KR20200132345A - Catalyst for synthesizing synthetic natural gas with high heating value and method of synthesizing the synthetic natural gas using the catalyst - Google Patents

Abstract

Disclosed is a catalyst to be used in a reaction for synthesizing a high-heating-value synthetic natural gas, which contains C2-4 paraffinic hydrocarbons, by making carbon monoxide react with hydrogen. The catalyst comprises: an alumina support; and a binary metal catalyst component, which is supported on the alumina support and is composed of cobalt oxide and iron oxide.

Description

A catalyst for producing synthetic natural gas having a high calorific value and a method for synthesizing paraffin-based synthetic natural gas with a high calorific value using the same.

The present invention relates to a catalyst applied to a reaction for synthesizing synthetic natural gas having a high calorific value by reacting carbon monoxide and hydrogen, and a method for synthesizing synthetic natural gas having a high calorific value using the same.

Synthetic natural gas, a potential replacement for fossil fuels, has received a lot of attention and is being produced commercially from other starting materials including coal and biomass. In the synthetic natural gas process, 1 mole of carbon monoxide and 3 moles of hydrogen react as described in Scheme 1 below to produce methane and water.

[Scheme 1]

Since methane emits the smallest amount of carbon dioxide per unit of energy in all fossil fuels, synthetic natural gas is expected to reduce global warming problems. However, the heating value of methane is typically lower than the standard heating value for energy generation. Therefore, in order to increase the calorific value, it is necessary to add liquefied petroleum gas (LPG) such as propane and butane to low-calorie natural gas, but the LPG price has a problem that the oil price is strongly affected. This problem can be overcome by adding synthetic hydrocarbons ranging from C2 to C4 using the Fischer Tropsch reaction. In addition, olefins not only exhibit a low calorific value, but also are easier to liquefy than paraffins of the same carbon chain length under high pressure pipeline conditions, and thus, in order to replace LPG, a high paraffin ratio in the gas product must be maintained. Therefore, in order to replace LPG, the catalyst must produce light hydrocarbons of C2~C4 with a high paraffin ratio.

Because of their high catalytic activity, high methane selectivity and low cost, nickel-based catalysts have been used commercially to produce synthetic natural gas. However, nickel-based catalysts have a problem with higher selectivity toward methane than hydrocarbons having 2 or more carbon atoms. There are several methods of producing light hydrocarbons of C2 to C4 from a synthesis gas composed of carbon monoxide and hydrogen, for example, direct LPG synthesis, isosynthesis, and light olefin synthesis. These three methods are carried out at low H2/CO ratios of 0.5 to 2 to suppress the production of methane. The LPG synthesis method provides propane and butane, while the iso synthesis method has high selectivity toward isobutane or isobutene. The direct LPG synthesis method and the iso synthesis method show relatively low carbon monoxide conversion (CO conversion) and high carbon dioxide selectivity. The light olefin synthesis reaction is a Fischer Tropsch for producing variable hydrocarbons of C2 to C4 at a high temperature of 300 to 400°C, which is higher than 220 to 250°C, which is the temperature applied in the traditional Fischer Tropsch reaction for hydrocarbons with 5 or more carbon atoms. It's part of the reaction. Nevertheless, despite the high C3~C4 selectivity, due to the high olefin ratio, there is a problem that the Fischer Tropsch reaction for olefin synthesis is not suitable.

Inui et al. Reported a 'Co-Mn-Ru / Al 2 O 3' catalyst for the high-calorie gas as compared with synthesis gas having a C2 ~ C4 hydrocarbons added via a high-calorie methanation process. 'Co-Mn-Ru / Al 2 O 3' catalyst exhibited a selectivity of C2 ~ C4 and higher carbon monoxide conversion rate of 19.1% of 98.8%. However, the calorific value obtained was still not sufficient to replace LPG-added natural gas. Lee et al. Is on the 'Co-Mn-Ru / Al 2 O 3' catalyst was investigated the role of each component, but offer the optimum composition of the 'Co-Mn-Ru / Al 2 O 3' catalyst, still synthetic natural gas There are insufficient parts to improve the calorific value of.

Recently, several attempts have been made to improve the calorific value of synthetic natural gas, but the catalyst under various process conditions has not been investigated in detail, although the catalyst behavior is affected by the catalyst type and process conditions.

One object of the present invention is a synthetic natural gas having a high calorific value by containing a two-component metal catalyst component consisting of cobalt oxide and iron oxide, exhibiting a high CO conversion rate, and containing a high proportion of C2 to C4 paraffinic hydrocarbons It is to provide a catalyst for producing synthetic natural gas that can synthesize.

Another object of the present invention is to provide a method for synthesizing synthetic natural gas having a high calorific value using the catalyst for producing synthetic natural gas.

The catalyst for producing synthetic natural gas according to an embodiment of the present invention is used in a reaction of reacting carbon monoxide and hydrogen to synthesize a high-heat-generating synthetic natural gas containing a paraffinic hydrocarbon having 2 to 4 carbon atoms, and includes an alumina carrier; And a two-component metal catalyst component supported on the alumina support and composed of cobalt oxide and iron oxide.

In one embodiment, the cobalt oxide and the iron oxide may each include Co ₃ O ₄ and Fe ₂ O ₃ .

In one embodiment, the entire amount of Co ₃ O ₄ may be reduced to CoO, and the entire amount of Fe ₂ O ₃ may be reduced to Fe.

In one embodiment, the weight ratio of iron (Fe) to cobalt (Co) in the two-component metal catalyst component may be 2.8 to 3.2.

In one embodiment, the two-component metal catalyst component may include Co incorporated into Fe ₂ O ₃ phase.

The synthesis method of paraffin-based synthetic natural gas having a high calorific value according to an embodiment of the present invention is a synthetic natural high calorific value containing paraffinic hydrocarbons having 2 to 4 carbon atoms by reacting carbon monoxide and hydrogen in the presence of the catalyst for natural gas production. Synthesize gas.

In one embodiment, the ratio of the hydrogen to the carbon monoxide may be 2.0 or more and 4.0 or less.

In one embodiment, the reaction of the carbon monoxide and the hydrogen may be performed at a temperature of 270°C or more and 360°C or less.

According to the catalyst for producing synthetic natural gas having a high calorific value of the present invention and a method for synthesizing a paraffin-based synthetic natural gas with a high calorific value using the same, the reducing property of iron is improved to exhibit a relatively high CO conversion rate, and a paraffinic C2 to C4 type Synthetic natural gas with high calorific value can be produced by containing hydrocarbons in a high proportion.

1 shows the XRD pattern for catalysts before and after reduction.
2 shows the H2-TPR profile of the catalyst.
3 shows the catalyst behavior of catalysts having the same loading amount (20 wt%) or different mass ratios when reduced for 1 hour at 500° C. under 10% H ₂ /N ₂ mixed gas conditions.
Figures 4a to 4c are the activation of the '5Co-15Fe / γ-Al 2 O 3' of the catalyst at different H2 / CO ratio and reaction temperature also test results.
Figure 5 shows a C2 to C4 hydrocarbon selectivity for CO conversion of '5Co-15Fe / γ-Al 2 O 3' catalyst under various reaction temperature and the H2 / CO ratio conditions.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present invention, various modifications may be made and various forms may be applied, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific form of disclosure, it is to be understood as including all changes, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

The terms used in the present application are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the existence of features, steps, actions, components, parts, or a combination thereof described in the specification, but one or more other features or steps It is to be understood that it does not preclude the possibility of addition or presence of, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Does not.

<Catalyst for producing synthetic natural gas with high calorific value>

The catalyst for producing synthetic natural gas according to an embodiment of the present invention can be applied to a reaction of synthesizing synthetic natural gas (SNG) having a high calorific value by reacting carbon monoxide (CO) and hydrogen (H2). For example, the synthetic natural gas having a high calorific value may be a gaseous hydrocarbon containing a paraffinic hydrocarbon having a carbon number of about 2 to 4 in a relatively high proportion.

The catalyst for natural gas production may include a two-component metal catalyst component supported on an alumina support. The alumina carrier may include γ-phase crystalline alumina particles. For example, the alumina carrier may include γ-alumina particles having a size of about 1 to 1000 μm.

In one embodiment, the two-component metal catalyst component may include cobalt oxide and iron oxide. For example, before reduction, the cobalt oxide and iron oxide may each include Co ₃ O ₄ and Fe ₂ O ₃ . Meanwhile, in the two-component metal catalyst component, Co ₃ O ₄ may be reduced to CoO, and Fe ₂ O ₃ may be reduced to Fe.

In one embodiment, the two-component metal catalyst component may have a weight ratio of iron (Fe) to cobalt (Co) of about 2.8 to 3.2. When the weight ratio of iron to cobalt is within the above range, the interaction between Fe and alumina is weakened by the incorporation of Co into the Fe ₂ O ₃ phase, thereby increasing the reducibility of Fe.

<Method of synthesizing high calorific paraffinic synthetic natural gas>

The synthesis method of paraffin-based synthetic natural gas having a high calorific value according to an embodiment of the present invention is a step of reacting carbon monoxide (CO) and hydrogen (H ₂ ) in the presence of the catalyst for producing synthetic natural gas having a high calorific value of the present invention described above. Including, it is possible to produce a hydrocarbon having a high calorific value containing a C2 to C4 paraffinic hydrocarbon gas in a high ratio.

In one embodiment, the carbon monoxide (CO) and the hydrogen (H ₂ ) may be reacted in the chamber, and for this purpose, the ratio of the hydrogen (H ₂ ) to the carbon monoxide (CO) is about The carbon monoxide (CO) and the hydrogen (H ₂ ) may be supplied in a ratio of 2.0 or more and 4.0 or less, preferably about 3.0 or more and 4.0 or less.

In one embodiment, the reaction of the carbon monoxide (CO) and the hydrogen (H ₂ ) may be carried out at a temperature of about 270° C. or more and about 360° C. or less, preferably about 290° C. or more and about 360° C. or less. . When the reaction temperature is less than 270°C, the CO conversion rate may be too low, and when the reaction temperature exceeds 360°C, the C2 to C4 hydrocarbon selectivity and the paraffin ratio may decrease. In one embodiment, the reaction of the carbon monoxide (CO) and the hydrogen (H ₂ ) may be performed at a temperature of about 290°C or more and about 310°C or less.

According to the catalyst for producing synthetic natural gas having a high calorific value of the present invention and a method for synthesizing a paraffin-based synthetic natural gas with a high calorific value using the same, the reducing property of iron is improved to exhibit a relatively high CO conversion rate, and a paraffinic C2 to C4 type Synthetic natural gas with high calorific value containing a high proportion of hydrocarbons can be produced.

Hereinafter, examples and experimental examples of the present invention will be described in detail. However, the following examples are only some embodiments of the present invention, and the scope of the present invention is not limited to the following examples.

<Catalyst synthesis>

Catalysts were synthesized by IWI (Incipient wetness impregnation) method using Co(NO ₃ ) ₂ ·6H ₂ O, Fe(NO ₃ ) ₃ ·9H ₂ O and γ-alumina. The impregnation process for supporting cobalt (Co) and iron (Fe) on γ-alumina was performed according to the following sequence.

Alumina was added together with anhydrous ethanol to a solution containing cobalt nitrate and iron nitrate in a preset ratio, followed by mixing for 24 hours using a magnetic stirrer. After stirring, the solvent was removed at 40 to 60° C. using a rotary evaporator. The samples were dried at 120° C. for 12 hours and calcined at 400° C. for 8 hours by increasing the temperature at a rate of 10° C./min. A binary Co-Fe catalyst supported on γ-alumina, “xCo-yFe/γ-Al2O3” (x, y denotes the mass ratio of each metal) was synthesized.

<Experimental Example>

1 shows the XRD pattern for catalysts before and after reduction.

1, the reduction pre (Fresh) '20Co / γ- Al 2 O 3' and the XRD pattern of _{'20Fe / γ-Al 2 O} 3' catalyst are each a Co ₃ O ₄ phase and a Fe ₂ O ₃ phase Appeared to contain. In the case of a two-metal component catalyst, the XRD peak of Co ₃ O ₄ decreased as the ratio of iron to cobalt increased. The '5Co-15Fe/γ-Al ₂ O ₃ 'catalyst did not show a peak corresponding to Co ₃ O ₄ , whereas a peak corresponding to CoO appeared, indicating that Co was incorporated into Fe ₂ O ₃ after calcining. However, the XRD peak of Fe ₂ O ₃ was found to be very wide compared to that of Co ₃ O ₄ , because the particle size was formed small due to the excellent dispersibility of iron in the γ-alumina phase.

XRD pattern of the XRD pattern of the reduced (Reduced) '20Co / γ- Al 2 O 3' catalyst CoO phase and while showing a Co metal phase, the reduced _{'20Fe / γ-Al 2 O} 3' catalyst is Fe ₃ O ₄ phase and Fe metal phase were shown. In the case of a two-metal component catalyst, as the ratio of iron to cobalt increases, the XRD peak corresponding to the Co metal decreases, and the XRD peak corresponding to the Fe metal increases. In the '5Co-15Fe/γ-Al ₂ O ₃ 'catalyst, XRD peaks corresponding to CoO and Fe metals were shown. As explained above, '5Co-15Fe / γ- Al 2 O 3' weakens the interaction between due to the merging of the phase Co in Fe ₂ O ₃ of iron and alumina in the catalyst, resulting in iron types to be reducible to improve have.

2 shows the H2-TPR profile of the catalyst.

Referring to Figure 2, '20Co / γ-Al 2 O 3' of the catalytic H2-TPR curve represents the second group of peaks made up of a high temperature peak at the lower temperature peak, and 450 to 650 ℃ at 300 to 400 ℃, which It is attributed to the reduction of Co ₃ O ₄ to CoO and the reduction of CoO to metal Co, respectively.

The H2-TPR curve of the '20Fe/γ-Al2O3' catalyst shows a peak at 300 to 400°C and a broad peak at 450 to 700°C, and these are the reduction of Fe ₂ O ₃ to Fe ₃ O ₄ and Fe ₃ O ₄ Respectively due to the reduction of the metal to Fe The FeO phase was not detected as an intermediate phase. It has been found that as the ratio of iron to cobalt increases, the reduction temperature of cobalt shifts to a higher temperature, while the reduction temperature of iron shifts to a lower temperature. Therefore, it is judged that the reduction of cobalt becomes more difficult in the presence of iron, and the reduction of iron is enhanced by the addition of cobalt.

3 shows the catalytic behavior of catalysts having the same loading amount (20 wt%) or different mass ratios when reduced for 1 hour at 500° C. under 10% H ₂ /N ₂ mixed gas conditions, and Table 1 shows The results are shown. The activity test was carried out under conditions of 3 H ₂ /CO ratio at 300° C. and 10 bar.

CO conversion rate
(%) Selectivity (%) CH ₄ C ₂ to C ₄ C ₅₊ CO ₂ 20Co 97.0 42.2 16.7 29.2 11.9 15Co-5Fe 99.1 49.3 19.9 20.7 10.2 10Co-10Fe 95.4 45.0 20.5 18.8 15.6 5Co-15Fe 91.5 23.5 28.2 26.0 22.3 20Fe 54.0 25.4 26.6 26.2 25.4

Referring to Figure 3 and Table 1, showed _{'20Co / γ-Al 2 O} 3' and _{'20Fe / γ-Al 2 O} 3' catalysts for CO conversion of 97.0% and 54.0%, respectively, second metal component catalysts It showed a CO conversion of 91.5% to 99.1%. That is, the two metal component catalysts exhibited higher CO conversion than the '20Fe/γ-Al ₂ O ₃ 'catalyst. This improvement in CO conversion is consistent with improved iron reducibility. _{'20Co / γ-Al 2 O} 3' catalyst having 2 or more (C ₂₊₎ of exhibited a higher selectivity to methane than the _{hydrocarbon, '20Fe / γ-Al 2} O 3' catalyst is relatively low methane Selectivity and relatively higher selectivity for hydrocarbons having 2 or more carbon atoms (C ₂₊ ) and CO ₂ selectivity were shown. It is well known that iron catalysts have a lower degree of activation than cobalt catalysts, lower methane selectivity at high temperatures, and higher olefin content. In addition, the high CO ₂ selectivity of the iron catalyst causes a water-gas change reaction (WGS, CO+H ₂ O->CO ₂ +H ₂ ). In contrast, the two metal component catalyst exhibits intermediate product selectivity compared to the one metal component catalyst. In particular, as the ratio of iron to cobalt increases, methane selectivity decreases and hydrocarbon production of C2 to C4 increases. Among all catalysts, the '5Co-15Fe/γ-Al ₂ O ₃ 'catalyst showed the highest C2 to C4 paraffin selectivity (28.2%) at a high CO conversion rate (91.5%). As compared to the _{'20Fe / γ-Al 2 O} 3' catalyst, and '5Co-15Fe / γ-Al 2 O 3' high conversion and similar selectivity of the catalyst resulting from an improved iron-reducing.

Figures 4a to 4c and Table 2 are the activation of the '5Co-15Fe / γ-Al 2 O 3' of the catalyst at different H2 / CO ratio and reaction temperature also test results.

H2/CO Temperature
(℃) CO conversion rate
(%) Selectivity (%) P/(P+O) CH4 C2~C4
Paraffins C2~C4
Olefins C5+ CO2 1.0 250 18.5 20.0 7.6 10.9 41.8 19.7 0.41 300 36.7 22.6 13.2 7.2 28.4 28.6 0.65 350 52.3 19.9 9.2 6.4 30.1 34.5 0.59 400 93.7 19.7 8.8 2.7 33.6 35.3 0.77 2.0 250 45.1 23.7 13.5 10.5 26.6 25.7 0.56 300 43.8 26.9 24.0 1.6 23.3 24.2 0.94 350 70.9 25.8 18.4 2.9 22.3 30.5 0.86 400 90.0 33.6 14.8 2.2 22.0 27.5 0.87 3.0 250 55.6 31.9 16.5 8.5 17.9 25.3 0.66 300 91.5 23.5 27.6 0.6 26.0 22.3 0.98 350 96.4 33.5 22.0 2.1 14.8 27.6 0.91 400 98.5 44.6 16.7 2.7 12.6 23.4 0.86

Referring to FIG. 4A and Table 2, it was found that the CO conversion rate significantly increased with temperature at all H ₂ /CO ratios. In addition, it was shown that the CO conversion was improved at higher H ₂ /CO ratios up to 400°C. From these, it can be seen that the H ₂ /CO ratio and temperature play an important role in improving the CO conversion rate.

Referring to FIG. 4B and Table 2, it was found that all H ₂ /CO ratios exhibited a similar trend according to the reaction temperature. C2 to C4 selectivity was found to increase with increasing temperature up to 300°C, but decreased with increasing temperature at higher temperatures. In addition, C2 to C4 selectivity was found to be improved as the H ₂ /CO ratio increased, but this effect was found to be small when the H ₂ /CO ratio exceeded 2.0. '5Co-15Fe / γ-Al 2 O 3' catalyst exhibited a 28.2% of a C2 to C4 selectivity under the condition of a reaction temperature of 300 ℃ 3.0 and H ₂ / CO ratio. It was found that the reaction temperature had a greater effect on the C2 to C4 selectivity than the H ₂ /CO ratio.

4C and Table 2, the proportion of paraffin among C2 to C4 hydrocarbons exhibited a similar trend to the C2 to C4 selectivity shown in FIG. 4B. At H ₂ /CO ratios of 3.0 and 2.0, the paraffin ratio was found to increase with increasing temperature up to 300°C, but at higher temperatures it was found to decrease with increasing temperature. However, in the case of the H ₂ /CO ratio of 1.0, it was found that the paraffin ratio increased as the temperature increased in the section where the temperature was 350°C or higher. And it was found that the paraffin ratio improved as the H ₂ /CO ratio increased, but this effect was found to be small when the H ₂ /CO ratio exceeded 2.0. The fact that the effect of the H ₂ /CO ratio is small in the region exceeding 2.0 is that WGS (water gas shift, CO+H ₂ O->CO ₂ +H ₂ ) reaction proceeds by the water generated as the reaction proceeds. This is believed to be due to the effect of the readjustment of the H ₂ /CO ratio.

In summary, when the '5Co-15Fe/γ-Al ₂ O ₃ 'catalyst is applied, the H2/CO ratio is preferably 3.0 or more, and the reaction temperature is preferably 290°C or more and 360°C or less.

Figure 5 shows a C2 to C4 hydrocarbon selectivity for CO conversion of '5Co-15Fe / γ-Al 2 O 3' catalyst under various reaction temperature and the H2 / CO ratio conditions.

Referring to FIG. 5, the results at a H2/CO ratio of 3.0 and a reaction temperature of 300° C. or higher show high C2 to C4 paraffin selectivity as well as high CO conversion.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the present invention described in the following claims. You will understand that you can.

none

Claims (8)

In the catalyst used in the reaction of reacting carbon monoxide and hydrogen to synthesize a high-heat synthetic natural gas containing a paraffinic hydrocarbon having 2 to 4 carbon atoms,
Alumina carrier; And
A catalyst for producing synthetic natural gas, which is supported on the alumina support and comprises a two-component metal catalyst component consisting of cobalt oxide and iron oxide. The method of claim 1,
The cobalt oxide and the iron oxide are Co ₃ O ₄ and Fe ₂ O ₃ , characterized in that each containing, synthetic natural gas production catalyst. The method of claim 2,
The total amount of Co ₃ O ₄ may be reduced to CoO, and the total amount of Fe ₂ O ₃ may be reduced to Fe, a catalyst for producing synthetic natural gas. The method of claim 1,
A catalyst for producing synthetic natural gas, characterized in that the weight ratio of iron (Fe) to cobalt (Co) in the two-component metal catalyst component is 2.8 to 3.2. The method of claim 4,
The two-component metal catalyst component is characterized in that it comprises Co incorporated into the Fe ₂ O ₃ phase, a catalyst for producing synthetic natural gas. Claims 1 to 5 characterized in that by reacting carbon monoxide and hydrogen in the presence of the catalyst for natural gas production according to any one of claims 1 to 5 to synthesize a high-heat synthetic natural gas containing a paraffinic hydrocarbon having 2 to 4 carbon atoms. A method for synthesizing caloric paraffinic synthetic natural gas. The method of claim 6,
The method of synthesizing a high calorific paraffin-based synthetic natural gas, characterized in that the ratio of the hydrogen to the carbon monoxide is 2.0 or more and 4.0 or less. The method of claim 6,
The reaction of the carbon monoxide and the hydrogen is characterized in that carried out at a temperature of not less than 270 ℃ 360 ℃, synthesis method of high calorific paraffin-based synthetic natural gas.

Images