WO2014147161A1 - Method for preparation of acetonitrile from ethanol and ammonia by amination-dehydrogenation - Google Patents

Abstract

The invention discloses a method for preparation of acetonitrile from ethanol and ammonia by amination-dehydrogenation using cobalt oxide supported on SiO₂ as catalyst.

Description

METHOD FOR PREPARATION OF ACETONITRILE FROM ETHANOL AND AMMONIA BY AMINATION-DEHYDROGENATION

The invention discloses a method for preparation of acetonitrile from ethanol and ammonia by amination-dehydrogenation using cobalt oxide supported on Si0₂ as catalyst.

BACKGROUND OF THE INVENTION

Acetonitrile is an important fine chemical product which has been widely used as synthetic intermediate for pharmaceutical, agricultural, and functional material chemicals. It is also used as a general purpose solvent for many compounds and as mobile phase in high- performance liquid chromatographic. Consequently the global yearly demand for acetonitrile is currently around 70Ό00 tons, and is expected to rise by the 3 to 4% per year. Nowadays, the main source for acetonitrile is as a by-product of acrylonitrile synthesis, the latter being obtained by propylene ammoxidation. With the increasing demand, it is difficult to meet the need in the future to obtain acetonitrile only from the production of acrylonitrile. The crisis of the fibers market in 2009 led to the shut-down of several acrylonitrile plants, which had the consequence of a shortage of acetonitrile market supply. This made the industry aware of the fact that alternative sources for acetonitrile production are mandatory. Furthermore, the production of acetonitrile as a by-product of acrylonitrile has the disadvantages of concomitant formation of hydrogen cyanide, which is toxic and is preferably therefore avoided, and of difficulty in separation of the crude product.

In the past, several routes for acetonitrile synthesis have been investigated, such as

(i) the ethanol or ethane ammonolysis,

(ii) the methanol or methane hydrocyanation,

(iii) the dehydration of acetamide, the latter obtained by reaction between ammonia and acetic acid,

(iv) the direct reaction of CO with ammonia and hydrogen, and

(v) the ethane or ethanol ammoxidation as disclosed in Kulkarni et al. in J. Chem. Soc.

Chem. Comm. (1994) 273.

Among all the raw materials ethanol becomes the first choice because it can provide a process which avoids the concomitant formation of high toxic hydrogen cyanide and gives high quality acetonitrile. Two approaches called amination-dehydrogenation and ammoxidation use ethanol as starting material, however, only amination-dehydrogenation can meet the need of avoiding formation of high toxic hydrogen cyanide. Y. Zhang et al. in Catalysis Communications 2009, 10 1454-1458, disclose Co₂o.i/gamma- AI₂O₃ and Coi₉.₉Ni₃.o/gamma-Al₂0₃ catalyst for the amination-dehydrogenation of ethanol to acetonitrile. The catalyst was prepared by a kneading method. The catalyst showed decreasing selectivity over reaction time, the yield of acetonitrile dropped to ca. 82%, and proved to be fragile during the course of regeneration.

Feng et al. in Catal Lett 2011, 141, 168-177, disclose for preparation of another AI₂O₃- supported cobalt-nickel oxide catalyst the use of a coprecipitation-kneading method instead of the kneading method disclosed by Zhang et al. for improving the mechanical strength of the catalyst. The catalyst showed activity, selectivity and lifetime comparable to the one prepared by the kneading method, but had improved mechanical strength. The yield was 92.6%.

Unfortunately, the catalyst had to be on stream for no less than about 40 h in order to reach its optimum state. Furthermore, carbon deposition on the catalyst and formation of metal carbides from the active species led to deterioration of the catalyst in the catalytic run. Hu et al. in Reac Kinet Mech Cat 2012, 106, 127-139, disclose other catalysts used for the gas-phase amination-dehydrogenation including copper oxide deposited over alumina. The authors obtained almost total conversion of ethanol at 290°C, with 92.6% selectivity to acetonitrile, using a feed ratio NF^/ethanol equal to 7. It is important to note that the catalyst was pre-reduced with H₂/N₂ at 250°C. The optimal reaction temperature is claimed to be between 270 and 290°C. However, no mention is made to the catalyst behavior during prolonged experiments.

There was a need for a an environmentally friendly process with reduced hazardousness with respect to concomitant HCN formation in the conventional processes for production of acetonitrile, which does not require the catalyst to be on stream for a long time, which provides good selectivity with regard to acetonitrile, and wherein the catalyst is readily available and can be efficiently regenerated. In the present invention, we report the use of a catalyst of Co oxide/Ni oxide supported over silica for the amination-dehydrogenation of ethanol to acetonitrile showing high performance in terms of both selectivity and yield, the overall yield achieved is above 95% with selectivity also above 95%, and therefore the yield is higher than the yield reported by Feng et al. for their catalyst based on the Co oxide/Ni oxide supported over alumina.

According to Hu et al. in Reac Kinet Mech Cat 2012, 106, 127-139, acidity is needed when using cobalt catalyst in order to accelerate the reaction of dehydration of the intermediate 1- aminoethanol into the imine for ethanol amination-dehydrogenation into acetonitrile (see scheme 1 in this literature). Therefore the prior art focuses on systems made of the active species (either Co, Cu, Ni, or combination of these elements) dispersed over alumina, which is a support having the required acidic properties. Since according to G.Busca, Phys. Chem. Chem. Phys., 1999, 1, 723-736, silica is a support holding only weak or medium weak acidic sites it was unexpected, that a catalyst using silica as support would allow obtaining high performance in comparison to a catalyst using alumina with the required acidity as support.

Rausch et al. Journal of Catalysis 2008, 253, 111-118, disclose a Co-silica catalyst for Gas- phase hydroamination of ethanol and ammonia. Acetonitrile is observed only as byproduct. The catalyst is used in the presence of a large excess of hydrogen, and rapid deactivation of the catalyst was observed in the absence of hydrogen. Rausch et al. shows, that the hydrogen reduces the cobalt oxide to metallic cobalt at elevated temperatures and it is assumed that metallic Co is the catalytically active species. In the conclusions Rausch et al. discloses, that ethanol conversion and selectivity depend strongly on the presence of hydrogen. Without hydrogen, a reversible deactivation occurs that can be ascribed to an ammonia-cobalt interaction, such as strong chemisorption or formation of nitrides. Carbon-containing species and carbonaceous deposits result in decreased catalyst activity as well.

Therefore Rausch et al. discourages the skilled person reading his disclosure to decrease the level of hydrogen when using Co/Si0₂ catalysts for the conversion of ethanol. In the case of the instant invention, which is an amination-dehydrogenation reaction of ethanol, hydrogen is produced in stoichiometric amount as shown by the reaction equation (1),

C₂H₅OH + NH₃ -> CH₃CN + H₂0 + 2 H₂ (1) therefore it is present it noticeably less amounts than in the hydroamination reaction disclosed by Rausch et al.

No hint is given by Rausch et al, that Co/Si0₂ catalysts can be used to produce acetonitrile from ethanol by amination-dehydrogenation in high yields and high selectivity.

Furthermore XPS measurements of the catalyst used in instant invention shows that Co is present in oxidized form only, no metallic cobalt can be detected. Therefore the active species can only be Co in oxidized form.

Ethylamine was never formed in the experiments of instant invention, even in experiments with 4% hydrogen or with 10% hydrogen in the feed mixture. The addition of hydrogen in the feed mixture prolongs the time where the catalyst is active and can serve for regeneration purpose.

SUMMARY OF THE INVENTION

Subject of the invention is a method (Ml) for preparation of acetonitrile from ethanol and ammonia;

the method (Ml) comprises a reaction (MIReac) between compound (ETH) and ammonia, the reaction (MIReac) is done by contacting compound (ETH) and ammonia with a catalyst (C) at a temperature (ContactTemp); compound (ETH) consists of from 90 to 100 wt% of ethanol and from 0 to 10 wt% of water, the wt% being based on the total weight of compound (ETH), and the amount of ethanol and water adding up to 100 wt%>; catalyst (C) is a cobalt oxide on a support (S), which contains from 0 to 5 wt%> of Ni in form of a nickel oxide, the wt% being based on the total weight of catalyst (C); the support (S) is Si0₂; temperature (ContactTemp) is from 320 to 440°C.

DETAILED DESCRIPTION OF THE INVENTION

In this text, the following meanings are used, if not otherwise stated:

conv. conversion; W/F is a ratio between the weight of a catalyst and the volumetric flow rate of a gas with the unit [(g*s)/mL];

"wt%", "% by weight" and "weight-%" are used synonymously and mean percent by weight. Preferably, compound (ETH) consists of from 94 to 100 wt% of ethanol and from 0 to 6 wt% of water, the wt% being based on the total weight of compound (ETH), and the amount of ethanol and water adding up to 100 wt%;

more preferably, compound (ETH) is the ethanol-water-azeotrope with 95.6 wt% EtOH and 4.4 wt% H₂0.

Preferably, from 1 to 10 mol equivalents, more preferably from 2 to 7 mol equivalents, even more preferably from 3 to 6 mol equivalents of ammonia are used, the mol equivalents being based on the molar amount of ethanol.

Preferably, in reaction (MIReac) compound (ETH) and ammonia are present in form of a mixture (MlMix), mixture (MlMix) comprises compound (ETH), ammonia and a compound (IG);

compound (IG) is an inert gas.

Preferably, compound (IG) is selected from the group consisting of steam, argon, nitrogen, carbon dioxide, helium and mixtures thereof,

more preferably of nitrogen, carbon dioxide, helium and mixtures thereof.

More preferably, mixture (MlMix) comprises from 0.5 to 20% of compound (ETH) and from 1 and 50% of ammonia,

even more preferably from 1 to 10% compound (ETH) and from 1 to 30% ammonia;

especially from 2 to 8% compound (ETH) and from 20 to 30% ammonia;

preferably any of these mixtures (MlMix) consist of compound (ETH), ammonia and

compound (IG), i.e.

in any of these mixtures (MlMix), the amount of compound (ETH), of ammonia and of

compound (IG) add up the 100%, the % being molar % based on the total molar amount of mixture (MlMix).

In a particular embodiment, mixture (MlMix) further comprises H₂; preferably, mixture (MlMix) comprises from 0.5 to 20% of compound (ETH), from 1 and

50% of ammonia and from 1 to 15 % H₂,

more preferably from 1 to 10% compound (ETH), from 1 to 30% ammonia and from 2 to 15

% H₂;

even more preferably from 2 to 8% compound (ETH), from 20 to 30% ammonia and from 3 to 12 % H₂;

preferably any of these mixtures (MlMix) consist of compound (ETH), ammonia, compound (IG) and H₂, i.e.

in any of these mixtures (MlMix) comprising H₂, the amount of compound (ETH), of

ammonia, of H₂ and of compound (IG) add up the 100%, the % being molar % based on the total molar amount of mixture (MlMix).

In another particular embodiment, mixture (MlMix) further comprises 0₂;

preferably, mixture (MlMix) comprises from 0.5 to 20% of compound (ETH), from 1 and 50% of ammonia and from 1 to 15 % 0₂,

more preferably from 1 to 10% compound (ETH), from 1 to 30% ammonia and from 2 to 12 % 0₂;

even more preferably from 2 to 8% compound (ETH), from 20 to 30% ammonia and from 2 to 8 % 0₂;

preferably any of these mixtures (MlMix) consist of compound (ETH), ammonia, compound (IG) and 0₂, i.e.

in any of these mixtures (MlMix) comprising 0₂, the amount of compound (ETH), of

ammonia, of 0₂ and of compound (IG) add up the 100%, the % being molar % based on the total molar amount of mixture (MlMix).

Preferably, the amount of Co in catalyst (C) is from 5 to 25 wt% and the amount of Ni in catalyst (C) is from 0 to 5 wt%;

more preferably, the amount of Co in catalyst (C) is from 5 to 23 wt% and the amount of Ni in catalyst (C) is from 0 to 5 wt%;

more preferably, the amount of Co in catalyst (C) is from 5 to 23 wt% and the amount of Ni in catalyst (C) is from 1 to 5 wt%;

the wt% are based on the total weight of catalyst (C). In particular embodiments, the amount of Co in catalyst (C) is 8 or 19.9 wt% and the amount of Ni in catalyst (C) is 0 or 3 wt%;

more in particular,

the amount of Co in catalyst (C) is 19.9 wt% and the amount of Ni in catalyst (C) is 0 wt%; or

the amount of Co in catalyst (C) is 19.9 wt% and the amount of Ni in catalyst (C) is 3 wt%; or

the amount of Co in catalyst (C) is 8 wt% and the amount of Ni in catalyst (C) is 0 wt%. even more in particular,

the amount of Co in catalyst (C) is 19.9 wt% and the amount of Ni in catalyst (C) is 3 wt%;

the wt% are based on the total weight of catalyst (C).

The cobalt in the cobalt oxide and the nickel in the nickel oxide can be in any possible oxidation state.

Preferably, cobalt oxide is selected from the group consisting of CoO, Co₃0₄, Co₂0₃ and mixtures thereof; more preferably, cobalt oxide is selected from the group consisting of CoO, Co₃0₄ and mixtures thereof. Preferably, nickel oxide is selected from the group consisting of NiO and Ni₂0₃, more preferably from nickel oxide is NiO.

Preferably in any of the above mentioned catalysts (C), catalyst (C) consists of cobalt oxide, support (S) and optionally nickel oxide.

The contact of compound (ETH) and ammonia with a catalyst (C) in the reaction (MIReac) is done preferably in a reactor containing the catalyst.

F in ratio W/F is the total inlet flow rate of gas, i.e. of compound (ETH) and ammonia or of mixture (MIMix) respectively, into the reaction (MIReac), i.e. into the reactor.

F in ratio W/F is measured and/or calculated at room temperature.

W in ratio W/F is the weight of catalyst (S).

Preferably, ratio W/F between the weight of the catalyst (C) and the volumetric flow rate of mixture (MIMix) is of from 0.1 to 10 (g*s)/mL, more preferably of from 0.3 to 5 (g*s)/mL, even more preferably of from 0.5 to 3 (g*s)/mL, especially of from 0.5 to 2 (g*s)/mL. A commonly used ratio (W/F) is 1 (g*s)/mL without limiting the invention to this specific value.

Preferably, temperature (ContactTemp) is from 330 to 420°C; more preferably 340 to 400°C.

Temperature (ContactTemp) may be held constant in method (Ml), temperature

(ContactTemp) may change during method (Ml). For instance, the reaction (MlReac) may be run for a certain time at temperature (ContactTemp 1), and then for a given time at temperature (ContactTemp2) different from temperature (ContactTemp 1). Alternatively, the temperature may be modified continuously during method (Ml).

Preferably, the compound (ETH) and the ammonia, or the mixture (Ml Mix) respectively, are preheated before contacted with catalyst (C).

More preferably, the compound (ETH) and the ammonia, or the mixture (Ml Mix)

respectively, are preheated before contacted with catalyst (C) to a temperature

(PreHeatTemp), temperature (PreHeatTemp) is from 50 to 400°C, more preferably from 100 to 300°C, even more preferably from 150 to 250°C, even more preferably from 175 to 225°C.

Preferably, reaction (MlReac) is done at a pressure of from atmospheric pressure to 10 bar, more preferably of from atmospheric pressure to 5 bar, even more preferably at from atmospheric to 2 bar. The pressure will depend on the reaction temperature chosen, and whether or not the reaction system is a closed system.

The method (Ml) of the invention can be done either continuously, semi-continuous ly, or batch wise; preferably it is continuously.

When method (Ml) is done batch wise the reaction time is preferably from 30 min to 72 h, more preferably from 1 h to 48 h, even more preferably from 2 h to 24 h.

Acetonitrile can be analyzed by standard techniques such as gas chromatography. The

analysis can be done continuously during method (Ml), i.e. online with reaction

(MlReac).

Acetonitrile can be isolated by standard techniques such as distillation. Further subject of the invention is method (Ml) as defined above, wherein the catalyst (C) has been prepared by 5 steps;

step (Catl) dissolving a salt (SA) in water,

step (Cat2) adding support (S) to obtain a suspension,

step (Cat3) stirring the suspension obtained in step (Cat2) for a time (TimeCat), step (Cat4) removing the water to obtain a solid,

step (Cat5) calcination of the solid; with catalyst (C) and support (S) as defined above, also with all its preferred embodiments; salt (SA) is a water soluble cobalt salt, and if catalyst (C) contains Ni, then salt (SA) contains in addition to said water soluble cobalt salt a water soluble nickel salt;

time (TimeCat) is from 1 min to 24 h. Preferably, salt (SA) is selected from the group consisting of sulphate, nitrate, carbonate, citrate and oxalate of cobalt and mixtures thereof;

and if catalyst (C) contains Ni, then salt (SA) contains in addition to said cobalt salt a nickel salt, the nickel salt being selected from the group consisting of sulphate, nitrate, carbonate, citrate and oxalate of nickel and mixtures thereof;

more preferably, salt (SA) is cobalt nitrate, and if catalyst (C) contains Ni, then salt (SA) contains in addition to said cobalt salt nickel nitrate.

Salt (SA) can be used anhydrous form or as a hydrate, preferably as hydrate, in case of nitrate preferably as hexahydrate.

Preferably in step (Catl), salt (SA) is dissolved in water at a temperature (TempCatl),

temperature (TempCatl) is from 0 to 100 °C, more preferably from 5 to 50°C, even more preferably from 15 to 35°C. In step (Cat3) the suspension is stirred preferably at a temperature (TempCat2), temperature (TempCat2) is from 0 to 100°C, more preferably 5 to 50°C, even more preferably from 15 to 35°C.

Preferably temperature (TempCatl) and temperature (TempCat2) are identical. Preferably, time (TimeCat) is from 10 min to 12 h, even more preferably of from 30 min to 3 hours. In step (Cat4), the water can be removed by standard techniques such as distillation.

Catalyst (C) can be dried between step (Cat4) and step (Cat5). Preferably, drying is done at a temperature (TempCatDry), temperature (TempCatDry) is from 0 to 200°C, more preferably from 50 to 150°C, even more preferably from 100 to 150°C.

In step (Cat5) calcination is preferably done at temperature (TempCatCalcl) for a time

(TimeCatCalcl) and at temperature (TempCatCalc2) for a time (TimeCatCalc2);

temperature (TempCatCalcl) is from 20 to 550°C;

temperature (TempCatCalc2) is from 120 to 750°C;

time (TimeCatCalcl) is from 15 min to 24 h;

time (TimeCatCalc2) is from 15 min to 24 h.

Preferably, the temperature is changed from temperature (TempCatCalcl) to temperature (TempCatCalc2) at a rate of 5 to 15°C per min.

More preferably,

temperature (TempCatCalcl) is from 50 to 300°C,

temperature (TempCatCalc2) is from 150 to 650°C,

time (TimeCatCalcl) is from 30 min to 12 h,

time (TimeCatCalc2) is from 1 h to 12 h.

Even more preferably,

temperature (TempCatCalcl) is from 90 to 150°C,

temperature (TempCatCalc2) is from 250 to 600°C,

time (TimeCatCalcl) is from 1 h to 6 h,

time (TimeCatCalc2) is from 1 h to 8 h.

Especially,

temperature (TempCatCalcl) is from 90 to 150°C,

temperature (TempCatCalc2) is from 400 to 600°C,

time (TimeCatCalcl) is from 1 h to 6 h, time (TimeCatCalc2) is from 1 h to 8 h.

EXAMPLES

Catalysts preparation and characterization

The support Si0₂ used was commercially available silica produced by Grace and Catalyst Carriers with the following specifications:

• Grade: 432

• Specific surface area (m²/g): 320

• Pore Volume (mL / g): 1.2

• Particle size: 30 to 100 micron

• Particle shape: granular

The support gamma- AI₂O₃ used was commercially available alumina produced by BASF with the following specifications:

• Specific surface area (m²/g) 190

• Product code: AL 3992

The source of cobalt was commercially available cobalt (II) nitrate hexahydrate with purity > 98%.

The source of copper was commercially available copper (II) nitrate trihydrate with purity > 99 %.

The source of nickel was commercially available nickel (II) nitrate hexahydrate with purity > 98%.

The amount of Co and the Cu in catalyst (C) was measured by means of ICPOES (Inductively Coupled Plasma Optical Emission Spectrometry), after treatment of the sample with microwave.

Example 1: Preparation C019.9/S1O₂

9.8107 g of cobalt nitrate hexahydrate are dissolved in 25 mL of distilled H₂0 at room temperature in a flask while stirring; after the complete dissolution of the salt, 10.0350 g of Si0₂ are added slowly. The slurry obtained is left under stirring for 1 hour. The water is subsequently removed from the flask by means of a rotary evaporator at the relative pressure of 90 kPa and at a temperature of 70°C. The solid obtained is dried in an oven at 120°C overnight. The catalyst was then calcined according to example 7. Characterization of catalysts before and after reaction by means of XPS

XPS spectra of the calcined catalyst before reaction and after reaction of ethanol to acetonitrile showed Co only in oxidized form as CoO and C0₃O₄ could be detected, but no metallic Co could be detected.

Example 2: Preparation Cos/SiC>₂

Example 1 was repeated with the sole difference, that 4.9035 g of cobalt nitrate hexahydrate instead of 9.8107 g. Example 3: Preparation CU19.5/S1O₂

Example 1 was repeated with the sole difference, that 7.9106 g of copper nitrate trihydrate instead of instead of 9.8107 g cobalt nitrate hexahydrate.

Example 4: Preparation Cui₃.₂/Si0₂

Example 1 was repeated with the sole difference, that 3.9553 g of copper nitrate trihydrate instead of 9.8107 g cobalt nitrate hexahydrate.

Example 5: Preparation of Co20Ni3/Al₂O₃

1.4914 g of nickel nitrate hexahydrate were dissolved in 5 mL of distilled H₂0 at room temperature in a flask while stirring. In another flask 9.8107 g of cobalt nitrate hexahydrate were dissolved in 25 mL of distilled H₂0. After completed the dissolution the two solutions were combined in a flask, while stirring 10.0350 g of AI₂O₃ are added. The slurry obtained was left for 1 h while stirring. The water was then removed by evaporation with a rotary vapory evaporator at the relative pressure of 90 kPa and at a temperature of 70°C. The solid obtained was dried in an oven at 120°C for one night. The catalyst was then calcined according to example 7.

Example 6: Preparation of Co20/Al₂O₃

Example 5 was repeated with the sole difference, that no nickel nitrate hexahydrate was used.

Example 7: Calcination

The sample was calcined using thermal treatment in static air in a muffle furnace, with the following temperature program:

• 120°C for 2 hours; • heating with a rate of 10°C / min to 550°C;

• 550°C for 5 hours;

• Cooling down to ambient temperature. Example 8: Preparation of Co20Ni3/SiO₂

1.4914 g of nickel nitrate hexahydrate were dissolved in 5 mL of distilled H₂0 at room temperature in a flask while stirring. In another flask 9.8107 g of cobalt nitrate hexahydrate were dissolved in 25 mL of distilled H₂0. After completed the dissolution the two solutions were combined in a flask, while stirring 10.0350 g of Si0₂ are added. The slurry obtained was left for 1 h while stirring. The water was then removed by evaporation with a rotary vapory evaporator at the relative pressure of 90 kPa and at a temperature of 70°C. The solid obtained was dried in an oven at 120°C for one night. The catalyst was then calcined according to example 7. The Co content in the catalysts prepared in examples 5, 6 and 8 was not measured but assumed to be the same as in example 1 , since the same amount of Co salt was used for preparation.

The Ni content in the catalysts prepared in examples 5 and 8 was not measured but assumed to be around 3% based on the amount of Ni salt used for preparation.

Examples 9 to 21

Reactor and analysis

The reactor is a tubular type fixed-bed reactor, made of quartz, with an internal diameter of 0.8 cm and a total length of 46 cm, fitted with a porous septum to support the catalytic bed. The catalytic bed is positioned approximately mid-height of the reactor and its place corresponds to the isothermal zone of the oven heating; here the internal reactor diameter is 1 cm. Catalyst (S) is held on a porous septum of sintered glass. Within the reactor a stainless steel pipe with 1/16" in diameter is placed, inside which is inserted a thermocouple, capable to provide the contact temperature by direct measurement inside the catalytic bed.

The feed was made of three parts: the first part was helium as inert gas and the second part was ammonia mixed with helium with a molar fraction of ammonia of 40 %.

For calculating purposes of the amount of compound (IG), the amounts of helium were added. Both were fed in form of gaseous streams and their flow rates were regulated by means of a mass-flow controller. Both were mixed together. The third part was ethanol, used in form of its azeotropic mixture of 95.6 wt% EtOH and 4.4 wt% H20, which was vaporized and added to the mixture of helium and ammonia to provide the feed mixture. Injection of the feed mixture in gaseous form occurred by means of a calibrated high precision syringe. The feed mixture was preheated to 200°C before injection. The outflow from the reactor was maintained at a temperature of 200°C by means of a heater band.

Downstream of the reactor, a valve allows regulating the flow, which was sent to an online GC (gas chromatography) analysis system and/or to a flow measurement and/or to a condensation/abatement system.

The gas chromatography apparatus is a HP 5890A with two columns:

(a) a semicapillary HP Plot U, length 30 m, internal diameter of 0.53 mm and a fixed phase of 20 micron; the maximum temperature that it can withstand is 190°C. This column is used to separate components such as ethanol, ammonia, carbon dioxide, acetaldehyde, acetonitrile and other organic compounds.

(b) The second column is an HP Molsieve semicapillary column (HP MS 5A column, a molecular sieve) of 30 m long in length, having an internal diameter of 0.53 mm; it allows working with temperatures that can reach up to 300°C. This column is aimed at the separation of oxygen, nitrogen and carbon monoxide.

The sampling system was composed by two valves, positioned inside an oven maintained at a temperature of 200°C. The valves were equipped with two calibrated loops (volume of 100 and 80 μί). Each of the valves allows passage of the outlet gas stream via the loops to one of the two colums.

The GC oven temperature is as follows: 60°C for 6.8 min, heating to 100°C at a rate of 40°C/min, 100°C for 8.5 min, heating to 130°C with 60°C/min, 130°C for 5 minutes, heating to 170°C with 60°C/min, 170°C for 8 min. Examples 9, 10, 11, 17, 18, 20 and 21 were carried out with the following conditions:

Composition of the feed mixture representing mixture (Ml Mix) was 25% ammonia, 5% ethanol (in form of its azeotropic mixture of 95.6 wt% EtOH and 4.4 wt% H₂0) and 70% helium, the % being molar % based on the total molar amount of the feed mixture. Example 14 was carried out with the following conditions:

Composition of the feed mixture representing mixture (Ml Mix) was 25% ammonia, 5% ethanol (in form of its azeotropic mixture of 95.6 wt% EtOH and 4.4 wt% H₂0), 4% H₂ and 66% helium, the % being molar % based on the total molar amount of the feed mixture.

Example 15 was carried out with the following conditions:

Composition of the feed mixture representing mixture (Ml Mix) was 25% ammonia, 5% ethanol (in form of its azeotropic mixture of 95.6 wt% EtOH and 4.4 wt% H₂0), 10% H₂ and 60% helium, the % being molar % based on the total molar amount of the feed mixture.

Example 19 was carried out with the following conditions:

Composition of the feed mixture representing mixture (Ml Mix) was 25% ammonia, 5% ethanol (in form of its azeotropic mixture of 95.6 wt% EtOH and 4.4 wt% H₂0), 4% 0₂ and 66% helium, the % being molar % based on the total molar amount of the feed mixture.

Ratio W/F was 1 (g*s)/mL.

In the experiments, the individual flow rates of the inert gas and of the ammonia was measured at room temperature, whereas the volumetric flow of compound (ETH) is calculated from the number of moles vaporized per unit time, and the number of moles is transformed into a volumetric flow by using the perfect gas law, with T being room temperature.

Results of catalytic experiments

Table 1 lists the catalysts used, contact temperatures or time of analysis, conversion and selectivity.

Examples 9, 10, 11, 17 and 21 were experiments at various contact temperatures given column (0).

Example 12, 13, 14, 15, 18, 19 and 20 were experiments were the reaction was done isothermally and the analysis was done at the times given in column (0).

Legend to Table 1 :

(0) contact temperature

(1) acetonitrile acetaldehyde

ethane

CO and C0₂

other by-products (including CH₄)

Table 1

Ex (0) Conversion Selectivity

(%) (%)

EtOH (1) (2) (3) (4) (5)

9 Co2o i3/ amma-Al₂03, prepared according to example 5

370°C 94.4 45.9 1.1 23.9 - 21.5

400°C 99.6 47.4 0.5 24.3 - 27.5

420°C 100 50.0 0.3 29.0 - 20.5

440°C 100 50.5 0 33.1 - 16.3

10 C0₁₉.9/S1O2, prepared according to example 1

300°C 28 26.1 1.9 - - 71.9

320°C 44.9 39.3 1.7 - - 59.0

350°C 94.0 93.7 0.5 - 3.3 2.5

370°C 99.6 97.0 - 3.0 -

11 C0s/SiO₂, prepared according to example 2

300°C 4.7 86.5 7.6 - - 5.9

320°C - - - - - -

350°C 89.9 89.1 0.4 1.2 6.1 3.2

370°C 98.6 92.8 - 1 6.2 -

14 C0₁₉.9/S1O2, prepared according to example 1,

isotherm at 370°C + 4% H₂

Initially 99.2 84.7 - 1.0 10.3 5.6

After 1.3 h 98.2 86.3 - 1.2 9.0 4.4

After 6 h 95.9 85.2 - 1.0 9.0 4.8

After 26.7 h 76.6 64.8 - 1.6 6.9 26.4

After 98.4 84.2 1.9 10.7 5 regeneration,

after 1.5 h 7.5 h after 99.7 82.6 2.1 9.3 7.2 regeneration

C019.9/S1O2, prepared according to example 1,

isotherm at 370°C + 10% H₂

Initially 99.6 75.4 - 1.1 15.3 10.1

After 6 h 98.4 68.6 - 1.3 13.8 17.6

After 18.7 h 99.2 61.2 - 1.0 19.0 19.8

Co2o/gamma-Al₂C>3, prepared according to example 6

350°C 95.7 37.1 1.6 21.2 - 40.0

370°C 98.2 41.6 1.4 27.7 - 29.3

400°C 99.1 58.8 0.9 29.6 - 10.8

C0i9.9 i3/SiO2, prepared according to example 8,

isotherm at 350°C

Initially 99.4 94.9 - 2.4 2.8 -

After 4 h 99.4 96.0 - 1.7 2.5 -

C019.9/S1O2, prepared according to example 1, isotherm at 370°C + 4% 0₂

Initially 98.3 87.2 0.6 0.6 12.0

After 12.7 h 96.1 90.2 0.7 1.0 8.1

CU19.5/S1O2, prepared according to example 3,

isotherm at 270°C

initially 53.7 73.2 0.2 0.6 - 25.9

After 1.5 h 10.0 31.3 3.0 0.2 - 65.5

CU13.5/S1O2, prepared according to example 4

320°C 26.5 28.4 0.6 0.3 - 70.7

430°C 61.9 4.8 0.4 16.2 78.6

Claims

1. Method (Ml) for preparation of acetonitrile from ethanol and ammonia;

the method (Ml) comprises a reaction (MIReac) between compound (ETH) and ammonia, the reaction (MIReac) is done by contacting compound (ETH) and ammonia with a catalyst (C) at a temperature (ContactTemp); compound (ETH) consists of from 90 to 100 wt% of ethanol and from 0 to 10 wt% of water, the wt% being based on the total weight of compound (ETH), and the amount of ethanol and water adding up to 100 wt%; catalyst (C) is a cobalt oxide on a support (S), which contains from 0 to 5 wt% of Ni in form of a nickel oxide, the wt% being based on the total weight of catalyst (C); the support (S) is Si0₂; temperature (ContactTemp) is from 320 to 440°C.

2. Method (Ml) according to claim 1, wherein

compound (ETH) consists of from 94 to 100 wt% of ethanol and from 0 to 6 wt% of water.

3. Method (Ml) according to claim 1 or 2, wherein

from 1 to 10 mol equivalents of ammonia are used, the mol equivalents being based on the molar amount of ethanol.

4. Method (Ml) according to one or more of claims 1 to 3, wherein

in reaction (MIReac) compound (ETH) and ammonia are present in form of a mixture

(Ml Mix), mixture (Ml Mix) comprises compound (ETH), ammonia and a compound (IG);

compound (IG) is an inert gas.

5. Method (Ml) according to one or more of claims 1 to 4, wherein

compound (IG) is selected from the group consisting of steam, argon, nitrogen, carbon

dioxide, helium and mixtures thereof.

6. Method (Ml) according to claim 4 or 5, wherein

mixture (MlMix) comprises from 0.5 to 20% of compound (ETH) and from 1 and 50% of ammonia.

7. Method (Ml) according to one or more of claims 4 to 6, wherein

mixture (MlMix) consists of compound (ETH), ammonia and compound (IG).

8. Method (Ml) according to claim 4 or 5, wherein

mixture (Ml) comprises H₂.

9. Method (Ml) according to 8, wherein

mixture (MlMix) comprises from 0.5 to 20% of compound (ETH), from 1 and 50% of

ammonia and from 1 to 15 % H₂.

10. Method (Ml) according to claim 8 or 9, wherein

mixture (MlMix) consists of compound (ETH), ammonia, compound (IG) and H₂.

11. Method (Ml) according to claim 4 or 5, wherein

mixture (Ml) comprises 0₂.

12. Method (Ml) according to 11, wherein

In another particular embodiment, mixture (MlMix) comprises from 0.5 to 20% of compound (ETH), from 1 and 50% of ammonia and from 1 to 15 % 0₂.

13. Method (Ml) according to claim 11 or 12, wherein

mixture (MlMix) consists of compound (ETH), ammonia, compound (IG) and 0₂.

14. Method (Ml) according to one or more of claims 1 to 13, wherein

the amount of Co in catalyst (C) is from 5 to 25 wt% and the amount of Ni in catalyst (C) is from 0 to 5 wt%;

the wt% are based on the total weight of catalyst (C).

15. Method (Ml) according to one or more of claims 1 to 14, wherein temperature (ContactTemp) is from 330 to 420°C.

16. Method (Ml) according to one or more of claims 1 to 15, wherein method (Ml) is done continuously.