RU2455068C2 - Catalyst, preparation method thereof and method of producing synthetic gas from synthetic hydrocarbon fuel - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to catalysts for vapour conversion of synthetic fuel. Described is a catalyst for producing synthetic gas via vapour conversion of synthetic hydrocarbon fuel, preferably methanol, characterised by that the catalyst is a catalytic structured block with a gas distribution system consisting of alternating corrugated and flat catalytically active bands which form channels; the catalyst contains copper, zinc, chromium and aluminium compounds as active components, said compounds being in the following amounts, wt %: copper oxide 5-15, chromium oxide 0.4-2.6, zinc oxide 3-16 and aluminium oxide 2-8, reinforced metal porous support - the balance up to 100. Described is a method of preparing said catalyst by depositing active components onto the support by impregnating a heat-resistant reinforced metal porous support with a solution of copper, chromium, zinc and aluminium salts, drying and calcining at 400-450°C, followed by cutting catalytically active bands from the obtained reinforced catalyst and forming the catalyst, which is a catalytic structured block with a gas distribution system consisting of alternating corrugated and flat catalytically active bands which form channels. Described is a method of producing synthetic gas through vapour conversion of methanol using the catalyst described above.

EFFECT: high efficiency of the process of producing synthetic gas.

7 cl, 1 tbl, 4 ex

Description

The invention relates to catalysts for the steam conversion of synthetic fuels, mainly methanol, to produce synthesis gas. Synthesis gas can be used in chemical production, for combustion in catalytic thermal installations, in hydrogen energy, including in fuel cells (FC).

To produce hydrogen, steam or autothermal reforming is usually used as the first stage of the process, as a result of which synthesis gas is obtained from methanol or other types of fuel. Steam conversion of methanol in comparison with other types of reforming provides the maximum yield of hydrogen (about 70-74%) and therefore can be considered as one of the priority ones. Methanol is also of considerable interest due to the availability of raw materials and the relatively low temperature of the steam reforming process. However, for the implementation of the endothermic steam reforming reaction of methanol in order to obtain synthesis gas, it is necessary to supply heat to the reaction zone from an external source. Currently, tubular apparatus with a fixed catalyst bed is used to carry out the steam reforming reaction. Moreover, the performance of such a reactor with a fixed catalyst bed depends not only on the activity of the catalyst used, but also on the intensity of heat transfer through the apparatus wall and the radial thermal conductivity of the grain layer. The heat transfer coefficients through the apparatus wall and the radial thermal conductivity of the layer are determined by the grain size of the catalyst and the linear velocity of the gas in the reactor and, therefore, the possibility of their increase is limited. In this regard, to reduce these thermal resistances and increase the productivity of a unit volume of the reactor, it is necessary to develop new approaches to the organization of the process.

The invention solves the problem of efficient generation of hydrogen-containing gas by steam conversion of synthetic fuels, mainly methanol, for use in various types of power plants.

Since steam conversion is an endothermic process, for its implementation it is necessary to supply heat to the reaction zone. Therefore, a solution to this problem can be found in the thermal conjugation of the endothermic reaction of methanol steam reforming and the catalytic oxidation of, for example, a hydrogen-containing anode gas remaining after a fuel battery (S. Nagano et al., 2002; L. Pan and S. Wang, 2005; J .Lattner and M. Harold, 2005; W. Cao, 2006), or hydrocarbon feed gas.

The high thermal conductivity of the structured metal-porous catalyst and the metal wall, the practical absence of spatial separation of the reaction zones can provide the necessary heat coupling of these reactions. This method of carrying out the process allows you to create a device that has the advantages of both existing versions of the steam reformer (high hydrogen output) and autothermal devices (low weight and size, low hydraulic resistance, low inertia). In our case, the device consists of two catalytic blocks coupled by heat. The first block consists of endothermic channels of a metalloporous methanol steam reforming catalyst, where the following reactions take place:

CH ₄ O + H ₂ O = CO ₂ + 3H ₂ - steam methanol conversion;

СО + H ₂ O = СО ₂ + Н ₂ - shift reaction;

CH ₄ O = CO + 2H ₂ - decomposition of methanol.

The second block consists of exothermic channels of the deep oxidation catalyst of the initial fuel, where the following exothermic reactions proceed:

CH ₄ O + 1.5O ₂ = СО ₂ + 2Н ₂ O - methanol oxidation at the time of starting and heating;

Н ₂ + 0.5O ₂ = Н ₂ O - oxidation of a hydrogen-containing gas remaining after a fuel battery.

Currently, such heat-coupled reformers are of considerable interest due to the development of high-temperature proton-exchange fuel cells (NT PEMFCs), which place high demands on the low concentration of CO in the synthesis gas (A.Reiche et al., 2006). The use of methanol to generate a hydrogen-containing gas using steam reforming of methanol with a ratio of H ₂ O / MeOH> 1.3 allows us to obtain a CO concentration of not more than 3% in reaction products that can be used to supply a PEMFC battery to NT.

In the present invention, the metal-porous block methanol steam reforming catalyst allows heat coupling between the endothermic methanol steam reforming reaction and the exothermic oxidation reaction of methanol and / or anode gas.

The problem is solved using a metalloporous block catalyst for the steam conversion of methanol.

The catalyst for producing synthesis gas by steam conversion of synthetic hydrocarbon fuels, mainly methanol, characterized in that it is a catalytic structured unit with a gas distribution system, consisting of alternating corrugated and flat catalytically active tapes forming channels.

Reinforced porous material containing oxides of copper, zinc, chromium and aluminum as active components is used as a metal-porous block catalyst for the steam conversion of methanol. The use of a metalloporous block catalyst on a stainless steel substrate allows thermal coupling between the endothermic and exothermic zones. The metal-porous block catalyst is a monolith formed from flat and corrugated catalytically active tapes forming a channel-like structure of the catalyst layer. The diameter of the channel is determined by the size of the corrugation of the catalytically active tape.

Thus, a porous structure is formed, consisting of large transport pores - channels (due to the corrugation) and small pores (due to the porosity of the mesh). This creates favorable conditions for the transfer of heat from the exothermic oxidation reaction of methanol and / or anode gas (hydrogen) to the zone of the endothermic reaction of steam methanol conversion.

The use of a structured block catalyst on a stainless steel substrate allows thermal coupling between the endothermic and exothermic zones.

An analysis of the literature and patent data shows that the main direction of development of methanol steam reforming catalysts is associated with low-temperature shift catalysts (working range 200-275 ° С), which include supported oxides of copper, zinc, chromium and aluminum as active components. The disadvantage of these catalysts is their pyrophoricity (the ability to self-ignite and / or oxidize upon contact with air) and deactivation after prolonged use. Another area of development of methanol steam reforming catalysts is associated with high-temperature methanol synthesis catalysts. These catalysts do not contain copper oxides and include supported iron oxides as an active component. These catalysts are less pyrophoric and exhibit a high activity in the methanol steam reforming reaction. The disadvantage of these catalysts is a higher temperature range.

Closest to our proposed catalyst is a catalyst for producing synthesis gas by steam methanol conversion [US 2006/0236607, A1, B01J 8/00, 10.26.2006]. The catalyst is a fixed bed of catalyst grains. The fixed catalyst bed is alumina grains coated with active components of copper oxide, chromium oxide, zinc oxide and calcium aluminate. The process is carried out at an inlet temperature of the mixture of 500 ° C.

The disadvantage of this catalyst is that the performance of a reactor with a fixed catalyst bed depends not only on the activity of the catalyst used, but also on the intensity of heat transfer through the apparatus wall and the radial thermal conductivity of the grain layer. In this case, the heat transfer coefficients through the apparatus wall and the radial thermal conductivity of the layer are determined by the grain size of the catalyst and the linear velocity of the gas in the reactor and, therefore, the possibility of their increase is limited. In addition, the structure of the carrier has a large variation in pore size and high hydraulic resistance. It has high porosity and closed pores, which reduces thermal conductivity and specific surface, as well as mechanical characteristics.

The invention solves the problem of preparing an effective catalyst for producing synthesis gas by steam methanol conversion.

The catalyst should have the following properties:

- high activity and thermal stability;

- thermal conductivity of the catalyst layer at the level of 1-5 watts / mK;

- the possibility of using the catalyst as structural elements of the reactor structure;

- low cost;

- the correspondence of the thermal expansion coefficients of the carrier material and the catalytically active layer;

- low hydraulic resistance;

- good adhesion of the catalyst layer and the metal surface.

The problem is solved by a catalyst for producing synthesis gas by steam reforming of synthetic hydrocarbon fuels, mainly methanol, which is a catalytic structured unit with a gas distribution system consisting of alternating corrugated and flat catalytically active tapes forming channels.

The size of the corrugation is approximately 2 mm.

As a steam reforming catalyst, a catalyst containing copper, zinc, chromium and aluminum compounds as active components is used.

The catalyst contains these components in the following amounts, wt.%: Copper oxide - 5-15, chromium oxide - 0.4-2.6, zinc oxide - 3-16 and aluminum oxide - 2-8, reinforced metal-porous support - the rest is up to one hundred%.

The reinforced metal-porous carrier can be made of stainless woven fabric of plain weave, wire grade 12X18H9, fechral wire X23YU5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY, stainless steel woven mesh twill weave C 120N grade 18 CX12 grade 18.

The problem is also solved by the method of preparing a catalyst for producing synthesis gas by steam conversion of synthetic hydrocarbon fuels, mainly methanol, applying the active component to a carrier, which is prepared by impregnating the carrier with a solution of copper, chromium, zinc and aluminum salts, drying and subsequent calcining at 400-450 ° C , a heat-resistant reinforced metal-porous carrier is used as a carrier, and a catalyst of the following composition is obtained, containing, wt.%: copper oxide - 5-15, chromium oxide - 0.4-2.6, zinc oxide - 3-16 and oxy d aluminum - 2-8, reinforced metal-porous carrier - the rest is up to 100%.

The reinforced metal-porous carrier can be made of stainless woven fabric of plain weave, wire grade 12X18H9 according to GOST 3187-76, Fe23 wire X23U5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY, stainless steel wire mesh Twill 18 binder.

The problem is also solved by the method of producing synthesis gas by steam reforming of methanol, which is carried out using the catalyst described above. The content of CO in the reaction products is not more than 3%.

The problem is solved by the use of metal-porous monolithic catalysts on heat-resistant mesh carriers with significant longitudinal and radial thermal conductivity of a reinforced metal-porous carrier having high thermal conductivity, developed surface, regular structure and mechanical strength, low hydraulic resistance.

It is proposed to use a heat-resistant reinforced metal-porous carrier made of mesh heat-resistant steels, on which active components are applied, as a carrier. This technology provides mechanical strength, thermal conductivity, regularity and uniformity of structure, low hydraulic resistance.

In this case, it becomes possible, by choosing the chemical composition of the carrier, to provide optimal characteristics for each specific application.

Thus, the problem is solved by the development of a catalyst for producing synthesis gas through steam reforming of a synthetic hydrocarbon oxygen-containing fuel (methanol), which is a metal-porous monolithic catalyst. The catalyst contains copper oxide, chromium oxide, zinc oxide and aluminum oxide deposited on a heat-resistant reinforced metal-porous carrier, which can be used as a reinforced stainless steel mesh, with the content of components in the catalyst, wt.%: Copper oxide - 5-15, chromium oxide - 0.4-2.6, zinc oxide - 3-16 and aluminum oxide - 2-8, reinforced metal-porous carrier - the rest is up to 100%.

The heat-resistant reinforced metal-porous carrier is a mesh material of industrial production.

The problem is also solved by the method of preparation of the catalyst, which includes a sequence of operations using advanced technology.

1. Stripping and annealing of the reinforcing mesh is carried out at 600 ° C in order to remove the protective coating and improve the molding properties.

2. The preparation of a solution with a given ratio of active components includes the dissolution in water of nitric salts of copper, chromium, zinc and aluminum.

3. Precipitation of the active component. The prepared carrier is impregnated several times in an aqueous solution of salts with a predetermined ratio of active components until the mass of the catalyst increases by 20-25 wt.%. After each impregnation process, the sample is dried in air and heated to 400-450 ° C for a short period.

4. Heat treatment is carried out for 4-5 hours. The temperature of the heat treatment depends on the heat resistance of the active component.

5. Cutting reinforced catalyst tapes of a given width. Ribbons are corrugated using specially designed crimpers.

6. Preparation of catalysts of regular structure.

An aqueous solution of nitrate salts of copper, chromium, zinc and aluminum is applied several times to a monolithic metal-porous catalyst based on a stainless mesh (75-80 wt.%), Until the mass of the catalyst increases by 15-20 wt.%. After each application of the active components, the catalyst is dried and calcined at 400-450 ° C.

The heat-resistant metal-porous carrier can also be made of stainless woven fabric of linen weave, wire grade 12X18H9, fechral wire X23Yu5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY, stainless steel woven mesh twill weave according to GOST 82 1818 18 C1882 18 1826 18 C .

The problem is also solved by the method of producing synthesis gas by steam reforming of methanol in the presence of the above catalyst.

The resulting catalyst is characterized by high thermal conductivity and activity in the reaction of steam reforming of methanol at a mixture temperature of 275-300 ° C at the outlet of the catalyst. Under these conditions, the reaction products provide a H ₂ content _of up to 74% and CO about 1% (given the concentration in the dry mixture).

Distinctive features of the proposed metalloporous block catalyst are:

1. The composition of the methanol steam reforming catalyst, containing wt.%: Copper oxide - 5-15, chromium oxide - 0.4-2.6, zinc oxide - 3-16 and aluminum oxide - 2-8, reinforced metal-porous carrier - the rest up to 100%.

2. Reinforced metal-porous carrier, can be made of stainless woven fabric of plain weave, wire grade 12X18H9, fecal wire X23YU5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY, stainless steel woven wire mesh twill weave according to GOST 12 C18X18 18 120 120 120 120 -76.

The use of a reinforced metal-porous carrier as a carrier increases the thermal conductivity of the catalyst, and also makes it possible to produce a structured (block) catalyst.

3. The metal-porous block catalyst allows for the supply of heat necessary for the endothermic reaction of steam reforming of methanol flowing on the catalyst.

4. The metal-porous block catalyst ensures the CO content in the steam conversion products at a level of no more than 3%, which makes it possible to supply the generated hydrogen-containing gas to the NT PEMFC battery.

The invention is illustrated by the following examples.

Example 1

The methanol steam reforming catalyst, containing, wt.%: Copper oxide - 5.2, chromium oxide - 2.6, zinc oxide - 3.2 and aluminum oxide - 5.0, reinforced metal-porous support - the rest is up to 100%, served 1.65 g / min of an aqueous methanol mixture of H ₂ O / CH ₃ OH (mol) = 1.3.

The content of dry synthesis gas,%:

hydrogen 72.9

carbon monoxide 2.8

carbon dioxide 22.7.

Example 2

The methanol steam reforming catalyst, containing, wt.%: Copper oxide - 7.6, chromium oxide - 0.4, zinc oxide - 5.8 and aluminum oxide - 6.2, reinforced metal-porous support - the rest is up to 100%, served 1.65 g / min of an aqueous methanol mixture of H ₂ O / CH ₃ OH (mol) = 1.3.

The content of dry synthesis gas,%:

hydrogen 73

carbon monoxide 2.6

carbon dioxide 22.9.

Example 3

The methanol steam reforming catalyst, containing, wt.%: Copper oxide - 5.2, chromium oxide - 2.6, zinc oxide - 3.2 and aluminum oxide - 5.0, reinforced metal-porous support - the rest is up to 100%, served 2.45 g / min of an aqueous methanol mixture of H ₂ O / CH ₃ OH (mol) = 2.5.

The content of dry synthesis gas,%:

hydrogen 71.2

carbon monoxide 1.6

carbon dioxide 22.3

Example 4

The methanol steam reforming catalyst, containing, wt.%: Copper oxide - 7.6, chromium oxide - 0.4, zinc oxide - 5.8 and aluminum oxide - 6.2, reinforced metal-porous support - the rest is up to 100%, served 2.45 g / min of an aqueous methanol mixture of H ₂ O / CH ₃ OH (mol) = 2.5.

The content of dry synthesis gas,%:

hydrogen 74

carbon monoxide 1.0

carbon dioxide 23.2.

The present invention allows to create an effective metalloporous block catalyst for the generation of hydrogen-containing gas by steam reforming of synthetic fuels (methanol). The catalyst generates synthesis gas with a CO content of not more than 3%.

The invention can be used in hydrogen energy (in TE NT PEMFC).

No. The consumption of water-methanol mixture for conversion, g / min The temperature at the outlet of the catalyst, ° C The composition of the conversion products,% Degree of conversion H ₂ With CO ₂ one 1.65 (1.3: 1) 303 72.9 2.8 22.7 98.5 2 1.65 (1.3: 1) 290 73 2.6 22.9 98.6 3 2.45 (2.5: 1) 305 71.2 1.6 22.3 98.8 four 2.45 (2.5: 1) 272 74.0 1.0 23.2 98.6

Claims (7)

1. The catalyst for producing synthesis gas by steam reforming of synthetic hydrocarbon fuels, mainly methanol, characterized in that it is a catalytic structured unit with a gas distribution system, consisting of alternating corrugated and flat catalytically active tapes forming channels, the catalyst contains compounds as active components copper, zinc, chromium and aluminum in the following amounts, wt.%: copper oxide 5-15, chromium oxide 0.4-2.6, zinc oxide 3-16 and aluminum oxide 2-8, reinforced metalloporous carrier the rest is up to 100%. 2. The catalyst according to claim 1, characterized in that the value of the corrugation is approximately 2 mm 3. The catalyst of claim 1, characterized in that the reinforced metal-porous carrier can be made of stainless woven linen weave mesh, wire grade 12X18H9, fecal wire X23U5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY, stainless steel woven mesh With 120 grade of wire 12X18H9. 4. A method of preparing a catalyst for producing synthesis gas by steam conversion of synthetic hydrocarbon fuels, mainly methanol, by applying the active component to a carrier, characterized in that the catalyst is prepared by impregnating the carrier with a solution of copper, chromium, zinc and aluminum salts, drying and subsequent calcination at 400-450 ° C, a heat-resistant reinforced metal-porous carrier is used as a carrier, and a catalyst of the following composition is obtained, containing, wt%: copper oxide 5-15, chromium oxide 0.4-2.6, zinc oxide 3-16 and hydroxy 2-8 alumina fiber reinforced metal porous carrier balance to 100%, more catalytically active cut from the obtained fiber reinforced tape to form a catalyst, the catalyst, which is a structured catalyst unit with timing system, composed of alternating corrugated and flat strips catalytically active forming channels. 5. The method according to claim 4, characterized in that the reinforced metal-porous carrier can be made of stainless woven fabric of plain weave, wire grade 12X18H9, fecal wire X23U5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY, stainless steel woven mesh weave C 120 wire grade 12X18H9. 6. A method of producing synthesis gas by steam methanol conversion, characterized in that the process is carried out using a catalyst according to any one of claims 1 to 3 or prepared according to any one of claims 4 and 5. 7. The method according to claim 6, characterized in that the CO content in the reaction products is not more than 3%.