WO2019138536A1

WO2019138536A1 - Methanol steam reforming catalyst, methanol steam reforming device, and hydrogen production method

Info

Publication number: WO2019138536A1
Application number: PCT/JP2018/000630
Authority: WO
Inventors: 暁紅黎; 台藏伊藤; 杉山　英路
Original assignee: 公立大学法人北九州市立大学; 伊藤工機株式会社; 豊田通商株式会社
Priority date: 2018-01-12
Filing date: 2018-01-12
Publication date: 2019-07-18
Also published as: JP6936338B2; JPWO2019138536A1

Abstract

[Problem] The problem is to provide a methanol steam reforming catalyst having a further improved catalytic activity compared with a conventional methanol steam reforming catalyst in which silica is used as a support and copper particles are supported as a catalyst component. [Solution] In order to solve the problem, a methanol steam reforming catalyst for hydrogen production use is provided, in which silica is used as a support and copper particles are dispersed therein, wherein the ratio of the weight of silica to the weight of copper is 1:1 to 1:1.63. A methanol steam reforming catalyst as mentioned above is provided, wherein the ratio of the weight of silica to the weight of copper is more preferably 1:1 to 1:1.63.

Description

Methanol steam reforming catalyst, methanol steam reformer and hydrogen generation method

The present invention relates to a catalyst for producing hydrogen by methanol steam reforming.

Fossil fuels such as oil and natural gas have been pointed out various problems such as exhaustion and environmental destruction, and hydrogen is attracting attention as alternative energy with small environmental load. In particular, a significant increase in demand for fuels such as fuel cells is expected.

Production of hydrogen is carried out by decomposition reaction of hydrocarbons, and is produced by methods such as partial oxidation reaction, steam reforming, autothermal and the like. Among these, steam reforming, which is excellent in efficiency, has become the mainstream production method at present.

The catalyst plays a very important role in the production of hydrogen by steam reforming. The main items required for the catalyst include the improvement of the catalyst activity contributing to the reforming efficiency, the stability of the catalyst activity, and the suppression of the formation of harmful by-products.

The suppression of the production of harmful by-products means that not only hydrogen and carbon dioxide are produced by methanol steam reforming, but also the production of toxic carbon monoxide produced at the same time. As the amount of carbon monoxide replicated increases, it becomes necessary to increase the size and the capacity of the carbon monoxide removing means provided with the steam reforming apparatus, resulting in an increase in hydrogen production cost.

The invention disclosed in Patent Document 1 is a catalyst that suppresses the formation of carbon monoxide, which is a by-product in particular, and is made by supporting copper particles having a content of 20 to 60% by weight on a silica carrier. It is a steam reforming catalyst. In Patent Document 1, methanol steam reforming is performed using copper nitrate, tetramethoxysilane, water and a catalyst in which the content of raw material copper particles is 40% by weight, and as a result, by-products are The excellent production inhibitory effect that the selectivity of carbon monoxide was 0.06% was shown.

JP, 2008-043884, A

As described above, although there are excellent inventions to suppress the formation of harmful by-product carbon monoxide, there is still room for improvement in catalyst activity. Therefore, it is an object of the present invention to further improve the catalytic activity.

In order to solve the above-mentioned problems, the present invention provides the following methanol steam reforming catalyst and the like. That is, it is a methanol steam reforming catalyst for hydrogen generation in which copper particles are dispersedly disposed with silica as a carrier and the weight ratio of silica to copper is between 1: 1 and 1: 1.63. Provide quality catalyst.

In addition, it is a methanol steam reforming catalyst for hydrogen generation in which copper particles are dispersedly disposed with silica as a support, and the weight ratio of silica to copper is between 1: 1.08 and 1: 1.50. Provided is a methanol steam reforming catalyst.

Further, in any of the above methanol steam reforming catalysts, copper provides a methanol steam reforming catalyst which is copper nanoparticles.

In addition, any one of the above methanol steam reforming catalysts, which is a porous body consisting of sub-nanopores to nanopores having a pore diameter of 0.5 nm to 2 nm of a main peak according to SF-Plot analysis. Provide a reforming catalyst.

Further, the present invention provides a methanol steam reforming catalyst according to any one of the above, further comprising cerium oxide and / or aluminum oxide as a carrier.

Further, in any of the above methanol steam reforming catalysts, copper provides a methanol steam reforming catalyst containing a copper nanoparticle precursor.

Also, a hydrogen having a temperature control unit that sets the reaction temperature of methanol and steam to 250 ° C. plus or minus 10%, and a methanol steam reaction unit equipped with the methanol steam reforming catalyst of any of the above methanol steam reforming catalysts. A methanol steam reformer for production is provided.

Further, the present invention provides a hydrogen generation method for generating hydrogen by reacting methanol and steam using any of the above methanol steam reforming catalysts with the reaction temperature of methanol and steam set to 250 ° C. plus or minus 10%.

According to the present invention having the above constitution, there is provided a methanol steam reforming catalyst in which the catalyst activity is further improved with respect to a methanol steam reforming catalyst having a conventional silica as a carrier and supporting copper particles as a catalyst component. be able to.

Figure showing the reaction results of methanol steam reforming with a catalyst in which a silica support supports copper particles Figure showing the relationship between the weight ratio of copper and the space-time yield for the reaction results in Figure 1 Figure showing the reaction results of methanol steam reforming with a catalyst in which a silica support supports copper particles Figure showing reaction results of methanol steam reforming with catalyst supporting silica particles and cerium oxide as a carrier and supporting copper particles Diagram showing the reaction results of methanol steam reforming with a catalyst supporting silica particles and aluminum oxide as a carrier and supporting copper particles

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to these embodiments at all, and can be implemented in various modes without departing from the scope of the invention.
Embodiment

The methanol steam reforming catalyst of the present embodiment is a methanol steam reforming catalyst for producing hydrogen, in which copper particles as a catalyst component are dispersedly disposed with silica (SiO ₂ ) as a carrier. And, it is characterized in that the weight ratio of silica to copper is between 1: 1 and 1: 1.63. The thus-configured methanol steam reforming catalyst can provide superior catalytic activity as compared to a methanol steam reforming catalyst in which conventional silica is used as a carrier and copper particles are supported as a catalyst component.

In order to disperse and arrange copper particles in silica as a carrier, preparation by a sol-gel method is preferable. For example, a copper particle is added to a mixed solution of silicon alkoxide such as tetramethoxysilane or tetraethoxysilane and water, and stirred to prepare a sol, and the gel left to stand for a predetermined time and dried is heat treated at 300 ° C. for 3 hours It is possible to obtain silica in which particles or copper oxide particles are dispersed.

In addition, reduction treatment may be performed after heat treatment, reduction treatment may be performed when performing methanol steam reforming, or methanol steam reforming may be performed in a reducing gas atmosphere such as argon. This is because suppressing the oxidation of the copper particles to bring them into the reduction state contributes to the improvement of the catalytic activity.

The copper particles to be mixed are preferably nano copper particles having a particle diameter of about 1 nm to 100 nm. By making the particle size of the copper particles nano-sized, the specific surface area is large, which contributes to good catalytic activity. As a result of measuring the surface characteristics of the prepared “55 wt% Cu / 45 wt% SiO ₂ ” (SiO ₂ : Cu = 1: 1.22) (as measured by Microtrack Bell Inc. nitrogen adsorption), BET specific surface area: 132 m ² / g, pore volume: 0.1520 cm ³ / g, the pore diameter of the first peak by SF-Plot analysis was 0.66 nm, and the pore diameter of the second peak was 0.97 nm . When the same sample is analyzed by BJH-Plot, the peak of the pore appears at 3.18 nm, but BJH-Plot analysis is suitable for mesopore analysis, and the pore analysis of the catalyst according to the present invention It is not considered suitable for

Here, by appropriately setting the mixing ratio of the silicon alkoxide and the copper particles, it is possible to make the weight ratio of the silica obtained after the heat treatment and the copper particles carried thereon be a desired weight ratio.

Thus, the silica prepared by the sol-gel method constitutes a three-dimensional network structure, and the copper particles are uniformly incorporated into the network structure to be dispersed and supported. Further, by supporting the copper particles on the silica having a network structure, aggregation of the copper particles can be prevented, and good catalytic activity can be obtained.

Further, in the above-described preparation method, a copper particle precursor may be mixed with the liquid mixture of silicon alkoxide and water instead of the copper particles. As a copper particle precursor, a salt of copper dissolved in water or an organic copper compound that undergoes a hydrolysis reaction can be used. Specifically, copper chloride, copper sulfate, copper nitrate, copper carbonate, copper acetate, copper ethoxide and the like can be mentioned.

In the preparation method described above, not only silicon alkoxide but also cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), aluminum nitride (AlN), silicon carbide (SiC), beryllium oxide An inorganic crystal component that improves mechanical properties, heat transfer properties, heat resistance and the like as a carrier such as (BeO) may be added, or a metal such as aluminum may be added. The addition amount is preferably 5 to 50 wt% with respect to the whole. If the amount is less than that, the targeted improvement in mechanical properties, heat transfer characteristics, heat resistance, etc. can not be obtained, and if the amount is more than this, the catalyst performance is degraded. Also in this case, the weight ratio of silica to copper is made to be between 1: 1 and 1: 1.63.

The above-described methanol steam reforming catalyst according to the present invention has a methanol steam reaction unit provided as a catalyst according to the present invention in a known catalytic reaction device, and temperature control to set the reaction temperature of methanol and steam to 250 ° C. plus or minus 10%. By being configured to include a part, the present invention can also be embodied as a methanol steam reformer for hydrogen generation.
<Catalytic activity evaluation>

The following shows the results of methanol steam reforming using the methanol steam reforming catalyst of the present embodiment.

The catalyst used was prepared by silicon alkoxide and copper particles, and neither a copper particle precursor, cerium oxide nor aluminum oxide was added. In addition, the weight ratio of silica to copper was changed to several to evaluate catalyst activity.

The methanol reforming conditions were such that a mixed gas of methanol and steam was circulated to the reactor at a space velocity SV of 8800 h ^-1 and a reaction temperature of 250 ° C. (SV = flow rate Q (m ³ / h) / catalyst Volume (m ³ )). FIG. 1 shows the reaction result of methanol steam reforming carried out under this condition. The weight ratio of silica to copper is changed, and the space-time yields of hydrogen, carbon monoxide, carbon dioxide and methane produced by the respective catalysts are measured to evaluate the catalyst activity. The graph shows hydrogen, carbon monoxide, carbon dioxide, and methane from the left as shown in the figure, but what is not recognized in the graph is that the amount of carbon monoxide and methane produced is small or extremely small. It is for.

As shown in the figure, the space-time yield of hydrogen in the catalyst of “50 wt% Cu / 50 wt% SiO ₂ ” (Sio ₂ : Cu = 1: 1) is 300, “40 wt% Cu / 60 wt% SiO ₂ ” It can be seen that it is about 10% higher than the space-time yield 270 of hydrogen in the catalyst of Sio ₂ : Cu = 1: 0.67). Furthermore, the space-time yield of hydrogen in the catalyst of “55 wt% Cu / 45 wt% SiO ₂ ” (Sio ₂ : Cu = 1: 1.22) is 420, and hydrogen in the catalyst “40 wt% Cu / 60 wt% SiO ₂ ” Relative to the space-time yield 270 of about 50%. Moreover, the space-time yield of hydrogen in the catalyst of “60 wt% Cu / 40 wt% SiO ₂ ” (Sio ₂ : Cu = 1: 1.5) is 340, and the hydrogen in “40 wt% Cu / 60 wt% SiO ₂ ” catalyst It is understood that the space-time yield 270 of the

Thus, when the weight ratio of silica to copper was 1: 1, an improvement in space-time yield of 10% was observed for a catalyst containing copper in a 40 percent weight ratio. And, as the weight ratio of silica to copper exceeds 1: 1, the space-time yield is further improved. Further, it was also shown that the generation of carbon monoxide is small and the selectivity is excellent.

FIG. 2 estimates the relationship between the weight ratio of copper and the space-time yield for the reaction result of FIG. As illustrated, the weight ratio of silica to copper is between 1: 1 (50 wt% Cu / 50 wt% SiO ₂ ) to 1: 1.63 (62 wt% Cu / 38 wt% SiO ₂ ) ([1] in the figure) Of the catalyst of “40 wt% Cu / 60 wt% SiO ₂ ” shown in the prior art, the catalyst activity is about 10% or more.

In particular the weight ratio of silica and copper from 1: 1.08 (52wt% Cu / 48wt% SiO 2) 1: the range between (in FIG. [2] of 1.50 (60wt% Cu / 40wt% SiO 2) ) with, it can be said that the performance of the catalyst which has been shown in the prior art "40wt% Cu / 60wt% SiO _2" shows the about 20% or more catalytic activity. In catalytic chemistry, a performance improvement of 10% or more is a remarkable improvement, and in particular, a methanol steam reforming catalyst with a weight ratio of silica to copper of 1: 1.08 to 1: 1.50 has a remarkable effect. It can be said that

FIG. 3 is a view showing the reaction result of methanol steam reforming using a catalyst of “55 wt% Cu / 45 wt% SiO ₂ ”, and the flow time (horizontal axis), space-time yield (vertical axis) and methanol conversion The relationship with the rate (second axis) is shown. The reaction conditions were such that a space velocity SV: 5000 h ^-1 and a reaction temperature of 250 ° C. were passed. As shown, it can be seen that high space-time yield and methanol conversion are maintained from the beginning of circulation to 400 hours. That is, it was shown that such a catalyst has high catalytic activity and is also excellent in stability of the catalytic activity.

FIG. 4 is a view showing the reaction result of methanol steam reforming for a case containing cerium oxide (CeO ₂ ) as a support. As shown, the weight ratio of silica to copper in the tested catalysts was all in the range of 1: 1 to 1: 1.63, and the reaction with cerium oxide was generally good.

FIG. 5 is a view showing the reaction result of methanol steam reforming for a case including aluminum oxide (Al ₂ O ₃ ) as a support. As shown, the weight ratio of silica to copper in each of the tested catalysts was between 1: 1 and 1: 1.63, and the reaction with aluminum oxide was generally good.

As shown in FIG. 3 and FIG. 4, the methanol steam reforming catalyst in which the copper particles were dispersedly disposed with only silica as the carrier was the most excellent in catalytic activity.

In the SiO ₂ network structure, Cu nanoparticles have an electrostatic interaction with O (oxygen) binding to Si, but if the Cu / SiO ₂ weight ratio is less than 1, Cu and The electrostatic interaction of O is so strong that reduction to free Cu is difficult and the catalytic activity is reduced. On the other hand, when the weight ratio of Cu / SiO ₂ is more than 1, the reduction of the electrostatic interaction between Cu and O is reduced, which facilitates the reduction to free Cu, and the catalytic activity is considered to be remarkably improved. .

Further, in the present invention, by setting the weight ratio of Cu / SiO ₂ to 1 or more, Cu fine particles are not only prevented from aggregation or sintering and stably immobilized, but also in the redox reversible reaction of Cu, in the SiO ₂ matrix. From the viewpoint of the electrostatic interaction between O and Cu, it is believed that Cu can maintain a good reduction state, and as a result, high catalytic activity is maintained.

When the weight ratio of Cu / SiO ₂ exceeds 1.63, the electrostatic interaction between Cu and O becomes too weak, the solidifying power of Cu nanoparticles by the SiO ₂ matrix is weakened, and Cu aggregation, sintering As a result, the catalyst performance is considered to be reduced.

In addition, the composite of Cu nanoparticles and silica prepared by the sol-gel method in the weight ratio of the present invention has a pore diameter of the first peak of 0.66 nm by SF-Plot analysis and a pore diameter of the second peak of 0. Since the porous body has a pore volume of 0.5 to 3.0 cm ³ / g consisting of subnanopores to nanopores of 97 nm and a BET specific surface area of 50 to 300 m ² / g, It is considered that high catalytic activity can be obtained because it facilitates mass transfer of the reactant (methanol, water) and the product (carbon dioxide, hydrogen) as well as stably immobilizing in the structure. .
<Effect>

Provided is a methanol steam reforming catalyst in which the catalytic activity is further improved with respect to a methanol steam reforming catalyst supporting a conventional silica as a catalyst component and supporting copper particles as a catalyst component by the methanol steam reforming catalyst of the present embodiment. be able to.

Claims

It is a methanol steam reforming catalyst for hydrogen generation, in which copper particles are dispersedly disposed with silica as a carrier,
A methanol steam reforming catalyst wherein the weight ratio of silica to copper is between 1: 1 and 1: 1.63.
It is a methanol steam reforming catalyst for hydrogen generation, in which copper particles are dispersedly disposed with silica as a carrier,
A methanol steam reforming catalyst wherein the weight ratio of silica to copper is between 1: 1.08 and 1: 1.50.
The methanol steam reforming catalyst according to claim 1 or 2, wherein the copper is copper nanoparticles.
The methanol steam according to any one of claims 1 or 2, characterized in that the pore diameter of the main peak according to SF-Plot analysis is a porous body consisting of subnanopores to nanopores having a diameter of 0.5 nm to 2 nm. Reforming catalyst.
The methanol steam reforming catalyst according to any one of claims 1 to 4, further comprising cerium oxide and / or aluminum oxide as a support.
The methanol steam reforming catalyst according to any one of claims 1 to 5, wherein the copper contains a copper nanoparticle precursor.
Temperature control unit that sets the reaction temperature of methanol and steam to 250 ° C plus or minus 10%,
A methanol steam reforming apparatus for hydrogen generation, comprising: a methanol steam reaction unit provided with the methanol steam reforming catalyst according to any one of claims 1 to 6.
Assuming that the reaction temperature of methanol and steam is 250 ° C plus or minus 10%,
A method for producing hydrogen, which produces hydrogen by reacting methanol and steam using the methanol steam reforming catalyst according to any one of claims 1 to 6.