EA041339B1 - CATALYSTS CONTAINING COPPER, ZINC OXIDE, ALUMINUM AND SILICON OXIDES - Google Patents

Description

This invention relates to copper-containing catalysts, their manufacture and use in carbon monoxide shift reactions such as water gas shift reaction and methanol synthesis.

Carbon monoxide shift processes are of great importance for the processing of syngas using the water gas shift reaction and the production of alcohols such as methanol. These reactions are shown below.

CO + H ₂ O CO ₂ + H ₂

CO + 2H ₂ CHzOH

CO ₂ + ZN ₂ CHzOH + H ₂ O

The catalysts can also be used in the water gas shift reverse reaction and in the steam reforming of methanol to produce hydrogen and carbon oxides.

Catalysts for such reactions are typically prepared by forming pellets from individual fine particles of a homogeneous mixture of copper oxide and one or more oxide materials, typically including zinc oxide, that do not undergo significant reduction under the conditions of the conversion reaction process. A homogeneous mixture is usually obtained by precipitation of copper compounds and compounds that can be converted to other oxide materials, and/or precipitation of copper compounds in the presence of other oxide materials or compounds that can be converted into them, followed by calcination to convert the precipitated copper compounds and, at necessary, other components into oxides. Then granules are formed from oxide powders. To obtain an active catalyst, the formed granules are placed under reducing conditions to reduce the copper oxide in said granules to metallic copper. The reduction step is usually carried out in the reactor where the carbon monoxide conversion process will be carried out: thus, typically, the catalyst precursor, in which copper is in the form of copper oxide, is loaded into the reactor, and the reduction is carried out by passing an appropriate reducing gas mixture through it.

Catalyst activity is generally related to the surface area of metallic copper, with larger surface areas providing higher initial activity. However, the selectivity and service life of the catalyst is affected by heating, the presence of reagents and by-products in the ongoing reactions.

US6048820 describes a copper-based catalyst comprising copper oxide, zinc oxide, alumina and silicon oxide, optionally containing zirconium oxide, gallium oxide and palladium oxide, in which, with a total weight of the catalyst taken equal to 100%, the listed oxides are, in order of mention, 20-60 wt.%, 10-50 wt.%, 2-10 wt.%, 0.3-0.9 wt.%, 0-40 wt.%, 0-10 wt.% and 0-10 wt.%, respectively, and the silicon oxide is obtained from colloidal silicon oxide or silicon oxide dissolved in water. The catalyst was obtained by coprecipitation of soluble compounds of copper, zinc and aluminum and calcined at a temperature of 480-690°C. However, the initial catalytic activity of such catalysts is relatively low.

Document CN101306369 describes a methanol synthesis catalyst comprising oxides of Cu, Zn, Al and Si, in which aluminum oxide modified with silicon oxide is used as a support, Cu and Zn are active components, and the mole ratios of the constituent elements are: Cu:Zn: Al:Si is (5-6):(2-3):(0.8-1):(0.0016-0.05). The method used to prepare the catalyst is divided into three steps: first, a co-precipitation method is used to obtain co-precipitated Al and Si compounds; secondly, the co-precipitation method is used to obtain co-precipitated Cu and Zn compounds; and finally, the two co-precipitates thus obtained are mixed with each other in a given ratio and aged, then filtered, washed, dried and calcined. The inventors have found that the catalysts obtained in this way have a relatively low stability.

US9314774 describes a methanol synthesis catalyst comprising copper, zinc, aluminum and silicon, having a mole ratio of zinc to copper from 0.5 to 0.7, a mole ratio of silicon to copper from 0.015 to 0.05, a ratio of maximum peak intensities from zinc to the peak from copper not more than 0.25 and the half-width (2θ) of the peak from copper from 0.75 to 2.5. The catalyst is prepared by calcining a precursor comprising copper, zinc, aluminum and silicon having (A) a mole ratio of zinc to copper in the range of 0.5 to 0.7 and (B) a mole ratio of silicon to copper in the range of 0.015 to 0.05 at temperatures from 300 to 450°C. The inventors have found that such catalysts have a relatively low initial activity.

It has been found that the combination of alumina and silica, the alumina being derived from an alumina sol, in copper catalyst compositions provides unexpectedly high initial activity coupled with increased resistance to deactivation compared to catalysts without silica or catalysts with silica in which aluminum oxide is obtained from soluble aluminum salts.

Accordingly, the present invention provides a catalyst suitable for use in carbon monoxide shift reactions in the form of oxide catalyst powder moldings, said catalyst comprising 30 to 70% by weight of copper oxide in combination with zinc oxide, alumina and silicon, with a Si:Al atomic ratio ranging from 0.005 to 0.15:1, with a BET surface area >105 m ² /g and a copper surface area >37 m ² /g catalyst.

The present invention further provides a method for producing a catalyst comprising the following steps:

(i) formation of a homogeneous mixture in an aqueous medium, including a joint precipitate of copper and zinc compounds with aluminum and silicon oxides, moreover, aluminum oxide is represented by an alumina sol, (ii) extraction, washing and drying of a homogeneous mixture to obtain a dried composition, and (iii) calcination and shaping the dried composition to form a catalyst.

The present invention further includes a process for converting carbon oxides using a catalyst.

The content of copper oxide in the catalyst (in terms of CuO) is in the range from 30 to 70% by weight. Within this range, a copper oxide content in the range of 50 to 70% by weight, preferably 60 to 70% by weight, is generally used for the synthesis of methanol, while a lower content of copper oxide is generally used for the water gas shift reaction, in particular in the range of 30 to 60% by weight.

Unless otherwise indicated, the weight fractions of metal oxides in the catalyst are determined under no-loss conditions. The content of metal oxides in the catalyst is correctly determined in the absence of losses to eliminate the variability in the catalysts caused by differences in the amounts of residual carbonate compounds and moisture on the catalyst. A particularly correct way to determine the content of metal oxides in the absence of losses is to heat the catalyst to 900°C for 2 hours in air to remove volatile compounds before measuring the content of metal oxides. The heat-treated catalyst can be stored under anhydrous conditions. The content of metal oxides in the catalyst can be determined using any appropriate elemental analysis method, such as X-ray fluorescence spectroscopy (XRF), using known techniques.

A preferred catalyst precursor composition prior to calcination to an oxide catalyst comprises a solid containing mixed metal carbonates, including hydroxycarbonates, Cu and Zn, with oxide or hydrated alumina and oxide or hydrous silica dispersed therein. The mass ratio of Cu:Zn (calculated as CuO:ZnO) may be 1:1 or more, but is preferably in the range from 2:1 to 3.5:1, in particular from 2.5:1 to 2.75: 1 for methanol synthesis catalysts and in the range of 1.4:1 to 2.0:1 for water gas shift catalysts. In the case of methanol synthesis catalysts, the catalyst preferably contains 2030 wt % zinc oxide.

The catalyst contains alumina, which may be present in an amount in the range of 5 to 20% by weight, preferably 5 to 15% by weight, more preferably 8 to 11% by weight. The alumina in the catalyst is derived from an alumina sol and may be present primarily as boehmite AlOOH and/or as a transitional alumina such as gamma alumina. The alumina in the catalyst is not present in the form of crystalline aluminosilicate. The inventors have found that alumina sol based catalysts have higher BET surface areas and copper surface areas after calcination and molding, and thus provide improved initial activity compared to catalysts made using soluble aluminum compounds.

The catalyst has a copper surface area >37 m ² /g of catalyst, preferably >40 m ² g of catalyst, more preferably >45 m ² g of catalyst, and most preferably >50 m ² g of catalyst. Copper surface areas up to about 60 m ² /g of catalyst can be provided. Such surface areas are determined appropriately on the catalyst after preparation. The surface area of copper can be easily determined using reactive frontal chromatography as described in EP-A-0202824. A particularly suitable method is as follows: the shaped catalyst elements are ground and sieved to a particle size of 0.6 to 1.00 mm. Approximately 2.0 g of ground material is weighed into a glass tube, heated to 68° C. and purged with helium for 2 minutes. The catalyst is then reduced by heating in a stream of 5 vol.% H ₂ in helium at a rate of 4°C/min up to 230°C and keeping at this temperature for 30 min until complete reduction. The recovered catalyst is cooled to 68° C. in a helium stream. A gas mixture of 2.5 vol% N2O in helium is then passed over the reduced catalyst. The released gases are passed through a gas chromatograph and the amount of released N ₂ is measured. In this case, the copper surface area per gram of unreduced catalyst can be calculated.

The properties of the calcined catalyst, especially in the case of a catalyst for methanol synthesis, can be further improved by adding one or more promoter compounds selected from Mg, Co, Mn, V, Ti, Zr or rare earth compounds. Magnesium compounds are preferred and the catalyst may contain magnesium oxide in an amount in the range of 1 to 5% by weight. Accordingly, the catalyst may suitably consist essentially of oxides of copper, zinc, aluminium, magnesium and silicon.

Silicon oxide is introduced into the catalyst in an atomic ratio of Si:Al in the range from 0.005 to 0.15:1. Thus, the amount of silica in the catalyst is relatively small and can be in the range of 0.05 to 1.50% by mass, preferably 0.2 to 1.20% by mass, more preferably 0.3 to 0.8 % by weight. Higher amounts of silica dilute the active component of the catalyst and can provide acidic sites on the catalyst that reduce selectivity in methanol production. The amount of silicon oxide in the catalyst is optimal at an atomic ratio of Si:Al in the range from 0.03 to 0.07:1. The atomic ratio of Si:Cu in the catalyst may be in the range of 0.001 to 0.018:1 or 0.004 to 0.017:1, but is preferably in the range of 0.007 to 0.009:1. The silica in the catalyst can be obtained from either a silica sol, including a silica-modified alumina sol, and/or from a water-soluble silicon compound such as an alkali metal silicate, eg potassium silicate. Organosilicates can also be used, including alkyl silicates such as tetramethylorthosilicate and tetraethylorthosilicate. The silica stabilizes the copper during use and thereby improves the long-term activity of the catalyst compared to catalysts without silica.

The BET surface area of the formed catalyst when determined using nitrogen physisorption is >105 m ² /g and preferably >107 m ² /g, more preferably >109 m ² /g, most preferably >110 m ² /g, especially >115 m ² /g. BET surface areas up to about 140 m ² /g can be achieved. The surface areas of the BET measurements are properly determined on the ground granule. Surface areas measured by BET on unshaped powders are higher and may be in the range of 120 to 160 m ² /g. It is believed that these very high BET surface areas result in part from the use of the alumina sol manufacturing process and provide a stable support for fine copper.

In the catalyst, zinc oxide, oxides of alumina and silicon, as well as promoter oxide, if present, are not significantly reduced to metal under the conditions of the carbon monoxide conversion process, and, as a rule, they are present in the catalyst in the form of oxides. The copper oxide may be reduced either ex-situ or in-situ prior to use to form crystallites of catalytically active copper metal.

A copper-containing oxide catalyst is obtained by a method including the step of forming a homogeneous mixture in an aqueous medium, including a joint precipitate of copper and zinc compounds with aluminum and silicon oxides, moreover, aluminum oxide is represented by alumina sol. Such a co-precipitate can be obtained by mixing an acidic aqueous solution containing copper and zinc compounds in an appropriate ratio and combining it with an aqueous solution of an alkaline precipitant. The copper and zinc compounds are preferably nitrates. Promoter compounds such as Mg or Zr nitrates can be included in the acidic aqueous solution of copper and zinc compounds. The alkaline precipitant may be an alkali metal carbonate, an alkali metal hydroxide, or a mixture thereof. The alkaline precipitant preferably comprises an alkali metal carbonate. Potassium or sodium precipitants may be used, but potassium precipitant is preferred because the inventors have found that it is more easily removed by washing from the precipitated composition than sodium precipitant. The reaction of an alkaline precipitant with copper and zinc compounds in an acidic aqueous solution causes the precipitation of a mixed copper-zinc precipitate. Such precipitation can be carried out at temperatures ranging from 10 to 80°C, but preferably it is carried out at an elevated temperature, i. in the range of 40 to 80° C., more preferably 50 to 80° C., especially 60 to 80° C., as this has been found to produce fine crystallites which, after calcination, provide higher copper surface areas.

Acid and alkaline solutions can be added to each other in the precipitation vessel, but preferably they are introduced into the precipitation vessel at the same time, so that the pH in the precipitation vessel is maintained in the range of 6 to 9, preferably 6 to 7, after which the resulting sediment suspension aged, preferably in a separate aging vessel, at a temperature in the range of 10 to 80°C, preferably in the range of 40 to 80°C, more preferably 50 to 80°C, especially 60 to 80°C, to obtain crystalline compounds, preferably crystalline hydroxycarbonate compounds, copper and zinc. The aging of the co-precipitate slurry can be carried out using a batch or semi-continuous procedure where the aqueous slurry of the precipitated material is held in one or more agitated vessels for selected time periods. Suspension of the co-precipitate in the liquid can be achieved by simple agitation, the intensity of agitation required being dependent on the tendency of the particles to settle and on the viscosity. Alternatively, aging of the co-sludge slurry can be carried out in a pulse flow reactor as described in WO 2008/047166, which is incorporated herein by reference. The reaction and post-treatment conditions for the co-sludge slurry can be selected to produce crystalline compounds such as manassite, rosazite, aurichalcite or malachite. Preferably, coprecipitation and aging is carried out to provide phases of malachite [Cu ₂ (CO ₃ )(OH) ₂ ], smithsonite [ZnCO ₃ ] and/or zinc malachite [(Cu/Zn) ₂ (CO ₃ )(OH) ₂ ] , which can be determined using X-ray diffraction (XRD).

The catalyst is prepared using an alumina sol. Alumina Sol is an aqueous colloidal dispersion of aluminum hydroxide, including boehmite and pseudoboehmite. The pH of the dispersion may suitably be <7, preferably in the range of 3 to 4. The alumina sol may suitably be added to the precipitation vessel. Preferably, the alumina sol is added to the precipitation vessel separately from the acidic metal solution or alkaline precipitant solution, as this has been found to improve the properties of the catalyst. Alumina sols are commercially available or can be prepared by known methods. The concentration of aluminum oxide in the ash can be from 30 to 200 g/l. Particularly suitable for the purposes of the present invention, alumina sols include dispersions of colloidally dispersed boehmite with an average particle size D50 in the range of 5 to 200 nm, preferably 5 to 100 nm, more preferably 5 to 50 nm, in a dispersed state. Such sols are commercially available.

The catalyst contains silicon oxide. If a silica sol is used as the silica, it can be added to the acid metal solution and/or the alumina sol and/or added to the precipitation vessel and/or the aging vessel. Silica sols particularly suitable for the purposes of the present invention include aqueous dispersions of colloidally dispersed silica with a particle size in the range of 10-20 nm. The pH of the dispersion may be <7, preferably between 2 and 4. The concentration of silica in the ash may be 100-400 g/l. Such sols are commercially available, such as Snowtex-O from Nissan Chemicals and HSA from Grace Ludox. Alternatively, the silica can be added as a silica-modified alumina sol. Particularly suitable for the purposes of the present invention, silica-modified alumina sols include dispersions of colloidally dispersed silica-modified boehmite. Such sols are commercially available, for example Sasol Siral 5D.

When using a water soluble silicate such as an alkali metal silicate as the silica source, it can be added to the alkaline precipitant solution and/or to the alumina sol and/or to the precipitation vessel and/or to the aging vessel. Suitable alkali metal silicates for the purposes of the present invention are soluble sodium silicates and soluble potassium silicates. Such alkali metal silicates are commercially available, for example Kasil 1 from PQ Corporation, Kasolv 16 from PQ Corporation or Zacsil 18 from Zaclon LLC. When using an alkali metal silicate as a source of silica in the catalyst, the alkali metal contained in the alkali metal silicate is preferably the same as the alkali metal in the precipitant solution, as this improves washability, catalyst recovery, and recycling of waste solutions in large-scale production. The amount of silicon, calculated as SiO ₂ , in the alkali metal silicate solution can be in the range of 15-30% by weight.

When using an organosilicate as the source of silica, such as an alkyl silicate of the formula Si(OR)4, where R = Ci-C ₄ alkyl, since it will hydrolyze on contact with water, it is preferably added to the alumina sol or precipitation vessels and/ or aging.

After coprecipitation and aging, the homogeneous mixture is recovered, for example by separation from the mother liquors using known methods such as filtration, decantation or centrifugation, and washed to remove residual soluble salts.

Washing of a homogeneous mixture can be carried out using standard equipment such as frame filter presses, for example by resuspension of the mixture one or more times in demineralized water or by dynamic tangential flow filtration using an Artisan or Shriver thickener prior to extraction. For methanol synthesis catalysts, the alkali metal content of the recovered and dried mixture is desirably reduced to less than 0.2 wt.%, preferably less than 0.1 wt.%, based on the corresponding alkali metal oxide on the dried material under no loss conditions, since the alkali the metal has a negative effect on the performance of the catalyst.

The recovered homogeneous mixture is dried to obtain a dried composition. Such drying may include heating the wet mixture in discrete steps or continuously over an extended period of time until the maximum temperature is reached. The drying step can be carried out at temperatures ranging from 90 to 150°C, preferably from 90 to 130°C, in air or inert gas, using standard drying equipment such as an oven, tumble dryer, spray dryer or similar equipment.

The dried composition is usually in the form of a powder. The average particle size (when determined by screening fractions, i.e. mass average particle size) can be in the range of 10300 microns. The dried composition may include one or more copper and zinc hydroxycarbonates, and

- 4 041339 also aluminum and silicon oxides.

The dried composition is calcined and shaped to form a catalyst. The dried composition can be calcined, i. heat to convert the copper and zinc compounds, as well as any promoter compounds present, to their respective oxides prior to shaping, or, less preferably, the dried composition may be shaped into the desired elements prior to calcination. This latter method is less preferred because baking the molded elements generally reduces their strength and makes it difficult to control the density of the pellets. In the present invention, the calcination can be carried out at temperatures ranging from 275 to 450°C, preferably from 275 to 400°C, more preferably from 275 to 350°C. Lower temperatures provide lower pellet stabilities, while higher temperatures significantly reduce the initial activity created by the high dispersion of copper. The calcination can be carried out in air or in an inert gas such as nitrogen, but air or other free oxygen-containing gas is preferred. The calcined product is usually in the form of a powder.

The shaped elements are preferably pellets. Thus, the dried or calcined powder can be subjected to a granulation operation, optionally after prior compactification of the powder, which can improve the granulation process. The granule may suitably be a cylindrical granule. Cylindrical pellets for carbon monoxide conversion processes suitably have a diameter in the range of 2.5 to 10 mm, preferably 3-10 mm, and an aspect ratio (ie, length/diameter) in the range of 0.5 to 2.0. Alternatively, the shaped element may be in the form of a ring. In a particularly suitable embodiment for the purposes of the present invention, the molded body is in the form of a cylinder having two or more, preferably 3 to 7, grooves running along its length. Suitable cylindrical domed shapes having one or more grooves are described in the inventors' document WO 2010/029325, which is incorporated herein by reference.

Granules, in particular cylindrical granules with flat or domed ends as described above, are preferably provided with granule densities in the range of 1.8 to 2.4 g/cm ³ , preferably 1.9 to 2.3 g/cm ³ . The density of the granules can be easily determined by calculating the volume from the dimensions of the granule and measuring its mass. As the density increases, the volume for gas incorporation in the molded elements decreases, which in turn reduces the permeability to the reacting gases. Thus, for densities >2.4 g/cm ³ the reactivity of the catalyst may be less than optimal, despite the high volume content of copper. For densities <1.8 g/cm ³ the crush strength may not be sufficient for long term use in current carbon monoxide conversion processes.

The present invention further includes a carbon oxides conversion process that includes reacting a carbon monoxide-containing process gas containing at least one of carbon monoxide and carbon dioxide, further containing hydrogen and/or steam, in the presence of a catalyst. Accordingly, the term oxides of carbon in this document includes at least one of carbon monoxide and carbon dioxide. The catalyst may be pre-activated in-situ by passing over it a reducing gas stream, preferably including hydrogen, to convert copper oxide to elemental copper. Thus, the present invention preferably includes the steps of (i) activating the catalyst by bringing it into contact with a reducing gas stream and (ii) reacting a carbon monoxide containing process gas containing at least one of carbon monoxide and carbon dioxide further containing hydrogen and/ or steam, in the presence of a catalyst to form a product stream. Activation can be carried out using a hydrogen-containing gas, including syngas containing hydrogen and oxides of carbon, at temperatures above 80° C. and pressures in the range of 150 barg. The maximum reduction temperature is desirably between 150 and 300°C.

The present invention includes processes using the described catalyst, in particular the following.

A. The synthesis of methanol, in which a gas mixture containing one or both oxides of carbon (i.e. carbon monoxide and/or carbon dioxide) and hydrogen, is passed over a catalyst at a temperature in the range of 200-320°C, a pressure in the range of 20- 250, especially 30-120 bar abs. and spatial velocity in the range of 500-20000 h ^-1 . The process can be organized using a single or repeated pass and may include cooling by indirect heat exchange with surfaces in contact with the reacting gas, or by splitting the catalyst bed into parts and cooling the gas between parts of the catalyst by introducing colder gas. For such a process, the catalyst preferably contains copper, zinc oxide and optionally magnesium oxide, as well as oxides of aluminum and silicon. Catalysts can be used in methanol synthesis processes where natural gas is steam reformed and/or autothermal reformed with oxygen to form synthesis gas containing carbon monoxide, carbon dioxide and hydrogen, or in processes where synthesis gas is richer in carbon monoxide and obtained by gasification of coal or biomass or municipal waste. The catalyst may be particularly suitable for use in methanol synthesis processes, syn-

- 5 041339 mes-gas is formed essentially from hydrogen and carbon dioxide, especially when the hydrogen and/or carbon dioxide is obtained from renewable sources, such as the electrolysis of water to extract hydrogen and the extraction of CO2 from off-gases, such as combustion gas or gas from organic waste.

B. Modified methanol synthesis, in which the catalyst also contains free alumina with a surface area of 50-300 m2 g ^-1 or other acidic catalyst, so that the synthesis product is relatively rich in dimethyl ether. Temperatures, pressures and space velocities are similar to those used in the synthesis of methanol, but the synthesis gas may contain hydrogen and carbon monoxide in a molar ratio of less than 2.

C. A low temperature water gas shift reaction in which a gas containing carbon monoxide (preferably less than 4% v/v dry gas) and steam (in which the molar ratio of steam to total dry gas is typically in the range from 0.3 to 1.5), is passed over the catalyst in an adiabatic fixed bed at an outlet gas temperature in the range from 200 to 300°C at a pressure in the range of 15-50 bar abs. Typically, the inlet gas is a high temperature shift product where the carbon monoxide content has been reduced by reaction over a high temperature shift catalyst such as an iron catalyst or a zinc aluminate catalyst at an exit gas temperature in the range of 400 to 500°C, followed by cooling by indirect heat exchange. . The content of carbon monoxide at the exit from the stage of low temperature shift is usually in the range from 0.1 to 1.0%, especially below 0.5 vol./vol.% in terms of dry gas.

D. Medium temperature shift, in which a gas containing carbon monoxide and steam is supplied at a pressure in the range of 15-50 bar abs. onto the catalyst at an inlet gas temperature typically in the range of 200 to 240°C, although the inlet temperature may be up to 280°C and the outlet temperature is typically up to 300°C, but may be up to 360°C. These conditions are more stringent than in process B, so it is expected that the use of a new catalyst in this case will be particularly advantageous.

E. Low-medium temperature heat transfer reforming in which the reaction in the catalyst bed proceeds in contact with heat transfer surfaces. The standard coolant is water at such a pressure that partial or complete boiling occurs. The corresponding pressure is between 15 and 50 bar abs, and the resulting steam can be used, for example, to drive a turbine, or to supply process steam to the reforming process itself, or to an upstream stage where the feed gas for the reforming process is generated. The water may be in tubes surrounded by a catalyst, or vice versa.

F. Methanol reforming, in which a methanol gas stream is combined with steam and/or carbon dioxide and reacted, typically at temperatures in the range of 250 to 360° C. and typical pressures in the range of 10 to 30 bar abs., over a catalyst to obtain a gas mixture containing hydrogen and carbon oxides. Hydrogen can be recovered from the gas mixture using standard separation methods such as pressure swing adsorption or hydrogen permeable membranes.

The present invention is particularly suitable for the production of methanol synthesis catalysts.

The present invention will be further described with reference to the following examples.

In the examples, unless otherwise indicated, the catalysts were prepared on a scale of 4-7 liters by simultaneously adding a mixed solution of metal nitrates, an alkali metal precipitant solution, and an aqueous dispersion of alumina sol to a 1-liter stirred precipitation vessel at a temperature of 65 to 70 °C The aging of the co-precipitate slurry was carried out in a separate stirred vessel for up to 2 hours, also at a temperature of 65 to 70°C. Silica was added to the catalyst in various ways at different stages of the production process. The aged sediment suspensions were filtered and washed with demineralized water. Drying and calcination of the washed precipitate was carried out, unless otherwise indicated, at temperatures of 110°C and 300-300°C, respectively. The resulting powders were compacted into molded elements, which were then ground into crumb particles suitable for testing.

The sols used were aqueous. The sols had the following properties.________

Alumina Sol Silica Modified Alumina Sol Silica sol Dispersed phase Dispersible boehmite Dispersible Sim-modified boehmite silicon oxide AUOH (wt%) 82-92 76-86 - S1O2 (wt%) - 3.4-3.8 20-21 Dispersed particle size D50 (nm) 5-50 <200 10-20 sol pH 3.5-4 2-4 2-4

Copper surface areas were determined on the crushed granules using reactive frontal chromatography as described above on the catalyst after preparation.

- 6 041339

Particle size measurements were made using a disc centrifuge.

The content of metal oxides was determined and adjusted under lossless conditions by heating a known mass of catalyst powder after preparation in a crucible in a preheated oven at 900° C. for 2 hours in air. The crucible was then cooled in a closed and ventilated desiccator and reweighed to determine the weight loss. Heat-treated catalysts were analyzed for their metal content using x-ray fluorescence (WD-XRF) using known methods.

BET surface areas were determined on crushed granules, after drying, using nitrogen physical sorption on a Micromeritics 2420 ASAP physical sorption analyzer in accordance with ASTM Method D 366303; standard surface area test. Nitrogen was used as the adsorbate, and the measurements were carried out at liquid nitrogen temperature (77 K). The cross-sectional area of the nitrogen molecule was taken equal to 16.2 A ² . Prior to analysis, the samples were degassed by purging with dry nitrogen gas for a minimum of 1 hour at the optimum temperature. Received five pairs of data relative pressure/volume for the area of relative pressure from 0.05 to 0.20 P/P _o inclusive. The equilibrium time for each point was 10 s.

Example 1

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 4.4:1.7:1.0:0.2:0.04 and a copper oxide content of 64.4 wt.% was obtained by co-precipitation of a mixed solution of metal nitrates, including copper, zinc and magnesium nitrates, potassium carbonate solution, while adding a mixture of alumina sol and silica sol to the precipitation vessel, at pH 6.3-6.8 and temperature in the range of 65-70°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 330°C for 6 h.

Example 2

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 5.1:1.9:1.0:0.04 and a copper oxide content of 66.1 wt.% was obtained as described in example 1, without magnesium nitrate, and also with calcination in air at a temperature of 300°C for 6 hours.

Example 3

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 4.5:1.7:1.0:0.2:0.006 and a copper oxide content of 64.5 wt.% was obtained as described in example 1, with calcination in air at 305°C for 6 hours.

Example 4

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 4.5:1.7:1.0:0.2:0.08 and a copper oxide content of 64.2 wt% was prepared as described in Example 1 , with calcination in air at 305°C for 6 hours.

Example 5

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 6.7:2.5:1.0:0.3:0.11 and a copper oxide content of 66.1% by weight was prepared as described in Example 1 , with calcination in air at 305°C for 6 hours.

Example 6

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 3.3:1.2:1.0:0.1:0.06 and a copper oxide content of 62.2 wt.% was obtained as described in example 1 , with calcination in air at 305°C for 6 hours.

Example 7

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 5.4:2.0:1.0:0.2:0.04 and a copper oxide content of 65.9 wt.% was obtained by co-precipitation of a mixed solution of metal nitrates, including copper, zinc and magnesium nitrates, potassium carbonate solution, while adding alumina sol doped with silicon oxide to the precipitation vessel, at pH 6.3-6.8 and temperature in the range of 65-70°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 330°C for 6 h.

Example 8

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 4.3:1.7:1.0:0.04 and a copper oxide content of 64.6 wt.% was obtained by co-precipitation of a mixed solution of metal nitrates, including copper and zinc nitrates and silica sol, with a solution of potassium carbonate, while adding to the vessel for the deposition of alumina sol, at a pH of 6.3-6.8 and a temperature in the range of 65-70°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 300°C for 6 h.

Example 9

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 4.0:1.5:1.0:0.03 and a copper oxide content of 64.4 wt. copper and zinc, potassium carbonate solution, while adding alumina sol to the precipitation vessel, at pH 6.3-6.8 and temperature in the range of 65-70°C. Silica sol was added to the resulting coprecipitate. The resulting mixture was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 300°C for 6 h.

Example 10

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 4.4:1.7:1.0:0.2:0.04 and a copper oxide content of 63.2 wt.% was obtained by co-precipitation of a mixed solution of metal nitrates, containing nitrates of copper, zinc and magnesium, with a solution of potassium carbonate, while adding alumina sol containing soluble potassium silicate to the precipitation vessel at pH 6.3-6.8 and temperature in the range of 65-70°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 305°C for 6 h.

Example 11.

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 4.2:1.6:1.0:0.03 and a copper oxide content of 64.4 wt.% was obtained by co-precipitation of a mixed solution of metal nitrates, including copper and zinc nitrates, a solution containing potassium carbonate and potassium silicate, while adding alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature in the range of 65-70°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 300°C for 6 h.

Example 12.

An oxide catalyst with a Cu:Zn:Al:Mg:Si molar ratio of 4.2:1.2:1.0:0.2:0.04 and a copper oxide content of 67.8 wt% was obtained by co-precipitation of a mixed solution of metal nitrates, including copper, zinc and magnesium nitrates, with a solution of potassium carbonate, while adding alumina sol and silica sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature in the range of 6570°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 300°C for 6 h.

Comparative example 1.

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 3.8:2.2:1.0:0.04 and a copper oxide content of 56.6% by weight was prepared according to the procedure described in Example 2 of US Pat. No. 6,048,820. The mixed metal nitrate solution containing copper, zinc and aluminum nitrates, silica sol and sodium carbonate solution were simultaneously added with stirring to demineralized water in a precipitation vessel at room temperature. The resulting precipitate was aged for 24 h at room temperature, filtered, washed with demineralized water, dried, and calcined in air at 600°C for 2 h.

Comparative example 2.

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 3.8:2.2.2:1.0:0.04 and a copper oxide content of 56.6% by weight was prepared as described in Comparative Example 1 with calcination at a temperature 305°C for 6 hours

Comparative example 3.

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 3.3:1.5:1.0:0.01 and a copper oxide content of 60.1% by weight was prepared according to the procedure described in Example 5 of CN 101306369A. . The aluminum nitrate solution was co-precipitated with a solution of sodium carbonate and sodium silicate at pH 7.0-7.2 and 80° C. to give precipitate A. This material was not a stable colloidal suspension and settled within a few hours. The analysis showed that the average particle size D50 was 226 nm. Separately, a solution of copper and zinc nitrates was co-precipitated with a solution of sodium carbonate at pH 7.0-7.2 and a temperature in the range of 65-70°C to obtain precipitate B. Precipitate A was added to precipitate B in a volume ratio of 1:7. The resulting mixture was aged at 70°C for 2 h, filtered, washed with demineralized water, dried, and calcined in air at 340°C for 4 h.

Comparative example 4.

An oxide catalyst as described in US 4,788,175 with a Cu:Zn:Al:Mg molar ratio of 4.4:1.6:1.0:0.2 and a copper oxide content of 64.2% by weight was prepared by coprecipitation of a mixed solution of metal nitrates, including copper, zinc and magnesium nitrates, potassium carbonate solution, while adding alumina sol to the precipitation vessel, at pH 6.3-6.8 and temperature in the range of 65-70°C. The resulting precipitate was aged for up to 2 h at a temperature of 65–70°C, filtered, washed with demineralized water, dried, and calcined in air at a temperature of 330°C for 6 h.

Comparative example 5.

An oxide catalyst with a Cu:Zn:Al:Si molar ratio of 6.2:3.4:1.0:0.08 and a copper oxide content of 59.5% by weight was prepared according to the procedure described in Example 2 of US9314774.

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The sodium carbonate solution was added with stirring to a mixed metal nitrate solution containing copper, zinc and aluminum nitrates, silica sol, at room temperature. The resulting precipitate was aged at 70°C for 2 h, filtered, washed with demineralized water, dried, and calcined in air at 350°C for 2 h.

Comparative example 6.

An oxide catalyst with a Cu:Zn:Zr:Al:Si molar ratio of 4.8:3.3:1.6:1.0:0.12 and a copper oxide content of 42.5 wt.% was obtained in accordance with the procedure described in Comparative Example 5 of US 9314774. A mixed metal nitrate solution containing copper, zinc, aluminum and zirconium nitrates, silica sol and sodium carbonate solution were simultaneously added with stirring to demineralized water in a precipitation vessel at room temperature. The resulting precipitate was aged at 70°C for 2 h, filtered, washed with demineralized water, dried, and calcined in air at 400°C for 2 h.

Testing in a microreactor

A sample of each of the catalysts was ground and sieved to collect a fraction with a particle size of 0.61.0 mm. A standard microreactor was used in the experiments. The crushed catalyst samples were completely reduced with a gas mixture containing 2 vol./vol.% hydrogen in nitrogen at a temperature of 225°C. Then, over the samples of catalysts, a technological mixture of gases with a composition of 6 vol./vol.% CO, 6 vol./vol.% CO ₂ , 9 vol./vol.% N ₂ and 79 vol./vol.% H ₂ was passed over. Recovered catalyst samples were exposed to a process gas mixture at 225°C, 40,000 l/h/kg, 50 barg. at the start of work. After some time, the samples of the catalysts were transferred to deactivation conditions at more than 300°C to simulate severe operating conditions and accelerate the effects of aging. At the start of work and after keeping the catalyst under deactivation conditions, analytical scanning of product gas flows was performed. Analytical flow scans were performed by varying the mass velocity at 225°C, 50 barg. An IR analyzer was used to determine the volumetric concentration of gas flows leaving the reactor. Analytical flow scan data was used to calculate the relative activity of the test material compared to the reference catalyst, which in these experiments used the catalyst of Comparative Example 1. Relative activities were calculated from the ratio of the flow rates through each catalyst at constant conversion relative to the flow rate through the standard catalyst. The results are presented in the table below. ____________________________

Sample Source A1 Surface area (BET method) (m ² /g) CuO content (wt%) Surface area Cu (m ² /g catalyst) Atomic ratio Si:Al Activity relative to avg. pr. 1 in 16 hours Activity relative to avg. pr. 1 after 340 h Example 1 sol 119.4 64.4 52.8 0.04 1.60 1.46 Example 2 sol 121.3 66.1 42.7 0.04 1.61 1.39 Example 3 sol 120.5 64.5 52.1 0.006 1.61 1.31 Example 4 sol 120.8 64.2 54.7 0.08 1.57 1.38 Example 5 sol 115.5 66.1 52.9 0.11 1.60 1.29 Example 6 sol 121.6 62.2 47.6 0.06 1.50 1.34 Example 7 sol 111.3 65.9 50.5 0.04 1.54 1.41 Example 8 sol 114.4 64.6 39.7 0.04 1.44 1.47 Example 9 sol 125.4 64.4 41.6 0.03 1.51 1.37 Example 10 sol 123.7 63.2 54.9 0.04 1.64 1.47 Example 11 sol 111.8 64.4 44.5 0.03 1.64 1.43 Example 12 sol 127.6 67.8 49.6 0.04 1.55 1.32 Comparative Example 1 nitrate 98.9 56.6 30.1 0.04 1.00 1.00 Comparative Example 2 nitrate 94.7 56.6 29.5 0.04 0.74 0.84 Comparative Example 3 nitrate 103.9 60.1 33.1 0.01 1.16 0.95 Comparative Example 4 sol 108.7 64.2 51.7 0 1.43 1.09 Comparative Example 5 nitrate 41.9 59.5 6.1 0.08 0.29 0.28 Comparative Example 6 nitrate 86.8 42.5 17.7 0.12 0.73 0.67

Comparative Example 4, prepared using an alumina sol in a manner similar to Examples 1-11 but without silica, has a high initial activity but a poorer long-term activity.

Aluminum nitrate based products in Comparative Examples 1, 5 and 6 have the worst initial

Claims (26)

new and long-term activity. This state of affairs is maintained even when the calcination conditions are changed to match those of Example 1 (Comparative Example 2). Comparative Example 3, obtained by separate co-precipitation of silica-alumina co-precipitation using aluminum nitrate, also provided a catalyst with worse activity retention. CLAIM 1. Catalyst suitable for use in carbon monoxide shift reactions, in the form of molded elements from powder oxide catalyst, and the specified catalyst includes from 30 to 70% by weight of copper oxide in combination with zinc oxide, oxides of aluminum and silicon, at an atomic ratio of Si :Al ranging from 0.005 to 0.15:1, with BET surface area >105 m ² /g and copper surface area >37 m ² /g catalyst. 2. The catalyst according to claim 1, which is a methanol synthesis catalyst comprising copper oxide in an amount in the range of 50 to 70% by weight, preferably 60 to 70% by weight. 3. The catalyst according to claim 2, wherein the weight ratio of CuO:ZnO is in the range of 2:1 to 3.5:1, preferably in the range of 2.5:1 to 2.75:1. 4. The catalyst according to claim 2 or 3, containing from 20 to 30% by weight of zinc oxide. 5. The catalyst according to any one of claims 1 to 4, containing alumina in an amount in the range of 5 to 20% by weight, preferably 5 to 15% by weight, more preferably 8 to 11% by weight. 6. The catalyst according to any one of claims 1 to 5, having a copper surface area of >40 m ² /g of catalyst, preferably >45 m ² /g of catalyst, more preferably >50 m ² /g of catalyst. 7. The catalyst according to any one of claims 1 to 6, further comprising one or more promoter compounds selected from compounds of Mg, Co, Mn, V, Ti, Zr or rare earth elements, preferably magnesium compounds, more preferably magnesium oxide in an amount in the range from 1 to 5% by weight. 8. The catalyst according to any one of claims 1 to 7, wherein the amount of silica in the catalyst is in the range from 0.05 to 1.50% by weight, preferably from 0.2 to 1.20% by weight, more preferably from 0 .3 to 0.8% by weight. 9. A catalyst according to any one of claims 1 to 8, wherein the Si:Al atomic ratio is in the range of 0.03 to 0.07:1. 10. The catalyst according to any one of claims 1 to 9, wherein the Si:Cu atomic ratio is in the range of 0.001 to 0.018:1, preferably 0.004 to 0.017:1, more preferably 0.007 to 0.009:1. 11. The catalyst according to any one of claims 1 to 10, wherein the BET surface area of the catalyst when determined using nitrogen physisorption is >107 m ² /g, preferably >109 m ² /g, more preferably >110 m ² /g, and most preferably >115 m ² /g. 12. A method for producing a catalyst according to claim 1, including the following stages: (i) formation of a homogeneous mixture in an aqueous medium, including a joint precipitate of copper and zinc compounds with aluminum and silicon oxides, moreover, aluminum oxide is represented by alumina sol, (ii) extraction, washing and drying the homogeneous mixture to obtain a dried composition; and (iii) calcining and shaping the dried composition to obtain a catalyst. 13. The method of claim 12 wherein the co-precipitate is obtained by mixing an acidic aqueous solution containing copper and zinc compounds and combining it with an aqueous solution of an alkaline precipitant in a precipitation vessel. 14. Process according to claim 13, wherein the copper and zinc compounds are nitrates and the alkaline precipitant comprises an alkali metal carbonate, preferably potassium carbonate. 15. The method according to claim 14, wherein the precipitation is carried out at temperatures in the range of 40 to 80°C, preferably 50 to 80°C, especially 60 to 80°C. 16. The method according to any one of claims 13 to 15, wherein the co-sludge is aged in a separate aging vessel at a temperature in the range of 10 to 80°C, preferably in the range of 40 to 80°C, more preferably 50 to 80° C, especially between 60 and 80°C. 17. The method according to any one of claims 13 to 16, wherein the alumina sol is added to the precipitation vessel separately from the acidic metal solution or the alkaline precipitant solution. 18. The method according to any one of claims 12-17, wherein the alumina sol is a dispersion of colloidally dispersed boehmite with an average particle size D50 in the range of 5 to 200 nm, preferably 5 to 100 nm, more preferably 5 to 50 nm in dispersed condition. 19. The method according to any one of claims 13-18, wherein the silica in the catalyst is derived from a silica sol, including a silica-modified alumina sol, and/or from a water-soluble silicon compound such as an alkali metal silicate, or from an organosilicate. 20. The method according to claim 19, wherein the silica sol is added to the acid metal solution and/or the alumina sol and/or added to the precipitation vessel and/or the aging vessel. - 10 041339 21. The method according to claim 19, wherein the alkali metal silicate is added to the alkaline precipitant solution and/or the alumina sol and/or to the precipitation vessel and/or to the aging vessel. 22. The method according to any one of paragraphs. 12-21, wherein the drying step is carried out at a temperature in the range 90-150°C. 23. The method according to any one of paragraphs. 12-22, wherein the shaped composition is a cylindrical pellet with a diameter in the range of 2.5 to 10 mm, preferably 3 to 10 mm, and an aspect ratio (length/diameter) in the range of 0.5 to 2.0 . 24. The method according to any one of paragraphs. 12-23, wherein the calcination step is carried out at a temperature in the range of 275 to 450°C, preferably 275 to 400°C, more preferably 275 to 350°C. 25. The method of conversion of carbon oxides, which includes the reaction containing carbon monoxide process gas containing at least one of carbon monoxide and carbon dioxide, additionally containing hydrogen and/or steam, in the presence of a catalyst according to any one of paragraphs. 1-11 or obtaining the method according to any one of paragraphs. 12-24. 26. The process for shifting carbon oxides according to claim 25, wherein the process is selected from methanol synthesis and a water gas shift reaction. Kommersant Eurasian Patent Organization, EAPO Russia, 109012, Moscow, Maly Cherkassky per., 2 -