Copper-containing catalysts

Abstract

A catalyst suitable for use in carbon oxide conversion reactions is described, said catalyst in the form of a shaped unit formed from an oxidic catalyst powder comprising copper oxide, zinc oxide, alumina and phosphorus, having copper oxide content in the range of 30 to 75% by weight, a Cu:Zn atomic ratio greater than 1.1:1, and a phosphorus content, expressed as P2O5, in the range of 0.1 to 1.1 % by weight.

Description

[0001] P102379

[0002] 1

[0003] Copper-containing catalysts

[0004] This invention relates to copper-containing catalysts, their manufacture and use in carbon oxide conversion reactions, such as the water-gas shift reaction and methanol synthesis.

[0005] 5 Carbon oxide conversion processes are of considerable importance in the manipulation of synthesis gas by the water-gas shift reaction and the production of alcohols such as methanol. These reactions are depicted below.

[0006] CO + H2O ->• CO2+ H2

[0007] CO + 2H2->• CH3OH

[0008] CO2+ 3H2->• CH3OH + H2O

[0009] The catalysts may also be used in the reverse water-gas shift reaction and in the steam reforming of methanol to produce hydrogen and carbon oxides.

[0010] 15

[0011] The catalysts for such reactions are generally produced by forming into pellets small discrete particles of an intimate mixture of copper oxide and one or more oxidic materials, generally including zinc oxide, that are not substantially reduced under the conversion reaction process conditions. The intimate mixture is generally made by precipitation of copper compounds and

[0012] 20 compounds convertible to the other oxidic materials, and / or precipitation of the copper compounds in the presence of the other oxidic materials or compounds convertible thereto, followed by calcination to convert the precipitated copper compounds, and other components as necessary, to the oxides. Hence pellets are formed from oxidic powders. In order to generate the active catalyst, the pellets are subjected to reducing conditions to reduce the

[0013] 25 copper oxide in said pellets to metallic copper. The reduction step is normally carried out in the reactor where the carbon oxide conversion process is to be effected: thus normally a catalyst precursor in which the copper is present in the form of copper oxide is charged to the reactor and the reduction effected by passing a suitable reducing gas mixture there-through.

[0014] Activity of the catalysts is generally related to the metallic copper surface area, with higher surface areas providing higher initial activity. However, catalyst selectivity and longevity in use may be affected by the other components in the catalyst.

[0015] US4547482 discloses a catalyst composition comprising copper oxide, zinc oxide and an

[0016] 35 oxyacid of phosphorus or its salt; and a method for producing methanol by reacting carbon monoxide and / or carbon dioxide with hydrogen in the vapor phase in the presence of a catalyst, wherein the catalyst is the aforesaid catalyst composition which has been activated by reduction with a hydrogen-containing gas. The phosphorus component was used to replace the conventional alumina component. Similarly, JPS6097048(A) discloses a catalyst P102379

[0017] 2 comprising copper oxide, zinc oxide, oxysalt of phosphorus and / or silicon oxide and a compound of an element selected from K, Rb and Cs. This catalyst composition can be appropriately selected in such a range that Cu / Zn=0.2-3, PZ Zn=0.002-0.075, Si / Zn=0.001 -0.07 and K, Rb or Cs / Zn =0.02-0.1 on the basis of atomic ratio.

[0018] 5

[0019] CN110935478 (A) discloses a parallel precipitation method for a methanol synthesis catalyst. The synthetic methanol catalyst prepared by the method comprises the following components based on the weight of the catalyst: CuO is 20% to 62%, preferably 25% to 57%, ZnO is 15% to 35%, preferably 15% to 30%, AI2O3 is 5% to 25%, preferably 6% to 23%, and element A oxide is 2% to 20%, preferably 7% to 17%; wherein element A is one or more of boron, phosphorus or silicon.

[0020] CN107721821 (A) discloses a method for preparing 1 , 3-propanediol using a hydrogenation catalyst composed of a carrier and an active component, where the active component includes,

[0021] 15 by mass, 10-50% of CuO, 2-30% of ZnO, 0.5-15% of ZrO2and 0-3% of P2O5.

[0022] We have found a combination of alumina and small amounts of phosphorus, provides a surprisingly high initial activity combined with an improved resistance to deactivation in carbon oxide conversion reactions compared to phosphorus-free catalysts or catalysts containing

[0023] 20 higher levels of phosphorus.

[0024] Accordingly, the invention provides a catalyst suitable for use in carbon oxide conversion reactions, said catalyst in the form of a shaped unit formed from an oxidic catalyst powder comprising copper oxide, zinc oxide, alumina and phosphorus, having copper oxide content in

[0025] 25 the range of 30 to 75% by weight, a Cu:Zn atomic ratio greater than 1.1 :1 , and a phosphorus content, expressed as P2O5, in the range of 0.1 to 1.1 % by weight.

[0026] The invention further provides a method for making the catalyst comprising the steps of:

[0027] (i) forming, in an aqueous medium, an intimate mixture comprising a co-precipitate of copper, zinc, aluminium and phosphorus compounds,

[0028] (ii) recovering, washing and drying the intimate mixture to form a dried composition, and

[0029] (iii) calcining and shaping the dried composition to form the catalyst.

[0030] The invention further comprises a carbon oxides conversion process using the catalyst.

[0031] 35

[0032] The copper oxide content of the catalyst (expressed as CuO) is in the range of 30 to 75% by weight. Within this range a copper oxide content in the range of 50 to 75% by weight, preferably 60 to 70% by weight, is of general application for methanol synthesis, whereas for P102379

[0033] 3 the water-gas shift reaction, the copper oxide content is generally lower, particularly in the range of 30 to 60% by weight.

[0034] Unless otherwise stated, the weight percentages of the metal oxides in the catalyst are

[0035] 5 determined on a loss-free basis. The metal oxide contents in the catalyst are suitably determined on a loss-free basis, to remove variability in the catalysts caused by differences in the amount of residual carbonate compounds and moisture on the catalyst. A particularly suitable method for determining the metal oxide content on a loss-free basis is to heat the catalyst to 900°C for 2 hours in air to remove volatiles before measuring the metal oxide contents. The heat-treated catalyst may be stored under anhydrous conditions. The metal oxide content of the catalysts may be determined using any suitable elemental analysis technique, such as X-ray fluorescence spectroscopy (XRF) using known techniques.

[0036] The catalyst contains zinc oxide. The weight ratio of Cu:Zn (expressed as CuO:ZnO) is greater

[0037] 15 than 1.1 :1 , preferably greater than 1 .2:1 , for example in the range 1 .2:1 to 3.5:1 , but is more preferably in the range of 2.0:1 to 3.5:1 , especially 2.0:1 to 2.75:1 for methanol synthesis catalysts and in the range of 1.2:1 to 1.9:1 for water-gas shift catalysts. In the methanol synthesis catalysts, the catalyst preferably contains 20-30% by weight zinc oxide. In water gas shift catalysts the zinc oxide content may be in the range 25-45% by weight, preferably 25-35%

[0038] 20 by weight.

[0039] The catalyst contains alumina, which may be in an amount in the range 5 to 20% by weight. In methanol synthesis catalysts, the alumina content may be in the range 5 to 15% by weight, preferably 8 to 11 % by weight. In water-gas shift catalysts, the alumina content may be as high

[0040] 25 as 15 to 20% by weight. The alumina in the catalyst may be formed by co-precipitation from solutions containing soluble aluminium compounds or may be derived from an alumina sol. The alumina in the catalyst may be present principally as a boehmite AIOOH, and / or as a transition alumina such as gamma alumina or as an aluminate compound such as zinc aluminate.

[0041] The catalyst also contains phosphorus. The amount of phosphorus in the catalyst, expressed as P2O5, is in the range 0.1 to 1.1% by weight, preferably 0.2 to 1.0% by weight, more preferably 0.2 to 0.9% by weight. The phosphorus is believed to exist in the 5+ oxidation state and may be present as an oxyacid of phosphorus or its salt, or an oxysalt of phosphorus or a

[0042] 35 phosphorus oxide. The phosphorus may be dispersed on the surface of the catalyst but is preferably associated with the zinc oxide component and / or the alumina component of the catalyst. The Applicants have found that the replacement of the alumina with phosphorus oxide in aforesaid US4547482 and JPS6097048(A), or the use of phosphorus at high levels in P102379

[0043] 4 the aforesaid CN110935478A creates catalysts that demonstrate poorer activity and stability than the catalysts of the present invention.

[0044] The properties of the calcined catalyst, especially where the catalyst is for methanol synthesis,

[0045] 5 may be further enhanced by the addition of one or more promoter compounds selected from compounds of Mg, Si, Co, Mn, V, Ti, Zr or rare earths, preferably one or more of Mg, Si, and Zr. The Applicant has found an unexpected benefit when the catalyst additionally contains compounds of silicon and / or magnesium. Silicon compounds may be included in the catalyst at low levels in the range of 0.05 to 3.0% by weight, preferably 0.2 to 1 .5% by weight, more preferably 0.3 to 1.2% by weight, in each case expressed as SiC>2. The Si:AI atomic ratio may be in the range of 0.03 to 0.3:1 . Alternatively, or in addition, the catalyst may contain magnesium. The catalyst may contain magnesium in an amount in the range of 0.2 to 5% by weight, expressed as MgO. Accordingly, the catalyst may suitably consist essentially of oxides of copper, zinc, aluminium, phosphorus, magnesium and / or silicon.

[0046] 15

[0047] The catalyst typically has a copper surface area > 37m2 / g catalyst, preferably > 40m2 / g catalyst, more preferably > 45m2 / g catalyst and most preferably > 50m2 / g catalyst. Copper surface areas up to about 60m2 / g catalyst may be achieved. These surface areas are suitably determined on the catalyst as received. The copper surface area may be readily established

[0048] 20 by using reactive frontal chromatography as described in EP-A-0202824. A particularly suitable method is as follows: catalyst shaped units are crushed and sieved to a particle size of 0.6 to 1 .00mm. About 2.0 g of the crushed material is weighed into a stainless steel tube and heated to 68°C and purged with helium for 2 minutes. Then, the catalyst is reduced by heating it in a flow of 5%vol H2 in helium, at 4°C I min up to 230°C and holding at this temperature for

[0049] 25 30 minutes until fully reduced. The reduced catalyst is cooled to 68°C under helium. The reduced catalyst then has a 2.5%vol N2O in helium gas mixture passed over the catalyst. The evolved gases are passed through a gas chromatograph and the N2 evolution is measured. From this, the copper surface area per gram of un-reduced catalyst may be calculated.

[0050] The BET surface area of the shaped catalyst, as determined by nitrogen physisorption, may be > 105m2 / g, and is preferably > 107m2 / g, more preferably > 109m2 / g, most preferably > 110m2 / g, and especially > 115m2 / g. BET surface areas up to about 140m2 / g may be achieved. The BET surface areas are suitably determined on a crushed pellet. The BET surface areas on unshaped powders are higher, and may be in the range 120 to 160m2 / g.

[0051] 35

[0052] In the catalyst, the zinc oxide, alumina, phosphorus, and promoter oxide if present, are not substantially reduced to metal under the carbon oxide conversion process conditions and are typically present as the oxides in the catalyst. The copper oxide may be reduced either ex-situ or in-situ to form catalytically active copper metal crystallites before use. P102379

[0053] 5

[0054] The oxidic copper-containing catalyst may be prepared by:

[0055] (i) forming, in an aqueous medium, an intimate mixture comprising a co-precipitate of copper, zinc, aluminium and phosphorus compounds,

[0056] 5 (ii) recovering, washing and drying the intimate mixture to form a dried composition, and

[0057] (iii) calcining and shaping the dried composition to form the catalyst.

[0058] In one embodiment, the method comprises forming, in an aqueous medium, an intimate mixture comprising a co-precipitate of copper and zinc compounds, with alumina and phosphorus wherein the alumina is provided by an alumina sol. The co-precipitate may be prepared by mixing an acidic aqueous solution containing copper and zinc compounds in the appropriate ratio and combining this with an aqueous alkaline precipitant solution. The copper and zinc compounds are preferably nitrates. The alumina sol may be added to the precipitation vessel separately from the acidic metal solution or alkaline precipitant solution as this has been

[0059] 15 found to enhance the properties of the catalyst. Alumina sols are available commercially or may be prepared by known methods. The alumina concentration in the sol may be 30 to 200 g / litre. Particularly suitable alumina sols comprise dispersions of colloidally dispersed boehmite having a D50 average particle size in the range of 5 to 200 nm, preferably 5 to 100 nm, more preferably 5-50 nm, when dispersed. Such sols are commercially available. The acidic solution

[0060] 20 is typically a mixed metal nitrate solution comprising copper(ll) nitrate and zinc (II) nitrate. Phosphorus may be added to the acidic or precipitant solutions or co-precipitate as a phosphorous acid or a soluble phosphate salt. Compounds of promoters, such as nitrates of Mg or Zr, may be included in the acidic solution of copper and zinc. A water-soluble silicon compound, or a silica sol, may also be included. The alkaline precipitant may be an alkali-

[0061] 25 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 a potassium precipitant is preferred as we have found it to be more readily removed by washing than sodium from the precipitated composition. The precipitation may be performed at temperatures in the range of 10 to 80°C, but is preferably performed at elevated temperature, i.e. in the range 40 to 80°C, more preferably 50 to 80°C, especially 60 to 80°C. The acidic and alkaline solutions may be added one to another in a precipitation vessel but are preferably added simultaneously to the precipitation vessel such that the pH in the precipitation vessel is maintained between 6 and 9, preferably between 6 and 7 after which the resulting co- precipitate slurry is aged at a temperature in the range of 10 to 80°C, preferably in the range of

[0062] 35 40 to 80°C, more preferably 50 to 80°C, especially 60 to 80°C, to form crystalline compounds, preferably crystalline hydroxycarbonate compounds, of copper and zinc.

[0063] In another embodiment, the catalyst may be prepared by steps comprising: (a) combining an acidic copper-containing solution with a basic precipitant solution in a first precipitation step to P102379

[0064] 6 form a first precipitate, (b) combining an alkali metal aluminate solution with an acidic solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further precipitate mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst,

[0065] 5 wherein at least 70% by weight of the copper in the catalyst is present in the first precipitate and a phosphorous compound is included in the first precipitation step, the second precipitation step and / or the precipitate mixing step. The basic precipitant may be an aqueous solution of an alkali-metal carbonate or bicarbonate, an alkali metal hydroxide or a mixture thereof. Ammonium hydroxide may also be used. The acidic copper-containing solution in the first precipitation step may suitably comprise copper nitrate. If desired, zinc compounds and promoter compounds, again suitably nitrates, may also be included. The alkaline precipitant preferably consists of an alkali metal carbonate so that copper hydroxycarbonate materials are precipitated. Potassium or sodium precipitants may be used. Sodium carbonate or potassium carbonate solutions are preferred. The basic precipitant solution may further comprise one or

[0066] 15 more of the above promoter metals. The pH of the basic precipitant solution may be in the range 9-13. The acidic copper-containing solution and basic precipitant solutions may be added one to another in a first precipitation vessel but are preferably added simultaneously to the first precipitation vessel such that the pH in the first precipitation vessel is maintained between 6 and 9, preferably between 6 and 7. The precipitation step forms a precipitate, which

[0067] 20 is desirably mixed to form a slurry. If desired, the co-precipitate slurry may be aged to homogenise the precipitate and ripen crystalline materials. The precipitation and ageing may be performed at temperatures in the range of 10 to 80°C, but is preferably performed at elevated temperature, i.e. in the range 40 to 80°C, more preferably 50 to 80°C, especially 60 to 80°C. This method further requires a step (b) of combining an alkali metal aluminate solution

[0068] 25 with an acidic solution in a second precipitation step to form a second precipitate. The alkali metal aluminate is suitably sodium aluminate or potassium aluminate. Sodium aluminate is preferred. The acidic solution in the second precipitation may be formed using a suitable acid, such as nitric acid. If desired promoter metal compounds, again suitably nitrates, may be included in the acidic solution. The pH of the acidic solution may be in the range 0.5-4. The acidic solution may contain one or more copper compounds, one or more zinc compounds and / or one or more promoter metal compounds as discussed above. If desired, one or more acidic aluminium compounds may also be included. Preferably the second precipitation step consists of combining the alkali metal aluminate solution, such as sodium aluminate solution, with an acidic solution, especially a nitric acid solution, optionally containing one or more promoter

[0069] 35 compounds, such as magnesium nitrate and / or zirconyl nitrate. The acidic solution and alkali metal aluminate solution may be added one to another in a second precipitation vessel. The final precipitation pH is preferably between 3 and 9, more preferably between 3 and 8. Alternatively, the acidic solution and alkali metal aluminate solution may be added simultaneously to the second precipitation vessel such that the pH in the second precipitation P102379

[0070] 7 vessel is maintained between 3 and 9, preferably between 3 and 8. Ageing of the precipitate slurry may, if desired, be carried out using the methods described above for the first precipitate. The second precipitation step is also preferably mixed or agitated thereby forming a slurry of the precipitate. This method further requires a step (c) of contacting the first and second

[0071] 5 precipitates together in a further precipitate mixing step to form a catalyst precursor. This step may be performed by recovering the precipitates from the first and second precipitation steps, for example by filtration or centrifuge, and then combining the recovered precipitates in a slurry of water or other suitable solvent. It is more convenient, however, to combine the slurries of the first and second precipitates together in a mixing vessel. It is preferred that neither of the precipitates is separated and washed prior to the combining step (c).

[0072] In yet another embodiment, the catalyst may be prepared by steps comprising: (a) combining an acidic copper-containing solution with a first basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an acidic aluminium-containing solution, further

[0073] 15 comprising one or more metal compounds selected from copper compounds, zinc compounds and promoter compounds, with a second basic precipitant solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein a phosphorus compound is

[0074] 20 included in the first precipitation step, the second precipitation step and / or the precipitate mixing step. The acidic copper containing solution may be formed by dissolving copper or copper oxide in a suitable acid, such as nitric acid, or by dissolving one or more soluble copper compounds in water and adding acid if necessary. The one or more copper compounds may be selected from copper (II) nitrate, copper (II) acetate or other water-soluble copper

[0075] 25 compounds or salts. Copper (II) nitrate is preferred. The acidic copper-containing solution may usefully contain other components suitable for inclusion in copper catalysts. In particular the acidic copper-containing solution may contain one or more soluble zinc compounds. The one or more zinc compounds may be selected from zinc (II) nitrate, zinc (II) acetate or other water- soluble zinc compounds or salts. The acidic copper-containing solution may further comprise one or more promoter compounds. An acid, preferably nitric acid, may be added to the acidic copper-containing solution if desired. The first basic precipitant solution may comprise an alkali metal hydroxide or ammonium hydroxide, but this is less preferred and desirably the first basic precipitant solution preferably consists an alkali metal carbonate or bicarbonate, or mixtures thereof, so that copper hydroxycarbonate materials are precipitated. Sodium carbonate or

[0076] 35 potassium carbonate solutions are preferred. The first basic precipitant solution may further comprise one or more of promoter metals. The acidic copper-containing solution and first basic precipitant solutions may be added one to another in a first precipitation vessel but are preferably added simultaneously to the first precipitation vessel such that the pH in the first precipitation vessel is maintained between 6 and 9, preferably between 6 and 7. The P102379

[0077] 8 precipitation step forms a precipitate, which is desirably mixed to form a slurry. If desired, the co-precipitate slurry may be aged to homogenise the precipitate and ripen crystalline materials. Ageing of the co-precipitate slurry may be carried out in a batch or semi-continuous procedure in a first ageing vessel whereby the aqueous slurry of the precipitated material is held in one or

[0078] 5 more stirred vessels for a period of time. The method further requires a step (b) combining an acidic aluminium-containing solution, further comprising one or more metal compounds selected from copper compounds, zinc compounds and promoter compounds, with a second basic precipitant solution in a second precipitation step to form a second precipitate. The acidic aluminium-containing solution may be formed by dissolving one or more aluminium compounds in water and adding acid if necessary. The one or more aluminium compounds may be selected from aluminium nitrate, aluminium acetate or other acidic water-soluble aluminium compounds or salts. Aluminium nitrate is preferred. The acidic aluminium-containing solution contains one or more other components suitable for inclusion in copper catalysts. In particular, the acidic aluminium-containing solution may contain one or more metal compounds selected

[0079] 15 from copper compounds, zinc compounds and promoter compounds. Whereas one or more copper compounds may be included in the second precipitation step it is preferred to include one or more zinc compounds and / or one or more promoter compounds, such as one or more magnesium compounds, in the acidic aluminium-containing solution. An acid, preferably nitric acid, may be added to the acidic aluminium-containing solution if desired. In the second

[0080] 20 precipitation step (b), one or more metal compounds selected from copper compounds, zinc compounds and promoter compounds are co-precipitated with the aluminium. The second basic precipitant solution used in the second precipitation step may comprise alkali metal hydroxide, or an alkali metal carbonate, bicarbonate or mixtures thereof. Preferably the second basic precipitant solution consists of an alkali metal hydroxide. The alkali metal hydroxide may

[0081] 25 be sodium or potassium hydroxide or mixtures thereof. Preferably the second precipitation step consists of combining an aqueous acidic aluminium-containing solution, such as aluminium nitrate solution, containing one or more zinc compounds, such as zinc nitrate, and / or promoter compounds, such as magnesium nitrate, sodium silicate and / or zirconyl nitrate, with an aqueous second basic precipitant solution, especially a sodium or potassium hydroxide solution. The acidic aluminium-containing solution and second basic precipitant solution may be added one to another in a second precipitation vessel but are preferably added simultaneously to a second precipitation vessel such that the pH in the second precipitation vessel is maintained between 5 and 9, preferably between 6 and 8. The second precipitation step is preferably mixed or agitated thereby forming a slurry of the precipitate. Optional ageing

[0082] 35 of the precipitate slurry may be carried out using the methods described for the first precipitate. Ageing of the second precipitate is preferred. The precipitation and ageing may be performed at temperatures in the range of 10 to 80°C but is preferably performed in the range 20 to 70°C. The method further requires a step (c) of contacting the first and second precipitates together in a mixing step to form a catalyst precursor. This step may be performed by recovering the P102379

[0083] 9 precipitates from the first and second precipitation steps, for example by filtration or centrifuge, and then combining the recovered precipitates in a slurry of water or other suitable solvent. It is more convenient, however, to combine the slurries of the first and second precipitates together in a mixing vessel. It is preferred that neither of the precipitates is separated and

[0084] 5 washed prior to the combining step (c).

[0085] In yet another embodiment an acidic solution comprising compounds of copper, zinc, aluminium and phosphorus are precipitated in a single precipitation using a basic precipitant solution, followed by ageing, filtering, drying and calcining of the precipitate.

[0086] In each case, ageing of the co-precipitate slurries may be carried out in a batch or semi- continuous procedure whereby the aqueous slurry of the precipitated material is held in one or more stirred vessels for selected periods of time. Alternatively, the co-precipitate slurry may be aged in a pulse-flow reactor as described in W02008 / 047166, which is herein incorporated by

[0087] 15 reference. The reaction and after-treatment conditions of the co-precipitate slurries can be chosen to produce crystalline compounds, for example of the Manasseite, Rosasite, Aurichalcite or Malachite type. The co-precipitation and ageing are preferably operated to produce malachite [Cu2(CC>3)(OH)2], smithsonite [ZnCCh] and / or zincian malachite [(Cu / Zn)2(CC>3)(OH)2] phases, which may be determined by XRD.

[0088] 20

[0089] In each case the phosphorus may be added to the acidic metal solution, the alkaline precipitant solution or to the co-precipitate. The phosphorus may therefore be added using a suitable soluble phosphorus compound, such as an oxyacid of phosphorus or its salt. Phosphoric acid or sodium phosphate may be used.

[0090] 25

[0091] The one or more promoters selected from compounds of Mg, Si, Co, Mn, V, Ti, Zr may, when present in the catalyst, be added to the acidic metal solution, the alkaline precipitant solution or to the co-precipitate. The transition metals may be added as soluble metal nitrates. Magnesium nitrate and zirconyl nitrate are particularly preferred compounds that may be added to the acidic solution or co-precipitate. Where present, the silica in the catalyst may be 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 organo-silicate. For example, a silica sol may be added to the acidic metal solution and / or the alumina sol, when used, and / or added to the precipitation vessel and / or the ageing vessel. Alternatively, an alkali metal silicate may be

[0092] 35 added to the alkaline precipitant solution and / or the alumina sol, where used, and / or to the precipitation and / or ageing vessel. P102379

[0093] 10

[0094] After co-precipitation and ageing, the intimate mixture is recovered, e.g. by separation of the mother liquors using known methods such as filtering, decanting or centrifuging, and is washed to remove residual soluble salts.

[0095] 5 Washing of the intimate mixture may be performed using conventional equipment such as plate-and-frame filter presses, for example by re-slurrying the mixture one or more times in salt- free water, or by dynamic cross-flow filtration using an Artisan thickener or Shriver thickener before recovery. For methanol synthesis catalysts, the alkali metal content of the recovered and dried mixture should desirably be reduced to below 0.2% wt, preferably below 0.1 % wt, calculated as the respective alkali metal oxide on the dried material on a loss-free basis, because alkali metal is detrimental to the performance of the catalyst.

[0096] The recovered intimate mixture is dried to form a dried composition. The drying may comprise heating the damp mixture in discrete stages or continuously over an extended period until the

[0097] 15 maximum temperature is reached. The drying step may be performed at temperatures in the range of 90 to 150°C, preferably 90 to 130°C under air or an inert gas using conventional drying equipment such as in an oven, rotary drier, spray drier or similar equipment.

[0098] The dried composition is typically in the form of a powder. The average particle size (as

[0099] 20 determined by sieve fractions, i.e. the weight-average particle size) may be in the range of 10- 300 |j.m (microns). The dried composition may comprise one or more hydroxycarbonates of copper and zinc, as well as alumina and phosphorus.

[0100] The dried composition is calcined and shaped to form the catalyst. The dried composition may

[0101] 25 be calcined, i.e. heated, to convert the copper and zinc compounds, and any promoter compounds, to their respective oxides prior to shaping or, less preferably, the dried composition may be formed into shaped units before calcination. This latter method is less preferred because the calcination of shaped units generally reduces their strength and makes it more difficult to control pellet density. In the present invention, the calcination may be performed at temperatures in the range of 275 to 450°C preferably 275 to 400°C, more preferably 275 to 350°C. Lower temperatures provide lower pellet stabilities, whereas higher temperatures significantly reduce the initial activity created by the high copper dispersion. Calcination may be performed under air or an inert gas such as nitrogen, but air or another free-oxygen-containing gas is preferred. The calcined product is typically in the form of a

[0102] 35 powder.

[0103] The shaped units are preferably pellets. The dried or calcined powder may therefore be subjected to pelleting, optionally after pre-compacting the powder, which can improve the pelleting process. The pellet may suitably be a cylindrical pellet. Cylindrical pellets for carbon P102379

[0104] 11 oxide conversion processes suitably have a diameter in the range of 2.5 to 10 mm, preferably 3-10 mm and an aspect ratio (i.e. length I diameter) in the range of 0.5 to 2.0. Alternatively, the shaped unit may be in the form of rings. In a particularly suitable embodiment, the shaped unit is in the form of a cylinder having two or more, preferably 3 to 7 grooves running along its

[0105] 5 length. Suitable domed cylindrical shapes having one or more flutes are described in our WO 2010 / 029325, herein incorporated by reference.

[0106] Pellets, particularly cylindrical pellets with flat or domed ends as described above, are desirably made with pellet densities in the range of 1 .8 to 2.4 g / cm3, preferably 1 .9 to 2.3 g / cm3. The pellet density may readily be determined by calculating the volume from the pellet dimensions and measuring its weight. As the density is increased, the interstitial volume in the shaped units is reduced, which in turn reduces the permeability of reacting gases. Therefore, for densities > 2.4 g / cm3the reactivity of the catalyst may be less than optimal, despite the high volumetric copper content. For densities < 1.8 g / cm3the crush strengths may be insufficient for

[0107] 15 long-term use in modern carbon-oxide conversion processes.

[0108] The invention further includes a carbon oxides conversion process, which comprises reacting a carbon oxide containing process gas containing at least one of carbon monoxide and carbon dioxide and additionally containing hydrogen and / or steam, in the presence of the catalyst.

[0109] 20 Accordingly, the term “carbon oxides” herein includes at least one of carbon monoxide and carbon dioxide. The catalyst may be pre-activated in-situ by exposing it to a reducing gas stream, preferably comprising hydrogen, to convert the copper oxide into elemental copper. Thus, the invention preferably includes the steps of (i) activating the catalyst by contacting it with a reducing gas stream and (ii) reacting a carbon oxide containing process gas containing

[0110] 25 at least one of carbon monoxide and carbon dioxide and additionally containing hydrogen and / or steam, in the presence of a catalyst to form a product stream. Activation may be performed using a hydrogen containing gas, including synthesis gas comprising hydrogen and carbon oxides, at temperatures above 80°C and at pressures in the range of 1-50 bar g. The maximum reduction temperature is desirably 150 to 300°C.

[0111] The invention includes processes using the catalyst, in particular:

[0112] A. Methanol synthesis in which a gas mixture containing one or both carbon oxides (i.e. carbon monoxide and / or carbon dioxide) and hydrogen is passed over the 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 a

[0113] 35 space velocity in the range of 500-20000 h-1. The process can be on a once-through or a recycle basis and can involve cooling by indirect heat exchange with surfaces in contact with the reacting gas, or by subdividing the catalyst bed and cooling the gas between the beds by injection of cooler gas. For this process, the catalyst preferably contains copper, zinc oxide and optionally magnesia, with alumina and phosphorus. The catalysts may be used in P102379

[0114] 12 methanol synthesis processes in which natural gas is steam reformed and / or autothermally reformed with oxygen to produce a synthesis gas containing carbon monoxide, carbon dioxide and hydrogen, or in processes where the synthesis gas is richer in carbon monoxide and is derived by the gasification of coal or biomass or municipal waste. The catalyst may be of

[0115] 5 particular use in methanol synthesis processes using hydrogen and CC>2-rich feed gases, i.e. feed gases where the CO2 source contains at least 50%, or at least 75%, or at least 90% or at least 99% CO2 by volume. CC>2-rich feed gases create higher water partial pressures in the reactor than conventional synthesis gases and the catalysts of the present invention have been found to be surprisingly effective and stable, despite possessing oxidic phosphorus that is more water-soluble than metal oxide promoters. The Applicant has found the catalysts to be surprisingly effective for synthesis gas feeds consisting essentially of hydrogen and carbon dioxide. The hydrogen may be recovered from any source, such as from a conventional hydrogen plant or, preferably, from the electrolysis of water. The carbon dioxide may be from any source and may be recovered from air, water, synthesis gases, waste gases, such as

[0116] 15 combustion gases, landfill gas, biogas, or from a CO2 storage facility or pipeline.

[0117] B. Modified methanol synthesis in which the catalyst contains also free alumina of surface area 50-300 m2g-1, or another acidic catalyst, so that the synthesis product is relatively rich in dimethyl ether. Temperatures, pressures and space velocities are similar to those for methanol

[0118] 20 synthesis but the synthesis gas may contain hydrogen and carbon monoxide in a molar ratio of less than 2.

[0119] C. Low temperature shift reaction in which a gas containing carbon monoxide (preferably under 4% v / v on a dry basis) and steam (in which the steam to total dry gas molar ratio is typically in

[0120] 25 the range of 0.3 to 1 .5) is passed over the catalyst in an adiabatic fixed bed at an outlet temperature in the range of 200 to 300°C at a pressure in the range of 15-50 bar abs. Usually the inlet gas is the product of "high temperature shift" in which the carbon monoxide content has been decreased by reaction over a high temperature shift catalyst, such as an iron catalyst or zinc aluminate catalyst, at an outlet temperature in the range of 400 to 500 °C, followed by cooling by indirect heat exchange. The outlet carbon monoxide content from the low temperature shift step is typically in the range of 0.1 to 1 .0%, especially under 0.5% v / v on a dry basis.

[0121] D. Medium temperature shift in which the gas containing carbon monoxide and steam is fed at

[0122] 35 a pressure in the range of 15-50 bar abs to the catalyst at an inlet temperature typically in the range of 200 to 240°C although the inlet temperature may be as high as 280°C, and the outlet temperature is typically up to 300°C but may be as high as 360°C. These conditions are more severe than in B, such that the new catalyst is expected to be especially advantageous. P102379

[0123] 13

[0124] E. Isothermal temperature shift with heat exchange, in which the reaction in the catalyst bed occurs in contact with heat exchange surfaces. The coolant conveniently is water under such a pressure such that partial, or complete, boiling takes place. A suitable pressure is 15 to 50 bar abs and the resulting steam can be used, for example, to drive a turbine or to provide process

[0125] 5 steam for shift, or for an upstream stage in which the shift feed gas is generated. The water can be in tubes surrounded by catalyst or vice versa.

[0126] F. Methanol reforming in which a gaseous methanol stream is combined with steam and / or carbon dioxide and subjected to reaction, typically at temperatures in the range of 250 to 360°C and at pressures typically in the range of 10 to 30 bar abs, over the catalyst to generate a gas mixture containing hydrogen and carbon oxides. The hydrogen may be recovered from the gas mixture using conventional separation methods such as pressure-swing adsorption or hydrogen-permeable membranes.

[0127] 15 The present invention is particularly suitable for methanol synthesis catalysts and low- temperature shift catalysts.

[0128] The invention is now further described by reference to the following Examples.

[0129] 20 In the Examples with one precipitation, unless otherwise stated, the catalysts were prepared at a 2-6 litre scale by simultaneous addition of an aqueous mixed metal nitrate solution, an alkali metal precipitant solution and an aqueous alumina sol dispersion to a 1 L stirred precipitation vessel held at 60 to 70 °C. Ageing of the co-precipitate slurry was performed in a separate stirred vessel for up to 3 hours, at 65 to 75 °C.

[0130] 25

[0131] In the Examples with two precipitations using a basic Al source, unless otherwise stated, first precipitates were prepared at a 2-6 litre scale by simultaneous addition of an aqueous mixed metal nitrate solution, containing Cu and optionally other metals, and an aqueous alkali metal carbonate solution to a stirred precipitation vessel held at 60 to 70 °C. The first precipitates were unaged. Second precipitates were prepared at a 0.1-2 litre scale by addition of an aqueous nitric acid solution, optionally containing dissolved salts of a metal or metals, to an aqueous sodium aluminate solution in a 0.5-3 L stirred precipitation vessel held at 65 to 75 °C. Ageing of the slurries of the second precipitates was performed in a stirred vessel for up to 1 hour, at 65 to 75 °C. The first and second slurries were combined and mixed in an 3-8 litre

[0132] 35 vessel for up to 2 hours, at 65 to 75 °C.

[0133] In the Examples with two precipitations using an acidic Al source, unless otherwise stated, first precipitates were prepared at a 2-6 litre scale by simultaneous addition of an aqueous mixed metal nitrate solution, containing Cu and optionally other metals, and an aqueous alkali metal P102379

[0134] 14 carbonate solution to a stirred precipitation vessel held at 60 to 70 °C. The first precipitates were unaged. Second precipitates were prepared at a 0.1-2 litre scale by simultaneous addition of an aqueous mixed metal nitrate solution, containing Al and optionally other metals, and an aqueous alkali metal hydroxide solution to a stirred precipitation vessel held at 45 to 75

[0135] 5 °C. Ageing of the slurries of the second precipitates was performed in a separate stirred vessel for up to 2 hours, at 45 to 75 °C. The first and second slurries were combined and mixed in a 3-8 litre vessel for up to 2 hours, at 65 to 75 °C.

[0136] Phosphorus and optionally silicon were added to the catalyst by various means at different points in the preparation process. The aged precipitate slurries were filtered and washed with demineralised water. Drying and calcination of the washed precipitate was, unless otherwise stated, carried out at 110 °C and 290-330 °C respectively. The resulting powders were compacted into a shaped unit, which was subsequently crushed into grit particles suitable for testing.

[0137] 15 The alumina sol used was an aqueous sol of a dispersible boehmite, with an AIOOH content of 82-92 wt.%, a Dso particle size of 5-50 nm and a pH of 3.5-4.0. The silica sol used was an aqueous sol of silica, with a silica content of 20-21 wt.%, a Dso particle size of 10-20 nm and a pH of 2-4. The sodium phosphate used was sodium phosphate, dibasic, dihydrate (Thermo Fisher Scientific). The phosphoric acid used was pure phosphoric acid (Thermo Fisher

[0138] 20 Scientific). The sodium silicate used was sodium metasilicate nonahydrate (Sigma Aldrich).

[0139] Unless otherwise stated, in all cases the weight percentages of the metal oxides in the catalyst are determined on a loss-free basis. A particularly suitable method for determining the metal oxide content on a loss-free basis is to heat the catalyst to 900°C for 2 hours in air to remove

[0140] 25 volatiles before measuring the metal oxide contents. The heat-treated catalyst may be stored under anhydrous conditions. The metal oxide content of the catalysts may be determined using any suitable elemental analysis technique, such as X-ray fluorescence spectroscopy (XRF) using known techniques.

[0141] BET surface areas were determined on the crushed pellet grit, after drying, by nitrogen physisorption using a Micromeritics 2420 ASAP physisorption analyser in accordance with ASTM Method D 3663-03; Standard Test for Surface Area. Nitrogen was used as the adsorbate and the measurements carried out at liquid nitrogen temperature (77K). The cross- sectional area of a nitrogen molecule was taken as 16.2A2. Samples were outgassed prior to

[0142] 35 analysis by purging with dry nitrogen gas for a minimum of 1 hour at an optimal temperature. Five relative pressure / volume data pairs were obtained over the relative pressure region of 0.05 to 0.20 P / Po inclusive. The equilibration time for each point was 10 seconds. P102379

[0143] 15

[0144] Copper surface areas were determined using reverse frontal chromatography as follows: catalyst pellets were crushed and sieved to a particle size of 0.6 to 1 .00mm. About 2.0 g of the crushed material was weighed into a stainless steel tube and heated to 68°C and purged with helium for 2 minutes. Then, the catalyst was reduced by heating it in a flow of 5%vol H2 in

[0145] 5 helium, at 4°C I min up to 230°C and holding at this temperature for 30 minutes until fully reduced. The reduced catalyst was cooled to 68°C under helium. The reduced catalyst then had a 2.5%vol N2O in helium gas mixture passed over the catalyst. The evolved gases were passed through a gas chromatograph and the N2 evolution was measured. From this, the copper surface area per gram of discharged catalyst was calculated.

[0146] Malachite crystal sizes of dried intermediates were determined from powder XRD patterns. These were collected on a Bruker D8 diffractometer equipped with a Gbbel mirror, Lynxeye detector and a copper x-ray tube . Phase identification was completed using the Bruker EVA v5.1 .0.5 software. Crystallite size values were estimated using Bruker Topas v6. In the Rietveld method the usual parameters (sample displacement, scale factors, background

[0147] 15 coefficients, unit cell parameters and peak shape) were refined. Atomic positions were fixed and not refined. Reported crystallite size values were obtained from an integral breadth based LVol calculation using Lorentzian and Gaussian type component convolutions.

[0148] Example 1

[0149] 20 An oxidic catalyst with the molar ratio Cu: Zn: Al: Mg: P of 2.7: 1 .0: 0.6: 0.1 : 0.02 and a copper oxide content of 64.4 wt.% was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a potassium carbonate solution containing sodium phosphate, with simultaneous addition of a mixture of an alumina sol to the precipitation vessel, at a pH of 6.4-6.9 and a temperature between 60-70 °C. The resulting

[0150] 25 precipitate was aged for up to 3 hours at 65-75 °C, filtered, washed with demineralised water, dried and calcined in air at 290-310 °C for 6 hours. The resulting powder was compacted into a shaped unit.

[0151] Example 2

[0152] An oxidic catalyst with the molar ratio Cu: Zn: Al: P of 2.7: 1 .0: 0.7: 0.03 and a copper oxide content of 65.7 wt.% was prepared. In a first precipitation step, a mixed metal solution comprising nitrates of copper and zinc was co-precipitated with a sodium carbonate solution at a pH of 6.5-7.0 and a temperature of 60-70°C to form a first precipitate slurry. In a second precipitation step, a mixed metal solution comprising nitrates of aluminium and zinc, which

[0153] 35 contained phosphoric acid, was precipitated with a sodium hydroxide solution at a pH of 6.7-7.2 and a temperature of 65-75°C to form a second precipitate slurry, and the second precipitate slurry subsequently aged at 60-70 °C for up to 2 hours. The second precipitate slurry was added to the first precipitate slurry, and the mixture was stirred at 65-75 °C with stirring for up to 1 hour. The resulting catalyst precursor slurry was dewatered, washed with demineralised P102379

[0154] 16 water, then dried and calcined in air at 290-310 °C for 6 hours. The first precipitate contained 84 wt.% of the total zinc in the calcined catalyst. The second precipitate contained 16 wt.% of the total zinc in the calcined catalyst. The resulting powder was compacted into a shaped unit.

[0155] 5 Example 3

[0156] An oxidic catalyst with the molar ratio Cu: Zn: Al: P of 2.7: 1.0: 0.6: 0.02 and a copper oxide content of 65.0 wt.% was prepared. In a first precipitation step a mixed metal solution comprising nitrates of copper and zinc was co-precipitated with a sodium carbonate solution and a sodium phosphate solution at a pH of 6.7-7.0 and a temperature of 60-70 °C to form a first slurry. In a second precipitation step a nitric acid solution was added to a solution of sodium aluminate to form a precipitate, which was aged at a pH of 6.2-6.8 and a temperature of 60-70 °C for up to 2 hours to form a second slurry. The precipitate slurries were mixed and further aged for up to 1 .5 hours at 65-75 °C, then dewatered, washed with demineralised water, dried and calcined in air at 290-310 °C for 6 hours. The resulting powder was compacted into a

[0157] 15 shaped unit.

[0158] Example 4

[0159] An oxidic catalyst with the molar ratio Cu: Zn: Al: Mg: P: Si of 2.8: 1 .0: 0.7: 0.1 : 0.01 : 0.01 and a copper oxide content of 65.0 wt.% was prepared by co-precipitation of a mixed metal nitrate

[0160] 20 solution comprising nitrates of copper, zinc and magnesium with a potassium carbonate solution containing sodium phosphate and sodium silicate, with simultaneous addition of a mixture of an alumina sol to the precipitation vessel, at a pH of 6.4-6.9 and a temperature between 60-70 °C. The resulting precipitate was aged for up to 3 hours at 65-75 °C, filtered, washed with demineralised water, dried and calcined in air at 290-310 °C for 6 hours. The

[0161] 25 resulting powder was compacted into a shaped unit.

[0162] Example 5

[0163] An oxidic catalyst with the molar ratio Cu: Zn: Al: Mg: P: Si of 2.7: 1 .0: 0.7: 0.07: 0.02: 0.02 and a copper oxide content of 63.7 wt.% was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper, zinc and magnesium with a potassium carbonate solution containing sodium phosphate and sodium silicate, with simultaneous addition of a mixture of an alumina sol to the precipitation vessel, at a pH of 6.4-6.9 and a temperature between 60-70 °C. The resulting precipitate was aged for up to 3 hours at 65-75 °C, filtered, washed with demineralised water, dried and calcined in air at 290-310 °C for 6 hours. The

[0164] 35 resulting powder was compacted into a shaped unit.

[0165] Example 6

[0166] An oxidic catalyst with the molar ratio Cu: Zn: Al: Mg: Si: P of 2.7: 1 .0: 0.6: 0.07: 0.01 : 0.02 and a copper oxide content of 65.0 wt.% was prepared. In a first precipitation step, a mixed metal P102379

[0167] 17 solution comprising nitrates of copper, zinc and magnesium was co-precipitated with a sodium carbonate solution containing sodium phosphate and sodium silicate, at a pH of 6.5-7.0 and a temperature of 60-70°C to form a first precipitate slurry. In a second precipitation step, a mixed metal solution comprising nitrates of aluminium and zinc was precipitated with a sodium

[0168] 5 hydroxide solution at a pH of 5.1-5.6 and a temperature of 45-55°C to form a second precipitate slurry, and the second precipitate slurry subsequently aged at 45-55 °C for up to 2 hours. The second precipitate slurry was added to the first precipitate slurry, and the mixture was stirred at 65-75 °C with stirring for up to 1 hour. The resulting catalyst precursor slurry was dewatered, washed with demineralised water, then dried and calcined in air at 290-310 °C for 6 hours. The first precipitate contained 95 wt.% of the total zinc in the calcined catalyst. The second precipitate contained 5 wt.% of the total zinc in the calcined catalyst. The resulting powder was compacted into a shaped unit.

[0169] Comparative Example 1

[0170] 15 An oxidic catalyst as described in US4788175 with the molar ratio Cu: Zn: Al of 2.6: 1 .0: 0.6 and a copper oxide content of 65.2 wt.% was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper and zinc with a solution of potassium carbonate, with simultaneous addition of an alumina sol to the precipitation vessel, at a pH of 6.3-6.8 and a temperature between 60-70 °C. The resulting precipitate was aged for up to 2 hours at 65 to

[0171] 20 75 °C, filtered, washed with demineralised water, dried and calcined in air at 290 to 310 °C for 6 hours. The resulting powder was compacted into a shaped unit.

[0172] Comparative Example 2

[0173] An oxidic catalyst with the molar ratio Cu: Zn: P of 2.0: 1.0: 0.02 and a copper oxide content of

[0174] 25 65.6 wt.% was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper and zinc with a potassium carbonate solution and a sodium phosphate solution at a pH of 6.3-6.7 and a temperature between 60-70 °C. The resulting precipitate was aged for up to 2 hours at 65-75 °C, filtered, washed with demineralised water, dried and calcined in air at 290-310 °C for 6 hours. The resulting powder was compacted into a shaped unit.

[0175] Comparative Example 3

[0176] An oxidic catalyst with the molar ratio Cu: Zn: Al: P of 2.7: 1 .0: 0.7: 0.1 and a copper oxide content of 63.2 wt.% was prepared by co-precipitation of a mixed metal nitrate solution comprising nitrates of copper and zinc with a potassium carbonate solution containing sodium

[0177] 35 phosphate, with simultaneous addition of a mixture of an alumina sol to the precipitation vessel, at a pH of 6.7-7.0 and a temperature between 60-70 °C. The resulting precipitate was aged for up to 2 hours at 65-75 °C, filtered, washed with demineralised water, dried and calcined in air at 290-310 °C for 6 hours. The resulting powder was compacted into a shaped unit. P102379

[0178] 18

[0179] Comparative Example 4

[0180] An oxidic catalyst with the molar ratio Cu: Zn: Si: Zr: P of 3.4: 1 .0: 5.7: 0.2: 0.04 and a copper oxide content of 37.1 wt.% was prepared following the procedure outlined in CN107721821 Example 2. Silica sol was added to a 1 molar mixed metal solution comprising nitrates of

[0181] 5 copper, zinc and zirconium, which contained phosphoric acid and stirred at 55-60 °C for 5-6 hours, then dried at 90 °C for 4 hours, calcined in air at 550 °C for 5 hours. The resulting powder was compacted into a shaped unit.

[0182] Comparative Example 5

[0183] 10 An oxidic catalyst with the molar ratio Cu: Zn: Al: Zr: Mg: Si: P of 3.3: 1 .0: 5.8: 0.3: 0.04: 0.04: 0.04 and a copper oxide content of 38.9 wt.% was prepared following the procedure outlined in CN107721821 Example 2. Boehmite and silica sol were added to a 1 molar mixed metal solution comprising nitrates of copper, zinc, zirconium and magnesium, which contained phosphoric acid and stirred at 55-60 °C for 5-6 hours, then dried at 90 °C for 4 hours, calcined in air at 550 °C for 5 hours. The resulting powder was compacted into a shaped unit.

[0184] The catalyst properties were as follows:

[0185] 20 P102379

[0186] 19

[0187] Microreactor Testing - Conventional Methanol Conditions

[0188] Each of the catalyst samples were crushed and sieved to a particle size fraction of 0.6 -1 .0 mm. The experiments used a conventional micro-reactor. The crushed catalyst samples were fully reduced with a gas mixture of 2 % v / v hydrogen in nitrogen at 225 °C. A process gas mixture

[0189] 5 with a gas composition of 6 % v / v CO, 6 % v / v CO2, 9 % v / v N2 and 79 % v / v H2 was then introduced over the catalyst samples. The reduced catalyst samples were exposed to the process gas mixture at 225 °C, 40,000 L / hr / kg, 50 barg at the start of life. After a period, catalyst samples were exposed to deactivating conditions over 300 °C to simulate harsh operating conditions and accelerate the deactivation effects. Analysis flow scans of product

[0190] 10 gases were performed at the start of life and after the catalyst had been held at deactivation conditions. Analysis flow scans were performed by varying the mass velocity at 225 °C, 50 barg. An infra-red analyser was used to determine the % v / v concentration of the exit gas streams from the reactors. The analysis flow scan data was used to calculate the relative activity of the test material against a reference catalyst, selected in these experiments to be Comparative Example 1 . The relative activities are calculated from the ratio of the flow rates through each catalyst at constant conversion relative to the flow rate through the standard catalyst.

[0191] The results are set out in the following table:

[0192] 20

[0193] These results demonstrate that the addition of phosphorus to the formulations has increased the stability of the catalysts versus the comparative example 1 . Comparative example 2 shows that similar formulations without alumina perform poorly. Comparative example 3 illustrates that formulations with higher levels of phosphorus also perform poorly. Comparative P102379

[0194] 20 examples 4 and 5 illustrate that formulations with higher levels of alumina or silica also perform poorly.

[0195] Microreactor Testing - CO2 to Methanol conditions

[0196] 5 Each of the catalyst samples were crushed and sieved to a particle size fraction of 0.6 -1 .0 mm. The experiments used a conventional high throughput reactor. The crushed catalyst samples were fully reduced with a gas mixture of 5 mol% hydrogen in nitrogen at 225 °C. A process gas mixture with a gas composition of 1 mol% CO, 22 mol% CO2, 3 mol% N2 , 1 mol% He and 73 mol% H2 was then introduced over the catalyst samples. The reduced catalyst samples were exposed to the process gas mixture at 225 °C, 100,000 L / hr / kg, 50 barg at the start of life. After a period, catalyst samples were exposed to deactivating conditions over 300 °C to simulate harsh operating conditions and accelerate the deactivation effects. Analysis flow scans of product gases were performed at the start of life and after the catalyst had been held at deactivation conditions. Analysis flow scans were performed by varying the mass velocity at

[0197] 15 225 °C, 50 barg. A GC analyser was used to determine the mol% concentration of the exit gas streams from the reactors. The analysis flow scan data was used to calculate the relative activity of the test material against a reference catalyst, selected in these experiments to be Comparative Example 1 . The relative activities are calculated from the ratio of the flow rates through each catalyst at constant conversion relative to the flow rate through the standard catalyst.

[0198] The results are set out in the following table:

[0199] These results demonstrate that the addition of phosphorus to the formulations has increased

[0200] 25 the activity and stability of the catalysts versus the comparative example 1 in this challenging duty.

Claims

P10237921Claims.1 . A catalyst suitable for use in carbon oxide conversion reactions, said catalyst in the form of a shaped unit formed from an oxidic catalyst powder comprising copper oxide, zinc oxide, alumina and phosphorus, having copper oxide content in the range of 30 to 75% by weight, a Cu:Zn atomic ratio greater than 1.1 :1 , and a phosphorus content, expressed as P2O5, in the range of 0.1 to 1.1 % by weight.

2. A catalyst according to claim 1 , wherein the catalyst is a methanol synthesis catalyst comprising copper oxide in an amount in the range 50 to 75% by weight, preferably 60 to 70% by weight.

3. A catalyst according to claim 1 or claim 2, wherein the catalyst contains 20 to 30% by weight zinc oxide or 25 to 45% by weight zinc oxide.

4. A catalyst according to any one of claims 1 to 3, wherein the catalyst contains alumina, in an amount in the range 5 to 20 % by weight.

5. A catalyst according to any one of claims 1 to 4, wherein the amount of phosphorus in the catalyst, expressed as P2O5, is in the range 0.2 to 1 .0% by weight, preferably 0.2 to 0.9% by weight.

6. A catalyst according to any one of claims 1 to 5, wherein the catalyst further comprises one or more promoter compounds selected from compounds of Mg, Si, Co, Mn, V, Ti, Zr or rare earths, preferably one or more of Mg, Si, and Zr.

7. A catalyst according to any one of claims 1 to 6, wherein the catalyst contains compounds of silicon and / or magnesium, preferably silicon in the range of 0.05 to 3.0% by weight, expressed as SiC>2, and / or magnesium in an amount in the range of 0.2 to 5% by weight, expressed as MgO.

8. A catalyst according to any one of claims 1 to 7, wherein the catalysts have a copper surface area > 37m2 / g catalyst, preferably > 40m2 / g catalyst, more preferably > 45m2 / g catalyst, most preferably > 50m2 / g catalyst.

9. A catalyst according to any one of claims 1 to 8, wherein the BET surface area of the catalyst, as determined by nitrogen physisorption, is > 105m2 / g, preferably > 107m2 / g, more preferably > 109m2 / g, most preferably > 110m2 / g, and especially > 115m2 / g.P1023792210. A method for making a catalyst according to any one of claims 1 to 9, comprising the steps of: (i) forming, in an aqueous medium, an intimate mixture comprising a coprecipitate of copper, zinc, aluminium and phosphorus compounds, (ii) recovering, washing and drying the intimate mixture to form a dried composition, and (iii) calcining and shaping the dried composition to form the catalyst.

11. A method according to claim 10, wherein the method comprises forming, in an aqueous medium, an intimate mixture comprising a co-precipitate of copper and zinc compounds, with alumina and phosphorus wherein the alumina is provided by an alumina sol, and wherein the co-precipitate is prepared by mixing an acidic aqueous solution containing copper and zinc compounds and combining this with an aqueous alkaline precipitant solution in a precipitation vessel and wherein the phosphorus may be added to the acidic metal solution, the alkaline precipitant solution or to the co- precipitate.

12. A method according to claim 10, wherein the method comprises: (a) combining an acidic copper-containing solution with a basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an alkali metal aluminate solution with an acidic solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further precipitate mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein at least 70% by weight of the copper in the catalyst is present in the first precipitate and a phosphorous compound is included in the first precipitation step, the second precipitation step or the precipitate mixing step.

13. A method according to claim 10, wherein the method comprises: (a) combining an acidic copper-containing solution with a first basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an acidic aluminium- containing solution, further comprising one or more metal compounds selected from copper compounds, zinc compounds and promoter compounds, with a second basic precipitant solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein a phosphorus compound is included in the first precipitation step, the second precipitation step or the precipitate mixing step.

14. A method according to claim 10, wherein an acidic solution comprising compounds of copper, zinc, aluminium and phosphorus are precipitated in a single precipitation using a basic precipitant solution, followed by ageing, filtering, drying and calcining of the precipitate.P1023792315. A method according to any one of claims 10 to 14, wherein the copper and zinc compounds are nitrates and the alkaline precipitant comprises an alkali metal carbonate, preferably sodium or potassium carbonate.

16. A method according to any one of claims 10 to 15, wherein the phosphorus is included as an oxyacid of phosphorus or its salt, preferably as phosphoric acid or sodium phosphate.

17. A method according to any one of claims 10 to 16, wherein the precipitation is performed at a temperature in the range of 40 to 80°C, preferably 50 to 80°C, especially 60 to 80°C or where the co-precipitate is aged 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.

18. A method according to any one of claims 10 to 17, wherein magnesium nitrate or zirconyl nitrate is included in forming the intimate mixture comprising a co-precipitate of copper, zinc, aluminium and phosphorus compounds.

19. A method according to any one of claims 10 to 18 wherein a silicon compound selected from a silica sol and / or a water-soluble silicon compound, preferably an alkali metal silicate, or an organo-silicate is included in forming the intimate mixture comprising a co-precipitate of copper, zinc, aluminium and phosphorus compounds .

20. A method according to any one of claims 10 to 19, wherein the drying step is performed at a temperature in the range of 90-150°C.21 . A method according to any one of claims 10 to 20, wherein the shaped composition is a cylindrical pellet having a diameter in the range of 2.5 to 10 mm, preferably 3 to 10 mm and an aspect ratio (length I diameter) in the range of 0.5 to 2.0.

22. A method according to any one of claims 10 to 21 , wherein the calcination is performed at a temperature in the range of 275 to 450°C, preferably 275 to 400°C, more preferably 275 to 350°C.

23. A carbon oxides conversion process which comprises reacting a carbon oxide containing process gas containing at least one of carbon monoxide and carbon dioxide and additionally containing hydrogen and / or steam, in the presence of a catalyst according to any one of claims 1 to 9 or prepared according to the method according to any one of claims 10 to 23.P1023792424. A process according to claim 23, wherein the process is selected from methanol synthesis and the water-gas shift reaction.

25. A process according to claim 24, wherein the methanol synthesis is carried out using a synthesis gas feed comprising a CC>2-rich gas and hydrogen, preferably a synthesis gas feed comprising a CO2 gas stream and hydrogen gas stream produced by the electrolysis of water.

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