Process for vapor-phase methanol carbonylation to methyl formate, a catalyst used in the process and a method for preparing the catalyst

Abstract

A process for vapor-phase carbonylation of methanol to methyl formate, whereby a feed gas containing methanol, carbon monoxide, hydrogen and oxygen is passed through a reactor loaded with a supported nano-scaled platinum group metal heterogeneous catalyst to produce methyl formate by a vapor-phase carbonylation reaction, under reaction conditions with a space velocity of 500-5000 h.sup.1, a temperature of 50-150 C. and a pressure of 0.01-2 MPa. Supported nano-scaled platinum group metal heterogeneous catalysts are prepared via ultrasonic dispersion and calcination. Methyl formate is produced and isolated under relatively mild conditions.

Claims

1. A process for vapor-phase carbonylation of methanol to methyl formate, in which a feed gas containing methanol, carbon monoxide, hydrogen and oxygen is passed through a reactor loaded with a supported nano-scaled platinum group metal heterogeneous catalyst to produce methyl formate by a vapor-phase carbonylation reaction, under reaction conditions with a gas hourly space velocity of 500-5000 h1, a temperature of 50-150 C. and a pressure of 0.01-2 MPa, wherein the supported nano-scaled platinum group metal heterogeneous catalyst comprises a nano-scaled platinum group metal active component and a carrier, wherein, the percentage content of the nano-scaled platinum group metal active component is 0.01-2% by mass of the carrier; said nano-scaled platinum group metal active component is one metal or a mixture of two or more metals selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum, or an alloy of two or more metals selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum; said carrier is one or more selected from alumina, silica, magnesia, zinc oxide, zirconia, titania, metal-organic framework compounds, activated carbon, molecular sieves, carbon nanotubes, and graphene; and wherein said feed gas comprises 10-50% by volume of methanol, 10-50% by volume of carbon monoxide, 10-30% by volume of hydrogen, and 5-20% by volume of oxygen.

2. The process according to claim 1, in which said reactor is a fixed bed reactor or multiple fixed bed reactors connected in series and/or in parallel manner.

3. The process according to claim 1, wherein the particle size of said nano-scaled platinum group metal active component is 0.5-10 nm.

4. The process according to claim 1, wherein the supported nano-scaled platinum group metal heterogeneous catalyst further comprises a promoter, wherein, the percentage content of metal elements in the promoter is 20% or less by mass of the carrier; and said promoter is one metal or a mixture of two or more metals selected from iron, cobalt, nickel and copper; or one or more oxides selected from iron oxides, cobalt oxides, nickel oxide and copper oxides.

5. The process according to claim 1, wherein the supported nano-scaled platinum group metal heterogeneous catalyst is prepared by a method comprising the steps as follows: a) placing a carrier into a solution containing a platinum group metal salt and a solvent, mixing uniformly, and ultrasonically dispersing the solution containing the platinum group metal salt onto the carrier; b) drying the sample obtained from step a) at 100-200 C. for 1-20 hours, and calcining at 200-600 C. for 1-20 hours; c) adding the sample obtained from step b) into a solution comprising a reductant, a capping agent, and a stabilizer, and carrying out a reduction reaction at 20-120 C.; and d) washing and drying the sample obtained from step c) in vacuum to obtain said supported nano-scaled platinum group metal heterogeneous catalyst.

6. The process according to claim 5, wherein the catalyst further comprises a promotor, wherein, the percentage content of metal elements in the promoter is 20% or less by mass of the carrier; and said promoter is one metal or a mixture of two or more metals selected from iron, cobalt, nickel and copper; or one or more oxides selected from iron oxides, cobalt oxides, nickel oxide and copper oxides; and the carrier is treated as follows before used in step a): placing a carrier into a solution containing a promoter metal salt, standing for 1-20 hours, drying and calcining; and said promoter metal salt being one or more selected from nitrates, acetates, and halides of iron, cobalt, nickel and copper.

7. The process according to claim 5, wherein said platinum group metal salt is one or more selected from acetates, nitrates, halides and acetyl acetonates of a platinum group metal.

8. The process according to claim 5, wherein said reductant is one or more selected from sodium borohydride, hydrazine hydrate, ascorbic acid, formaldehyde, formic acid, sodium formate, sodium acetate, glucose, and ethylene glycol; said capping agent is one or more selected from sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, citric acid, sodium citrate, potassium citrate, and ammonium citrate; and said stabilizer is one or more selected from polyvinylpyrrolidone, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer.

9. The process according to claim 6, wherein said platinum group metal salt is one or more selected from acetates, nitrates, halides and acetyl acetonates of a platinum group metal.

10. The process according to claim 6, wherein said reductant is one or more selected from sodium borohydride, hydrazine hydrate, ascorbic acid, formaldehyde, formic acid, sodium formate, sodium acetate, glucose, and ethylene glycol; said capping agent is one or more selected from sodium chloride, potassium chloride, sodium bromide, potassium bromide, sodium iodide, potassium iodide, citric acid, sodium citrate, potassium citrate, and ammonium citrate; and said stabilizer is one or more selected from polyvinylpyrrolidone, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride, and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer.

Description

DESCRIPTION OF ACCOMPANYING FIGURES

(1) FIG. 1 is a transmission electron micrograph image of catalyst 5 in 20 nm-scale.

(2) FIG. 2 is a transmission electron micrograph image of catalyst 5 in 10 nm-scale.

SPECIFIC EMBODIMENTS FOR CARRYING OUT THE INVENTION

(3) The invention is described in detail by the following examples, but the present invention is not limited to these examples.

(4) The raw materials and reagents used in the examples were purchased commercially, applied directly without any special treatment.

Example 1: Preparation of Catalyst 1

(5) 1 g of alumina was weighed, impregnated into 15 mL ethanol solution of 50 mmol/L CuCl.sub.2.2H.sub.2O, stood for 18 hours, dried at 100 C. for 15 hours, calcined at 400 C. for 5 hours, then impregnated again into 1.25 mL aqueous solution of 37.6 mmol/L potassium chloropalladite, and 4 mL water was added, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, added with 0.1 g of ascorbic acid, 0.2 g of citric acid and 0.5 g of polyvinylpyrrolidone, reduced at 90 C. for 1 hour, dried in vacuum at 60 C. for 15 hours, to obtain PdCu/Al.sub.2O.sub.3 catalyst 1 for use in the reaction of vapor-phase methanol carbonylation to methyl formate.

Example 2: Preparation of Catalyst 2

(6) 1 g of alumina was weighed, impregnated into 15 mL ethanol solution of 50 mmol/L CuCl.sub.2.2H.sub.2O, stood for 18 hours, dried at 100 C. for 15 hours, calcined at 400 C. for 5 hours, then impregnated again into 0.68 mL aqueous solution of 37.6 mmol/L chloroplatinic acid, and 4 mL water was added, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, added with 0.1 g of ascorbic acid, 0.2 g of citric acid and 0.5 g of polyvinylpyrrolidone, reduced at 90 C. for 1 hour, dried in vacuum at 60 C. for 15 hours, to obtain PdCu/Al.sub.2O.sub.3 catalyst 2 for use in the reaction of vapor-phase methanol carbonylation to methyl formate.

Example 3: Preparation of Catalyst 3

(7) 1 g of magnesia was weighed, impregnated into 17 mL ethanol solution of 50 mmol/L Ni(NO.sub.3).sub.2.6H.sub.2O, stood for 18 hours, dried at 100 C. for 15 hours, calcined at 400 C. for 5 hours, then impregnated again into 0.63 mL aqueous solution of 37.6 mmol/L potassium chloropalladite, and 4 mL water was added, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, added with 0.1 mL formaldehyde, 0.24 g of sodium citrate and 0.6 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, reduced at 100 C. for 2 hours, dried in vacuum at 60 C. for 15 hours, to obtain PtPdNi/MgO catalyst 3 for use in the reaction of vapor-phase methanol carbonylation to methyl formate.

Example 4: Preparation of Catalyst 4

(8) 1 g of magnesia was weighed, impregnated into 17 mL ethanol solution of 50 mmol/L Ni(NO.sub.3).sub.2.6H.sub.2O, stood for 18 hours, dried at 100 C. for 15 hours, calcined at 400 C. for 5 hours, then impregnated again into a mixing aqueous solution of 0.65 mL 37.6 mmol/L rhodium chloride hydrate and 0.34 mL 37.6 mmol/L chloroplatinic acid, and 4 mL water was added, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, added with 1 mL formaldehyde, 0.24 g of sodium citrate and 0.6 g of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, reduced at 100 C. for 2 hours, dried in vacuum at 60 C. for 15 hours, to obtain PtRhNi/MgO catalyst 4 for use in the reaction of vapor-phase methanol carbonylation to methyl formate.

Example 5: Preparation of Catalyst 5

(9) 1 g of alumina was weighed, impregnated into 1.25 mL aqueous solution of 37.6 mmol/L potassium chloropalladite, and 4 mL water was added, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, added with 0.1 g of ascorbic acid, 0.2 g of citric acid and 0.5 g of polyvinylpyrrolidone, reduced at 90 C. for 1 hour, dried in vacuum at 60 C. for 15 hours, to obtain Pd/Al.sub.2O.sub.3 catalyst 5 for use in the reaction of vapor-phase methanol carbonylation to methyl formate.

Example 6: Preparation of Catalysts 6 to 11

(10) 1 g of carrier was weighed, impregnated into 2 mL solution containing platinum group metal salts, then added with 4 mL water, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, and added with an amount of a reductant, a capping agent and a stabilizer, reduced at 90 C. for 1 hour, dried in vacuum at 60 C. for 15 hours, to obtain catalyst 6 to catalyst 11. The numbers and specific preparation conditions of the catalysts are shown in Table 1.

(11) TABLE-US-00001 TABLE 1 Conditions for preparation of catalyst 6~catalyst 11 Solutions of platinum group metal salts Mass of platinum Numbers Solutes and group Types and added amounts of of solvent in elements in reductant, capping agent and samples Carriers solutions solutions stabilizer Catalyst 6 zirconia Aqueous solution Ruthenium: Sodium borohydride 0.01 g, sodium of ruthenium 0.0001 g chloride 0.1 g, cetyl trimethyl nitrate ammonium bromide 0.3 g Catalyst 7 titanium Hydrochloric acid Iridium: 0.001 g Hydrazine hydrate 0.01 g, KCl 0.1 g, dioxide solution of cetyl trimethyl ammonium iridium trichloride chloride 0.3 g Catalyst 8 silicon Aqueous solution Osmium: 0.01 g formic acid 2 mL, sodium bromide dioxide of osmium 0.4 g, polyvinyl pyrrolidone 1 g trichloride Catalyst 9 zinc oxide Hydrochloric acid Iridium: 0.01 g (Sodium formate 0.1 g + sodium solution of Osmium: acetate 0.1 g), potassium bromide iridium trichloride 0.005 g 0.4 g, cetyl trimethyl ammonium and osmium bromide 1 g trichloride Catalyst Activated Ethanol solution Palladium: Glucose 2 g, sodium iodide, 0.5 g, 10 carbon of palladium 0.012 g Polyvinylpyrrolidone 2 g chloride Catalyst 0.5 g Aqueous solution Rhodium: 0.02 g Ethylene glycol 4 g, potassium 11 alumina + 0.5 g of sodium iodide 1 g, cetyl trimethyl zinc oxide hexachlororhodate ammonium chloride 3 g

Example 7: Preparations of Catalysts 12-17

(12) 1 g of carrier was weighed, placed into 17 mL solution containing promoter metal salts, stood for 18 hours, dried at 100 C. for 15 hours, calcined at 400 C. for 5 hours, then again impregnated into 2 mL solution containing platinum metal salts, again added with 4 mL water, stirred for 3 hours, dispersed ultrasonically for 3 hours, dried at 120 C. for 15 hours, calcined at 400 C. for 5 hours, and added with an amount of a reductant, a capping agent and a stabilizer, reduced at 100 C. for 1 hour, dried in vacuum at 60 C. for 15 hours, to obtain catalyst 12 to catalyst 17. The numbers and specific preparation conditions of the catalysts are shown in Table 2.

(13) TABLE-US-00002 TABLE 2 Conditions for preparation of catalyst 12~catalyst 17 Solution containing platinum Solution containing group metal salts promoter metal salts Mass of Mass of platinum Types and added Solutes and promoter Solutes and group metal amounts of reductant, solvents in metal solvents in elements in capping agent and Number Carriers solutions elements solutions solutions stabilizer Catalyst Zirconia Aqueous Iron: 0.005 g Aqueous solution Ruthenium: Sodium borohydride 12 solution of of ruthenium 0.0001 g 0.01 g, sodium ferric nitrate chloride 0.1 g, cetyl chloride trimethyl ammonium bromide 0.3 g Catalyst Titanium Aqueous Cobalt: Hydrochloric acid Iridium: Hydrazine hydrate 13 dioxide solution of 0.01 g solution of 0.001 g 0.01 g, KCl 0.1 g, cobalt iridium trichloride cetyl trimethyl chloride ammonium chloride 0.3 g Catalyst Silica Ethanol Cooper: Aqueous solution Osmium: Formic Acid 2 mL, 14 solution of 0.04 g of osmium 0.01 g sodium bromide 0.4 g, copper Nickel: trichloride polyvinyl nitrate and 0.04 g pyrrolidone 1 g nickel chloride Catalyst Zinc Ethanol Nickel: 0.1 g Hydrochloric acid Iridium: (Sodium formate 0.1 g + 15 oxide solution of solution of 0.01 g sodium acetate, nickel iridium trichloride Osmium: 0.1 g), potassium nitrate and osmium 0.005 g bromide 0.4 g, cetyl trichloride trimethyl ammonium bromide 1 g Catalyst Activated Aqueous Copper: Ethanol solution Palladium: Glucose 2 g, sodium 16 Carbon solution of 0.05 g of palladium 0.012 g iodide 0.5 g, copper Cobalt: chloride Polyvinylpyrrolidone chloride, 0.05 g 2 g cobalt Iron: 0.05 g chloride and iron chloride Catalyst 0.5 g Aqueous Cobalt: 0.2 g Aqueous solution Rhodium: Ethylene glycol 4 g, 17 alumina + solution of of sodium 0.02 g potassium iodide 1 g, 0.5 g cobalt hexachlororhodate cetyl trimethyl zinc oxide chloride ammonium chloride 3 g

Example 8: Transmission Electron Micrograph (TEM) Characterization of Catalysts

(14) Catalysts 1 to 17 were characterized by TEM using Tecnai F20, FEI. The resulting TEM images showed that the platinum group metal as active center was uniformly distributed on the carrier, with particle size distribution in the range between 0.5-10 nm, more focused distribution in the range of 1-8 nm, further focused in the range of 1-5 nm. Wherein, a typical TEM image is represented by catalyst 5, as shown in FIG. 1 and FIG. 2. As seen from FIG. 1, as the active center, the particles of palladium are relatively uniform, with the range of particle size focused in 1-5 nm; as seen from FIG. 2, the range of particle size distribution of the palladium active component is also between 1-5 nm.

Example 9: Performance Evaluation of Catalysts 1-5

(15) Catalysts 1-5 were loaded into a fixed bed reactor used in the reaction of vapor-phase methanol carbonylation to methyl formate, with a ratio of CH.sub.3OH:CO:H.sub.2:O.sub.2 in feed gas being 18:18:9:5 (volume ratio), a space velocity of 2000 h.sup.1, a reaction temperature of 100 C., and a reaction pressure of 0.1 MPa. The purity of CH.sub.3OH is chemical purity, and the purity of CO, H.sub.2 and O.sub.2 is 99.9%, the reaction results are shown in Table 3.

(16) TABLE-US-00003 TABLE 3 Catalytic performances of catalysts 1~5 in the reaction of vapor-phase methanol carbonylation to methyl formate Selectivity for Space-time yield of Conversion of methyl formate methyl formate Catalyst CO (%) (%) (g .Math. L.sup.1 .Math. h.sup.1) Catalyst 1 75 92 1376 Catalyst 2 82 94 1537 Catalyst 3 87 99 1718 Catalyst 4 93 99 1836 Catalyst 5 70 95 1326

Example 10: Performance Evaluation of Catalysts 6-17

(17) The resulting catalysts 6-17 were loaded into a fixed bed reactor used in the reaction of vapor-phase methanol carbonylation to methyl formate. The reaction conditions and the reaction results are shown in Table 4.

(18) TABLE-US-00004 TABLE 4 Reaction conditions and catalytic performances of Catalyst 6~Catalyst 17 in the reaction of vapor-phase methanol carbonylation to methyl formate Reaction conditions Percentage content of Results of reactions methanol, carbon Selectivity Space-time monoxide, hydrogen and Space for methyl yield of methyl oxygen in feed gas, by velocity Temperature Presure Conversion formate formate Catalysts volume (h.sup.1) ( C.) (MPa) of CO (%) (%) (g .Math. L.sup.1 .Math. h.sup.1) Catalyst 6 20%, 50%, 20%, 10% 500 50 0.01 5 80 27 Catalyst 7 30%, 40%, 15%, 15% 1000 80 0.08 12 82 105 Catalyst 8 40%, 40%, 10%, 10% 2000 100 0.1 18 70 270 Catalyst 9 50%, 30%, 10%, 10% 3000 150 1 27 75 488 Catalyst 10 50%, 20%, 25%, 5% 4000 50 1.5 60 95 1221 Catalyst 11 40%, 10%, 30%, 20% 5000 80 2 75 90 904 Catalyst 12 20%, 50%, 20%, 10% 2200 100 0.01 8 81 191 Catalyst 13 30%, 40%, 15%, 15% 2300 150 0.08 17 84 352 Catalyst 14 40%, 40%, 10%, 10% 3000 50 0.1 24 73 563 Catalyst 15 50%, 30%, 10%, 10% 3500 80 1 33 78 724 Catalyst 16 50%, 20%, 25%, 5% 4000 100 1.5 67 97 1393 Catalyst 17 40%, 10%, 30%, 20% 5000 150 2 81 92 998

(19) The above description is only several examples of the invention, without limiting the invention in any way. Although the invention is disclosed by the preferred examples as above, they are not used for limiting the invention. Various alternations or modifications made by a person skilled in the art utilizing the above disclosed technical contents without departing the scope of the technical solution of the invention are all equivalent embodiments, which belong to the scope of the technical solution of the invention.