TW201902818A - Process for carbon dioxide hydrogenation in the presence of an iridium and/or rhodium catalyst - Google Patents

Abstract

The invention relates to a process for carbon dioxide hydrogenation, which comprises reacting carbon dioxide with hydrogen in the presence of a catalyst including an iridium- and/or rhodium- containing active composition.

Description

Method for hydrogenating carbon dioxide in the presence of rhodium and/or rhodium catalyst

The present invention relates to a process for hydrogenating carbon dioxide comprising reacting carbon dioxide with hydrogen in the presence of a catalyst comprising a rhodium-containing and/or rhodium-containing active composition.

Recombination of hydrogen and carbon dioxide into carbon monoxide, also known as carbon dioxide hydrogenation or reverse water-gas shift (RWGS), is of great economic benefit as these methods provide the option of preparing synthesis gas as an important base chemical. Scheme in which carbon dioxide is used as a starting material. Therefore, it will be possible to combine the carbon dioxide obtained as waste in a large number of processes by a chemical route. This makes it possible to reduce the emission of carbon dioxide into the atmosphere.

In addition to the reverse water gas shift reaction, other methods of environmentally friendly use of carbon dioxide, such as methanation and dry recombination, are known. JP 3328847 B2 describes the use of a rhodium catalyst for methanation, that is, hydrogenation of carbon dioxide with hydrogen at a temperature of from 200 ° C to 550 ° C to obtain methane. WO 2015/091310 A1 discloses the use of a rhodium catalyst for the dry recombination of a mixture of hydrocarbons and carbon dioxide to obtain a synthesis gas.

It should be understood that the synthesis gas means a mixed gas containing hydrogen and carbon monoxide and which can be used as a base chemical in various industrial processes. The synthesis gas has a different ratio of hydrogen to carbon monoxide depending on its use.

Hydrogen is still commercially produced by steam reforming processes. Although these methods have the inherent price advantage reflected in the cost of hydrogen, the production of hydrogen is coupled with the high emissions of carbon dioxide.

In Germany, CO ₂ emissions in 2010 were approximately 960 million tons of CO ₂ equivalents, of which the chemical contribution was about 5%. From the ecological and environmental point of view, in the chemical industry, by changing the raw material base, low CO ₂ production technology, optimizing energy demand and using program-related CO ₂ to obtain a large amount of basic chemicals, there is a large reduction in CO ₂ emissions. attract. Suitable base chemicals are, for example, hydrogen and synthesis gases. The latter constitutes the ideal interface for the availability of petrochemical processes for the production of products such as methanol, dimethyl ether or Fischer-Tropsch. The current global demand for hydrogen and syngas is 50 million tons/year and 220 million tons/year.

For the production of methanol by hydrogenation of carbon dioxide to carbon monoxide, Graciani et al. proposed a Cu/CeOx catalyst (J. Graciani, K. Mudiyanselage, F. Xu, AE Baber, J. Evans, SD Senanayake, DJ Stacchiola, P. Liu, J). Hrbek, J. Fernandez Sanz, JA Rodriguez, Science 345 (2014) 546-550) and Bansode et al. proposed a Cu/ZnO/Al ₂ O ₃ catalyst (A. Bansode, A. Urakawa, J. Catal. 309 (2014) ) 66-70). In addition to Cu-based catalysts, WO 2015/135968 discloses catalysts based on mixed Ni, Co, Zn, Fe oxides.

Further, a noble metal-containing catalyst for hydrogenating carbon dioxide to carbon monoxide is described in US 8,961,829 B2. A catalyst is disclosed in which platinum has been deposited on cerium oxide, manganese oxide and/or magnesium oxide. The example specifies a Pt loading of 0.3% by weight.

US 2011/0105630 discloses platinum or palladium based catalysts for the hydrogenation of carbon dioxide to carbon monoxide. Possible carrier materials described are alumina, magnesia, ceria, titania, optionally sulfated zirconium dioxide, tungsten zirconium oxide, aluminum trifluoride, fluorided alumina, bentonite, zeolite, carbon-based support, Molecular sieves and combinations thereof. A preferred loading is specified to be from 10% by weight to 20% by weight.

In addition to the supported catalysts mentioned, the prior art also describes unsupported catalysts.

WO 2013/135710 discloses the hydrogenation of carbon dioxide to carbon monoxide in a shell and tube reactor. The catalyst disclosed is a hexaaluminate having the formula: LO _x (M _(y/z) Al _(2-y/z) O ₃ ) _z , wherein L = Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, Sn, Pb, Mn, In, Tl, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and/or Lu and M= Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Zn, Cu, Ag and/or Au. The mode of preparation of such unsupported hexaaluminate catalysts comprises a multi-stage process comprising stages of precipitation, filtration, washing, drying, shaping and calcination. An example of hydrogenation of carbon dioxide is not disclosed.

WO 2015/135968 discloses a process for producing a catalyst for the hydrogenation of high temperature carbon dioxide to carbon monoxide. The disclosed catalyst comprises at least one crystalline material comprising bismuth and aluminum and having the following typical characteristics: it has at least one of the following structures consisting of cubic garnet structure, orthorhombic perovskite structure, A hexagonal perovskite structure and/or a monoclinic perovskite structure (ie, Y ₄ AI ₂ O ₉ ), wherein the catalyst comprises Cu, Fe, Co, Zn, and/or Ni. The loading of the cerium-containing material is specified to be 0.1 mol% to 10 mol%. The examples show good performance in hydrogenation of carbon dioxide and also low carbon deposition on the catalyst. Experiments were performed at GHSV of 30 000 h ^-1 and 40 000 h ^-1 . The mode of preparation of such catalysts comprises a multi-stage process comprising stages of precipitation, filtration, drying, pre-calcination, shaping and post-calcination.

One of the objects of the present invention is to provide a catalyst for hydrogenating carbon dioxide which has high activity and stability, that is, good resistance to coke accumulation. In addition, the tendency to methanation should be lower.

Another goal is that the catalyst can be produced at low cost, meaning that it is possible to select a production mode that includes the minimum number of process steps. The supported catalyst can be produced by means of a process step of impregnation, drying, calcination, wherein the recommended duration for impregnation on a laboratory scale is typically 1/2 hour. Unsupported catalysts require procedures for precipitation, filtration, washing, drying/calcination, shaping, and (post) calcination, with a recommended duration of precipitation on a laboratory scale of half a working day. It is therefore an object to provide a supported catalyst for the hydrogenation of carbon dioxide which is as effective as the performance of the unsupported catalyst from the prior art.

In addition, the active metal loading should be as low as possible in order to be efficient and resource efficient.

Another object of the process of the invention is also suitable for the hydrogenation of carbon dioxide to carbon monoxide in the presence of a hydrocarbon, especially methane, meaning that the methane present in the reactant gas mixture is recombined.

Another object of the present invention is to identify catalysts having specific activities which are capable of converting a reactant gas mixture into a composition close to the thermodynamic prediction equilibrium even at high loadings (especially greater than 10 000 h ^-1 ). Catalysts with specific activities allow the reactor to be of a smaller size and thus keep the capital cost of this equipment component small.

"High temperature method" is understood to mean a method at a temperature of > 600 ° C, especially > 600 ° C and < 1400 ° C.

All percentages by weight referred to hereinafter are for the total weight of the catalyst comprising the support material.

The present invention relates to a process for hydrogenating carbon dioxide comprising reacting carbon dioxide with hydrogen in the presence of a catalyst, wherein the catalyst has a support material and an active composition, wherein the support materials used are Ce, La, Zr An oxide of Al, Ti, Ca, Si or Mg, SiC, MgAl spinel, Sr aluminate, La, Ba or Sr hexaaluminate, and/or mixtures thereof, and the active composition comprises at least And/or hydrazine as an active component, wherein the content of rhenium (calculated as metal) relative to the total weight of the catalyst is in the range of 0.005 wt% to 2 wt%, and the content of rhodium relative to the total weight of the catalyst (calculated as metal) in the range of 0.005 wt% to < 1 wt%, and when contacted with the active composition, the temperature of the reactant gases carbon dioxide and hydrogen is in the range of 600 ° C to 1300 ° C.

Preferably, carbon dioxide is reacted with hydrogen in the presence of a catalyst to obtain carbon monoxide and water.

The content of cerium is preferably in the range of 0.005 wt% to 0.75 wt%, more preferably 0.01 wt% to 0.75 wt%, especially 0.025% by weight to 0.75 wt%, based on the total weight of the catalyst. The content of cerium is preferably 0.005 wt% to 1.5 wt%, more preferably 0.01 wt% to 1 wt%, still more preferably 0.01 wt% to 1 wt%, still more preferably 0.01 wt% to 0.75 wt%, based on the total weight of the catalyst. In particular, it is in the range of 0.025% by weight to 0.75% by weight. All mixtures of bismuth and strontium known to those skilled in the art are conceivable. Especially priority is given to 铱.

The total content of cerium and lanthanum in the mixture is preferably from 0.005 wt% to 2 wt%, preferably from 0.005 wt% to 1.5 wt%, more preferably from 0.01 wt% to 1 wt%, more preferably, based on the total weight of the catalyst. From 0.01% by weight to <1% by weight, more preferably from 0.01% by weight to 0.75% by weight, especially from 0.025% by weight to 0.75% by weight.

Preferred support materials are oxides, aluminates and carbides. For example, oxides which should be mentioned are oxides of Ce, La, Zr, Al, Ti, Ca, Si and Mg and mixtures thereof, the carbides which should be mentioned are SiC and the aluminate to be mentioned is Spinel (especially MgAl spinel), Sr aluminate, and hexaaluminate of La, Ba and Sr. The following support materials are preferred: oxides of Ce, La, Zr and Al, Zr hydroxide doped with La and Ce, Al ₂ O ₃ (δ-θ), SiC, Y on ZrO ₂ in Ce on the _{2 ZrO, Ca-Si-ZrO} 2, 35% MgO 65% Al 2 O 3, 80% MgO 20% Al 2 O 3, 37% CaO 63% Al 2 O 3, ZrO 2 ( monoclinic Crystal), ZrO ₂ (tetragonal), 44.6% CaO 54.9% ZnO, TiO ₂ , MgO, SrAl ₂ O ₄ , BaAl ₂ O ₄ , La ₂ Zr ₂ O ₇ . The content of the doping element is advantageously in the range from 0% by weight to 5% by weight, in particular from 1% by weight to 3% by weight, relative to the support material.

Particularly preferred support materials are zirconium dioxide, titanium dioxide and aluminates, especially zirconium dioxide.

In a preferred embodiment of the catalyst used according to the invention, the active composition comprising zirconium dioxide has > 5 m ² /g, preferably > 20 m ² /g, more preferably > 50 m ² /g and especially > 80 m ² /g specific surface area. The specific surface area of the catalyst was determined by gas adsorption (ISO 9277:1995) by the BET method.

The presence of rhodium and/or rhodium in a finely divided form on a support, in particular a zirconium dioxide support, is particularly advantageous since this achieves a high catalytic activity at low levels of Ir and/or Rh. Advantageously, the size of the cerium-containing and/or cerium-containing particles is < 50 nm, preferably < 30 nm, more preferably < 20 nm and more preferably < 10 nm. For example, the size of the cerium-containing and/or cerium-containing particles is in the range of 1 nm to 100 nm, preferably in the range of 5 nm to 50 nm.

More preferably, hydrazine and/or hydrazine are present in a homogeneous form on the carrier or in the active composition. More preferably, the ruthenium and/or osmium is present in the carrier or in the active composition in a homogeneous and finely divided form.

In a preferred embodiment, the catalysts used in accordance with the invention are typically characterized in that Ir and/or Rh are present on the support, advantageously on the support comprising zirconium dioxide, and this has been doped with other elements. For doping of the carrier, it is preferred to select elements from the following: the rare earths of the periodic table (ie, from Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Groups of Tm, Yb, and Lu), Group IIa (that is, from the group of Mg, Ca, Sr, Ba), Group IVa (that is, from the group of Si), Group IVb (that is, from the group of Ti, Hf), Group Vb (i.e., from the group of V, Nb, Ta) or an oxide thereof.

If the catalyst comprises one or more doping elements in addition to cerium and/or cerium and, as the case may be, zirconia, the weight ratio of doping elements (especially from rare earth doping elements) based on the total weight of the catalyst It is in the range of 0.01% by weight to 80% by weight, preferably in the range of 0.1% by weight to 50% by weight, and particularly preferably in the range of 1.0% by weight to 30% by weight.

Advantageously, the catalyst used in accordance with the invention is typically characterized by the addition of rhenium and/or rhodium and a support material (advantageously zirconium dioxide) comprising rhodium as another doping element, wherein rhenium is in oxidized form. Preferably, the cerium oxide content is in the range of 0.01% by weight to 80% by weight, preferably 0.1% by weight to 50% by weight and more preferably 1.0% by weight to 3% by weight based on the total weight of the catalyst.

In another and preferred embodiment, the catalysts used in accordance with the invention are typically characterized in that they comprise, in addition to rhodium and/or rhodium and a support material (advantageously zirconium dioxide), one or more additional species from the rare earth group, Two elements are preferred as doping elements. Preferably, the doping element content is in the range of 0.01% by weight to 80% by weight, preferably 0.1% by weight to 50% by weight, and more preferably 1.0% by weight to 30% by weight based on the total weight of the catalyst. More preferably, lanthanum (La) and lanthanum (Ce) are used as doping elements.

Particularly preferred catalysts for use in accordance with the invention are those comprising Ir/ZrO ₂ and/or Rh/ZrO ₂ active compositions, wherein the zirconium dioxide has antimony doping and/or antimony and/or antimony doping.

In other configurations, the active compositions used in accordance with the present invention for use in the process of the present invention also include promoters and/or other metal cations that further enhance catalyst efficiency.

Other doping elements may include: noble metal-containing promoters, non-noble metal-containing promoters, and other metal cations:

In a preferred embodiment, the catalyst or active composition used according to the invention comprises at least one promoter comprising a noble metal from the group Pt, Pd, Ru, Au, wherein the promotion of precious metals is relative to the total weight of the catalyst The proportion of the agent is in the range of 0.01% by weight to 5% by weight, and more preferably in the range of 0.1% by weight to 3% by weight.

In another preferred embodiment, the catalyst used in accordance with the present invention comprises at least one non-noble metal promoter comprising a group of Ni, Co, Fe, Mn, Mo, W, wherein the total weight of the catalyst is non-containing The proportion of the promoter of the noble metal is in the range of 0.1% by weight to 50% by weight, preferably in the range of 0.5% by weight to 30% by weight, and more preferably in the range of 1% by weight to 20% by weight.

In another embodiment, the catalyst used in accordance with the invention also comprises a portion of other metal cations, preferably selected from the group consisting of Mg, Ca, Sr, Ba, Ga, Be, Cr, Mn, with particular preference to Ca and/or Mg.

The components present in the catalyst used according to the invention, ie the noble metals, alkaline earth metals, doping elements, promoters and support materials mentioned, may be in elemental and/or oxidized form.

It is to be understood that the invention is not to be limited to the scope of the combinations and values specified in the present specification; in fact, the components may be conceivable and practically possible in other combinations within the scope of the main patent application.

The method for applying the active component to the carrier material can be any method known to those skilled in the art of catalyst production (see, for example, Haber et al. "Manual of methods and procedures for catalyst characterization", Pure & Appl Chem., Vol. 67, No. 8/9, pp. 1257-1306, 1995). Examples include impregnation with impregnation solution, impregnation of pore volume, spray coating of the impregnation solution, washcoating, and precipitation. The shaped bodies can be produced from powdered starting materials by methods known to those skilled in the art, such as ingot, agglomerate or extrusion, especially as in Handbook of Heterogeneous Catalysis, vol. 1, VCH Verlagsgesellschaft Weinheim, 1997, p. 414. Described in -417.

The ruthenium-containing and/or ruthenium-containing active composition can also be applied to a carrier, monolith or honeycomb. The monolith or honeycomb can be composed of metal or ceramic. The shaping of the active composition or the application of the active composition to the support or carrier body is of great industrial importance for the field of use of the catalysts used according to the invention. Depending on the particle size and reactor packing, the shape of the particles affects the pressure drop caused by the fixed catalyst bed. Molding can be carried out by any method known to the skilled artisan in the field of catalyst production (see for example Deutschmann, O., Knozinger, H., Kochloefl, K. and Turek, T. 2011. Heterogeneous Catalysis and Solid Catalysts, 2. Development and Types of Solid Catalysts. Ullmann's Encyclopedia of Industrial Chemistry).

The invention further relates to a catalytic process for the hydrogenation of carbon dioxide to carbon monoxide, i.e., for the production of a synthesis gas, wherein: (i) contacting a gas comprising CO ₂ and H ₂ -containing reactants with a rhodium and/or rhodium catalyst, Ii) the pressure of the reactant gas in the range of 1 bar _abs to 100 bar _abs when in contact with the catalyst, and the temperature of the reactant gas in the range of 20 ° C to 1400 ° C when in contact with the catalyst, Iii) The value of GHSV of the method is in the range of 1000 h ^-1 to 1 000 000 h ^-1 , and the H ₂ /CO ratio of the synthetic gas produced in (iv) is in the range of 0.1 to 10, more preferably in the range of 1 to 4. It is particularly preferably within the range of 1.5 to 3.

Advantageously, the molar ratio of reactant gas H ₂ /CO _{2 is in} the range from 0.1 to 20, preferably from 0.3 to 10, more preferably from 1 to 7, especially from 2 to 5.

Advantageously, the reactant gas has the composition that the molar ratio of CO ₂ is advantageously in the range of from 1% to 90%, preferably from 3% to 75%, more preferably from 10% to 60%, especially from 20% to 50%. The molar ratio of H ₂ is advantageously in the range of from 1% to 99%, preferably from 10% to 90%, more preferably from 20% to 85%, especially from 40% to 80%. The ratio of CH ₄ moie is advantageously in the range of 0% to 30%, preferably 0% to 20%, more preferably 0% to 15%, still more preferably 0 to 10%, especially 0% to 5%. The molar ratio of N ₂ is advantageously in the range of 0% to 80%, preferably 0% to 20%, especially 0% to 5%. The molar ratio of O ₂ is advantageously in the range of 0% to 5%, preferably 0% to 2%, more preferably 0% to 1%, especially 0% to 0.5%. The molar ratio of H ₂ O is advantageously from 0% to 99%, preferably from 0% to 90%, more preferably from 0% to 40%, even more preferably from 0% to 20%, still more preferably from 0% to 15%, more preferably 0% to 10%, especially 0% to 5%.

Advantageously, the pressure of the reactant gases in the contact with the catalyst is in the range from 3 bar _abs to 60 bar _abs , in particular from 10 bar _abs to 30 bar _abs .

Advantageously, the temperature of the reactant gas is in the range of from 600 ° C to 1300 ° C, preferably from 750 ° C to 1200 ° C, especially from 850 ° C to 1200 ° C, when contacted with the catalyst.

Advantageously, the GHSV of the method is at a value in the range of from 2000 h ^-1 to 700 000 h ^-1 , preferably from 5000 h ^-1 to 500 000 h ^-1 , especially from 10 000 h ^-1 to 300 000 h ^-1 .

The process of the present invention can advantageously be carried out in an ATR (auto-thermal reforming) process, which is described, for example, in Reimert et al., 2011, Gas Production, 2. Processes. Ullmann's Encyclopedia of Industrial Chemistry. In the case of the ATR process, oxygen is introduced in addition to the reactant gases.

The process of the invention for hydrogenating carbon dioxide in the presence of a hydrocarbon (advantageously methane) and/or water, optionally characterized by the use of ZrO ₂ -containing Z ₂ having a relatively low content of rhodium and/or rhodium The active composition is possible. For example, high conversion can also be obtained with the active composition having, for example, only 1% by weight or less than 1% by weight of lanthanum and/or cerium.

Another feature of the process of the present invention is the use of a load-type catalyst that can be readily produced, the performance of which is comparable to the prior art of using an unsupported catalyst that must be produced in a complex manner that has been demonstrated. In addition, good performance can be achieved at high loads, such as GHSV of 80 000 h ^-1 .

Another advantage of the process of the present invention is that the process of the present invention can be carried out with a small amount of water vapor in the reactant fluid. In a preferred embodiment, the water vapor/carbon dioxide content in the reactant gas is less than 0.2, more preferably less than 0.1 and even more preferably less than 0.05.

The performance of the method of the invention at low water content provides the advantage of a method of high energy efficiency and a simplification of the flow chart of the method in which the apparatus of the invention is employed.

In the practice of the method of the present invention, the cerium-containing and/or cerium-containing active component is subjected to considerable physical and chemical stresses because the process is carried out at a temperature in the range of from 600 ° C to 1300 ° C, wherein the process pressure is 5 It is in the range of 500 to 500 bar, preferably in the range of 10 to 250 bar and more preferably in the range of 20 to 100 bar. Although the method is characterized by extremely harsh process conditions, the specific characteristics of the materials of the present invention can largely exclude coke deposits on the catalyst, which also constitutes an advantage of the method of the present invention.

By means of the process according to the invention it is possible to carry out the process under severe process conditions, in particular at elevated temperatures and high loadings, without depositing a large amount of coke on the catalyst. A large amount of coke deposits in the context of the present invention is considered to be greater than 2% by weight of coke deposits on the catalyst; typically, coke deposits exceeding this value are manifested by a significant increase in pressure drop. Preferably, the coke deposit is at a carbon content of < 2% by weight, more preferably < 1% by weight, more preferably < 0.5% by weight, especially < 0.2% by weight, relative to the catalyst used. Due to the extremely high thermal stability of the catalyst and the operational stability under pressure at pressures of 5 to 40 bar, it can be used over thousands of hours of program run time. Example

To further illustrate the invention, several examples of producing the catalyst of the invention and using the catalyst of the invention for hydrogenation are shown. In addition, comparative examples from prior art are shown. A. Production of catalysts A.1. Production of SrIr _0.1 Al _11.9 O _19-Y hexaaluminate according to prior art WO 2013/135710

Catalyst S1 is produced similarly to prior art WO 2013/135710 and equivalent.

An appropriate amount of Sr(NO ₃ ) ₂ (4.344 g, purity 99.7 wt%) was dissolved in 250 mL of deionized water while stirring in a 500 mL beaker. An appropriate amount of IrCl ₃ *xH ₂ O solution (4096.9 μL, c = 0.5 mol/L) was added to the solution of Sr(NO ₃ ) ₂ . A dispersion of Al source (15.462 g of dispersion containing 42.51 wt% Al) was added to this solution, and a suspension was formed. The suspension was stirred for 30 minutes to homogenize. The suspension was rapidly frozen (shock-frozen) in liquid nitrogen. The frozen droplets were lyophilized at -10 ° C and 2.56 mbar.

The lyophilized powder is calcined under air to decompose nitrate and chlorine. The heating rate is 1 K/min. The samples were heated to 150 ° C, 250 ° C and 350 ° C with a residence time of 1 hour at each temperature reached. The final calcination temperature was 450 ° C and the residence time was also 1 hour; this was followed by cooling to ambient temperature.

The precalcined sample is subjected to a molding process. 3 wt% of graphite was added to the sample, which was vigorously mixed. The mixture was granulated in an automated operation using a Korsch XP1 granulator. The granulation tool has a diameter of 13 mm and is used to adjust the pellets with a height of 2 mm and the force applied is 40 kN. The pellets were comminuted and sieved to 315-500 μm.

The pulverized and sieved sample (315-500 μm) was subjected to final calcination under air to remove graphite and form the desired hexaaluminate phase. The final calcination temperature was 1400 ° C, the heating rate was 5 K/min and the residence time was 2 hours. A.2. Production of garnet material Y _2.68 Ni _0.32 Al ₅ O ₁₂ according to prior art WO15135968

Catalyst S2 was produced as described in WO 15/135968 A1. A.3. Production of Pd and Pt catalysts according to prior art US 2011/0105630

Catalysts S3 and S4 are produced by the impregnation method similar to prior art US 2011/0105630:

10 g of Al ₂ O ₃ carrier material having a particle size of 315-500 μm was weighed out in a circular porcelain plate having a diameter of 10 cm. The height of the carrier layer does not exceed a value of 5 mm. An impregnation solution consisting of 1281 μL of a 0.199 molar IrCl ₃ aqueous solution and 1919 μL of deionized water (see Table I) was added to the support material via a 0.5 mL pipette, which was maintained with a shaker (Heidolph Titramax 100 sample shaker). motion. The impregnated support was also mixed with a spatula and aged under ambient conditions for 30 minutes prior to drying.

Drying was carried out in a drying oven at 80 ° C for 16 hours. The dried sample was calcined in an oven (Nabertherm TH120 / 12) under air (6 L/min) at a heating rate of 1 K/min until the temperature was 250 ° C, 1 h residence time, heating rate of 5 K/min until The temperature was 400 ° C, 4 h residence time, and then cooled to ambient temperature. Table I: Metal salt solution A.4 Overview of catalysts from prior art

Table II summarizes the catalysts from the prior art. Table II: List of catalysts from prior art A.5. Production of rhodium and/or rhodium catalysts for use in accordance with the invention

10 g of carrier material with a particle size of 315-500 μm was weighed out in a circular ceramic disk of 10 cm diameter (see Table III). The height of the carrier layer did not exceed 5 mm. The impregnation solution (see Table IV) was added to the support material via a 0.5 mL pipette, which was kept moving with a shaker (Heidolph Titramax 100 sample shaker). The impregnated support was also mixed with a spatula and aged under ambient conditions for 30 minutes prior to drying.

Drying was carried out in a drying oven at 80 ° C for 16 hours. The dried sample was calcined in an oven (Nabertherm TH120 / 12) under air (6 L/min) at a heating rate of 1 K/min until the temperature was 250 ° C, 1 h residence time, heating rate of 5 K/min until The temperature was 400 ° C, 4 h residence time, and then cooled to ambient temperature. Table III: List of carrier materials used Table IV: List of impregnation solutions used

Table V summarizes the catalysts used in accordance with the present invention. Table V: List of Ir and Rh catalysts used in accordance with the present invention Illustrative Embodiment of Production of A5.1 Catalyst E1 (0.5 wt% Ir on Mixed Ce, La, Zr, Al Oxide)

In the production of impregnated catalysts with well-defined metal loadings, the determination of loss on ignition (LOI) is a critical aspect.

The carrier used had an LOI of 2.43%.

Calculation: Carriers corrected for loss on ignition: 10 g - 10 g × 0.0243 = 9.757 g Absolute weight of ruthenium catalyst: 9.757 × 1.005 = 9.806 g Radon loading in catalyst: 9.806 g - 9.757 g = 0.049 g 铱 Loading : 0.049 g / 9.906 g = 0.0049969 = 0.4996% Calculate the volume of IrCl ₃ solution required m _Ir = M _Ir × c _Ir × V _Ir → V _Ir = m _Ir / (M _Ir × c _Ir ) V _Ir = 0.049 g / (192.217 g × mol ^-1 × 0.199 g × mol ^-1 ) = 0.001281 L = 1281 μL Impregnated with 100% incipient wetness impregnation using a solution of deionized water and 0.199 mol IrCl ₃ solution (100% incipient wetness impregnation; ICW ) The form is impregnated. The water absorption of the spent catalyst was 320 μL/g. Absolute volume (including demineralized water and IrCl ₃ solution): 10 g × 320 μL / g = 3200 μL Deionized water volume: 3200 μL - 1281 μL = 1919 μL B. Catalytic test B.1 in the reactant gas stream Catalytic performance of catalysts in the presence of methane and in the absence of methane in hydrogenation of carbon dioxide (reverse water gas shift reaction) Table 1: Test scheme for catalytic screening Table 2: Catalyst S1-S4 (prior art) from Stage I-VI of Table 1, hydrogen conversion of E1-E6 (invention), carbon dioxide conversion and methane yield (no methane in the reactant gas) or Overview of methane conversion (methane present in reactant gases)

The catalysts used in accordance with the present invention exhibit comparable performance to the unsupported catalysts S1 and S2 from the prior art. In addition, performance is stable at all stages. The activities of the catalysts S3 and S4 from the prior art were decreased from phase V and phase VI, respectively; in addition, compared to the case of S1 and S2 and E1-E6, in stage I and phase II in which methane was not metered, H ₂ was The conversion rate is poor. Table 3: Carbon deposition from catalysts after screening according to Table 5 (indicators of stability)

No carbon deposition was observed for any of the catalysts. Table 4: Test protocols for catalytic screening of catalysts E1, E4 and E8 Table 5: Catalyst E1 (0.5 wt% Ir@Ce, La, Zr, Al oxide) from Stage I to Stage VIII of Table 4, E4 (0.5 wt% Ir@Ce on ZrO ₂ ) and E8 (0.5 Overview of hydrogen conversion, carbon dioxide conversion and methane yield (no methane in reactant gases) or methane conversion (methane present in reactant gases) of wt% Ir@35%MgO65%Al ₂ O ₃ )

All of the supports for Catalysts E1, E4 and E8 exhibited good and comparable performance even at high temperatures and pressures. Table 6: Test protocols for catalytic screening of catalysts E4, E5 and E7 Table 7: Hydrogen conversion, carbon dioxide conversion and methane of catalyst E4 (0.5% by weight Ir), E5 (0.05% by weight Ir) and E7 (0.1% by weight Ir) from Stage I to Stage XIII of Table 6 Overview of yield (no methane in reactant gases) or methane conversion (methane present in reactant gases)

The performance of catalysts E4, E5 and E9 was comparable even at loadings of only 0.05% by weight of Ir.

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Claims (13)

A method for hydrogenating carbon dioxide comprising reacting carbon dioxide with hydrogen in the presence of a catalyst, wherein the catalyst has a support material and an active composition, wherein the support materials used are Ce, La, Zr, Al, Ti An oxide of Ca, Si or Mg, SiC, MgAl spinel, Sr aluminate, La, Ba or Sr hexaaluminate, and/or mixtures thereof, and the active composition comprises at least hydrazine and/or铑 as an active component, wherein the cerium content is in the range of 0.005% by weight to 2% by weight relative to the total weight of the catalyst and the cerium content is between 0.005% by weight and <1% by weight, and in combination with the active component When the materials are in contact, the temperature of the reactant gases carbon dioxide and hydrogen is in the range of 600 ° C to 1300 ° C. The method of claim 1, wherein the niobium content is in the range of 0.005 wt% to 0.75 wt%, relative to the total weight of the catalyst. The method of claim 1, wherein the niobium content is in the range of 0.005% by weight to 1.5% by weight relative to the total weight of the catalyst. The method of any one of claims 1 to 3, wherein the reactant gas has a molar ratio of carbon dioxide of 10% to 60% and a molar ratio of hydrogen of the reactant gas of 10% to 90%, And the molar ratio of methane in the reactant gas is between 0% and 20%. The method of any one of claims 1 to 4, wherein the support materials used are zirconium dioxide, titanium dioxide and/or aluminate. The method of any one of claims 1 to 5, wherein the mash and/or mash is in a finely comminuted form on the carrier or in the active composition. The method of any one of claims 1 to 6, wherein the size of the cerium-containing and/or cerium-containing particles is in the range of 1 nm to 100 nm. The method of any one of claims 1 to 7, wherein the cerium-containing and/or cerium-containing particles are in the range of 1 nm to 10 nm. The method of any one of claims 1 to 8, wherein the doping element used in the support material is ceria, ruthenium, osmium and/or iridium. The method of any one of claims 1 to 9, wherein the catalyst comprises hydrazine as an active component. The method of any one of claims 1 to 10, wherein: (i) converting the CO ₂ -containing and H ₂ -containing reactant gas in the presence of a catalyst, wherein the catalyst has an active composition, the active composition comprising At least hydrazine and/or hydrazine as an active component, wherein the hydrazine and/or hydrazine content is in the range of 0.005 wt% to 2 wt% relative to the total weight of the catalyst, (ii) the reaction upon contact with the catalyst The pressure of the gas is in the range of 1 bar _abs to 100 bar _abs , and the temperature of the reactant gas is in the range of 20 ° C to 1400 ° C when in contact with the active composition, (iii) the value of the GHSV of the method is In the range of 1000 h ^-1 to 1 000 000 h ^-1 , (iv) the synthesis gas produced has a H ₂ /CO ratio in the range of 0.1 to 10. The method of claim 11, wherein the pressure of the reactant gas is in the range of from 3 bar _abs to 60 bar _abs when in contact with the catalyst, and the temperature of the reactant gas upon contact with the active composition The GHSV value of the method ranges from 10 000 h ^-1 to 500 000 h ^{-1 in the} range of 600 ° C to 1300 ° C, and the H ₂ /CO ratio of the synthesis gas produced is in the range of 1 to 4. The method of claim 12, wherein the reactant gas pressure is in the range of 10 bar _abs to 30 bar _abs when in contact with the catalyst, and the temperature of the reactant gas when in contact with the active composition The GHSV value of the method ranges from 10 000 h ^-1 to 300 000 h ^{-1 in the} range of 850 ° C to 1200 ° C, and the H ₂ /CO ratio of the synthesis gas produced is in the range of 1.5 to 3.