Catalyst, method of its preparation and method for producing olefins from paraffins monohalogenated

 

(57) Abstract:

The catalyst receiving Alifanov of monohalogenated paraffins comprises magnesium chloride on the carrier - filamentous carbon, which is produced by decomposition of hydrocarbons on metals of the iron subgroup or grade material Sibunit. Also, a method for preparation of the catalyst according to the present invention by impregnation of the carrier with a solution of magnesium chloride with a concentration of from 0.05 to 3.4 mol/L. the invention solves the problem of creating a stable catalyst dehydrohalogenating monohalogenated paraffins and the problem of increasing the yield of olefins by increasing the selectivity of the process and the degree of conversion monohalogenated paraffins. 3 s and 5 C. p. F.-ly, 1 table.

The invention relates to catalytic chemistry, in particular to catalysts for the synthesis of olefins from monohalogenated paraffins, and may find application in the disposal of chlorinated organic wastes, as well as in the production of synthetic rubber.

The reaction dehydrohalogenating monohalogenated paraffins (RX), which are formed olefins and the corresponding hydrogen halides, catalyzed by various salts: chlorite is fishing, zeolites with different exchangeable cations [Noller H., Kladnig W. Elimination reaction over polar catalysts. Mechanistic considerations. - Catal. Rev. - sci. eng., 1976, v.l3, N2, p.149-207]. However, most of these catalysts during the reaction is deactivated. Among oxide catalysts are most commonly used oxides of metals of the 2nd and 3rd groups of the periodic system or a binary oxide system [Beranek L., Kraus M. Heterogeneous elimination, addition and substitution. - in book Comprehensive chemical kinetics/ ed. by Bamford, C. H., Tipper, C. F. H., Elsevier, Amsterdam, 1978, v.20, p.263-398]. The activity and selectivity of oxides in the reaction is largely determined by the strength of interaction of the coordinatively unsaturated atoms and functional groups on the oxide surface with a molecule RX. In this regard, the most interesting are the oxides of alkaline earth metals and aluminum oxide.

The process of dehydrohalogenation at comparatively low temperatures (50-100o(C) does not allow to achieve an acceptable degree of conversion RX. This is due to thermodynamics of the reaction off halogenated NC, according to which a significant degree of conversion of RX can be achieved by conducting the reaction at 200oC and above. It should be noted that for different Halogens X and various isomers RX thermodynamics RX (1-chlorobutane) compared to tertiary (tertbutylphenyl) is converted into olefins is much more difficult. From the literature it is known that the reaction of removal of HX-oxide catalyzed by Protic centers, and the catalytic activity depends on the strength and concentration of acid sites on the catalyst surface. However, the presence of a very strong proton and aprotic centers undesirable impact on the selectivity of the process of dehydrohalogenation.

As example can serve as aluminum oxide, having a high activity in the reaction of dehydrohalogenating RX at temperatures of 200-400oC. Suspension of catalyst-Al2O3(SID=200 m2/g) 0.5 g is made red-hot in a stream of dry air for 30 minutes Then the temperature is reduced to 250oWith and on the catalyst serves pairs 1-chlorobutane (concentration 1-chlorobutane nitrogen is 7.5%). The initial reaction rate W=0.11 mol/g h For three hours experience the activity of the catalyst is reduced by approximately 4 times. The products of the reaction - mixture of isomers of butylene (including isobutylene). The degree of conversion of 1-chlorobutane not reported [A. Heinzelmann, R. Letterer, and H. Noller Elimination reactions over polar catalysts. Monatsch. Chem., 102, 1971, p.1750].

However, in the acidic centers of Al2ABOUT3at these temperatures, there is leakage of various side the activity of the catalyst for olefins.

The oxides MgO and Cao exhibit higher selectivity to olefins, because on the surface there is no such marked acid sites. However, the activity of these catalysts in the process of dehydrohalogenating significantly inferior to the activity of Al2ABOUT3. One way to increase the specific catalytic activity of MgO and Cao is the increase of the specific surface oxides that can be achieved using aerogel technique of preparation with the subsequent removal of solvent in supercritical conditions [Koper O. B., Lagadic J., Volodin A. M., and K. J. Klabunde Alkaline-earth oxide nanoparticles obtained by aerogel methods. Characterization and rational for unexpectedly high surface chamical reactivities. Chem. Mater. 1997, 9(11), p.2468-2480]. The use of aerogel technology allows to obtain the oxides MgO and Cao with a specific surface area of 400 m2/g [K. J. Klabunde, J. Stark, O. Koper, C. Mohs, Park, D. G. , Decker, S., Jiang Y., I. Lagadic, and Zhang D. Nanocrystals as stoichiometric reagents with unique surface chemistry. J. Phys. Chem. 1996, v.100, p.12142-12153].

However Aerolinie samples of the oxides MgO and Cao are unstable in the process of dehydrohalogenating RX: due to its high dispersion of nanosized oxides already at 100-150oTo interact with halogenation NC, formed during the reaction. As a result, for example, ultrafine the specific surface area of more than an order of magnitude. The authors found that education during topochemical reaction phase MgX2causes a significant increase in catalytic activity of the sample while the selectivity to olefins, close to 100%.

Closest to the present invention are the catalyst and the process of obtaining 2,3-dimethylbutene of 1-chloro-3,3-Dimethylbutane (EP 372183 AND 13.06.1990). The catalyst contains magnesium chloride, deposited on activated carbon. However, the catalyst has insufficient thermal stability.

The present invention solves the problem of creating a stable catalyst dehydrohalogenating monohalogenated paraffins and the problem of increasing the yield of olefins by increasing the selectivity of the process and the degree of conversion monohalogenated paraffins.

As the active component for the new catalyst dehydrohalogenating selected magnesium chloride MgCl2deposited on a carbon carrier in an amount of not less than 0.2 wt.%. Calcium chloride, despite the higher activity compared with MgCl2not been used by us due to the high hygroscopicity (deliquesces in the air), which creates a significant inconvenience when using it in Kacha is icewall to the effects of HX;

2) minimal impact on the selectivity of the process;

3) thermal stability.

Carbon carriers meet all the following requirements. In the present invention using carbon carriers of different brands: Sibunit) porous carbon material [RF Patent 1706690, From 01 To 31/10, 1992] and filamentous carbon. Filamentous carbon is a product of catalytic decomposition of hydrocarbons on metals of the iron subgroup (Ni, Co and Fe) and is a tangle of graphite filaments with a diameter of 200-500 angstroms and a length up to several microns [Century. Century. Chesnokov, R. A. Buyanov. The formation of carbon filaments with catalytic razlozheniye hydrocarbons on metals of the iron subgroup and their alloys. USP, 2000, 69 so. vol.7. S. 675-692].

The task is also solved by a method of preparation of the catalyst for olefin production monohalogenated paraffins, according to which magnesium chloride is applied on the carbon carrier by impregnation of the latter with a solution of magnesium chloride with a concentration of from 0.05 to 3.4 mol/l, to content in the media is not less than 0.2 wt.%. As a carbon carrier used filamentous carbon, obtained by the decomposition of hydrocarbons on metals of the iron subgroup, Il is the temperature value 400-600oC.

The task is also solved by a method of producing olefins from monohalogenated paraffins in the presence of the above catalyst consisting of magnesium chloride, at a temperature of 200-400oC. as monohalogenated paraffin using 1-chlorobutane and or 1-rambutan, and/or 1-iodobutane, concentration monohalogenated paraffin in argon is not less than 4 vol.%.

Examples 1-3 are shown for comparison.

Example 1. Filamentous carbon as a catalyst in the amount of 0.3 g load in a flow reactor with weights Mac-Bains heat for 20-25 minutes in an argon flow of 20 l/h to a temperature of 500oC. After calcination in a stream of argon at a temperature of 500oC for 1 h, lower the temperature in the reactor to 350oC. Then the argon 2 l/h start to pass through a bubbler filled with 1-chlorobutane, and spend the hydrodechlorination reaction at a temperature of 350oC for 5 h

The concentration of 1-chlorobutane in argon 15% vol.

The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 2.5%.

Over time (after 5 h) is reduced to 2.2%.

The catalytic activity of the th reactor with weights Mac-Bains heat for 20-25 minutes in an argon flow of 20 l/h to a temperature of 500oC. After calcination in a stream of argon at a temperature of 500oC for 1 h, lower the temperature in the reactor to 350oC. Then the argon 2 l/h start to pass through a bubbler filled with 1-chlorobutane, and spend the reaction dehydrochlorinating at a temperature of 350oC for 5 h

The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 14%.

Over time (after 5 h) is reduced to 13.1%.

Catalytic activity: 3.1 mmol/g h

Example 3. Similar to examples 1 and 2, characterized in that the catalyst is used reactive magnesium oxide obtained by burning magnesium wire in a stream of oxygen (SID=102/g). In the reaction under the action of hydrogen chloride is a partial transition of magnesium oxide to magnesium chloride. The latter is characterized by a greater catalytic activity, which leads to an increase in the degree of conversion of 1-chlorobutane.

The reaction products: butylene, hydrogen chloride, magnesium chloride.

Initial degree of conversion of 1-chlorobutane is 14.4%.

After 4 h increases ASS="ptx2">

Catalytic activity (after 5 h): 12.9 mmol/g h

Examples 4-14 illustrate the invention.

Example 4. The catalyst comprising 0.2 wt.% MgCl2and for 99.8 wt.% filamentous carbon, obtained by impregnation of the granules of the carrier with a solution of magnesium chloride, followed by drying, in the amount of 0.4 g load in a flow reactor with weights Mac-Bains heat for 20-25 minutes in an argon flow of 20 l/h to a temperature of 500oC. After calcination in a stream of argon at a temperature of 500oC for 1 h, lower the temperature in the reactor to 350oC. Then the argon 2 l/h start to pass through a bubbler filled with 1-chlorobutane, and spend the reaction dehydrochlorinating at a temperature of 350oC for 5 h

The concentration of 1-chlorobutane in argon 15% vol.

The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 29.3 per cent.

Over time (after 5 h) is reduced to 29.1 percent.

Catalytic activity: 6.9 mmol/g h

Example 5. Similar to example 4, the only difference being the composition of the catalyst of 1.8 wt.% MgCl2and 98.2 wt.% filamentous carbon, grain size of the grains of the medium are the same.

The concentration of the stop 1-chlorobutane is 66,8%.

Over time (after 5 h) is reduced to 64.4 per cent.

Catalytic activity: 15.7 mmol/g h

Example 6. Similar to example 4, the only difference being the composition of the catalyst of 3.5 wt.% MgCl2and 96.5 wt.% filamentous carbon, grain size of the grains of the medium are the same.

The concentration of 1-chlorobutane in argon about 15. %. The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 78,1%.

Over time (after 5 h) is reduced to 78%.

Catalytic activity: 19.2 mmol/g h

Example 7. Similar to example 4, the only difference being the composition of the catalyst of 8.1 wt.% MgCl2and 91,9 wt.% filamentous carbon, grain size of the grains of the medium are the same.

The concentration of 1-chlorobutane in argon 15% vol.

The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 77.2 percent.

Over time (after 5 h) is reduced to 77%.

Catalytic activity: to 18.7 mmol/g h

Example 8. Similar to example 4, the only difference being the composition of the catalyst of 14.5 wt.% MgCl2and 85.5 wt.% filamentous carbon, grain size of the grains of the medium are the same.

The concentration of 1-chlorobutane the butane accounts for 71.4%.

Over time (after 5 h) is reduced to 71.2 percent.

Catalytic activity: 16,6 mmol/g h

Example 9. Analogous to example 5, the only difference being the temperature of the reaction dehydrochlorinating 200oC.

The concentration of 1-chlorobutane in argon about 15. %.

The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 33.8 percent.

Over time (after 5 h) is reduced to 33.5%. Catalytic activity: 8,2 mmol/g h

Example 10. Analogous to example 5, the only difference being the temperature of the reaction dehydrochlorinating 400oC. compared to the temperature of 350oWith the degree of transformation of 1-chlorobutane slightly higher, but the gain in catalytic activity comparable with the energy costs. The concentration of 1-chlorobutane in argon about 15. %.

The reaction products: butylene and hydrogen chloride.

The degree of transformation of 1-chlorobutane is 80,3%.

Over time (after 5 h) decreases up to 80.1%.

Catalytic activity: 19,7 mmol/g h

Example 11. Similar to example 6, characterized in that as the carrier uses carbon grade material Sibunit-2A (SBET- 406 m2/Nita and filamentous carbon is approximately the same.

The concentration of 1-chlorobutane in argon 15% vol.

The reaction products: butylene and hydrogen chloride.

The weight of the sample catalyst for two hours of reaction increased by 12% and then for the experience did not change.

The degree of transformation of 1-chlorobutane in the first hour is 75,0% and for the next 2 hours and decreased to 69.8% and then remains stable.

Catalytic activity: 17.3 mmol/g h

Example 12. Similar to example 6, characterized in that instead of 1-chlorobutane used 1-rambutan. In the reaction allocated NVG, under which the magnesium chloride passes into bromide of magnesium. The resulting bromide magnesium less active in the reaction of dehydrohalogenating than the original chloride, so over time there is some reduction in the degree of conversion.

The concentration of 1-bromobutane in argon 7% vol.

The reaction products: butylene, bromovalerate and magnesium bromide.

The degree of transformation of 1-bromobutane is 83%.

Over time (after 5 h) is reduced to 79,2%.

The degree of conversion of magnesium chloride to bromide (5 h) 81%.

Catalytic activity (after 5 h): 19,1 mmol/g h

Example 13. Similar to the previous 1-bromobutane in argon 7% vol.

The reaction products: butylene, bromovalerate and magnesium bromide.

The degree of transformation of 1-bromobutane is 18.8%.

Over time (after 5 h) is reduced to 14.9%.

The degree of conversion of magnesium chloride to bromide (5 h) 68.5 per cent.

Catalytic activity (after 5 h): 3.6 mmol/g h

Thus, when the concentration of MgCl2< 0.2 wt.% the product will be small, at a concentration of MgCl2> of 14.5 wt.% the yield starts to noticeably drop. The optimal range of concentrations applied MgCl2which provides the highest yield of reaction product is approximately 1.5-9 wt. %. At the reaction temperature T<200With the release of butylenes is sharply reduced; when the temperature increases from 350oWith up to 400oWith and above the degree of conversion increases very slightly, that does not justify expenditure of energy. The optimal temperature range for the reaction: 300-400oC, preferably T=350oC.

As can be seen from the description of examples and data tables, the present invention allows to synthesize olefins from monohalogenated paraffins and may find application in the utilization of chlorine-containing waste, and prom is paraffin, incorporating magnesium chloride on a carrier, characterized in that as the media it contains filamentous carbon, obtained by the decomposition of hydrocarbons on metals of the iron subgroup, or grade material Sibunit.

2. The catalyst p. 1, characterized in that it contains magnesium chloride in an amount of not less than 0.2 wt. %.

3. The preparation method of the catalyst for olefin production monohalogenated paraffins, incorporating magnesium chloride on the carrier by impregnation of the latter with a solution of chloride of magnesium, wherein the magnesium chloride with a concentration of from 0.05 to 3.4 mol/l applied to filamentous carbon, obtained by the decomposition of hydrocarbons on metals of the iron subgroup or grade material Sibunit.

4. The method according to p. 3, characterized in that the applied magnesium chloride to content in the media is not less than 0.2 wt. %.

5. The method according to p. 3, characterized in that after impregnation the catalyst is dried and then calcined in a stream of inert gas at a temperature of 400-600oC.

6. The method of producing olefins from monohalogenated paraffins in the presence of a catalyst consisting of magnesium chloride on the carrier, at elevated temperatures by p. 6, wherein the process is carried out at a temperature of 200-400oC.

8. The method according to PP. 6 and 7, characterized in that as monohalogenated paraffin using 1-chlorobutane, and/or 1-rambutan, and/or 1-idbutton.

9. The method according to PP. 6-8, characterized in that the concentration monohalogenated paraffin in argon is at least about 4. %.

 

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