RU2356628C1 - Catalyst, method of making it and method of obtaining synthetic gas from biodiesel fuel - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to catalysts for autothermal conversion of biodiesel to obtain synthetic gas. Synthetic gas can be used in chemical production, for combustion in catalytic heating plants and in hydrogen power generation. The proposed catalyst for obtaining synthetic gas contains active components in form of cobalt oxide, manganese oxide and barium oxide, and a heat resistant reinforced porous metallic carrier. The catalyst is prepared by impregnating the carrier with a solution of barium and manganese salts, drying and then heat treatment. The carrier is then impregnated with a solution of cobalt salt with subsequent drying and calcination. Described also is a method of obtaining synthetic gas through autothermal conversion of biodiesel fuel, using the above described catalyst.

EFFECT: catalyst is characterised by high heat conductivity and is highly active in producing synthetic gas, resistant to coke formation and deactivation by sulphur compounds, contained in the biodiesel fuel.

6 cl, 1 tbl, 4 ex

Description

The invention relates to catalysts for autothermal conversion of biodiesel 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), for the reduction of nitrogen oxides on board a vehicle.

Analysis of patent data [US 6969411, B01J 12/00, 04/07/2005; US 6949683, B01J 23/63, 06/26/03; US 6835354, C01B 3/38, 06/13/2002; US 6797244, B01J 12/00, 09/28/2004; US6620389, B01F 3/02, 09/16/2003; US 6436363, B01J 23/42, 08/20/2002; US 6409974, A61B 17/04, 06/25/2002] shows that the main direction of development of catalysts for autothermal conversion of hydrocarbon fuels is associated with supported platinum group catalysts, such as Rh, Pt, Pd, metal oxides with perovskite structure (LaCrO ₃ , LaMnO ₃ , LaFeO ₃ , LaCoO ₃ , LaNiO ₃ ). To increase sulfur resistance and activity, the catalysts were additionally doped with gadolinium and cerium oxide.

In the works of [JMMawdsley, M. Ferrandon, C. Rossignol, J. Ralph, L. Miller, J. Kopasz, T. Krause. "Catalysts for autothermal reforming." In ANL FY Progress Report "Hydrogen, Fuel Cells, and Infrastructure Technologies" 2003. T. Krause, M. Ferrandon, J. Mawdsley, J. Ralph. "Catalysts for autothermal reforming." In the ANL FY Progress Report "DOE Hydrogen Program" 2004] on the reaction of the autothermal conversion of gasoline, it was shown that Rh and Rh-Pt with the addition of Gd and CeO ₂ yield 8.7 and 9.3 moles of hydrogen per mole of gasoline at temperatures of 700-750 ° C. Under the same conditions, platinum catalysts yield only 2.5 moles of hydrogen. The methane yield is 0.4 mol per mole of gasoline. The addition of sulfur compounds at a level of 30-50 ppm significantly reduces the activity of the catalysts. However, with an increase in the reaction temperature to 800 ° C, the effect of sulfur decreases significantly, especially for Rh / Al ₂ O ₃ catalysts. In these works, a significant effect of the carrier on the hydrogen yield was also noted. So, when using Rh / Al ₂ О ₃ as a catalyst, the hydrogen yield is 12 moles per mole of gasoline, on the Rh / CeO ₂ catalyst this value is 7 moles per mole of gasoline, for perovskite-based catalysts, the yield is 8 moles per mole of gasoline, respectively .

Closest to our proposed catalyst is a catalyst for producing synthesis gas by autothermal conversion of diesel fuel [US 6969411, B01J 12/00, 04/07/2005]. The catalyst is a monolithic block of metal foam, divided into two catalytic zones. At the entrance, there is a metal foam with an alumina substrate, with active components made of calcium oxide, iron oxide and / or impregnated with Pt, Pd or Rh. Additives of precious metals comprise from 0.1 to 1.0% by weight of the catalyst. At the exit: a metal foam with a substrate of aluminum oxide, coated with active Ni components or noble metals. The process is carried out at an inlet temperature of the mixture of 250 ° C.

The disadvantage of this catalyst is that the structure of the carrier of metal foam is irregular in nature with a large variation in pore size. It has high porosity and closed pores, which reduces thermal conductivity and specific surface, as well as mechanical characteristics. It has insufficient resistance to coke formation. In addition, it is difficult to fabricate samples from some heat-resistant alloys using this technology.

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

The catalyst should have the following properties:

- high thermal stability and scale resistance;

- resistance to coke formation;

- resistance to deactivation by sulfur compounds contained in biodiesel;

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

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

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

As a carrier, a heat-resistant reinforced metal-porous carrier made of mesh heat-resistant steels is used, on which active components are applied. This technology provides mechanical strength, thermal conductivity, regularity and uniformity of structure. 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 autothermal conversion of biodiesel, which is a structured monolithic catalyst. The catalyst contains manganese oxide, barium oxide and cobalt oxide deposited on a heat-resistant reinforced metal-porous carrier, which can be used as a reinforced fechral network, with the content of components in the catalyst, wt.%: Cobalt oxide 7-12%, manganese oxide and barium oxide 10 -15% (Ba / Mn ratio = 4-5 / 5-4, optimally 5/4), heat-resistant reinforced metal-porous carrier - the rest is up to 100%.

According to transmission electron microscopy, in the catalytic layer separated from the reinforcing mesh, the fraction of particles in the form of large-block agglomerates with a size of several microns and primary particle sizes of 100-200 nm predominates. The sizes of separately encountered particles reach 1 μm. X-ray spectra show that these particles are dominated by elements: Fe, Co, and Mn, the relative contents of which are not the same for different particles. In addition, impurity elements are found for particles of this type: Al, Cr, Ti, Mg, Si, K, and also S, Cl. It can be assumed that the observed particles could be formed as a result of the interaction of supported components (Mn, Co) with the surface of the reinforcing carrier.

The carrier can be made of X23U5T material having the following chemical composition, wt.%: C - 0.05, Si - 0.5, Mn - 0.3, Cr - 22-24, Ni - 0.6, Ti - 0.2-0.5, S - 0.015, P - 0.030, Al - 5.0-5.8, Fe - the rest, and 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 of barium, manganese and cobalt salts in water.

3. Precipitation of the active component. The prepared carrier is impregnated several times in an aqueous solution of salts with a given ratio of active components until the mass of the catalyst increases by 10-15 wt.%. After each impregnation process, the sample is heated to 600-650 ° 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.

7. Preparation of catalysts of regular structure.

Barium and manganese salts are applied to a monolithic metal-porous catalyst based on a fechral mesh (77-79 wt.%) At a ratio of Ba / Mn = 5/4, until the mass of the catalyst increases by 10-15 wt.%, And calcined at 600-650 ° C. The reinforced carrier thus prepared is impregnated with an aqueous solution of cobalt salt (7-12 wt.%) And heat treatment is carried out at 600-650 ° C.

The heat-resistant metal-porous carrier can be made of fecal wire X23U5T, Megapir 200, EurofehralGST, EurofehralGS 23-5, EurofehralGS SY.

The block catalyst was a monolith formed from flat and corrugated gas permeable catalyst tapes. 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 occurrence of high-intensity catalytic processes, which is the autothermal conversion of biodiesel at high temperatures. The dimensions of the block catalyst depend on the process conditions.

The problem is also solved by the method of producing synthesis gas of autothermal conversion of biodiesel at a temperature of 700-950 ° C in the presence of the above catalyst.

Distinctive features of the proposed catalyst are:

1. The composition of the catalyst, containing wt.%: Cobalt oxide - 7-12%, manganese oxide and barium oxide - 10-15% (Ba / Mn = 4-5 / 5-4, optimally 5/4), heat-resistant reinforced metal-porous carrier - the rest is up to 100%.

The introduction of barium oxide into the catalyst contributes to the stability of the catalyst to carbonization, increase the duration of stable operation; the use of a heat-resistant 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.

2. Reinforced heat-resistant metal-porous carrier, for example, made of fecal wire X23U5T.

The catalyst is resistant to coke formation, provides a H ₂ / CO ratio in autothermal conversion products of 2-3 and provides a long service life without significant deactivation by sulfur compounds contained in biodiesel.

Moreover, during the process of autothermal conversion of biodiesel under optimal conditions: О ₂ /С = 0.5-0.65, Н ₂ О / С = 0.9-1.3, contact time 0.3-0.4 sec, temperature of the mixture at the reactor inlet 180-210 ° С , the reaction products contain: Н ₂ = 26.2%, CH ₄ = 0.5%, CO ₂ = 13.6%, СО = 10.1%, N ₂ = 49.6% (concentration in the dry mixture is given); the synthesis gas yield is 1.8-2.2 nl per gram of biodiesel.

The invention is illustrated by the following examples.

Example 1

The catalyst is prepared as follows. An aqueous solution of barium and manganese salts with a ratio of Ba / Mn = 5/4 is applied to a heat-resistant reinforced metal-porous monolithic carrier based on a fechral mesh (79 wt.%), Until the mass of the catalyst increases by 12 wt.%, And calcined at 600- 650 ° C. Then, the sample thus prepared is impregnated with an aqueous solution of cobalt salt, until the mass of the catalyst increases by 9 wt.%, And heat treatment is carried out at 600-650 ° C.

The catalyst in the form of a structured monolithic block is tested in the reaction of autothermal conversion of biodiesel. The costs of the reagents, the yield of reaction products of H ₂ and CO in a dry mixture, the temperature profile of the catalyst are shown in the table.

Example 2. Similar to example 1. The difference is that an aqueous solution of barium and manganese salts with a ratio of Ba / Mn = 5/4 is applied to a heat-resistant reinforced metal-porous monolithic support based on a fechral mesh (78 wt.%), Until the catalyst mass increase by 10 wt.%, and calcine it at 600-650 ° C. Then the sample thus prepared is impregnated with an aqueous solution of cobalt salt, until the mass of the catalyst increases by 12 wt.% And heat treatment is carried out at 600-650 ° C.

The catalyst in the form of a structured monolithic block is tested in the reaction of autothermal conversion of biodiesel. The costs of the reagents, the yield of reaction products of H ₂ and CO in a dry mixture, the temperature profile of the catalyst are shown in the table.

Example 3. Similar to example 2. The difference is that an aqueous solution of barium and manganese salts with a ratio of Ba / Mn = 5/4 is applied to a heat-resistant reinforced metal-porous monolithic support based on fechral mesh (78 wt.%), Until the mass of the catalyst will increase by 15 wt.%, and calcined at 600-650 ° C. Then, the sample thus prepared is impregnated with an aqueous solution of cobalt salt, until the mass of the catalyst increases by 7 wt.%, And heat treatment is carried out at 600-650 ° C.

The catalyst in the form of a structured monolithic block is tested in the reaction of autothermal conversion of biodiesel. The costs of the reagents, the yield of reaction products of H ₂ and CO in a dry mixture, the temperature profile of the catalyst are shown in the table.

Example 4. Similar to example 1. The difference is that an aqueous solution of barium and manganese salts with a ratio of Ba / Mn = 5/4 is applied to a heat-resistant reinforced metal-porous monolithic support based on a fechral mesh (78 wt.%), Until the mass of the catalyst will increase by 15 wt.%, and calcined at 600-650 ° C. Then, the sample thus prepared is impregnated with an aqueous solution of cobalt salt, until the mass of the catalyst increases by 7 wt.%, And heat treatment is carried out at 600-650 ° C.

The catalyst in the form of a structured monolithic block is tested in the reaction of autothermal conversion of biodiesel. The costs of the reagents, the yield of reaction products of H ₂ and CO in a dry mixture, the temperature profile of the catalyst are shown in the table.

As can be seen from the above data, the proposed catalyst allows the process of autothermal conversion of biodiesel to produce synthesis gas with high activity without coke formation.

Claims (6)

1. The catalyst for producing synthesis gas by autothermal conversion of biodiesel, including a metal-porous carrier and metal oxides, characterized in that it contains cobalt oxide, manganese oxide and barium oxide as active components, and it contains a heat-resistant reinforced metal-porous carrier as a carrier. 2. The catalyst according to claim 1, characterized in that it contains these components in the following amounts, for example, wt.%: Cobalt oxide - 7-12%, manganese oxide, barium oxide - 10-15%, with a ratio of Ba / Mn = 5 ÷ 4/4 ÷ 5, heat-resistant reinforced metal-porous carrier - the rest is up to 100%. 3. The catalyst according to claim 1 or 2, characterized in that the heat-resistant reinforced metal-porous carrier can be made of X23U5T fechral wire having the following chemical composition, wt.%: C - 0.05, Si - 0.5, Mn - 0 , 3, Cr - 22-24, Ni - 0.6, Ti - 0.2-0.5, S - 0.015, P - 0.030, Al - 5.0-5.8, Fe - the rest. 4. A method of preparing a catalyst for producing synthesis gas by autothermal conversion of biodiesel by applying the active component to a carrier, characterized in that the catalyst is prepared by impregnating the carrier with a solution of barium and manganese salts with a ratio of Ba / Mn = 5 ÷ 4/4 ÷ 5, drying and subsequent calcination at 600-650 ° C, then impregnated with a solution of cobalt salt, followed by drying and calcination at 600-650 ° C, a heat-resistant reinforced metal-porous carrier is used as a carrier. 5. The method according to claim 4, characterized in that the heat-resistant reinforced metal-porous carrier can be made of fechral wire having the following chemical composition, wt.%: C - 0.05, Si - 0.5, Mn - 0.3, Cr - 22-24, Ni - 0.6, Ti - 0.2-0.5, S - 0.015, P - 0.030, Al - 5.0-5.8, Fe - the rest. 6. A method of producing synthesis gas by autothermal conversion of biodiesel, 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.