CA1252801A - Conversion process of methanol or dimethylether to olefins - Google Patents

Abstract

The invention relates to a process for the manufacture of olefins containing 2 to 5 carbon atoms per molecule, from a reagent which is methanol or dimethyl ether or a mixture thereof; the process is carried out in the presence of at least one catalyst based on dealuminized mordenite having an Si / Al atomic ratio greater than 80, an Na 2 O content of less than 0.1% by weight, a specific surface, after shaping, between 390 and 600m2 / g, a total pore volume between 0.540 and 0.650cm3 / g, a pore volume, for pores with a diameter greater than 10nm (10 x 10-9m) between 0.350 and 0.550cm3 / g, and carried out by passing the diluted reagent through a carrier gas or by steam; the process is characterized in that, after having separated the olefins from the reactant and from the diluent from the reactant (gas or water vapor), the olefins are fractionated so as to collect on the one hand a cut containing essentially hydrocarbons at 2 and 3 carbon atoms per molecule, and on the other hand a cut containing for the most part higher olefins containing at least 4 carbon atoms per molecule, this latter cut being recycled at least partly in the reaction zone. This process allows the manufacture of olefins containing 2 to 5 carbon atoms from starting materials different from those usually used in the processes of the prior art.

Description

- ~ lZ528 ~

The invention relates to a method for the production of propylene accompanies the formation of butenes, in much less proportion important, by the transformation of methanol and / or dimethylether into presence of certain aluminosilicates.

The transformation of methanol into hydrocarbons constitutes a remarkable reaction, long known, during which there is formation of carbon carbon bonds from the "radicals" in Cl which are formed from methanol in the presence of certain catat--acid lysers. ~ this transformation has not taken on an undue importance trielle as from the 1970s and this because of two events:

. discovery, of sufficiently active catalysts, and above all selective, capable of transforming methanol into hydrocarbons, and in particular in auto petrol.

. and the policy of oil producing countries leading to disruption of economic and technical data in the petroleum and petrochemical industries.
.
Most of the world's methano production ~
comes from natural gas, but we also get it from hydrocarbon . . .
:.,,:, ..:. . : ~

.. '~,'. ~.

- 12 ~ Z8 ~) ~

heavier bures, after adequate transformation, by fermentation ~
by distillation of wood, etc., and also from charcoal, or any another material rich in carbon derivatives.

With their new technique for transforming methanol into hydrocarbons, Mobil has introduced other sources of synthetic fuels ~ in addition to those of conventional processes:
Fischer-Tropsch and Bergius.

Economically, obtaining hydrocarbons from methanol seems to be more competitive than other existing techniques synthesis of fuel from coal.

With an appropriate choice of catalyst and an adequate adjustment operating conditions, it is possible to orient the transformation methanol to obtain light or heavier hydrocarbons, to obtaining aromatics or olefins.

The present invention relates more particularly to a method of manufacture of propylene ~ from methanol or dimethyl ether or their mixture, process presenting a certain interest in the economic context current.
Indeed propylene constitutes one of the oldest products of base of the chemical and petrochemical industry, occupying a very important place aunt among light olefins.
It is widely used in the preparation of alkylates and essences of polymerization to improve the octane number of fuels.
It is also used in very large quantities in the ~ 5 prepsration of plastics such as polypropylene and also in the preparation of other products such as:
acrylonitrile, propylene oxide, propanol, cumene etc.

Until now propylene was mainly obtained as under petroleum refinery product and mainly steamed cracker . . .

, ~
.: ~. :
.

:
: ~. .
. . . .

--` lZ5; ~

naphthas.

But the oil economic situation made that we Orient towards the steam cracking of heavier products, by abandoning that of "naphtha" cuts which leads to a decrease in the production of propylene.

It is therefore interesting to consider obtaining this product S by another route, hence the interest of the present process.

There are many works relating to the transformation of methanol to hydrocarbons, transformation which takes place in the presence of ~;
catalysts.

The most used catalysts are or contain zeolites which are crystallized aluminosilicates and seem to perfectly suitable for this type of transformation:

- due to their acidic properties - and because of their structure by ~ defined definition, the dimensions of their intercrystalline canals being of the same order of magnitude as the - dimensions of organic molecules staying there during the reactio ~.

IS The major drawback that arises in this reaction of transformation of methanol into hydrocarbons is the rapid deactivation of catalyst caused by irreversible deposits of organic products very condensed nicks t "coke'i). ' Many works have been found in the literature who are trying to give a solution to this problem. They seek to modify, by various means, the catalytic properties of these aluminum silicates trying to give them greater selectivity and consequently to reduce the formation of "coke" on their surface.

~ I

"':':.

- ~ 2S2l3 ~) 1 - 3a -The object of the present invention is a pro-assigned to manufacture olefins containing 2 to 5 atoms of carbon per molecule, from a reagent which is methanol or dimethyl ether or a mixture thereof, killed in the presence of at least one mor-dealuminized denite having a higher Si / Al atomic ratio less than 80, an Na20 content of less than 0.1% by weight, a specific surface, after shaping, between 390 and 600m2 / g, a total pore volume of between 0.540 and 0.650 cm 3 / g, a pore volume, for pores of diameter be greater than lOnm (10 x lO 9m) between 0.350 and 0.550cm3 / g, and carried out by passing the reagent di-read by a carrier gas or by steam, the centering said reagent in the carrier gas or the vapor of water, entering the reaction zone, being included between 5 and 75% by volume, the hourly volume flow (LSVH) being between 0.5 and 100 liters of reagent liquid per liter of catalyst per hour, the temperature ture being between 300 and 650C and the pressure between 0.1 and 3 MPa, the method being characterized in that, after having separated the olefins from the reagent and diluent from the reagent tif (gas or water vapor), the olefins are fractionated fa ~ on to collect on the one hand a cup containing essen-tally hydrocarbons with 2 and 3 carbon atoms per molecule, and on the other hand a section containing ma-part of the upper olefins containing at least 4 carbon atoms per molecule, this last cut ~ both recycled at least in part in the reaction zone '~.
.
. . '. . . .

~ 2S ~ 8 ~ 1 uses a catalyst optimized for the production of light olefins which is described in the European Patent n 0084 748 of January 4, 19 ~ 2.

In the patent, it is used for the production of hydrocarbons unsaturated having essentially 2 to 5 carbon atoms per molecule, a catalyst based on zeolite modified so as to increase very considerably its lifetime and selectivity.

This modification consists in de-aluminizing a zeolite of the type synthetic mordenite.

So that this modified zeolite exhibits good selectivity in the production of olefins, the Si / Al ratio (in atoms) is between 80 and 150. However, we have found that by operating in certain operating conditions, which is the subject of this patent, we could significantly improve propylene yields got.
: `? '' According to the invention, the best yields of olefins having

2 to 5 and preferably 3 to 4 carbon atoms per molecule ~ are obtained by reacting, in the presence of a dealuminated zeolite, methanol and / or dimethyl ether, at a suf ~ isante temperature, and diluting suffi-the reagent with at least tm gas (nitrogen, hydrogen, monoxide of carbon, carbon dioxide) or water vapor.

In practice, the reagent is reacted (methanol and / or dimer-thylether ~ diluted ~ by a carrier gas or water vapor on at least one dealuminated mordenite type catalyst, at a pressure between O, I and 3 MPa, and preferably between 0.01 and 0.5 MPa ~ and at a :
temperature between 300C and 650C, and preferably between 350C and 550C.

~ 2S28 ~

The concentration of reagent in the gas (or the water vapor) entering the catalytic bed will be taken between 5 and 75 ~ in volume, and preferably between 25 and 60 ~.
Hourly volumetric flow (LSVH) will be understood between 0.5 and 100 liters ~ of liquid methanol per liter of catalyst per hour, and preferably between 0.5 and 50 liters.
The products leaving the reaction zone are directed to a separation zone where the oleans are separated fines obtained from the reagent (methanol and / or dimethyl ether) which has not reacted, and which is recycled at least in part, and reagent diluent (s) (gas or water vapor) which can also be recycled. The hydrocarbons obtained are then subjected to separation in order to recover from a share a cut rich in olefinic hydrocarbons at 2 and

3 carbon atoms per molecule (preferably a major part of propylene? and on the other hand a cup containing mostly higher olefins, having at least

4 carbon atoms per molecule, this cut containing also generally butanes.
It has been observed, which constitutes the ob] and of the present invention, that if we sent a part at least of this upper olefin cut towards the tr ~ e of the reactor where it comes into contact with the catalytic bed lytic together with methanol and / or dimethyl-ther, we got two advantages:
. on the one hand we eliminate part of the calories produced by the reaction and . on the other hand, we significantly increase the return propylene and the service life of the catalyst.
Preferably, 20 to 60% by weight will be recycled of this cut of upper olefins. Although the examples ples presented, and which illustrates the present invention, . . ~ -. .
:

".;'' ~ '''~
''',' . . ',, '' S280 ~ 1 - 5a -be made on a single fixed bed, consider that this technique is not limiting.
In fact, the catalyst can also be placed in two or more successive beds, arranged in one or in several reactors. This provision having the advantage to allow better evacuation of calories te ~ r ~ ~ 5'i ~ -- - - ---- - _ _ _ _ '''''','-'''', ~

`; . :, - ' o ~

Catalysts can also be used in bed mobile can be contained in one or more bed reactors mobile, this technique making it easier to eliminate the exothermicity of the reaction and also increase the speed reaction of lfs-reactors with improved selectivity: the charge circulates successively in each reactor or zone of reaction following an axial or radial flow (radial meaning a flow from the center to the periphery or from the periphery to the center). The reaction zones are arranged in series, for example side by side or superimposed. The charge flows successively through each of these reaction zones, with introduction of charge or of a intermediate recycling between reaction zones in order to control the thermal level of the reaction by adding or removing calories; fresh catalyst is introduced at the top of the first zone reaction where the fresh charge is introduced; it then flows gradually from top to bottom of this area from which it is drawn progress-from the bottom, and by any appropriate means (lift in particular in the case of reactors arranged side by side) it is transports to the top of the next reaction zone in which it also gradually flows from top to bottom, and so on up to the last reaction zone below which the catalyst is also gradually withdrawn and then sent to a rege zone neration. At the exit of the regeneration zone, the catalyst is gradually reintroduced at the top of the first reaction zone.
The various catalyst withdrawals are carried out as indicated below.
above "gradually" that is to say either periodic ~ ent or conti-bare. Continuous withdrawals are preferred to periodic withdrawals.

The catalyst used in the present invention, catalyst whose preparation and performance have been described in the patent Europ ~ in N 0084748 is based on dealuminized mordenite having an Si / Al (atomic) ratio greater than 80, preferably between 80 and 95, more particularly between 87 and 90, an Na20 content of less than 0.1% by weight, a specific surface, after shaping with the addition possibly around 5 to 40%, for example 10 ~, by weight of a clay binder, between 390 and 600 m / g, and preferably between 420 and j5om2 / g a total pore volume of between 0.540 and 0.650 cm / g, and preferably between 0.550 and n, 600 cm3 / g; a pore volume, for pores of diameter ~ up to ~.

'~'. .
- '~ ~',, '::

'' ~ 2 ~

(10 X lo ~ 9m) lO nm / ~ between 0.350 cm / g and 0.550 cm3 / g and preferably between between 0.400 and 0.500 cm3 / g, and preferably a bed density for pellets of approximately 3 x ~ 2mm, between 0.600 and 0.700.

The examples which follow and which illustrate the present invention were made with a catalyst based on dealuminized mordenite and tablet (3 x 2 mm) having the following characteristics Area .......... O ............................ 450 m2 / g Total pore volume ...................... 595 cm3 / g Porous volume for pores> lOnm ..... 0.460 cm3 / g 10 Bed density (packed) .................. 0.650 g / cm (for 3 x 2mm beads) Si / Al ratio (atom) .................... 89.2 The charge used was a 50/50 mixture by weight of water and methanol. The reaction was carried out in a pilot unit having a reaction vertical upright containing 40 cm3 (~ 6 g) of the pelletized catalyst (3 x 2 mm) containing 10% clay binder (specific surface of the cataly-tick 455 m / g) The catalyst was brought to a temperature of 500C under a flow rate of air of 250 l / h, and previously dried by pa ~ passage ~ through a bed of light, for 2 hours.

After this pretreatment, we therefore pass through the catalytic bed.
lytic 50/50 by weight of methanol-water vapor.

The operating conditions which are the same in all the examples which follow / were:;

Atmospheric pressure Temperature ........... 460 ~ C
LHSV ............. f .... I h We consider the test as finished when the sum of the olefins in C2, C3, C4 produced becomes less than 10% by weight of the yield initial. This time is after approximately 50 hours.

. ~

: -:

- ~ 5 ~ 8 ~ 1 E ~ EXAMPLES
In these examples, all of the unconverted methanol was recycled.
and all of the water vapor used.

Example 1 This test was conducted 50 hours 50US the conditions indicated above, without recycling of C ~ 4 hydrocarbons (load: 50 ~ weight of water, 50% by weight of methanol).

Example 2 It was also carried out under the same operating conditions, as in Example 1 but with a recycling of part of the hydrocarbons into C 4 obtained.

The composition of the load was therefore here, with recycling understood, the following:

Water ........................ 50% by weight Methanol ................. 42.5% by weight Recycling C4 ............. 7.5% by weight.

At the outlet of the reactor and after separatior of steam and alcohol not having reacted, the hydrocarbon effluent is sent to an area of distillation OUon separates, by the bottom of the column, the hydrocarbons into .... ~ t C4, which represent 12.51% by weight of the total incoming charge in the reaction zone (water, alcohol and hydrocarbons) and having by weight the following composition:

Butanes .......................... 15.10 Butenes .......................... 63.15 ~ C5 ------------ -.-...................... 18.15 Aromatics ....................... 3, O0 .

, ~ 2S28 ~

At the head of the æone of ~ ractioning ~ we support the hydrocarbons resen Cl, C2 and C3 containing more than 90% by weight of propylene.
The composition by weight of this cut very rich in propylene being the next :

Methane .............. 1.28%
Ethane ..... O ......... 0.16%
EthyleneA ~ 5.13%
Propane .... ~ ......... 1.20%
Propylene ........... 92.23%
lOO, OO%

The cut containing the C 4 hydrocarbons represents 12.51%
by weight of all the products entering the reaction zone, 59.95% by weight of this cut is sent for recycling to the ~ one reaction, this recycled ~ e constituting 7.5 ~ by weight of the total charge arriving in this area.

The rest of this cut (40.05 7) is sent, for example, towards the petrol pool.

``

~ 2S- ~ 8 (~

In the following table we present the overweight composition of the products obtained in examples 1 and 2 with respect to the filler (after 50 hours of treatment).
.

Products Products _ Methanol 2.73 2.34 Dimethylether 0.19 0.16 Water 76.50 72.52 Hydrocarbons Cl at 0.33 0.33 Ethylene 0.66 0.64 Propylene ~ 11.50 C ~ + 7.50 12.51 From the results obtained and presented in the table above, it can be seen that by operating under the conditions of Example 1, that is to say, without recycling the C4 hydrocarbons obtained, a 25.57 kg propylene production per 100 kg of methanol transformed, while if we operate by recycling the so-called hydrocarbon cut we obtain 28.63 kg of propylene per 100 kg of methanol tran6for ~ e.

, '~
.

-` ':

:. . .., -:

Claims (7)

The embodiments of the invention, concerning the-which an exclusive property right or privilege is claimed, are defined as follows: 1. Process for the manufacture of olefins containing 2 to 5 carbon atoms per molecule, starting from a reac-tif which is methanol or dimethyl ether or their met-diaper, carried out in the presence of at least one catalyst dealuminized mordenite base having an atomic ratio Si / Al greater than 80, an Na2O content less than 0.1% by weight, a specific surface, after shaping me, between 390 and 600m2 / g, a total pore volume between 0.540 and 0.650cm3 / g, a pore volume, for pores with a diameter greater than 10nm (10 X 10-9m) com-taken between 0.350 and 0.550cm3 / g, and carried out by pass the diluted reagent through a carrier gas or through water vapor, the concentration of said reagent in the gas carrier or water vapor, entering the reaction zone tion, being between 5 and 75% by volume, the flow hourly volumetric (LSVH) being between 0.5 and 100 liters of liquid reagent per liter of catalyst and per hour, the temperature being between 300 and 650 ° C and the pressure between 0.1 and 3 MPa, the process being characterized in that, after having separated the ole-reagent fines and reagent diluent (gas or vapor of water), the olefins are fractionated so as to collect on the one hand, a section essentially containing hydro-carbides with 2 and 3 carbon atoms per molecule, and more be part of a cut containing mainly olé
higher fines containing at least 4 carbon atoms per molecule, this last cut being recycled at least partly in the reaction zone. 2. Method according to claim 1, characterized in that we add, by weight, 5 to 40% of an ar-gileux with dealuminated mordenite. 3. Method according to claim 1, characterized in that the Si / Al atomic ratio of mordenite desa-illuminated is between 80 and 95. 4. Method according to claim 3, characterized in that the pore volume for diameter pores greater than 10nm, is between 0.400 and 0.500cm3 / g. 5. Method according to claim 1, 2 or 3, characterized in that 20 to 60% by weight of the section mainly containing higher olefins laughing. 6. Method according to claim 1, characterized in that we collect a cup containing in major part of propylene. 7. Method according to claim 1, characterized in that at least part of the reactant is recycled reacted (methanol or dimethyl ether) and partly at least the gas or water vapor that was used to dilute the reagent.