阅读说明：本技术 一种贵金属负载型催化剂在合成对二甲苯中的应用 (Application of noble metal supported catalyst in synthesizing paraxylene ) 是由 李昌志 孟庆伟 肖钰雪 张涛 于 2019-11-21 设计创作，主要内容包括：本发明提供一种贵金属负载型催化剂在合成对二甲苯中的应用。具体地说就是4-甲基-3-环己烯甲醛在铁调变的贵金属催化剂作用下,于250℃-450℃发生脱氢芳化和原位加氢脱氧反应,生成对二甲苯的方法。本发明可分别在固定床反应器、流化床反应器或移动床反应器中进行,反应原料直接注射进入反应管,或在载气的吹扫下经过催化剂床层而获得对二甲苯,摩尔收率达到80％以上。该过程反应条件温和,工序简单,目标产物选择性高,提供了贵金属催化生物质资源制备对二甲苯新策略。(The invention provides an application of a noble metal supported catalyst in synthesizing paraxylene. In particular to a method for generating p-xylene by carrying out dehydroaromatization and in-situ hydrodeoxygenation reactions on 4-methyl-3-cyclohexene formaldehyde at the temperature of 250-450 ℃ under the action of a noble metal catalyst modulated by iron. The method can be carried out in a fixed bed reactor, a fluidized bed reactor or a moving bed reactor respectively, reaction raw materials are directly injected into a reaction tube or pass through a catalyst bed layer under the sweeping of carrier gas to obtain the p-xylene, and the molar yield reaches over 80 percent. The process has mild reaction conditions, simple working procedures and high selectivity of target products, and provides a new strategy for preparing the paraxylene by catalyzing biomass resources with noble metals.)

1. The application of a noble metal supported catalyst in the reaction of synthesizing p-xylene selectively from 4-methyl-3-cyclohexene formaldehyde is characterized in that the noble metal supported catalyst comprises an active component and a carrier; the active component comprises a noble metal and iron; the content of the noble metal of the catalyst is 0.5-10 wt%; the loading of iron is 0.5 wt% -30 wt%.

2. The use according to claim 1, wherein the noble metal is at least one of palladium, platinum, rhodium; the carrier is at least one of activated carbon, alumina, silica, zirconia, titanium dioxide, a silicon-aluminum molecular sieve and a phosphorus-aluminum molecular sieve; the specific surface area of the carrier is more than 150m²G, pore volume > 0.35m³(g), bulk density 670-³。

3. The use of claim 1, wherein the catalyst is prepared by an impregnation method, the drying temperature is 60-120 ℃, and the drying time is 2-12 h; the roasting temperature is 400-600 ℃, and the roasting time is 4-6 h.

4. The use of claim 1, wherein the reaction process is that 4-methyl-3-cyclohexene formaldehyde enters a gas-solid phase reactor filled with the noble metal supported catalyst under the carrier gas purging and carrying, and catalytic dehydrogenation of six-membered ring and hydrodeoxygenation reaction of aldehyde group simultaneously occur to generate p-xylene at the temperature of 250-400 ℃ and under the condition of 0.1Mpa-1 Mpa.

5. Use according to claim 4, characterized in that: after the 4-methyl-3-cyclohexene formaldehyde is heated to 50-200 ℃, 4-methyl-3-cyclohexene formaldehyde steam is transferred into a gas-solid phase reactor by carrier gas; or the 4-methyl-3-cyclohexene formaldehyde is swept by a carrier gas in a raw material bottle and enters a gas-solid phase reactor for reaction.

6. Use according to claim 4, characterized in that: the gas-solid phase reactor is a fixed bed reactor, a fluidized bed reactor or a moving bed reactor, and preferably is a fixed bed reactor.

7. Use according to claim 4, characterized in that: the reaction temperature is 250-350 ℃; the mass space velocity of the reaction is 0.1-10h^-1。

8. Use according to claim 4, characterized in that: the carrier gas is at least one of hydrogen, nitrogen and helium.

9. Use according to claim 4, characterized in that: and the reaction product p-xylene is led out from the gas-solid phase reactor and then is cooled and collected by liquid nitrogen or ice water, and the cooling temperature is controlled below 10 ℃.

10. The use of claim 7, wherein the catalytic reaction mass space velocity is 0.1-0.5h^-1。

Technical Field

The invention belongs to the field of preparing aromatic hydrocarbon by catalyzing biomass with noble metal, and particularly relates to a noble metal supported catalyst, a preparation method thereof and application thereof in synthesizing p-xylene.

Background

Aromatic hydrocarbon is an important basic chemical, and various product chains can be derived by utilizing aromatic hydrocarbon resources, so that the aromatic hydrocarbon can be widely applied to the fields of synthetic resin, synthetic fiber monomers, coatings, fuels, medicines, fine chemicals and the like. Polyethylene terephthalate (PET) is a polyester that is currently in widespread use, and para-xylene is an essential monomer for the production of PET. With the rapid development of the global polyester industry, the demand for paraxylene has also increased year by year. The traditional method for producing p-xylene is to obtain carbon octa-arene from naphtha catalytic reforming, and then separate the p-xylene from an isomer mixture with a similar boiling point by a multi-stage separation or molecular sieve simulated moving bed adsorption separation (called adsorption separation for short) technology. Due to the current situation of more coal and less petroleum in China, a route of using coal as a raw material, preparing methanol from the coal, preparing aromatic hydrocarbon from the methanol, and separating and extracting paraxylene from the aromatic hydrocarbon is also developed (petrochemical technology and economy, 2013, 29-3-14).

Due to the limited reserves of coal and petroleum resources and the utilization of fossil resources, a series of environmental problems are brought, and the production of chemical products and fuels by using renewable biomass resources as raw materials becomes one of the feasible ways of relieving energy and environmental crises. In addition, the reaction conditions in the joint production process of the aromatic hydrocarbon are harsh, the process route is long, the energy consumption is high, and the development of a short and high-efficiency conversion technology has important significance for industrial production.

In recent years, various energy petrochemical companies, research institutions and colleges all have great interest in biomass aromatic hydrocarbon preparation processes. Various biomass resource methods for producing paraxylene have been developed. For example, in 2009, Gevo corporation of america developed the synthesis of aromatic hydrocarbons from biomass-based isobutanol as a raw material through dehydration, dimerization, and cyclodehydrogenation. Gevo currently works with Dongli corporation to build an industrial plant (Petro Chemical News, 2011-11-28). UOP in its patent (CN102482177, US20100331568) synthesizes 2, 5-Dimethylfuran (DMF) from biomass feedstock (glucose or polysaccharides) and reacts with ethylene by catalytic cycloaddition (Diels-Alder) to produce oxabicycloheptene derivatives, which are subsequently subjected to ring opening and dehydration to obtain p-xylene. The Dongli company of Japan uses a supported noble metal catalyst to prepare a mixture of p-tolualdehyde and p-xylene through cyclization, aromatization and dehydration from isoprene and acrolein (CN 104010996A). The method can also prepare the p-xylene by using biomass ethanol as a raw material through steps of dehydration reaction, dimerization reaction, cyclodehydrogenation and the like under the catalysis of an acidic molecular sieve (Chemical Engineering Journal,2009,154, 396-400.). This unit also reports 4-methyl-3-cyclohexene carbaldehyde produced by the Diels-Alder reaction of isoprene and acrolein, which was then aromatized to p-xylene over a tungsten-based catalyst (angelwald chemical International Edition,2018,7, 1808-.

Disclosure of Invention

The invention aims to provide a method for preparing p-xylene by using a noble metal modulation method, which can inhibit a decarbonylation side reaction of 4-methyl-3-cyclohexene formaldehyde and catalyze the decarbonylation side reaction to simultaneously carry out an arylation reaction and an in-situ hydrodeoxygenation reaction in a fixed bed reactor.

In order to achieve the purpose, the invention adopts the technical scheme that:

the invention also provides an application of the noble metal supported catalyst, and the noble metal supported catalyst is applied to the reaction of preparing p-xylene from 4-methyl-3-cyclohexene formaldehyde. A process for selectively preparing p-xylene from p-Methyl cyclohexene formaldehyde (4-Methyl-3-cyclohexene formaldehyde, English name: 4-Methyl-3-cyclohexene-1-carbaldehyde). In particular to a method for generating p-xylene by carrying out dehydroaromatization and in-situ hydrodeoxygenation on 4-methyl-3-cyclohexene formaldehyde at the temperature of 250-450 ℃ under the action of a noble metal catalyst. The method is carried out in a fixed bed reactor, and reaction raw materials are injected into a catalyst bed layer under the sweeping of carrier gas or by an injection pump so as to obtain the paraxylene. The process uses a noble metal catalyst, and the preparation method of the present invention can be described by the following equation (formula 1):

the supported catalyst comprises an active component and a carrier; the supported iron modulated noble metal catalyst consists of two parts, namely an active component and a carrier; the active component comprises a noble metal and iron; iron is used as an auxiliary agent to modulate noble metal; the content of the noble metal active component of the catalyst on the catalyst is 0.5-10 wt%; the content of the iron auxiliary agent on the catalyst is 0.5 wt% -30 wt%.

Based on the technical scheme, preferably, the noble metal is one or more of palladium, platinum and rhodium; the carrier is one or more of activated carbon, alumina, silica, zirconia, titanium dioxide, a silicon-aluminum molecular sieve and a phosphorus-aluminum molecular sieve; the specific surface area of the carrier is more than 150m²G, pore volume > 0.35m³(g), bulk density 670-³。

Based on the technical scheme, preferably, the preparation method of the noble metal supported catalyst is an impregnation method, wherein a certain content of ferric nitrate (the metal content is 0.5-30%) and a certain content of noble metal nitrate (the metal content is 0.5-10%) are impregnated on a specific carrier together, and then the carrier is dried at 60-120 ℃ for 2-12 hours and roasted at 400-600 ℃ for 4-6 hours;

based on the technical scheme, preferably, under the action of a pump, 4-methyl-3-cyclohexene formaldehyde is brought into a fixed bed reactor filled with a catalyst from a raw material bottle by a carrier gas, catalytic dehydrogenation of a six-membered ring and hydrodeoxygenation of aldehyde groups simultaneously occur to generate p-xylene, and a product is cooled by ice water and then collected, and the yield of the product is calculated by using an internal standard method.

Based on the technical scheme, preferably, the 4-methyl-3-cyclohexene formaldehyde reaction raw material is injected by an injection pump, heated to 50-200 ℃, and then transferred into a gas-solid phase reactor by carrier gas; or the 4-methyl-3-cyclohexene formaldehyde reaction raw material can be swept by a carrier gas in a raw material bottle to enter a gas-solid phase reactor for reaction.

Based on the technical scheme, the gas-solid phase reactor is preferably a fixed bed reactor, a fluidized bed reactor or a moving bed reactor, and is preferably a fixed bed reactor.

Based on the above technical solution, preferably, the carrier gas is selected from one of hydrogen, nitrogen, helium or a mixture thereof.

In the catalytic dehydrogenation of the six-membered ring and the hydrodeoxygenation of the aldehyde group, a fixed bed is filled with a certain mass of catalyst, wherein the active center of the catalyst is mainly noble metal. In the catalytic dehydrogenation and aldehyde group hydrodeoxygenation experiments of the six-membered ring, the mass ratio of the mass of the catalyst to the mass of the substrate in unit time is 0.01-20, namely the mass space velocity of the catalytic reaction is 0.01-20h^-1. Wherein the more preferable condition is that the ratio of the mass of the catalyst to the mass of the substrate per unit time is from 0.1 to 10. The ratio of the mass of the catalyst to the mass of the unit substrate is more preferably 0.5 to 5.

Based on the technical scheme, in the preferable catalytic dehydrogenation of the six-membered ring and the hydrodeoxygenation reaction of the aldehyde group, the reaction temperature is 250-350 ℃, the reaction pressure is 0.1MPa, and the flow rate of carrier gas is 8-400 mL/min; the optimized reaction conditions are that the reaction temperature is 250-350 ℃, the reaction pressure is 0.1MPa, and the flow rate of the carrier gas is 8-200 mL/min;

advantageous effects

(1) The preparation method of the catalyst is simpler, and the iron-modulated noble metal supported catalyst is used for catalyzing the 4-methyl-3-cyclohexene formaldehyde to prepare the p-xylene tweed, so that on one hand, the catalytic reaction process of the iron-modulated noble metal supported catalyst is milder, the selectivity of a target product is high, and on the other hand, the substrate 4-methyl-3-cyclohexene formaldehyde can be efficiently generated from isoprene and acrolein through a Diels-Alder reaction (CN 104010996A), and the isoprene and the acrolein can be derived from fossil resources and biomass resources. For example: isoprene can be produced by fermentation of natural lignocellulose resources (CN 201310670581.5); acrolein can be produced by dehydration of glycerol, a by-product of biodiesel (Petro Chemical News, 2011-11-28).

(2) According to the invention, on the basis of the existing noble metal catalytic reaction, the strategy is modulated, the auxiliary agent iron is added while the noble metal is loaded on the carrier, the decarbonylation side reaction is greatly inhibited by the modulation of the noble metal through the iron, the p-xylene is prepared at a higher yield at a reaction temperature lower than that of the prior art, and the mode of preparing aromatic chemicals from biomass resources under a milder condition is realized.

(3) The method has the advantages of mild reaction conditions, simple process and high selectivity of the target product. The method generates a small amount of toluene as a byproduct, and can generate benzene and C8 aromatic hydrocarbon through disproportionation or transalkylation of aromatic hydrocarbon of C9 or above (toluene disproportionation and transalkylation for short), thereby being an effective process route for increasing the yield of p-xylene.

Detailed Description

Examples 1 to 5

6 ml of palladium nitrate solution with the concentration of 10 mg per ml and 0.2 g of ferric nitrate nonahydrate are prepared into 6 ml of aqueous solution, 6g of alumina carrier is added, the solution is soaked for 5 hours, dried for 12 hours at the temperature of 80 ℃, and then roasted for 4 hours at the temperature of 450 ℃. A noble metal catalyst was obtained with a mass content of palladium and iron of 1 wt.%, and this catalyst was reported as 1Pd1Fe/Al₂O₃。

The amount of metallic iron salt is changed, and the catalyst 1Pd1Fe/Al with different loading amounts is prepared₂O₃，1Pd3Fe/Al₂O₃，1Pd5Fe/Al₂O₃，1Pd7Fe/Al₂O₃，1Pd10Fe/Al₂O₃。

Comparative example 1

Catalyst preparation As in example 1, without addition of metallic iron salt, 1Pd/Al is obtained₂O₃。

Comparative example 2

Catalyst preparation As in example 1, without addition of the noble metal palladium salt, 10Fe/Al is obtained₂O₃。

Example 6

Catalyst preparation as in example 1, the amount of metal salt was varied, the drying procedure was varied to 120 ℃ for 2 hours and the calcination procedure was varied to 600 ℃ for 6 hours. Preparation of catalyst 10Pd30Fe/Al₂O₃。

Examples 7 to 9

The catalyst was prepared as in example 5 except that the alumina carrier was replaced with Activated Carbon (AC), zirconia, and silica, respectively, and the Activated Carbon (AC) was calcined in a nitrogen atmosphere to prepare 1Pd10Fe/SiO₂，1Pd10Fe/AC，1Pd10Fe/ZrO₂。

Comparative examples 3 to 5

Comparative example 3: catalyst preparation As comparative example 1, the alumina supports were exchanged for silica respectively to give 1Pd/SiO₂；

Comparative example 4: catalyst preparation as in comparative example 1, the alumina supports were exchanged for Activated Carbon (AC) respectively to give 1 Pd/AC;

comparative example 5: catalyst preparation As in comparative example 1, the alumina supports were exchanged for zirconia respectively to give 1Pd/ZrO₂。

Example 10

Catalyst preparation platinum-based catalyst 1Pt10Fe/Al was prepared as in example 1, except that the palladium nitrate solution was changed to the chloroplatinic acid solution₂O₃。

Comparative example 6

Catalyst preparation As in example 1, except that the palladium nitrate solution was changed to the chloroplatinic acid solution to prepare 1Pt/Al₂O₃。

Example 11

Catalyst preparation the catalyst preparation was as in example 1 except that the palladium nitrate solution was changed to rhodium nitrate solution to prepare rhodium-based catalyst 1Rh10Fe/Al₂O₃。

Comparative example 7

Catalyst preparation As in example 1, except that the palladium nitrate solution was changed to the rhodium nitrate solution to prepare the catalyst 1Rh/Al₂O₃。

Comparative example 8

The preparation procedure was the same as in comparative example 1, replacing ferric nitrate with nickel nitrate to give 1% wtNi/Al₂O₃。

Comparative examples 9 to 13

NiFe/Al₂O₃Preparation of the catalyst: 1% Ni 1% Fe/Al₂O₃For example, 0.36g of iron nitrate nonahydrate was dissolved in 6.5g of pure water to obtain an iron nitrate solution, and after stirring the solution uniformly, the above was taken out5g of 1% wtNi/Al thus prepared₂O₃Soaking in the ferric nitrate solution, ultrasonic treating for 30min in an ultrasonic machine (100Hz), standing for 12h, baking at 80 deg.C for 12h, and baking at 100 deg.C for 4 h. Calcining at 500 deg.C in air for 4h, reducing at 550 deg.C in hydrogen atmosphere for 1h, and controlling hydrogen flow rate at 120 mL/min. After the reduction, the temperature is reduced to room temperature, and 5 percent volO is adopted₂/N₂Passivating for 4 hours in the mixed gas to obtain 1Ni1Fe/Al₂O₃A bimetallic catalyst. 1Ni3Fe/Al is prepared respectively by changing the amount of the metal precursor₂O₃，1Ni5Fe/Al₂O₃，1Ni7Fe/Al₂O₃，1Ni10Fe/Al₂O₃A catalyst.

Example 12

Dissolving 4-methyl-3-cyclohexene formaldehyde and 1, 4-dioxane in a certain proportion to obtain a 4-methyl-3-cyclohexene formaldehyde solution with a certain mass concentration, adding a certain amount of internal standard substance, namely n-tridecane, injecting the mixed solution into a bed layer filled with a certain amount of catalyst by using a constant-flow pump, carrying out dehydroaromatization and aldehyde group hydrodeoxygenation on the 4-methyl-3-cyclohexene formaldehyde at a certain temperature, a certain reaction pressure and a certain hydrogen/nitrogen flow rate, cooling and collecting the reacted product by using ice water, and carrying out qualitative analysis by using GC-MS and quantitative analysis by using a GC internal standard method. The reaction conditions and the kind of catalyst were varied, and the specific reaction results are shown in table 1.

TABLE 1 reaction results of dehydroaromatization of 4-methyl-3-cyclohexenecarbaldehyde and preparation of p-xylene by aldehyde group hydrodeoxygenation

The above results show that the reaction temperature is 250-400 ℃ at normal pressure, and 1Pd10Fe/Al is₂O₃，1Pd10Fe/C，1Pt10Fe/Al₂O₃Catalyzing 4-methyl-3-cyclohexene formaldehyde to perform dehydroaromatization and aldehyde group hydrogenation removalThe yield of the p-xylene generated by the oxygen reaction is 50 to 92 percent.