阅读说明：本技术 水蒸气重整催化剂 (Steam reforming catalyst ) 是由 冈田治 本村加奈 宫田纯弥 高田智夏 桑迫逸郎 河野真奈美 于 2019-06-11 设计创作，主要内容包括：本发明的课题是：提供一种耐碳析出性和耐烧结特性优异的Ni系的水蒸气重整催化剂。技术手段是：水蒸气重整催化剂包含以下成分而构成：作为催化活性金属的镍、作为第一助催化剂成分的镧、作为第二助催化剂成分的锰、和含有γ-氧化铝作为主成分的载体。(The subject of the invention is: provided is a Ni-based steam reforming catalyst having excellent carbon deposition resistance and sintering resistance. The technical means is as follows: the steam reforming catalyst is composed of the following components: nickel as a catalytically active metal, lanthanum as a first promoter component, manganese as a second promoter component, and a carrier containing gamma-alumina as a main component.)

1. A steam reforming catalyst, comprising: nickel as a catalytically active metal, lanthanum as a first promoter component, manganese as a second promoter component, and a carrier containing gamma-alumina as a main component.

2. The steam reforming catalyst of claim 1, wherein, relative to the combined weight of the catalytically active metal, the first promoter component, the second promoter component, and the support,

the content of the catalytically active metal is 11 to 18 wt%,

a content of the first co-catalyst component is 8 to 12 wt%,

the content of the second co-catalyst component is 0.05 to 3 wt%.

3. The steam reforming catalyst according to claim 1 or 2, wherein the amount of the catalyst component in the catalyst component is less than the total weight of the catalytically active metal, the first promoter component, the second promoter component, and the carrier,

the total content of the first co-catalyst component and the second co-catalyst component is 10.05 wt% or more and 15 wt% or less.

4. The steam reforming catalyst according to any one of claims 1 to 3, wherein the catalyst composition further comprises, based on the total weight of the catalytically active metal, the first promoter component, the second promoter component and the carrier,

the total content of the catalytically active metal and the second promoter component is 11.05 wt% or more and 21 wt% or less.

5. The steam reforming catalyst according to any one of claims 1 to 4, wherein the weight ratio of the first promoter component to the catalytically active metal is 50% or more and 120% or less.

6. The steam reforming catalyst according to any one of claims 1 to 5, wherein the weight ratio of the second promoter component to the catalytically active metal is 0.33% or more and 20% or less.

Technical Field

The present invention relates to a steam reforming catalyst used in a steam reforming system for producing hydrogen by reforming a hydrocarbon-based raw material gas and steam into carbon monoxide and hydrogen.

Background

As one of energy technologies using hydrogen with a small environmental load, a fuel cell that generates electric energy by reacting hydrogen with oxygen has attracted attention. As the hydrogen source of the fuel cell, various hydrocarbon-based materials such as natural gas and coal-based hydrocarbons can be used, and in particular, hydrocarbons such as city gas, LP gas, naphtha, gasoline, and kerosene, which are supplied to infrastructure equipment, can be suitably used. These hydrocarbon-based raw materials are subjected to a reforming reaction with steam in the presence of a steam reforming catalyst to produce a synthesis gas of carbon monoxide and hydrogen, and the carbon monoxide in the synthesis gas is removed by a shift reaction treatment, a selective oxidation treatment, or the like, thereby producing hydrogen.

As steam reforming catalysts, Ni catalysts using nickel (Ni) as a catalytically active metal and noble metal catalysts using noble metals such as ruthenium (Ru) as a catalytically active metal have been put to practical use (see patent documents 1 and 2, etc.).

The Ni catalyst is generally widely used as an industrial steam reforming catalyst and a partial oxidation/autothermal reforming catalyst, and the Ni metal itself is widely used in practice and in the world by adding potassium (K) and magnesium (Mg) having a carbon deposition-suppressing effect as promoters because carbon deposition is remarkable under reforming reaction conditions (particularly, natural gas containing naphtha, LP gas, and heavy hydrocarbons) regardless of the supported catalyst, impregnated catalyst, and kneaded catalyst (see patent document 3 and the like).

However, in the future, in order to further improve the energy efficiency of the hydrogen production process, it is desired to operate under lower S/C conditions that are more severe than those of the prior art (S/C: carbon (C) in the raw hydrocarbon of the hydrogen production process and raw steam (H)₂O) molar ratio) of the catalyst, the high-efficiency low S/C condition cannot be adopted due to the risk of carbon deposition of the Ni-based steam reforming catalyst, which is the main stream in the conventional hydrogen production process. In this case, since the carbon deposition inhibiting effect of the existing industrial Ni catalyst is insufficient, a Ru catalyst having excellent carbon deposition resistance has been put to practical use particularly in a Substitute Natural Gas (SNG) production process for a city gas business where strict operation is desired.

In addition, the Ru catalyst is also superior in sintering resistance to the Ni catalyst. Therefore, if a high-performance desulfurization technique is employed to completely prevent sulfur poisoning, a compact reactor and a long service life can be achieved at the same time, and therefore, application of the Ru catalyst to a reformer for a fuel cell, in which the catalyst replacement cycle is expected to be 5 years or more, is being promoted.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2-43952

Patent document 2: japanese laid-open patent publication No. 8-231204

Patent document 3: japanese patent laid-open publication No. 2017-29970

Disclosure of Invention

Problems to be solved by the invention

In the field of energy such as fuel cell vehicles and household fuel cells, the use of hydrogen is expected to increase rapidly in the future. However, in this hydrogen production system, a large amount of rare and expensive precious metals are used, and development of a technique for reducing the amount of precious metals is urgent. In particular, Ru is produced in a small amount by one order of magnitude in the platinum group metal, and is used in a large amount in the future, because Ru has excellent characteristics as a reforming catalyst for hydrogen production, and thus its use as a reforming catalyst for fuel cells requiring high performance is rapidly increasing. For example, an annual output (20t) of Ru is consumed by a reforming catalyst of 400 kW only for a home fuel cell.

In the case of an Ni-based catalyst in which a conventional co-catalyst is added to improve the carbon deposition resistance and the sintering resistance to the same extent as those of a Ru catalyst, the Ni-based catalyst can replace the Ru catalyst and can stably provide a high-performance steam reforming catalyst without being affected by the resource restriction of Ru.

The present invention has been made in view of the above problems, and an object thereof is to provide a Ni-based steam reforming catalyst having excellent carbon deposition resistance and sintering resistance.

Means for solving the problems

The steam reforming catalyst of the present invention is characterized by comprising: nickel as a catalytically active metal, lanthanum as a first promoter component, manganese as a second promoter component, and a carrier containing gamma-alumina as a main component.

Further, the steam reforming catalyst of the above-described characteristic is preferably: relative to the combined weight of the catalytically active metal, the first promoter component, the second promoter component and the support,

the content of the catalytically active metal is 11 to 18 wt%,

a content of the first co-catalyst component is 8 to 12 wt%,

the content of the second co-catalyst component is 0.05 to 3 wt%.

Further, the steam reforming catalyst of the above-described characteristic is preferably: the total content ratio of the first promoter component and the second promoter component is 10.05 wt% or more and 15 wt% or less with respect to the total weight of the catalytically active metal, the first promoter component, the second promoter component, and the carrier.

Further, the steam reforming catalyst of the above-described characteristic is more preferably: the total content ratio of the catalytically active metal and the second promoter component is 11.05 wt% or more and 21 wt% or less with respect to the total weight of the catalytically active metal, the first promoter component, the second promoter component, and the carrier.

Further, the steam reforming catalyst of the above-described characteristic is preferably: the weight ratio of the first promoter component to the catalytically active metal is 50% or more and 120% or less.

Further, the steam reforming catalyst of the above-described characteristic is preferably: the weight ratio of the second promoter component to the catalytically active metal is 0.33% or more and 20% or less.

Effects of the invention

According to the steam reforming catalyst of the present invention, the nickel as the catalytically active metal and 2 metals of lanthanum and manganese as the co-catalyst are present as an aggregate on the support containing γ -alumina as the main component, whereby the reduction of the catalytic activity of nickel is suppressed, a high hydrocarbon conversion rate comparable to that of the Ru catalyst can be achieved, and carbon deposition, sintering (aggregation) of the catalytically active metal, and the like, which are factors of the reduction of the catalytic activity, are suppressed as compared with the case of using other metals as the co-catalyst, and a high-performance Ni-based steam reforming catalyst can be provided.

Drawings

Fig. 1 is a list showing the results of performance evaluation of comparative samples a1 to a6 to which no manganese was added.

Fig. 2 is a list showing the results of performance evaluation performed on comparative samples B0 to B5 to which no manganese was added.

Fig. 3 is a list of performance evaluation results of comparative samples C1 to C4, comparative ruthenium catalyst X1, and comparative industrial nickel catalyst X2, to which no manganese was added.

FIG. 4 shows the evaluation of C1-C5 for 96 hours at a reaction temperature of 450 ℃ for comparative samples containing no manganese₃H₈Graph of results for conversion.

Fig. 5 is a list showing the results of performance evaluation performed on comparative sample C3 to which no manganese was added, samples D1 to D7 of the steam reforming catalyst of the present invention, and comparative ruthenium catalyst X1.

Fig. 6 is a list showing performance evaluation results of samples E1 to E6 of the steam reforming catalyst of the present invention and a comparative ruthenium catalyst X1.

Fig. 7 is a list showing the results of performance evaluation of comparative samples F1 to F9, in which metals other than manganese were added as the second promoter component, sample E2 of the steam reforming catalyst of the present invention, and comparative ruthenium catalyst X1.

FIG. 8 shows C which was evaluated continuously for 96 hours for samples E1 to E3 of the steam reforming catalyst of the present invention, comparative samples F9 to F11 in which tungsten was added as a second promoter component, and comparative ruthenium catalyst X1₃H₈Graph of results for conversion.

Fig. 9 is a list showing performance evaluation results of samples D2 and E2 of the steam reforming catalyst of the present invention and comparative samples G1 to G4 using a carrier containing α -alumina as a main component.

FIG. 10 shows C in 1000-hour continuity evaluated on a sample E2 of the steam reforming catalyst of the present invention, a sample C3 without manganese added for comparison, and a ruthenium catalyst X1 for comparison₃H₈Graph of results for conversion.

Detailed Description

A preferred embodiment of the steam reforming catalyst of the present invention (hereinafter, referred to as "the present embodiment" as appropriate) will be described.

The steam reforming catalyst of the present embodiment (hereinafter, referred to as "present catalyst" as appropriate) is a catalyst that promotes a steam reforming reaction in which steam is brought into contact with hydrocarbons to generate a synthesis gas containing carbon monoxide and hydrogen. The steam reforming reaction includes an autothermal reforming reaction in which a partial oxidation reaction is accompanied by an oxygen-containing gas during the reaction with steam. Examples of the hydrocarbon include hydrocarbon gases having 1 to 4 carbon atoms such as methane, ethane, propane, and butane, and alcohols such as methanol, ethanol, and propanol. The raw gas for the steam reforming reaction using the present catalyst is not limited to the above-described hydrocarbon examples.

The catalyst comprises nickel as a catalytically active metal, lanthanum as a first promoter component, manganese as a second promoter component, and a carrier containing gamma-alumina as a main component. Nickel, lanthanum and manganese are dispersed and supported on the same carrier in the form of particles, and exist as an aggregate.

As will be described later, the present inventors have made intensive studies and found that: since lanthanum and manganese are present on the same support as nickel, which is a catalytically active metal, the functions of the promoter for suppressing carbon deposition, which is a main factor of lowering the catalytic activity, and sintering of the catalytically active metal are improved as compared with the case where lanthanum is used alone as the promoter. The present catalyst is based on the results of this study by the present inventors.

The carrier of the present catalyst contains γ -alumina as a main component (for example, 80 wt% or more and 100 wt% or less), and may contain a trace amount of an inorganic oxide (α -alumina, silica (silica), zirconia (zirconia), titania (titania), lanthanum oxide, calcium oxide, or the like) or a trace amount of an impurity element (sulfur, potassium, iron, or the like) in addition to γ -alumina. The total content of inorganic oxides other than gamma-alumina is preferably about 0 to 10 wt%, and the total content of impurity elements is preferably 1 wt% or less, with respect to the total weight of the carrier. The BET specific surface area of the carrier is not particularly limited, and is preferably 90 to 300m in order to sufficiently disperse the 3 components of nickel, lanthanum and manganese supported thereon²And about/g.

In the present embodiment, the γ -alumina of the carrier is a powdery material, may be a needle-like or fibrous material in the form of a block, or may be a mixture of powdery, needle-like or fibrous materials.

The content of nickel is preferably about 11 to 18 wt%, more preferably about 13 to 17 wt%, based on the total weight of the 3 components of nickel, lanthanum and manganese and the carrier (hereinafter referred to as the "total weight of the catalyst"). If the content of nickel is increased to more than 18 wt% based on the total weight of the catalyst, dispersibility is impaired, and the proportion of the active metal exposed on the surface by aggregation is reduced, resulting in a reduction in catalytic activity. When the content of nickel is reduced to less than 11 wt% based on the total weight of the catalyst, the catalytic activity is reduced due to a reduction in the amount of nickel supported.

The lanthanum content is preferably about 8 to 12 wt%, more preferably about 10 to 12 wt%, based on the total weight of the catalyst. The manganese content is preferably about 0.05 to 3 wt%, more preferably about 0.5 to 2.5 wt%, and still more preferably about 1 to 1.5 wt% based on the total weight of the catalyst.

If the lanthanum content increases to more than 12 wt% based on the total weight of the catalyst, dispersibility is impaired, and the proportion of the promoter component exposed to the surface by aggregation decreases, resulting in a decrease in the function as a promoter. When the lanthanum content is reduced to less than 8 wt% based on the total weight of the catalyst, the function as a promoter is reduced due to the reduction in the amount of lanthanum supported. If the content of manganese increases and exceeds 3 wt% based on the total weight of the catalyst, dispersibility is impaired and the proportion of the promoter component exposed on the surface by aggregation is reduced, resulting in a reduction in the function as a promoter. When the content of manganese is reduced to less than 0.05 wt% based on the total weight of the catalyst, the function as a promoter is reduced due to the reduction in the amount of manganese supported.

The total content of the 2 components of nickel and manganese is preferably about 11.05 to 21 wt%, more preferably about 11.05 to 18 wt%, and still more preferably 13 to 17 wt% based on the total weight of the catalyst. The total content of 2 components, i.e., lanthanum and manganese, is preferably about 8.05 to 15 wt%, more preferably about 10.05 to 15 wt%, and still more preferably 10.5 to 14.5 wt%, based on the total weight of the catalyst.

The weight ratio of lanthanum to nickel (La/Ni) is preferably about 50% to 120%, more preferably about 75% to 100%. The weight ratio of manganese to nickel (Mn/Ni) is preferably about 0.33% to 20%, more preferably about 3.33% to 20%, and still more preferably about 6.66% to 15%.

Next, a method for producing the catalyst will be described by taking a known impregnation method (the same as the evaporation and drying method) as an example. The method for producing the catalyst is not limited to the impregnation method, and a neutralization method or the like may be used.

First, a mixed solution is prepared by dissolving a nickel compound, a lanthanum compound, and a manganese compound in a solvent such as water, ethanol, or acetone. As each compound of nickel, lanthanum and manganese, nitrate, acetate, sulfate, acetoacetate, hydroxide, chloride and the like are used, and particularly, nitrate and acetate can be suitably used.

Next, a carrier such as a powder is added to the mixed solution, the mixture is stirred by an evaporator to evaporate the solvent, and then the mixture is dried by evaporation at a predetermined temperature (for example, 80 to 120 ℃) and finally subjected to firing at a predetermined temperature (for example, 400 to 700 ℃) to prepare the catalyst. The drying atmosphere and the firing atmosphere are preferably in the air. The powdery carrier is preferably sieved in advance so that the particle size thereof falls uniformly within a predetermined range (for example, about 200 μm or less).

The amount of each of the 3 compounds is set so that the content of each of the 3 components, i.e., nickel, lanthanum, and manganese, is equal to the content (wt%) of the oxide (nickel oxide, lanthanum oxide, and manganese oxide) after the firing treatment. That is, the content of each of the 3 components is the content (value in terms of oxide) of each of the 3 oxides of the 3 components, and the weight of each of the 3 components constituting the total weight of the catalyst is also the weight of each of the 3 oxides of the 3 components.

The present catalyst immediately after the preparation by the above-mentioned preparation method is preferably subjected to reduction treatment in a hydrogen atmosphere or a hydrogen-containing atmosphere before the use of the present catalyst because all or part of nickel, lanthanum and manganese supported on the carrier are present in the form of oxides (nickel oxide, lanthanum oxide and manganese oxide).

For example, when nickel nitrate, lanthanum nitrate, and manganese nitrate are used as the nickel compound, lanthanum compound, and manganese compound, 50ml of 500mM nickel nitrate aqueous solution, 13.35ml of 500mM lanthanum nitrate aqueous solution, 5.94ml of 500mM manganese nitrate aqueous solution, and 69ml of pure water (equivalent to the total amount of nickel nitrate aqueous solution, lanthanum nitrate aqueous solution, and manganese nitrate aqueous solution) are mixed with 8.15g of the carrier so that the content ratios of nickel, lanthanum, and manganese are 13.5 wt%, 10 wt%, and 1.5 wt%, respectively, to prepare the mixed solution. When the content of each of the 3 components is changed from the above value, the amount of each aqueous solution may be appropriately adjusted. The concentration of each aqueous solution and the amount of pure water may be appropriately changed.

[ evaluation results of catalytic Properties ]

Next, the evaluation results of the catalytic performance of the present catalyst will be described. The catalytic performance was evaluated based on C in the case where the raw material gas for the steam reforming reaction was propane₃H₈Conversion, H₂Adsorption and the amount of coking (amount of precipitated carbon) were carried out in 3 items.

The evaluation of the catalytic performance was specifically carried out in each of the studies described below, including the study of the appropriate range of the content of nickel and lanthanum with respect to the total weight of the catalyst, the study of the appropriate range of the content of manganese with respect to the total weight of the catalyst, the study of the most appropriate manganese as the second promoter, the study of the carrier component, and the study of the long-term stability. Therefore, the overlapping description of the evaluation method is omitted in each study item.

With respect to C₃H₈Conversion rate, using a catalytic activity evaluation device manufactured by Hemmi Slide Rule co.ltd and a TCD (thermal conductivity detector) Model-802 manufactured by a large-scale technical study (currently Hemmi Slide Rule co.ltd) as a gas chromatograph, 0.5g of a catalyst was previously charged in a reaction tube, and reduction treatment was performed with hydrogen gas at 600 ℃ for 1 hour to reduce N₂、C₃H₈、H₂、H₂A mixed gas (supply gas) of O (water vapor) is supplied into the reaction tube and passed therethrough, and after being held at a predetermined reaction temperature (for example, 400 ℃, 450 ℃, 500 ℃, 600 ℃ or the like) for 1 hour, the generated gas (CO) is measured by a gas chromatograph₂、C₂H₄、C₂H₆、C₃H₈、H₂、N₂、CO、CH₄) The concentration of (b) is calculated by the following equation 1. It is required to be noted thatThe supply conditions for the gas were as follows: n is a radical of₂：60ml/min，C₃H₈：60ml/min，H₂：6ml/min，H₂O: 360ml/min, Space Velocity (SV) 60000, and S/C2.0.

[ numerical formula 1]

C₃H₈Conversion (%) (% of C in the feed gas)₃H₈Concentration (%) -C in the generated gas₃H₈Concentration (%)/(C in feed gas)₃H₈Concentration (%). times.100

H₂For the adsorption evaluation, about 0.15g of a catalyst was charged into a sample tube using a catalyst analyzer (BEL-CAT) manufactured by Nippon BEL co.ltd. (currently microtrac BEL co.ltd.), the inside of the sample tube was replaced with Ar gas, and then H was introduced at 600 ℃₂Pulse to measure H of nickel₂Unit adsorption capacity (cm)³Per gram), metal dispersion (%), and average particle size (nm).

In the evaluation of the amount of coking, a sample was burned in a high-temperature furnace using a carbon-sulfur analyzer CS744 manufactured by LECO Japan Joint Company, the concentration of carbon contained in the sample was measured, and the carbon concentration (% by weight) was calculated from the ratio of the weight of carbon in the sample to the weight of the sample before combustion as the amount of coking (%).

[ examination of suitable ranges for the content of Nickel and the content of lanthanum ]

In the following description, for convenience of explanation, the content of each component of nickel, lanthanum and manganese or the content of 2 or more components based on the total weight of the catalyst is simply referred to as "content" or "total content".

In the present catalyst, since the content of manganese is smaller than that of nickel and lanthanum as described above, in a state where no manganese is added (the content of manganese is 0 wt%), an appropriate range of each content of nickel and lanthanum is first roughly studied. In this study, a total of 16 samples were prepared: samples A1 to A6 in which the lanthanum content was fixed at 5 wt% and the nickel content was varied from 2 to 20 wt%; samples B0 to B5 in which the content of nickel was fixed at 10 wt% and the content of lanthanum was varied from 0 to 20 wt%; samples C1 to C4 in which the lanthanum content was fixed at 10 wt% and the nickel content was varied from 10 to 20 wt%. Further, as comparative samples for samples C1 to C4, a commercially available ruthenium catalyst X1 (ruthenium-supported amount: 2% by weight, carrier: γ -alumina) and a commercially available industrial nickel catalyst X2 (NiCa-based catalyst, nickel-supported amount: 17 to 18% by weight, carrier: α -alumina) were prepared.

In the present study, C was performed₃H₈Conversion, H₂Adsorption evaluation and coking amount evaluation these 3 evaluations. Wherein, the samples A1-A6, B0-B5, H₂Evaluation of adsorption Only H was evaluated₂Unit adsorption amount.

Samples a1 to a6, B0 to B5, and C1 to C4 were each a catalyst prepared by the above-described method for preparing the present catalyst (impregnation method). The mixed solution is a solution obtained by mixing a nickel nitrate aqueous solution and a lanthanum nitrate aqueous solution in predetermined amounts so that the contents of nickel and lanthanum become predetermined values, and the carrier is a carrier having a content of gamma-alumina of 96 wt% or more, a content of silica of about 3 wt%, and a BET specific surface area of about 180 to 200m²About/g of a gamma-alumina carrier was dried at 80 ℃ for 16 hours in advance, and then the carrier was sieved so that the particle size was about 200 μm or less, and the carrier was added to the mixed solution in an amount such that the content of nickel and lanthanum became a predetermined value.

FIG. 1 shows the contents of nickel and lanthanum, and C in samples A1 to A6₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃, 600 ℃), C₃H₈H before initial evaluation of conversion (hereinafter, simply referred to as "initial evaluation")₂The results of evaluation of the unit adsorption amount and the coking amount after the initial evaluation are summarized in a list of results. The nickel contents of samples a1 to a6 were 2 wt%, 5 wt%, 8 wt%, 10 wt%, 15 wt%, and 20 wt%, respectively, and the lanthanum content was fixed at 5 wt%.

From the results shown in FIG. 1, it is understood that H is increased when the content of nickel is increased₂Unit amount of adsorption andinitial evaluation of C₃H₈The conversion rate also increased, and when the content of nickel exceeded 10 wt%, the coking amount after the initial evaluation increased rapidly. From the results, it is clear from H₂Unit adsorption amount and C₃H₈From the viewpoint of conversion, it is preferable to set the content of nickel to 10% by weight or more, but in order to set the content of nickel to more than 10% by weight, if the coking inhibition effect of lanthanum shown in fig. 2 described later is taken into consideration, the content of lanthanum to 5% by weight is too small. That is, the lower limit of the preferable range of the weight ratio of lanthanum to nickel is 50% or more.

FIG. 2 shows the contents of nickel and lanthanum, and C in samples B0 to B5₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), and H before initial evaluation₂The results of evaluation of the unit adsorption amount and the coking amount after the initial evaluation are summarized in a list of results. The lanthanum contents of samples B0 to B5 were 0 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, and 20 wt%, respectively, and the nickel content was fixed at 10 wt%.

According to the results shown in FIG. 2, regarding C₃H₈The conversion (initial evaluation) showed high catalytic activity without a large difference between the respective reaction temperatures in samples B1 to B4 (lanthanum content of 5 wt% to 12 wt%), but the catalytic activity decreased in sample B0 (lanthanum content of 0 wt%: lanthanum was not added), and the catalytic activity decreased when the lanthanum content increased to 20 wt% (sample B5). H before initial evaluation₂The unit adsorption amount was the highest when the lanthanum content was 8% by weight, and when the lanthanum content exceeded 8% by weight, H was observed₂The unit adsorption amount tends to decrease. With respect to the coking amount after the initial evaluation, it is found that sample B0 (lanthanum content 0 wt%: lanthanum not added) is very large, and coking is greatly suppressed by the addition of lanthanum. In particular, the coking amount was the smallest at a lanthanum content of 10 wt% (sample B3).

FIG. 3 shows the contents of nickel and lanthanum in samples C1 to C4, and C1 to C4 in samples C and comparative samples X1 and X2₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), and H before initial evaluation₂Adsorption (H)₂The results of evaluation of the unit adsorption amount, metal dispersion degree, average particle diameter), and the coking amount after the initial evaluation are summarized in a table. Note that, in the case of the ruthenium catalyst X1, H was replaced₂Adsorption evaluation for CO adsorption evaluation. The nickel contents of samples C1 to C4 were 10 wt%, 12 wt%, 15 wt%, and 20 wt%, respectively, and the lanthanum content was fixed at 10 wt%.

From the results shown in FIG. 3, C of samples C1 to C4 was initially evaluated₃H₈The conversion reached 100% at reaction temperatures of 500 ℃ and 600 ℃ and was higher than 93.5% (500 ℃) and 99.04% (600 ℃) of the ruthenium catalyst X1, and was higher than 69.73% of the ruthenium catalyst X1 except for sample C1 (nickel content: 10% by weight) even at a reaction temperature of 400 ℃ and was only slightly lower than that of the ruthenium catalyst X1 in sample C1, and was approximately the same degree. At a reaction temperature of 400 ℃, as the content of nickel increases from 10 wt% to 15 wt%, C₃H₈Conversion also increased, but when increased to 20 wt%, C₃H₈The conversion rate is rather reduced. Therefore, considering C at a reaction temperature of 400 ℃₃H₈The upper limit of the conversion, which is a suitable range for estimating the nickel content, is present between 15 wt% and 20 wt% (e.g., around 17.5 wt%), and the lower limit thereof is present between 10 wt% and 12 wt%. Therefore, a suitable range of the content of nickel is estimated to be 11 wt% to 18 wt%, more preferably 13 wt% to 17 wt%, and the optimum value of the content of nickel is estimated to be about 15 wt%.

H before initial evaluation of samples C1 to C4₂Adsorption evaluation result, H₂The specific adsorption amount naturally increases with the increase in the content of nickel, but the metal dispersion and the average particle diameter show the best results when the content of nickel is 15 wt%. Therefore, it is found that the upper limit of the suitable range of the content of nickel is higher than 15% by weight and the lower limit thereof is lower than 15% by weight, and C at 400 ℃ considering the reaction temperature₃H₈In the case of conversionThe suitable range of the content of nickel is in agreement.

The coking amount after the initial evaluation naturally increases with the increase in the content of nickel, and when the content of nickel is 12 wt% or more, the coking amount is larger than that of the ruthenium catalyst X1, and is about 1.8 times in sample C2 (content of nickel: 12 wt%), about 1.9 times in sample C3 (content of nickel: 15 wt%), and about 2.7 times in sample C3 (content of nickel: 20 wt%). However, in samples C1 to C4 having a lanthanum content of 10 wt%, even if the content of nickel exceeds 10 wt%, the sharp increase in the amount of coking can be sufficiently suppressed, as compared with samples a1 to a6 having a lanthanum content of 5 wt%.

When the results of evaluating the coking amounts of the samples C1 to C4 shown in fig. 3 and the results of evaluating the coking amounts shown in fig. 2 are combined, a suitable range of the lanthanum content is estimated to be 8 wt% to 12 wt%, more preferably 10 wt% to 12 wt%. Further, when the evaluation results shown in fig. 1 to 3 are comprehensively evaluated, the appropriate range of the weight ratio of lanthanum to nickel is estimated to be 50% to 120%, and more preferably 75% to 100%.

However, in samples C2 to C4 in which manganese was not added as the second promoter component, even if the content of nickel and the content of lanthanum were within appropriate ranges, the coking amount was as high as about 2 times that of the ruthenium catalyst X1, and therefore, as will be described later, manganese was required to be added as the second promoter component in order to suppress the coking amount to the same extent as that of the ruthenium catalyst X1.

Next, fig. 4 shows that, in addition to samples C1 and C3, sample C5 (prepared by the same preparation method as samples C1 to C4) having a nickel content of 8 wt% and a lanthanum content of 10 wt% was added, and C at a reaction temperature of 450 ℃ was continuously evaluated (8 times per 12 hours) for 96 hours together with comparative samples X1 and X2₃H₈Results from conversion. The vertical axis of the graph of FIG. 4 is C₃H₈Conversion (%), and the horizontal axis represents elapsed time. C₃H₈The conditions for evaluating the conversion rate were, except for the reaction temperature, the same as those for C1 to C4 which were initially evaluated in the samples C1 to C4 shown in FIG. 3₃H₈The conditions for evaluating the conversion rate were the same.

According to the results shown in FIG. 4, C was measured for up to 96 hours at a reaction temperature of 450 ℃₃H₈Conversion, not only sample C3 but also sample C1 was compared to C of ruthenium catalyst X1₃H₈The conversion was high, and even in the evaluation up to 96 hours, sample C3 was the highest evaluation. C for additional sample C5₃H₈The conversion rate was significantly lower than that of the ruthenium catalyst X1 because the nickel content was as low as 8 wt%.

[ study on an appropriate range of manganese content ]

Next, the following samples were used to conduct a study of an appropriate range of the manganese content: samples D1 to D7 in which the content of manganese was varied between 0.05 wt% and 2 wt% for a combination of 15 wt% and 10 wt% which is considered to be the optimum combination of the content of nickel and lanthanum; samples E1 to E3 in which a part of the content of nickel (varying between 0.75% and 3% by weight) was replaced with manganese for a combination of 15% and 10% by weight of the content of nickel and lanthanum; samples E4 to E6 in which a part of the content of nickel (varying between 0.5 wt% and 2 wt%) was replaced with manganese for a combination of 10 wt% and 10 wt% of the content of nickel and lanthanum. In the present study, C was performed₃H₈Conversion, H₂Evaluation of adsorption (H)₂Unit adsorption amount), and coking amount.

Samples D1 to D7 and E1 to E6 were prepared by the above-described method for preparing the present catalyst (impregnation method). The mixed solution is obtained by mixing a nickel nitrate aqueous solution, a lanthanum nitrate aqueous solution and a manganese nitrate aqueous solution in predetermined amounts so that the contents of nickel, lanthanum and manganese become predetermined values, and the carrier is gamma-alumina having a content of 96 wt% or more, a content of silica of about 3 wt%, and a BET specific surface area of about 180 to 200m²About/g of gamma-alumina carrier is dried at 80 deg.C for 16 hr, and sieved to obtain carrier with particle size of 200 μm or less, and the carrier is mixed with the mixed solutionThe carrier is added with a component of which the content of nickel, lanthanum and manganese is a predetermined value.

FIG. 5 shows the contents of nickel, lanthanum and manganese in samples D1 to D7, and the contents of C3 in sample D1 to D7 and C in sample X1 without manganese added for comparison₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), H₂The results of evaluation of the unit adsorption amount (before the initial evaluation and after the initial evaluation, and the comparative sample X1 is only before the initial evaluation) and the coking amount after the initial evaluation are summarized in a list. As sample C3, a sample prepared separately from the sample used for the evaluation shown in fig. 3 was used. The evaluation results of the ruthenium catalyst X1 were the same as those shown in fig. 3. The manganese contents of samples D1 to D7 were 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, and 2.0 wt%, in that order. The nickel content and the lanthanum content of samples D0 to D7 were fixed at 15 wt% and 10 wt%.

According to H shown in FIG. 5₂The results of the evaluation of the unit adsorption amount, before and after the initial evaluation, were H of sample D2₂The unit adsorption amount was the smallest, and the results of samples other than this were not significantly different. In particular, after the initial evaluation, all of the samples D1 and D3 to D7 except for the sample D2 showed H values higher than that of the sample D0 to which manganese was not added₂The unit adsorption capacity is large, which shows the effect of manganese addition.

C shown in FIG. 5₃H₈In the initial evaluation results of the conversion, in any case where the reaction temperature was 400 ℃, 500 ℃ and 600 ℃, C in samples D0 to D7₃H₈C with conversion rates all greater than that of comparative sample X1₃H₈The conversion rates and the catalytic activities of the samples D0-D7 were all high. At a reaction temperature of 400 ℃, the temperature between the samples D1-D7 is C₃H₈The conversion rate was different from that of sample D5 (manganese content: 1% by weight) containing C₃H₈The conversion rate is the greatest. C of samples D1, D4, D5, and D7 (manganese content: 0.05 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt%)₃H₈The conversion rate is higher than that shown in figures 3 and 5The value of sample C3 without manganese addition in (b) is considered to show the effect of manganese addition, although variations in the measured values are recognized.

In the results of evaluation of the coking amounts shown in fig. 5, the coking amounts of samples D1 to D7 (the content of manganese is 0.05 wt% to 2.0 wt%) were smaller than that of sample C3 to which no manganese was added, indicating the effect of manganese addition. In particular, the coking amount of sample D5 (manganese content of 1 wt%) was the smallest and was reduced to the same value as the coking amount (0.14%) of comparative sample (ruthenium catalyst) X1. When the manganese content is low, the coking amount tends to be slightly increased. When the manganese content is in the range of 0.1 to 2.0 wt%, the coking amount is 1.0 to 1.71 times the coking amount (0.14%) of the comparative sample (ruthenium catalyst) X1.

FIG. 6 shows the contents of nickel, lanthanum and manganese in samples E1 to E6, and C in samples E1 to E6 and comparative sample (ruthenium catalyst) X1₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), H₂The results of evaluation of the unit adsorption amount (before initial evaluation) and the coking amount after initial evaluation are summarized in a list of results. The evaluation results of the ruthenium catalyst X1 were the same as those shown in fig. 3. The manganese contents of samples E1 to E3 were 0.75 wt%, 1.5 wt%, and 3.0 wt%, respectively, and the total content of nickel and manganese and the content of lanthanum were fixed at 15 wt% and 10 wt%. The manganese contents of samples E4 to E6 were 0.5 wt%, 1.0 wt%, and 2.0 wt%, respectively, and the total content of nickel and manganese and the content of lanthanum were fixed at 10 wt% and 10 wt%.

In samples E1 and E4, 5% by weight of the loading of nickel was replaced by manganese, in samples E2 and E5, 10% by weight of the loading of nickel was replaced by manganese, and in samples E3 and E6, 20% by weight of the loading of nickel was replaced by manganese. Thus, the weight ratio of nickel to manganese loading (nickel: manganese) was 19: 1 in samples E1 and E4, 9: 1 in samples E2 and E5, and 4: 1 in samples E3 and E6.

H shown in FIG. 6₂In the evaluation results of the unit adsorption amount, H was observed when the content of nickel was increased₂The unit adsorption amount is also increasedIn this connection, the tendency was the same as the results of samples A1 to A6 and samples C1 to C4 to which manganese was not added shown in FIG. 1 and FIG. 3. In samples E1 to E6, since the content of nickel decreases as the amount of manganese added increases, the influence of the change in the content of nickel is large, and therefore, as a result of samples E1 to E6, the addition of manganese to H₂The effect per unit adsorption amount is not clear, but is similar to H shown in FIG. 5₂The evaluation results per unit adsorption amount are not contradictory.

C shown in FIG. 6₃H₈In the initial evaluation results of the conversion, in any case where the reaction temperature was 400 ℃, 500 ℃ and 600 ℃, C in samples E1 to E6₃H₈C with conversion rates all greater than that of comparative sample X1₃H₈The conversion rates and the catalytic activities of samples E1 to E6 were all high. At a reaction temperature of 400 ℃, the temperature between samples E1-E6 is C₃H₈There was a difference in conversion. C obtained from initial evaluation of samples C1 to C4 to which manganese was not added shown in FIG. 3₃H₈As a result of the evaluation of the conversion, C was observed until the content of nickel was increased to 15 wt% when the content of lanthanum was fixed at 10 wt%₃H₈In the relationship that the conversion rate also increased, however, among the manganese-added samples E1 to E3, the sample E2 having a nickel content of 13.5% by weight was more excellent than the samples E1 and E3 having nickel contents of 14.25% by weight and 12% by weight in comparison with the samples E1 and E3 having the same contents of nickel₃H₈Since the conversion rate was high, it can be said that the effect of manganese addition was increased in the order of the manganese content of 1.5 wt%, 3.0 wt%, and 0.75 wt%. On the other hand, the samples E4 to E6 containing manganese had a low content of nickel, unlike the samples C1 to C4 containing no manganese₃H₈C of sample with high conversion rate and high manganese content₃H₈The conversion rate becomes high. As can be seen from the above, manganese addition to C₃H₈The effect of conversion is evident.

When samples E1 and E2 were compared, the content of manganese increased by 0.75 wt% even though the content of nickel decreased by 0.75 wt%, and C at 400 ℃₃H₈The conversion also increased greatly from 83.63% to 91.56%. However, samples E2, E3 were comparedIn this case, the content of nickel was decreased by 1.5% by weight, and even if the content of manganese was increased by 1.5% by weight, C was observed at 400 ℃₃H₈The conversion also decreased from 91.56% to 84.04%. In this regard, the results of samples E4 to E6 and the C2 temperature at 400 ℃ of sample C2 which had the same nickel and lanthanum contents as sample E3 and had no manganese added were considered₃H₈When the conversion was 87.14%, it was considered that the manganese content of 3 wt% slightly exceeded the manganese content for C₃H₈The upper limit of a suitable range for conversion. Therefore, the upper limit of the suitable range is considered to be 2.5 to 3.0% by weight, more preferably 2.0 to 2.5% by weight. In addition, the lower limit of the suitable range is considered to be 0.05 wt%, more preferably 0.5 wt%.

In the results of evaluation of the coking amounts shown in fig. 6, the samples E1 to E3 had higher nickel contents than the samples E4 to E6, but the coking amounts were small, and the coking amounts of the samples E1 to E3 were all equal to or less than the coking amount (0.14%) of the comparative sample (ruthenium catalyst) X1.

With respect to C at 400 ℃₃H₈As a result of the evaluation of the conversion (initial evaluation) and the amount of coking, among the samples D0 to D7 shown in FIG. 5, C was contained in sample D5 (the content of manganese was 1% by weight)₃H₈The conversion rate was the largest and the coking amount was the smallest, and among samples E1 to E3 shown in FIG. 6, sample E2 (the manganese content was 1.5% by weight) contained C₃H₈The conversion is maximized and the coking amount is minimized, and therefore, the optimum value of the manganese content is estimated to be about 1.0 to 1.5 wt% (based on the amount of nickel, corresponding to 6.66 to 10 wt% of the amount of nickel).

When the results of the evaluation of the coking amounts shown in fig. 6 and the results of the evaluation of the coking amounts shown in fig. 5 are compared, it is understood that the catalytic activity higher than that of the comparative sample (ruthenium catalyst) X1 can be maintained and the coking amount can be suppressed to be equal to or less than that of the comparative sample X1 by reducing the content of nickel from 15% by weight by 0.75 to 3% by weight and instead by controlling the content of manganese to 0.75 to 3% by weight. It is thus assumed that: by replacing a part of nickel having a content within an appropriate range with manganese having a content within an appropriate range, the catalytic activity can be maintained higher than that of the comparative sample (ruthenium catalyst) X1, and the coking amount can be suppressed to be equal to or less than that of the comparative sample X1.

The evaluation results of the above samples a1 to a6, B0 to B7, C1 to C5, D1 to D7, and E1 to E6 are combined, and the appropriate ranges of the respective contents of nickel, lanthanum, and manganese are set as follows.

Nickel: 11 to 18 wt%, and more preferably 13 to 17 wt%.

Lanthanum: 8 to 12 wt%, and more preferably 10 to 12 wt%.

Manganese: 0.05 to 3 wt%, preferably 0.5 to 2.5 wt%, and more preferably 1 to 1.5 wt%.

The total content of nickel and manganese is preferably set to 11.05 to 21 wt%, more preferably 11.05 to 18 wt%, and still more preferably 13 to 17 wt%.

The total content of lanthanum and manganese is preferably set to 8.05 to 15 wt%, more preferably 10.05 to 15 wt%, and still more preferably 10.5 to 14.5 wt%.

The weight ratio of lanthanum to nickel (La/Ni) is preferably set to 50% to 120%, more preferably 75% to 100%.

The weight ratio of manganese to nickel (Mn/Ni) is preferably set to 0.33 to 20%, more preferably 3.33 to 20%, and still more preferably 6.66 to 15%.

[ investigation of second cocatalyst component ]

When manganese was selected as the second promoter component of the present catalyst, samples F1 to F9 were prepared in which calcium (Ca), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), molybdenum (Mo), and tungsten (W) were used as the second promoter component in addition to manganese, and C was performed₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), H₂Evaluation of the amount of coking per unit adsorption and after the initial evaluation. In samples F1 to F9, the respective contents of nickel, lanthanum, and the second promoter component were 13.5 wt%, 10 wt%, and 1.5 wt%, respectively, and were usedSample E2 was prepared in the same manner using nitrates of the metals of the second promoter component in place of the manganese nitrate of sample E2.

FIG. 7 shows metals used as the second promoter components of samples F1 to F9, nickel and lanthanum, the contents of the metals, and C in samples F1 to F9, sample E2, and comparative sample (ruthenium catalyst) X1₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), H₂The results of evaluation of the unit adsorption amount (before initial evaluation) and the coking amount after initial evaluation are summarized in a list of results. The evaluation results of sample E2 were the same as those shown in fig. 6, and the evaluation results of ruthenium catalyst X1 were the same as those shown in fig. 3.

H shown in FIG. 7₂In the evaluation results of the unit adsorption amount, H was calculated in the order of sample F1 (calcium), sample F5 (cobalt), sample F8 (molybdenum), and sample E2 (manganese)₂High specific adsorption, good results, other samples F2-F5, F7, and F9H₂The unit adsorption amount was lower than that of sample E2 (manganese).

C shown in FIG. 7₃H₈In the initial evaluation results of the conversion, 5 samples of sample F3 (chromium), sample F1 (calcium), sample F7 (zinc), sample F2 (vanadium), and sample F9 (tungsten) showed higher C than that of comparative sample (ruthenium catalyst) X1₃H₈Conversion, but all were lower than C for sample E2 (manganese)₃H₈And (4) conversion rate.

The results of the evaluation of the coking amounts shown in fig. 7 showed that the coking amounts of sample F9 (tungsten) and sample F4 (iron) were lower than those of sample E2 (manganese) and comparative sample (ruthenium catalyst) X1, and were good results.

However, by comprehensively judging the 3 evaluation results shown in FIG. 7, it is understood that manganese is most suitable as the second promoter component as described below.

C of sample F4 (iron) with low coke number 2₃H₈The conversion rate is low. C₃H₈The samples F3 (chromium), F1 (calcium), F7 (zinc) and F2 (vanadium) with relatively good conversions have higher coking amounts than the comparative sample (ruthenium catalyst) X1. H₂The unit adsorption amount is higher than that of sample E2 (manganese)Sample F1 (calcium), sample F6 (cobalt), sample F8 (molybdenum) C₃H₈The conversion was lower than that of comparative sample (ruthenium catalyst) X1, or the coking amount was lower than that of comparative sample (ruthenium catalyst) X1, or both of them were satisfied.

H2 Unit adsorption amount of sample F9 (tungsten) and C at 400 ℃₃H₈The conversion was lower than that of sample E2 (manganese), but the coking amount was the lowest and lower than that of sample E2 (manganese) and comparative sample (ruthenium catalyst) X1, and therefore among samples F1 to F9, tungsten was judged to be suitable next to manganese as the second promoter component.

Therefore, samples F10 and F11 (prepared by the same preparation method as that of sample F9) in which the respective contents of nickel, lanthanum and the second promoter component are the same as those of samples E1 and E2 and the second promoter component is tungsten were additionally prepared, and C at a reaction temperature of 450 ℃ was continuously evaluated for 96 hours (every 12 hours, 8 times) for samples E1 to E3, samples F9 to F11 and a sample for comparison (ruthenium catalyst) X1 together with the sample for comparison X1₃H₈And (4) conversion rate. The content of each of nickel, lanthanum, and tungsten in sample F10 was 14.25 wt%, 10 wt%, and 0.75 wt%, and the content of each of nickel, lanthanum, and tungsten in sample F11 was 12 wt%, 10 wt%, and 3 wt%. Samples E1 to E3 were prepared separately from the samples used for the evaluation shown in fig. 6, sample F9 was prepared separately from the samples used for the evaluation shown in fig. 7, and sample X1 for comparison was prepared separately from the samples used for the evaluation shown in fig. 3.

FIG. 8 shows C up to this 96 hour period₃H₈Evaluation results of conversion. According to the results shown in FIG. 8, C was measured for up to 96 hours at a reaction temperature of 450 ℃₃H₈Conversion, C in all 3 combinations of the contents of 3 components in samples E1 to E3 (manganese)₃H₈The conversion was 100%, whereas in samples F9 to F11 (tungsten), C was present₃H₈The conversion rates were not 100%, and C was contained in samples F10 and F9 in which the tungsten contents were 0.75 wt% and 1.5 wt%, respectively₃H₈C with higher conversion than comparative sample (ruthenium catalyst) X1₃H₈The conversion rate of the mixed solution is higher than that of the mixed solution,however, in sample F11 in which the tungsten content is 3 wt%, C is₃H₈Conversion ratio C of comparative sample (ruthenium catalyst) X1₃H₈The conversion rate is greatly reduced.

Thus, sample F9, in which the second promoter component was tungsten, exhibited slightly less coking than sample E2 (manganese), which was a good result, but was from C₃H₈From the viewpoint of conversion, samples E1 to E3 (manganese) were remarkably superior to samples F9 to F11 (tungsten).

[ investigation of Carrier Components ]

The carrier of the catalyst comprises gamma-alumina as a main component. The catalytic performance of the catalyst was evaluated in comparison with a comparative example in which the main component of the carrier was changed from γ -alumina to α -alumina, and the evaluation results will be described.

In this evaluation, 6 kinds of catalysts were prepared. 2 are a sample D2 of the present catalyst prepared separately from the sample used in the evaluation shown in fig. 5, and a sample E2 prepared separately from the sample used in the evaluation shown in fig. 6. The other 4 samples G1 to G4 were comparative examples. Samples G1 and G2 are comparative samples in which nickel, lanthanum, and manganese were supported on a carrier a containing α -alumina as a main component. Samples G3 and G4 are comparative samples in which nickel, lanthanum, and manganese were supported on a carrier B containing α -alumina as a main component. The respective contents of nickel, lanthanum, and manganese in samples G1 and G3 were 15 wt%, 10 wt%, and 0.1 wt%, in this order, as in sample D2. The respective contents of nickel, lanthanum, and manganese in samples G2 and G4 were 13.5 wt%, 10 wt%, and 1.5 wt%, in that order, as in sample E2.

The carrier A had an alpha-alumina content of about 99.5% by weight, contained about 0.5% by weight of silica, and had a BET specific surface area of about 6.1m²A/g of an alpha-alumina carrier. The carrier B was an alpha-alumina having a content of about 99.4% by weight, contained about 0.6% by weight of silica, and had a BET specific surface area of about 1.8m²A/g of an alpha-alumina carrier.

Samples G1 to G4 were prepared by exactly the same preparation method as samples D2 and E2, except that the carriers were different from samples D2 and E2. The carriers A and B were prepared by drying the samples G1 to G4 at 80 ℃ for 16 hours and sieving the dried samples to have a particle size of about 200 μm or less.

In this evaluation, C was carried out₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), H₂3 evaluations of the unit adsorption amount (before and after initial evaluation) and the coking amount (before and after initial evaluation).

FIG. 9 shows the carrier and the contents of nickel, lanthanum and manganese in samples D2, E2 and G1 to G4, and C in samples D2, E2 and G1 to G4₃H₈Conversion (initial evaluation at reaction temperature of 400 ℃, 500 ℃ and 600 ℃), H₂The results of evaluation of the unit adsorption amount (before and after the initial evaluation) and the coking amount (before and after the initial evaluation) are summarized in a table. The evaluation results of samples D2 and E2 were slightly different from the evaluation results shown in fig. 5 and 6, respectively.

C shown in FIG. 9₃H₈In the initial evaluation results of the conversion, the samples G1 to G4 in which the carrier main component was α -alumina had a very low initial catalytic activity, which was about 10% to 60% of those of the samples D2 and E2, regardless of the catalyst composition (content of 3 components) as compared with the samples D2 and E2 in which the carrier main component was γ -alumina.

H shown in FIG. 9₂As a result of the evaluation of the unit adsorption amount, H in samples G1 to G4 in which the carrier main component was α -alumina was compared with H in samples D2 and E2 in which the carrier main component was γ -alumina₂The unit adsorption amount is very small. In addition, in samples G1 to G4, regardless of the difference between the carriers A and B, when the manganese content is large (samples G2 and G4), H₂The unit adsorption amount was small, and the effect of manganese addition was not observed.

In the results of the evaluation of the coking amounts shown in fig. 9, no significant difference was observed between samples E2, G2, and G4 having a manganese content of 1.5 wt% in the coking amounts before and after the initial evaluation, and the coking amounts after the initial evaluation of samples G1 and G3(α -alumina carrier) were greater than that of sample D2(γ -alumina carrier) among samples D2, G1, and G3 having a manganese content of 0.1 wt%, and were particularly significant for the carrier a having a large BET value. Comparing the samples G1, G3(α -alumina support) with the samples E2, G2(α -alumina support), coking is suppressed when the content of manganese is large, indicating the effect of manganese addition.

As is clear from the evaluation results of the 3 items shown in fig. 9, the catalytic performance of the present catalyst cannot be sufficiently exhibited when the carrier is changed from a carrier containing γ -alumina as a main component to a carrier containing α -alumina as a main component.

[ study of Long-term stability ]

Next, C at a reaction temperature of 450 ℃ was evaluated using continuous (84 times per 12 hours) evaluation over 1008 hours₃H₈The results obtained from the conversion indicate the long-term stability of the catalyst. As the present catalyst, a sample E2 having contents of nickel, lanthanum, and manganese of 13.5 wt%, 10 wt%, and 1.5 wt% was prepared separately from the sample used in the evaluation shown in fig. 6, a sample C3(Ni — La catalyst) for comparison, in which manganese was not added to the present catalyst, was prepared separately from the sample used in the evaluation shown in fig. 3, and a sample X1 (ruthenium catalyst: ruthenium supported amount: 2 wt%, carrier: γ -alumina) for comparison was prepared separately from the sample used in the evaluation shown in fig. 3.

FIG. 10 shows C for 1008-hour continuous evaluation performed on samples E2, C3, X1₃H₈Results of conversion. The vertical axis of FIG. 10 is C₃H₈Conversion (%), and the horizontal axis represents the duration (hours) of the steam reforming reaction.

Sample E2 of the present catalyst maintained a higher C than the ruthenium catalyst X1₃H₈The conversion rate, at the time of 1000 hours, showed C as high as about 1.9 times, that is, 95.9% of that of the ruthenium catalyst X1₃H₈And (4) conversion rate. On the other hand, the comparative sample C3, to which manganese was not added, maintained C higher than that of the ruthenium catalyst X1 until 500 hours elapsed₃H₈Conversion, but C after the start of the evaluation₃H₈The conversion rate gradually decreased and became C lower than that of the ruthenium catalyst X1 after 504 hours had elapsed₃H₈And (4) conversion rate. Based on the above results canIt is known that sample E2 of the present catalyst can stably maintain a high catalytic activity for a long period of time by adding manganese as a second promoter.

This is because: the addition of manganese affects the metal dispersion on the catalyst surface, and as the amount of addition increases, the sintering resistance improves, and the time during which high metal dispersion can be maintained increases. In addition, these points were confirmed by Transmission Electron Microscope (TEM) images of the catalyst particles, element mapping evaluation, and the like. Here, although the TEM image and the element mapping evaluation result are not separately shown, fig. 10 shows a content reflecting the result.

Industrial applicability

The present invention is useful as a nickel-based steam reforming catalyst and is suitably used in a steam reforming system.