RU2665711C1 - Method for preparing catalyst for conversion of hydrocarbon fuels in synthesis gas and conversion process with application thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to catalysts, methods for their preparation and use in the conversion processes of various kinds of hydrocarbon fuels, such as natural gas, diesel fuel, liquefied petroleum gas (LPG), to synthesis gas. Method of preparing a catalyst for the conversion of hydrocarbon fuels to a synthesis gas is described by applying the active component to a carrier, a highly porous foam-cell material, foam-nickel or foam core, which after preliminary oxidative heat treatment has a heat resistance of 900–1,100 °C, thermal conductivity 3–5 W/(m⋅K), the porous structure of PPI 50–100, porosity of 90–95 %, specific surface of 0.05–0.10 m²/g, the total pore volume is 0.07–0.11 cm³/g, as the active component, magnesium oxide and nickel oxide are applied in an amount of not less than 1 % by weight, preferably 7–40 % by weight.

EFFECT: high conversion of various hydrocarbon fuels, mainly natural gas, liquefied petroleum fuels, diesel fuel to synthesis gas.

9 cl, 4 tbl, 12 ex

Description

The invention relates to catalysts, methods for their preparation and use in the conversion processes of various types of hydrocarbon fuels, such as natural gas, diesel fuel, liquefied petroleum gas (LPG), into synthesis gas for its further use in power plants based on fuel cells, as combustion-initiating fuel additives in internal combustion engines and other energy generating systems.

Highly porous cellular materials (HPMP) - a class of materials of a cellular structure having a low density combined with high specific strength, macroporous structure, low hydraulic resistance. At present, HPLM is used as filter elements, sound-absorbing panels, screens, structural elements of heat exchangers and heating devices, fire and explosion arresters, wind tunnels, and fuel cells. HPLC can be made of various base materials: nickel, copper, iron, nichrome, aluminum, fechral, chrome, stainless steels and alloys, bronzes, monel, cobalt, rhodium, platinum, gold, silver, carbon, porcelain, ceramic compositions (oxides carbides, nitrides, borides, silicides). VPNM have a unique open porous structure: porosity 80-95%, pore size 0.3-4 mm, permeability (0.8-5.0) * 10 ^-8 m ² , specific surface area of pores at the level of 500-3500 m ² / m ³ (JSC " EKAT "http://ekokataliz.ru/wp-content/uploads/2016/04/Penomaterialyi-proizvodstva-kompanii-E%60KAT-1.pdf), low volumetric heat capacity, thermal conductivity at the level of 3-5 W / (m⋅ K), heat resistance at the level of 1000-1100 ° С. All these qualities have led to the fact that recently there has been an increased interest in the practical use of materials based on HPLM. Nevertheless, the main direction of HPLM is currently associated with the use of ceramic materials. Ceramic materials have low thermal conductivity, brittleness, poor machinability as structural materials. HPLM-based metals are free from these drawbacks.

The present invention is devoted to the development of HPMP-based catalysts for the conversion of various types of hydrocarbon fuels, such as natural gas, diesel fuel, liquefied petroleum gas (LPG), into synthesis gas for its further use in fuel cell-based power plants, as an initiating combustion additive to fuel in internal combustion engines and other energy generating systems.

Patent RU 2323047, B01J 7/02 describes a method for manufacturing catalytic microchannel plates, which contain foam metals, metal felt, metal wool, as well as catalyst powder embedded in the pores of the metal carrier as a porous metal support. The number of channels is from 2 to 120 pieces per 1 cm of length and depends on the pore size in the metal, and the channel width and wall width between the channels should be at least 5 times larger than the pore size in the metal used. The result is microchannel plates consisting of a metal matrix and catalyst powder with submillimeter channels of a given size.

In the patent US 6890878, B01J 8/00 a method for the preparation of mixed catalysts based on 20% foams and 60% by volume of the catalytically active mass is proposed. After mixing, the catalyst is impregnated with phosphoric acid and is used for catalytic condensation of hydrocarbons.

US Pat. No. 4,863,712, B01J 35/04 discloses a hydrocarbon fuel reforming catalyst. The catalyst is prepared on the basis of ceramic foam, has an irregular structure with a porosity of 40-85% and an observed density of 0.7 g / cm. Ceramic foam has open pores and is available for impregnation with the active component.

Patent RU 2417840, B01J 5/10 describes a catalytic element of a regular structure, characterized in that it consists of two structurally integrated components, the first component is a carrier matrix made of one or more types of highly porous permeable cellular materials, in which a space for the second component. The second component is discrete granules of one or more types, which are fully or partially placed in the formed space inside the matrix. According to the applicants, the described catalytic element allows you to adjust the heat and mass transfer parameters of the processes by combining the catalytic components of one or different types; exclude losses from abrasion and entrainment of the used catalytic element. Structurally, the catalytic element can be made in the form of a matrix of HPLM, in the channels of which granules of a porous material are placed. Various combinations are possible when the matrix and granules are made of catalytically active or inert materials. The technological capabilities of the catalytic element make it possible to create spatial structures of a complex and diverse form from it. The matrix from HPLC can be prepared by galvanic molding, plastic deformation, stamping, welding, cutting, etc. A significant advantage of the catalyst element "VPNM + granules" is the ability to create catalytic reactors of any shape, as well as catalysts of variable composition and loading in accordance with the design requirements for the reactor. Significant disadvantages of the proposed technical solution is the complexity of the design, and its suitability only for exothermic reactions. The location of the catalyst granules inside the matrix channels actually in a more complex form repeats a conventional tubular reactor with all its problems associated with the occurrence of hot spots, unstable modes, the complexity of the distribution of gas flows, wall heat transfer coefficients, etc.

Thus, from the analysis we can conclude that HPLM can be a promising carrier for the subsequent preparation of heat-resistant catalysts. But in this case, an increase in the specific inner surface of the HPLM from ~ 0.05 m ² / g to 1.7-1.8 m ² / g is required, for example, by deposition of a porous substrate with subsequent application of active components to it.

Most industrial catalysts for the low-temperature conversion of hydrocarbon fuels are based on the use of nickel and chromium-alumina compounds as active components. These include industrial nickel-containing methanation catalysts: NIAP-18 (NiO - 15 wt.%, CaO - 8 wt.%, Al ₂ O ₃ - 74.4 wt.%), NIAP-12-05 (NiO - 48 wt.%, Cr ₂ O ₃ - 27 wt.%), NIAP-07-01 (NiO - 36 wt.%), NIAP-07-05 (NiO - 38 wt.%, Cr ₂ O ₃ - 12 wt.%). A significant nickel content and the presence of chromium provide the necessary level of activity and the service life of these catalysts, which was experimentally demonstrated in the reaction of diesel pre-reforming [V.A. Kirillov et al. Theor. basics Chem. Technologies. 2015.V. 49, No. 1. S. 32-43].

These catalysts are successfully used in fixed-bed reactors in traditional industrial processes. However, due to low thermal conductivity, fragility of materials, limitations on structural application, problems with the implementation of dynamic modes, significant hydraulic resistance, the use of catalysts in non-traditional areas, such as power plants based on fuel cells, the preparation of combustion-initiating additives to fuel in internal combustion engines and others power generating systems are significantly limited.

The closest analogue to this technical solution, partially eliminating these drawbacks, is the patent RU 2491118, B01J 23/40, B01J 35/04, which proposes a method of preparing a catalyst based on metal mesh carriers (stainless steel mesh, fechral, foam metals, nickel, monoliths from metal foil) having low hydrodynamic resistance, and Group VIII metals as an active component to produce synthesis gas from gaseous hydrocarbon feeds (for example, methane, natural gas or petroleum gas), not accompanied by intense sooting and increased formation of carbon dioxide. The sequence of technological operations in the preparation of the catalyst is as follows:

- heat treatment at a temperature of 500-600 ° C;

- the preparation of aqueous solutions of the complex (H ₂ PdCl ₄ , H ₂ PtCl ₄ , H ₃ RhCl ₆ ), or nickel oxalate;

- treatment of the carrier by immersion in the prepared solution at a temperature of 80-90 ° C for 5-10 minutes, the deposition of Nickel is carried out by an electrolytic method;

- air drying and activation in a stream of methane-air mixture at 200-800 ° C.

The prepared catalyst contains 0.1-10 wt. % metal of group VIII on the carrier, preferably 0.5-5 wt. %

It is indicated that the catalyst should be used in the partial oxidation of methane at temperatures of 800-950 ° C, contact time of 3000-10000 h ^-1 , the molar ratio of oxygen / methane 0.2-0.8, preferably 0.45-0.55. Under these conditions, the selectivity for carbon monoxide reached 97%, the methane conversion on the catalyst 5% Pd / grid was 91.5-83.1%, 1% Pt / grid was 72.4%, 5% Ni / fechral was 91.5%. The main disadvantages are the insignificant (actually geometric) specific surface area of the catalyst, its focus on conducting highly exothermic oxidation reactions of hydrocarbon fuels in the field of external diffusion, presumably low activity in carrying out endothermic reactions of the conversion of hydrocarbon fuels, and the use of mainly platinoids as active components.

The invention solves the problem of developing effective catalysts for the conversion of hydrocarbon fuels into synthesis gas by applying the active component to a carrier.

EFFECT: high conversion of various hydrocarbon fuels, mainly natural gas, liquefied hydrocarbon fuels, diesel fuel, into synthesis gas.

The problem is solved by the method of preparing a catalyst for the conversion of hydrocarbon fuels into synthesis gas by applying a substrate and an active component to a carrier, which is a highly porous foam-cellular material, foam nickel or foam-nickel, (HPLC), having a heat resistance of 900-1100 ° C, thermal conductivity of 3-5 W / (m⋅K), the porous structure of PPI 50-100, porosity 90-95%, specific surface area 0.05 m ² / g, total pore volume 0.07-0.11 cm ³ / g.

As the active component, magnesium oxide and nickel oxide are applied in an amount of at least 1 wt. %, preferably 7-40 wt. %

The HPMP heat treatment is carried out in an oxidizing medium at a temperature of 800-1100 ° C, as a result, the specific surface increases to 0.10 m ² / g.

The application of the active component is carried out by the method of repeated impregnation with solutions of salts of nitrate or magnesium acetate to the weight of magnesium oxide on the surface of the carrier 5-20 wt. % with subsequent stepwise heat treatment and the formation of a film of magnesium oxide uniformly covering the surface of highly porous foam-cellular material, with a thickness ensuring the absence of intra-diffusion braking and increasing the internal specific surface to 1.7-1.8 m ² / g, and subsequent repeated impregnation with solutions of nickel nitrate or nickel acetate with repeating successive drying, calcining operations to decompose the salt and, if necessary, recover.

Multiple impregnation with salts of nitrate or magnesium acetate, nickel nitrate or nickel acetate is carried out from a joint solution prepared in such a ratio that after the calcination procedure in air, the ratio of supported MgO / NiO is 1: 1-1: 1.5.

The activity of the catalyst can be controlled by the amount of magnesium oxide and / or nickel oxide deposited on the substrate, determined by the composition of the impregnating solutions, the amount of impregnation, and varying from 7 to 40 wt. %

The problem is also solved by the method of steam conversion of hydrocarbon fuels to synthesis gas using a catalyst prepared as described above, at a temperature above 300 ° C, preferably 600-1000 ° C.

The technical solution is based on the following technological operations for the preparation of catalysts.

1. The selection of media for the preparation of structured catalysts based on HPLM. When choosing carriers, it is necessary to use HPLC from foam nickel and foam-chromium having a heat resistance of 900-1100 ° C, thermal conductivity of 1-5 W / (m⋅K), a porous structure with PPI of 50-100, porosity of 90-95%, and specific surface area 0.05 m ² / g, total pore volume 0.07-0.11 cm ³ / g.

2. Heat treatment of the carrier. Heat treatment must be carried out in an oxidizing environment to a gain of 6-8 wt. %, at a temperature of 800-1100 ° C for 6-7 hours. Heat treatment provides a smoothing of chemical and structural inhomogeneities of the surface of the carrier, ensures the creation of a uniform oxide film on its surface that improves adhesion properties during subsequent deposition of the substrate and active catalyst components, an increase in surfaces up to 0.10 m ² / g.

3. Preparation of impregnating solutions based on magnesium nitrate and nickel nitrate.

4. Development of the surface of the carrier by applying magnesium oxide by repeatedly impregnating the carrier with an impregnating solution with intermediate heat treatment. The carrier must be kept in the impregnating solution for at least 30 minutes, then dried first at room temperature for ~ 24 hours, then in a muffle furnace at 120 ° C for 2 hours, followed by heat treatment from 200 ° C, increasing the temperature stepwise by 50 ° C to 550 ° C, and exposure at this temperature for two hours. The operation of impregnation with a solution is repeated several times until the specified weight gain of MgO, which can be 1-25 wt. % In this case, the specific surface of the carrier will increase to 1.7-1.8 m ² / g, the thickness of the layer of the secondary carrier of magnesium oxide will be 20-40 microns, which ensures the conversion reaction in the kinetic region.

5. Application of the active component of the catalyst by repeated impregnation of the carrier with solutions of nickel nitrate or nickel acetate, followed by routine drying, calcining for salt decomposition and, if necessary, reduction to metal. To carry out the procedure, the prepared HPLC – MgO carrier is placed in a solution of nickel nitrate / nickel acetate saturated at room temperature. After exposure to the solution, the sample is removed from the impregnating solution and then the heat treatment procedures are repeated as in paragraph 4. The operation of impregnation with solutions of nickel nitrate or nickel acetate should be repeated several times until the specified gain of NiO, which can be 1-40 wt. % The final heat treatment should be carried out at 650 ° C for 4 hours.

6. Operations 4 and 5 can be combined. In this case, the impregnating solutions must be prepared in the ratio MgO / NiO 1: 1-1: 1.5, depending on the required ratio of nickel and magnesium oxides in the prepared catalyst. By varying the compositions of the impregnating solutions or the amount of impregnation, it is possible to prepare catalysts of different composition, and therefore, different activity.

7. Before using the catalyst, it must be activated in a nitrogen-hydrogen mixture at a temperature of 420-450 ° C.

The invention is illustrated by the following examples.

Example 1

Use HPLC based on foam nickel with PPI = 60. The HPMP was subjected to heat treatment at a temperature of 900 ° C for 7 h. Next, magnesium oxide was deposited by repeatedly impregnating the support with an impregnating solution of magnesium acetate with intermediate heat treatment. The carrier was kept in an impregnating solution for 50 minutes, then dried first at room temperature for ~ 24 hours, then in a muffle furnace at 120 ° C for 2 hours, followed by heat treatment from 200 ° C, increasing the temperature stepwise by 50 ° C to 550 ° C, and holding at this temperature for 2 hours. The operation of impregnation with a solution was repeated several times until a weight gain of 20 wt. % MgO. Next, nickel acetate was impregnated. To carry out this procedure, the prepared MgO / HPLM support was placed in a solution of nickel acetate saturated at room temperature. After exposure to the solution for 1 h, the sample was removed from the impregnating solution and then dried first at room temperature for ~ 24 h, then in a muffle furnace at 120 ° С for 2 h, followed by heat treatment starting from 200 ° С, increasing the temperature stepwise 50 ° C to 550 ° C, and holding at this temperature for 2 hours. The operation of impregnation with solutions of nickel acetate was repeated several times to gain 13.3 wt. % NiO. The final heat treatment was carried out at 650 ° C for 4 hours

The composition of the catalyst: 13.3 wt. % NiO / 20 wt. % MgO / VLP.

Example 2

The catalyst was prepared analogously to example 1, HPLM was used from foamychrome with PPI = 80, heat treatment of HPLM was carried out at a temperature of 1000 ° C for 6 hours. An MgO impregnation solution was prepared from magnesium acetate. An impregnation solution for applying NiO was prepared from nickel nitrate.

The composition of the catalyst: 40 wt. % NiO / 20 wt. % MgO / VLP.

Example 3

The catalyst was prepared analogously to example 1, HPLM was used from foamychrome with PPI = 70, heat treatment of HPLM was carried out at a temperature of 1000 ° C for 6 hours. An impregnation solution for applying MgO was prepared from magnesium nitrate. An impregnation solution for applying NiO was prepared from nickel nitrate.

The composition of the catalyst: 12.3 wt. % NiO / 23.6 wt. % MgO / VLP.

Example 4

The catalyst was prepared analogously to example 1, HPLM was used from foam nickel with PPI = 60, heat treatment of HPLM was carried out at a temperature of 900 ° C for 6 hours. An impregnation solution for applying MgO was prepared from magnesium nitrate. An impregnation solution for applying NiO was prepared from nickel acetate.

The composition of the catalyst: 13.6 wt. % NiO / 18.2 wt. % MgO / VLP.

Example 5

Use HPLC from foam nickel with PPI = 60. The HPMP was subjected to heat treatment at a temperature of 900 ° C for 7 h. Next, magnesium oxide and nickel oxide were applied from an impregnating solution simultaneously containing magnesium and nickel acetates in a 1: 1 ratio. The carrier was kept in an impregnating solution for 50 minutes, then dried first at room temperature for ~ 24 hours, then in a muffle furnace at 120 ° C for 2 hours, followed by heat treatment from 200 ° C, increasing the temperature stepwise by 50 ° C to 550 ° C, and holding at this temperature for 2 hours. The operation of impregnation with a solution was repeated several times. The final heat treatment was carried out at 650 ° C for 4 hours

The composition of the catalyst: 7 wt. % NiO-7 wt. % MgO / VLP.

Example 6

The catalyst was prepared analogously to example 5. Use HPLM from penonychrome with PPI = 80. HPLC was subjected to heat treatment at a temperature of 1000 ° С for 7 h. The impregnating solution simultaneously contained magnesium nitrate and nickel acetate in a ratio of 1: 1.5.

The composition of the catalyst: 15 wt. % NiO-10 wt. % MgO / VLP.

Example 7

The catalyst was prepared analogously to example 5. The impregnation solution simultaneously contained magnesium acetate and nickel nitrate in a ratio of 1: 1.1.

The composition of the prepared catalyst: 11 wt. % NiO-10 wt. % MgO / VLP.

Example 8

The catalyst was prepared analogously to example 5. The impregnation solution simultaneously contained magnesium nitrate and nickel nitrate in a ratio of 1: 1.2.

The composition of the catalyst: 12 wt. % NiO-10 wt. % MgO / VLP.

For the catalysts prepared in this way, the specific surface area of the catalyst, determined by the low-temperature nitrogen adsorption method, was 1.7–1.8 m ² / g. The catalysts were made in the form of disks with a diameter of 8 to 120 mm and a thickness of 2-10 mm. The use of such catalytic disks makes it very easy to create a catalyst layer structure that provides an optimal activity profile, to regulate selectivity, and, accordingly, to obtain the required reactor productivity.

Example 9

The test results of the catalyst 7 wt. % NiO-7 wt. % MgO / HPLC (prepared according to example 5) in the steam reforming reaction of natural gas. Experimental conditions: atmospheric pressure, natural gas flow rate - 42.9 ml / min, water flow rate - 3.8 ml / h, Н ₂ O / С = 2, GHSV = 10200 h ^-1 , catalyst loading 0.7 cm ³ , mass 1.1 g, reactor diameter 8.5 mm.

Example 10

The test results of the catalyst 12 wt. % NiO-10 wt. % MgO / HPLM (prepared according to example 8) in the steam reforming reaction of natural gas. Experimental conditions: atmospheric pressure; natural gas consumption - 47.8 ml / min; water consumption - 4.3 ml / h; H ₂ O / C = 2; GHSV = 10,200 h ^-1 ; catalyst loading: mass — 0.8 g, volume — 0.78 cm ³ , catalyst in the form of a block of 5 identical disks (disk diameter 8.5 mm, disk thickness 3 mm.), inner diameter of the reactor 8.5 mm.

Example 11

The test results of the catalyst 40 wt. % NiO / 20 wt. % MgO / HPMP (prepared according to example 2) in the steam reforming reaction of liquefied petroleum gases (LPG). The composition of the input LPG brand PBA (vol.): Propane - 50%, butane - 50%. LHG flow rate 0.965 nm ³ / h, input molar ratio Н ₂ О / С = 0.70, GHSV = 6000 h ^-1 , catalyst loading 0.16 l. The catalyst is used as a set of disks with a diameter of 40 mm and a thickness of 6-8 mm in a heated cylindrical reactor.

Example 12

The test results of the catalyst 15 wt. % NiO / 10 wt. % MgO / HPLC (prepared according to example 6) in the reaction of steam reforming of diesel fuel. Experimental conditions: atmospheric pressure, ultrafine sulfur fuel, diesel consumption - 1.12 ml / h, water consumption - 3.88 ml / h, Н ₂ О / С = 3.2, GHSV = 6000 h ^-1 , catalyst loading 0.82 cm ³ , inner diameter of the reactor 8.5 mm.

In experiments, a flow meter measured the flow rate of dry conversion gases and chromatographically their composition. The conversion was determined based on the amount of carbon fed to the inlet of the reactor and the amount of carbon in the dry reaction products at the outlet of the reactor.

The above examples show the applicability of the developed catalysts based on highly porous foam-based materials HPLM for the conversion of various types of hydrocarbon fuels to produce synthesis gas for subsequent use in solving problems of hydrogen energy and creating environmentally friendly transport.

Claims (9)

1. A method of preparing a catalyst for the conversion of hydrocarbon fuels into synthesis gas by applying the active component to a carrier, characterized in that the carrier is a highly porous foam-cellular material, foam nickel or foam foam, which, after preliminary oxidative heat treatment, has a heat resistance of 900-1100 ° C, thermal conductivity 3-5 W / (m⋅K), porous structure PPI 50-100, porosity 90-95%, specific surface 0.05-0.10 m ² / g, total pore volume 0.07-0.11 cm ³ / g. 2. The method according to p. 1 characterized in that the source medium is subjected to preliminary heat treatment in an oxidizing environment to a gain of 6-8 wt.% At a temperature of 800-1100 ° C for 6-7 hours 3. The method according to p. 1, characterized in that the active component is applied magnesium oxide and nickel oxide in an amount of not less than 1 wt.%, Preferably 7-40 wt.%. 4. The method according to p. 1, characterized in that the heat treatment of the highly porous foam-cellular material is carried out in an oxidizing environment at a temperature of 800-1100 ° C. 5. The method according to p. 1, characterized in that the application of the active component is carried out by repeatedly impregnating with solutions of salts of nitrate or magnesium acetate to add magnesium oxide on the surface of the carrier 5-20 wt.% With subsequent stepwise heat treatment and the formation of a film of magnesium oxide uniformly coating surface of highly porous foam-cellular material, with a thickness that ensures the absence of intra-diffusion braking and increases the internal specific surface to 1.7-1.8 m ² / g, and subsequent multiple impregnation of ra solutions of Nickel nitrate or Nickel acetate with the repetition of successive drying, calcining for decomposition of salt and, if necessary, recovery. 6. The method according to p. 5, characterized in that the multiple impregnation with salts of magnesium nitrate or acetate, nickel nitrate or nickel acetate is carried out from a joint solution prepared in such a ratio that after the calcination procedure in air, the applied MgO / NiO ratio is 1: 1 - 1: 1.5. 7. The method according to p. 1, characterized in that the activity of the catalyst is controlled by the amount of magnesium oxide and / or nickel oxide deposited on the substrate, determined by the composition of the impregnating solutions, the amount of impregnation and varying from 7 to 40 wt.%. 8. A method of conducting a steam conversion of hydrocarbon fuels into synthesis gas, characterized in that the catalyst prepared according to paragraphs is used as a catalyst. 1-7. 9. The method according to p. 8, characterized in that the conversion of hydrocarbon fuels to synthesis gas is carried out at a temperature above 300 ° C, preferably 600-1000 ° C.