CN109401781B

CN109401781B - Naphtha and light hydrocarbon modification method

Info

Publication number: CN109401781B
Application number: CN201710702720.6A
Authority: CN
Inventors: 任坚强; 于中伟; 王子健; 马爱增; 王杰广; 张新宽; 刘洪全; 马冲; 马云超
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-08-16
Filing date: 2017-08-16
Publication date: 2021-09-07
Anticipated expiration: 2037-08-16
Also published as: CN109401781A

Abstract

The invention relates to a naphtha and light hydrocarbon modifying method, which comprises the following steps: contacting naphtha with a dehydrogenation catalyst through a first reaction zone and carrying out dehydrogenation reaction under dehydrogenation reaction conditions to convert part of naphthenes in the naphtha into aromatic hydrocarbons; wherein the dehydrogenation catalyst comprises a first carrier and chlorine and a group VIII metal supported on the first carrier; and mixing the reaction product obtained in the first reaction zone with light hydrocarbon, then passing through the second reaction zone to contact with a modified catalyst for modification reaction, cooling and separating the obtained reaction product to obtain a gas-phase product and a liquid-phase product. The staged modification method provided by the invention can improve the yield of liquid products.

Description

Naphtha and light hydrocarbon modification method

Technical Field

The invention relates to a method for modifying naphtha and light hydrocarbon, in particular to a method for modifying through two-stage reaction.

Background

With the upgrading of environmental protection requirements and the coming of new gasoline standards, a proper processing technology is urgently needed to be found for part of low-octane gasoline, such as light naphtha of reformed topping oil, condensate oil, part of hydrogenated coker gasoline, straight-run gasoline and the like. Although this naphtha fraction is suitable as an ethylene feedstock, it is difficult to transport it due to its high vapor pressure and difficult to use in ethylene production without an ethylene plant near the business. At present, a main device for producing aromatic hydrocarbon and high-octane gasoline blending components by oil refining enterprises is catalytic reforming, reformed gasoline is used as the gasoline blending component, has the characteristics of high octane number and high liquid product yield, but has high aromatic hydrocarbon content, and cannot be called as high-quality gasoline blending component under the condition of environmental protection upgrading.

At the end of the 70's of the 20 th century, due to the discovery of ZSM-5 shape-selective molecular sieves, naphtha and/or low-carbon hydrocarbons, mainly C, can be treated under the conditions of non-hydrogenation and no use of noble metal catalysts₅The following hydrocarbons are converted into low-sulfur low-olefin gasoline components containing aromatic hydrocarbon, and at the same time a high-quality liquefied gas is produced as a by-product, and the mixed aromatic hydrocarbon in its main product is an important chemical raw material, and can be mixed and blended with other gasoline components to raise gasoline octane number, so that said technology is called aromatization modification technology. The technology has strong adaptability of raw materials, low requirements on the impurity content, the potential content and the distillation range of the raw materials, low investment on equipment and low energy consumption, and can be operated under low pressure without hydrogen in a reaction system, thereby opening up an effective way for the utilization of naphtha and low-carbon hydrocarbons in refineries.

Chinese patents CN1063121A and CN1080313A both disclose a catalyst and a process method for aromatization modification of low-octane inferior gasoline such as oil field condensate, straight-run gasoline and coker gasoline, wherein the low-octane inferior gasoline can be converted into high-octane gasoline with the octane number of about 90 by using the modified ZSM-5 molecular sieve catalyst, the gasoline yield is 55-65%, and meanwhile, 35-45% of liquefied petroleum gas and fuel gas are byproducts.

Chinese patent CN1251123A discloses a process for reforming a naphtha-containing hydrocarbon feedstock containing at least about 25 wt.% C₅To C₉Naphtha of aliphatic and cycloaliphatic hydrocarbons is contacted with a modified reforming catalyst, for example ZSM-5 containing a dehydrogenation metal selected from the group consisting of gallium, zinc, indium, iron, tin and boron, which catalyst has been modified by neutralizing at least a portion of the surface acid sites present on the catalyst by contact with a sufficient amount of a group IIA alkaline earth metal, such as barium, or with a sufficient amount of an organosilicon compound. C of the resulting reformate₁To C₄Relatively low gas yield, C₈The content of paraxylene in aromatic hydrocarbon fraction is relatively increased.

US4190519 discloses a combined process for upgrading naphtha by fractionation to obtain C-containing naphtha₆Light naphtha of alkanes and a heavier fraction containing methylcyclopentane; the heavier naphtha fraction is contacted with a modified ZSM-5 catalyst to react under the non-hydrogen condition to generate a reformate rich in aromatic hydrocarbon; the reformed product is fractionated into a light component and a heavy component, the heavy component is used for recovering aromatic hydrocarbon, and the light component and light naphtha are subjected to aromatization modification by using a ZSM-5 catalyst under a non-hydrogenation condition to obtain a high-octane gasoline component.

Chinese patent CN1651141A discloses a preparation method of a pellet catalyst suitable for moving bed technology and a moving bed aromatization modification technology of inferior gasoline, by which naphtha can be modified into high octane gasoline, and the gasoline yield is obviously improved compared with the fixed bed aromatization modification technology.

Chinese patent CN101875851A discloses a non-hydrogenation modification method of liquefied gas fraction, which comprises dividing raw materials of liquefied gas fraction into multiple strands, respectively entering into multiple series-connected modification reaction zones, contacting with modification catalyst to generate olefin polymerization, isomerization and aromatization reaction, separating reaction products to obtain liquefied gas blending components for vehicles and gasoline blending components, and circulating part of gas phase product flow to the reaction zones.

Chinese patent CN101429452A discloses a method for producing high octane gasoline by contacting catalytic cracking gasoline and C4 mixed raw material with catalyst on aromatization reactor, the catalytic cracking gasoline and C4 olefin are mixed, and enter into fixed bed or simulated moving bed aromatization reactor filled with molecular sieve catalyst, and contact with aromatization catalyst to make olefin aromatization reaction, its reaction condition is: the reaction temperature is 250-340 ℃, the pressure is 0.5-3.0 MPa, and the weight space velocity is 0.5-10 h^-1The mass ratio of the C4 olefin to the catalytic cracking gasoline is 90: 10-2: 98; the carrier molecular sieve active component of the catalyst is one or more of rare earth elements, VIB and VIII family elements, and the weight of the active component is 0.01-10% of that of the carrier; can obviously reduce the olefin content of the raw material gasoline, effectively improve the octane number and achieve the aim of producing high-octane clean gasoline.

Chinese patent CN101747933A discloses an aromatization modification method of naphtha and light hydrocarbon, which comprises the step of contacting naphtha and light hydrocarbon of C3-C5 with an aromatization catalyst in a moving bed reaction zone of a moving bed reaction-regeneration device in the presence of hydrogen-containing gas to carry out aromatization modification reaction, wherein the modification reaction temperature is 250-600 ℃, and the volume ratio of hydrogen to naphtha is 20-400. The method can convert naphtha with low octane number and low carbon hydrocarbon into gasoline component with high octane number and high-quality liquefied gas, the final boiling point of the liquid product and the carbon deposition rate of the catalyst are obviously reduced, and the service life of the catalyst is prolonged.

Chinese patent CN1600836A discloses a method for preparing gasoline with low olefin content by modifying straight-run gasoline, which comprises the steps of mixing the straight-run gasoline with carbon tetraolefin fraction, carrying out contact reaction with a catalyst containing HZSM-5 under the conditions of 0.2-0.6 MPa and 300-500 ℃, and then separating dry gas, liquefied gas and gasoline components in the product. The method can effectively utilize four carbon components in a refinery to modify the straight-run gasoline and produce gasoline components with high octane value and low olefin content.

Chinese patent CN101397510A discloses a process for upgrading poor gasoline, which comprises introducing the poor gasoline blended with four carbon cuts as reaction raw material into a reactor, contacting with catalyst under non-hydrogen condition for reaction, wherein the four carbon cuts are divided into multiple strands, the first strand is mixed with the poor gasoline and then enters the reactor, and the other strands enter the reactor from different parts, the process can reduce the temperature rise of the reactor, increase the blending ratio of the four carbon cuts and the gasoline yield of the upgraded product, and prolong the service life of the catalyst.

Disclosure of Invention

The invention aims to provide a naphtha and light hydrocarbon modifying method, which can improve the yield of liquid products.

In order to achieve the above object, the present invention provides a method for upgrading naphtha and light hydrocarbons, comprising: contacting naphtha with a dehydrogenation catalyst through a first reaction zone and carrying out dehydrogenation reaction under dehydrogenation reaction conditions to convert part of naphthenes in the naphtha into aromatic hydrocarbons; wherein the dehydrogenation catalyst comprises a first carrier and chlorine and a group VIII metal supported on the first carrier; and mixing the reaction product obtained in the first reaction zone with light hydrocarbon, then passing through the second reaction zone to contact with a modified catalyst for modification reaction, cooling and separating the obtained reaction product to obtain a gas-phase product and a liquid-phase product.

The modified gasoline produced by the method is a high-quality gasoline blending component, and meanwhile, a high-quality liquefied gas component is produced as a byproduct, compared with the traditional naphtha or naphtha and light hydrocarbon aromatization modification process, the octane number and the yield of the high-quality gasoline blending component are greatly improved, and compared with the naphtha catalytic reforming process, the aromatic hydrocarbon content of a liquid product, the investment of a production device and the energy consumption are obviously reduced.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic flow diagram of one embodiment of the upgrading process provided by the present invention.

Description of the reference numerals

1 pipeline 2 heat exchanger 3 heating furnace

4 fixed bed reactor 5 heating furnace 6 fixed bed reactor

7 cooler 8 gas-liquid separator 9 gas compressor

10 product work-up unit 11 line 12 line

13 line 14 line 15 line

16 line 17 line 18 line

19 line 20 line 21 line

22 line 23 line 24 line

25 line 26 line 27 heat exchanger

28 line 29 line 30 line

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

According to the naphtha and light hydrocarbon modification method, after the naphtha is subjected to dehydrogenation reaction in the first reaction zone, the reaction product and the light hydrocarbon are mixed and sent into the second reaction zone for modification reaction, and the yield of liquid products in the obtained products is high.

The naphtha is subjected to dehydrogenation reaction in advance, so that part of naphthenes in the naphtha are converted into aromatic hydrocarbons, thereby increasing the aromatic hydrocarbon content and octane number of a modified liquid product, simultaneously reducing the cracking of the naphthenes in the raw oil in the modification reaction process of a second reaction zone, and effectively improving the selectivity and the liquid product yield of the naphtha modification process.

The first reaction zone and the second reaction zone are connected in series and may be separate fixed bed reactors or fixed bed layers in reactors, for example, the first reaction zone and the second reaction zone each comprise one or more fixed bed reactors; or according to the flow direction of the reaction materials, the first reaction zone is one or more catalyst beds in an independent fixed bed reactor, and the second reaction zone is one or more catalyst beds in the independent fixed bed reactor.

Preferably, the loading of the dehydrogenation catalyst in both reaction zones is from 5 to 50 mass%, more preferably from 10 to 30 mass%, based on the total loading of the catalyst.

Due to the limited aromatics content in gasoline, it is desirable to convert naphthenes to aromatics in an amount appropriate to convert preferably 25-50 mass% of the naphthenes in naphtha to aromatics in the first reaction zone. The control method comprises the steps of detecting the composition of a reaction product in the first reaction zone, determining the conversion condition of naphthenes into aromatic hydrocarbons by comparing the contents of naphthenes and aromatic hydrocarbons in a liquid product with the composition of naphtha, and controlling the ratio of the dehydrogenation conversion of naphthenes into aromatic hydrocarbons by adjusting the reaction temperature in the first reaction zone.

And the reaction product in the second reaction zone is subjected to heat exchange and cooling with naphtha and light hydrocarbon and then is separated into a gas-phase product and a liquid-phase product, at least part of the gas-phase product can be returned to the first reaction zone, and the liquid-phase product and the rest of the gas-phase product enter a product post-treatment unit for absorption, analysis, stabilization and other process steps, so that a high-quality gasoline blending component and a high-quality liquefied gas component are obtained. The gas phase product in the invention is a mixed gas of hydrogen and low-carbon hydrocarbon, and can be divided into dry gas and liquefied gas, wherein the main components of the dry gas are hydrogen and C₁、C₂The hydrocarbon, the component of the liquefied gas being C₃、C₄A hydrocarbon. Part of the gas phase product returns to the first reaction zone and mainly serves as a diluting and transferring medium, and the contained hydrogen can reduce the carbon deposition rate of the dehydrogenation catalyst; when in useAfter part of the gas-phase products returning to the first reaction zone enter the second reaction zone, the gas-phase products are used as a medium for dilution and transmission, which is beneficial to reducing the side reaction effect in the modification process and improving the selectivity of the modification reaction, and the contained liquefied gas component can continue to participate in the modification reaction, thereby being beneficial to improving the octane number and the yield of the liquid product. In the present invention, it is preferred to return 30 to 90% by volume of the gas-phase product to the first reaction zone, and it is more preferred to return 60 to 80% by volume of the gas-phase product to the first reaction zone.

In the invention, the first reaction zone adopts reaction conditions favorable for dehydrogenation of cycloalkane, and the reaction temperature can be 360-480 ℃, and is preferably 380-440 ℃; the reaction pressure may be from 0.1 to 1.0MPa, preferably from 0.3 to 0.6 MPa; the feeding mass space velocity of the naphtha can be 2-20h^-1Preferably 4-10h^-1(ii) a The volume ratio of the gas phase product returned to the first reaction zone to the naphtha feed is 100-1000, preferably 200-800.

In the invention, the reaction product in the first reaction zone and the light hydrocarbon are mixed and then enter the second reaction zone to be in contact reaction with the modification catalyst under the modification reaction condition, a part of the light hydrocarbon is converted into a liquid product, the octane number and the yield of the liquid product are further improved through aromatization, isomerization, alkylation and other reactions, and the product selectivity and the overall reaction effect in the modification process are obviously improved. The second reaction zone adopts aromatization modification reaction conditions, and the reaction temperature can be 220-460 ℃, preferably 240-420 ℃; the reaction pressure is 0.1-1.0MPa, preferably 0.3-0.6 MPa; the total feeding mass space velocity of naphtha and light hydrocarbon is 0.2-5.0h^-1Preferably 0.4-1.5h^-1。

The naphtha of the invention has an initial boiling point of 40-90 ℃, an end boiling point of 120-210 ℃, and C content₅～C₁₂The hydrocarbon fraction of (a) may be at least one selected from the group consisting of straight run gasoline, hydrocracked gasoline, catalytically cracked gasoline, hydrocracked gasoline, reformed topped oil, reformed raffinate oil, condensate oil, pyrolysis gasoline and pyrolysis gasoline raffinate oil. The naphtha naphthene content may be 15 to 50 mass%, preferably 20 to 40 mass%. The naphtha can be subjected to conventional pre-hydrofining for removing impurities such as sulfur, nitrogen and heavy metals, or subjected to light-degree hydrofiningWith or without any pre-refining treatment, the sulfur content is not more than 200. mu.g/g, preferably not more than 160. mu.g/g, the nitrogen content is not more than 5. mu.g/g, preferably not more than 2. mu.g/g. The proportion of the naphtha to the total mass of naphtha and light hydrocarbon may be 40 to 90%, preferably 50 to 80%.

The light hydrocarbon of the invention contains C₂～C₅The hydrocarbon can be liquefied petroleum gas and dry gas from processing processes of catalytic cracking, hydrocracking, thermal cracking, coking and the like in an oil refinery, for example, at least one of catalytic cracking dry gas, catalytic cracking liquefied petroleum gas, hydrocracking dry gas, hydrocracking liquefied petroleum gas, thermal cracking dry gas, thermal cracking liquefied petroleum gas, coking dry gas and coking liquefied petroleum gas, the olefin content of light hydrocarbon can be 10-90 mass%, preferably 30-80 mass%, and the sulfur content is not more than 200 mug/g. The liquefied petroleum gas may be a liquefied petroleum gas fraction remaining after separation of propylene, isobutylene, isobutane and the like.

The dehydrogenation catalyst of the present invention has a dehydrogenation function, and comprises a first carrier and chlorine element and a group VIII metal supported on the first carrier, the dehydrogenation catalyst preferably comprises 0.05 to 1 mass% of the group VIII metal and 0.1 to 5.0 mass% of chlorine, the group VIII metal content is preferably 0.3 to 0.8 mass%, the chlorine content is preferably 0.6 to 1.2 mass%, and the group VIII metal is preferably platinum, based on the amount of the alumina carrier dry substrate, and in this case, the dehydrogenation catalyst may also be referred to as a monoplatinum catalyst.

The reforming catalyst used in the second reaction zone of the present invention may include 0.1 to 5.0 mass% of a metal oxide, which may be at least one selected from the group consisting of zinc oxide, antimony oxide, mixed rare earth oxide, bismuth oxide, molybdenum oxide, and gallium oxide, and 95.0 to 99.9 mass% of a second support, on a dry basis, and the mixed rare earth oxide may include 20 to 40 mass% of lanthanum oxide, 40 to 60 mass% of cerium oxide, 10 to 18 mass% of praseodymium oxide, and 2 to 10 mass% of neodymium oxide. The second support may include 50 to 80 mass% of the HZSM-5 molecular sieve and 20.0 to 50.0 mass% of γ -Al on a dry basis₂O₃The silicon aluminum of the HZSM-5 molecular sieveThe ratio (silica/alumina molar ratio) may be from 30 to 200, preferably from 30 to 100. The catalyst can be formed by a conventional extruding, dropping or rolling method, and then the metal active component is introduced by an impregnation method.

Before the dehydrogenation catalyst and the modification catalyst are contacted with naphtha, the two catalysts can be dried and activated by adopting a gas medium in a reaction in situ, the activation temperature is 300-500 ℃, the preferred temperature is 400-450 ℃, the pressure is 0.1-1.0MPa, the preferred pressure is 0.3-0.5MPa, the volume ratio of the gas medium to the catalyst is 100-1000:1, and the activation time is 1-5 h. The gas medium for activating the catalyst is nitrogen or hydrogen, and the purity of the gas medium is more than 99.8 percent.

The dehydrogenation catalyst and the modification catalyst in the method can be repeatedly used through regeneration after being deactivated. The catalyst regeneration can be carried out in situ, the regeneration medium adopts oxygen-containing inert gas, the activity of the catalyst is recovered by burning off carbon deposit on the catalyst, the oxygen content of the regeneration medium is 0.5-5%, the appropriate regeneration temperature is 350-500 ℃, the pressure is 0.1-1.0MPa, and the volume ratio of the regeneration medium to the catalyst is 200-1000: 1. The regeneration mode can adopt several conventional modes of the fixed bed reactor according to actual requirements, such as intermittent reaction and regeneration of a single reaction system, or switching reaction and regeneration of a double reaction system, or adopting a cyclic regeneration mode of alternately switching regeneration of multiple reactors.

An embodiment of the present invention will now be provided with reference to the accompanying drawings, but the invention is not limited thereto.

Fig. 1 includes two fixed bed reactors 4 and 6 in series as a first reaction zone and a second reaction zone, respectively.

As shown in fig. 1, naphtha is fed into the upgrading reaction system through a pipeline 1, after heat exchange is carried out between the tube side of the heat exchanger 2 and the reaction product of the upgrading reaction from a pipeline 18 through the shell side of the heat exchanger 2, the naphtha is mixed with a part of the returned gas phase product from the pipeline 22 through a pipeline 14, and then the mixture is fed into the heating furnace 3 to be heated to the temperature required by the fixed bed reactor 4, and then the mixture is fed into the fixed bed reactor 4 through a pipeline 15 to be contacted with a dehydrogenation catalyst to carry out the dehydrogenation reaction of naphthenes, and the reaction product is discharged through a pipeline 30.

Light hydrocarbon enters the upgrading reaction system through a pipeline 29, after heat exchange is carried out between the light hydrocarbon flowing through the tube pass of the heat exchanger 27 and a reaction product of the upgrading reaction flowing through the shell pass of the heat exchanger 27 from a pipeline 28, the light hydrocarbon is mixed with the reaction product of the fixed bed reactor 4 from a pipeline 30 through a pipeline 23, the mixed product enters the heating furnace 5 through a pipeline 16 to be heated to the temperature required by the fixed bed reactor 6, the mixed product enters the fixed bed reactor 6 through a pipeline 17 to be contacted with the upgrading catalyst for upgrading reaction, and the reaction product is discharged through a pipeline 18.

The upgrading reaction product flows through the shell side of the heat exchanger 2 through a pipeline 18 to exchange heat with naphtha flowing through the tube side of the heat exchanger 2 from a pipeline 1, then flows through the shell side of the heat exchanger 27 through a pipeline 28 to exchange heat with light hydrocarbon flowing through the tube side of the heat exchanger 27 from a pipeline 29, then enters the cooler 7 through a pipeline 19 to be cooled, and enters the gas-liquid separator 8 through a pipeline 20 to be separated into a liquid phase product and a gas phase product. The gas phase product is discharged through a pipeline 21, one part of the gas phase product is compressed by a gas compressor 9 and then returns to the fixed bed reactor 4 through a pipeline 22, the other part of the gas phase product is mixed with the liquid phase product from a pipeline 25 through a pipeline 24 and then enters a product post-processing unit 10 through a pipeline 26 to carry out the process steps of absorption, analysis, stabilization and the like, the dry gas product in the modified product is sent out of the modification reaction system through a pipeline 11, the high-quality liquefied gas product is sent out of the modification reaction system through a pipeline 12, and the liquid product is sent out of the modification reaction system through a pipeline 13 as a high-quality gasoline blending component.

The invention is further illustrated below by way of examples, without being limited thereto.

The sources and properties of the mixed naphthas used in the inventive and comparative examples are shown in table 1 and the properties of the light hydrocarbons used are shown in table 2.

In the examples of the present invention and the comparative examples, the octane number yield is the liquid product yield × the liquid product octane number.

The method for calculating the relative stability of the upgrading catalyst in the examples of the invention and the comparative examples is as follows: example or comparative example catalyst one-way cycle run time/baseline catalyst one-way cycle run time (the relative stability of the upgrading catalyst of example 3 is set to 1, with the remaining examples being based on the upgrading catalyst one-way cycle run time of example 3).

The composition of the liquid product is analyzed by adopting Shimadzu GC-2010AF chromatograph under the specific analysis conditions that: carrier gas N₂Capillary quartz column, FID detector; the temperature of the sample injection splitter is 180 ℃, the initial temperature is 36 ℃, the final temperature is 200 ℃, the temperature of the gasification chamber and the detector is 180 ℃, the positions of the components are determined according to the retention time, and the content of the components is determined by adopting a normalization quantitative method.

The octane number of the liquid product was measured using a CFR-1 octane number tester from Waukesha.

In the example, the alpha value of the cracking activity measured by the n-hexane cracking reaction is used for representing the acidity of the catalyst, and the alpha value is measured by using a test method of RIPP 89-90 (constant temperature method for measuring the alpha value of the acidic catalyst), which is specifically disclosed in "petrochemical analysis method (RIPP test method)" published by scientific Press, 1990 edition, P255-256, published by Yangshui et al.

Example 1

Preparing a dehydrogenation catalyst.

Taking 100 g (95 g on a dry basis) of gamma-Al₂O₃The carrier was used as a first carrier, the saturated water absorption was measured to be 82mL, and a predetermined amount of chloroplatinic acid and hydrochloric acid was used to prepare 140mL of an impregnation solution containing 0.5 mass% of Pt and 1.9 mass% of Cl (both relative to the amount of alumina dry substrate), so that the volume ratio of the impregnation solution to the carrier was 1.05: 1. The carrier is placed in a flask, vacuum pumping is carried out, the vacuum degree is controlled to be 0.085MPa, impregnation liquid is introduced, rotary impregnation is carried out for 3 hours at the temperature of 30 ℃, the rotary linear velocity is 0.10 m/s, then drying is carried out under reduced pressure, and roasting is carried out for 4 hours in dry air at the temperature of 500 ℃ and the gas/solid volume ratio of 700: 1. The catalyst obtained by the above method contained 0.5 mass% of Pt and 1.0 mass% of Cl based on the amount of the alumina carrier dry substrate.

Example 2

Preparing the modifying catalyst.

(1) Preparation of the second support

Taking 120g of HZSM-5 molecular sieve powder (produced by Shanghai Huaheng chemical plant) with a silica/alumina molar ratio of 56 and 80 g of aluminum hydroxide powder (produced by Qilu catalyst plant and with an alumina content of 76 mass percent), stirring uniformly, adding 4 ml of nitric acid with a concentration of 40 mass percent and 100 ml of deionized water, kneading fully, extruding into strips with a diameter of 2 mm, drying at 110 ℃ for 8 hours, cutting into particles with a length of 2-3 mm, and roasting at 570 ℃ for 4 hours.

(2) Preparation of the catalyst

100 g of the second carrier was taken out, and the carrier was immersed in 100 ml of an aqueous solution containing 1.0 g of mixed rare earth chloride (produced by Nemontage Baotou rare earth industries, in which 31 mass% of lanthanum oxide, 51 mass% of cerium oxide, 14 mass% of praseodymium oxide, and 4 mass% of neodymium oxide in terms of oxides) at 80 ℃ for 2 hours, dried at 120 ℃ for 8 hours, and calcined at 550 ℃ for 4 hours. The prepared catalyst is loaded into a tubular reactor, the temperature is raised to 580 ℃ in air flow under normal pressure, then the steam is introduced for treatment for 5 hours under the temperature, the total water inflow is 400 g, and then dry air is introduced for blowing and cooling.

The catalyst prepared in this example contained 0.43 mass% of a mixed rare earth oxide (X-ray fluorescence analysis) on a dry basis and the balance of a second support in which 64.6 mass% of HZSM-5 molecular sieve and 35.4 mass% of γ -Al were contained₂O₃And alpha value is 30.

Example 3

Naphtha and light hydrocarbons are upgraded according to the process of the present invention.

In a laboratory fixed bed four-reactor adiabatic medium-sized test device (4 reactors of the device are arranged in series, each reactor is provided with an independent raw oil and raw material gas feeding system, the outlets of the first three reactors are provided with an online chromatograph, the composition of the product at the outlet of the reactor can be detected in real time, and the device is provided with a gas circulation compressor), the first two reactors are filled with catalysts, the total filling amount of the catalysts is 120g, wherein the first reactor is filled with 15g of the dehydrogenation catalyst prepared in the example 1, and the second reactor is filled with 105g of the upgrading catalyst prepared in the example 2.

The dehydrogenation catalyst and the modification catalyst are activated in the device before reaction, the activating medium is nitrogen, and the activation is carried out for 2 hours under the conditions that the pressure is 0.4MPa, the volume ratio of the nitrogen to the catalyst is 500:1, and the inlet temperature of the reactor is 400 ℃.

Introducing mixed naphtha shown in table 1 into a first reactor, contacting with a dehydrogenation catalyst under dehydrogenation reaction conditions, carrying out dehydrogenation reaction, controlling 35-40 mass% of naphthenes in the naphtha to be converted into aromatic hydrocarbons (detecting by an online chromatograph, and adjusting the inlet temperature of the first reactor), introducing a reaction product of the first reactor and light hydrocarbon shown in table 2 into a second reactor after mixing, contacting with a upgrading catalyst under upgrading reaction conditions, carrying out upgrading reaction, and adjusting the inlet temperature of the second reactor by taking Research Octane Number (RON)90 of a liquid product as a target. And cooling and separating the modified reaction product to obtain a gas-phase product and a liquid-phase product, returning 70 volume percent of the gas-phase product to the first reactor, and allowing the liquid-phase product and the residual gas-phase product to enter a product absorption-stabilization system to obtain a high-quality gasoline blending component as a liquid product and a high-quality liquefied gas component.

The reaction pressure of the two reaction zones is 0.4MPa, the total feeding quantity of naphtha and light hydrocarbon is 100.0g/h, and the total mass space velocity is 0.83h^-1Wherein the feeding amount of naphtha is 80.0g/h, and the space velocity of the feeding mass relative to the first reactor is 5.33h^-1The feeding amount of light hydrocarbon is 20.0g/h, and the feeding mass space velocity of naphtha and light hydrocarbon relative to the second reactor is 0.95h^-1(ii) a The initial reaction temperature of the first reactor is 380 ℃, the volume ratio of the gas-phase product returned to the first reaction zone to the naphtha feed is 400, and the initial reaction temperature of the second reactor is 280 ℃. The specific reaction results are shown in Table 3.

Example 4

Naphtha and light hydrocarbons were upgraded as in example 3, except that the ratio of the naphtha feed to the total feed was 60 mass%, i.e., the naphtha feed was 60.0g/h, and the space velocity relative to the feed mass of the dehydrogenation zone was 4.0h^-1(ii) a The proportion of the light hydrocarbon feeding amount to the total feeding amount is 40 percent by mass, namely the light hydrocarbon feeding amount is 40.0g/h, and the feeding mass space velocity of naphtha and light hydrocarbon relative to the second reactor is 0.95h^-1(ii) a The initial reaction temperature of the first reactor is 370 ℃, and the initial reaction temperature of the second reactor is 260 ℃. The specific reaction results are shown in Table 3.

Example 5

Naphtha and light hydrocarbons were upgraded as in example 3, except that the ratio of naphtha feed to total feed was 40 massThe weight percent, namely the feeding amount of naphtha is 40.0g/h, and the space velocity of the feeding mass relative to the first reactor is 2.66h^-1(ii) a The proportion of the light hydrocarbon feeding amount to the total feeding amount is 60 percent, namely the light hydrocarbon feeding amount is 60.0g/h, and the feeding mass space velocity of naphtha and light hydrocarbon relative to the second reactor is 0.95h^-1(ii) a The initial reaction temperature of the first reactor zone was 360 deg.C and the initial reaction temperature of the second reactor was 240 deg.C. The specific reaction results are shown in Table 3.

Comparative example 1

Modifying naphtha and light hydrocarbon according to a conventional non-hydrogenation modification method.

120g of the reforming catalyst prepared in example 2 was packed in the first reactor of the pilot plant of example 3.

Activating the modified catalyst in a reaction device before reaction, wherein an activating medium is nitrogen, and the activating medium is activated for 2 hours under the conditions that the pressure is 0.4MPa, the volume ratio of the nitrogen to the catalyst is 500:1, and the inlet temperature of a reactor is 400 ℃.

The mixed naphtha (in a proportion of 80 mass%) shown in table 1 and the light hydrocarbon (in a proportion of 20 mass%) shown in table 2 were uniformly mixed and introduced into a reactor, and were subjected to a contact reaction with a reforming catalyst under a reforming reaction condition, and the reactor inlet temperature was adjusted with the Research Octane Number (RON)90 of a liquid product as a target. And cooling and separating the modified reaction product to obtain a gas-phase product and a liquid-phase product, and allowing the gas-phase product and the liquid-phase product to enter a product absorption-stabilization system to obtain a gasoline blending component (liquid product) and a liquefied gas component. The modified reaction pressure is 0.4MPa, the total feeding quantity of naphtha and light hydrocarbon is 60g/h, and the mass space velocity is 0.5h^-1Initial reaction temperature 380 ℃. The specific reaction results are shown in Table 3.

As can be seen from the data of example 3 and comparative example 1 in table 3, the naphtha and light hydrocarbon modified by the method of the present invention has significantly improved liquid product yield and relative catalyst stability and significantly increased raw material throughput of the apparatus compared to the conventional non-hydroaromatization modification process of naphtha and light hydrocarbon under the condition of equivalent octane number of the liquid product. At the same time, the data of examples 3 and 5 show that too much light hydrocarbon incorporation in the total feed results in a significant reduction in liquid product yield and catalyst relative stability.

TABLE 1

TABLE 2

Components	Content, mass%
		CH₄	0.93
C₂H₄	2.76
		C₂H₆	1.82
C₃H₆	32.64
		C₃H₈	18.65
C₄H₈	26.62
		C₄H₁₀	12.82
＞C₅	3.76
		Sulfur content μ g/g	182

TABLE 3

Example number	3	4	5	Comparative example 1
					Initial reaction temperature of the first reactor, deg.C	380	370	360	-
Initial reaction temperature of the second reactor, DEG C	280	260	240	380
					Reaction pressure, MPa	0.4	0.4	0.4	0.4
Total feed mass airspeed, h^-1	0.83	0.83	0.83	0.5
					Feed amount of naphtha in g/h	80.0	60.0	40.0	48.0
Light hydrocarbon feed rate, g/h	20.0	40.0	60.0	12.0
					Yield of liquid product, mass%	79.32	75.16	66.23	58.65
Octane number of liquid product (RON)	90.2	90.1	90.1	90.1
					Octane number yield, mass%	71.5	67.7	59.7	52.8
Aromatic content in liquid product, mass%	29.65	28.33	27.68	27.56
					Sulfur content of liquid product, μ g/g	＜1	＜1	＜1	9.6
Nitrogen content of liquid product, mu g/g	＜1	＜1	＜1	＜1
					Relative stability of upgrading catalyst	1.0	0.91	0.56	0.28

Claims

1. A process for upgrading naphtha and light hydrocarbons comprising:

contacting naphtha with a dehydrogenation catalyst through a first reaction zone and carrying out dehydrogenation reaction under dehydrogenation reaction conditions, so that 25-50 mass% of naphthenes in the naphtha are converted into aromatic hydrocarbons; wherein, the dehydrogenation catalyst comprises an alumina carrier and a catalyst supported on the alumina carrier0.05-1 mass% of platinum and 0.1-5.0 mass% of chlorine, based on the amount of the alumina carrier dry substrate; the dehydrogenation reaction conditions include: the reaction temperature is 360-480 ℃, and the feeding mass space velocity of naphtha is 2-20h^-1；

Mixing the reaction product obtained in the first reaction zone with light hydrocarbon, then passing through the second reaction zone to contact with a modified catalyst for modification reaction to produce modified gasoline, and cooling and separating the obtained reaction product to obtain a gas-phase product and a liquid-phase product;

the light hydrocarbon contains C2-C5 hydrocarbons, wherein the content of olefin is 10-80 mass%, and the content of alkane is 15-50 mass%; at least a portion of the gas phase product is returned to the first reaction zone.

2. The process of claim 1, wherein the first and second reaction zones each comprise one or more fixed bed reactors; or

According to the flow direction of reaction materials, the first reaction zone is one or more catalyst beds in an independent fixed bed reactor, and the second reaction zone is one or more catalyst beds in the independent fixed bed reactor.

3. The process of claim 1, wherein the dehydrogenation catalyst loading in both reaction zones is from 5 to 50 mass% of the total catalyst loading.

4. The process of claim 1 wherein the naphtha is in a proportion of 40-90% of the total mass of naphtha and light hydrocarbons.

5. The process of claim 1, wherein 30 to 90 volume percent of the gas phase product is returned to the first reaction zone.

6. The process according to claim 1, wherein the dehydrogenation reaction is carried out at a reaction pressure of 0.1 to 1.0 MPa.

7. According to claim1, wherein the upgrading reaction conditions comprise: the reaction temperature is 220-460 ℃, the reaction pressure is 0.1-1.0MPa, and the total feeding mass space velocity of naphtha and light hydrocarbon is 0.2-5.0h^-1。

8. The process as claimed in claim 1, wherein the naphtha has a initial boiling point of 40 to 90 ℃, an end point of 120 ℃ and a naphthenes content of 15 to 50% by mass, contains C5 to C12 hydrocarbons, has a sulfur content of not more than 200. mu.g/g, and has a nitrogen content of not more than 5. mu.g/g.

9. The process of claim 1, wherein the naphtha is at least one selected from the group consisting of straight run gasoline, hydrocracked gasoline, catalytically cracked gasoline, hydrocracked gasoline, reformed topped oil, reformed raffinate, condensate, pyrolysis gasoline, and pyrolysis gasoline raffinate.

10. The method of claim 1, wherein the light hydrocarbon has a sulfur content of no greater than 200 μ g/g.

11. The method of claim 1, wherein the light hydrocarbon is at least one selected from the group consisting of catalytically cracked dry gas, catalytically cracked liquefied petroleum gas, hydrocracked dry gas, hydrocracked liquefied petroleum gas, thermally cracked dry gas, thermally cracked liquefied petroleum gas, coked dry gas, and coked liquefied petroleum gas.

12. The process according to claim 1, wherein the upgrading catalyst comprises 0.1 to 5.0 mass% of the metal oxide and 95.0 to 99.9 mass% of the second support on a dry basis.

13. The method according to claim 12, wherein the metal oxide is at least one selected from the group consisting of zinc oxide, antimony oxide, mixed rare earth oxide including 20-40 mass% of lanthanum oxide, 40-60 mass% of cerium oxide, 10-18 mass% of praseodymium oxide, and 2-10 mass% of neodymium oxide, bismuth oxide, molybdenum oxide, and gallium oxide;

the second carrier comprises 50-80% of HZSM-5 molecular sieve and 20.0-50.0% of gamma-Al by mass on a dry basis₂O₃The HZSM-5 molecular sieve has a silica/alumina molar ratio of 30-200.