Dry Reforming of Hydrocarbons

Abstract

A dry reforming method for producing synthesis gas from a hydrocarbon fuel is described. A feed stream is preheated. The feed stream includes a hydrocarbon fuel and carbon dioxide. The feed stream is flowed to a reactor. The reactor includes a catalyst. The feed stream is flowed to the reactor so that the feed stream contacts the catalyst in the absence of oxygen and causes a dry reforming reaction in the reactor for a period of time sufficient to reform the hydrocarbon fuel to produce synthesis gas. The catalyst includes nickel (Ni), lanthanum oxide (La2O3), cerium oxide (Ce2O3) and platinum (Pt).

Description

[0001] Priority declaration

[0002] This application claims priority to U.S. Patent Application No. 16 / 927,642, filed on July 13, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the reforming of hydrocarbons, and in particular to the dry reforming of hydrocarbons. Background Art

[0004] Synthesis gas, also known as synthesis gas, is a fuel gas mixture that includes hydrogen, carbon monoxide, and sometimes carbon dioxide. Synthesis gas is combustible and can be used as a fuel for internal combustion engines. In some cases, synthesis gas can be used as an intermediate for producing synthetic petroleum used as a fuel or lubricant. Synthesis gas can also be used to produce methanol or as a source of hydrogen for various processes. Hydrocarbon reforming is an example of a process for producing synthesis gas. Summary of the invention

[0005] This disclosure describes technologies related to hydrocarbon reforming.

[0006] Certain aspects of the present subject matter can be implemented as a dry reforming method for producing synthesis gas from hydrocarbon fuels. A feed stream is preheated. The feed stream includes a hydrocarbon fuel and carbon dioxide. The feed stream is flowed to a reactor. The reactor includes a catalyst. The feed stream is flowed to the reactor so that the feed stream is contacted with the catalyst in the absence of oxygen, and a dry reforming reaction is caused in the reactor for a period of time sufficient to reform the hydrocarbon fuel to produce synthesis gas. The catalyst includes nickel (Ni), lanthanum oxide (La2O3), cerium oxide (Ce2O3) and platinum (Pt).

[0007] This and other aspects may include one or more of the following features.

[0008] In some embodiments, the feed stream is preheated to a temperature in a range from about 750 degrees Celsius (°C) to about 950°C.

[0009] In some embodiments, during the dry reforming reaction, the operating pressure within the reactor is in the range of from about 7 bar to about 28 bar.

[0010] In some embodiments, the feed stream has a ratio of carbon dioxide to hydrocarbons in a range from about 1:1 to about 4:1.

[0011] In some embodiments, the feed stream has a carbon dioxide to hydrocarbon ratio in a range from about 1:1 to about 2:1.

[0012] In some embodiments, the feed stream includes water.

[0013] In some embodiments, the feed stream has a water to carbon ratio in a range from about 1:10 to about 3:1.

[0014] In some embodiments, the water to carbon ratio of the feed stream ranges from about 1:10 to about 1:1.

[0015] In some embodiments, the catalyst includes zirconium oxide (ZrO2), rhodium (Rh), rhenium (Re), and an aluminate support.

[0016] In some embodiments, the catalyst comprises about 0.5 weight percent (wt.%) to about 15 wt.% Ni, about 0.5 wt.% to about 10 wt.% Ce2O3, about 0.5 wt.% to about 5 wt.% La2O3, about 0.1 wt.% to about 2 wt.% Pt, up to about 1 wt.% ZrO2, up to about 2 wt.% Rh, and up to about 2 wt.% Re.

[0017] In some embodiments, potassium (K) is incorporated into the aluminate support.

[0018] In some embodiments, the catalyst comprises K in an amount of about 0.5 wt. % to about 5.0 wt. %.

[0019] The details of one or more implementations of the subject matter of the present disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A is a schematic diagram of an example system for dry reforming of hydrocarbons.

[0021] Figure 1B is a schematic diagram of an example system for dry reforming of hydrocarbons.

[0022] Figure 2 is a flow diagram of an example process for dry reforming of hydrocarbons.

[0023] Figure 3A-1 , 3A-2 , 3A-3 and 3A-4 are graphs showing the thermodynamic equilibrium product compositions of the dry reforming process.

[0024] Figure 3B-1 , 3B-2 and 3B-3 are graphs showing the effect of operating pressure on a dry reforming process.

[0025] Figure 3C-1 , 3C-2 and 3C-3 are graphs showing the effect of operating pressure on a dry reforming process.

[0026] Figure 3D-1 , 3D-2 and 3D-3 are graphs showing the effect of operating pressure on the dry reforming process.

[0027] Figure 3E-1 , 3E-2 and 3E-3 are graphs showing the effect of gas hourly space velocity on the dry reforming process.

[0028] Figure 3F-1 , 3F-2 and 3F-3 are graphs showing the effect of operating temperature on the dry reforming process.

[0029] Figure 3G-1 , 3G-2 and 3G-3 are graphs showing the effect of operating temperature on the dry reforming process. DETAILED DESCRIPTION

[0030] The present disclosure describes the reforming of hydrocarbons. The conversion of hydrocarbon fuels into hydrogen can be carried out by several processes, including hydrocarbon steam reforming, partial oxidation reforming, autothermal reforming and dry reforming. Hydrocarbon dry reforming includes the reaction of carbon dioxide (CO2) with a fuel (e.g., methane, CH4) in the presence of a catalyst and in the absence of oxygen to produce hydrogen (H2) and carbon monoxide (CO), as given by equation (1). The mixture of hydrogen and carbon monoxide can be referred to as synthesis gas (syngas). In some cases, synthesis gas also includes carbon dioxide.

[0031] CH4+CO2→2CO+2H2(ΔH 298K = +247 kJ·mol -1 ) (1)

[0032] The subject matter described in the present disclosure can be implemented in a specific embodiment to achieve one or more of the following advantages. Dry reforming produces hydrogen and carbon monoxide in a molar ratio of 1: 1, which is suitable for a wide variety of hydroformylation applications. About half of the carbon atoms in the synthesis gas obtained by the dry reforming method are derived from carbon dioxide rather than methane. Compared with other reforming processes (e.g., steam reforming in which all carbon atoms are derived from methane), this reduces the dependence of the dry reforming method on methane feedstock. In addition, carbon dioxide, a known greenhouse gas, is a feedstock for the dry reforming method to form useful products, rather than being discharged into the atmosphere, for example. The catalyst described herein exhibits resistance to coke formation and sintering, even under high temperature and high pressure conditions. The described method and catalyst can allow greenhouse gas emissions to be reduced in an economical manner. The described method can integrate renewable hydrogen into existing industrial processes and can reduce the carbon footprint of chemicals and fuels.

[0033] Although dry reforming is already known, currently known catalysts (e.g., nickel-alumina-based catalysts) may be deactivated due to excessive coke deposition and agglomeration (i.e., sintering) of metal particles at the high temperatures required for dry reforming, which may result in a reduction in the available surface area of ​​the catalyst. Sintering involves the agglomeration of small metal particles to form larger metal particles and results in a reduction in the active sites of the catalyst. Coking involves the cracking of carbonaceous compounds on the surface of the catalyst, which makes it selective for undesirable side reaction products and also results in a reduction in the active sites of the catalyst. Compared to nickel-based catalysts, catalysts based on Group VIII noble metals may be less sensitive to coking, but their formation costs may also be higher and may also be more prone to sintering. Certain noble metals, such as platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), and ruthenium (Ru) can exhibit favorable dry reforming activity while resisting deactivation caused by coking and sintering.

[0034] refer to Figure 1A , system 100 includes a feed stream 101, a preheater 103, and a reactor 105. The feed stream 101 includes a hydrocarbon fuel and carbon dioxide. The hydrocarbon fuel includes hydrocarbons such as methane, propane, butane, other hydrocarbons having up to 12 carbon atoms, or mixtures thereof. In some embodiments, the hydrocarbon fuel includes liquid hydrocarbons that have been vaporized. In some embodiments, the feed stream 101 has a ratio of carbon dioxide to hydrocarbons in a range from about 1:1 to about 4:1. In some embodiments, the feed stream 101 has a ratio of carbon dioxide to hydrocarbons in a range from about 1:1 to about 2:1. For example, the feed stream 101 has a ratio of carbon dioxide to methane in a range from about 1:1 to about 4:1 or from about 1:1 to about 2:1. The feed stream 101 does not contain oxygen (O2).

[0035] The feed stream 101 flows to the preheater 103. The preheater 103 is configured to preheat the feed stream 101. In some embodiments, the preheater 103 is configured to preheat the feed stream 101 to a temperature in the range of from about 700 degrees Celsius (°C) to about 950°C. In some embodiments, the preheater 103 is configured to preheat the feed stream 101 to a temperature in the range of from about 700°C to about 850°C. In some embodiments, the preheater 103 is configured to preheat the feed stream 101 to a temperature in the range of from about 750°C to about 950°C. Referring to equation (1), the dry reforming reaction is endothermic. In some embodiments, preheating the feed stream 101 to a temperature above 750°C can improve the selectivity for generating hydrogen and carbon monoxide (which are preferred products) and avoid the formation of other carbon-containing compounds. Preheating the feed stream 101 (eg, to a temperature above 750°C or above 800°C) can slow methane cracking both during the preheating process and in a dry operating mode (ie, without added steam) of the dry reforming process.

[0036] The preheated feed stream 104 leaves the preheater 103 and flows to the reactor 105. In some embodiments, the reactor 105 is a packed bed reactor. In some embodiments, the reactor 105 is a fluidized bed reactor. Within the reactor, methane reacts with carbon dioxide to produce synthesis gas 106 (carbon monoxide and hydrogen). In other words, the dry reforming reaction represented by equation (1) occurs within the reactor 105.

[0037] Reactor 105 includes a catalyst. The preheated feed stream 104 is flowed to reactor 105 to contact the preheated feed stream 104 with the catalyst. In the absence of oxygen, the catalyst accelerates and causes the dry reforming reaction in the reactor to continue for a period of time sufficient to reform the hydrocarbon fuel (e.g., methane) to produce synthesis gas 106. Because oxygen is not introduced into reactor 105, no combustion occurs in reactor 105. In some embodiments, during the dry reforming reaction, the operating pressure in reactor 105 is in the range of from about 7 bar to about 28 bar. On the one hand, since the volume of the product formed by the dry reforming reaction is greater than the volume of the reactant, in some cases, during the dry reforming reaction, a lower operating pressure in reactor 105 may be preferred. On the other hand, a higher operating pressure allows the production of the reactant to be processed in reactor 105 to increase, so in some cases, during the dry reforming reaction, a higher operating pressure in reactor 105 may be preferred. In some embodiments, the operating pressure in reactor 105 depends on the operating pressure of downstream operations (e.g., synthesis gas application or purification). For example, in applications where syngas is used to produce dimethyl ether (DME), the operating pressure of such applications is often higher, so the syngas produced from the reactor 105 can be compressed, and the operating pressure within the reactor 105 can be optimized to improve conversion at pressures greater than 10 bar. In some embodiments, coking becomes more significant at higher pressures, especially in the case where the dry reforming reaction is completely dry (i.e., no water in the form of steam is added), so under such conditions, during the dry reforming reaction, the operating pressure within the reactor 105 is in the range of from about 10 bar to about 15 bar. By adding water in the form of steam to the feed to the reactor 105, the range of operating pressures can be expanded. During the dry reforming reaction, the operating pressure within the reactor 105 can be determined based on one or more of the above factors and the economics of the process.

[0038] In some embodiments, the catalyst within the reactor 105 is pretreated. For example, the catalyst is preheated within the reactor 105 so that the catalyst is at a desired temperature before the feed stream 104 flows to the reactor 105. In some embodiments, the internal volume of the reactor 105 is preheated so that the operating temperature within the reactor 105 is at a desired temperature before the feed stream 104 flows to the reactor 105. In some embodiments, the desired temperature of the catalyst, the operating temperature within the reactor 105, or both are the same as or within a 10% deviation from the temperature at which the feed stream 104 is preheated in the preheater 103.

[0039] The catalyst includes rare earth metal oxides, such as lanthanum oxide (La2O3), cerium oxide (Ce2O3), or a mixture of the two. In some embodiments, the catalyst includes an oxide of a Group IV metal, such as zirconium oxide (ZrO2). In some embodiments, the catalyst includes nickel (Ni), a reducible compound of Ni (e.g., nickel oxide (NiO)), or a mixture of the two. In some embodiments, the catalyst includes a platinum group metal, such as platinum (Pt), Rh, or a mixture of the two. A platinum group metal in pure elemental form or as part of a compound comprising a platinum group metal may be included. In some embodiments, the catalyst includes a Group VIIB metal, such as rhenium (Re). The Group VIIB metal may act as a promoter to improve the efficiency of the dry reforming activity of the catalyst.

[0040] In some embodiments, the catalyst comprises from about 0.5 weight percent (wt.%) to about 15 wt.% Ni. In some embodiments, the catalyst comprises from about 0.5 wt.% to about 10 wt.% Ce2O3. In some embodiments, the catalyst comprises from about 0.5 wt.% to about 5 wt.% La2O3. In some embodiments, the catalyst comprises from about 0.1 wt.% to about 2 wt.% Pt. In some embodiments, the catalyst comprises up to about 1 wt.% ZrO2. In some embodiments, the catalyst comprises up to about 2 wt.% Rh. In some embodiments, the catalyst comprises up to about 2 wt.% Re.

[0041] In some embodiments, the catalyst is supported on an aluminate support. In such embodiments, the aluminate support can be considered as part of the catalyst. The aluminate support can include magnesium aluminate, calcium aluminate, or a mixture of the two. In some embodiments, an alkali metal such as potassium (K) is incorporated into the aluminate support. The inclusion of an alkali metal in the aluminate support can slow down coke formation on the catalyst and thus can slow down catalyst deactivation. In embodiments where the catalyst is supported on an aluminate support doped with K, the catalyst can include about 0.5 wt.% to about 5.0 wt.% K.

[0042] In some embodiments, the catalyst includes a refractory support including alumina (e.g., θ-alumina), magnesium aluminate, or a mixture of the two. In some embodiments, a calcium aluminate-based refractory cement is incorporated into the catalyst to improve the mechanical strength of the catalyst. In some embodiments, the catalyst has a carbon content of from about 15 square meters per gram (m 2 / g) to about 125m 2 / g specific surface area.

[0043] The refractory support may be provided in different shapes, such as spheres, extrudates or rings. For the production of hydrogen-rich gas for fuel cells, it may be beneficial to use a refractory support in the form of a sphere, for example having a diameter in the range from about 1 mm to about 4 mm; a complex extrudate, such as a trilobal, quadrilobal or Raschig ring; or a honeycomb structure. For large-scale production of hydrogen-rich gas (e.g., greater than 100,000 standard cubic meters per day), it may be beneficial to use a refractory support in the form of a ring having multiple pores.

[0044] In some embodiments, the catalyst is prepared by a multi-step sequence of impregnation, calcination and reduction of the components on the support. Catalyst impregnation can be carried out using an aqueous solution of a soluble salt (such as a nitrate). In some embodiments, rhodium and rhenium metal salts are impregnated, after which they are decomposed in subsequent heat treatments to form corresponding oxides. After impregnation, the composite material is dried (calcined) at a slow heating rate of, for example, about 0.5°C per minute, until about 120°C is reached, and then the temperature is maintained at about 120°C for about one hour. Then, at a slow heating rate of, for example, about 0.5°C per minute, the temperature is raised to about 250°C, and then the temperature is maintained at about 250°C for about 1.5 hours. The above-mentioned heating (calcination) step can be carried out in the presence of air or another oxygen-containing gas. In some embodiments, after impregnation and before heating, the catalyst can be treated with an ammonia-containing gas at about 60°C for about 10 to about 30 minutes. The catalyst can then be reduced with a hydrogen-containing gas for about 2 hours at a temperature ranging from about 400°C to about 450°C. The above impregnation, calcination and reduction steps may be repeated with salts of Pt and Zr. The above impregnation, calcination and reduction steps may be repeated with salts of Ni, Ce and La. The reduction step of the salts of Ni, Ce and La may be performed at a temperature ranging from about 400°C to about 1,100°C, from about 600°C to about 800°C, or from about 700°C to about 750°C.

[0045] In some embodiments, the catalyst is prepared by a single-step sequence of impregnation, calcination, and reduction at a temperature ranging from about 400°C to about 1,100°C, from about 600°C to about 800°C, or from about 700°C to about 750°C. The refractory support can be impregnated with an aqueous solution of a soluble salt such as a nitrate of Ni, Ce, La, and Pt. After impregnation, the composite material is dried (calcined) at a slow heating rate of, for example, about 0.5°C per minute until it reaches about 120°C, and then the temperature is maintained at about 120°C for about one hour. The temperature is then raised to about 250°C at a slow heating rate of, for example, about 0.5°C per minute, and then the temperature is maintained at about 250°C for about 1.5 hours. The temperature is then raised to about 400°C to about 450°C. The above-mentioned heating (calcination) step can be carried out in the presence of air or another oxygen-containing gas. The catalyst may then be reduced with a hydrogen-containing gas at a temperature ranging from about 400° C. to about 1,100° C., from about 600° C. to about 800° C., or from about 700° C. to about 750° C. In some embodiments, the impregnation, drying, and calcination may be repeated one or more times to obtain the desired content of each component in the catalyst, depending on the pore volume in the support.

[0046] In some embodiments, the feed stream 101 also includes water (H2O) in the form of steam. In some embodiments, the feed stream 101 has a ratio of water to carbon (i.e., carbon atoms from any carbon-containing material, such as carbon dioxide and hydrocarbon fuels) in a range from about 1:10 to about 3:1. In some embodiments, the feed stream 101 has a ratio of water to carbon in a range from about 1:10 to about 1:1. Including steam in the feed stream 101 can reduce the severity of the carbon-carbon reaction under the operating conditions of the dry reforming reaction in the reactor 105. Including steam in the feed stream 101 can slow down the formation of coke on the catalyst, and thus can slow down the deactivation of the catalyst. Including steam in the feed stream 101 can increase the ratio of hydrogen to carbon monoxide in the synthesis gas 106 produced by the reactor 105. Including steam in the feed stream 101 can improve the selectivity of the catalyst in producing synthesis gas 106 compared to other carbon-containing compounds.

[0047] Figure 1B An embodiment of the system 100 is shown, which is substantially similar to Figure 1A In some embodiments, the system 100 is Figure 1BAs shown, the system 100 includes an additional hydrogen stream 107 that can be mixed with the syngas 106 exiting the reactor 105. The additional hydrogen stream 107 can be derived, for example, from water electrolysis using renewable energy, thereby allowing chemicals / fuels produced from the syngas 106 to have a reduced carbon footprint. Adding hydrogen to the syngas 106 can increase the ratio of hydrogen to carbon monoxide to comply with downstream processes. For example, some processes that may benefit from increasing the ratio of hydrogen to carbon monoxide in the syngas 106 include methanol production, ethanol production, and acetic acid production.

[0048] Figure 2 2 is a flow chart of an example dry reforming method 200 for producing synthesis gas from hydrocarbon fuels. System 100 can implement dry reforming method 200. In step 202, a feed stream (such as feed stream 101) including a hydrocarbon fuel and carbon dioxide is preheated. For example, in step 202, preheater 103 preheats feed stream 101. In some embodiments, in step 202, feed stream 101 is preheated to a temperature ranging from about 750°C to about 950°C. As previously described, feed stream 101 may also include water in the form of steam. In some embodiments, dry reforming method 200 includes mixing a hydrocarbon fuel (e.g., methane) with carbon dioxide to form feed stream 101 before step 202. In some embodiments, dry reforming method 200 includes mixing a hydrocarbon fuel (e.g., methane) with carbon dioxide and water to form feed stream 101 before step 202.

[0049] In step 204, a preheated feed stream (such as preheated feed stream 104) is flowed to a reactor (such as reactor 105) including a catalyst. The catalyst can be a catalyst described previously. In step 204, the preheated feed stream 104 is flowed to reactor 105 so that the preheated feed stream 104 is contacted with the catalyst. In the absence of oxygen, the catalyst causes a dry reforming reaction (e.g., a reaction represented by equation (1)) in reactor 105 for a period of time sufficient to reform the hydrocarbon fuel to produce synthesis gas (such as synthesis gas 106). In some embodiments, in step 204, the feed stream is heated at a rate of about 1,000 h / min in the absence of oxygen. -1 To about 3,000h -1 In some embodiments, in step 204, during the dry reforming reaction, the operating pressure in the reactor is in the range from about 7 bar to about 28 bar.

[0050] Syngas 106 may be exhausted from reactor 105. In some embodiments, additional hydrogen may be mixed with syngas 106 exhausted from reactor 105 to increase the ratio of hydrogen to carbon monoxide. For example, hydrogen stream 107 may be mixed with syngas 106.

[0051] Examples

[0052] Figure 3A-1 , 3A-2 and 3A-3 provide various graphs showing the thermodynamic equilibrium product compositions of the dry reforming process at various operating pressures and over a range of operating temperatures. Figure 3A-1 , 3A-2 and 3A-3 demonstrate that the selectivity to synthesis gas (hydrogen and carbon monoxide) generally increases with increasing operating temperature. Figure 3A-4 is a graph showing the effect of operating pressure on carbon yield (coking) of a reforming process. Figure 3A-4 It was demonstrated that coke formation generally increases with increasing operating pressure and generally decreases with increasing operating temperature. Figure 3A-1 , 3A-2 In all examples shown in 3A-3 and 3A-4, the CH4:CO2 ratio in the feed stream is 1:1.

[0053] Figure 3B-1 , 3B-2 and 3B-3 provide various graphs showing the effect of operating pressure (7 bar, 14 bar and 28 bar, respectively) on hydrocarbon conversion, product yield and feed / product composition of a dry reforming process at an operating temperature of 700°C. Figure 3B-1 , 3B-2 The horizontal dashed lines in 3B-3 and 3B-3 represent the expected conversion, product yield, and product composition, respectively. Figure 3B-1 , 3B-2 The data points connected in 3B-3 demonstrate the catalyst performance at 700°C and various operating pressures with a feed stream comprising a 1:1 CH4:CO2 ratio.

[0054] Figure 3C-1 , 3C-2 and 3C-3 provide various graphs showing the effect of operating pressure (7 bar, 14 bar and 28 bar, respectively) on hydrocarbon conversion, product yield and feed / product composition of the dry reforming process at an operating temperature of 750°C. Figure 3C-1 , 3C-2 The horizontal dashed lines in 3C-3 and 3C-3 represent the expected conversion, product yield, and product composition, respectively. Figure 3C-1 , 3C-2 The data points connected in 3C-3 demonstrate the catalyst performance at 750°C and various operating pressures with a feed stream comprising a 1:1 CH4:CO2 ratio.

[0055] Figure 3D-1 , 3D-2and 3D-3 provide various graphs showing the effect of operating pressure (7 bar, 14 bar and 28 bar, respectively) on hydrocarbon conversion, product yield and feed / product composition of the dry reforming process at an operating temperature of 800°C. Figure 3D-1 , 3D-2 The horizontal dashed lines in 3D-3 and 3D-3 represent the expected conversion, product yield, and product composition, respectively. Figure 3D-1 , 3D-2 The data points connected in 3D-3 demonstrate the catalyst performance at 800°C and various operating pressures with a feed stream comprising a 1:1 CH4:CO2 ratio.

[0056] The results are shown in Figure 3B-1 , 3B-2 , 3B-3, 3C-1, 3C-2, 3C-3, 3D-1, 3D-2, and 3D-3 for each experimental run: The gas hourly space velocity is 1,500 h -1 ; the molar composition ratio of CH4:CO2:N2:He in the feed stream was 31:31:30:8; the catalyst was pretreated to 700°C for 3 hours; and the total reaction time was 24 hours. These experimental runs demonstrated the effective performance of the catalyst at high temperatures (e.g., 800°C or higher) at operating pressures ranging from about 10 bar to about 15 bar.

[0057] Figure 3E-1 , 3E-2 and 3E-3 provide various graphs showing the gas hourly space velocity (2,000 h -1 and 2,500h -1 ) respectively on the hydrocarbon conversion, product yield and feed / product composition of the dry reforming process. The results are shown in Figure 3E-1 , 3E-2 Each experimental run in the graphs of 3E-3 and 3E-3 was: the molar composition ratio of CH4:CO2:N2:He in the feed stream was 31:31:30:8; the catalyst was pretreated to 800°C for 6 hours; and the total reaction time was 24 hours. Greater gas hourly space velocities tend to have less single-pass conversion and typically mean more cycles occur in the process. Figure 3E-1 , 3E-2 and 3E-3 demonstrated that at an operating temperature of 800 °C and an operating pressure of 28 bar, the catalyst exhibited stable performance when reaching an equilibrium composition within the gas hourly space velocity range.

[0058] Figure 3F-1 , 3F-2and 3F-3 provide various graphs showing the effects of operating temperature (750°C and 800°C) on hydrocarbon conversion, product yield and feed / product composition of a dry reforming process at an operating pressure of 14 bar when the feed stream includes water (CH4:CO2:H2O≈2:2:1). The results are shown in Figure 3F-1 , 3F-2 For each experimental run in the graphs of 3F-3 and 3F-3: the molar composition ratio of CH4:CO2:H2O:N2:He in the feed stream was 26:26:16:26:6; the catalyst was pretreated to 800°C for 6 hours; and the total reaction time was 24 hours. Figure 3F-1 , 3F-2 and 3F-3 demonstrate the effect of adding steam to the feed stream. Under milder operating conditions (e.g., at lower temperatures), the addition of steam can increase the H2:CO ratio in the product, which can improve the useful life of the catalyst. In addition, increasing the H2:CO ratio in the product may benefit various downstream processes (mentioned previously).

[0059] Figure 3G-1 , 3G-2 and 3G-3 provide various graphs showing the effects of operating temperature (750°C and 800°C) on hydrocarbon conversion, product yield and feed / product composition of a dry reforming process at an operating pressure of 14 bar when the feed stream has a reduced CH4:CO2 ratio (1:3). The results are shown in Figure 3G-1 , 3G-2 For each experimental run in the graphs of 3G-3 and 3G-3: the molar composition ratio of CH4:CO2:N2:He in the feed stream was 16:48:32:4; the catalyst was pretreated to 800°C for 6 hours; and the total reaction time was 24 hours. Figure 3G-1 , 3G-2 and 3G-3 demonstrate the effect of adjusting the CH4:CO2 ratio in the feed stream under dry operating conditions (no steam addition) at various operating temperatures. The stability of these results can demonstrate favorable conditions for mitigating coking. As the CO2 content in the feed stream increases, the coke deposits formed during the reaction can potentially react further with the CO2 to form additional CO (e.g., via a reverse Baudrol reaction). Reducing the CH4:CO2 ratio in the feed stream can result in a decrease in the H2:CO ratio in the product syngas, but the H2:CO ratio in the syngas can be adjusted (see, e.g., Figure 1B ).

[0060] Although some of the above examples include an inert gas (e.g., nitrogen (N2), helium (HE), or both) in the feed stream, the inert gas is included to verify the quality of the experiment through mass balance checks, and the inert gas is not necessarily included in industrial applications of the dry reforming methods described herein.

[0061] Although this specification contains many specific implementation details, these should not be interpreted as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to a particular implementation. Certain features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. In contrast, different features described in the context of a single implementation may also be implemented in multiple implementations individually or in any suitable sub-combination. In addition, although previously described features may be described as working in certain combinations and even initially claimed as such, in some cases, one or more features from the claimed combination may be removed from the combination, and the claimed combination may involve sub-combinations or variations of sub-combinations.

[0062] As used in this disclosure, the terms "a", "an" or "the" are used to include one or more than one, unless the context clearly indicates otherwise. The term "or" is used to refer to a non-exclusive "or", unless the context clearly indicates otherwise. The expression "at least one of A and B" has the same meaning as "A, B, or A and B". In addition, it should be understood that the phrases or terms used in this disclosure are used for descriptive purposes only and are not limiting unless otherwise defined. The use of any section headings is intended to assist in reading the document and should not be construed as limiting; information related to the section heading may appear within or outside that particular section.

[0063] As used in this disclosure, the terms "about" or "approximately" can allow for a certain degree of variation in value or range (eg, within 10%, within 5%, or within 1%) of a stated value or a stated range limit.

[0064] As used in this disclosure, the term "substantially" refers to a majority or majority, such as at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more.

[0065] Values ​​expressed in range format should be interpreted in a flexible manner to include not only the values ​​explicitly stated as range limits, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, the range "0.1% to about 5%" or "0.1% to 5%" should be interpreted to include about 0.1% to about 5% and individual values ​​(e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. Unless otherwise indicated, the expression "X to Y" has the same meaning as "about X to about Y". Similarly, unless otherwise indicated, the expression "X, Y, or Z" has the same meaning as "about X, about Y, or about Z".

[0066] Specific embodiments of the subject matter have been described. Other embodiments, modifications, and arrangements of the described embodiments are within the scope of the appended claims and will be apparent to those skilled in the art. Although operations are depicted in a particular order in the drawings or claims, this should not be construed as requiring that such operations be performed in the particular order shown or in an ordered order, or that all of the illustrated operations (some operations may be considered optional) be performed to achieve the desired results. In certain circumstances, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and is performed where deemed appropriate.

[0067] Furthermore, the separation or integration of various system modules and components in the previously described embodiments should not be understood as requiring such separation or integration in all embodiments, but rather it should be understood that the described components and systems may generally be integrated together or packaged into multiple products.

[0068] Therefore, the previously described example embodiments do not define or limit the present disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of the present disclosure.

Claims

1. A dry reforming process for producing synthesis gas from hydrocarbon fuels, comprising: preheating a feed stream comprising methane and carbon dioxide, wherein the molar ratio of methane to carbon dioxide in the feed stream is 1:3; as well as The feed stream is flowed to a reactor containing a catalyst, so that the feed stream contacts the catalyst in the absence of oxygen and water vapor and causes a dry reforming reaction in the reactor for a period of time sufficient to reform the methane to produce the synthesis gas, the catalyst comprising nickel (Ni), lanthanum oxide (La2O3), cerium oxide (Ce2O3), platinum (Pt), zirconium oxide (ZrO2), rhodium (Rh) and rhenium (Re), the catalyst being supported on an aluminate support bonded with potassium (K), the aluminate support being in the form of a porous ring, wherein the dry reforming reaction is carried out in the absence of a combustion reaction in the reactor, wherein the ... in the absence of oxygen and water vapor at a rate of from 1,000 h -1 Up to 3,000h -1 The catalyst is contacted with a gas hourly space velocity in the range of 1 to 20 bar and the operating pressure is in the range of 7 bar to 28 bar.

2. The dry reforming method according to claim 1, wherein: The feed stream is preheated to a temperature ranging from 750 degrees Celsius (°C) to 950°C.

3. The dry reforming method according to claim 1, wherein: The catalyst comprises: 0.5 weight percent (wt.%) to 15 wt.% Ni; 0.5 wt.% to 10 wt.% Ce2O3; 0.5 wt.% to 5 wt.% La2O3; 0.1 wt.% to 2 wt.% Pt; Up to 1 wt.% ZrO2; Up to 2 wt.% Rh; as well as Up to 2 wt.% Re.

4. The dry reforming method according to claim 3, wherein: The catalyst contains K in an amount of 0.5 wt. % to 5.0 wt. %.

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