CN101559370A - Cu-Cr series ethyl acetate catalyst added with modified additive and manufacturing method thereof - Google Patents

Abstract

The method belongs to the Cu-Cr series ethyl acetate catalyst added with modifying auxiliary agent and its manufacturing method. The catalyst exists in the form of composite metal oxides, and the mass percentages of each component in the total mass of the catalyst are: 25-55% Cu, 10-25% Cr, 0-10% Mg, 0-10% Zr, and the balance is oxygen. Among them, the additives Mg and Zr cannot be 0 at the same time. Add an alkaline precipitant to the uniformly mixed salt solution containing Cu, Cr, Mg and Zr in proportion to the stirring state, the pH value of the precipitation process is controlled at 6-10, and the aging time is 0.2-20h; the obtained precipitate is filtered, Wash with water until the filtrate is neutral. After drying at 80-130° C. for 4-15 hours, calcining at 300-500° C. for 2-8 hours to obtain the catalyst precursor. It has higher activity and selectivity than existing catalysts.

Description

Add the Cu-Cr series ethyl acetate catalyst of modification assistant and manufacture method

technical field

The method belongs to a manufacturing method for a specific synthetic chemical reaction catalyst, in particular a Cu-Cr ethyl acetate catalyst and a manufacturing method adding a modification auxiliary agent.

Background technique

Ethyl acetate is a commonly used organic solvent, which is widely used in the production of products such as fragrances, medicines and thinners. As a high-grade solvent, ethyl acetate will replace various low-grade solvents that seriously pollute the air. According to the forecast of authoritative organizations, the average annual growth rate of global demand for ethyl acetate can reach 4.7%.

There are mainly four kinds of methods for industrially synthesizing ethyl acetate: the one is the catalytic esterification method of traditional acetic acid and ethanol; The direct synthesis method in the presence of an acid catalyst; the fourth is the one-step catalytic dehydrogenation method of ethanol.

The raw material for the one-step preparation of ethyl acetate is ethanol. Because ethanol can be obtained from plant fermentation, it does not have to rely on non-renewable resources such as petroleum. It is a green chemical product that meets the requirements of sustainable development, and the raw material for ethanol preparation can be regenerated , so that the research of preparing various downstream products with ethanol as raw material is gradually attracting people's attention. From the perspective of investment cost, using ethanol as a raw material is more economical, non-toxic and non-polluting, and is especially suitable for combining with low-cost fermentation ethanol devices.

The catalysts for the preparation of ethyl acetate by the ethanol method mainly include Cu-Zn-Al and Cu-Cr systems. The former has not yet been successfully industrialized, and the latter has established several sets of large-scale ethyl acetate production of 10,000 tons all over the world. device.

Although the Cu-Zn-Al series catalyst has higher conversion rate, there are following problems: the one, selectivity is not high enough, and the selectivity of ethyl acetate is lower than 93%, as article Journal of Catalysis 212 (2002) 207-215 and Chinese patent CN1062304A mentions; the 2nd, contain more butanone in the by-product, and butanone and ethyl acetate can form azeotrope, have had a strong impact on the purifying and refining process of product.

Although the existing Cu-Cr series catalysts have high selectivity, reaching 95-98%, but the single-pass conversion activity of the catalyst is low, only 30-35%, resulting in high production cost of ethyl acetate. Patent CN1644239 proposes to use Ag as a promoter to improve the performance of Cu-Cr catalyst, the activity is improved, but the selectivity of ethyl acetate is low, about 90%.

Contents of the invention

The object of the present invention is to provide a kind of novel high-performance Cu-Cr system ethyl acetate catalyst and manufacture method of adding modifying auxiliary agent, this catalyst is auxiliary agent with metal oxides such as Mg, Zr, has higher than existing catalyzer activity and selectivity.

The Cu-Cr series ethyl acetate catalyst of the present invention with the addition of modifying additives exists in the form of catalyst composite metal oxides, and the mass percentages of each component accounting for the total mass of the catalyst are as follows:

Cu 25～55%,

Cr 10～25%,

Mg 0～10%,

Zr 0～10%,

The balance is oxygen.

Among them, the additives Mg and Zr cannot be 0 at the same time.

In the catalyst manufacturing method of the present invention, the salt solution containing Cu, Cr, Mg and Zr is uniformly mixed in proportion to adding an alkaline precipitating agent in the state of stirring, the pH value of the precipitation process is controlled at 6 to 10, and the aging time is 0.2 to 10. 20h; the obtained precipitate was filtered and washed with water until the filtrate was neutral. After drying at 80-130° C. for 4-15 hours, calcining at 300-500° C. for 2-8 hours to obtain the catalyst precursor.

The auxiliary agents Mg and Zr can also be added to the Cu-Cr catalyst by the equal volume impregnation method. The auxiliary agent can be added as any one or both of the soluble salts of Mg and Zr, and converted into corresponding oxides after roasting.

The catalyst activation method can adopt the usual method, which is low-temperature reduction activation at 250°C, the activation atmosphere is a mixed flow of 10% H ₂ -90% N ₂ , and the reduction time is 3 hours.

The activity evaluation of the catalyst was carried out in a fixed-bed microreactor. The reactor was made of a stainless steel tube with a length of 300 mm and an inner diameter of 8 mm. The catalyst loading was 1 mL (20-40 mesh). Before the activity evaluation begins, the catalyst needs to be reduced. After the reduction, the raw material ethanol is sent to the preheater for vaporization through a high-pressure micro-metering pump. The vaporized ethanol enters the reactor for reaction, and the reaction product is analyzed by gas chromatography.

Detailed ways

Comparative Example 1: Preparation of Cu-Cr-O Catalyst

19.2 grams of Cu(NO ₃ ) ₂ 6H ₂ O and 25.9 grams of Cr(NO ₃ ) ₃ 9H ₂ O (Cu/Cr molar ratio 1:1) were prepared into a uniform mixed salt solution, and the concentration of 0.5N Sodium hydroxide solution was added to the reaction kettle in parallel under stirring, and the pH value of the control system was 8. After the precipitation was completed, aged for 5 hours, filtered, washed with water until filtered and neutral, dried at 110°C for 5 hours, and roasted at 400°C 2h, the precursor body was obtained. The fresh Cu-Cr-O catalyst was prepared by reducing the precursor in situ at 250°C for 3 h in a 10% H ₂ -90% N ₂ mixed gas stream.

Continuously feed ethanol into a tubular reactor equipped with a fresh catalyst, the liquid volume space velocity is 0.6h ^-1 , the reaction temperature is 220°C, the conversion rate of ethanol is measured to be 30%, the selectivity of ethyl acetate is 80%, and the ethyl acetate selectivity is 80%. Aldehyde selectivity was 13%.

Comparative example 2: Cu-Cr-O catalyst preparation

The preparation method is the same as that of Comparative Example 1, but in this example Cu: Cr:=0.5:1 (molar ratio), the precipitation agent is 0.75N sodium carbonate aqueous solution, and the pH of the control solution is 7.

Pass ethanol continuously into the tubular reactor equipped with fresh Cu-Cr-O catalyst, the liquid volume space velocity is 0.6h ^-1 , the reaction temperature is 220°C, the measured ethanol conversion rate is 25%, ethyl acetate selects The specificity is 70%, and the selectivity to acetaldehyde is 15%.

Comparative example 3: Cu-Cr-O catalyst preparation

With comparative example 1, but in this example Cu: Cr:=2: 1 (molar ratio), precipitation agent is 1N ammoniacal liquor, the pH of control solution is 10, and catalyst roasting condition is 300 ℃ 10h.

Pass ethanol continuously into the tubular reactor equipped with fresh Cu-Cr-O catalyst, the liquid volume space velocity is 0.6h ^-1 , the reaction temperature is 220°C, and the conversion rate of ethanol is measured to be 36%. The specificity is 74%, and the selectivity to acetaldehyde is 11%.

Embodiment 1: Cu-Cr-Mg-O catalyst preparation

Dissolve 20 grams of Mg(NO ₃ ) ₂ ·6H ₂ O in distilled water, load it on the 15 grams of Cu-Cr-O catalyst precursor prepared by the method in Comparative Example 2 according to the equal volume impregnation method, and roast at 450 ° C After 4h, the catalyst precursor was obtained. Fresh Cu-Cr-Mg-O catalysts were prepared after the body was reduced in situ at 250° C. for 3 hours in a 10% H ₂ -90% N ₂ mixed gas stream.

The ethanol was continuously passed into the tubular reactor equipped with fresh Cu-Cr-Mg-O catalyst, the liquid volume space velocity was 0.6h ^-1 , the reaction temperature was 230°C, the conversion rate of ethanol was measured to be 48%, and the ethyl acetate Ester selectivity is 94%, acetaldehyde selectivity is 2%.

Embodiment 2: Cu-Cr-Zr-O catalyst preparation

6 g of ZrOCl ₂ ·8H ₂ O was dissolved in distilled water, and supported on 15 g of Cu-Cr-O catalyst precursor prepared by the method in Comparative Example 3 according to the equal volume impregnation method. After calcination at 400°C for 8 hours, the catalyst precursor was obtained. Fresh Cu-Cr-Zr-O catalysts were prepared after the body was reduced in situ at 250° C. for 3 hours in a 10% H ₂ -90% N ₂ mixed gas stream.

Pass ethanol continuously into the tubular reactor equipped with fresh Cu-Cr-Zr-O catalyst, the liquid volume space velocity is 0.6h ^-1 , the reaction temperature is 230°C, the conversion rate of ethanol is measured to be 43%, and the ethyl acetate Ester selectivity is 90%, acetaldehyde selectivity is 3%.

Embodiment 3: Cu-Cr-Mg-Zr-O catalyst preparation

3 g of ZrOCl ₂ ·8H ₂ O and 10 g of Mg(NO ₃ ) ₂ ·6H ₂ O were dissolved in distilled water, and supported on 15 g of the catalyst precursor prepared by the method in Comparative Example 1 by equal volume impregnation. After calcining at 400°C for 2 hours, the catalyst precursor was obtained. Fresh Cu-Cr-Mg-Zr-O catalyst was obtained after the body was reduced in situ at 250° C. for 3 hours in a 10% H ₂ -90% N ₂ mixed gas stream.

Pass ethanol continuously into the tubular reactor equipped with fresh Cu-Cr-Mg-Zr-O catalyst, the liquid volume space velocity is 0.5h ^-1 , the reaction temperature is 220°C, and the measured ethanol conversion rate is 45%. The selectivity to ethyl acetate is 96%, and the selectivity to acetaldehyde is 2%.

Embodiment 4: Cu-Cr-Mg-O catalyst preparation

Dissolve 19.2 grams of Cu(NO ₃ ) ₂ 6H ₂ O, 25.9 grams of Cr(NO ₃ ) ₃ 9H ₂ O and 2 grams of Mg(NO ₃ ) ₂ 6H ₂ O in distilled water to make a uniform mixed salt solution, While stirring, add 1N sodium hydroxide solution into the reactor at the same time and control the pH to 6. After the precipitation is complete, age for 10 hours, wash with water, filter until the filtrate is neutral, dry the filter cake at 130°C for 4 hours, and roast at 300°C After 10 hours, the precursor body was obtained. Fresh Cu-Cr-Mg-O catalysts were prepared after the body was reduced in situ at 250° C. for 3 hours in a 10% H ₂ -90% N ₂ mixed gas stream.

Pass ethanol continuously into the tubular reactor equipped with fresh Cu-Cr-Mg-O catalyst, the liquid volume space velocity is 0.6h ^-1 , the reaction temperature is 220°C, the conversion rate of ethanol is measured to be 50%, and the ethyl acetate Ester selectivity is 90%, acetaldehyde selectivity is 3%.

Embodiment 5: Cu-Cr-Mg-O catalyst preparation

Dissolve 19.2 grams of Cu(NO ₃ ) ₂ 6H ₂ O, 25.9 grams of Cr(NO ₃ ) ₃ 9H ₂ O and 7 grams of Mg(NO ₃ ) ₂ 6H ₂ O in distilled water to prepare a uniform mixed salt solution, Under stirring, add 1N sodium hydroxide solution into the reaction kettle at the same time, control the pH to 7, after the precipitation is completed, age for 20 hours, wash with water, filter until the filtrate is neutral, dry the filter cake at 80°C for 15 hours, and roast at 400°C 6h, the precursor body was obtained. Fresh Cu-Cr-Mg-O catalysts were prepared after the body was reduced in situ at 250° C. for 3 hours in a 10% H ₂ -90% N ₂ mixed gas stream.

The ethanol was continuously passed into the tubular reactor equipped with fresh Cu-Cr-Mg-O catalyst, the liquid volume space velocity was 0.6h ^-1 , the reaction temperature was 220°C, the conversion rate of ethanol was measured to be 49%, and the ethyl acetate Ester selectivity is 92%, acetaldehyde selectivity is 3%.

Embodiment 6: Cu-Cr-Zr-O catalyst preparation

Dissolve 19.2 grams of Cu(NO ₃ ) ₂ ·6H ₂ O and 25.9 grams of Cr(NO ₃ ) ₃ ·9H ₂ O and 0.5 grams of ZrOCl ₂ ·8H ₂ O in distilled water to make a uniform mixed salt solution, and stir 1N Na ₂ CO ₃ -NaOH mixed alkali solution was fed into the reaction kettle at the same time, and the pH value of the system was controlled to be 7. The rest of the subsequent preparation method was the same as that of Comparative Example 1 to obtain a fresh Cu-Cr-Zr-O catalyst.

The ethanol was continuously passed into the tubular reactor equipped with fresh Cu-Cr-Zr-O catalyst, the liquid volume space velocity was 0.6h ^-1 , the reaction temperature was 220°C, the conversion rate of ethanol was measured to be 47%, and the ethyl acetate Ester selectivity is 85%, acetaldehyde selectivity is 3%.

Embodiment 7: Cu-Cr-Zr-O catalyst preparation

Dissolve 19.2 grams of Cu(NO ₃ ) ₂ 6H ₂ O and 25.9 grams of Cr(NO ₃ ) ₃ 9H ₂ O and 1.5 grams of ZrOCl ₂ 8H ₂ O in distilled water to make a uniform mixed salt solution, stirring Add 0.75N Na ₂ CO ₃ -NaOH mixed alkali solution into the reaction kettle at the same time, control the pH value of the system to 10, age for 0.2h, and roast at 600°C for 6h. -Cr-Zr-O catalyst.

The ethanol was continuously passed into the tubular reactor equipped with fresh Cu-Cr-Zr-O catalyst, the liquid volume space velocity was 0.6h ^-1 , the reaction temperature was 220°C, the conversion rate of ethanol was measured to be 47%, and the ethyl acetate Ester selectivity is 82%, acetaldehyde selectivity is 3%.

Claims (3)

1. a kind of Cu-Cr system ethyl acetate catalyst that adds modification aid, each component accounts for the mass percentage composition of catalyst gross mass as follows: Cu 25～55%, Cr 10～25%, Mg 0～10%, Zr 0～10%, The balance is oxygen. Among them, the additives Mg and Zr cannot be 0 at the same time. 2. the manufacture method of the Cu-Cr system ethyl acetate catalyst that adds modifying auxiliary agent according to claim 1 is characterized in that the salt solution that will contain Cu, Cr, Mg and Zr is added alkali under the state of stirring in proportion Precipitating agent, the pH value of the precipitation process is controlled at 6-10, and the aging time is 0.2-20h; the obtained precipitate is filtered and washed with water until the filtrate is neutral. After drying at 80-130° C. for 4-15 hours, calcining at 300-600° C. for 2-10 hours to obtain the catalyst precursor. 3. the manufacture method of the Cu-Cr series ethyl acetate catalyst that adds modified auxiliary agent according to claim 1 is characterized in that auxiliary agent Mg and Z utilize equal volume impregnation method to add in Cu-Cr catalyst, auxiliary agent is with Mg, Either one or both of the soluble salts of Zr are added at the same time, and converted into corresponding oxides after roasting.