A method of producing isoprene from isobutene contained in hydrocarbon mixtures, and formaldehyde
(57) Abstract:The invention relates to a method of producing isoprene from isamuanoguchi4hydrocarbon mixtures and formaldehyde by chemical transformations in the presence of acid water-soluble and/or solid catalyst in at least three reaction zones, the first of which carry out the extraction isobutene from hydrocarbon mixtures by hydration, the second is the formation of intermediates that are able to further decompose into isoprene, and the third decomposition intermediates and subsequent separation obtained in this zone, the reaction mixtures and recycling at least part of the selectable isobutene in the area of synthesis intermediates, with part of the source of formaldehyde is fed to the area extraction isobutene, the reaction mass is specified zone rasclaat water and organic flow, water flow, containing at least tertbutanol, 3-methylbutanol-1,3 4,4-dimethyldioxanes-1,3, and the rest of the source of formaldehyde is directed to the zone of the synthesis intermediates of synthesis intermediates deduce aqueous and organic streams that are sent to the zone of decomposition may previously passing through the zone of hydrolysis, and the organization and hydrocarbon, C4containing at least tertbutanol and 4,4-dimethyldioxanes-1,3, directed to the area of synthesis intermediates, and/or in the zone of expansion, and/or in the zone of hydrolysis. Alternatively, in the zone of extraction isobutene introduce a non-tertiary alcohol with the number of carbon atoms from 2 to 6. The technical result is the optimal relationship between the processes of extraction isobutene and synthesis of isoprene, which simplifies the method and makes it economical. 7 C.p. f-crystals, 2 tab., 2 Il. The invention relates to the field of production of isoprene monomer to synthetic rubbers.More specifically the invention relates to the field of production of isoprene from isamuanoguchi hydrocarbon mixtures and formaldehyde.The known method [in the book. Synthetic rubber, L., Chemistry, 1976, S. 696-709] production of isoprene from isamuanoguchi mixtures of hydrocarbons, C4and formaldehyde by contacting in the presence of aqueous solutions of strong acids with primary education 4,4-dimethyldioxanes-1,3 with subsequent separation of the reaction mixtures, distillation of the unreacted hydrocarbons, allocation of concentrated 4,4-dimethyldioxanes-1,3, its thermal decomposition and the release of isoprene jixana-1,3 carried out at a large molar excess of formaldehyde with respect to isobutene (2:1) and high concentrations of formaldehyde. As a consequence, in the scheme of the process have to include expensive site selection and concentration of formaldehyde;
the method requires cost allocation concentrated 4,4-dimethyldioxanes-1,3;
- gas-phase decomposition of 4,4-dimethyldioxanes-1,3 carried out at high temperature (370-390oC) and is very energy intensive.The known method [U.S. Pat. EN N 1216940, 20.03.1996,] production of isoprene from concentrated isobutene and/or tertiary butanol and formaldehyde in the presence of acid catalyst in two serially connected reactors, operating at different temperatures: first, preferably at 100-130oC and the second preferably at 165-180oC; in the first reactor is mainly the formation of intermediates that are able to further decompose with the formation of isoprene, and the second to decompose with the formation and subsequent separation of isoprene.The disadvantage of this method is the need to use a concentrated isobutene and/or tert-butanol. Getting them from the available raw material sources (and they usually are IsolatedStorage mixture of hydrocarbons, C4requires complex and highly energy-intensive procedures.
4with water in the presence of an acid catalyst, followed by separation of the resulting tert-butanol by rectification and its interaction with formaldehyde in the presence of an acid catalyst at elevated temperature and pressure with subsequent separation of the reaction mass and the release of isobutane recycled in the area of synthesis of isoprene, and the resulting isoprene. As can be seen from the examples in the patent RU 2099319 examples, the synthesis of isoprene from selected tert-butanol and enter the formaldehyde is carried out in two successive reaction zones, the first of which (operating at a lower temperature than the subsequent area) are formed intermediates, including 4,4-dimethyldioxanes-1,3, and the second is to decompose with the formation of isoprene and isobutene, accompanied by the formation of side products.In General, taking into account the interaction areas of isobutene with water, obtaining isoprene is carried out using at least three reaction zones. As for the acid catalyst, in U.S. Pat. EN 2099319 (in the examples) are used as water-soluble and solid acid catalysts.With the burly(s) of the mixture(s) by hydration, carried out by feeding a large amount of water. In all the examples of said patent when retrieving isobutene from C4-mix with his 42,6% content in the area of hydration serves 14500 g of pure water at 2400 g C4-mixtures (i.e., 142 g of water per 1 g of isobutene contained in the original C4-mix). Of hydration of a mixture of tert-butanol extracted through a very complicated procedure, including extraction of parts of tert-butanol from aqueous solution by a stream of isobutene and then two rectification: one for the distillation of hydrocarbons (isobutane) extracted from tert-butanol and the other for the distillation of the remaining tert-butanol from aqueous solution (in the form of an azeotrope with water).We unexpectedly found to be very economical and simple method based on the use of optimal technological interrelations between the processes of extraction isobutene and synthesis of isoprene.We offer a method of producing isoprene from isamuanoguchi C4hydrocarbon mixtures and formaldehyde by chemical transformations in the presence of acid water-soluble and/or solid catalyst in at least three reaction zones, the first of which carry out the extraction isobutene from hydrocarbon SMEs isoprene, and the third primary decomposition of intermediates and subsequent separation obtained in this zone, the reaction mixtures and recycling at least part of the selectable isobutene in the area of synthesis intermediates, namely, that part of the source of formaldehyde is fed to the area extraction isobutene, the reaction mass is specified zone rasclaat on aqueous and organic streams, water stream containing at least tert-butanol, 3-methylbutanol-1,3 4,4-dimethyldioxanes-1,3, and the rest of the source of formaldehyde is directed to the zone of the synthesis intermediates of synthesis intermediates deduce aqueous and organic streams, refer to the zone of decomposition may previously passing through the zone of hydrolysis, and the organic flow zone extraction isobutene served in the node distillation of hydrocarbon, C4and the residue after distillation of hydrocarbon, C4containing at least tert-butanol and 4,4-dimethyldioxanes-1,3, directed to the area of synthesis of intermediates and/or the zone of expansion, and/or the zone of hydrolysis.As a variant of the proposed method lies in the fact that in the area of extraction isobutene introduce a non-tertiary alcohol with the number of carbon atoms from 2 to 6, and after the distillation of hydrocarbons C
RI - reactor extraction isobutene from a hydrocarbon mixture, RS - reactor synthesis intermediates, PP - reactor decay intermediates in the isoprene, the WG - hydrolysis reactor, distillation column, the sump-separator.According Fig. 1 hydrocarbon mixture F (stream 1) is fed into the reactor extraction isobutene. It also serves a return water flow 2 may contain an acid catalyst and corrosion inhibitors, and an aqueous solution of formaldehyde (stream 3), and, possibly, the flow of non-tertiary alcohol(s) STC (stream 4) and additional (compensatory losses) flow of water (stream 2A) and the acid solution of RK (stream 2B).After leaving the reaction zone is stratification of the mixture and a stream 5 containing water and dissolved components, is fed to the synthesis reactor of the RS, and the organic stream 6 enters the distillation OK mainly containing tert-butanol, DME and possibly non-tertiary alcohol (stream 8), which serves preferably in the synthesis reactor RS and/or the decomposition reactor PP.In the reactor RS being recirculated from the node separation flow isobutene (thread 15A), preferably an aqueous solution of formaldehyde (stream 3') and possibly recycled from a node split streams containing tert-butanol, DME, MDGP and other by-products. From the reactor RS output water stream 9 and the organic stream 10, which is sent to the decomposition reactor PP, possibly passing through the pre-hydrolysis reactor WG (shown dotted). With these flows in PP (possibly pre-WG) can be directed part recycled from a node split flow isobutene (thread 15B).In PP is preferably introduced also stream 11 containing hydrocarbon solvent.From the reactor PP deduce liquid water ("water-acid") stream 12, which is directed preferably after the distillation of the water and cleaning (designated as site cleanup) in RI and/or CL, and gas-phase stream 13 containing isoprene, isobutene and the number of oxygen-containing substances) and liquid-phase organic Riccione zone.From the node separation derive several threads with a predominant content of certain substances: isobutane IB (stream 15), isoprene (stream 16), tert-butanol TB (stream 17), MDGP (stream 18), water (stream 19), non-tertiary alcohol NTS (stream 20), WFP (stream 21), perhaps DMD (stream 22) and the hydrocarbon solvent (stream 23).According Fig. 2, in contrast to Fig. 1, the process in the reactor extraction isobutene (RI) performed with partial evaporation of the reaction mixture. Feed streams are marked similarly to Fig. 1. The top of the reactor RI output vapor stream 6', which after condensation return to the entrance of the RI (stream 6A) or/and sent to distillation column K-1 (stream 6B). In K-1 serves organic layer (stream 6), obtained by separation in a settling tank separator "About" liquid mass flowing out of the reactor RI.The aqueous layer (stream 5) from the pit "On" served in the synthesis reactor RS.Also, in contrast to Fig. 1, the output from the synthesis reactor RS organic stream 10 and possibly water stream 9 is subjected to rectification, respectively, in columns K-2 and K-3. From the stream 9 is distilled methanol-metallinou mixture MM (thread 9A), and the flow 10 - Isobutyraldehyde stream 10A, which return to the WMO is of the reactor PP with a distillation of the core products at the top and output of water flow from the cube.Example 1.Processing is carried out in accordance with Fig. 1.As a source of isobutene use isobutane-Isobutanol mixture obtained by dehydrogenation of isobutane containing 45% of isobutene.Formaldehyde is served in the form of a 40% solution in water.As the catalyst in the reactors RI, RS and RR are placed sulfonation Amberlyst-35.Process data are given in table. 1.Example 2.Processing is carried out in accordance with Fig. 2.As a source of isobutene use C4-fraction of pyrolysis (after removing 1,3-butadiene) containing 45% of isobutene.Formaldehyde is served in the form of a 40% solution in water.As catalyst, use phosphoric acid (FC) with the addition of corrosion inhibitors.As substances that increase the mutual solubility of hydrocarbons and water in the reactor RI introduce n-butanol.As the hydrocarbon solvent in the reactor RR use mixtures of alkenes with a boiling point of 150 to 200oC.Process data are given in table. 2. 1. A method of producing isoprene from isamuanoguchi