CN112694912B

CN112694912B - Naphtha modification method

Info

Publication number: CN112694912B
Application number: CN201911007528.0A
Authority: CN
Inventors: 任坚强; 于中伟; 王子健; 马爱增; 王杰广; 张新宽; 马冲; 马云超; 董晨; 刘彤
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: 2019-10-22
Filing date: 2019-10-22
Publication date: 2022-12-13
Anticipated expiration: 2039-10-22
Also published as: CN112694912A

Abstract

A naphtha upgrading method comprises the steps of introducing a naphtha raw material into a dehydrogenation reaction zone and an upgrading reaction zone which are arranged in series, and enabling the naphtha raw material to contact with a dehydrogenation catalyst in the dehydrogenation reaction zone under dehydrogenation reaction conditions; when the activity of the upgrading catalyst is reduced, stopping introducing the naphtha raw material, activating the upgrading catalyst under the condition of maintaining circulation of circulating gas, wherein the activation temperature is increased by 0-50 ℃ compared with the upgrading reaction temperature when the naphtha raw material is stopped, and continuously introducing the naphtha raw material for reaction after the upgrading catalyst is activated. The method disclosed by the invention can prolong the one-way operation period of the combined process of dehydrogenation and modification of the feldspar naphtha raw material and the service life of the catalyst, and improve the yield and octane number of the liquid product.

Description

Naphtha modification method

Technical Field

The invention relates to a naphtha upgrading method, in particular to a method for upgrading naphtha through two-stage reaction.

Background

With the upgrading of environmental requirements and the coming of new standards of gasoline, a proper processing technology is urgently needed to be found for part of low-octane gasoline, such as light naphtha of reforming topped 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, the 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 yield of liquid products, but has higher aromatic hydrocarbon content, and cannot be called as high-quality gasoline blending components under the condition of environmental protection upgrading.

At the end of the 70's 20 th century, with the discovery of ZSM-5 molecular sieves, naphtha and/or low-carbon hydrocarbons, mainly hydrocarbons below C5, can be converted into low-sulfur low-olefin gasoline components containing aromatic hydrocarbons without hydrogen and without using noble metal catalysts, and high-quality liquefied gas is a byproduct, and mixed aromatic hydrocarbons in main products are important chemical raw materials, and can also be mixed and blended with other gasoline components to improve the octane number of gasoline, which is called aromatization modification technology. The technology has strong raw material adaptability, low requirements on the impurity content, the potential content and the distillation range of the raw materials, and meanwhile, a reaction system is not subjected to hydrogen and can be operated under low pressure, the device investment is low, and the energy consumption is low, so that an effective way for utilizing naphtha and low-carbon hydrocarbons in a refinery is opened up, but compared with a catalytic reforming process, the naphtha aromatization modification technology has two outstanding problems, namely the yield and the octane number of a liquid product are low, the one-way operation period is short, the catalyst regeneration is needed when the fixed bed process produces the gasoline for 60-80 days, and the catalyst regeneration is needed when the aromatic hydrocarbon is produced for only 15-20 days.

CN1063121A and CN1080313A both disclose the catalyst and process for aromatization modification of low-octane inferior gasoline such as condensate oil of oil field, straight-run gasoline and coker gasoline, and the modified ZSM-5 molecular sieve catalyst can be used to convert the low-octane inferior gasoline into high-octane gasoline with octane number of about 90, the gasoline yield is 55-65%, and at the same time 35-45% of liquefied petroleum gas and fuel gas are by-produced.

CN1251123A discloses a process for reforming a hydrocarbon feedstock containing naphtha, wherein naphtha containing at least about 25% by weight of C5 to C9 aliphatic and cycloaliphatic hydrocarbons is contacted with a modified reforming catalyst, for example ZSM-5 containing a dehydrogenation metal selected from 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. The yield of C1 to C4 gases in the resulting reformate is relatively low and the para-xylene content of the C8 aromatic fraction is relatively high.

US 4190519 discloses a combined process for upgrading naphtha by fractionation to obtain a light naphtha containing C6 alkanes and a heavier fraction containing methylcyclopentane; the heavier naphtha fraction is contacted with a modified ZSM-5 catalyst to react under the non-hydrogenation 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.

CN101358147A discloses a method for producing clean gasoline by naphtha modification, which comprises fractionating naphtha, separating isopentane oil and isopentane-removed oil, and carrying out non-hydrogenation modification on the isopentane-removed oil in the presence of a catalyst to produce clean gasoline and liquefied gas. The method can improve the liquid yield of the modification reaction and increase the treatment capacity of a reaction device, and particularly after the isopentane oil and the modified gasoline are blended, the liquid yield of the whole reaction is greatly improved, and the aromatic hydrocarbon content of the blended oil is greatly reduced.

CN104974790A discloses a method for producing high-octane gasoline from naphtha, which comprises: heating naphtha, introducing the heated naphtha into an adsorption separation tower filled with a molecular sieve adsorbent, adsorbing normal paraffin in the naphtha as adsorption oil, and allowing isoparaffin and aromatic hydrocarbon in the naphtha not to be adsorbed as absorption residual oil to flow out of the adsorption separation tower; after the adsorption separation tower is saturated, the adsorption separation tower is switched to a desorption process, and continuous operation is realized through alternate flow switching of two groups of adsorption separation towers; performing aromatization modification on the absorption oil containing normal paraffin, and blending the liquid product with raffinate oil obtained by absorption and separation of naphtha to obtain a high-octane gasoline blending component. Through the combination of naphtha separation and aromatization modification, the yield of high-octane gasoline can be improved, so that the utilization efficiency of naphtha resources is improved.

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 fixed bed aromatization modification technology.

CN101747933A discloses a naphtha and light hydrocarbon aromatization modification method, which comprises contacting naphtha and light hydrocarbon of C3-C5 with aromatization catalyst in the presence of hydrogen-containing gas in a moving bed reaction zone of a moving bed reaction-regeneration device to perform 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.

CN103361116A discloses a method for producing high octane number gasoline component, raw material rich in carbon four carbon five carbon six alkane is mixed with hydrogen and then enters into a reactor filled with dehydrogenation catalyst to perform high temperature alkane dehydrogenation reaction, dehydrogenation product passes through a non-condensable gas separation device and then is mixed with hydrogen and enters into a reactor filled with aromatization catalyst to perform aromatization, and the product after reaction is separated into dry gas, liquefied gas, gasoline component and diesel oil component. The patent greatly reduces the generation amount of low-carbon hydrocarbons such as C1-C4 and the like, and improves the yield of gasoline. The produced gasoline component has low olefin content, high non-benzene aromatic hydrocarbon content and high octane number, and can meet the current environmental protection requirement, and the diesel component can be directly used.

US 6190534 discloses a combined process for selective upgrading of naphtha to obtain aromatics-rich high-octane products. The naphtha is firstly contacted with a non-acidic non-molecular sieve catalyst containing platinum group metal in a dehydrogenation section under dehydrogenation conditions to react to obtain an intermediate product containing olefin; the intermediate product containing olefin is contacted with a solid acid aromatization catalyst containing platinum group metal in an aromatization section under aromatization conditions to obtain a product rich in aromatic hydrocarbon.

CN103834434A and CN103834437A both disclose a two-stage reaction process for hydroaromatization of carbon-four liquefied gas and poor gasoline in a fixed bed reactor. The reaction process mainly comprises a low-temperature aromatization reactor and an isobutane selective aromatization reactor, and can process olefins and poor gasoline in the carbon-four liquefied gas into high-octane gasoline fraction, and simultaneously process the residual isobutane-rich liquefied gas into a steam cracking material through proper deisobutanization. The two-stage reactor increases the flexibility of operation, is very favorable for ensuring the quality of high-octane gasoline products and steam cracking materials, and is favorable for reducing byproducts such as dry gas, coke and the like. Both reactors are operated in the presence of hydrogen to greatly extend the single pass cycle and overall catalyst life.

Disclosure of Invention

The invention aims to provide a naphtha upgrading method, which can prolong the one-way operation period of a combined process of dehydrogenation and upgrading of a feldspar naphtha raw material and the service life of a catalyst.

In order to achieve the purpose, the invention provides a naphtha upgrading method, which comprises the steps of introducing a naphtha raw material into a dehydrogenation reaction zone and an upgrading reaction zone which are arranged in series, enabling the naphtha raw material to be in contact with a dehydrogenation catalyst in the dehydrogenation reaction zone under dehydrogenation reaction conditions, sending an obtained dehydrogenation product into the upgrading reaction zone, being in contact with the upgrading catalyst under upgrading reaction conditions, cooling the obtained upgrading product, then carrying out gas-liquid separation, discharging a liquid-phase product out of a device, discharging a part of a gas-phase product, and returning the rest of the gas-phase product back to the dehydrogenation reaction zone to be used as a circulating gas;

and when the activity of the upgrading catalyst is reduced, stopping introducing the naphtha raw material, activating the upgrading catalyst under the condition of maintaining circulation of circulating gas, wherein the activation temperature is increased by 0-50 ℃ compared with the upgrading reaction temperature when the introduction of the naphtha raw material is stopped, and continuously introducing the naphtha raw material for reaction after the upgrading catalyst is activated.

Through the technical scheme, the method can effectively prolong the service life of the reforming catalyst in the combined process of the dehydrogenation and the reforming of the naphtha raw material, thereby prolonging the one-way operation period of a combined process device and improving the yield of liquid products and the yield of octane numbers.

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

Detailed Description

The following describes the embodiments of the present invention in detail. 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.

In the method, in the combined process of dehydrogenation and modification of the naphtha raw material, when the activity of the modification catalyst is reduced, the introduction of the naphtha raw material is stopped, the naphtha raw material is activated by properly raising the temperature under the condition of maintaining the circulation of the circulating gas, and then the naphtha is introduced for reaction again. Under the condition of ensuring the octane number of the liquid product, the method can effectively remove carbon deposition precursors generated in the modified catalyst in the reaction process, realize the activation treatment of the modified catalyst with reduced activity, improve the stability of the catalyst, prolong the service life of the catalyst, and further improve the yield of the liquid product and the yield of the octane number. Compared with the single-pass operation period of the naphtha raw material dehydrogenation and modification combined process which does not adopt the method, the method can improve the single-pass operation period of the process by 50-89%. The end of a single pass run cycle is standardized by the need for catalyst regeneration for complete deactivation of the dehydrogenation catalyst and/or upgrading catalyst.

In one embodiment, the naphtha feedstock may be fed to a plurality of fixed bed reaction zones arranged in series, and the dehydrogenation reaction zone and/or the upgrading reaction zone may be an independent fixed bed reactor or may consist of more than one fixed bed reactors connected in series. No separation unit is arranged between adjacent fixed bed reactors, and the product from the upstream fixed bed reactor directly enters the downstream adjacent fixed bed reactor.

In another embodiment, the naphtha feedstock can be fed into a fixed bed reactor, the fixed bed reactor comprises a dehydrogenation reaction zone and a upgrading reaction zone which are arranged in series, a separation unit is not arranged between the dehydrogenation reaction zone and the upgrading reaction zone, and a product mixture from the dehydrogenation reaction zone directly enters the upgrading reaction zone.

According to the present invention, when the activity of the reforming catalyst in the reforming reaction zone is decreased, the reforming catalyst is activated, and the temperature can be appropriately raised while the feed of the naphtha feedstock is stopped and the circulation of the gas-phase product is maintained. The standard for judging the activation required by the activity reduction of the modified catalyst is as follows: the octane number (RON) required is generally from 90 to 95 while maintaining the octane number required for upgrading the liquid product of the reaction at the temperature (T) of the upgrading reaction ₁ ) The initial temperature (T) of the reaction is compared ₀ ) Increasing the temperature by 10-30 ℃, namely, determining that the activity of the upgrading catalyst is reduced and activation is needed, stopping feeding naphtha raw materials, keeping circulation of circulating gas, and increasing the temperature to activate the upgrading catalyst. (T) ₁ -T ₀ ) This means that the activity of the reforming catalyst is lost, and is preferably 15 to 20 ℃. The temperature of the activation treatment is increased by 0 to 50 ℃, preferably 10 to 50 ℃, and more preferably 20 to 30 ℃ as compared with the temperature of the upgrading reaction when the introduction of the naphtha feedstock is stopped. The reforming reaction temperature and T at the time of stopping introduction of the naphtha feedstock ₁ The same is true.

According to the present invention, the time for activating the reforming catalyst may vary within a wide range, and is preferably 0.5 to 2 hours, more preferably 1.0 to 1.5 hours. Within the above range, the upgrading catalyst can be sufficiently activated, and the once-through operation cycle of the combined process of dehydrogenation and upgrading of the naphtha feedstock can be further increased.

According to the invention, the gas phase product is a mixed gas of hydrogen and low-carbon hydrocarbon and can be divided into a dry gas and a liquefied gas, wherein the main components of the dry gas are hydrogen and C ₁ -C ₂ The hydrocarbon, the component of the liquefied gas being C ₃ -C ₄ A hydrocarbon. During the dehydrogenation reaction and the modification reaction, part of gas-phase products are returned to the dehydrogenation reaction zone to be used as dilution,The transfer medium can reduce the carbon deposition rate of the dehydrogenation catalyst and the modification catalyst, simultaneously is helpful for reducing the side reaction of the modification reaction in the modification reaction zone and improving the selectivity of the modification reaction, and the contained liquefied gas component can also continue to participate in the modification reaction, thereby being helpful for improving the yield of the liquid product. In addition, in the activation process of the upgrading catalyst, the circulated gas-phase product is also helpful to decompose carbon deposition precursors on the catalyst, so as to realize the activation treatment of the catalyst. The proportion of the gaseous products returned to the dehydrogenation reaction zone relative to the total amount of gaseous products may vary within wide limits, preferably from 30 to 90% by volume, more preferably from 60 to 80% by volume. Within the range, the activation treatment of the upgrading catalyst can be effectively realized, so that the single-pass operation period of the naphtha raw material dehydrogenation and upgrading combined process and the stability of the catalyst are further improved, and the yield of liquid products and the yield of octane numbers are improved.

Dehydrogenation reactions of naphtha feedstocks according to the present invention are well known to those skilled in the art. The dehydrogenation reaction conditions may include: the temperature is 360-480 ℃, the pressure is 0.1-1MPa, and the feeding mass space velocity of naphtha raw material is 2-20h ^-1 The volume ratio of the gas-phase product returned to the dehydrogenation reaction zone to the naphtha raw material is (100-1000): 1. preferably, the temperature is 380-440 ℃, the pressure is 0.3-0.6MPa, and the mass space velocity of the naphtha raw material is 4-10h ^-1 The volume ratio of the gas-phase product returned to the dehydrogenation reaction zone to the naphtha raw material is (200-600): 1.

upgrading reactions of naphtha feedstocks according to this invention are well known to those skilled in the art. The upgrading reaction conditions may include: the temperature is 280-460 ℃, the pressure is 0.1-1MPa, and the feeding mass space velocity of naphtha raw material is 0.2-5h ^-1 . Preferably, the temperature is 300-440 ℃, the pressure is 0.3-0.6MPa, and the mass space velocity of the naphtha raw material is 0.4-1.5h ^-1 。

According to the present invention, a portion of naphthenes in a naphtha feedstock can be converted to aromatics by dehydrogenation reactions by contacting the naphtha feedstock with a dehydrogenation catalyst in a dehydrogenation reaction zone under dehydrogenation reaction conditions. On one hand, the aromatic hydrocarbon content and octane number of the modified liquid product are increased, on the other hand, the cracking of the naphthene in the naphtha raw material in the modification reaction process is reduced, and the selectivity and the liquid product yield in the naphtha modification process are effectively improved. In one embodiment, the method may further comprise: in the dehydrogenation reaction zone, 20 to 50 mass% of the naphthenes are converted into aromatics, based on the total mass of naphthenes in the naphtha feedstock. Preferably, 25 to 50 mass% of the cycloalkanes are converted to aromatics. The manner of controlling the amount of naphthenes converted is not particularly limited, and for example, the conversion of naphthenes to aromatics in a naphtha feedstock can be determined by detecting the composition of the reaction product in a dehydrogenation reaction zone, comparing the contents of naphthenes and aromatics in the liquid product with the composition of the feedstock oil, and controlling the ratio of naphthenes dehydrogenated to aromatics by adjusting the reaction temperature in the dehydrogenation reaction zone.

According to the present invention, after the activation treatment of the reforming catalyst is completed, naphtha is introduced to restart the reaction, and the temperature of the reforming reaction zone is controlled to be lower than the temperature of the reforming reaction zone when the naphtha feeding is stopped before the activation treatment. A method of implementation, the method further comprising: after the upgrading catalyst is activated, the temperature of the upgrading catalyst is reduced to be 3-10 ℃ lower than the upgrading reaction temperature when the naphtha raw material is stopped to be introduced, and then the naphtha raw material is continuously introduced for reaction.

According to the present invention, the dehydrogenation reaction zone maintains gas circulation even when the reforming catalyst in the reforming reaction zone is activated, and maintains the temperature of the dehydrogenation reaction zone constant when the naphtha feed is stopped. When the activation treatment of the upgrading catalyst in the upgrading reaction zone is finished, the naphtha is introduced again, and the reaction of the dehydrogenation and upgrading combined process is carried out again.

According to the present invention, the loading of the dehydrogenation catalyst in the dehydrogenation reaction zone may be 5 to 50 mass%, preferably 10 to 25 mass%, based on the total loading of the dehydrogenation catalyst and the reforming catalyst.

In one embodiment, before the combined dehydrogenation and upgrading process of the naphtha feedstock according to the present invention is reacted, the dehydrogenation catalyst and/or the upgrading catalyst may be first subjected to a dry dehydration activation process in situ in the reactor, which is well known to those skilled in the art. The temperature of the drying activation can be 300-500 ℃, preferably 400-450 ℃, the pressure can be 0.1-1.0MPa, preferably 0.3-0.5MPa, and the volume ratio of the gas medium to the catalyst can be (100-1000): the time for drying and activating can be 1-5h. The gas medium for drying and activating the catalyst is nitrogen and/or hydrogen, and the purity of the gas medium can be more than 99.8%.

According to the present invention, the dehydrogenation catalyst may comprise a first support and a group VIII metal in an amount of 0.05 to 1 mass% and chlorine in an amount of 0.1 to 5 mass%, based on the dry mass of the first support. Preferably, the group VIII metal in the dehydrogenation catalyst is platinum, the content of the group VIII metal is 0.3 to 0.8 mass%, and the content of chlorine is 0.6 to 1.2 mass%.

According to the present invention, the reforming catalyst may comprise 95 to 99.9 mass% of the second carrier and 0.1 to 5.0 mass% of the metal oxide; the metal oxide may be one or more selected from zinc oxide, antimony oxide, mixed rare earth oxide, bismuth oxide, molybdenum oxide and gallium oxide, wherein the mixed rare earth oxide may include 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. The second support may include 50-80 mass% of the HZSM-5 molecular sieve and 20-50 mass% of gamma-Al ₂ O ₃ The HZSM-5 molecular sieve has a silica-alumina ratio of 30 to 200, preferably 30 to 100. Preferably, the cracking activity alpha value of the modified catalyst measured by n-hexane cracking reaction is 20-70 (alpha value is measured by RIPP 89-90 (alpha value is measured by constant temperature method) test method (the specific method is shown in "petrochemical engineering analysis method (RIPP test method)" published by Yangshui et al, 1990 edition, P255-256), the dehydrogenation catalyst and the modified catalyst can be prepared by methods well known to those skilled in the art, for example, the catalyst can be formed by conventional extruding, dropping ball or rolling ball method, and then the metal active component is introduced by impregnation method.

According to the present invention, when the dehydrogenation catalyst and/or the upgrading catalyst are severely deactivated and cannot be activated by the method of the present invention any more, the activity thereof can be recovered by regeneration and reused. The catalyst regeneration can be carried out in situ, and oxygen-containing inert gas can be used as a regeneration medium to recover the activity of the catalyst by burning off carbon deposits on the catalyst. Wherein, the oxygen content of the regeneration medium can be 0.5-5%, the regeneration temperature can be 350-500 ℃, the pressure can be 0.1-1.0MPa, and the volume ratio of the regeneration medium to the catalyst can be (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 by adopting a single reaction system, or switching reaction and regeneration by adopting a double reaction system, or a cyclic regeneration mode by adopting a plurality of reactors to switch regeneration in turn.

According to the present invention, the naphtha feedstock may have a primary boiling point of 40 to 90 ℃, an end point of 120 to 210 ℃, a naphthene content of 15 to 50% by mass, preferably a naphthene content of 20 to 40% by mass, and may contain C ₅ -C ₁₂ The hydrocarbon of (1). The naphtha raw material can be subjected to conventional pre-hydrofining for removing impurities such as sulfur, nitrogen and the like, or to shallow pre-refining treatment, or not subjected to any pre-refining treatment, the sulfur content can be not more than 300 mu g/g, and the nitrogen content can be not more than 5 mu g/g. Preferably, the sulfur content may be not greater than 200 μ g/g and the nitrogen content may be not greater than 2 μ g/g.

According to the present invention, the naphtha feedstock may be selected from at least one of straight run gasoline, hydrocracked gasoline, catalytically cracked gasoline, hydrocoker gasoline, reformed topped oil, reformed raffinate, condensate, pyrolysis gasoline and pyrolysis gasoline raffinate.

The invention is further illustrated by the following examples, but is not to be construed as being limited thereto.

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

The method for calculating the relative stability of the modified catalyst in the embodiment and the comparative example of the invention comprises the following steps: the catalyst one-way cycle running time of the examples or comparative examples/the catalyst one-way cycle running time of the reference (the relative stability of the modified catalyst of the comparative example is set to 1, and the remaining examples are based on the catalyst one-way cycle running time of the modified catalyst of the comparative example).

The composition of the liquid product is analyzed by adopting Shimadzu GC-2010AF chromatograph under the specific analysis conditions that: carrier gas N ₂ Capillary 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.

Example 1

Preparing a dehydrogenation catalyst.

Taking 100g (95 g on a dry basis) of gamma-Al ₂ O ₃ The carrier was used as a first carrier, the saturated water absorption was measured to be 82mL, 140mL of an impregnation solution was prepared using predetermined amounts of chloroplatinic acid and hydrochloric acid so that the impregnation solution contained 0.5 mass% of Pt and 1.9 mass% of Cl (both relative to the amount of the alumina dry substrate), and the volume ratio of the impregnation solution to the carrier was 1.05:1. the carrier was placed in flasks, the impregnation solution was introduced under a pressure of 0.085MPa, rotary impregnation was carried out at 30 ℃ for 3 hours at a linear speed of 0.10 m/sec, followed by drying under reduced pressure, and further drying in dry air at a gas/solid volume ratio of 700:1 for 4 hours. The catalyst obtained by the above method contained 0.5 mass% of Pt and 1.0 mass% of Cl based on a dry alumina carrier.

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

100g of the second carrier was taken out, and immersed in 100 ml of an aqueous solution containing 1.0 g of mixed rare earth chloride (produced by inner Mongolia Baoto rare earth industries Co., ltd., wherein 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 (analyzed by X-ray fluorescence) and the balance of a second support containing 64.6 mass% of HZSM-5 molecular sieve, 35.4 mass% of gamma-Al ₂ O ₃ And alpha value is 30.

Comparative example

The naphtha feedstock is upgraded by conventional combined dehydrogenation and upgrading processes.

In a laboratory fixed bed four-reactor adiabatic medium-sized test apparatus (4 reactors of the apparatus are arranged in series, the outlets of the first three reactors are provided with an on-line chromatograph, the composition of the product at the outlet of the reactor can be detected in real time, and the apparatus is provided with a gas circulation compressor), the first two reactors are filled with catalysts, the total loading amount of the catalysts is 120g, wherein the first reactor is filled with 15g of the dehydrogenation catalyst prepared in example 1 as a dehydrogenation reaction zone, and the second reactor is filled with 105g of the upgrading catalyst prepared in example 2 as an upgrading reaction zone.

Carrying out dehydration activation treatment on the dehydrogenation catalyst and the modification catalyst in the device before reaction, wherein an activation medium is nitrogen, and the reaction pressure is 0.4MPa, and the volume ratio of the nitrogen to the catalyst is 500: 1. the reactor inlet temperature is 400 ℃ and the activation time is 2h.

Introducing mixed naphtha shown in table 1 into a first reactor, contacting with a dehydrogenation catalyst to perform dehydrogenation reaction under dehydrogenation reaction conditions, 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 dehydrogenation product mixture of the first reactor into a second reactor, contacting with a modification catalyst to perform modification reaction under modification reaction conditions, and adjusting the inlet temperature of the second reactor by taking Research Octane Number (RON) 90 of a liquid product as a target. Cooling and separating the modified reaction product to obtain a gas-phase product and a liquid-phase product, and returning 80 volume percent of the gas-phase product to the first reactor. The liquid phase product and the residual gas phase product enter a product absorption-stabilization system to obtain a high-quality gasoline blending component (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 is 100g/h, and the total mass space velocity is 0.83h ^-1 The feed mass space velocity relative to the first reactor was 6.66h ^-1 The space velocity of the feed mass relative to the second reactor was 0.95h ^-1 (ii) a The initial reaction temperature of the first reactor is 380 ℃, the initial reaction temperature of the second reactor is 350 ℃, the temperature of the second reactor is gradually increased in the experimental operation process to ensure the control target of Research Octane Number (RON) 90 of a liquid product, finally, the temperature increasing effect is poor when the temperature of the second reactor is increased to 435 ℃, and the experiment is stopped when the RON of the liquid product is less than 90; the volume ratio of gas phase product returned to the first reactor during the run to naphtha feed was 280. The analysis data of the recycle gas composition in the reaction process are shown in Table 2, and the specific reaction result is shown in Table 3.

Example 3

A naphtha feedstock was upgraded by the method of the comparative example except that the temperature of the upgrading reaction in the upgrading reaction zone was 368 deg.C (T) ₁ ) When the reaction temperature is lower than the initial reaction temperature of 350 ℃ (T) ₀ ) Increase 18 ℃ (T) ₁ -T ₀ =18 ℃) where the activity of the reforming catalyst is reduced, the naphtha feedstock feed is stopped, and the carrier gas circulation is maintained. The temperature of the upgrading reactor (second reactor) was raised to 388 ℃ and held constant for 1 hour to activate the upgrading catalyst. During the activation treatment of the modifying catalyst, the material feeding is stopped in the dehydrogenation reaction zone, and the temperature of the first reactor is kept unchanged. After the activation treatment of the modifying catalyst, the temperature of the modifying reactor is reduced to 360 ℃, the naphtha raw material is reintroduced to carry out the reaction of the dehydrogenation and modification combined process, and then 360 ℃ is taken as the initial reaction temperature for the reaction after the first activation treatment of the modifying catalystThe method repeats the steps of reaction and activation until the temperature raising effect becomes worse when the modification temperature in the modification reaction zone is raised to 435 ℃, and stops the experiment when the RON of the liquid product is less than 90, and the reaction result is shown in Table 3.

Example 4

The naphtha feedstock was upgraded by the method of comparative example except that the upgrading reaction temperature in the upgrading reaction zone was 368 deg.C, which was 350 deg.C (T) higher than the initial reaction temperature ₀ ) Increasing the temperature to 18 ℃ is regarded as the activity of the upgrading catalyst is reduced, the feeding of naphtha raw material is stopped, and the circulation of carrier gas is maintained. The temperature of the upgrading reactor is increased to 418 ℃ and is kept constant for 1h, and the upgrading catalyst is activated. When the modification catalyst is activated, the dehydrogenation reaction zone stops feeding at the same time, and the temperature of the first reactor is kept unchanged. After the activation treatment of the upgrading catalyst is finished, the temperature of the upgrading reactor is reduced to 360 ℃, naphtha raw material is introduced again to carry out the reaction of the dehydrogenation and upgrading combined process, then 360 ℃ is taken as the initial reaction temperature of the reaction after the first activation treatment of the upgrading catalyst, the reaction and the activation steps are repeated according to the method, the temperature raising effect is poor when the reaction temperature of the upgrading reactor is raised to 435 ℃, the experiment is stopped when the RON of the liquid product is less than 90, and the reaction result is shown in table 3.

Example 5

The naphtha feedstock was upgraded by the method of the comparative example except that the upgrading reaction temperature in the upgrading reaction zone was 350 ℃ (T) as compared with the initial reaction temperature when the upgrading reaction temperature was 368 ℃ ₀ ) Increasing the temperature to 18 ℃ is regarded as the activity of the upgrading catalyst is reduced, the naphtha raw material feeding is stopped, the carrier gas circulation is maintained, the temperature of the upgrading reactor is maintained at 368 ℃ for 1h, and the upgrading catalyst is activated. When the modification catalyst is activated, the dehydrogenation reaction zone stops feeding at the same time, and the temperature of the first reactor is kept unchanged. Reducing the temperature of the upgrading reactor to 363 ℃ after the activation treatment of the upgrading catalyst, reintroducing the naphtha raw material to carry out the reaction of the dehydrogenation and upgrading combined process, then repeating the reaction and activation steps according to the method by taking 363 ℃ as the initial reaction temperature for the reaction after the first activation treatment of the upgrading catalyst until the reaction temperature of the upgrading reactor is increased to 435 DEG CThe temperature raising effect becomes poor, when the RON of the liquid product is less than 90, the experiment is stopped, and the reaction result is shown in Table 3.

Example 6

The naphtha feedstock was upgraded by the method of the comparative example except that the upgrading reaction temperature in the upgrading reaction zone was 350 ℃ (T) as compared with the initial reaction temperature when the upgrading reaction temperature was 368 ℃ ₀ ) Increasing the temperature to 18 ℃ is regarded as the activity of the reforming catalyst is reduced, the feeding of naphtha raw material is stopped, the carrier gas circulation is maintained, the temperature of the reforming reactor is increased to 388 ℃ for 2 hours, and the reforming catalyst is activated. When the modification catalyst is activated, the dehydrogenation reaction zone stops feeding at the same time, and the temperature of the first reactor is kept unchanged. After the activation treatment of the modifying catalyst is finished, the temperature of the modifying reactor is reduced to 360 ℃, naphtha raw material is reintroduced for the reaction of the dehydrogenation and modification combined process, then 360 ℃ is taken as the initial reaction temperature of the reaction after the first activation treatment of the modifying catalyst, the reaction and activation steps are repeated according to the method, the temperature raising effect is poor when the reaction temperature of the modifying reactor is raised to 435 ℃, and the experiment is stopped when the RON of the liquid product is less than 90. The reaction results are shown in Table 3.

Example 7

The naphtha feedstock was upgraded by the method of the comparative example except that the upgrading reaction temperature in the upgrading reaction zone was 350 ℃ (T) as compared with the initial reaction temperature when the upgrading reaction temperature was 368 ℃ ₀ ) Increasing the temperature to 18 ℃ is regarded as the activity of the upgrading catalyst is reduced, the naphtha raw material feeding is stopped, and the carrier gas circulation is maintained. The temperature of the upgrading reactor is increased to 388 ℃ and is kept constant for 0.5h, and the upgrading catalyst is activated. When the modification catalyst is activated, the dehydrogenation reaction zone stops feeding at the same time, and the temperature of the first reactor is kept unchanged. Reducing the temperature of the upgrading reactor to 360 ℃ after the activation treatment of the upgrading catalyst, reintroducing naphtha raw material for reaction of the dehydrogenation and upgrading combined process, then taking 360 ℃ as the initial reaction temperature of the reaction after the first activation treatment of the upgrading catalyst, repeating the reaction and activation steps according to the method until the temperature raising effect of the upgrading reactor is poor when the reaction temperature of the upgrading reactor is raised to 435 ℃, stopping the experiment when the RON of the liquid product is less than 90, and showing the reaction result in table3。

Example 8

The naphtha feedstock was upgraded by the method of comparative example, except that the temperature of the upgrading reaction in the upgrading reaction zone was 395 ℃ which was 350 ℃ (Tt) higher than the initial reaction temperature ₀ ) Raising the temperature to 45 ℃ is regarded as the activity of the upgrading catalyst is reduced, the feeding of naphtha raw material is stopped, and the circulation of carrier gas is maintained. The temperature of the upgrading reactor is increased to 415 ℃ and kept constant for 1h, and the upgrading catalyst is activated. When the modification catalyst is activated, the dehydrogenation reaction zone stops feeding at the same time, and the temperature of the first reactor is kept unchanged. After the activation treatment of the upgrading catalyst is finished, the temperature of the upgrading reactor is reduced to 386 ℃, naphtha raw material is reintroduced to carry out the reaction of the dehydrogenation and upgrading combined process, then 386 ℃ is taken as the initial reaction temperature of the reaction after the first activation treatment of the upgrading catalyst, the reaction and activation steps are repeated according to the method, the temperature raising effect is poor when the reaction temperature of the upgrading reactor is raised to 435 ℃, the experiment is stopped when the RON of the liquid product is less than 90, and the reaction result is shown in Table 3.

TABLE 1

TABLE 2

Components	Content, volume%
		H ₂	78.85
Methane	0.49
		Ethylene	0.10
Ethane (E)	0.29
		Propylene (PA)	0.27
Propane	11.21
		Carbon tetraolefins	0.25
C-tetra-alkanes	6.81
		Carbon pentaalkane	0.90
Hydrocarbons containing more than five carbon atoms	0.83

TABLE 3

Compared with the conventional dehydrogenation and modification combined process method, under the condition that the octane number of a liquid product is equivalent, when the naphtha is modified by adopting the method, the relative stability of the catalyst is greatly improved, and the one-way reaction time is prolonged.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are all within the protection scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as disclosed in the present disclosure, as long as it does not depart from the spirit of the present invention.

Claims

1. A naphtha upgrading method comprises the steps of introducing a naphtha raw material into a dehydrogenation reaction zone and an upgrading reaction zone which are arranged in series, enabling the naphtha raw material to be in contact with a dehydrogenation catalyst in the dehydrogenation reaction zone under the dehydrogenation reaction condition, sending an obtained dehydrogenation product into the upgrading reaction zone, being in contact with the upgrading catalyst under the upgrading reaction condition, cooling the obtained upgrading product, then carrying out gas-liquid separation, discharging a liquid-phase product out of a device, discharging a part of a gas-phase product, and returning the rest of the gas-phase product back to the dehydrogenation reaction zone to be used as a circulating gas;

when the octane number required by the liquid product of the upgrading reaction is maintained, and the temperature of the upgrading reaction is increased by 10-30 ℃ compared with the initial temperature for starting the reaction, the activity of the upgrading catalyst is reduced; and when the activity of the upgrading catalyst is reduced, stopping introducing the naphtha raw material, activating the upgrading catalyst under the condition of maintaining circulation of circulating gas, wherein the activation temperature is increased by 10-50 ℃ compared with the upgrading reaction temperature when the introduction of the naphtha raw material is stopped, and continuously introducing the naphtha raw material for reaction after the upgrading catalyst is activated.

2. The process according to claim 1, wherein the time for activating the reforming catalyst is 0.5 to 2 hours.

3. The process according to claim 1, wherein the gas phase products returned to the dehydrogenation reaction zone comprise 30-90 vol% of the total gas phase products.

4. The method of claim 1, wherein the dehydrogenation reaction conditions comprise: the temperature is 360-480 ℃, the pressure is 0.1-1MPa, and the mass space velocity of the naphtha raw material is 2-20h ^-1 The volume ratio of the gas-phase product returned to the dehydrogenation reaction zone to the naphtha raw material is (100-1000): 1.

5. the process of claim 1, wherein the upgrading reaction conditions comprise: the temperature is 280-460 ℃, the pressure is 0.1-1MPa, and the mass space velocity of the naphtha raw material is 0.2-5h ^-1 。

6. The method of claim 1, wherein the method further comprises: in the dehydrogenation reaction zone, from 20 to 50 mass% of the naphthenes are converted to aromatics, based on the total mass of naphthenes in the naphtha feedstock.

7. The method of claim 1, wherein the method further comprises: after the upgrading catalyst is activated, the temperature of the upgrading catalyst is reduced to be 3-10 ℃ lower than the upgrading reaction temperature when the naphtha raw material is stopped being introduced, and then the naphtha raw material is continuously introduced for reaction.

8. The process according to claim 1, wherein the loading of the dehydrogenation catalyst in the dehydrogenation reaction zone is from 5 to 50 mass% based on the total loading of the dehydrogenation catalyst and the upgrading catalyst.

9. The process of claim 1, wherein the dehydrogenation catalyst comprises a first support and a group VIII metal in an amount of from 0.05 to 1 mass% and from 0.1 to 5 mass% chlorine, on a dry first support basis.

10. According to the claimThe process of claim 1, wherein the upgrading catalyst comprises 0.1 to 5 mass% of the metal oxide and 95 to 99.9 mass% of the second support; the metal oxide is one or more selected from zinc oxide, antimony oxide, mixed rare earth oxide, bismuth oxide, molybdenum oxide and gallium oxide, and the second carrier comprises 50-80 mass% of HZSM-5 molecular sieve and 20-50 mass% of gamma-Al ₂ O ₃ 。

11. A process according to claim 1, wherein the naphtha feed has a head point in the range of 40-90 ℃, an end point in the range of 120-210 ℃, a naphthenes content in the range of 15-50 mass%, and the naphtha feed contains C ₅ -C ₁₂ The hydrocarbon (2) has a sulfur content of not more than 200. Mu.g/g and a nitrogen content of not more than 5. Mu.g/g.

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