RU2578598C2 - Process for preparing methyl propionate and methyl methacrylate - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to processes for conversion of hydrocarbon gas to produce liquid chemical products with high added value. Method for processing natural or associated gas and hydrocarbon petroleum gas with a high content of heavy homologues of methane and low methane number, to obtain methyl propionate and methyl methacrylate, is two-stage selective direct homogeneous oxidation of hydrocarbon gas and subsequent catalytic carbonylation mixture to form methyl propionate, condensation portion obtained methyl propionate with formaldehyde to produce methyl methacrylate, and at one stage of oxidation of hydrocarbon gas, conducted at temperature of 700-800 °C and pressure of 1-30 bar, gas mixture containing ethylene and CO, and other steps performed at pressure of 30-80 bar and initial temperature of 350-420 °C, produced methanol and CO, wherein the first or hydrocarbon gas is oxidized at step carried out at temperature of 700-800 °C, to obtain ethylene and then oxidized in step conducted at initial temperature of 350-420 °C, first hydrocarbon gas is oxidized on stage carried out at initial temperature of 350-420 °C, followed by condensation of resulting methanol, formaldehyde and water, and then resultant oxidized gas mixture at step carried out at temperature of 700-800 °C, followed by addition of methanol first stage; and then resultant mixture was treated with two-step oxidation at elevated temperatures and pressures in presence of catalyst for carbonylation reaction of ethylene, methanol and CO, and hydrocarbon gas is obtained with high methane number and liquid products from which methyl propionate was isolated, portion of which is further treated with formaldehyde. Method for processing natural or associated gas and hydrocarbon petroleum gas with a high content of heavy homologues of methane and a low methane number, to obtain methyl propionate and methyl methacrylate, is selectively direct the homogeneous oxidation of hydrocarbon gas and subsequent catalytic carbonylation mixture to produce methyl propionate, condensation of the resulting methyl propionate with formaldehyde to produce methyl methacrylate, with a portion of the hydrocarbon gas is subjected to an oxidative conversion step carried out at a pressure of 30-80 bar and the initial temperature of 350-420 °C, followed by condensation of the liquid products and recovering the methanol and another portion of the hydrocarbon gas is subjected to an oxidative conversion step carried out at a temperature of 700-800 °C and a pressure of 1-30 bar to give a gas mixture containing ethylene and CO, which, after cooling, was bubbled through the resulting methanol in the presence of a catalyst for the carbonylation reaction of ethylene, methanol and CO at elevated temperatures and pressures to give a hydrocarbon gas with a high methane number and liquid products from which the methyl propionate was isolated, a portion of which is further treated with formaldehyde.

EFFECT: technical result is more simple and economical process for preparing desired products while obtaining purified "dry" gas with increased compared to starting hydrocarbon gas methane number.

2 cl, 3 ex

Description

The invention relates to processes for processing hydrocarbon gases to produce liquid chemical products with high added value (gas-to-liquid processes), in particular, to the production of methylpropionate used in the chemical industry as a solvent and intermediate for the synthesis of a number of products. A particularly promising process in which methylpropionate is used is an alternative way to obtain one of the most important products - methyl methacrylate (MMA). Currently, methyl methacrylate is obtained by the acetone cyanohydrin method, the initial intermediates of which are acetone and hydrogen cyanide [Chemical Encyclopedia. M., 1998. Scientific from BDT. T. 5, p. 510]. The disadvantage of this method is the use of expensive and toxic raw materials, as well as a large amount of toxic effluents and waste.

There is also an alternative method for producing methyl methacrylate by condensation of methyl propionate with formaldehyde in the presence of catalysts [US Patent 3089902]. One way to obtain methyl propionate is the interaction of ethylene with CO in the presence of methanol on a catalyst containing nickel carbonyl [DE Patent 915567, 1953, BASF].

The closest in technical essence and the achieved result is a method for producing methyl methacrylate from simple chemicals: ethylene, methanol and carbon monoxide through the stage of producing methyl propionate by methoxycarbonylation of ethylene followed by condensation with formaldehyde (Lucite’s Alpha technology - Alpha MMA - Lucite International process) [ GR Eastham, Μ. Waugh and Ph.-I. Richards, Lucite International UK Limited, "Carbonylation of ethylenically unsaturated compounds", WO Patent 2007/057640 A1; 2007]):

Compared with the above method, this process is 30-40% cheaper in terms of investment and produces MMA with virtually no waste.

The central stage of this process is the production of methyl propionate by methoxycarbonylation of ethylene. A large number of catalysts have been proposed, mainly based on palladium complexes, which, in contrast to the cobalt and nickel complexes active in this reaction at temperatures of 150-200 ° C and pressures of 150-200 bar, catalyze the process at 70-120 ° C and pressure below 100 bar. For example, in the presence of a catalytic system containing 1,2-bis (di-mpem-butyl-methyl-phosphino) benzene, palladium salts and sulfonic acid additives, ethylene methoxycarbonylation proceeds at 80 ° C and a pressure of 10 bar at a speed of 50,000 mol / mol [Pd] × h with 99.98% methyl propionate selectivity. [R.A.M. Robertson, D.J. Cole-Hamilton / Coordination Chemistry Reviews 225 (2002) 67-90. The production of low molecular weight oxygenates from carbon monoxide and ethane].

It is also known [S. Bianchini, A. Meli, W. Oberhauser et. al Methoxycarbonylation of Ethene by Palladium (II) Complexes with 1,1′-Bis (diphenylphosphino) ferrocene (dppf) and 1,1′-Bis (diphenylphosphino) octamethylferrocene (dppomf) Organometallics, 2003, 22 (12), pp 2409- 2421] that the squared Pd (II) complexes: [Pd (H ₂ O) ₂ (dppf)] (OTs) ₂ and [Pd (H ₂ O) ₂ (dppomf)] (OTs) ₂ are effective catalysts for ethylene methoxycarbonylation, but they exhibit different selectivity, and the catalyst with 1,1′-bis (diphenylphosphino) octamethylferrocene ligand gives exclusively methyl propionate. Reaction conditions: temperature 85 ° C, pressure 40 bar, ratio CO: C ₂ H ₄ 1: 1, catalyst concentration - 10 ^-4 M.

The disadvantage of the proposed method for producing methyl propionate and methyl methacrylate is the need to organize the independent production of each individual component of the reaction: ethylene, methanol and CO, and to obtain methyl methacrylate - additional formaldehyde. Ethylene, as is known, is mainly obtained by thermal pyrolysis of petroleum fractions (naphtha), methanol is obtained from synthesis gas, which, in turn, is obtained by steam or oxidative conversion of a "dry" (methane) gas. The source of CO is also synthesis gas containing, in addition to CO, hydrogen in a ratio of 1: 2 or higher. To obtain formaldehyde, another production of methanol oxidation is necessary.

The technical result of the claimed invention is the improvement of the method of producing methyl propionate and methyl methacrylate, aimed at obtaining all the starting compounds for producing methyl propionate from one raw material by processing associated petroleum and natural gases with a high content of methane homologues ("fatty gases") in a single technological cycle while purifying the raw materials gas from methane homologues, that is, the creation of a simpler and more economical way to obtain the target products while obtaining purified "dry" gas with increased relative to the starting hydrocarbon gas methane number.

The specified technical result is achieved by the fact that the processing of natural and associated petroleum gases, as well as hydrocarbon gases with a high content of heavy methane homologues and a low methane number, is carried out by two-stage direct homogeneous oxidation of the hydrocarbon gas and subsequent carbonylation of the mixture to obtain the target products, and in one step oxidation carried out at a temperature of 700-800 ° C and a pressure of 1-30 bar receive a gas mixture containing ethylene and CO, and at another stage carried out at At 30-80 bar, and an initial temperature of 350-420 ° C, methanol and CO are obtained, the resulting mixture is treated at elevated pressures and temperatures in the presence of carbonylation catalysts, and hydrocarbon gas with an increased methane number and liquid products, of which by known methods, are obtained methylpropionate is isolated, part of which is further treated with formaldehyde.

Various options for the implementation of the stages of the oxidation process and the combination of oxidation and carbonylation processes are possible:

- initial oxidative conversion of a light hydrocarbon gas feed at temperatures above 700 ° C to produce ethylene and subsequent oxidative conversion of the gas mixture at temperatures of about 400 ° C and pressures above 20 bar to produce additional methanol and formaldehyde;

- initial oxidative conversion of a light hydrocarbon gas feed at temperatures of about 400 ° C and pressures above 20 bar to produce methanol and formaldehyde, condensation of methanol, formaldehyde and water, and subsequent oxidation of the gas mixture at temperatures of about 700 ° C with additional production of ethylene;

- the parallel implementation of the stages of oxidative conversion of part of the feed gas at temperatures above 700 ° C and oxidative conversion of another part of the feed at temperatures of about 400 ° C and pressures above 20 bar.

Methyl propionate is isolated from liquid products by known methods. To obtain methyl methacrylate, the purified methyl propionate is treated with formaldehyde, which is also obtained at the stage of direct oxidation of the initial hydrocarbon gas, or is added additionally.

Thanks to this method of the process, the organization of separate production of the starting products for the synthesis of methylpropionate is not required, since in a single technological cycle all three main raw materials necessary for the synthesis of methylpropionate are obtained simultaneously: ethylene, methanol and CO, and at the same time they are purified from the gas phase impurities of heavy components hydrocarbon gas with a higher methane number compared to the original hydrocarbon gas, which can be used as fuel on for power plants. At the same time, a small amount of formaldehyde will also be obtained, which, with formaldehyde additionally introduced from the outside, is used in the subsequent stage of methyl methacrylate production by condensation of methyl propionate with formaldehyde.

Previously, such options for organizing the process of simultaneous production of olefins, methanol and CO and subsequent carbonylation of the resulting mixture to produce valuable liquid products with high added value and hydrocarbon gas with a higher methane number compared to the source hydrocarbon gas in a single technological cycle were not considered in the patent literature. The problem is especially relevant for Russia with its huge reserves of associated petroleum and "fat" hydrocarbon gases

Examples of the proposed method.

Example 1

Example 1. A mixture of hydrocarbon gases of the composition: methane - 93.7%, ethane - 6.3% (methane number - 84) at a pressure of 30 bar and a flow rate of 400 l / h, is subjected to oxidative conversion at a temperature of 740 ° C with technical oxygen, which is supplied in the amount of 80 l / hour. The gas mixture obtained in the first stage of oxidation, containing unreacted methane and ethane, ethylene, CO, methanol and impurities, is cooled, compressed to a pressure of 70 bar and fed to the second stage, in which, at an initial temperature of 400 ° C, oxidative conversion with the participation of oxygen is carried out, which is fed into the reactor, divided into two sections, in portions in an amount of 11.2 l / h each. As a result of oxidation, a gas mixture is obtained in an amount of 520 l / h, containing (% by volume) 1.9% ethylene, 2.5% methanol, 7.1% carbon monoxide, 16.3% water, 65.5% methane, 3 9% hydrogen. The mixture is cooled to a temperature of 200 ° C and further treated with the participation of carbonylation catalysts, while CO interacts with ethylene and methanol to form methyl propionate, which is condensed in the form of an aqueous-alcohol-formaldehyde solution, from which 35 g / h of methyl propionate are isolated by known methods; the specified solution is separated from the gas product, which is purified from ethane impurities hydrocarbon gas in an amount of 400 l / h, having a composition of 85% methane, 6.7% carbon monoxide, 5% hydrogen, 2.3% carbon dioxide, 1% nitrogen, having a methane number of 95.

By the interaction of the obtained methyl propionate with formaldehyde coming from external sources, methyl methacrylate is obtained by known methods.

Example 2. A hydrocarbon-containing gas of the composition: methane - 88.2% ethane - 11.7% (vol.) At a pressure of 30 bar in an amount of 500 l / h is heated to a temperature of 350 ° C and subjected to oxidation with technical oxygen, which is fed in two sections oxidation in total in the amount of 36 l / h. As a result of partial oxidation, a gas mixture is obtained in an amount of 550 l / h, containing (% vol) 2.4% methanol, 1.4% formaldehyde, 0.4% ethanol, 3.6% carbon monoxide, 4.0% water, 82.2% methane, 5.1% ethane, 0.4% nitrogen. The gas mixture is cooled to a temperature of 0-20 ° C and the liquid phase is separated in an amount of 52 g, containing 10 g of formaldehyde, 18 g of methanol, 17 g of H ₂ O, 5 g of ethanol. The remaining gas is heated to a temperature of 700 ° C and subjected to oxidative conversion in the second stage of oxidation at a temperature of 750 ° C with technical oxygen, which is supplied in an amount of 15 l / h. As a result of oxidative conversion, a gas mixture is obtained in an amount of 525 L / h, containing (% by volume) 2.0% ethylene, 0.25% propylene, 6.6% carbon monoxide, 0.25% water, 86.2% methane, 3.9% hydrogen. The mixture is cooled to a temperature of 200 ° C, methanol of the first stage is added and it is further treated with the participation of carbonylation catalysts, while CO interacts with ethylene and methanol to form methyl propionate, which is condensed in the form of an aqueous-alcohol solution. The resulting solution is separated from the gas product and 39.5 g / h of methyl propionate are isolated from it by known methods, part of which is further treated with first-stage formaldehyde and 27 g / h of methyl methacrylate are obtained. At the same time, a gas stream of the second oxidation stage is obtained in an amount of 500 l / h, containing 90% methane, 0.6% ethane, 4.5% carbon monoxide, 4% hydrogen, 1% carbon dioxide, having a methane number of 95.

Example 3. A hydrocarbon-containing gas of the composition: CH ₄ - 82%, C ₂ H ₆ - 6%, C ₃ H ₈ - 8%, C ₄ H ₁₀ - 4% (methane number of the mixture 54) in an amount of 2000 l / h is divided into two flows, each at 1000 l / h. One gas stream is subjected to homogeneous partial oxidation at a pressure of 40 bar and an initial temperature of 350 ° C with technical oxygen, which is supplied in an amount of 332.5 l / h, followed by condensation of liquid products and with recirculation of a part of the gas after oxidation in an amount of 5000 l / h. As a result of oxidation, a stream of liquid products is obtained in an amount of 400 g / h containing 160 g / h of methanol and 37.5 g / h of formaldehyde and an exhaust gas stream in an amount of 1135 l / h containing 72% methane, 21% carbon monoxide, 3.3 % ethane, 1.3% propane, 1.5% nitrogen. Pure methanol in the amount of 155 g / h is isolated from the liquid product stream by rectification.

Another stream of hydrocarbon feed gas is heated to a temperature of 700 ° C and subjected to oxidative conversion in the second stage of oxidation at a temperature of 750 ° C with technical oxygen, which is supplied in an amount of 170 l / h. As a result of oxidative conversion, a gas mixture is obtained in an amount of 1350 l / h, containing (% by volume) 6.8% ethylene, 0.8% propylene, 8.4% carbon monoxide, 10.2% water, 64.0% methane, 3.3% hydrogen, 2.4% oxygen.

The mixture is cooled to a temperature of 200 ° C, compressed and further processed by sparging at a pressure of 40 bar through methanol of the first stage with the participation of carbonylation catalysts; in this case, CO interacts with ethylene and methanol to form methyl propionate, which is condensed in the form of an aqueous-alcohol solution. The resulting solution is separated from the gas product and 342 g / h of methylpropionate are isolated from it by known methods. The gas stream after the second stage of oxidation in an amount of 995 l / h, containing 86% methane, 3.6% ethane, 1.5% carbon monoxide, 4% hydrogen, is combined with the gas stream after the first stage of oxidation in an amount of 1135 l / h, containing 72% methane, 21% carbon monoxide, 3.3% ethane, 1.3% propane, 1.5% nitrogen, and get hydrocarbon gas in an amount of 2120 l / h (methane - 79%, ethane - 3.5%, propane - 1%, СО - 11.6%), hydrogen - 2%, 3% - inert gases) with a methane number of 84 higher than the initial hydrocarbon gas (54).

By the interaction of the obtained methyl propionate with formaldehyde coming from external sources, methyl methacrylate is obtained by known methods.

Compared with the known method, the claimed invention allows to achieve a significant simplification of the technology, reducing capital costs by reducing the number of production facilities and eliminating the highly energy and capital-intensive stage of synthesis gas production, and also provides the possibility of simultaneously obtaining purified from impurities heavy hydrocarbon gas components with more high methane number compared to the original hydrocarbon gas, which can be used as fuel for power plants.

Claims (2)

1. A method of processing natural and associated petroleum gases, as well as hydrocarbon petroleum gases with a high content of heavy methane homologues and a low methane number, to obtain methyl propionate and methyl methacrylate, which consists in a two-stage selective direct homogeneous oxidation of hydrocarbon gas and subsequent catalytic carbonylation of the mixture to obtain methyl propionate, condensation of a part of the obtained methyl propionate with formaldehyde to obtain methyl methacrylate, moreover, at one oxidation stage of carbohydrate of a hydrogen gas conducted at a temperature of 700-800 ° C and a pressure of 1-30 bar, a gas mixture is obtained containing ethylene and CO, and at another stage, conducted at a pressure of 30-80 bar and an initial temperature of 350-420 ° C, methanol is obtained and CO, and either the hydrocarbon gas is first oxidized at a stage carried out at a temperature of 700-800 ° C to produce ethylene, and then it is oxidized at a stage carried out at an initial temperature of 350-420 ° C, or the hydrocarbon gas is first oxidized at a stage carried out at an initial temperature of 350-420 ° C, with subsequent condensation obtained of methanol, formaldehyde and water, and then the resultant oxidized gas mixture at step carried out at a temperature of 700-800 ° C, followed by addition of methanol the first stage; then the mixture obtained as a result of two-stage oxidation is treated at elevated pressures and temperatures in the presence of a carbonylation catalyst for the interaction of ethylene, methanol and CO, and a hydrocarbon gas with an increased methane number and liquid products are obtained from which methyl propionate is isolated, some of which is further treated with formaldehyde. 2. A method of processing natural and associated petroleum gases, as well as hydrocarbon petroleum gases with a high content of heavy methane homologues and a low methane number, to obtain methyl propionate and methyl methacrylate, which consists in selective direct homogeneous oxidation of hydrocarbon gas and subsequent catalytic carbonylation of the mixture to obtain methyl propionate, condensation part of the obtained methyl propionate with formaldehyde to obtain methyl methacrylate, and part of the original hydrocarbon gas is subjected to oxidative conversion at the stage carried out at a pressure of 30-80 bar and an initial temperature of 350-420 ° C, followed by condensation of liquid products and the evolution of methanol, and the other part of the initial hydrocarbon gas is subjected to oxidative conversion at the stage carried out at a temperature of 700-800 ° C and a pressure of 1-30 bar to obtain a gas mixture containing ethylene and CO, which after cooling is bubbled through the obtained methanol in the presence of a carbonylation catalyst for the interaction of ethylene, methanol and CO at elevated temperatures and yes have ramped afford hydrocarbon gas with high methane number and liquid products from which the methyl propionate was isolated, a portion of which is further treated with formaldehyde.