JP4860226B2 - Partial oxidation reforming catalyst and partial oxidation reforming method - Google Patents

Description

  The present invention relates to a partial oxidation reforming catalyst for hydrocarbon compounds, in particular, sulfur suitably used for converting hydrocarbon compounds containing sulfur into a mixed gas containing carbon monoxide and hydrogen by a partial oxidation reforming reaction. The present invention relates to a partial oxidation reforming catalyst and a partial oxidation reforming method excellent in poisoning resistance.

The partial oxidation reforming technique for hydrocarbon compounds is a method for producing a hydrogen-containing gas by partially oxidizing a hydrocarbon compound with an oxygen-containing gas such as air in the presence of a catalyst in a hydrogen production process. It is well known that the activity of a partial oxidation reforming catalyst is significantly reduced by sulfur. For the purpose of preventing catalyst deterioration due to sulfur, for example, a method for reducing the sulfur concentration in the raw material to the limit has been proposed. (Patent Document 1). However, this method has drawbacks such as high cost because it requires a high degree of desulfurization process.
JP-A-2-302303

An object of the present invention is to provide a partial oxidation reforming catalyst in which the activity of the partial oxidation reforming reaction does not decrease even when the hydrocarbon compound as a raw material contains sulfur at a certain concentration or more.
Another object of the present invention is to produce a mixed gas containing carbon monoxide and hydrogen from hydrocarbon compounds that has long-term stability even when the hydrocarbon compounds as raw materials contain sulfur at a certain concentration or more. An oxidation reforming method is provided.

  In the case of producing a mixed gas containing carbon monoxide and hydrogen by a partial oxidation reforming reaction of hydrocarbon compounds, the present inventors are long even when the raw hydrocarbon compounds contain a certain concentration of sulfur or more. As a result of diligent research on a method that can ensure the stability of the period, it was found that the stability of the long-term catalytic activity was ensured by using a specific partial oxidation reforming catalyst, and the present invention was completed. is there.

  That is, the present invention relates to hydrocarbon compounds containing sulfur in which rhodium and at least one metal selected from Group VIII metals other than rhodium are supported on a carrier containing alumina and zirconia. The present invention relates to a partial oxidation reforming catalyst.

The present invention also relates to the partial oxidation reforming catalyst, wherein the metal selected from Group VIII metals of the periodic table other than rhodium is platinum or palladium.
The present invention also relates to the partial oxidation reforming catalyst, wherein the rhodium content in the catalyst is 0.05 to 20% by mass.
Further, in the present invention, the partial oxidation reforming catalyst is characterized in that the content of a metal selected from Group VIII metals other than rhodium in the catalyst is 0.01 to 10 times the rhodium content. About.

Further, the present invention uses any one of the partial oxidation reforming catalysts to produce a mixed gas containing carbon monoxide and hydrogen from a raw material mixture containing hydrocarbon compounds containing sulfur, water vapor and air. The present invention relates to a characteristic partial oxidation reforming method.
The present invention also relates to the partial oxidation reforming method, wherein the sulfur content of the hydrocarbon compound containing sulfur is 10 mass ppb to 50 mass ppm.

Hereinafter, the present invention will be described in detail.
The partial oxidation reforming reaction in the present invention is a reaction in which hydrocarbon compounds are reacted with an oxygen-containing gas such as water vapor and air in the presence of a catalyst to convert to a reforming gas containing carbon monoxide and hydrogen. Say.

  The hydrocarbon compounds used as a raw material are organic compounds having 1 to 40 carbon atoms, preferably 1 to 30 carbon atoms. Specific examples include saturated aliphatic hydrocarbons, unsaturated aliphatic hydrocarbons, aromatic hydrocarbons, etc. In addition, saturated aliphatic hydrocarbons and unsaturated aliphatic hydrocarbons are linear or cyclic. Can be used regardless. Aromatic hydrocarbons can be used regardless of whether they are monocyclic or polycyclic. Such hydrocarbon compounds can contain substituents. As the substituent, either a chain or a ring can be used, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an alkylaryl group, and an aralkyl group. These hydrocarbon compounds may be substituted with a substituent containing a hetero atom such as a hydroxy group, an alkoxy group, a hydroxycarbonyl group, an alkoxycarbonyl group, or a formyl group.

  Specific examples of hydrocarbon compounds that can be used in the present invention include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane. , Saturated aliphatic hydrocarbons such as eicosan, unsaturated aliphatic hydrocarbons such as ethylene, propylene, butene, pentene and hexene, cyclic hydrocarbons such as cyclopentane and cyclohexane, aromatic hydrocarbons such as benzene, toluene, xylene and naphthalene Can be mentioned. Moreover, these mixtures can also be used suitably, For example, the material which can be obtained cheaply industrially, such as natural gas, LPG, naphtha, gasoline, kerosene, and light oil, can be mentioned. Specific examples of the hydrocarbon compound having a substituent containing a hetero atom include methanol, ethanol, propanol, butanol, dimethyl ether, phenol, anisole, acetaldehyde, acetic acid and the like.

  Moreover, the raw material which contains hydrogen, water, a carbon dioxide, carbon monoxide etc. in the said raw material can also be used. For example, when hydrodesulfurization is carried out as a pretreatment of the raw material, the hydrogen residue used in the reaction can be used as it is without separation.

  The raw material hydrocarbon compounds used in the present invention contain sulfur at a certain concentration or higher. The concentration is preferably 1 capacity ppb or more, more preferably 5 capacity ppb or more, and still more preferably 10 capacity ppb or more when the volume is converted assuming that the sulfur amount is vaporized as a single atom. On the other hand, on the mass basis, the mass of the sulfur atom is preferably 10 mass ppb or more, more preferably 50 mass ppb or more, and still more preferably 100 mass ppb or more. On the other hand, when the sulfur concentration in the raw material is too high, even the catalyst of the present invention may be deactivated, preferably 50 ppm by mass or less, more preferably 20 ppm by mass or less. For this reason, if necessary, desulfurization of the raw material to a certain concentration or less can be preferably performed in advance. In this case, there is no restriction | limiting in particular in the sulfur concentration in a starting material, If it can convert into the said sulfur concentration in a desulfurization process, it can be used.

Although there is no particular limitation on the desulfurization method, a method in which hydrodesulfurization is performed in the presence of an appropriate catalyst and hydrogen and the generated hydrogen sulfide is absorbed by zinc oxide or the like can be given as an example. Examples of the catalyst that can be used in this case include catalysts containing nickel-molybdenum, cobalt-molybdenum, and the like as components. On the other hand, a method of sorbing a sulfur component in the presence of an appropriate sorbent and, if necessary, coexisting with hydrogen can also be employed. Examples of the sorbent that can be used in this case include a sorbent mainly composed of copper-zinc or nickel-zinc as a main component as disclosed in Japanese Patent No. 2654515, Japanese Patent No. 2688749, and the like. And so on.
There is no restriction | limiting in particular also about the implementation method of a desulfurization process, You may implement by the desulfurization process installed immediately before the partial oxidation reforming reactor, and you may process in an independent desulfurization process.

The partial oxidation reforming catalyst of the present invention is a catalyst in which rhodium and at least one metal selected from Group VIII metals of the periodic table other than rhodium are supported on a carrier.
Specific examples of Group VIII metals other than rhodium include noble metals such as ruthenium, palladium, iridium, osmium, iridium, and platinum, iron, cobalt, nickel, and the like. Among these, platinum or palladium is preferable, and palladium is particularly preferable.

The rhodium content in the catalyst of the present invention is preferably 0.05 to 20% by mass as rhodium atoms, more preferably 0.1 to 10% by mass, and still more preferably 0.3 to 5% by mass. is there. When the rhodium content is more than 20% by mass, the active metal agglomeration increases and the proportion of the metal that appears on the surface is extremely reduced. On the other hand, when the rhodium content is less than 0.05% by mass. Is not preferable because a large amount of a supported catalyst is required because the catalyst cannot exhibit sufficient activity, and problems such as the need to enlarge the reactor more than necessary arise.
Further, the content of the Group VIII metal other than rhodium is preferably 0.01 to 10 times by weight of the rhodium content, more preferably 0.05 to 5 times by weight, still more preferably 0.1 to 0.1 times. The range is 3 times the weight.

As the carrier, a carrier containing alumina and zirconia is used. The mixing ratio of alumina and zirconia in the support can be appropriately determined, but the content of alumina in the support is preferably 70% by mass or more, more preferably 75% by mass or more, and further preferably 80% by mass. That's it.
The weight of zirconia is preferably 1 to 30% by mass, more preferably 1.5 to 25% by mass, and still more preferably 2 to 20% by mass with respect to the alumina weight. If it is less than this, the effects expected of zirconia, such as prolonging the catalyst life, will be reduced. On the other hand, if it is more than this, the surface area of the catalyst will be small, which is not preferable.

  Components other than alumina and zirconia include oxides of alkali metals such as lithium, sodium, potassium and cesium, oxides of alkaline earth metals such as magnesium, calcium, strontium and barium, and periodic rules such as scandium and yttrium. Table IIIA Group oxides of metals, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and other rare earth metal oxides, titanium, hafnium, etc. Unitary oxides such as Group IVA metal oxides and silicon oxides, and mixed oxides in which two or more of these oxides are mixed in any ratio can also be used.

  There is no restriction | limiting in particular regarding the loading method of an active metal, Well-known methods, such as a normal impregnation method, are employable. Usually, as a salt or complex of an active metal, it is dissolved in a solvent such as water, ethanol or acetone and impregnated on a carrier. As the metal salt or metal complex to be supported, chloride, nitrate, sulfate, acetate, acetoacetate, etc. are preferably used. Specifically, ruthenium chloride, ruthenium acetylacetonate, rhodium chloride, rhodium nitrate, chloride Palladium, osmium chloride, iridium chloride, chloroplatinic acid, cobalt nitrate, iron nitrate, nickel nitrate, cobalt chloride, iron chloride, nickel chloride, cobalt acetate, iron acetate, nickel acetate, cobalt acetylacetonate, iron acetylacetonate, nickel A compound such as acetylacetonate can be mentioned, but is not limited thereto.

  There is no restriction | limiting in particular about the form of the catalyst to be used. For example, it is possible to use a catalyst formed by tableting and pulverized to an appropriate range, an extruded catalyst, an extruded catalyst added with an appropriate binder, a powdered catalyst, and the like. Alternatively, the active metal is applied to a carrier formed by tableting and pulverizing to an appropriate range after being pulverized, an extruded carrier, a powder or a carrier shaped into a spherical shape, ring shape, tablet shape, cylindrical shape, flake shape, etc. A supported catalyst or the like can be used. Further, a catalyst obtained by forming the catalyst itself into a monolith shape, a honeycomb shape, or the like, or a monolith using a suitable material, a honeycomb coated with a catalyst, or the like can be used.

  In the partial oxidation reforming reaction of the present invention, the amount of steam introduced into the reaction system is a value defined as the ratio of the number of moles of water molecules to the number of moles of carbon atoms contained in the raw material hydrocarbon compounds (steam / carbon ratio). Is preferably in the range of 0.3 to 10, more preferably 0.5 to 5, and still more preferably 1 to 3. If this value is smaller than the above range, coke is liable to deposit on the catalyst and the hydrogen fraction cannot be increased. On the other hand, if it is larger, the reforming reaction proceeds but the steam generation facility and steam recovery facility May cause enlargement. The introduction method is not particularly limited, but may be introduced into the reaction zone at the same time as the raw material hydrocarbon compounds, or may be introduced one by one from separate positions in the reactor zone or divided into several times. Also good.

  The amount of oxygen introduced into the reaction system is preferably a value defined as a ratio (oxygen / carbon ratio) of the number of moles of oxygen molecules to the number of moles of carbon atoms contained in the raw material hydrocarbon compounds. More preferably, it is in the range of 0.2 to 0.8, and more preferably 0.3 to 0.6. If this value is smaller than the above range, the hydrocarbon may not be completely converted to a mixed gas containing carbon monoxide and hydrogen. On the other hand, if it is larger, the partial oxidation reaction proceeds but the hydrogen fraction can be increased. become unable.

The space velocity of the flow material introduced into the reactor (raw material + steam + air) (GHSV) is preferably 100～100,000H ^-1, more preferably 300～50,000H ^-1, more preferably 500-30 In the range of 1,000 h ⁻¹ , it is set in view of the respective purposes.
Although reaction temperature is not specifically limited, Preferably it is 200-1000 degreeC, More preferably, it is 300-900 degreeC, More preferably, it is the range of 500-800 degreeC.
The reaction pressure is not particularly limited and is preferably carried out in the range of atmospheric pressure to 20 MPa, more preferably atmospheric pressure to 5 MPa, and further preferably atmospheric pressure to 1 MPa. It is also possible to implement.

  As a form of the reactor used for the partial oxidation reforming reaction, a fixed bed flow type reactor is preferably used. The shape of the reactor may be any known shape depending on the purpose of each process, such as a cylindrical shape or a flat plate shape. A fluidized bed reactor can also be used.

  When partial oxidation reforming is performed using the partial oxidation reforming catalyst of the present invention, hydrocarbon compounds containing sulfur are converted into a mixed gas containing hydrogen and carbon monoxide by a partial oxidation reforming reaction. Since the sulfur poisoning stability, which has been regarded as a problem in the past, is improved, a stable reaction system can be provided. As a result, stable production of a mixed gas containing hydrogen and carbon monoxide can be achieved, and hydrocarbon compounds containing sulfur can be used as fuel for fuel cells or a raw material thereof.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.

[Preparation of carrier]
(1) A carrier 1 is a γ-alumina molded body having a surface area of 165 g / cm ² .
(2) A γ-alumina molded body having a surface area of 165 g / cm ² was supported by an incipient wetness method using a 5M zirconium nitrate aqueous solution so that the amount of supported ZrO ₂ was 12% by mass, and dried at 120 ° C. for 12 hours. Air calcination at 800 ° C. for 3 hours is used as carrier 2.

[Preparation of catalyst]
(A) The carrier 1 is supported by an incipient wetness method using a 1M aqueous rhodium chloride solution so that the supported amount as rhodium metal is 2% by mass, dried at 120 ° C. for 12 hours, and then at 800 ° C. for 3 hours. Air calcination is performed to obtain catalyst A.
(B) The carrier 1 is supported by an incipient wetness method using a 1M platinum chloride aqueous solution so that the supported amount as platinum metal is 2% by mass, dried at 120 ° C. for 12 hours, and then at 800 ° C. for 3 hours. Air calcination is performed to obtain catalyst B.
(C) The carrier 2 was supported by an incipient wetness method using a 1M aqueous rhodium chloride solution so that the supported amount as rhodium metal was 2% by mass, dried at 120 ° C. for 12 hours, and then at 800 ° C. for 3 hours. Air calcination is performed to obtain catalyst C.

(D) A 1M aqueous solution of rhodium chloride weighed so that the supported amount as rhodium metal is 2% by mass on the carrier 1, and 1M chloride is added so that the supported amount as platinum metal is 0.2% by mass. An active metal is supported by an incipient wetness method using a solution to which an aqueous platinum solution is added, dried at 120 ° C. for 12 hours, and then air calcined at 800 ° C. for 3 hours to obtain catalyst D.
(E) 1M nitric acid so that the support amount as palladium metal becomes 0.2% by mass in the 1M rhodium chloride aqueous solution weighed so that the support amount as rhodium metal becomes 2% by mass on the carrier 1; An active metal is supported by an incipient wetness method using a solution to which an aqueous palladium solution is added, dried at 120 ° C. for 12 hours, and then air calcined at 800 ° C. for 3 hours to obtain catalyst E.

(F) A 1M rhodium chloride solution weighed so that the supported amount as rhodium metal is 2% by mass on the carrier 2, and 1M chloride is added so that the supported amount as platinum metal is 0.2% by mass. An active metal is supported by an incipient wetness method using a solution to which an aqueous platinum solution is added, dried at 120 ° C. for 12 hours, and then air calcined at 800 ° C. for 3 hours to obtain catalyst F.
(G) A 1M aqueous solution of rhodium chloride weighed so that the supported amount as rhodium metal is 2% by mass on the carrier 2, and 1M nitric acid so that the supported amount as palladium metal is 0.2% by mass. An active metal is supported by an incipient wetness method using a solution to which an aqueous palladium solution is added, dried at 120 ° C. for 12 hours, and then air calcined at 800 ° C. for 3 hours to obtain catalyst G.

[Comparative Example 1]
Catalyst A 20 cm ³ is charged into a fixed bed flow reactor, and a mixed gas of No. 1 kerosene (sulfur content: 49 mass ppm as sulfur atom) and steam and air is used as a raw material, GHSV is 12000 h ⁻¹ , reaction temperature is 700 ° C. A partial oxidation reforming reaction was performed under the conditions. The reaction conditions are shown in Table 1.

[Comparative Examples 2 to 5]
The reaction was performed in the same manner as in Comparative Example 1 except that the catalysts B to E were used instead of the catalyst A.

[Examples 1-2]
The reaction was performed in the same manner as in Comparative Example 1 except that the catalysts FG were used instead of the catalyst A.

[Comparative Example 6]
In Comparative Example 1, partial oxidation was performed in the same manner as Comparative Example 1 except that No. 1 kerosene (sulfur content: 12 mass ppm as sulfur atom) was used instead of No. 1 kerosene (sulfur content: 49 mass ppm as sulfur atom). A reforming reaction was performed.

[Comparative Examples 7 to 10]
The reaction was performed in the same manner as in Comparative Example 6 except that the catalysts B to E were used instead of the catalyst A.

[Examples 3 to 4]
The reaction was performed in the same manner as in Comparative Example 6 except that the catalysts F to G were used instead of the catalyst A.

Results of the degradation over time of the reactions using the catalysts A, B, C, D, E, F and G, organized by conversion rate after 5 hours / conversion rate after 30 minutes × 100 (degradation index) Are shown in Table 2 and Table 3. Here, the conversion rate is a value represented by (CO + CO ₂ + CH ₄ carbon atoms) / (number of hydrocarbon carbon atoms in the raw material) × 100.

  As is apparent from Tables 2 and 3, the deterioration index (conversion rate after 5 hours reaction time / conversion rate after 30 minutes reaction time) is obtained by supporting platinum or palladium in addition to rhodium on a support containing alumina and zirconium. ) Is large, it can be seen that the deterioration due to sulfur poisoning is alleviated.

Claims (6)

Rhodium, platinum or palladium and the alumina and made of zirconia supported on a carrier containing sulfur comprising hydrocarbon compounds partial oxidation reforming catalyst. The partial oxidation reforming catalyst according to claim 1, wherein the mixing ratio of alumina and zirconia in the support is 70 to 99 mass% for alumina and 1 to 30 mass% for zirconia.   The partial oxidation reforming catalyst according to claim 1, wherein the rhodium content in the catalyst is 0.05 to 20% by mass as rhodium atoms. 2. The partial oxidation reforming catalyst according to claim 1, wherein the content of platinum or palladium in the catalyst is 0.01 to 10 times the content of rhodium.   Using the partial oxidation reforming catalyst according to any one of claims 1 to 4, a mixed gas containing carbon monoxide and hydrogen is produced from a raw material mixture containing hydrocarbon compounds containing sulfur, steam and air. A partial oxidation reforming method characterized by manufacturing.   The partial oxidation reforming method according to claim 5, wherein the sulfur content of the hydrocarbon compound containing sulfur is 10 mass ppb to 50 mass ppm as a sulfur atom.