Dry reforming of hydrocarbons

Abstract

A dry reforming process 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 passed through a reactor. The reactor includes a catalyst. Passing the feed stream through the reactor contacts the feed stream with the catalyst in the absence of oxygen and causes a dry reforming reaction within the reactor for a time sufficient to reform the hydrocarbon fuel and produce synthesis gas. The catalyst includes nickel (Ni), lanthanum oxide (La2O3), cerium oxide (Ce2O3), and platinum (Pt).

Description

[Technical Field]

[0001] The present disclosure relates to hydrocarbon reforming, and in particular to dry reforming of hydrocarbons. Priority claims CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 16 / 927,642, filed July 13, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Synthesis gas, also known as syngas, is a fuel gas mixture containing hydrogen, carbon monoxide, and sometimes carbon dioxide. Syngas is combustible and can be utilized as a fuel in internal combustion engines. In some cases, syngas can be used as an intermediate for producing synthetic petroleum for use as a fuel or lubricant. Syngas can also be used to produce methanol or as a hydrogen source for various processes. Hydrocarbon reforming is an example of a process for producing synthesis gas. Summary of the Invention

[0003] This disclosure describes techniques related to hydrocarbon reforming.

[0004] Certain embodiments of the present subject matter can be implemented as a dry reforming process for producing synthesis gas from a hydrocarbon fuel. A feed stream is preheated. The feed stream includes a hydrocarbon fuel and carbon dioxide. The feed stream is flowed into a reactor. The reactor includes a catalyst. Flowing the feed stream into the reactor contacts the feed stream with the catalyst in the absence of oxygen and causes a dry reforming reaction within 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).

[0005] This and other aspects can include one or more of the following features.

[0006] In some embodiments, the feed stream is preheated to a temperature in the range of from about 750 degrees Celsius (°C) to about 950°C.

[0007] In some embodiments, the operating pressure in the reactor during the dry reforming reaction ranges from about 7 bar to about 28 bar.

[0008] In some embodiments, the feed stream has a carbon dioxide to hydrocarbon ratio ranging from about 1:1 to about 4:1.

[0009] In some embodiments, the carbon dioxide to hydrocarbon ratio of the feed stream ranges from about 1:1 to about 2:1.

[0010] In some embodiments, the feed stream comprises water.

[0011] In some embodiments, the feed stream has a water to carbon ratio ranging from about 1:10 to about 3:1.

[0012] In some embodiments, the water to carbon ratio of the feed stream ranges from about 1:10 to about 1:1.

[0013] In some embodiments, the catalyst comprises zirconium oxide (ZrO 2 ), rhodium (Rh), rhenium (Re), and an aluminate support.

[0014] Some embodiments include about 0.5 weight percent (wt%) to about 15 wt% Ni, about 0.5 wt% to about 10 wt% CeO, about 0.5 wt% to about 5 wt% LaO, about 0.1 wt% to about 2 wt% Pt, up to about 1 wt% ZrO, up to about 2 wt% Rh, and up to about 2 wt% Re.

[0015] In some embodiments, potassium (K) is incorporated into the aluminate support.

[0016] In some embodiments, the catalyst comprises about 0.5% to about 5.0% K by weight.

[0017] The details of one or more implementations of the subject matter of this disclosure are set forth in the accompanying drawings and specification. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0018] [Figure 1A] FIG. 1A is a schematic diagram of an exemplary system for dry reforming of hydrocarbons. [Figure 1B] FIG. 1B is a schematic diagram of an exemplary system for dry reforming of hydrocarbons. [Figure 2] FIG. 2 is a flow chart of an exemplary process for dry reforming of hydrocarbons. [Figure 3A] FIG. 3A is a plot showing the thermodynamic equilibrium product composition of the dry reforming process in parts 3A-1, 3A-2, 3A-3, and 3A-4. [Figure 3B] FIG. 3B is a plot showing the effect of operating pressure on the dry reforming process in parts 3B-1, 3B-2, and 3B-3. [Figure 3C] FIG. 3C is a plot showing the effect of operating pressure on the dry reforming process in parts 3C-1, 3C-2, and 3C-3. [Figure 3D] FIG. 3D is a plot illustrating the effect of operating pressure on the dry reforming process in parts 3D-1, 3D-2, and 3D-3. [Figure 3E] FIG. 3E, parts 3E-1, 3E-2, and 3E-3, are plots illustrating the effect of gas hourly space velocity (GHSV) on the dry reforming process. [Figure 3F] FIG. 3F, parts 3F-1, 3F-2, and 3F-3, are plots illustrating the effect of operating temperature on the dry reforming process. [Figure 3G] FIG. 3G is a plot illustrating the effect of operating temperature on the dry reforming process in parts 3G-1, 3G-2, and 3G-3. DETAILED DESCRIPTION OF THE INVENTION

[0019] This disclosure describes hydrocarbon reforming. The conversion of hydrocarbon fuels to hydrogen can be carried out by several processes, including hydrocarbon steam reforming, partial oxidation reforming, autothermal reforming, and dry reforming. Hydrocarbon dry reforming involves the reaction of carbon dioxide (CO) with a fuel (e.g., methane, CH) in the presence of a catalyst and in the absence of oxygen to produce hydrogen (H) and carbon monoxide (CO), as shown in equation (1). The mixture of hydrogen and carbon monoxide can be referred to as synthesis gas (syngas). In some cases, synthesis gas also contains carbon dioxide. [ka]

[0020] The subject matter described in this disclosure can be implemented in certain embodiments to achieve one or more of the following advantages: Dry reforming produces hydrogen and carbon monoxide in a 1:1 molar ratio, which is suitable for a diverse array of hydroformylation applications; approximately half of the carbon atoms in the synthesis gas obtained from the dry reforming process come from carbon dioxide instead of methane; this reduces the dry reforming process's dependency on methane feedstock compared to other reforming processes (e.g., steam reforming, in which all carbon atoms come from methane); furthermore, carbon dioxide is a known greenhouse gas and is a feedstock for the dry reforming process that forms useful products, e.g., instead of being emitted into the atmosphere; the catalysts described herein exhibit resistance to coke formation and sintering, even under conditions of high temperature and pressure; the described processes and catalysts enable an economical way to reduce greenhouse gas emissions; the described processes can integrate renewable hydrogen in existing industrial processes, mitigating the carbon footprint of chemicals and fuels.

[0021] While dry reforming is known, currently known catalysts, such as nickel-alumina-based catalysts, can suffer from deactivation due to excessive coke deposition and agglomeration (i.e., sintering) of metal particles at the high temperatures required for dry reforming, which can reduce the catalyst's usable surface area. Sintering involves the agglomeration of small metal particles to form larger metal particles, resulting in a reduction in the catalyst's active sites. Coking involves the cracking (decomposition) of carbon-containing compounds on the catalyst surface, which imparts selectivity to undesirable side reaction products and also reduces the catalyst's active sites. Group VIII noble metal-based catalysts may exhibit lower susceptibility to coking compared to nickel-based catalysts, but they may also be more expensive to form and more susceptible 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 due to coking and sintering.

[0022] Referring to FIG. 1A, system 100 includes feed stream 101, preheater 103, and reactor 105. 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 vaporized liquid hydrocarbons. In some implementations, feed stream 101 has a carbon dioxide to hydrocarbon ratio in the range of about 1:1 to about 4:1. In some implementations, feed stream 101 has a carbon dioxide to hydrocarbon ratio in the range of about 1:1 to about 2:1. For example, feed stream 101 has a carbon dioxide to methane ratio in the range of about 1:1 to about 4:1 or about 1:1 to about 2:1. Feed stream 101 is free of gas (O2).

[0023] Feed stream 101 flows to preheater 103. Preheater 103 is configured to preheat feed stream 101. In some embodiments, preheater 103 is configured to preheat feed stream 101 to a temperature in a range of about 700 degrees Celsius (°C) to about 950°C. In some embodiments, preheater 103 is configured to preheat feed stream 101 to a temperature in a range of about 700°C to about 850°C. In some embodiments, preheater 103 is configured to preheat feed stream 101 to a temperature in a range of about 750°C to about 950°C. Referring to equation (1), the dry reforming reaction is endothermic. In some embodiments, preheating feed stream 101 to a temperature above 750°C can improve selectivity for the production of hydrogen and carbon monoxide (which are preferred products) and avoid the formation of other carbon-containing compounds. Preheating the feed stream 101 (e.g., to a temperature above 750°C or above 800°C) can mitigate methane decomposition both during the preheating process and in the dry operating mode of the dry reforming process (i.e., without the addition of steam).

[0024] The preheated feed stream 104 exits 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. In the reactor, methane reacts with carbon dioxide to produce synthesis gas 106 (carbon monoxide and hydrogen). In other words, in the reactor 105, the dry reforming reaction represented by equation (1) occurs:

[0025] The reactor 105 contains a catalyst. The preheated feed stream 104 is flowed into the reactor 105, where it contacts the catalyst. In the absence of oxygen, the catalyst accelerates and causes a dry reforming reaction to occur within the reactor for a period of time sufficient to reform the hydrocarbon fuel (e.g., methane) and produce synthesis gas 106. Because oxygen gas is not introduced into the reactor 105, combustion does not occur within the reactor 105. In some embodiments, the operating pressure within the reactor 105 during the dry reforming reaction ranges from about 7 bar to about 28 bar. On the one hand, because the dry reforming reaction forms a volume of product that is greater than the volume of reactants, a lower operating pressure within the reactor 105 may be preferred during the dry reforming reaction in some cases. On the other hand, a higher operating pressure allows for an increased throughput of reactants processed within the reactor 105; therefore, a higher operating pressure within the reactor 105 may be preferred during the dry reforming reaction in some cases. In some embodiments, the operating pressure in reactor 105 depends on the operating pressure of the downstream operation (e.g., syngas application or purification). For example, in applications using syngas to produce dimethyl ether (DME), the operating pressure of such applications tends to be higher; therefore, the syngas produced from reactor 105 can be compressed, and the operating pressure in reactor 105 can be optimized for improved conversion at pressures above 10 bar. In some embodiments, coking becomes more dominant at higher pressures, especially when the dry reforming reaction is completely dry (i.e., no water is added in the formation of steam), so under such conditions, the operating pressure in reactor 105 during the dry reforming reaction ranges from about 10 bar to about 15 bar. The operating pressure range can be expanded by adding water in the formation of steam with the feed to reactor 105. The operating pressure in reactor 105 during the dry reforming reaction can be determined based on one or more of the factors mentioned above and the economics of the process.

[0026] In some embodiments, the catalyst in reactor 105 is pretreated. For example, the catalyst is preheated in reactor 105 so that the catalyst is at a desired temperature before feed stream 104 flows into reactor 105. In some embodiments, the interior volume of reactor 105 is preheated so that the operating temperature in reactor 105 is at a desired temperature before feed stream 104 flows into reactor 105. In some embodiments, the desired temperature of the catalyst, the operating temperature in reactor 105, or both, is the same as, or within a 10% deviation from, the temperature to which feed stream 104 is preheated in preheater 103.

[0027] The catalyst comprises a rare earth metal oxide, such as lanthanum oxide (La2O3), cerium oxide (Ce2O3), or a mixture of both. In some embodiments, the catalyst comprises a Group 4 metal oxide, such as zirconium oxide (ZrO2). In some embodiments, the catalyst comprises nickel (Ni), a reducible compound of Ni (e.g., nickel oxide (NiO)), or a mixture of both. In some embodiments, the catalyst comprises a platinum group metal, such as platinum (Pt), Rh, or a mixture of both. The platinum group metal may be included in pure elemental form or as part of a compound containing a platinum group metal. In some embodiments, the catalyst comprises a Group VIIB metal, such as rhenium (Re). The Group VIIB metal can function as a promoter to enhance the efficiency of the dry reforming activity of the catalyst.

[0028] In some embodiments, the catalyst comprises about 0.5 weight percent (wt%) to about 15 wt% Ni. In some embodiments, the catalyst comprises about 0.5 wt% to about 10 wt% Ce2O3. In some embodiments, the catalyst comprises about 0.5 wt% to about 5 wt% La2O3. In some embodiments, the catalyst comprises 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.

[0029] In some embodiments, the catalyst is supported on an aluminate support. In such embodiments, the aluminate support can be considered part of the catalyst. The aluminate support can include magnesium aluminate, calcium aluminate, or a mixture of both. 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 mitigate coke formation on the catalyst and, therefore, catalyst deactivation. In embodiments where the catalyst is supported on an aluminate support with incorporated K, the catalyst can include about 0.5 wt % to about 5.0 wt % K.

[0030] In some embodiments, the catalyst comprises a refractory support comprising alumina (e.g., theta-alumina), magnesium aluminate, or a mixture of both. 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 surface area of ​​about 15 square meters per gram (m 2 / g) to approximately 125 m 2 / g.

[0031] The refractory support can be provided in different shapes, such as spheres, extrudates, or rings. For the production of hydrogen-rich gas for use in fuel cells, it is advantageous to use a refractory support in the form of a sphere, for example, having a diameter in the range of about 1 millimeter to about 4 millimeters; a complex extrudate, for example, a trilobe, a quadralobe, or a Raschig ring; or a honeycomb structure. For large-scale production of hydrogen-rich gas (for example, more than 100,000 normal cubic meters per day), it may be advantageous to use a refractory support in the form of a ring with many holes.

[0032] 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 salt. In some embodiments, rhodium and rhenium metal salts are impregnated, after which they decompose to form the corresponding oxides during subsequent heat treatment. After impregnation, the composite material is dried (calcined) at a slow heating rate, e.g., about 0.5°C per minute, until it reaches about 120°C, and the temperature is then maintained at about 120°C for about 1 hour. The temperature is then increased to about 250°C at a slow heating rate, e.g., about 0.5°C per minute, and the temperature is then maintained at about 250°C for about 1.5 hours. The above heating (calcination) step can be carried out in the presence of air or another oxygen-containing gas. In some embodiments, after impregnation but 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 at a temperature ranging from about 400°C to about 450°C for about 2 hours. The aforementioned impregnation, calcination, and reduction steps can be repeated with Pt and Zr salts. The aforementioned impregnation, calcination, and reduction steps can be repeated with Ni, Ce, and La salts. The reduction step of the Ni, Ce, and La salts can be carried out at a temperature ranging from about 400°C to about 1100°C, from about 600°C to about 800°C, or from about 700°C to about 750°C.

[0033] In some embodiments, the catalyst is prepared by a single-step sequence of impregnation, calcination, and reduction at temperatures ranging from about 400°C to about 1100°C, about 600°C to about 800°C, or about 700°C to about 750°C. The refractory support can be impregnated with an aqueous solution of soluble salts, such as nitrates of Ni, Ce, La, and Pt. After impregnation, the composite is dried (calcined) at a slow heating rate, e.g., about 0.5°C per minute, until it reaches about 120°C, and the temperature is then maintained at about 120°C for about 1 hour. The temperature is then increased to about 250°C at a slow heating rate, e.g., about 0.5°C per minute, and the temperature is then maintained at about 250°C for about 1.5 hours. The temperature is then increased to about 400°C to about 450°C. The heating (calcining) step described above can be carried out in the presence of air or another oxygen-containing gas. The catalyst can then be reduced with a hydrogen-containing gas at a temperature ranging from about 400° C. to about 1100° C., from about 600° C. to about 800° C., or from about 700° C. to about 750° C. In some embodiments, depending on the pore volume in the support, the impregnation, drying, and calcination can be repeated one or more times to obtain the desired content of each component in the catalyst.

[0034] In some embodiments, feed stream 101 also includes water (HO) in the form of steam. In some embodiments, feed stream 101 has a water to carbon (i.e., carbon atoms from any carbon-containing species, such as carbon dioxide and hydrocarbon fuels) ratio ranging from about 1:10 to about 3:1. In some embodiments, feed stream 101 has a water to carbon ratio ranging from about 1:10 to about 1:1. The inclusion of steam in feed stream 101 can reduce the severity of carbon-carbon reactions at the operating conditions of the dry reforming reaction in reactor 105. The inclusion of steam in feed stream 101 can reduce coke formation on the catalyst, and therefore, catalyst deactivation. The inclusion of steam in feed stream 101 can increase the ratio of hydrogen to carbon monoxide in the syngas 106 produced by reactor 105. The inclusion of steam in feed stream 101 can improve the selectivity of the catalyst in producing syngas 106 as opposed to other carbon-containing compounds.

[0035] FIG. 1B shows an embodiment of system 100 substantially similar to system 100 shown in FIG. 1A. In some implementations, as shown in FIG. 1B, system 100 includes an additional hydrogen stream 107 that can be mixed with the syngas 106 exiting reactor 105. The additional hydrogen stream 107 can be sourced, for example, from water electrolysis using renewable energy, allowing chemicals / fuels produced from syngas 106 to have a reduced carbon footprint. The addition of hydrogen to syngas 106 can increase the ratio of hydrogen to carbon monoxide to tailor it to downstream processes. For example, some processes that may benefit from an increased ratio of hydrogen to carbon monoxide in syngas 106 include methanol production, ethanol production, and acetic acid production.

[0036] FIG. 2 is a flowchart of an exemplary dry reforming process 200 for producing synthesis gas from a hydrocarbon fuel. System 100 can implement dry reforming process 200. In step 202, a feed stream (such as feed stream 101) comprising a hydrocarbon fuel and carbon dioxide is preheated. For example, preheater 103 preheats feed stream 101 in step 202. In some embodiments, feed stream 101 is preheated to a temperature in the range of about 750° C. to about 950° C. in step 202. As mentioned above, feed stream 101 can also include water in the form of steam. In some embodiments, dry reforming process 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 process 200 includes mixing a hydrocarbon fuel (e.g., methane) with carbon dioxide and water to form feed stream 101 before step 202.

[0037] In step 204, a preheated feed stream (such as preheated feed stream 104) is passed through a reactor (such as reactor 105) containing a catalyst. The catalyst may be any of the catalysts described above. Passing preheated feed stream 104 through reactor 105 in step 204 results in preheated feed stream 104 contacting the catalyst. In the absence of oxygen, the catalyst induces a dry reforming reaction (e.g., the reaction represented by equation (1)) within reactor 105 for a time sufficient to reform the hydrocarbon fuel to produce synthesis gas (such as synthesis gas 106). In some embodiments, the feed stream is passed through a dry reforming reaction (e.g., the reaction represented by equation (1)) within reactor 105 for about 1000 hours in step 204. -1 ~approximately 3000 hours -1 In some embodiments, the operating pressure in the reactor during the dry reforming reaction in step 204 ranges from about 7 bar to about 28 bar.

[0038] Syngas 106 can be discharged from reactor 105. In some embodiments, additional hydrogen can be mixed with the syngas 106 discharged from reactor 105 to increase the ratio of hydrogen to carbon monoxide. For example, hydrogen stream 107 can be mixed with syngas 106.

[0039] example

[0040] Sections 3A-1, 3A-2, and 3A-3 of Figure 3A provide various plots showing the thermodynamic equilibrium product composition of the dry reforming process over a range of operating temperatures at various operating pressures. Sections 3A-1, 3A-2, and 3A-3 of Figure 3A show that syngas (hydrogen and carbon monoxide) selectivity generally increases with increasing operating temperature. Section 3A-4 of Figure 3A is a plot showing the effect of operating pressure on the carbon yield (coking) of the dry reforming process. Section 3A-4 of Figure 3A demonstrates that coke formation generally increases with increasing operating pressure and generally decreases with increasing operating temperature. In all examples shown in the figures, Sections 3A-1, 3A-2, 3A-3, and 3A-4 of Figure 3A, the CH:CO ratio in the feed stream was 1:1.

[0041] Parts 3B-1, 3B-2, and 3B-3 of Figure 3B provide various plots illustrating the effect of operating pressure (7 bar, 14 bar, and 28 bar, respectively) on the hydrocarbon conversion, product yield, and feed / product composition of a dry reforming process at an operating temperature of 700°C. The horizontal dotted lines in the figures represent the expected conversion, product yield, and product composition, respectively, in parts 3B-1, 3B-2, and 3B-3 of Figure 3B. The connected data points in parts 3B-1, 3B-2, and 3B-3 of Figure 3B show the performance of the catalysts using feedstreams containing a 1:1 CH:CO ratio at 700°C and various operating pressures.

[0042] Parts 3C-1, 3C-2, and 3C-3 of Figure 3C provide various plots showing the effect of operating pressure (7 bar, 14 bar, and 28 bar, respectively) on the hydrocarbon conversion, product yield, and feed / product composition of a dry reforming process at an operating temperature of 750°C. The horizontal dotted lines in Parts 3C-1, 3C-2, and 3C-3 of Figure 3C represent the expected conversion, product yield, and product composition, respectively. The connected data points in Parts 3C-1, 3C-2, and 3C-3 of Figure 3C show the catalyst performance using a feed stream containing a 1:1 CH:CO ratio at 750°C and various operating pressures.

[0043] Parts 3D-1, 3D-2, and 3D-3 of Figure 3D provide various plots showing the effect of operating pressure (7 bar, 14 bar, and 28 bar, respectively) on the hydrocarbon conversion, product yield, and feed / product composition of a dry reforming process at an operating temperature of 800°C. The horizontal dashed lines in parts 3D-1, 3D-2, and 3D-3 of Figure 3D represent the expected conversion, product yield, and product composition, respectively. The connected data points in parts 3D-1, 3D-2, and 3D-3 of Figure 3D show the performance of the catalysts using feed streams containing a 1:1 CH:CO ratio at 800°C and various operating pressures.

[0044] For each of the experimental runs whose results are shown in the plots in parts 3B-1, 3B-2, and 3B-3 of Figure 3B, parts 3C-1, 3C-2, and 3C-3 of Figure 3C, and parts 3D-1, 3D-2, and 3D-3 of Figure 3D: Gas hourly space velocity (GHSV) was 1500 h -1 The molar composition ratio of CH:CO:N:He in the feed stream was 31:31:30:8; the catalyst was pretreated at 700 °C for 3 hours; and the total reaction run time was 24 hours. These experimental runs demonstrate 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.

[0045] Parts 3E-1, 3E-2, and 3E-3 of Figure 3E show the hydrocarbon conversion, product yield, and gas hourly space velocity (GHSV) for feed / product components of the dry reforming process at an operating temperature of 800°C and an operating pressure of 28 bar (2000 h). -1Various plots are provided showing the effect of the GHSV (temperature, temperature, and pressure) on the catalyst composition (temperature, temperature, and pressure). For each of the experimental runs shown in the plots in parts 3E-1, 3E-2, and 3E-3 of Figure 3E, the molar composition ratio of CH:CO:N:He in the feed stream was 31:31:30:8; the catalyst was pretreated at 800 °C for 6 hours; and the total reaction run time was 24 hours. Higher gas hourly space velocities (GHSV) tend to have lower single-pass conversions, which typically means more recycle (regeneration) occurs in the process. Parts 3E-1, 3E-2, and 3E-3 of Figure 3E demonstrate that the catalyst exhibits stable performance in reaching equilibrium composition over a range of GHSVs at an operating temperature of 800 °C and an operating pressure of 28 bar.

[0046] Parts 3F-1, 3F-2, and 3F-3 of Figure 3F provide various plots 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 contained moisture (CH:CO:HO approximately equal to 2:2:1). For each of the experimental runs whose results are shown in the plots in Parts 3F-1, 3F-2, and 3F-3 of Figure 3F: the molar component ratios of CH:CO:HO:N:He in the feed stream were 26:26:16:26:6; the catalyst was pretreated to 800°C for 6 hours; and the total reaction run time was 24 hours. Parts 3F-1, 3F-2, and 3F-3 of Figure 3F demonstrate the effect of adding steam to the feed stream. The addition of steam can increase the H:CO ratio in the product under milder operating conditions (e.g., lower temperatures), which can improve the operating life of the catalyst. Furthermore, the increased H:CO ratio in the product can be advantageous for various downstream processes (discussed above).

[0047] Figure 3G, parts 3G-1, 3G-2, and 3G-3, respectively, provide various plots showing the effect of operating temperature (750 °C and 800 °C) on the hydrocarbon conversion, product yield, and feed / product composition of a dry reforming process at an operating pressure of 14 bar when the feed stream had a reduced CH:CO ratio (1:3). For each of the experimental run results shown in the plots in parts 3G-1, 3G-2, and 3G-3 of Figure 3G, the molar component ratios in the feed stream were 16:48:32:4; the catalyst was treated at 800 °C for 6 hours; and the total reaction run time was 24 hours. Figure 3G, parts 3G-1, 3G-2, and 3G-3 show the effect of adjusting the CH:CO ratio in the feed stream under dry operating conditions (no added steam) at various operating temperatures. The stability of these results may demonstrate favorable conditions for mitigating coking. With increasing CO content in the feed stream, coke deposits that form during the reaction can potentially further react with CO to form additional CO (e.g., via the reverse Boudouard reaction). Decreasing the CH:CO ratio in the feed stream decreases the H:CO ratio in the product syngas, but the H:CO ratio in the syngas can be adjusted (e.g., see Figure 1B).

[0048] Although some of the above examples included inert gas (e.g., nitrogen (N), helium (He), or both) in the feed stream, the inert gas was included to verify the quality of the experiment through mass balance checks. Inert gas is not necessarily included in industrial applications of the dry reforming process described herein.

[0049] While this specification contains details of numerous specific embodiments, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be unique to particular embodiments. Certain features described herein in the context of individual embodiments can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although the foregoing features may be described as working in particular combinations, one or more features from a claimed combination, even if originally claimed as such, may in some cases be separated from that combination, and the claimed combination may be directed to subcombinations or variations of the subcombination.

[0050] As used in this disclosure, the terms "a," "an," or "the" are used to include one or more unless the context clearly dictates otherwise. The term "or" is used to refer to a non-exclusive "or" unless otherwise indicated. The phrase "at least one of A and B" has the same meaning as "A, B, or A and B." Additionally, it should be understood that phraseology or terminology used in this disclosure and not otherwise defined is for purposes of description only and not limitation. Any use of section headings is intended to aid in the reading and comprehension of the document and should not be construed as limiting, and information associated with a section heading may occur within or outside that particular section.

[0051] As used in this disclosure, the term "about" or "approximately" can allow for a degree of variation of a value or range, for example, within 10%, within 5%, or within 1% of the stated limits of the stated value or range.

[0052] As used in this disclosure, the term "substantially" refers to a majority or majority of 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.

[0053] Values ​​expressed in range format should be interpreted in an open manner to include not only the numerical values ​​explicitly recited as the limits of the range, but also all individual numerical values ​​or subranges subsumed within that range, as if each numerical value and subrange were explicitly recited. For example, a range of "0.1% to about 5%" or "0.1% to 5%" should be interpreted to include about 0.1% to about 5%, as well as individual values ​​(e.g., 1%, 2%, 3%, and 4%) and subranges within the stated range (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%). The statement "X to Y" has the same meaning as "about X to about Y" unless otherwise specified. Similarly, the statement "X, Y, Z" has the same meaning as "about X, about Y, about Z" unless otherwise indicated.

[0054] Specific embodiments of the present subject matter have been described. Other embodiments, modifications, and permutations of the described embodiments, as will be apparent to those skilled in the art, are within the scope of the following claims. While operations are shown in the drawings or claims in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown, or in any sequential order, or that all of the shown operations be performed (although some operations may be considered optional), to achieve desirable results. In certain situations, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and may be performed as deemed appropriate.

[0055] Furthermore, it should be understood that the separation or integration of various system modules and components in the foregoing embodiments should not be understood as requiring such separation or integration in all embodiments, and that the components and systems described may generally be integrated together or packaged in multiple products.

[0056] Accordingly, the foregoing exemplary 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. 1. A dry reforming process for producing synthesis gas from a hydrocarbon fuel, comprising: preheating the feed stream comprising the hydrocarbon fuel and carbon dioxide; flowing the feed stream through a reactor containing a catalyst, whereby the feed stream contacts the catalyst in the absence of oxygen and a dry reforming reaction occurs within the reactor for a time sufficient to reform the hydrocarbon fuel and produce the synthesis gas, the catalyst comprising nickel (Ni), a rare earth metal oxide, and platinum (Pt), and the rare earth metal oxide comprises lanthanum oxide (La2O3), cerium oxide (Ce2O3), or a mixture of lanthanum oxide (La2O3) and cerium oxide (Ce2O3); A dry reforming process comprising:

2. the feed stream is preheated to a temperature in the range of about 750 degrees Celsius (°C) to about 950°C; The dry reforming process of claim 1.

3. the operating pressure within the reactor during the dry reforming reaction is in the range of about 7 bar to about 28 bar; The dry reforming process of claim 1.

4. the feed stream has a carbon dioxide to hydrocarbon ratio in the range of about 1:1 to about 4:1; The dry reforming process of claim 1.

5. the ratio of carbon dioxide to hydrocarbon in the feed stream is in the range of from about 1:1 to about 2:1; The dry reforming process of claim 4.

6. the feed stream comprises water; The dry reforming process of claim 1.

7. the feed stream has a water to carbon ratio in the range of about 1:10 to about 3:1; The dry reforming process of claim 6.

8. the water to carbon ratio of the feed stream ranges from about 1:10 to about 1:1; The dry reforming process of claim 7.

9. The catalyst is zirconium oxide (ZrO ２ ), rhodium (Rh), rhenium (Re), and an aluminate support; The dry reforming process of claim 1.

10. The catalyst comprises: about 0.5 weight percent (w%) to about 15 w% 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 Re up to about 2 wt. %; Including, The dry reforming process of claim 9.

11. Potassium (K) is incorporated into the aluminate support; The dry reforming process of claim 10.

12. the catalyst comprises about 0.5 wt % to about 5.0 wt % K; The dry reforming process of claim 11.

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