Method of producing isoprene

FIELD: chemistry.

SUBSTANCE: invention relates to a method for liquid-phase synthesis of isoprene by reacting formaldehyde with isobutylene or derivatives thereof in the presence of a solid-phase catalyst and subsequent extraction of the end product, characterised by that the catalyst used is phosphates selected from zirconium, niobium or tantalum phosphates, wherein the reaction takes place at temperature 100-200°C, pressure 7-20 atm and molar ratio of isobutylene or derivative thereof to formaldehyde equal to (1-20)/1.

EFFECT: use of the method enables synthesis of isoprene with high output and selectivity.

7 cl, 17 ex, 1 tbl

 

The present invention relates to a liquid-phase process for the preparation of isoprene, in particular the production of isoprene by the interaction of formaldehyde with derivatives of isobutylene with a heterogeneous catalyst.

In industry, there are various ways of obtaining isoprene: 1) from isobutylene and formaldehyde, 2) a two-step dehydrogenation of isopentane, 3) dehydration of isoamylenes, 4) dimerization of propylene, 5) extraction of isoprene from C5 fraction of the pyrolysis of petroleum products, among which the most attractive is the obtaining of isoprene by condensation of isobutylene with formaldehyde in connection with the fact that both of these reagent made on the basis of the primary products of oil and associated gas.

Known methods based on gas-phase process for the production of isoprene in the presence of different heterogeneous catalysts, for example GB 863330; GB 841746; GB 1025432; US 4014952; US 4000209; US 3437711; US 3662016; US 4092372. As catalysts in these processes use phosphoric acid supported on silica gel, phosphates elements, IIIB group (boron, aluminum, gallium) supported on silica gel, phosphates, chromium, cobalt, calcium, barium, copper supported on silica gel, acid catalysts based on tin oxide and silica or silica and bismuth also use the silver deposited on the silicate.

However, the local methods do not fully satisfy the essential requirements for industrial catalysts. Some methods use catalysts that give low conversion or a large number of unwanted side products. Another part of the method allows to achieve a high degree of conversion, however, the used catalysts are rapidly deactivated and have a small mainegenealogy mileage. In addition, the major drawbacks of single-stage gas-phase methods for producing isoprene are the high energy costs associated with the high temperature process, the need for separation and recycling of large quantities of isobutylene, and the need for concentration of formaldehyde due to incomplete conversion.

These drawbacks liquid-phase methods for producing isoprene. Most of these methods involve a two-step synthesis of isoprene, in which the first stage of the process at a temperature of about 100°C. and a pressure of 20 at from isobutylene and formaldehyde in the presence of sulfuric or phosphoric acid formed as a by - product of 4,4-dimethyldioxanes-1,3 (DMD). In the second stage DMD decompose in the gas phase by heterogeneous phosphate catalyst at temperatures from 370 to 400°C. the Drawbacks of such methods are the two-phase process, the use of soluble acid, the presence of which in the system leads to rapid corrosion, formation of large amounts of high-boiling pobo the different products, and rapid deactivation of the catalyst decomposition DMD.

Known methods for producing isoprene, aimed at creating a closed system of circulation of acid (SU 460614, EN 2098398, JP 60-226834), the translation process of the DMD decomposition in the liquid phase (RU 2098398, EN 2085552, JP 60-224641, JP 60-226834, JP 58-116428), for processing high-boiling by-products (WFP) in isoprene (EN 2134679, EN 2135450, EN 2164909), on the search for new additives used in the synthesis of isoprene (JP 60-224641, JP 58-116428), and the use of weaker acids as catalyst (SU 508050, SU 889653, SU 1743136, SU 1743137).

Known single-stage method for the production of isoprene, involving the use of metal chlorides as catalysts (US 3890404).

Also known single-stage method comprising the balance shift by removal of isoprene from the reaction zone (US 4511751). All this leads to an increase in the selectivity of the process, reducing energy intensity of the process and reducing acids.

However, the known methods do not solve the problems associated with corrosion of the equipment, waste formation by neutralizing acids and the formation of high-boiling by-products in the synthesis of isoprene.

The closest in technical essence and the achieved result is a method of producing isoprene comprising the interaction of formaldehyde with a derivative of isobutylene in the presence of as is utilizator ion-exchange resin (JP 59-025337, 1984).

The disadvantage of this method is to add water-soluble acid catalyst and implementation process in two temperature zones and, accordingly, the use of two reactors.

The present invention is to develop a liquid-phase method devoid of the above disadvantages and which allows to synthesize isoprene with high yield in the conditions of the liquid phase.

The problem is solved is described by way of liquid-phase production of isoprene by the interaction of formaldehyde with isobutylene or its derivatives in the presence of a solid catalyst and subsequent selection of the target product, wherein the catalyst used phosphate selected from phosphates of zirconium, niobium or tantalum, and the interaction is carried out at 100-200°C., a pressure of 7 to 20 MPa, and a molar ratio of isobutylene or isobutylene derived to formaldehyde equal to (1-20)/1.

Preferably, as isobutylene derived using tributyl alcohol, methyl tertiary butyl ether, ethylcelluloses ether or mixtures thereof.

Preferably, after the interaction of formaldehyde with isobutylene or its derivatives formed by-products are separated from the target product and recycle in the head in the process.

It is also possible after vzaimode istia formaldehyde with isobutylene or its derivative and separating the resulting products to carry out the decomposition of the latter on solid-phase catalyst, containing phosphates of zirconium, niobium or tantalum.

By-products of the interaction of formaldehyde with isobutylene or its derivatives primarily represent 4,4-dimethyldioxanes-1,3, methyldihydromorphine, 3-methylbutanol-1,3 or a mixture of the above substances with isobutylene or its derivatives.

As a catalyst, you can use the phosphates of zirconium, niobium or tantalum, is deposited on an inorganic carrier.

Preferably, the process is carried out in continuous flow reactor with a fixed catalyst bed.

The possibility of achieving the stated technical result due to the choice of the claimed catalysts previously used in such processes, and selection conditions of the method.

The proposed method in General form as follows. Pre make the preparation of a catalyst by heating in a current of inert gas (nitrogen, helium) at 150°C for 1 hour. Formalin with isobutylene or derivatives of isobutylene (tertbutanol, methyl tertiary butyl ether, ethylcelluloses ether) served in a flow type reactor with a fixed catalyst bed. The pressure regulator at the outlet of the reactor to give the necessary pressure. At the exit of the reactor products condense in the absorption of cold acetonitrile. Products anal is serout using gas chromatography. The amount of formaldehyde determine the sulfite titration method with hydrochloric acid.

The following specific examples illustrate the implementation of the invention using various claimed catalysts at the stated conditions of interaction and demonstrate the achievement of the technical result. The results and parameters of the method are summarized in table.

Example 1.

1 g of the niobium phosphate (NbOPO4) are placed in a flow reactor, rinsed with nitrogen at a temperature of 150°C for 1 hour, then serve with formalin speed of 0.43 g/h (formaldehyde 36%) and tertbutanol with the speed of 1.55 g/h at a ratio of 1:4 and at a pressure of 15 ATM. The reaction is carried out for 3 hours. At the exit of the reactor discovered the following main products: tertbutanol 0,236 g/h, isobutylene 0,77 g/h, resulting from the dehydration part of tertbutanol, isoprene of € 0.195 g/h, methyldihydromorphine (MDGP) to 0.055 g/h, 4,4-dimethyldioxanes-1,3 (DMD) 0.008 g/h, WITH 0.008 g/H. the Obtained results correspond to the yield of isoprene on turned formaldehyde 55% conversion of formaldehyde to 100%. The yield of isoprene in the transformed derivatives of isobutylene (TBS and isobutylene) is 72%. The results of the experiment are presented in the table.

Example 2.

The process is conducted as in example 1, the difference lies in the fact that the measurement is the process occurs through 100 hours after the start of the reaction. The process indicators, see table.

Example 3.

The process is conducted as in example 1, the difference is that the reaction by-products (MDGP to 0.055 g/h and DMD 0.008 g/h) is separated and recycled, adding to the original thread formalin 0,43 g/h and tertbutanol 1.55 g/H. the Reaction is carried out for 3 hours. At the exit of the reactor discovered the following main products: tertbutanol 0.34 g/h, isobutylene 0,67 g/h, isoprene 0.24 g/h, MDGP 0,062 g/h, DMD 0.01 g/H. the Obtained results correspond to the yield of isoprene on turned formaldehyde 68% conversion of formaldehyde to 100%. The yield of isoprene in the transformed derivatives of isobutylene (TBS and isobutylene) is 80%. These results show the possibility of recycling intermediates of the reaction.

Example 4.

The process is conducted as in example 1, the difference is that the reaction by-products (MDGP 0.55 g/h and DMD 0,08 g/h) is separated and added to the stream tertbutanol 1,685 g/H. the Reaction is carried out for 3 hours. At the exit of the reactor discovered the following main products: isobutylene 0,945 g/h, tertbutanol 0.27 g/h, isoprene 0,48 g/h, MDGP 0.11 g/h, DMD 0,016 g/h the results Obtained correspond to the output of isoprene in the transformed intermediates 70% conversion of intermediates of 80%. The yield of isoprene in the transformed derivatives of isobutylene (TBS and isobutylene) and transformed intermediates is 90%. D. the nnye results show the possibility of decomposition of the intermediates on the catalyst.

Example 5 (comparative).

The process is conducted as in example 1, the difference lies in the fact that, as the catalyst used ion-exchange resin Amberlyst-15 (prototype JP 59-025337). The process indicators are also presented in the table.

Example 6 (comparative).

The process is conducted as in example 4, the difference lies in the fact that measurement of process parameters occurs after 100 hours after the start of the reaction. Process indicators presented in the table.

The analysis of the results shows the advantages of the proposed method of producing isoprene (app.1-4) compared with the prototype PR, 6). The results imply that the use of ion-exchange resin is not provided a high yield of isoprene and stability of the catalyst.

Further, in the examples shown the possibility of the implementation processes with all the catalysts specified in the formula, under different process conditions.

Example 7.

The process is conducted as in example 1, the difference lies in the fact that as the catalyst use phosphate tantalum (TaOPO4).

Example 8.

The process is conducted as in example 1, the difference lies in the fact that, as the catalyst used zirconium phosphate supported on a carrier (silica gel).

Example 9.

Similar to example 1, the difference lies in the fact that the process is carried out at 100°C.

Example 10. Similar to when the ERU 1, the difference is that the process is carried out at 200°C.

Example 11.

Similar to example 1, the difference lies in the fact that submit formalin speed of 0.43 g/h and 0.38 g/h tertbutanol when the ratio tertbutanol/formaldehyde =1.

Example 12.

Similar to example 1, the difference lies in the fact that submit formalin speed of 0.43 g/h and 7.7 g/h tertbutanol when the ratio tertbutanol/formaldehyde =20.

Example 13.

Similar to example 1, the difference lies in the fact that submit formalin speed of 0.43 g/h, and 1.15 g/h of isobutene with a ratio of isobutylene/formaldehyde =4.

Example 14.

Similar to example 1, the difference lies in the fact that the process is carried out at a pressure of 7 ATM.

Example 15.

Similar to example 1, the difference lies in the fact that the process is carried out at a pressure of 20 ATM.

Example 16.

Similar to example 1, the difference lies in the fact that submit formalin with the speed of 0.11 g/h and 0.39 g/h tertbutanol when the ratio tertbutanol/formaldehyde =4.

Example 17.

Similar to example 1, the difference lies in the fact that submit formalin with a speed of 3.3 g/h and 11.7 g/h tertbutanol when the ratio tertbutanol/formaldehyde =4.

Examples 9-17 illustrate the possibility of implementing a method of producing isoprene in a wide range of variation interaction conditions.

So the m way presents examples confirm the achievement of the technical result concerning the possibility of achieving a high yield and selectivity of the formation of isoprene conditions of liquid-phase reaction in the absence of reagents and catalysts, cause corrosion of equipment and the production of large quantities of by-products of the interaction.

1. The method of liquid-phase production of isoprene by the interaction of formaldehyde with isobutylene or its derivatives in the presence of a solid catalyst and subsequent selection of the target product, wherein the catalyst used phosphate selected from phosphates of zirconium, niobium or tantalum, and the interaction is carried out at 100-200°C., a pressure of 7 to 20 MPa, and a molar ratio of isobutylene or isobutylene derived to formaldehyde equal to (1-20)/1.

2. The method according to claim 1, characterized in that as isobutylene derived using tributyl alcohol, methyl tertiary butyl ether, ethylcelluloses ether or mixtures thereof.

3. The method according to claim 1, characterized in that after the interaction of formaldehyde with isobutylene or its derivatives formed by-products are separated from the target product and recycle in the head in the process.

4. The method according to claim 1, characterized in that after the cos is deystviya formaldehyde with isobutylene or its derivatives carry out the separation of by-products formed and their decomposition in the solid-phase catalyst, containing phosphates of zirconium, niobium or tantalum.

5. The method according to any of PP or 4, characterized in that the by-products of the interaction of formaldehyde with isobutylene or its derivatives are 4,4-dimethyldioxanes-1,3, methyldihydromorphine or a mixture of the above substances with isobutylene or its derivatives.

6. The method according to claim 1, characterized in that the phosphates of zirconium, niobium or tantalum using deposited on an inorganic carrier.

7. The method according to claim 1, characterized in that the process is carried out in continuous flow reactor with a fixed catalyst bed.



 

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1 cl, 19 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to production of catalysts, specifically to production of catalysts for synthesis of isoprene by reacting methylal and isobutylene. Described is a catalyst for synthesis of isoprene by reacting methylal and isobutylene, containing boron phosphate, as well as an aluminium-magnesium and/or aluminium-zinc spinel in the following content of components, wt %: aluminium-magnesium and/or aluminium-zinc spinel 40-90; boron phosphate - the rest. Described also is a catalyst for synthesis of isoprene by reacting methylal and isobutylene, containing boron phosphate which also contains an aluminium-magnesium and/or aluminium-zinc spinel and at least one oxide or a compound easily decomposed to an oxide, selected from aluminium, magnesium, zinc, cerium, lanthanum, praseodymium, silicon, calcium, vanadium and molybdenum, with the following content of components, wt %: aluminium-magnesium and/or aluminium-zinc spinel 63-90; boron phosphate 1-32; oxides or compound easily decomposed to oxides, selected from aluminium, magnesium, zinc, cerium, lanthanum, praseodymium, silicon, calcium, vanadium and molybdenum 1-20.

EFFECT: high selectivity and resistance to water vapour.

4 cl, 12 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: object of the present invention is to develop method for making catalyst to produce methacrylic acid by gaseous catalytic oxidation of metacrolein, isobutyl aldehyde or isobutyric acid. There is disclosed method for making catalyst to produce methacrylic acid by gaseous catalytic oxidation of metacrolein, isobutyl aldehyde or isobutyric acid, involving as follows: (a) the stage of mixing water and compounds, each containing any Mo, V, P, Cu, Cs or NH4, to prepare aqueous solution or dispersed compounds (further, both mentioned as a suspension); (b) the stage of drying suspension produced at the stage (a), to make dry suspension; (c) the stage of burning dry suspension produced at the stage (b), to make burnt substance; (d) the stage of filtrating mixed burnt substance produced at the stage (c) and water to separate aqueous solution and water-insoluble substance; and (e) the stage of drying water-insoluble substance produced at the stage (d) to make dry water-insoluble substance; and (f) the stage of coating the carrier with dry water-insoluble substance produced at the stage (e), with using a binding agent to make coated mould product, and (g) the stage of burning coated mould product produced at the stage (f) in inert gas atmosphere, in the air or with reducing agent added.

EFFECT: making catalyst with long life, high activity and selectivity.

8 cl, 9 tbl, 9 ex

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