JP2007244996A - Catalyst for converting/supplying fuel, apparatus for converting/supplying fuel, and method for converting/supplying fuel by using the apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for converting/supplying fuel, which can be designed to be more compact than the conventional one and can effectively convert mixed fuel containing an oxygen-containing compound such as alcohol from a low temperature range of around 200°C and to provide an apparatus for converting/supplying fuel and a method for converting/supplying fuel using the apparatus for converting/supplying fuel. <P>SOLUTION: The catalyst for converting/supplying fuel contains Pt and a compound containing Ce, Ti, Zr, Nb, an alkali metal, an alkaline-earth metal or the like and is used for converting mixed fuel composed of hydrocarbon-based fuel and oxygen-containing compound fuel, or contains Cu and an oxide containing Al, Si, Zn, Mg or the like and is used for converting the mixed fuel. The apparatus for converting/supplying fuel is provided with the catalyst for converting/supplying fuel. When the mixed fuel composed of hydrocarbon-based fuel and oxygen-containing compound fuel is brought into contact with the catalyst for converting/supplying fuel, temperature control using the waste heat from an internal-combustion engine is performed, the mixed fuel is converted, and the converted fuel is supplied to the internal-combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel conversion / supply catalyst, a fuel conversion / supply device, and a fuel conversion / supply method using the same, and more specifically, when a mixed fuel containing an oxygen-containing compound such as ethanol is used. The present invention relates to a fuel conversion / supply catalyst, a fuel conversion / supply device, and a fuel conversion / supply method using the same, which can supply fuel with appropriate characteristics according to the operating conditions of the internal combustion engine.

In consideration of the global environment, reduction of carbon dioxide (CO2) emissions has been screamed, and various attempts have been made for the purpose of improving the fuel efficiency of automobile internal combustion engines.
For example, various measures such as high pressure injection technology for gasoline lean burn engines, direct injection engines, and diesel engines, and addition of an octane number improver for fuel are being implemented.
In addition to conventional gasoline and light oil as fuel approaches, hydrogen, alcohol (methanol, ethanol, etc.), ether (dimethyl ether, methyl tertiary butyl ether, etc.), biodiesel, synthetic fuel (GTL), etc. Alternative fuels have also been considered.

Here, ethanol is reproducible because it can be produced from bio origin, and has recently attracted attention as a carbon neutral fuel that does not increase CO2 in the atmosphere.
In addition, since alcohols contain oxygen atoms in their molecules, mixing with gasoline is expected to improve the octane number and contribute to improving fuel combustibility.
For this reason, in some countries such as Brazil and the United States, a gas hole, which is a fuel in which a certain amount of ethanol is mixed with gasoline, is already used as a fuel for an internal combustion engine.

  However, alcohol is simply inferior to gasoline and has a lower calorific value, so the output will be reduced by the amount of mixing, which may adversely affect fuel consumption. It's hard to say that it leads to savings.

From such a background, for the purpose of optimizing various conditions when supplying a mixed fuel of gasoline, light oil, etc. and alcohol to the internal combustion engine, a method of supplying the mixed fuel to the internal combustion engine, an injection method, etc. Various techniques have been proposed (see, for example, Patent Documents 1 and 2).
Japanese Examined Patent Publication No. 60-47469 JP-A-6-10787

  In Patent Document 1, an alcohol-mixed gasoline fuel is heated to a temperature higher than the reforming temperature of alcohol to obtain reformed gas, and at the same time, gasoline is gasified, and then the gasified gasoline fuel is cooled and condensed to be separated from the reformed gas. However, they are supplied to the engine by a separate system.

  In this case, the alcohol seems to be effective in the case of methanol which is relatively easy to reform, but in the case of ethanol which requires a higher reforming temperature, it was difficult to convert it into a reformed gas. In addition, the main idea is to obtain hydrogen from alcohol by reforming. To that end, water must be added. For alcohol that is difficult to reform, such as ethanol, a predetermined reformed gas can be obtained. Has become even more difficult. Further, the relationship between the operating conditions of the internal combustion engine and the supply of the reformed gas is not taken into consideration, and it has been unclear whether the obtained reformed gas can contribute to improving the efficiency of the internal combustion engine.

  Patent Document 2 proposes a compact double fuel injection valve for effectively supplying and injecting alcohol-mixed light oil, for example.

In this case as well, if a fuel component advantageous for diesel engine combustion is obtained from the mixed alcohol fuel, it is considered that the conventional injection device can also improve the combustion efficiency.
However, Patent Document 2 focuses on the fuel injection valve, and does not consider the characteristics of the fuel, that is, the alcohol species to be mixed.

As described above, the conventional technology relating to the supply of oxygen-containing compounds and alcohol-mixed fuels to the internal combustion engine has been focused on methanol that is relatively easily reformed as alcohol. In addition, the relationship with operating conditions was not fully considered, and effective use was not made.
That is, recently, a fuel conversion / supply catalyst that works efficiently from low temperatures has not been proposed for a mixed fuel that uses bio-derived ethanol, which has attracted attention as a renewable energy fuel, as part of the fuel. There was no effective use.
In addition, when converting fuel supplied to an internal combustion engine such as an automobile, downsizing of the catalyst used is a very important factor.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to design a mixed fuel containing an oxygen-containing compound such as alcohol that can be designed more compactly than conventional products. An object of the present invention is to provide a fuel conversion / supply catalyst, a fuel conversion / supply device, and a fuel conversion / supply method using the same, which can be effectively converted even from a low temperature range of about 200 ° C.

  As a result of intensive studies to solve the above problems, the present inventor has developed a catalyst in which platinum is combined with cerium, titanium, zirconia, niobium, alkali metal, alkaline earth metal, etc., copper, aluminum, silicon, The present inventors have found that the above problems can be solved by using a catalyst combined with zinc, magnesium, etc., and have completed the present invention.

That is, the fuel conversion / supply catalyst of the present invention is a catalyst used in an apparatus for supplying a fuel component to an internal combustion engine,
Containing platinum and a compound containing at least one element selected from the group consisting of cerium, titanium, zirconia, niobium, alkali metals and alkaline earth metals,
It is characterized in that at least a part of a mixed fuel composed of a hydrocarbon-based fuel and an oxygen-containing compound fuel is converted into another fuel component.

Further, another fuel conversion / supply catalyst of the present invention is a catalyst used in an apparatus for supplying a fuel component to an internal combustion engine,
Copper and an oxide containing at least one element selected from the group consisting of aluminum, silicon, zinc and magnesium,
It is characterized in that at least a part of a mixed fuel composed of a hydrocarbon-based fuel and an oxygen-containing compound fuel is converted into another fuel component.

  Furthermore, a fuel conversion / supply device according to the present invention is characterized by comprising the fuel conversion / supply catalyst.

Furthermore, the fuel conversion / supply method of the present invention, when converting and supplying fuel using the fuel conversion / supply device,
When contacting a mixed fuel composed of a hydrocarbon-based fuel and an oxygen-containing compound fuel with a fuel conversion / supply catalyst, temperature control of the catalyst or its vicinity is performed using waste heat from an internal combustion engine,
At least a part of the mixed fuel is converted into another fuel component and supplied to the internal combustion engine.

  According to the present invention, a catalyst in which platinum is combined with cerium, titanium, zirconia, niobium, alkali metal, alkaline earth metal, or the like, or a catalyst in which copper is combined with aluminum, silicon, zinc, magnesium, or the like is used. Therefore, it is possible to design more compact than conventional products, and a fuel conversion / supply catalyst that can effectively convert a mixed fuel containing an oxygen-containing compound such as alcohol from a low temperature range of about 200 ° C., fuel conversion / supply An apparatus and a fuel conversion / supply method using the same can be provided.

  Hereinafter, the fuel conversion / supply catalyst of the present invention will be described in detail. In the present specification, “%” indicates a mass percentage unless otherwise specified.

As described above, the first fuel conversion / supply catalyst of the present invention converts at least a part of a mixed fuel composed of a hydrocarbon-based fuel and an oxygen-containing compound fuel into another fuel component, and supplies it to an internal combustion engine. It is a catalyst used for the apparatus to supply.
In addition, the structure includes platinum (Pt), cerium (Ce), titanium (Ti), zirconia (Zr), niobium (Nb), alkali metal or alkaline earth metal, and any combination thereof. And a compound containing.

  Further, the second fuel conversion / supply catalyst of the present invention has the same application as the first catalyst, but the constitution thereof is copper (Cu), aluminum (Al), silicon (Si), zinc. (Zn) or magnesium (Mg), and oxides including those according to any combination thereof.

  With such a configuration, the first and second fuel conversion / supply catalysts can easily burn oxygen-containing compounds such as ethanol in a mixed fuel such as hydrogen, ethylene, and CO from a low temperature condition of about 200 ° C. even in a small amount. It can be converted into fuel.

  Here, among the mixed fuels that can be converted by the fuel conversion / supply catalyst of the present invention, as the hydrocarbon fuel, for example, gasoline, light oil, biodiesel, synthetic light oil (GTL), or the like can be used. As the oxygen-containing compound fuel, for example, methanol, ethanol, MTBE (methyl tertiary butyl ether), ETBE (ethyl tertiary butyl ether), or the like can be used.

Next, the fuel conversion / supply device of the present invention will be described in detail.
The fuel conversion / supply device of the present invention comprises the above-described fuel conversion / supply catalyst.

Here, FIG. 1 shows an outline of a combustion system to which the fuel conversion / supply device is applied.
As shown in FIG. 1, this combustion system has a fuel conversion / supply device, which is composed of a fuel tank 1 capable of supplying a mixed fuel and heat exchangers 2, 2 ′.
The fuel supply from the fuel tank 1 can be performed by two systems of the A path and the B path. From the A route, the mixed fuel can be supplied as it is to the intake side of the gasoline internal combustion engine. From the route B, the mixed fuel can be supplied to the intake side of the internal combustion engine after flowing through the heat exchanger 2 ′ installed on the exhaust system side.
Further, a fuel conversion / supply catalyst 3 is installed in the heat exchanger 2 ′, and fuel can be converted by utilizing the heat of the exhaust.

In this system, for example, when the internal combustion engine is started, the mixed fuel is directly injected and supplied from the fuel supply path A and burned. When the exhaust temperature of the internal combustion engine rises, the system is switched to the fuel supply path B via the heat exchanger. You can drive. As the mixed fuel, for example, gasoline containing 10% ethanol (regular gasoline) can be used.
At this time, when the heat is insufficient, it is possible to heat as necessary by incorporating a heater in the heat exchanger.
Further, by sending a part of the exhaust gas (EGR gas) to the catalyst 3 in the heat exchanger 2 ', the pressure and oxygen can be controlled. In this case, the efficiency of the conversion reaction can be increased. The heat exchanger 2 ′ is preferably installed at a position where the heat from the exhaust gas of the internal combustion engine can be utilized.
Waste heat is given to the catalyst 3 via the heat exchanger 2 ', but the heat exchanger 2' itself can be installed in the exhaust pipe or around the exhaust pipe.

In particular, the catalyst 3 is effective when the exhaust temperature is low during low speed operation with a low load on the internal combustion engine, such as a hydrogen generation reaction from the contained alcohol, an ethylene generation reaction by decomposition of the alcohol, a CO generation reaction, etc. Various reactions such as hydrogen production reaction from some gasoline and ethylene production reaction by decomposition reaction contribute to the expansion of the lean burn area of the internal combustion engine, which can contribute to the improvement of fuel consumption.
Since the hydrogen generation reaction and the ethylene generation reaction are endothermic reactions, the heat of the exhaust gas can be recovered as a result, and the fuel efficiency improvement effect can be increased.
The fuel component that has passed through the heat exchanger 2 can be directly injected into the internal combustion engine, but after the gas and liquid are separated into a gas component and a liquid component by heat exchange and cooling in the heat exchanger 2 ′. Both fuel components can also be injected. At this time, the fuel injectors for gas and liquid may be used in combination.

Next, the fuel conversion / supply method of the present invention will be described in detail.
In the fuel conversion / supply method of the present invention, when the fuel is converted / supplied using the fuel conversion / supply device described above, a mixed fuel composed of a hydrocarbon-based fuel and an oxygen-containing compound fuel is used as a fuel conversion / supply catalyst. When contacting, temperature control of the catalyst or its vicinity is performed using waste heat from the internal combustion engine, and at least a part of the mixed fuel is converted into other fuel components and supplied to the internal combustion engine.

Thus, by performing the temperature control of the catalyst using the waste heat from the internal combustion engine, the heat recovery becomes possible, so the fuel efficiency improvement effect is increased.
The conversion efficiency of the mixed fuel depends on the type and content of the oxygenated compounds contained, but in the case of gasoline containing about 10% ethanol, about 60-80% of the contained ethanol is used as another fuel component. It is expected that it can be converted and supplied.

Here, it is preferable that the temperature control by waste heat can heat a catalyst or its vicinity to about 200-400 degreeC.
The mixing ratio of the hydrocarbon-based fuel and the oxygen-containing compound fuel constituting the mixed fuel is assumed to be in the range of 90:10 to 15:85, for example, as hydrocarbon-based fuel: oxygen-containing compound fuel (ethanol fuel). The

Further, it is preferable that at least a part of the exhaust gas from the internal combustion engine is mixed with the mixed fuel and supplied to the catalyst.
For example, components such as moisture, nitrogen oxides, carbon monoxide (CO), and hydrocarbons (HC) in the exhaust gas can be used, which contributes to the recovery of heat and contributes to the cleanliness of the exhaust.

At this time, the oxygen concentration of the mixed gas (mixed fuel + exhaust gas) obtained by the mixing process can be controlled. Thereby, fuel conversion reaction can be performed effectively.
Specifically, oxygen is preferably contained in the mixed gas at a ratio of about 0.1 to 3.0%.

Furthermore, when the mixed fuel is brought into contact with the fuel conversion / supply catalyst, it is preferable to control the pressure in the reaction field of the catalyst. Thereby, the controllability of the conversion reaction is enhanced.
Specifically, it is good to control to about 0.3 to 10 Pa.

  Furthermore, from the viewpoint of improving the efficiency of the conversion reaction, it is preferable to use ethanol fuel as the oxygen-containing compound fuel.

The fuel conversion / supply catalyst can be applied to, for example, nickel (Ni) metal foam having pores of 30 ppi, so that light-off characteristics and responsiveness can be improved, and the catalyst utilization rate can be improved.
In particular, it is preferably applied to a metal carrier having three-dimensional continuous pores. For example, a metal foam carrier such as a nickel alloy, that is, a monolith carrier having three-dimensional continuous pores and a porosity of 80% or more can be used. In this case, a sufficient conversion function can be obtained with a small amount of catalyst, and light-off characteristics and responsiveness can be improved.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the technical scope of the present invention is not limited to the following examples.

(Example 1) Preparation of 1% Pt-0.3% Cs / CeO2-Nb2O5 (Ce: Nb = 50: 50 molar ratio) A predetermined amount of 10% ceria sol solution and 10% niobium sol solution were mixed and heated on a hot plate The water was removed while stirring at rt and dried at 150 ° C. overnight. Next, firing was performed at 600 ° C. for 2 hours in the air in an electric furnace.
On the other hand, a predetermined amount of a dinitrodiammine platinum aqueous solution and a cesium nitrate aqueous solution were mixed, and a predetermined amount of platinum and cesium were supported on the CeO2-Nb2O5 powder obtained by the impregnation method. Similarly, after drying at 150 ° C. overnight, firing was performed at 500 ° C. for 2 hours in the atmosphere using an electric furnace, and 1% Pt−0.3% Cs / CeO 2 —Nb 2 O 5 (Ce: Nb = 50: 50 mol) Ratio) of catalyst powder.

  Next, in order to convert the catalyst powder into a monolith catalyst, a slurry was prepared from the catalyst powder. Add 3% of the above catalyst powder, water, and silica sol as a binder to a porcelain pot mill, crush and shake for about 1 hour, take out, and add and adjust moisture while stirring with a stirrer Thus, a catalyst slurry having an appropriate viscosity was obtained.

  A nickel metal foam having an average three-dimensional pore density of 30 ppi was prepared. The metal foam was immersed in the catalyst slurry solution, excess slurry was removed, and about 80 g of catalyst powder (including silica binder) was applied per unit volume (1 L) of metal foam. After drying at 150 ° C. and firing at 500 ° C., the catalyst was fixed on the metal foam skeleton to obtain a foam catalyst (1) according to Example 1.

(Examples 2 to 5)
The metal foam catalyst was prepared through the catalyst powder and catalyst slurry which become Example 2-5 with the same procedure and method as Example 1. Regarding the raw materials in each catalyst preparation, 10% sol was used for both titania and zirconia, and nitrate was used for calcium.
Example 2 is a 1% Pt / TiO ₂ (rutile type) catalyst, Example 3 is 1% Pt / CeO ₂ —ZrO ₂ (Ce: Zr = 80: 20 molar ratio), and Example 4 is 1% Pt / Nb. ₂ O ₅ , Example 5 showed 1% Pt-0.2% Ca / CeO ₂ —Nb ₂ O ₅ (Ce: Nb = 50: 50 molar ratio).

(Examples 6 to 8) Preparation of 10% Cu / Al2O3 catalyst An aqueous copper nitrate solution was prepared, γ-alumina powder was charged into the solution, and a 10% aqueous ammonia solution was added dropwise while stirring with a stirrer. Was precipitated. Excess water was removed by filtration, and the resulting cake was put in a dryer and dried at about 100 ° C. for 2 days, and then calcined in the electric furnace at 500 ° C. for 2 hours to obtain a catalyst powder. Thereafter, a catalyst slurry was prepared in the same manner as in Example 1 to obtain a metal foam catalyst (6). The catalyst slurry was applied to the metal foam in exactly the same manner to obtain a metal foam type catalyst (7), a 20% Cu / SiO 2 catalyst and a metal foam catalyst (8) 20% Cu-5% Zn / Al 2 O 3.

(Performance evaluation)
For the fuel conversion / supply metal foam-supported catalysts obtained in Examples 1 to 7, the ethanol conversion and hydrogen generation characteristics at the catalyst inlet temperature of 100 to 500 ° C. were measured as follows.
The catalyst size was 6.0 cc, and as a pretreatment, 10% H ₂ / N ₂ balance gas was supplied at a flow rate of 5 L / minute, treated at 500 ° C. for 1 hour, then purged with N ₂ , after thoroughly expelling the H _2, it was evaluated for catalytic performance.
For the performance evaluation, an atmospheric pressure fixed bed flow type reactor was used, and ethanol / isooctane = 50: 50 weight ratio mixed fuel was used as a model fuel and supplied to the catalyst layer at a mixed fuel flow rate of 3.0 cc / min.
Therefore, LHSV (liquid space velocity) is about 30. At this time, N ₂ was supplied as a carrier gas at a rate of 0.5 L per minute.
The catalyst layer inlet temperature was set in a suitable temperature range from 100 ° C. to 400 ° C., and ethanol and hydrogen were quantified using a gas chromatograph. Ethanol at the catalyst layer inlet, ethanol and H ₂ at the outlet were quantified, and the ethanol conversion was calculated by the following formula 1.

That is, the higher the ethanol conversion rate, the better the fuel conversion performance. In this example, the ethanol conversion rate as well as the H ₂ production ability are also indices for judging the performance. This is because H ₂ is a clean fuel with a high combustion rate, a high octane number, and favorable characteristics for combustion of an internal combustion engine.

  As shown in FIG. 2, all of the fuel conversion / supply catalysts have been ethanol-converted from a low temperature range of about 150 ° C., and remarkable hydrogen production is seen at 250 ° C., which is sufficient even under low exhaust temperature conditions of a high efficiency engine. It can be seen that it can work.

It is the schematic which shows an example of the combustion system to which the catalyst for fuel conversion and supply of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Heat exchanger 2 'Heat exchanger 3 Fuel conversion and supply catalyst

Claims (9)

A catalyst used in an apparatus for supplying a fuel component to an internal combustion engine,
Containing platinum and a compound containing at least one element selected from the group consisting of cerium, titanium, zirconia, niobium, alkali metals and alkaline earth metals,
A fuel conversion / supply catalyst, wherein at least part of a mixed fuel comprising a hydrocarbon fuel and an oxygen-containing compound fuel is converted into another fuel component. A catalyst used in an apparatus for supplying a fuel component to an internal combustion engine,
Copper and an oxide containing at least one element selected from the group consisting of aluminum, silicon, zinc and magnesium,
A fuel conversion / supply catalyst, wherein at least part of a mixed fuel comprising a hydrocarbon fuel and an oxygen-containing compound fuel is converted into another fuel component.   A fuel conversion / supply device comprising the fuel conversion / supply catalyst according to claim 1. In converting and supplying fuel using the fuel conversion and supply device according to claim 3,
When contacting a mixed fuel composed of a hydrocarbon-based fuel and an oxygen-containing compound fuel with a fuel conversion / supply catalyst, temperature control of the catalyst or its vicinity is performed using waste heat from an internal combustion engine,
A fuel conversion / supply method, wherein at least a part of the mixed fuel is converted into another fuel component and supplied to an internal combustion engine.   5. The fuel conversion / supply method according to claim 4, wherein at least a part of exhaust gas from the internal combustion engine is mixed with a mixed fuel and supplied to the catalyst.   6. The fuel conversion / supply method according to claim 5, wherein the oxygen concentration of the mixed gas obtained by the mixing process is controlled.   The fuel conversion / supply method according to any one of claims 4 to 6, wherein a pressure in a reaction field of the fuel conversion / supply catalyst is controlled.   The fuel conversion / supply method according to any one of claims 4 to 7, wherein the oxygen-containing compound fuel is ethanol fuel.   The fuel conversion / supply method according to any one of claims 4 to 8, wherein the fuel conversion / supply catalyst is used by being applied to a metal carrier having three-dimensional continuous pores.

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