OXIDIC COMPOSITION

Abstract

An oxidic composition comprising vanadium, tungsten, phosphorus, oxygen and optionally tin, where the molar ratio of phosphorus to the sum total of vanadium, tungsten and any tin in the oxidic composition is in the range from 1.4:1 to 2.4:1.

Claims

1. An oxidic composition, comprising; vanadium, tungsten, phosphorus, oxygen and optionally tin, wherein the molar ratio of phosphorus to the sum total of vanadium, tungsten and any tin in the oxidic composition is in the range from 1.4:1 to 2.4:1.

2. The oxidic composition according to claim 1, wherein the molar ratio of phosphorus to the sum total of vanadium, tungsten and any tin is in the range from 1.8:1 to 2.3:1.

3. The oxidic composition according to claim 1, wherein the molar ratio of vanadium to tungsten in the oxidic composition is in the range from 10:1 to 1:100.

4. The oxidic composition according to claim 1, wherein the oxidic composition comprises not more than 1000 molar ppm, of molybdenum.

5. The oxidic composition according to claim 1, wherein the oxidic composition comprises not more than 1000 molar ppm, of bismuth.

6. The oxidic composition according to claim 1, wherein the oxidic composition comprises not more than 1000 molar ppm, of titanium.

7. The oxidic composition according to claim 1, wherein the oxidic composition comprises tin.

8. The oxidic composition according to claim 7, wherein the molar ratio of vanadium to tin in the oxidic composition is in the range from 100:1 to 1:100.

9. The oxidic composition according to claim 1, further comprising a support material.

10. The oxidic composition according to claim 1, wherein the oxidic composition is a catalyst.

11. The oxidic composition according to claim 1, wherein the oxidic composition is an unsupported catalyst.

12. The oxidic composition according to claim 9, wherein the oxidic composition is a supported catalyst.

13. A process for producing an oxidic composition, comprising: providing a support material; providing an aqueous vanadium solution, an aqueous tungsten solution, an aqueous phosphorus solution and optionally an aqueous tin solution; impregnating the support material with the aqueous vanadium solution and the aqueous tungsten solution and optionally the aqueous tin solution; optionally drying the resulting impregnated material; impregnating the optionally dried material with the aqueous phosphorus solution; optionally drying the resulting impregnated material; calcining the optionally dried material.

14. The process according to claim 13 for producing an oxidic composition; said composition comprising vanadium, tungsten, phosphorus, oxygen and optionally tin, wherein the molar ratio of phosphorus to the sum total of vanadium, tungsten and any tin in the oxidic composition is in the range from 1.4:1 to 2.4:1.

15. The process according to claim 13, wherein the aqueous solutions provided comprise a total of not more than 1000 molar ppm, of molybdenum, not more than 1000 molar ppm, of bismuth and not more than 1000 molar ppm, of titanium.

16. The process according to claim 13, wherein the aqueous vanadium solution comprises vanadium citrate or vanadium oxalate or a mixture thereof, the aqueous phosphorus solution comprises phosphoric acid, the aqueous tin solution comprises tin oxalate, optionally as a mixture with nitric acid, and the aqueous tungsten solution comprises ammonium metatungstate.

17. The process according to claim 13, comprising (i) providing the support material; (ii) providing the aqueous vanadium solution, the aqueous tungsten solution; the aqueous phosphorus solution; (iii) impregnating the support material with the aqueous vanadium solution; (iv) optionally drying the material obtained in (iii); (V) impregnating the material obtained in (iv) with the aqueous tungsten solution; (vi) optionally drying the material obtained in (V); (vii) impregnating the material obtained in (vi) with the aqueous phosphorus solution; (viii) optionally drying the material obtained in (vii); (ix) calcining the material obtained in (viii).

18. The process according to claim 17, wherein (ii) additionally comprises the providing of an aqueous tin solution and the process additionally comprises (a) impregnating the material obtained in (iv) or that obtained in (vii) with the aqueous tin solution; (b) optionally drying the material obtained in (a), where (a) to (b) optionally follow (iv) and precede (V) or follow (vi) and precede (vii).

19. An oxidic composition, obtained or obtainable by a process according to claim 13.

20. A process for preparing acrylic acid from acetic acid and formaldehyde, comprising (i) providing a stream S1 comprising acetic acid and formaldehyde; (ii )contacting stream S1 with an aldol condensation catalyst comprising, preferably consisting of, an oxidic composition according to claim 1 to obtain a stream S2 comprising acrylic acid.

Description

EXAMPLES

[0182] I. Analysis

[0183] 1.1 Gas Chromatography [0184] For analysis of the product stream, an online Agilent 7890A GCMS system was used. [0185] Sampling was effected by a 10-port valve having a 500 L sample loop or 1000 L sample loop. [0186] The analysis parameters can be expressed as follows: [0187] MS/FID: [0188] FFAP 25 m0.32 mm0.5 m, carrier gas He, split 5:1, column flow rate 15 mL/min [0189] TCD: [0190] DB624 3 m0.25 mm1.4 m [0191] Volamine 60 m0.32 mm, carrier gas He, split 5:1, column flow rate 15 mL/min [0192] TCD2: [0193] RTX5 30 m0.32 mm1.0 m [0194] Select permanent gases/CO2 HR carrier gas He, split 2:1, column flow rate: 30 mL/min [0195] The temperature program was selected as follows: [0196] hold at 40 C. for 2.5 min [0197] heat to 105 C. at a heating rate of 20 K/min [0198] heat to 225 C. at a heating rate of 40 K/min [0199] hold at 225 C. for 2.75 min

[0200] II. Chemicals

TABLE-US-00001 Chemical Supplier Purity vanadium(V) oxide Sigma Aldrich >99.6% oxalic acid dihydrate Acros Organics >99% phosphoric acid Acros Organics >85% ammonium metatungstate Sigma Aldrich >99% tin(II) oxalate Merck >98% potassium nitrate Merck >99% lanthanum(III) nitrate hexahydrate Sigma Aldrich >99% bismuth(III) nitrate pentahydrate Sigma Aldrich >99.99% molybdenum oxide Sigma Aldrich >99.5

[0201] II. Preparation of Highly Concentrated Solutions of V.sub.2O.sub.5 in Aqueous Oxalic Acid

[0202] 1.1 Molar Solution of V.sub.2O.sub.5 in Oxalic Acid

[0203] A 2 L three-neck flask was initially charged with 800 mL of aqueous oxalic acid dihydrate solution. While stirring, 1.1 mol of V.sub.2O.sub.5 were added to this solution and heated to 80 C. by means of a heating bath and refluxed. Oxalic acid dihydrate in solid form was then added in portions to the orange-brown suspension and the flask was sealed again. Evolution of gas and foam was observed here (redox reaction between V.sub.2O.sub.5 and oxalic acid). The addition of oxalic acid dihydrate was then repeated until the original suspension had become a deep blue solution. For this purpose, about three times the molar amount of oxalic acid dihydrate was needed (based on the molar amount of V.sub.2O.sub.5). The vanadium was present in the form of a solution of vanadyl oxalate VO(C.sub.2O.sub.4) with a molar concentration of vanadium of 2.2 mol/L. The solution thus obtained was cooled down to room temperature and transferred quantitatively into a 1 L standard flask (rinsing in with demineralized water, DM water). DM water (demineralized water) was used to make it up to 1 liter.

[0204] The mass of vanadium pentoxide to be weighed in (Sigma Aldrich Prod. No.: 221899) was determined by the following formula:

[00001]$m\left(V.Math..Math.2.Math.O.Math..Math.5\right)=\frac{2.Math.M\left(V\right).Math.c.Math.V}{\mathrm{wt}.Math..Math.\%}$ [0205] M(V)=molar mass of V c=concentration of the solution to be prepared [0206] V=batch volume % by wt.=vanadium content of the V.sub.2O.sub.5 (manufacturer's certificate of analysis)

[00002]$m.Math.\left(V.Math..Math.2.Math.O.Math..Math.5\right)=\frac{2.Math.50.94.Math..Math.g.Math.\text{/}.Math.\mathrm{mol}.Math.1.1.Math..Math.\mathrm{mol}.Math.\text{/}.Math.L.Math.1.Math..Math.L}{0.562}=199.41.Math..Math.g$

[0207] III Catalysts

[0208] III.1 General Details

[0209] The ignition loss (LOI hereinafter) of the support was determined beforehand. In this way, the exact content of oxidic components was known and it was possible to correct the starting support weight with this value. It was thus possible to ensure that the desired loading with active components was attained. The LOI of the Q20C support (CARiACT Q20C silica from Fuji Silysia) was 2.95%.

[0210] The impregnations were conducted to 100% of the water uptake (hereinafter 100% ICW) with mixed solutions of DM water and active component.

[0211] The loadings in the case of supported catalysts were given in % by weight on support. This means that, for example, for a 9.36V/11.3P/Q20C catalyst, for the loading with vanadium, 9.36% by weight of the mass of support used had to be loaded onto the support as vanadium.

[0212] III.2 Preparation of the Catalysts of the Invention (IE)

[0213] 31.18 g of the Q20C support were weighed into a porcelain dish (base diameter 18 cm) and placed onto an agitator. The latter was set such that the sample was kept in motion. By means of a 3 mL disposable pipette, the vanadium impregnation solution was applied dropwise uniformly to the support and homogenized with a spatula. The mixture then remained on the agitator for 30 minutes and was subsequently dried in an air circulation drying cabinet at 80 C. As soon as the sample was dried, it was cooled back down to room temperature.

[0214] Lastly, the sample was impregnated with the phosphorus impregnation solution (identical procedure) and likewise dried.

[0215] For the further elements, tungsten and optionally tin, it was to be noted that vanadium was preferably always impregnated as the first element and phosphorus as the last. Thus, if further elements were applied in addition to vanadium and phosphorus, vanadium was preferably always impregnated as the first element and then dried. Gradually, all the further elements were applied by this procedure. As the final impregnation, phosphorus was always applied as phosphoric acid solution.

[0216] It is also possible to conduct co-impregnations. For this purpose, impregnation solutions with several components were prepared and impregnated for the corresponding step.

[0217] After the final drying, the samples were calcined. For this purpose, they were heated to 260 C. in a muffle furnace (M110 from Heraeus) in an air stream (1 L/min) with a heating ramp of 1 K/min and kept at 260 C. for two hours, and then cooled down to room temperature. The samples were taken out of the muffle furnace and fine fractions formed (<315 m) were removed by manual sieving.

[0218] Typically, all the components were used as aqueous solutions. Exceptions to this were tin(II) oxalate, which had good solubility only in semiconcentrated nitric acid (1 mol/L), and MoO.sub.3, which was converted in 0.9 molar oxalic acid solution at 80 C. overnight. It was possible to dilute the solution formed to 2 mol/L with DM water.

[0219] Calculation Example

[0220] Support weight, LOI corrected

31.18 g31.18 g*0.0295=30.260 g

[0221] Water uptake of the support (100% ICW)

31.18 g*1.04 mL/g=32.427 mL32.43 mL

[0222] Calculation of the mass of vanadium

m.sub.(V)=(m.sub.(support)m.sub.(support)*LOI)*% by wt. on support.sub.(V)

m.sub.(V)=(31.18 g31.18 g*0.0295)*0.0936=2.832 g

[0223] Calculation of the volume of VO(C.sub.2O.sub.4) solution

m.sub.(V)=M.sub.(V)*c.sub.(V)*V.sub.(V).fwdarw.V.sub.(V)=m.sub.(V)/(M.sub.(V)*c.sub.(V))

V.sub.(V)=2.832 g/(50.94 g/mol*2.2 mol/L)=25.27 mL

[0224] Calculation of the mass of phosphorus

m.sub.(P)=(m.sub.(support)m.sub.(support)*LOI)*% by wt. on support.sub.(P)

m.sub.(P)=(31.18 g31.18 g*0.0295)*0.113=3.419 g

[0225] Calculation of the volume of H.sub.3PO.sub.4 solution

m.sub.(P)=M.sub.(P)*c.sub.(P)* V.sub.(P).fwdarw.V.sub.(P)=m.sub.(P)/(M.sub.(P)*c.sub.(P))

V.sub.(P)=3.419 g/(30.97 g/mol*6 mol/L)=18.40 mL

[0226] Making up the impregnation solutions for 100% ICW [0227] Vanadium impregnation solution

V(H2O content)=31.18 g*1.04 g/mLV.sub.(V)=35.43 mL25.27 mL=10.16 mL [0228] Phosphorus impregnation solution

V(H2O content)=31.18 g*1.04 g/mLV.sub.(P)=35.43 mL18.40 mL=17.03 mL

[0229] 111.3 Catalyst Compositions

[0230] Compositions of catalysts of the invention which have been prepared in III.2 are specified in tables 1 and 2 with percentages by weight and their molar proportions MMR of phosphorus (P), vanadium (V) and tungsten (W) or tin (Sn), and the molar ratio of phosphorus to the sum total of vanadium and tungsten and the molar ratio of vanadium to tungsten or the molar ratio of phosphorus to the sum total of vanadium, tungsten and tin. The molar proportion MMR of a component is defined as shown by way of example below for W:

[00003]$\mathrm{MMR}\left(W\right)=\frac{\frac{\%.Math..Math.\mathrm{by}.Math..Math.\mathrm{wt}..Math.W}{M\left(W\right)}}{\frac{\%.Math..Math.\mathrm{by}.Math..Math.\mathrm{wt}..Math.W}{M\left(W\right)}+\frac{\%.Math..Math.\mathrm{by}.Math..Math.\mathrm{wt}..Math.V}{M\left(V\right)}+\frac{\%.Math..Math.\mathrm{by}.Math..Math.\mathrm{wt}..Math.P}{M\left(P\right)}}$

[0231] where M(W) is the molar mass of tungsten in g/mol, M(V) is the molar mass of vanadium in g/mol and M(P) is the molar mass of phosphorus in g/mol.

TABLE-US-00002 TABLE 1 Overview of catalysts of the invention comprising phosphorus (P), vanadium (V) and tungsten (W) which have been used for catalytic studies Molar ratio of P to the P [% V [% W [% MMR MMR MMR sum total Molar ratio Catalyst by wt.] by wt.] by wt.] (W) (V) (P) of (V and W) of V to W IE1 12.43 6.56 10.14 0.090 0.22 0.69 2.23:1 2.44:1 IE2 11.3 6.56 11.15 0.110 0.23 0.66 1.94:1 2.09:1 IE3 12.43 6.56 11.15 0.100 0.22 0.68 2.13:1 2.20:1 IE4 11.3 7.5 7.44 0.070 0.27 0.66 1.94:1 3.86:1 IE5 11.3 7.5 8.12 0.080 0.26 0.66 1.94:1 3.25:1 IE6 11.3 6.56 10.14 0.1 0.23 0.66 2.00:1 2.30:1 IE7 12.42 7.5 11.61 0.1 0.24 0.66 1.94:1 2.40:1 IE12 15.14 8.43 14.495 0.108 0.23 0.67 2.00:1 2.09:1 IE13 12.42 6.56 11.15 0.1 0.22 0.68 2.13:1 2.20:1 IE14 12.42 6.56 12.27 0.11 0.22 0.67 2.03:1 2.00:1 IE17 11.3 7.5 6.76 0.07 0.27 0.66 1.94:1 3.86:1 IE19 11.3 7.5 8.12 0.08 0.26 0.66 1.94:1 3.25:1 IE20 12.43 6.56 11.15 0.10 0.22 0.68 2.12:1 2.12:1

TABLE-US-00003 TABLE 2 Overview of catalysts of the invention comprising phosphorus (P), vanadium (V), tungsten (W) and tin (Sn) which have been used for catalytic studies Molar ratio of P to the sum total Sn [% P [% V [% W [% MMR MMR MMR MMR of (V, W Catalyst by wt.] by wt.] by wt.] by wt.] (Sn) (W) (V) (P) and Sn) IE8 2.18 12.43 8.43 0 0.03 0 0.28 0.69 2.2 IE18 2.18 11.3 6.56 6.76 0.03 0.07 0.23 0.66 2 IE9 1.09 11.3 8.43 1.69 0.02 0.02 0.3 0.66 1.9 IE10 2.18 11.3 7.5 3.38 0.03 0.03 0.27 0.66 2 IE11 4.37 11.3 6.56 3.38 0.07 0.03 0.23 0.66 2

[0232] Tables 3, 4 and 5 below indicate compositions of comparative catalysts which have been prepared according to III.2.

TABLE-US-00004 TABLE 3 Overview of comparative catalysts which have been used for catalytic studies Bi [% Mo [% P [% V [% W [% MMR MMR MMR MMR MMR Catalyst by wt.] by wt.] by wt.] by wt.] by wt.] (Bi) (Mo) (W) (V) (P) CE1 0 0 11.3 9.36 0 0 0 0 0.33 0.67 CE2 0 0 12.43 9.36 0 0 0 0 0.31 0.69 CE3 0 0 11.3 10.30 0 0 0 0 0.36 0.64 CE4 7.68 0 11.3 7.5 0 0.07 0 0 0.27 0.66 CE5 0 5.3 11.3 6.56 0 0 0.1 0 0.23 0.66 CE6 0 3.5 11.3 7.5 0 0 0.07 0 0.27 0.67 CE8 0 1.76 11.3 9.36 0 0 0.03 0 0.32 0.64 CE10 7 0 12.7 11.4 3.8 0.03 0 0.33 0.05 0.60

TABLE-US-00005 TABLE 4 Overview of comparative catalysts comprising phosphorus (P), vanadium (V) and tungsten (W), where the molar ratio of phosphorus to the sum total of vanadium and tungsten is outside the inventive range, and which were used for catalytic studies Molar ratio of P to the P [% V [% W [% MMR MMR MMR sum total Molar ratio Catalyst by wt.] by wt.] by wt.] (W) (V) #7 (P) of (W and V) of V to W CE11 13.56 7.5 6.76 0.06 0.24 0.70 2.33 4.00 CE12 13.56 6.56 10.14 0.09 0.21 0.70 2.33 2.33 CE13 12.42 8.43 14.495 0.122 0.256 0.621 1.64 2.10 CE14 13.51 8.43 14.495 0.129 0.272 0.599 1.49 2.11 CE15 12.42 8.43 11.15 0.1 0.26 0.64 1.78 2.60 CE16 11.3 7.5 11.61 0.11 0.26 0.63 1.70 2.36

TABLE-US-00006 TABLE 5 Overview of comparative catalysts comprising phosphorus (P), vanadium (V) and tungsten (W), where the molar ratio of vanadium to tungsten is outside the inventive range, and which were used for catalytic studies Molar ratio of P to the P [% V [% W [% MMR MMR MMR sum total Molar ratio Catalyst by wt.] by wt.] by wt.] (W) (V) (P) of (W and V) of V to W CE9 11.3 8.43 3.38 0.03 0.3 0.66 2.00 10.00 CE17 12.43 8.43 3.38 0.03 0.28 0.69 2.23 9.33

[0233] III.4 Catalytic Studies/Use of the Catalysts in the Preparation of Acrylic Acid

[0234] The catalytic studies were conducted on pulverulent samples, for which a spall fraction having a particle size in the range from 0.315 to 0.5 mm was used. For preparation for the studies, the samples were positioned in tubular reactors between two inert particle beds consisting of quartz glass spall, the laden reactors were installed into the catalysis apparatus, a 16-tube high-throughput screening system, and the samples present therein were subjected to the test protocols.

[0235] For this purpose, a stream consisting of formaldehyde, acetic acid, water and argon was heated to 175 C. and hence evaporated. The gaseous mixture was then contacted with an aldol condensation catalyst according to the inventive examples (1E) and comparative examples (CE) in powder form at 1.1 bar [temperature and GHSV as specified in tables 6 to 22; GHSV=total volume flow rate of stream S1, in m.sup.3/h, per unit catalyst volume, in m.sup.3, under standard conditions (0 C. and absolute pressure 1.013 bar) in h.sup.1]. The temperature was measured at the start of the experimentation by means of a thermocouple in the isothermal zone of the reactor, i.e. of the catalyst bed, and corresponded to the temperature at which the reactions were conducted. The product stream was subsequently diluted with nitrogen, and the composition was determined by gas chromatography.

[0236] Tables 6 to 22 show the averaged result, with testing of the samples for 12 h. Catalytic results with inventive catalysts (1E) and comparative catalysts (CE) under different reaction conditions were compared. A negative influence was understood to mean a lowering of the acrylic acid selectivity (S(ACR) [%]), and/or an increase in the selectivity for COx (S(COx)) and/or lowering of the carbon conversion (C). A positive influence was understood to mean an increase in the acrylic acid selectivity (S(ACR) [%]), and/or a lowering of the selectivity for COx (S(COx)) and/or an increase in the carbon conversion (C).

[0237] The carbon conversion (C) was calculated by the following equation:

C=100*(NC.sup.P.sub.sum/(NC.sup.E.sub.FA+NC.sup.E.sub.ACE))

NC.sup.P.sub.sum=(NC.sup.E.sub.FA+NC.sup.E.sub.ACE)(NC.sup.P.sub.FA+NC.sup.P.sub.ACE); [0238] NC.sup.E.sub.FA=number of carbon atoms present in the stream in the form of a formaldehyde source; [0239] NC.sup.E.sub.ACE=number of carbon atoms present in the stream in the form of acetic acid; [0240] NC.sup.P.sub.FA=number of carbon atoms present in the product stream in the form of a formaldehyde source; [0241] NC.sup.E.sub.ACE=number of carbon atoms present in the product stream in the form of acetic acid. [0242] The acrylic acid selectivity (S) was calculated by the following formula:

S=100(NC.sup.P.sub.AS/NC.sup.P.sub.sum).

TABLE-US-00007 TABLE 6 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE7 6.6 84.7 57.2 CE1 8.6 79.8 54.3 CE15 6.8 82.8 45.0 CE1 8.1 81.7 44.4

[0243] Settings: T=350 C., GHSV [h.sup.1]=1000, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.08% by volume

[0244] The inventive catalysts exhibited a positive influence on the selectivity of acrylic acid formation and a positive influence on the formation of CO.sub.x.

TABLE-US-00008 TABLE 7 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE14 5.9 86.8 47.1 IE3 6.9 85.7 53.5 IE13 5.5 86.7 41.5 IE1 4.7 86.8 37.9 CE2 10.9 81.3 53.2 CE3 14.9 77.5 63.6 CE1 15.1 77.6 61.9 CE17 8.6 83.5 51.0 CE15 12.7 80.2 67.0

[0245] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=2.75% by volume

[0246] The inventive catalysts exhibited a positive influence on the selectivity of acrylic acid formation and a positive influence on the formation of CO.sub.x.

TABLE-US-00009 TABLE 8 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE2 4.8 87.3 50.5 IE6 4.7 87.7 49.4 IE20 7.6 84.7 58.2 IE19 6.7 85.7 56.4 IE4 6.6 85.5 56.0 IE17 6.2 86.1 55.7 CE1 8.8 81.7 58.0 CE3 9.4 80.4 56.8 CE1 9.5 80.9 57.4 CE5 10.8 81.1 54.1 CE16 8.1 83.7 60.0 CE15 7.8 83.9 60.2

[0247] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.38% by volume

[0248] The inventive catalysts exhibited a positive influence on the selectivity of acrylic acid formation and a positive influence on the formation of CO.sub.x. The comparative catalysts which comprised bismuth exhibited a negative influence on the selectivity of acrylic acid formation and the carbon conversion (C).

TABLE-US-00010 TABLE 9 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) which comprised bismuth (Bi) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE3 6.9 85.7 53.5 CE4 7.0 63.0 10.0

[0249] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=2.75% by volume

[0250] The comparative catalyst which comprised bismuth exhibited a negative influence on the selectivity of acrylic acid formation and the carbon conversion.

TABLE-US-00011 TABLE 10 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) which comprised molybdenum (Mo) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE8 6.8 85.2 51.5 CE6 10.1 82.0 55.5 CE5 10.8 81.1 54.1 CE8 10.0 81.0 55.2

[0251] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.38% by volume

[0252] The comparison showed the negative influence of molybdenum on the selectivity of acrylic acid formation and the negative influence on the formation of CO.sub.x.

TABLE-US-00012 TABLE 11 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) which comprised tungsten (W) and tin (Sn) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE18 4.4 87.6 45.4 IE10 6.0 86.1 53.1 IE11 4.3 87.3 42.3 IE9 7.3 84.5 56.6 CE1 9.5 80.9 57.4

[0253] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.38% by volume

[0254] The comparison showed the positive influence of tin- and tungsten-containing inventive catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00013 TABLE 12 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE19 11.4 82.6 52.7 IE7 12.3 81.2 57.4 CE1 14.6 78.6 60.0

[0255] Settings: T=340 C., GHSV [h.sup.1]=1000, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.944% by volume

[0256] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00014 TABLE 13 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE19 10.6 83.8 39.6 IE5 10.1 84.8 44.6 CE1 13.0 81.1 45.9

[0257] Settings: T=340 C., GHSV [h.sup.1]=3500, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.944% by volume

[0258] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00015 TABLE 14 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE19 8.4 85.7 53.2 IE5 8.4 85.9 60.4 CE1 11.0 82.3 62.1

[0259] Settings: T=350 C., GHSV [h.sup.1]=1000, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.944% by volume

[0260] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00016 TABLE 15 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE19 10.1 82.8 46.8 IE5 9.3 83.9 50.3 IE7 5.3 90.7 54.9 CE1 12.9 79.6 51.8

[0261] Settings: T=350 C., GHSV [h.sup.1]=3500, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.944% by volume

[0262] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00017 TABLE 16 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE19 12.8 81.5 58.8 IE5 11.9 88.2 77.4 CE1 14.4 76.5 68.6

[0263] Settings: T=350 C., GHSV [h.sup.1]=800, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.944% by volume

[0264] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00018 TABLE 17 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE19 8.5 84.2 52.7 IE5 8.8 84.1 57.2 CE1 11.8 80.2 59.5

[0265] Settings: T=360 C., GHSV [h.sup.1]=3500, acetic acid content=9% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=1.944% by volume

[0266] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00019 TABLE 18 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE2 7.0 85.2 54.8 IE6 5.5 86.6 47.8 IE19 7.7 84.8 54.7 IE4 8.7 83.3 55.9 IE17 7.4 84.5 52.4 CE1 11.6 80.0 56.3 CE5 14.3 77.7 52.2 CE16 9.8 82.0 62.9 CE15 9.9 81.9 62.1

[0267] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=13.5% by volume, formaldehyde content=13.5% by volume, H.sub.2O content=22.8% by volume, oxygen content=2.75% by volume

[0268] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00020 TABLE 19 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Catalyst S(COx) [%] S(ACR) [%] Carbon conversion (C) [%] IE2 9.0 83.6 55.3 IE6 7.2 85.6 49.3 IE4 10.8 81.7 55.5 IE17 9.7 83.2 53.2 CE1 15.2 76.7 62.7 CE1 15.9 76.8 57.9 CE3 16.2 75.2 58.3 CE1 14.4 78.0 56.5 CE15 13.4 79.7 62.3 CE16 13.1 80.0 63.5

[0269] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=9% by volume, formaldehyde content=13.5% by volume, H.sub.2O content=22.8% by volume, oxygen content=2.75% by volume

[0270] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00021 TABLE 20 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Carbon conversion (C) Catalyst S(COx) [%] S(ACR) [%] [%] IE4 9.5 81.6 56.0 IE2 9.6 81.5 55.8 IE6 8.1 83.1 53.3 IE17 10.0 81.1 55.6 CE9 11.6 79.5 54.3 CE16 12.2 78.3 57.4 CE15 12.2 78.4 57.1 CE1 13.1 76.2 55.5 CE3 13.6 75.1 55.0

[0271] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=13.5% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=2.75% by volume

[0272] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00022 TABLE 21 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Carbon conversion (C) S(COx) [%] S(ACR) [%] [%] IE12 7.5 85.3 54.4 CE13 13.0 80.0 68.2 CE14 10.2 82.8 62.7

[0273] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=13.5% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=2.75% by volume

[0274] The comparison showed the positive influence of vanadium- and tungsten-containing catalysts on the selectivity of acrylic acid formation and the positive influence on the formation of CO.sub.x.

TABLE-US-00023 TABLE 22 Overview of acrylic acid selectivity (S(ACR)), selectivity for COx (S(COx)) and carbon conversion (C) for inventive catalysts (IE) compared to comparative catalysts (CE) Carbon conversion (C) S(COx) [%] S(ACR) [%] [%] CE11 5 85.6 32.9 CE12 4 86 30.5 IE20 6.8 85.7 53.5

[0275] Settings: T=370 C., GHSV [h.sup.1]=1256, acetic acid content=13.5% by volume, formaldehyde content=9% by volume, H.sub.2O content=15.2% by volume, oxygen content=2.75% by volume

[0276] The comparison showed the positive influence of the inventive molar ratio of P to the sum total of (W and V) on the carbon conversion (C).