while the cheapest process to produce ethylene is steam cracking. Specifically, ethylene is produced mainly through steam cracking of ethane, steam cracking of naphtha, or gas-oil catalytic cracking. Light aromatics are traditionally produced by the catalytic reforming of naphtha. However, recently naphtha has been in short supply in some regions.

[0005] Saturated C4-C6 hydrocarbons can potentially be used to produce light olefins and light aromatics. The catalytic conversion of C4-C6 hydrocarbons offers an alternative to steam cracking to produce light olefins and aromatics. In particular, since C4 (butane) fractions are traditionally used as liquefied petroleum gas (LPG), an inexpensive supply of butane fractions is readily available. Therefore, the C4 fraction has become an attractive feed for cracking processes.

[0006] Catalytic cracking of saturated hydrocarbons is a complicated reaction that is not very selective to the production of the desired product. Numerous side reactions occur along with the main cracking reaction. Some of these side reactions are dehydrogenation, aromatization and hydride transfer. Together, these side reactions can consume significant portions of the hydrocarbon feed. Additionally, the side reactions may result in coke formation, which can deactivate the catalyst.

[0007] Accordingly, new methods are desired which can efficiently covert C4 to C'e hydrocarbons into light olefins and light aromatics, specifically light mono-aromatics, while minimizing side reactions and coke formation.

SUMMARY

[0008] Embodiments of the present disclosure meet this need by efficiently converting C4-C6 hydrocarbons into light olefins while minimizing side reactions and coke formation. Specifically, embodiments meet this need by contacting a C4to CT hydrocarbon vapor with hydrogen, a diluent gas, and a ZSM-5 catalyst with a silica/alumina molar ratio of from 23 to 80.

[0009] According to the one embodiment of the present disclosure, a process for cracking small molecules may comprise introducing a hydrocarbon vapor into a catalytic reactor; introducing hydrogen gas into the catalytic reactor; introducing a diluent gas into the catalytic reactor; forming a reaction mixture comprising the hydrocarbon, the hydrogen gas, and the diluent gas; and contacting the reaction mixture with a cracking catalyst to produce a cracked hydrocarbon vapor. The reaction mixture may comprise from 5 vol. % to 20 vol. % of hydrocarbon vapor. The diluent gas may comprise one or more inert gases. The cracking catalyst may comprise ZSM-5 with a silica/alumina molar ratio of from 23 to 80.

[0010] Although the concepts of the present disclosure are described herein with primary reference to the cracking of C4 to CT organic molecules, it is contemplated that the concepts will enjoy applicability to any upgrading of organic molecules.

ABBREVIATIONS

[0011] °C = degrees Celsius.

[0012] Min. = minute.

[0013] Hr. = hour.

[0014] cm³/min = cubic centimeters per minute. [0015] WHSV = weight hour space velocity.

[0016] h'¹ = 1/hour.

[0017] Vol. % = volume percent.

[0018] mol. % = mole percent.

[0019] C_x = carbon chains of x length.

[0020] ml min'¹ = milliliters per minute.

DETAILED DESCRIPTION

[0021] Embodiments of the present disclosure produce light olefins and light aromatics by efficiently converting C4 to CT hydrocarbons while minimizing side reactions and coke formation. Specifically, this is accomplished by contacting a hydrocarbon with hydrogen, a diluent gas, and a ZSM-5 catalyst with a silica/alumina molar ratio of from 23 to 80.

[0022] According to the subject matter of the present disclosure, a process for cracking small molecules may comprise introducing a hydrocarbon vapor into a catalytic reactor; introducing hydrogen gas into the catalytic reactor; introducing a diluent gas into the catalytic reactor; forming a reaction mixture comprising the hydrocarbon, the hydrogen gas, and the diluent gas; and contacting the reaction mixture with a cracking catalyst to produce a cracked hydrocarbon. The reaction mixture may comprise from 5 vol. % to 20 vol. % of hydrocarbon. The diluent gas may comprise one or more inert gases. The cracking catalyst may comprise ZSM-5 with a silica/alumina molar ratio of from 23 to 80.

[0023] The catalytic reactor may be any reactor configured to hold a cracking catalyst and to sustain a cracking reaction. For example, the cracking reactor may be a fixed-bed reactor, a fluidized bed reactor, or a moving bed reactor. A fixed-bed reactor may refer to a reactor in which the catalyst does not move during the catalytic reaction. A moving-bed reactor may refer to a reactor in which the catalyst is constantly flowing through the reactor along with the reactants. A fluidized-bed reactor may refer to a reactor in which the catalyst is suspended in the reactant gas. [0024] According to some specific embodiments, the catalytic reactor may be a fixed-bed reactor. It is believed that the present method may enable the use of fixed-bed reactors by decreasing coke formation and catalyst fouling, relative to conventional methods.

[0025] A hydrocarbon in the form of gas or vapor may be introduced into the catalytic reactor. As used herein, “hydrocarbon vapor” means hydrocarbon in the gas phase. The hydrocarbon may be introduced into the catalytic reactor in combination with a hydrogen gas and a diluent gas to form a reaction mixture.

[0026] The hydrocarbon may comprise at least 95 wt. % of C4to CT hydrocarbons. For example, the hydrocarbon may be at least 95 wt. %, at least 99 wt. %, or even at least 99.9 wt. % of C4 to CT hydrocarbons. At least 95 wt. % of the C4-C hydrocarbons may be alkanes. For example, at least 95 wt. %, at least 99 wt. %, or even at least 99 wt. % of the C4 to CT hydrocarbons may be alkanes.

[0027] A diluent gas may be introduced into the catalytic reactor. The diluent gas may comprise one or more inert gasses. The inert gas may comprise nitrogen, argon, helium, or a combination of these. The diluent gas may be at least 80 vol. %, at least 90 vol. %, at least 99 vol. %, or even greater than 99.9 vol. % inert gas. Without being limited to theory, dilute reactant hydrocarbon may be possible in order to reduce side reactions such as hydride transfer reaction. The diluent gas may be at least 80 vol. %, at least 90 vol. %, at least 99 vol. %, or even greater than 99.9 vol. % nitrogen.

[0028] Combining the hydrocarbon vapor, the hydrogen gas, and the diluent gas may form a reaction mixture. Without being limited by theory, the composition of the reaction mixture is believed to have a significant effect on the concentrations of ethylene, propylene, butenes, and aromatics in the cracked hydrocarbon produced. The compositions of the reaction mixtures of the present method may enable at least 80 % conversion and increased selectivity for light olefins and aromatics. According to some embodiments, the reaction mixture may consist of hydrocarbon vapor, hydrogen gas, and diluent gas.

[0029] The reaction mixture may comprise from 5 vol. % to 20 vol. % of hydrocarbon vapor. For example, the reaction mixture may comprise from 5 vol. % to 15 vol. %, from 10 vol. % to 20 vol. %, from 10 vol. % to 15 vol. %, or from 12 vol. % to 15 vol. % of the hydrocarbon vapor. According to some embodiments, the reaction mixture may comprise about 12.5 vol. % of the hydrocarbon vapor.

[0030] The reaction mixture may comprise from 2 vol. % to 85 vol. % of hydrogen gas. For example, the reaction mixture may comprise from 2 vol. % to 75 vol. %, from 2 vol. % to 60 vol. %, from 2 vol. % to 45 vol. %, from 2 vol. % to 30 vol. %, from 2 vol. % to 15 vol. %, 5 vol. % to 75 vol. %, from 5 vol. % to 60 vol. %, from 5 vol. % to 45 vol. %, from 5 vol. % to 30 vol. %, from 5 vol. % to 15 vol. %, 10 vol. % to 85 vol. %, 10 vol. % to 75 vol. %, from 10 vol. % to 60 vol. %, from 10 vol. % to 45 vol. %, from 10 vol. % to 30 vol. %, from 10 vol. % to 15 vol. %, from 20 vol. % to 85 vol. %, from 20 vol. % to 75 vol. %, from 20 vol. % to 60 vol. %, from 20 vol. % to 45 vol. %, from 20 vol. % to 30 vol. %, 30 vol. % to 75 vol. %, from 30 vol. % to 60 vol. %, from 30 vol. % to 45 vol. %, from 45 vol. % to 85 vol. %, from 45 vol. % to 75 vol. %, from 45 vol. % to 60 vol. %, or any subset thereof, of hydrogen.

[0031] Without being limited by theory, it is believed that the presence of hydrogen gas in the reaction mixture may keep the catalyst from being deactivated. It is believed that when hydrogen is consumed on the surface of the catalyst, for example through the hydrocarbon conversion reaction, the reaction will generate additional gas-phase hydrogen in order to establish an equilibrium between surface-adsorbed and gas-phase hydrogen. This behavior is believed to cause side-reactions which lead to coke formation. Thus, the presence of a sufficient amount of hydrogen in the feed stream will establish a more favorable equilibrium between gas-phase hydrogen and hydrogen adsorbed on the catalyst surface.

[0032] The reaction mixture may comprise from 1 vol. % to 93 vol. % of diluent gas. For example, the reaction mixture may comprise from 1 vol. % to 75 vol. %, from 1 vol. % to 60 vol. %, from 1 vol. % to 45 vol. %, from 1 vol. % to 30 vol. %, from 1 vol. % to 15 vol. %, from 5 vol. % to 93 vol. %, from 5 vol. % to 75 vol. %, from 5 vol. % to 60 vol. %, from 5 vol. % to 45 vol. %, from 15 vol. % to 93 vol. %, from 15 vol. % to 75 vol. %, from 15 vol. % to 60 vol. %, from 15 vol. % to 45 vol. %, from 30 vol. % to 93 vol. %, from 30 vol. % to 60 vol. %, from 45 vol. % to 60 vol. %, or any subset thereof, of diluent gas.

[0033] A volume ratio of hydrogen gas:diluent gas in the reaction mixture may be from 73:1 to 2:72. For example, the volume ratio of hydrogen gas:diluent gas may be from 73:1 to 2:65, from 73:1 to 2:55, from 73:1 to 2:45, from 73:1 to 2:35, from 73:1 to 2:25, from 73:1 to 2:15, from 73:1 to 2:5, 60:1 to 2:65, from 60:1 to 2:55, from 60:1 to 2:45, from 60:1 to 2:35, from 60:1 to 2:25, from 60:1 to 2:15, from 60:1 to 2:5, 45:1 to 2:65, from 45:1 to 2:55, from 15:1 to 2:45, from 15:1 to 2:35, from 15:1 to 2:25, from 15:1 to 2:15, from 15:1 to 2:5, 1 :1 to 2:65, from 1 :1 to 2:55, from 1 :1 to 2:45, from 1 :1 to 2:35, from 1 :1 to 2:25, from 1 :1 to 2:15, from 1 :1 to 2:5, or any subset thereof. It is believed that the ratio of hydrogen gas:diluent gas may control the concentrations of ethylene, propylene, butenes, and aromatics in the cracked hydrocarbon vapor. Accordingly, the volume ratio of hydrogen gas:diluent gas should be carefully selected for the desired outcome.

[0034] Optionally, the reaction mixture may comprise steam. In embodiments where the reaction mixture comprises steam, the reaction mixture may comprise from 0.0001 wt. % to 5 wt. % steam. For example, the reaction mixture may comprise from 0.0001 wt. % to 1 wt. %, or from 0.0001 wt. % to 0.01 wt. %, or from 0.0001 wt. % to 0.001 wt. %, or any subset thereof, of steam. Without being limited by theory, it is believed that the presence of steam may have a detrimental effect on the catalysts of the present disclosure.

[0035] The reaction mixture may contact a cracking catalyst to produce a cracked hydrocarbon vapor. The mixture may contact the cracking catalyst at a defined temperature, pressure, and weight hour space velocity (WHSV).

[0036] The reaction mixture may contact the cracking catalyst at a temperature of from 550 °C to 700 °C. For example, the reaction mixture may contact the cracking catalyst at a temperature of from 550 °C to 650 °C, from 600 °C to 700 °C, from 600 °C to 650 °C, from 625 °C to 700 °C, from 625 °C to 650 °C, or any subset thereof.

[0037] The reaction mixture may contact the cracking catalyst at a pressure of from 0.01 bar to 10 bar. For example, the reaction mixture may contact the cracking catalyst at a pressure of from 0.01 bar to 8 bar, from 0.01 bar to 6 bar, from 0.01 bar to 4 bar, from 0.01 bar to 2 bar, from 0.01 bar to 1 bar, from 0.1 bar to 8 bar, from 0.1 bar to 6 bar, from 0.1 bar to 4 bar, from 0.1 bar to 2 bar, from 0.1 bar to 1 bar, from 1 bar to 8 bar, from 1 bar to 6 bar, from 1 bar to 4 bar, from 1 bar to 2 bar, from 2 bar to 8 bar, from 2 bar to 6 bar, from 2 bar to 4 bar, or any subset thereof.

[0038] A weight hour space velocity (WHSV) of the process may be from 0.5 per hour (1T¹) to 4 h'¹. For example, the WHSV may be from 1 h'¹ to 4 h’¹, from 2 h'¹ to 4 h’¹, from 3 h'¹ to 4 h’¹, from 0.5 h'¹ to 3 h’¹, from 0.5 h'¹ to 2 h’¹, from 0.5 h'¹ to 1 h’¹, from 1 h'¹ to 3 h’¹, or any subset thereof. WHSV may be calculated as the - . For example, for a feed of 2 kilograms per hour weight of catalyst

(kg/h) hydrocarbon vapor and 1 kg cracking catalyst, the WHSV would be 2.

[0039] The cracking catalyst may comprise ZSM-5 with a silica/alumina molar ratio of from 23 to 80. For example, the silica/alumina molar ratio may be from 50 to 80. ZSM-5 may refer to a pentasil zeolite with channels defined by ten-membered rings. ZSM-5 may have a chemical formula of Na_nAl_nSi96-nOi92’ I6H2O (0<n<27).

[0040] Without being limited by theory, it is believed that the increased acidity and acid site density of the cracking catalyst will lead to increased activity of the cracking catalyst. Since the Si/Al ratio is believed to be the reciprocal of the number of acid sites in the zeolite, higher Si/Al ratios are expected to lead to decreased activity.

[0041] The ZSM-5 may be in hydrogen form. ZSM-5 is generally supplied in ammonium form and may need to be converted to hydrogen form before it is active as a cracking catalyst. The ZSM-5 may be converted to hydrogen form via calcination. For example, the ZSM-5 may be exposed to temperatures greater than 500 °C under an air or inert atmosphere, prior to contact with the reaction mixture.

[0042] The cracked hydrocarbon vapor may comprise one or more of methane, ethane, ethylene, propylene, butenes, pentanes, hexanes and aromatics. The butenes may comprise one or more of 1 -butene, cis-2-butene, trans-2-butene, and butadiene.

[0043] Without being limited by theory, it is believed that the methods of the present disclosure may enable extended operation of a fixed-bed reactor, relative to conventional methods. According to other embodiments, the reactor may be a moving-bed reactor or a fixed-bed reactor and the yield may be measured after 10 minutes to 8 hours, or after 30 minutes to 7 hours, or after 1 hours to 15 hours of contacting the cracking catalyst with the hydrocarbon vapor.

EXAMPLES

EXAMPLE 1 : Preparation of Catalyst A: ZSM-5(23)

[0044] Commercial ZSM-5 zeolite with a SiCh/AhCh ratio of 23 was supplied by Alfa Aesar in its ammonium form (NH^ /ZSM-5). The hydrogen form of the zeolite catalyst was obtained by calcining the received ammonium form using the following thermal treatment regime, under static air: the temperature was raised from room temperature to 120 °C at a ramp rate of 5 °C/min. The temperature was then held at 120 °C for 3 hours. After the three hours, the temperature was raised from 120 °C to 600 °C at a ramp rate of 2 °C/min. Finally, the temperature was held at 600 °C for 7 hours. The calcined product is referred to herein as Catalyst A or ZSM-5(23).

EXAMPLE 2: Preparation of Catalyst B: ZSM-5(50)

[0045] Commercial ZSM-5 zeolite with a SiCh/AhCh ratio of 50 was supplied by Alfa Aesar in its ammonium form (NH^ /ZSM-5). The hydrogen form of the zeolite catalyst was obtained by calcining the received ammonium form using the same thermal treatment regime as Example 1. The calcined product is referred to herein as catalyst B or ZSM-5(50).

EXAMPLE 3: Preparation of Catalyst C: ZSM-5(80)

[0046] Commercial ZSM-5 zeolite with a SiCh/AhCh ratio of 80 was supplied by Zeolyst in its ammonium form (NH^ /ZSM-5). The hydrogen form of the zeolite catalyst was obtained by calcining the received ammonium form using the same thermal treatment regime as Example 1. The calcined product is referred to herein as Catalyst C or ZSM-5(80).

EXAMPLE 4: Preparation of Comparative Catalyst D: ZSM-5(280)

[0047] Commercial ZSM-5 zeolite with SiCh/AhCL of 280 supplied by Zeolyst in its ammonium form (NH^ /ZSM-5). The hydrogen form of the zeolite catalyst was obtained by calcining the received ammonium form using the same thermal treatment regime as Example 1. The calcined product is referred to herein as Comparative Catalyst D or ZSM-5(280).

EXAMPLE 5: Catalyst Production, Treatment, and Activation

[0048] The catalysts of Examples 1 to 4 were pressed at 8 tons of pressure to form tablets, crushed, and sieved to form 200 to 500 micrometer granules. The granules (approx. 1.0 cm³, 0.5 grams) were packed into a tubular Hastelloy-X fixed-bed reactor which was 510 mm in length and with 5 mm internal diameter. The reactor had a thermocouple immersed into the catalyst bed.

[0049] A gas mixture of nitrogen (approx. 70 cm³/min.) and hydrogen (approx. 10 cm³/min.) was passed over the catalyst and the temperature was raised to 600 °C at the rate of 5 °C/min and kept at 600 °C for at least 1/2 hr. The temperature was then changed to the reaction temperature ranging from 625 °C to 650 °C at a rate of 5 °C/min. The gas mixture was changed to the one identified in Tables 1 to 4.

EXAMPLE 6: Catalyst Testing in Butane Cracking

[0050] Catalysts were used for a butane cracking reaction to produce lower olefins (ethylene, propylene, and butylene). Major side products included propane, ethane, methane, and aromatics.

[0051] The activity values listed in Tables 1 - 4 were measured after 6 hours on stream, with a weight hour space velocity (WHSV) of 2 h’¹, at atmospheric pressure, and 0.5 grams of catalyst at reaction temperatures of 625 °C and 650 °C. The feed stream contained 12.5 vol. % butane (30 vol. % iso-butane and 70 vol. % n-butane), hydrogen, and nitrogen with the nitrogen and hydrogen composition ratios listed in the tables.

[0052] As used in the tables “butane” refers to iso-butane and n-butane; “butenes” refers to 1- butene, cis-2-butene, trans-2-butene, and butadiene; and “aromatics” refers to benzene, toluene, and xylenes (BTX).

Table 1: Activity of butane cracking reaction over Catalyst A.

Table 2: Activity of butane cracking reaction over Catalyst B.

Table 3: Activity of butane cracking reaction over Catalyst C.

Table 4: Activity of butane cracking reaction over Comparative Catalyst D.

[0053] When using Catalysts A, B, and C, the yield of ethylene and propylene was found to increase with increasing hydrogen content in the feed stream. In contrast, when using Comparative Catalyst D, increasing hydrogen content led to decreasing yields of ethylene and propylene, and poor conversion of butane due to differences in acid site densities.

[0054] The maximum combined yield of propylene plus ethylene of 46.4 % was obtained over catalyst C when used hydrogen to nitrogen flow ratio of 30:34 ml min'¹ at 650 °C. [0055] It should be understood that the ranges used herein are inclusive. For example, a silica/alumina molar ratio of 50 or 80 is included within the range from 50 to 80.

[0056] A first aspect of the present disclosure may be directed to a process for cracking small molecules comprising: introducing a hydrocarbon vapor into a catalytic reactor; introducing hydrogen gas into the catalytic reactor; introducing a diluent gas into the catalytic reactor; forming a reaction mixture comprising the hydrocarbon vapor, the hydrogen gas, and the diluent gas; and contacting the reaction mixture with a cracking catalyst to produce a cracked hydrocarbon vapor; wherein: the reaction mixture comprises from 5 vol. % to 20 vol. % of hydrocarbon vapor, the hydrocarbon vapor comprises at least 12 vol. % of C4-C6 hydrocarbons, the diluent gas comprises one or more inert gasses, and the cracking catalyst comprises ZSM-5 with a silica/alumina molar ratio of from 23 to 80.

[0057] A second aspect of the present disclosure may include the first aspect, wherein the reaction mixture comprises from 2 vol. % to 85 vol. % of hydrogen gas.

[0058] A third aspect of the present disclosure may include either one of the first or second aspects, wherein the reaction mixture comprises from 1 vol. % to 93 vol. % of diluent gas.

[0059] A fourth aspect of the present disclosure may include any one of the first through third aspects, wherein a volume ratio of hydrogen gas:diluent gas in the reaction mixture is from 73:1 to 1 :72.

[0060] A fifth aspect of the present disclosure may include any one of the first through fourth aspects, wherein the hydrocarbon vapor comprises at least 99 wt. % of saturated hydrocarbons.

[0061] A sixth aspect of the present disclosure may include any one of the first through fifth aspects, wherein the ZSM-5 is in hydrogen form.

[0062] A seventh aspect of the present disclosure may include any one of the first through sixth aspects, wherein the reaction mixture contacts the cracking catalyst at a temperature of from 550 °C to 700 °C.

[0063] An eighth aspect of the present disclosure may include any one of the first through seventh aspects, wherein the reaction mixture contacts the cracking catalyst at a pressure of from 0.01 bar to 10 bar. [0064] A ninth aspect of the present disclosure may include any one of the first through eighth aspects, wherein a weight hour space velocity (WHSV) is from 0.5 per hour (h^-1) to 4 h’¹.

[0065] A tenth aspect of the present disclosure may include any one of the first through ninth aspects, wherein the cracked hydrocarbon vapor comprises one or more of ethylene, propylene, and butenes.

[0066] An eleventh aspect of the present disclosure may include any one of the first through tenth aspects, wherein the cracked hydrocarbon vapor comprises at least 5 mol. % of propylene.

[0067] A twelfth aspect of the present disclosure may include any one of the first through eleventh aspects, wherein the cracked hydrocarbon vapor comprises at least 12 mol. % of ethylene.

[0068] A thirteenth aspect of the present disclosure may include any one of the first through twelfth aspects, wherein the cracked hydrocarbon vapor comprises at least 1 mol. % of butenes.

[0069] A fourteenth aspect of the present disclosure may include any one of the first through thirteenth aspects, wherein the cracked hydrocarbon vapor comprises from 0.01 mol. % to 62 mol. % of aromatics, and wherein the aromatics comprise benzene, toluene, and xylenes.

[0070] A fifteenth aspect of the present disclosure may include any one of the first through fourteenth aspects, wherein the catalytic reactor is a fixed-bed reactor.

[0071] It is also noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc.

[0072] Having described the subject matter of the present disclosure in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Further, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including, but not limited to, embodiments defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

[0073] It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present invention, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”

Claims

1. A process for cracking small molecules comprising: introducing a hydrocarbon vapor into a catalytic reactor; introducing hydrogen gas into the catalytic reactor; introducing a diluent gas into the catalytic reactor; forming a reaction mixture comprising the hydrocarbon vapor, the hydrogen gas, and the diluent gas; and contacting the reaction mixture with a cracking catalyst to produce a cracked hydrocarbon vapor; wherein: the reaction mixture comprises from 5 vol. % to 20 vol. % of hydrocarbon vapor, the hydrocarbon vapor comprises at least 12 vol. % of C4-C6 hydrocarbons, the diluent gas comprises one or more inert gasses, and the cracking catalyst comprises ZSM-5 with a silica/alumina molar ratio of from 23 to 80.

2. The process of claim 1, wherein the reaction mixture comprises from 2 vol. % to 85 vol. % of hydrogen gas.

3. The process of either one of claim 1 or claim 2, wherein the reaction mixture comprises from 1 vol. % to 93 vol. % of diluent gas.

4. The process of any one of the preceding claims, wherein a volume ratio of hydrogen gas:diluent gas in the reaction mixture is from 73: 1 to 1 :72.

5. The process of any one of the preceding claims, wherein the hydrocarbon vapor comprises at least 99 wt. % of saturated hydrocarbons.

6. The process of any one of the preceding claims, wherein the ZSM-5 is in hydrogen form.

7. The process of any one of the preceding claims, wherein the reaction mixture contacts the cracking catalyst at a temperature of from 550 °C to 700 °C.

8. The process of any one of the preceding claims, wherein the reaction mixture contacts the cracking catalyst at a pressure of from 0.01 bar to 10 bar.

9. The process of any one of the preceding claims, wherein a weight hour space velocity (WHSV) is from 0.5 per hour (h’¹) to 4 h'¹.

10. The process of any one of the preceding claims, wherein the cracked hydrocarbon vapor comprises one or more of ethylene, propylene, and butenes.

11. The process of any one of the preceding claims, wherein the cracked hydrocarbon vapor comprises at least 5 mol. % of propylene.

12. The process of any one of the preceding claims, wherein the cracked hydrocarbon vapor comprises at least 12 mol. % of ethylene.

13. The process of any one of the preceding claims, wherein the cracked hydrocarbon vapor comprises at least 1 mol. % of butenes.

14. The process of any one of the preceding claims, wherein the cracked hydrocarbon vapor comprises from 0.01 mol. % to 62 mol. % of aromatics, and wherein the aromatics comprise benzene, toluene, and xylenes.

15. The process of any one of the preceding claims, wherein the catalytic reactor is a fixed-bed reactor.