METHOD OF PRODUCING AROMATIC HYDROCARBON CONCENTRATE FROM LIGHT ALIPHATIC HYDROCARBONS, AND INSTALLATION FOR IMPLEMENTING SAME

Abstract

(57) Abstract: The invention relates to a method and an installation for producing a concentrate of aromatic hydrocarbons from light aliphatic hydrocarbons and from mixtures thereof with oxygenates. According to the method, an initial raw material is fed into two in-series-connected reaction units, a first unit and a second unit, with zeolite catalysts based on a pentasil group; the reaction units arc distinguished through the conditions for converting the hydrocarbons to aromatic hydrocarbons; a mixture obtained following the reaction units is separated into a liquid fraction and a gas fraction, and the gas fraction is fed to the inlet of the first and second reaction unit. The method is characterized in that the gas fraction obtained following the reaction units is separated into a hydrogen-containing gas and into a broad fraction of light hydrocarbons, containing olefins, and in that the hydrogen-containing gas is fed into an oxygenate synthesis unit, in that the resultant oxygenates are fed to the inlet of the first and second reaction unit, and in that the broad fraction of light hydrocarbons, containing olefins, is fed to the inlet of the first reaction unit. The use of the present invention allows for increasing the efficiency of producing concentrates of aromatic hydrocarbons and for increasing selectivity in regard to alkyl benzoles, and specifically xylenes.

Claims

1-19. (canceled)

20. A method of producing an aromatic hydrocarbon concentrate from light aliphatic hydrocarbons and mixtures thereof with oxygenates, the method comprising: feeding a feedstock comprising a mixture of hydrocarbons and oxygenates into a first of two serially connected reactors, comprising the first reactor and a second reactor; the first and the second reactors contain pentasil-based zeolite catalysts, wherein the reactors differ in the conditions of conversion of hydrocarbons to aromatics; catalytically reacting the first feed stock in the first reactor to provide a first reaction product; catalytically reacting the first reaction product and added oxygenate in second reactor to provide a second reaction product; separating the second reaction product into liquid fraction and gaseous fraction; wherein the liquid fraction comprises natural gas liquids containing olefins and the gaseous fraction comprises hydrogen-containing gas; separating the hydrogen-containing gas from the gaseous fraction; feeding the natural gas liquids into the first reactor; feeding the hydrogen-containing gas into an oxygenate synthesis unit, whereby a oxygenate is produced; and, feeding the oxygenate produced by the oxygenate syntheses unit into the first, the second, or both the first and second reactors.

21. The method of claim 20, wherein, the oxygenate synthesis is effected by producing synthesis gas using autothermal reforming technology, with subsequent oxygenate synthesis by a circulating or flow-through scheme.

22. The method of claim 20, wherein, the oxygenate synthesis is effected with simultaneous fine purification of discharge hydrogen-containing gas to remove sulfur compounds.

23. The method of claim 20, wherein, a temperature of 400-500 C. is maintained in the first reactor and a temperature of 450-520 C. is maintained in the second reactor.

24. The method of claim 20, wherein the temperature in the first and second reactors is controlled by the oxygenate flow rate.

25. The method of claim 20, where the catalyst in the first reactor comprises a mechanical mixture of two zeolites, the first of which is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=20 and is pretreated with an aqueous alkali solution and modified by rare-earth oxides in quantities of 0.5-2.0% by wt. of the weight of the first zeolite, while the second is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=82, contains residual quantities of sodium oxide 0.04% by wt. of the weight of the second zeolite, and is modified by magnesium oxide in a quantity of 0.5-5.0% by wt. of the weight of the second zeolite, where the zeolites are used in a mass ratio of 1.7/1 to 2.8/1, and the binder contains at least silica and is used in a quantity of 20-25% by wt. of the weight of the catalyst.

26. The method of claim 20, where the catalyst in the second reactor comprises a mechanical mixture of two zeolites, the first of which is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=20 and is pretreated with an aqueous alkali solution and modified by rare-earth oxides in quantities of 0.5-2.0% by wt. of the weight of the first zeolite, while the second is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=82, contains residual quantities of sodium oxide 0.04% by wt. of the weight of the second zeolite, and is modified by magnesium oxide in a quantity of 0.5-5.0% by wt. of the weight of the second zeolite, where the zeolites are used in a mass ratio of 1.7/1 to 2.8/1, and the binder contains at least silica and is used in a quantity of 20-25% by wt. of the weight of the catalyst.

27. The method of claim 20, wherein the second reaction product is feed into a liquid hydrocarbon and water condenser serially connected to a three-phase product separator whereby reaction water, liquid hydrocarbons, and discharge gases are produced.

28. The method of claim 27, wherein the gases produced by the three-phase product separator undergo stripping to recover the natural gas liquids containing olefins.

29. The method of claim 20, wherein a benzene fraction, a toluene fraction or benzene-toluene fraction is removed from the second reaction product and fed to the first reactor, the second reactor or both the first and the second reactors.

30. An installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons, the installation comprising: a serially connected first reactor and second reactor; a pentasil-based zeolite catalyst; the reactors configured whereby each reactor has different conditions of conversion of hydrocarbons to aromatics; a separation unit connected to receive an output mixture from the second reactor, whereby the separation unit separates the output mixture into a liquid fraction and gaseous fraction, and wherein the separation unit comprises a liquid fraction output and a gaseous fraction output; a line connecting the gaseous fraction output to the first and second reactors; the separation unit comprising a module for separating the gaseous fraction into hydrogen-containing gas and the natural gas liquids containing olefins, and wherein the separation unit comprises a hydrogen-containing gas output; a line connecting the hydrogen-containing output to an oxygenate synthesis unit to the first reactor, the second reactor or both the first and the second reactors.

31. The installation of claim 30, wherein the oxygenate synthesis unit comprises a synthesis gas production unit adapted to production of synthesis gas by autothermal reforming technology.

32. The installation of claim 30, wherein the oxygenate synthesis unit includes a unit for fine purification of discharge hydrogen-containing gas to remove sulfur compounds.

33. The installation of claim 30, wherein the catalyst in the first reactor comprises a mechanical mixture of two zeolites, the first of which is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=20 and is pretreated with an aqueous alkali solution and modified by rare-earth oxides in quantities of 0.5-2.0% by wt. of the weight of the first zeolite, while the second is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=82, contains residual quantities of sodium oxide 0.04% by wt. of the weight of the second zeolite, and is modified by magnesium oxide in a quantity of 0.5-5.0% by wt. of the weight of the second zeolite, where the zeolites are used in a mass ratio of 1.7/1 to 2.8/1, and the binder contains at least silica and is used in a quantity of 20-25% by wt. of the weight of the catalyst.

34. The installation of claim 30, wherein the catalyst in the second reactor comprises a mechanical mixture of two zeolites, the first of which is characterized by a silicate modulus SiO.sub.2/Al.sub.1O.sub.3=20 and is pretreated with an aqueous alkali solution and modified by rare-earth oxides in quantities of 0.5-2.0% by wt. of the weight of the first zeolite, while the second is characterized by a silicate modulus SiO.sub.2/Al.sub.2O.sub.3=82, contains residual quantities of sodium oxide 0.04% by wt. of the weight of the second zeolite, and is modified by magnesium oxide in a quantity of 0.5-5.0% by wt. of the weight of the second zeolite, where the zeolites are used in a mass ratio of 1.7/1 to 2.8/1, and the binder contains at least silica and is used in a quantity of 20-25% by wt of the weight of the catalyst.

35. The installation of claim 30, wherein the installation comprises a liquid hydrocarbon and water condenser installed after the first reactor and before the second reactor and a separator for separating the liquid fraction.

36. The installation of claim 30, wherein the installation comprises a liquid hydrocarbon and water condenser installed after the second reactor, serially connected to a three-phase conversion product separator into reaction water, liquid hydrocarbons, and discharge gases.

37. The installation of claim 30, wherein the installation comprises a module for stripping discharge gas to recover the natural gas liquids containing olefins installed after the three-phase separator and a module for stabilizing hydrocarbon condensate to remove the natural gas liquids from the condensate.

38. The installation of claim 30, wherein the installation comprises a circulation compressor installed after the three-phase separator.

39. The installation of claim 30, wherein the installation comprises a unit for removing a benzene fraction, a toluene fraction or a benzene-toluene fraction from the output mixture from the second reactor, said unit having an output connected to the first reactor, the second reactor, or the first and second reactors.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0046] Other distinguishing features and advantages of the invention clearly follow from the specification which is presented below for illustration purposes and is not restrictive, with references to the attached figures, in which:

[0047] FIG. 1 schematically depicts the overall view of the installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons and mixtures thereof with oxygenates according to the invention;

[0048] FIG. 2 schematically depicts the steps of the method of producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons and mixtures thereof with oxygenates according to the invention.

[0049] Pursuant to FIG. 1, the installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons and mixtures thereof with C.sub.1-C.sub.4 aliphatic alcohols, including two serially connected reactors, a first reactor 1 and a second reactor 2 with pentasil-based zeolite catalysts, where reactors 1 and 2 differ in the conditions of conversion of hydrocarbons to aromatics, and unit 3 for separating the mixture obtained after the reaction zones into a liquid fraction containing C.sub.5+ and water and a gaseous fraction containing H.sub.2, C.sub.1-C.sub.2 and C.sub.2-C.sub.5, i.e., olefin-containing NGL. The NGL output is connected to the inputs of the first and second reactors.

[0050] Unit 3 for separating the mixture obtained at the output of the second reactor into liquid and gaseous fractions contains module 4 for separating the gaseous fraction into hydrogen-containing gas containing mainly hydrogen, methane, and ethane, and NGL containing C.sub.2-C.sub.5 olefins and paraffins.

[0051] The installation additionally includes oxygenate synthesis unit 5, whose input is connected to the hydrogen-containing gas output of gaseous fraction separation module 4, and the output of oxygenate synthesis unit 5 is connected to the input of the first and second reactors. Oxygenate synthesis unit 5 includes synthesis gas unit 6, adapted to the production of synthesis gas by autothermal reforming technology.

[0052] Oxygenate synthesis unit 5 also includes unit 7 for fine purification of discharge hydrogen-containing gas to remove sulfur compounds.

[0053] The purpose of unit 7 for fine purification to remove sulfur compounds is the chemosorptive or adsorptive purification of hydrogen-containing gas to remove sulfur compounds in order to meet requirements for sulfur content of crude hydrocarbons defined by requirements for prereforming, reforming, and oxygenate synthesis catalysts. In addition, oxygenate synthesis unit 5 includes unit 8 for oxygenate synthesis from synthesis gas by a flow-through and/or circulating scheme.

[0054] The preferable method of synthesizing oxygenates in oxygenate synthesis unit 5 is to obtain synthesis gas by autothermal refining technology, with subsequent oxygenate synthesis by a flow-through and/or circulating scheme.

[0055] Unit 6 consists of steam-oxygen (autothermal) conversion, prereforming, and heat recovery sections (not shown in FIG. 1). The purpose of the steam-oxygen (autothermal) conversion, pre-reforming, and heat recovery sections is to obtain synthesis gas by heating feedstock, mixing it with superheated steam, stabilizing the composition of the feedstock by adiabatic prereforming (adiabatic steam conversion and destructive hydrogenation of hydrocarbon feedstock), steam-oxygen or steam-air conversion of hydrocarbon feedstock, heat recovery, and steam condensation and dewatering.

[0056] Due to the presence of hydrogen in the initial hydrocarbon feedstock (stripped discharge gases), the H/C molar ratio for the initial hydrocarbon feedstock will be 4.5 (for methane, H/C=4), which ensures the production of synthesis gas using autothermal reforming technology with a stoichiometric ratio f=(MF.sub.H.sub.2MF.sub.CO.sub.2)/(MF.sub.CO+MF.sub.CO.sub.2)2 (MF=mole fraction) at a low ratio MF.sub.CO.sub.2/MF.sub.CO0.17, which permits production of methyl alcohol with a concentration no less than 94% suitable for conversion to aromatic hydrocarbons without a concentration (distillation) stage. At lower ratios f<2, mixtures of methanol and C.sub.2-C.sub.3 aliphatic alcohols, as well as mixtures of alcohols with ethers, can be synthesized.

[0057] The purpose of unit 8 for oxygenate synthesis from synthesis gas is to produce oxygenates suitable for co-conversion with aliphatic hydrocarbons by a circulating or flow-through scheme. The most suitable method of oxygenate synthesis is oxygenate synthesis by a circulating scheme.

[0058] In addition, the ratio 2 will be met either if the mass fraction of carbon in the discharge gases is increased, which makes it possible to obtain methanol, or if the composition of discharge gases is altered while the activity of conversion catalysts declines during their service.

[0059] First and second reactors 1 and 2 include the catalyst claimed in the present invention, whose composition is described above.

[0060] The installation additionally includes unit 9 installed after first reactor 1 and before second reactor 2, consisting of liquid hydrocarbon and water condenser 10 and liquid fraction separator 11, which is connected to three-phase separator 12.

[0061] The installation additionally includes liquid hydrocarbon and water condenser 13 installed after second reactor 2, serially connected to three-phase separator 12 of conversion product to reaction water, liquid hydrocarbons and discharge gases.

[0062] The installation additionally includes module 14 installed after three-phase separator 12, designed to stabilize liquid hydrocarbons leaving 12, in which the light aliphatic hydrocarbon fraction (NGL) is distilled from the hydrocarbon condensate in addition to the fraction obtained in unit 4.

[0063] The installation additionally includes circulation compressor 14 installed after three-phase separator 12 and before gaseous fraction separation module 4.

[0064] The installation additionally includes unit 15 for extracting the benzene and/or benzene-toluene fraction from the aromatic hydrocarbon concentrate, whose output is connected to the input of first reactor 1 and/or second reactor 2.

[0065] Reactor 1 is designed for aromatization of a mixture of saturated and unsaturated aliphatic hydrocarbons and oxygenates. It contains at least one hydrocarbon feedstock heater 16, at least one hydrocarbon feedstock mixer 17, and at least one reaction zone 18.

[0066] By reaction zone here, we mean the entire reactor space in which hydrocarbon conversion occurs, including that which is divided into separate segments. The reactor may be a multi-bed type, for example, with mixing of streams within the reactor. It may have several mixing and feedstock feed zones. The reactor may also be tubular with catalyst contained in the reaction tubes, etc. The conversion feedstock is chosen so that exo- and endothermal reactions proceed efficiently, which affords several aforementioned advantages.

[0067] During conversion of hydrocarbons to aromatic hydrocarbon concentrate, fixed-bed reactors with periodic catalyst regeneration or fluidized-bed catalytic reactors with continuous catalyst regeneration are used.

[0068] Reactor 2 is designed for aromatization of a mixture of saturated and unsaturated aliphatic hydrocarbons and oxygenates and contains at least one hydrocarbon feedstock heater 19, at least one hydrocarbon feedstock mixer 20, and at least one reaction zone 21.

[0069] Unit 3 for separating the conversion products into reaction water, hydrogen-containing gas, stable aromatic hydrocarbon concentrate, and the natural gas liquids contains a three-phase conversion product separator for reaction water, liquid hydrocarbons, and discharge gases, as well as a module for stripping discharge gases from the three-phase separator, which permits extraction of the natural gas liquids containing olefins from the discharge gases. Unit 3 may also contain circulation compressor 14.

[0070] To maximize the AHCC yield, the discharge gas stripping module must afford extraction of 90% of the propane from the discharge gases. Deethanization of the natural gas liquids (distillation of at least part of the dissolved methane and ethane from the natural gas liquids) is desirable, since it permits reduction of the circulation of ethane and methane which are contained in the natural gas liquids and do not participate in the process.

EMBODIMENT OF THE INVENTION

[0071] Aromatic hydrocarbon production according to the invention proceeds as follows.

[0072] Step A1. The natural gas liquids or mixtures thereof with C.sub.1-C.sub.4 aliphatic alcohols are fed to reactor 1 of the installation. The preferred feedstock is a propane-butane fraction containing 70-80% propane, as well as circulating aliphatic saturated and unsaturated hydrocarbons from unit 3 and oxygenates from unit 5. The hydrocarbons are evaporated and thoroughly mixed. To increase the alkylbenzene content of the produced aromatic hydrocarbon concentrate, the benzene or benzene-toluene fraction, including that containing aliphatic hydrocarbons, may also be fed to reactor 1 (without an extractive distillation stage to remove aliphatic hydrocarbons).

[0073] Step A2. A mixture consisting of PBF or NGL hydrocarbon feedstock, recirculating olefin-containing NGL, and oxygenates is converted in reaction zone 1 in the gaseous phase. The unsaturated aliphatic hydrocarbons recycled from unit 3 are nearly completely dehydrocyclized, oxygenate vapors are totally converted, and part of the saturated aliphatic hydrocarbons, both circulating and arriving with the feedstock stream, are converted.

[0074] Step A3. The conversion product from reactor 1 is fed to reactor 2, to which oxygenates from unit 5 are also fed. In reactor 2, the incoming mixture from the output of reactor 1, which is thoroughly mixed with oxygenate vapors arriving from unit 5, undergoes gas-phase conversion. To increase the concentration of alkylbenzenes in the produced aromatic hydrocarbon concentrate, the benzene or benzene-toluene fraction, including that containing aliphatic hydrocarbons, may also be fed to reactor 2 (without an extractive distillation stage to remove aliphatic hydrocarbons).

[0075] Step A4. Additionally, with the aid of hydrocarbon and liquid condenser 10, where the liquid part of the conversion product (C.sub.5+ and reaction water) condenses, and with the aid of separator 11, the gaseous part of the product is fed to reactor 2, while the liquid part of the product is removed and fed immediately to unit 3. The presence of condenser 10 and separator 11 permits reduction of the hydrocarbon circulation because in reactor 2, the extraction of aromatic hydrocarbons creates more favorable conditions for synthesis of aromatic hydrocarbons, which reduces recycling of the olefin-containing fraction to reactor 1.

[0076] Step A5. The conversion product from reactor 2 is fed through hydrocarbon and water condenser 13 in a mixture with hydrocarbon condensate from unit 11 (or without mixing) to unit 3. There, it is separated into reaction water to be recycled and unstable hydrocarbon condensate entering separation unit 22, where the latter is separated into a C.sub.5+ or C.sub.6+ hydrocarbon fraction and C.sub.2-C.sub.5 natural gas liquids. The discharge gases, with the aid of module 4, are separated into hydrogen-containing gas, which is fed to unit 5 for conversion to oxygenates, and the natural gas liquids containing olefins, which together with the natural gas liquids from separation unit 22 are recycled to reactor 1. The ratio of the circulating natural gas liquids from reactor 2 to the feedstock ranges from 0.3:1 to 1:1, depending on the composition of the feedstock. The ratio of oxygenates to the hydrocarbon feedstock is 1:1-1:4.

[0077] Step A6. The temperature at the outlet of each reaction zone in reactors 1 and 2 is controlled by the oxygenate flow rate. The pressure in the reaction zones is 0.5-2.5 MPa. Temperatures are from 400 C. to 520 C. Thermostabilization of the reaction zone of reactor 2 is fully or partially effected by the heat capacity of the conversion feedstock and the presence in the conversion mixture of oxygenates, whose conversion to aromatic hydrocarbons and methylbenzenes or alkylbenzenes releases heat, and paraffins, whose conversion to aromatic hydrocarbons consumes heat.

[0078] The oxygenates are distributed between reaction zones 1 and 2 so as to ensure adiabatic heating of the feedstock in the reaction zone of reactor 1 to 400-500 C. and in the second to 450-520 C., respectively, and excess oxygenates from unit 5 can be discarded.

[0079] In reactors 1 and 2, endothermal reactions of saturated aliphatic hydrocarbon conversion to aromatic hydrocarbon concentrate, exothermal reactions of oxygenate aromatization, and exothermal reactions of aromatic compound alkylation occur. As a result, adiabatic conditions can be maintained in each reaction zone of reactors 1 and 2, which permits simple reactor equipment to be used, even without the use of additional heat supply/removal from the reaction zone.

[0080] The figure additionally designates the following channels: [0081] 23: feedstock feed to reactor 1; [0082] 24: conversion output from reactor 1; [0083] 25: connection of the output of oxygenate synthesis unit 5 to the input of first reactor 1 for oxygenate feed; [0084] 26: connection of the output of unit 4 to the input of first reactor 1 for NGL feed; [0085] 27: connection of unit 11 to the input of separation unit 3 for water-hydrocarbon condensate feed; [0086] 28: connection of the output of unit 9 to the input of second reactor 2 for discharge gas feed; [0087] 29: connection of the output of oxygenate synthesis unit 5 to the input of second reactor 2 for oxygenate feed; [0088] 30: connection of the output of unit 13 to the input of separation unit 3 for conversion product and condensate feed; [0089] 31: removal of reaction water from separation unit 3; [0090] 32: boiler-quality water feed to the input of oxygenate synthesis unit 5; [0091] 33: oxygen feed to the input of oxygenate synthesis unit 5; [0092] 34: output from unit 4 to the connection unit from streams 35 for NGL feed from discharge gases; [0093] 35: connection of the output from separation unit 22 to channel 34-26 for arene concentrate stabilization gas feed; [0094] 36: output from oxygenate synthesis unit 5 for hydrogen containing gas (HCG) purge feed; [0095] 37: condensation water feed to the input of oxygenate synthesis unit 5; [0096] 38: HCG feed from unit 4 to unit 5; [0097] 39: arene concentrate stabilization gas feed from unit 3 to unit 15.

[0098] The sequence of steps is illustrative and permits some operations to be reordered, added, or performed simultaneously without loss of the capability of producing aromatic hydrocarbon concentrate from natural gas liquids.

INDUSTRIAL APPLICABILITY

[0099] The claimed installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons may be embodied in practice, and when embodied it affords realization of the claimed purpose, which supports the conclusion that the invention meets the industrial applicability criterion.

[0100] In accordance with the claimed invention, calculations of the method of operation of the installation for producing aromatic hydrocarbon concentrate from light aliphatic hydrocarbons have been performed with the following process parameters: pressure 0.5-1.5 MPa; temperature according to specification; rate of oxygenate feed to reaction zones W=1 to 2 h.sup.1 (in liquid); rate of aliphatic hydrocarbon feed to reaction zones W=200 to 1500 h.sup.1 (in gas).

[0101] According to the technological process modeling data, the process claimed in this invention is highly efficient, permitting production of up to 820 kg of aromatic hydrocarbons from a metric ton of liquefied hydrocarbon gases containing 80% propane, and up to 900 kg of aromatic hydrocarbons from a metric ton of butanes, exceeding the stated parameters for processes for producing aromatic hydrocarbons by catalytic reforming of naphtha (accounting for the recycling of aliphatic hydrocarbons separated from the reformate to the reforming stage, the aromatic hydrocarbon yield is no more than 75% of the feedstock) and by Cyclar technology (a joint development of BP and UOP), the aromatic hydrocarbon yield is up to 66% from n-butane, and no more than 60% from propane, and the AHCC yield is 53% according to data presented in the prototype specification.

[0102] Another distinguishing feature of the process is the increased yield of alkylbenzenes, in particular xylenes, which permits the use of the resulting aromatic hydrocarbon concentrate to produce xylenes, in particular paraxylene. The product made using Cyclar technology contains 20-23% xylenes, and a similar concentration is claimed in the specification of the invention prototype.

[0103] The advantages of the technological solution are: [0104] high aromatic hydrocarbon yield, 82-90%; [0105] elevated content of alkylbenzenes, including xylenes, in the aromatic hydrocarbon concentrate, 40%; [0106] simplified reactor equipment design due to the offsetting thermal effect in conversion of hydrocarbon mixtures. This solution permits use of a simple reactor for conversion, avoidance of local superheating of the catalyst, and stabilization of the catalyst's productivity across its bed, which reduces the volume of the reaction zone; [0107] possibility of separating high-added-value byproducts, for example paraxylene, from the synthesis products; [0108] low aliphatic hydrocarbon content in the aromatic hydrocarbon concentrate, 1% for conversion of propane-butane fractions; [0109] possibility of involving benzene fractions (including mixtures containing aliphatics) in the process for further conversion to alkylbenzenes; [0110] possibility of recycling discharge hydrogen-containing gas from other processes, including processes of refining aromatic hydrocarbon concentrate to marketable aromatic hydrocarbons; [0111] possibility of adjusting the oxygenate feed to reactors 1 and 2 to maintain the required process temperature; [0112] possibility of using oxygenates for co-conversion; [0113] possibility of reducing the propane conversion temperature by at least 15 C.; [0114] reduction in naphthalene content in the conversion product compared to the option of converting C.sub.3-C.sub.4 paraffins alone; [0115] two- to three-fold increase in time between regenerations compared to conversion of C.sub.3-C.sub.5 paraffins alone.

[0116] Additional technical results are: [0117] recycling of discharge gases from synthesis of arenes; [0118] stabilization of the yield of aromatic hydrocarbon concentrate in case of variation in feedstock composition and catalyst deactivation; [0119] increased aromatic hydrocarbon concentrate yield; [0120] simplification of reactor equipment design; [0121] reduction in energy costs due to reduction in circulation of aliphatic hydrocarbons from feedstock and conversion product; [0122] improved efficiency in the use of discharge gases from neighboring and main processes to increase the marketable product yield; [0123] diversification of feedstock: transition from expensive feedstock (naphtha) to cheaper feedstock (NGL).

[0124] Thus, this invention achieves its stated objective of improving the efficiency of aromatic hydrocarbon concentrate production and increasing selectivity with respect to alkylbenzenes, in particular xylenes.

[0125] The distinguishing features and advantages of the invention also follow from the tables, which are presented below for illustration and are not restrictive, in which: [0126] Table 1 tabulates a comparison of product yields; [0127] Table 2 tabulates the material and component balance of the claimed method; [0128] Table 3 tabulates data on co-aromatization of propane, n-butane, and a mixture of propane, propene, butanes, butenes, and oxygenates (methanol and isopropanol).

TABLE-US-00001 TABLE 1 Product Yield Comparison Present Prototype, Patent, Propane Conversion Conversion Conversion, of of PBF Naphtha Cyclar Butane (80% Technology Reforming Process Fraction Propane) Benzene, % 6 27 14 3 Toluene, % 21 43 45 35 Xylenes and 20 20 23 40 ethylbenzene, % Higher aromatics, 20 9 11 21 % Nonaromatic 33 1 7 1 compounds, % AHCC yield, % 78 60 53 82

TABLE-US-00002 TABLE 2 Material and Component Balance Without Use of Additional Unit 11 Stream/Unit Total, CO Ar Designation Name of From-To/ 1000 tons/ and C.sub.5+ and on Diagram Stream Remark yr CO.sub.2 H.sub.2O Methanol H.sub.2 C.sub.1-C.sub.2 C.sub.3-C.sub.4 Aliphatics Aromatics N.sub.2 O.sub.2 Reactor 1 Reactor 1 Entered reactor 1025 1 20 279 0 38 683 0 3 0 0 1, total: 23 PBF Feed- 500 0 0 0 0 10 490 0 0 0 0 stock 25 Oxygenates From 299 1 19 279 0 0 0 0 0 0 0 unit 5 26 NGL From 225 0 1 0 0 28 193 0 3 0 0 unit 3 Including: 34 NGL from From 173 0 1 0 0 21 148 0 3 0 0 discharge gases unit 3 35 Arene From 53 0 0 0 0 7 45 0 0 0 0 concentrate unit 3 stabilization gases Reactor 1 Received from 1025 1 177 0 15 120 497 3 213 0 0 reactor 1, total 24 Conversion To unit 1025 1 177 0 15 120 497 3 213 0 0 product from 9 reactor 1 Unit 9 Unit 9 Entered unit 5, 1025 1 177 0 15 120 497 3 213 0 0 total: 24 Conversion To unit 1025 1 177 0 15 120 497 3 213 0 0 product from 9 reactor 1 Unit 9 Received from 1025 1 177 0 15 120 497 3 213 0 0 unit 5, total: 27 Water-hydrocarbon To unit 455 0 175 0 0 3 68 2 207 0 0 (HC) 3 condensate 28 Discharge gases To unit 570 1 2 0 15 117 428 1 6 0 0 2 Reactor 2 Reactor 2 Entered reactor 814 2 17 229 15 117 428 1 6 0 0 2, total: 29 Oxygenates From 245 1 15 229 0 0 0 0 0 0 0 unit 5 28 Discharge gases From 570 1 2 0 15 117 428 1 6 0 0 unit 9 Reactor 2 Received from 814 2 145 0 22 251 219 2 173 0 0 reactor 2, total: Conversion To unit 814 2 145 0 22 251 219 2 173 0 0 product from 13 reactor 2 Unit 3 Unit 3 Entered unit 3, 1270 2 320 0 22 254 288 4 380 0 0 total 27 Water-hydrocarbon From 455 0 175 0 0 3 68 2 207 0 0 condensate unit 9 30 Conversion From 814 2 145 0 22 251 219 2 173 0 0 product and unit 13 condensate thereof Unit 3 Received from 1270 2 320 0 22 254 288 4 380 0 0 unit 3, total 96 Hydrogen- To unit 313 1 0 0 22 226 63 0 0 0 0 containing gas 5 34 + 35 NGL To 225 0 1 0 0 28 193 0 3 0 0 total reactor 1 31 Reaction water Product 320 0 320 0 0 0 0 0 0 0 0 39 Stabilized arene Product 411 0 0 0 0 0 30 3 377 0 0 concentrate or to unit 15 Unit 5 Unit 5 Entered unit 5, 786 1 210 0 22 226 63 0 0 2 261 total 32 Boiler-quality Feed- 210 0 210 0 0 0 0 0 0 0 0 water stock 33 Oxygen Feed- 263 0 0 0 0 0 0 0 0 2 261 stock 38 HCG From 313 1 0 0 22 226 63 0 0 0 0 unit 3 Unit 5 Received from 787 29 197 510 11 39 0 0 0 2 0 unit 4, total 37 Condensation Product 163 0 163 0 0 0 0 0 0 0 0 water 25 + 29 total Oxygenates To 544 1 34 508 0 1 0 0 0 0 0 reactors 1 and 2 36 HCG discharge Product 80 28 0 2 11 38 0 0 0 2 0 Installation As a Whole Total feedstock 973 0 210 0 0 10 490 0 0 2 261 23 PBF Feed- 500 0 0 0 0 10 490 0 0 0 0 stock 32 Boiler-quality Feed- 210 0 210 0 0 0 0 0 0 0 0 water stock 33 Oxygen 99% Feed- 263 0 0 0 0 0 0 0 0 2 261 stock Total products 973 28 482 2 11 38 30 3 377 2 0 31 Reaction water Product 320 0 320 0 0 0 0 0 0 0 0 37 Condensation Product 163 0 163 0 0 0 0 0 0 0 0 water 39 Stabilized arene Product 411 0 0 0 0 0 30 3 377 0 0 concentrate 36 HCG discharge Product 80 28 0 2 11 38 0 0 0 2 0

TABLE-US-00003 TABLE 3 Data on Co-Aromatization of Propane, n-Butane, and a Mixture of Saturated and Unsaturated C.sub.3-C.sub.4 Hydrocarbons and Oxygenates Example Number 1 2 3 Temperature, C. 490 515 450 Pressure, atm. 8 8 6 Volumetric gas flow rate, hr.sup.1 300 300 1500 TAKEN (ratio, % by wt.) Propane 76.9 n-Butane 83.3 Methyl alcohol 16.7 23.1 Isopropyl alcohol 26.5 NGL (C.sub.3-C.sub.4 fraction, 50% olefins by wt.) 73.5 TOTAL: 100 100 100 Oxygenate conversion 100 100 100 AHCC yield per feedstock pass (per HC part 44.2* 36* 78.2* of feedstock)*, % by wt. C.sub.1-C.sub.4 Hydrocarbon Composition of Gas, % by wt. CH.sub.4 11.1 28.1 6.9 C.sub.2H.sub.6 9.7 12.4 21.0 C.sub.2H.sub.4 5.6 6.1 3.3 C.sub.3H.sub.8 38.7 24.1 32.4 C.sub.3H.sub.6 5.1 8 4.5 i-C.sub.4H.sub.10 3.8 7.9 10.6 n-C.sub.4H.sub.10 25.1 12.6 18.5 C.sub.4H.sub.8 0.9 0.8 2.7 Total, % by wt. 100 100 100 AHCC Composition, % by wt. Aliphatics 1.3 0.9 8.2 Benzene 2.1 3.6 6.1 Toluene 32.4 36.3 32.2 Xylenes + ethylbenzene 42.1 38.7 36.4 C.sub.9+ alkylaromatics 22.1 20.4 18.1 Total aromatic HC in AHCC 98.7 99 92.8