The CO carbonylation producing oxalic ester of a kind of dipping-controlled reducing process preparation is with efficient nano Pd catalyst
Technical field
The present invention relates to a kind of efficient nano Pd catalyst, relate in particular in the two-step method coal-ethylene glycol CO gas phase carbonylation producing oxalic ester with efficient nano Pd catalyst.
Technical background
Ethylene glycol is a kind of extremely important, strategic large chemical industry base stock, at present, more than 2,000 ten thousand tons of world's annual requirements, wherein 1/3rd the market demand is in China.The total output of whole world ethylene glycol surpasses 1,800 ten thousand tons, and about 1,500,000 tons of the production capacity of China, about 5,000,000 tons of breach, imbalance between supply and demand is very outstanding, a large amount of dependence on import.At present mainly by oil ethene route synthesizing glycol, and China is the country of the few oil of a rich coal, thereby the development coal-ethylene glycol not only can be alleviated the imbalance between supply and demand of ethylene glycol effectively, and can promote the level of coal resources high-efficiency cleaning trans-utilization.Oxalate is significant for the strategic objective that realizes coal-ethylene glycol as wherein important coal-ethylene glycol intermediate product.In addition, oxalate also is a kind of important Organic Chemicals, can be used for preparing the intermediate of oxalic acid, oxalyl chloride, oxamides, ethylene glycol, some drugs, dyestuff and solvent.
At present, domestic oxalic acid and the alcohol of still adopting is that dehydrating agent esterification dehydration method is produced oxalate with toluene or benzene.This method production technology cost is high, energy consumption is big, seriously polluted, prepared using is unreasonable.The sixties in 20th century, U.S. Fenton reported that the direct coupling of a kind of CO and alcohol becomes the method for oxalate, the new way of having opened up C1 chemical synthesis oxalate.But this reaction needed is carried out under pressurized conditions, and Ube Industries Ltd. has announced a kind of employing platinum group metal loaded catalyst subsequently, utilizes the technological process of CO and methyl nitrite normal pressure synthesizing dimethyl oxalate.This technology has good, the advantages such as reaction condition is gentle, less energy consumption, three-waste free discharge, good product quality of Atom economy, generally payes attention to and receive both at home and abroad.The catalyst space-time yield of the emerging product report of space portion is 432 g L
-1h
-1, through 480 hours successive reactions, yield did not reduce.But its noble metal use amount is big, the catalyst cost is higher, and space-time yield is lower.There are a lot of patents to report for work subsequently and in catalyst, add Zr (CN95116136.9), Ce (CN02111624.5), Ti (CN200710061392.2), La (CN200810114383.X), Ir (CN200810035248.6), Ni (CN200910307543.7), MO
x(CN200910061854.X) etc. auxiliary agent improves the space-time yield of oxalate.At present, the highest 1000g L that reached of catalyst space-time yield
-1h
-1More than, but air speed is all very high, and the consumption of major catalyst Pd is still than higher, reaction temperature is also than higher in addition.The catalyst of at present having reported that is used for CO gas phase carbonylation producing oxalic ester all adopts traditional immersion process for preparing, and all adopts high-temperature hydrogen or carbon monoxide reduction activation at last.The tradition infusion process is because the influence of group's cluster effect of solvation effect that receives immersion solvent and active component is difficult for making active group high degree of dispersion, and active component may the crystallite coalescence in follow-up roasting and high temperature reduction process, causes the catalytic activity reduction.Therefore, developing a kind of new method prepares CO gas phase carbonylation producing oxalic ester and has with high activity low noble metal load capacity nanocatalyst that great economy is worth and social effect.
Summary of the invention
The object of the present invention is to provide a kind of employing dipping-ultrasonic-controlled reducing process of alkali-free liquid phase to prepare efficient nano Pd catalyst.Compare with existing catalyst, this catalyst can be under lower temperature and low noble metal load capacity efficiently catalysis CO gas phase carbonylation become oxalate, CO conversion ratio, oxalate selectivity and space-time yield are all than higher.
Another object of the present invention is to provide the application of efficient nano Pd catalyst in the reaction of CO gas phase carbonylation producing oxalic ester, wherein oxalate can be any in dimethyl oxalate or the diethy-aceto oxalate.
Another purpose of the present invention is to provide the dipping-ultrasonic-controlled reducing preparation method of alkali-free liquid phase of efficient nano Pd catalyst.
The objective of the invention is to realize by following technical scheme; Efficient nano Pd catalyst of the present invention is characterized in that: the catalyst activity component is the Pd nano particle, and catalyst carrier is an Alpha-alumina; In the quality of carrier, wherein the weight percent content of Pd is 0.05 – 2%.
Catalyst carrier provided by the invention is an Alpha-alumina, and its surface area is 1 – 10m
2/ g handles 2 – through 800 ℃ of 400 – in advance and obtained in 10 hours.
Efficient nano Pd Preparation of catalysts method of the present invention comprises the steps:
(1) the carrier Alpha-alumina is impregnated in the Pd precursor solution, stirs:
During actual fabrication: the Pd precursor wiring solution-forming that takes by weighing certain mass; Make its concentration remain on 0.001 – 0.1mol/L; The carrier Alpha-alumina is placed Pd precursor solution, and stirring at room 1 – 20 hours is distributed in the Pd precursor solution Alpha-alumina equably;
(2) ultrasonic dispersion under heating condition:
Mixed liquor ultrasonic solvent evaporates to solution under heating condition of Pd precursor in the step (1) and Alpha-alumina is done, made the Pd precursor be adsorbed onto the Alpha-alumina surface equably;
(3) dry, roasting:
Sample 100 – in baking oven that step (2) is obtained adsorbing descended dry 1-20 hour for 200 ℃, and 600 ℃ of roastings of 200 –, 1 – is 20 hours then;
(4) the controlled reduction of alkali-free liquid phase:
The sample that step (3) is obtained adds reducing agent, structure directing reagent and protective agent and carries out the controlled reduction of liquid phase under the condition of no alkaline additive; Prepare and be of a size of 2 – 10nm, pattern is that sphere, cube or polyhedron and exposed crystal face are the nanometer Pd catalyst of (111), (100) or (110);
(5) vacuum drying:
The sample that step (4) is obtained through filter, washing, put into dry 1 – of vacuum drying chamber 20 hours, just obtain efficient nano Pd catalyst of the present invention.
The Pd precursor is following any or two or more any proportioning combination in said preparation method's the step (1): palladium nitrate, palladium, palladium bichloride, potassium chloropalladite, potassium chloropalladate, ammonium chloropalladate, palladium acetylacetonate, dichloro diamino palladium, dichloro four ammonia palladiums.
The solvent that is used to dissolve the Pd precursor in said preparation method's the step (1) is to be selected from the following combination in any that can dissolve any or following two or more solvents of Pd precursor solvent: water, methyl alcohol, ethanol, propyl alcohol, butanols, acetone, chloroform, toluene, acetonitrile, benzene, cyclohexane, pyridine, ethylene glycol, ethyl acetate, ether.
Heating-up temperature is 100 ℃ of 20 – in said preparation method's the step (2), 60 ℃ of preferred 30 –; The ultrasonic energy dispersive of every gram catalyst is 10 – 500W, preferred 150 – 350W.
The reducing agent of the controlled reduction of alkali-free liquid phase adopts at least a in strong reductant, middle strong reductant or the weak reductant in said preparation method's the step (4); Described strong reductant is selected from sodium borohydride or hydrazine hydrate; Strong reductant is selected from least a in ascorbic acid, formic acid, sodium formate, the sodium acetate in described, and described weak reductant is selected from least a in citric acid, glucose, the ethylene glycol; Described structure directing reagent has a kind of sodium chloride, potassium chloride, sodium bromide, KBr, sodium iodide, KI, citric acid, natrium citricum, potassium citrate, ammonium citrate of being selected from least; Described protective agent has a kind of polyvinylpyrrolidone (PVP), softex kw (CTAB), hexadecyltrimethylammonium chloride (CTAC), polyethylene oxygen-polypropylene oxygen-polyethylene oxygen (P123) of being selected from least; The above-mentioned reducing agent and the mol ratio of metallic precursor are (2 – 5): 1; The mol ratio of structure directing reagent and protective agent and metallic precursor is (5 – 20): 1, and the ratio between structure directing reagent and the protective agent can be 1: (1 – 5) is preferably 1:2; Reduction temperature is 150 ℃ of 40 –, and 120 ℃ of preferred 80 – compare with the conventional high-temperature hydrogen reducing, have greatly reduced reduction temperature, have avoided the sintering and the reunion of metallic particles.
Efficient nano Pd catalyst applications of the present invention is in the reaction of CO gas phase carbonylation producing oxalic ester, and wherein oxalate is any in dimethyl oxalate or the diethy-aceto oxalate.
CO gas phase carbonylation producing oxalic ester provided by the invention comprises the steps: with efficient nano Pd Application of Catalyst method
Be reflected in the miniature evaluating catalyst of the normal pressure system and carry out, adopt fixed bed reactors, catalyst amount is 0.2 – 2mL, N in the unstripped gas
2: CO:RONO=(30 – 70): (20 – 40): (10 – 30) (volume ratio), gas phase air speed are 2000 – 5000h
-1, preferred 2500 – 4000h
-1, reaction temperature is 160 ℃ of 90 –, reaction pressure is 0.01 – 0.2Mpa, analyzes raw material and product through the gas-chromatography on-line monitoring.
The present invention compared with prior art has following characteristics:
1. catalyst adopts the controlled reducing process preparation of dipping-ultrasonic-alkali-free liquid phase, and active component Pd high degree of dispersion is at carrier surface.
2. the weight percent content of active component Pd in catalyst is 0.05 – 2%, generally is merely 0.5% of carrier quality, can reduce the noble metal use amount greatly.
3. can be under lower temperature and low noble metal load capacity efficiently catalysis CO gas phase carbonylation become oxalate, the CO conversion per pass reaches 48%, the oxalate selectivity is greater than 99%, the oxalate space-time yield is greater than 1000g L
-1h
-1(air speed is 3000h-
-1).
4. catalyst preparation process is simple, cost is low, helps realizing industrialization.
Description of drawings
Fig. 1 is 0.5% Pd/ α-Al of embodiment 1 preparation
2O
3The transmission electron microscope photo of nanocatalyst.
Fig. 2 is 0.5% Pd/ α-Al of embodiment 2 preparations
2O
3The transmission electron microscope photo of nanocatalyst.
Fig. 3 is 0.5% Pd/ α-Al of embodiment 3 preparations
2O
3The transmission electron microscope photo of nanocatalyst.
Fig. 4 is 0.5% Pd/ α-Al of embodiment 4 preparations
2O
3The transmission electron microscope photo of nanocatalyst.
Fig. 5 is 0.5% Pd/ α-Al of embodiment 1 preparation
2O
3The chromatography figure of nanocatalyst.
Fig. 6 is 0.5% Pd/ α-Al of embodiment 2 preparations
2O
3The chromatography figure of nanocatalyst.
Fig. 7 is 0.5% Pd/ α-Al of embodiment 3 preparations
2O
3The chromatography figure of nanocatalyst.
Fig. 8 is 0.5% Pd/ α-Al of embodiment 4 preparations
2O
3The chromatography figure of nanocatalyst.
The specific embodiment
Below in conjunction with specific embodiment the present invention is described further, but the present invention is not limited to following examples.
Embodiment 1:
Take by weighing the 1g Alpha-alumina and be impregnated into the K of 1.25mL 37.6mmol/L
2PdCl
4-In the aqueous solution, add 4mL ethanol again, stirred 3 hours, in 40 ℃ of water-baths with the ultrasonic dispersion of the energy of 200W 4 hours; 110 ℃ of dryings 4 hours, 400 ℃ of roastings 4 hours add the 0.070g ascorbic acid, 0.353g KBr; 0.444g PVP, 100 ℃ were reduced 60 ℃ of dryings of vacuum 10 hours 30 minutes.Transmission electron microscope photo is seen Fig. 1, can know that by figure Pd is dispersed in carrier surface, and particle is mainly sphere, and a small amount of irregular polyhedrons is arranged, and average-size is 6 – 7nm.
Evaluating catalyst: in the reaction of CO gas phase carbonylation producing oxalic ester, catalyst amount is 1mL, N in the unstripped gas with the catalyst applications in the embodiment of the invention
2: CO:RONO=48:28:20 (volume ratio), the gas phase air speed is 3000h
-1, reaction temperature is 130 ℃, reaction pressure is 0.1Mpa, analyzes raw material and product through the GC on-line monitoring.Fig. 5 is seen in chromatography, and reaction result is seen table 1.
Embodiment 2:
Take by weighing the 1g Alpha-alumina and be impregnated into the Pd (NO of 1.25mL 37.6mmol/L
3)
2-In the aqueous solution, add 4mL acetone again, stirred 3 hours; In 35 ℃ of water-baths with the ultrasonic dispersion of the energy of 200W 3 hours, 110 ℃ of dryings 4 hours, 400 ℃ of roastings 4 hours; Add the 0.105g citric acid, 0.353g KBr, 0.444g PVP; 90 ℃ were reduced 15 hours, and then added 90 ℃ of reduction of 0.018g ascorbic acid continuation 30 minutes, 60 ℃ of dryings of vacuum 10 hours.Transmission electron microscope photo is seen Fig. 2, can know that by figure Pd is dispersed in carrier surface, and particle is mainly sphere, and a small amount of irregular polyhedrons is arranged, and average-size is 4 – 6nm.Fig. 6 is seen in chromatography, and reaction result is seen table 1.
Embodiment 3:
Take by weighing the 1g Alpha-alumina and be impregnated into the Pd (OAc) of 1.25mL 37.6mmol/L
2-In the acetone soln, add 4mL acetone again, stirred 3 hours; In 35 ℃ of water-baths with the ultrasonic dispersion of the energy of 200W 3 hours, 110 ℃ of dryings 4 hours, 400 ℃ of roastings 2 hours; Add the 0.070g ascorbic acid, 0.353g KBr, 0.444g PVP; 100 ℃ were reduced 60 ℃ of dryings of vacuum 10 hours 30 minutes.Transmission electron microscope photo is seen Fig. 3, can know that by figure Pd is dispersed in carrier surface, and particle is mainly sphere, and a small amount of irregular polyhedrons is arranged, and average-size is 4 – 6nm.Fig. 7 is seen in chromatography, and reaction result is seen table 1.
Embodiment 4:
Take by weighing the 1g Alpha-alumina and be impregnated into the Pd (OAc) of 1.25mL 37.6mmol/L
2-In the acetone soln, add 4mL acetone again, stirred 3 hours; In 35 ℃ of water-baths with the ultrasonic dispersion of the energy of 200W 3 hours, 110 ℃ of dryings 4 hours, 400 ℃ of roastings 2 hours; Add 1mL 0.4mol/L solution of potassium borohydride, 0.353g KBr, 0.444g PVP; 100 ℃ were reduced 60 ℃ of dryings of vacuum 10 hours 30 minutes.Transmission electron microscope photo is seen Fig. 4, can know that by figure Pd is dispersed in carrier surface, and particle is mainly sphere, and a small amount of irregular polyhedrons is arranged, and average-size is 3 – 5nm.Fig. 8 is seen in chromatography, and reaction result is seen table 1.
Table 1: the catalytic performance of embodiment catalyst in the reaction of CO gas phase carbonylation producing oxalic ester