Aromatic chemical synthesis process

Abstract

The invention provides an aromatic hydrocarbon chemical synthesis process, which is characterized by comprising the following steps: mixing a certain amount of CO into a mixed gas of H2 and CO2 in a volume ratio of 1: (2-5) to serve as a reaction raw material gas, and reacting at the temperature of 60-80 DEG C under the action of a specific metal oxide and molecular sieve composite catalyst, controlling the feeding space velocity of the reaction raw materials to be 500-2400 mL / h.gcat, the reaction temperature to be 300-550 DEG C and the reaction pressure to be 2-6 Mpa, and carrying out catalytic conversion to obtain an aromatic chemical; according to the method, a certain amount of CO is doped into reaction raw material gas, and a specific metal oxide and molecular sieve composite catalyst is selected to catalyze conversion of H2 and CO2 into aromatic chemicals; compared with the reaction atmosphere of pure H2 and CO2, the doping of CO greatly enhances the concentration of oxygen vacancies on the surface of the metal oxide, so that the ability of the metal oxide to catalyze CO2 to hydrogen-containing C1 species is greatly enhanced, the catalytic conversion rate of CO2 is improved, and the selectivity of aromatic chemicals is finally improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic chemical preparation, and in particular to a synthesis process of aromatic chemicals. Background Art

[0002] Aromatics are important bulk organic chemical raw materials, mainly used in the production of various polymers such as nylon, polyester, resin, polyurethane, film, etc. At present, more than 70% of the world's light aromatics (BTX) are produced by naphtha reforming. Therefore, it is crucial to develop a non-petroleum-based route to prepare aromatics.

[0003] Carbon dioxide (CO2) is the most important greenhouse gas and the main factor causing global warming. With the gradual escalation of carbon emission restrictions worldwide, the clean and efficient utilization of the large amount of carbon dioxide produced by the coal chemical process is both the focus of academic research and the bottleneck faced by the future industry. Since carbon dioxide, as the highest oxidation state of carbon, has extremely high chemical inertness, its clean and efficient conversion has become a key research focus. Therefore, the direct conversion of CO2 into aromatics is of great strategic significance and is also a very challenging topic.

[0004] In the CO2 hydrogenation to aromatics reaction, CO2 first generates hydrogen-containing C1 species on metal oxides, and then zeolite components such as H-ZSM-5 convert them into aromatics. However, the conversion rate of CO2 in this type of reaction is not ideal, about 10-30%. How to improve the conversion rate of CO2 in the CO2 hydrogenation to aromatics reaction is the key to improving the selectivity of aromatics. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a process for synthesizing aromatic chemicals to solve the problem of low CO2 conversion rate in the CO2 hydrogenation reaction to produce aromatics in the prior art.

[0006] The specific content of the invention is as follows: The present invention provides a process for synthesizing aromatic chemicals, the process comprising: A certain amount of CO is added to a mixed gas of H2 and CO2 in a volume ratio of 1:2-5 as a reaction raw material gas, and under the action of a first catalyst, a second catalyst or a third catalyst, the reaction raw material feed space velocity is controlled to be 500-2400 mL / h·gcat, the reaction temperature is 300-550°C, and the reaction pressure is 2-6 MPa, and catalytic conversion is performed to obtain aromatic chemicals; Wherein, the first catalyst is formed by combining a lanthanum perovskite oxide with a chemical formula of ABO3 and a molecular sieve; the A is selected from lanthanum or cerium, the B is selected from a transition metal, or the B is composed of a transition metal and a noble metal, the mass fraction of the noble metal is 0.00wt% to 4wt%, the molar ratio of A to B is 0.8:1 to 1:0.8, the transition metal is chromium, manganese, iron, cobalt or nickel, and the noble metal is ruthenium, rhodium, palladium, iridium or platinum; The second catalyst is composed of a metal oxide with defect vacancies on the surface and a single metal atom, wherein the single metal atom is uniformly loaded on the surface of the metal oxide in the form of chemical bonds to form a regular surface atomic arrangement; the metal oxide is MnO x 、ZrO、MoO、ZnZrO x , ZnMoO or ZnCr2O x ; The single metal atom is Zn, Cu, Cr, Mn, Pd, Zr, Al, Mo, Ge, In, Ni, Au, Fe or Y; the mass of the single metal atom accounts for 0.01 to 10% of the mass of the metal oxide; The third catalyst is composed of an alkaline metal oxide and a molecular sieve in a weight ratio of 0.1:10, and the alkaline metal oxide includes MnO, CrO, ZrO, GeO, NiO, ZnCrO x 、ZnPdO x or ZnMoO x .

[0007] Optionally, in the reaction raw material gas, the volume proportion of CO is 3-12%.

[0008] Optionally, the volume proportion of CO in the reaction raw gas is 4%.

[0009] Optionally, the reaction raw material feed space velocity is 600 mL / h·gcat, the reaction temperature is 300° C., and the reaction pressure is 3 Mpa.

[0010] Optionally, the molecular sieve is selected from H-ZSM5, ZSM-5, ZSM-11 or ZSM-48.

[0011] Optionally, the ABO3 is LaFeO3, LaCoO3, LaNiO3, LaMnO3 or LaFe 0.97 Pd 0.03 O3.

[0012] Optionally, the ABO3 is LaFeO3.

[0013] Optionally, the molecular sieve is H-ZSM5, and the ABO3 is LaFeO3; The selectivity of the aromatic chemicals is not less than 70%, and the C1 conversion rate is greater than 30%.

[0014] Optionally, the aromatic chemicals are primarily para-xylene and benzene.

[0015] Optionally, paraxylene accounts for more than 80% of the aromatic chemicals.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention provides a process for synthesizing aromatic chemicals, which comprises: adding a certain amount of CO as a reaction raw material gas to a mixed gas of H2 and CO2 with a volume ratio of 1:2-5, and controlling the reaction raw material feed space velocity to be 500-2400 mL / h·gcat, the reaction temperature to be 300-550°C, and the reaction pressure to be 2-6 under the action of a first catalyst, a second catalyst or a third catalyst. Mpa, catalytic conversion is carried out to obtain aromatic chemicals; wherein the first catalyst is formed by combining a lanthanide perovskite oxide with a chemical formula of ABO3 and a hydrogen-type molecular sieve with two-dimensional or three-dimensional pores; the A is selected from lanthanum or cerium, the B is selected from transition metals, or the B is composed of transition metals and noble metals, the mass fraction of the noble metal is 0.00wt% to 4wt%, the molar ratio of A to B is 0.8:1 to 1:0.8, the transition metal is chromium, manganese, iron, cobalt or nickel, and the noble metal is ruthenium, rhodium, palladium, iridium or platinum; the second catalyst is composed of a metal oxide with defect vacancies on the surface and a single metal atom, and the single metal atom is uniformly loaded on the surface of the metal oxide in the form of chemical bonds to form a regular surface atomic arrangement; the metal oxide is MnO x 、ZrO、MoO、ZnZrO x , ZnMoO or ZnCr2O x ; The single metal atom is Zn, Cu, Cr, Mn, Pd, Zr, Al, Mo, Ge, In, Ni, Au, Fe or Y; The mass of the single metal atom accounts for 0.01-10% of the mass of the metal oxide; The third catalyst is composed of an alkaline metal oxide and a molecular sieve in a weight ratio of 0.1:10, and the alkaline metal oxide includes MnO, CrO, ZrO, GeO, NiO, ZnCrO x 、ZnPdO x or ZnMoO x .

[0017] The present invention adds a certain amount of CO to the reaction raw material gas, and selects the first catalyst, the second catalyst or the third catalyst to catalyze the conversion of H2 and CO2 to aromatic chemicals; compared with the reaction atmosphere of pure H2 and CO2, the addition of CO is conducive to the catalyst to maintain a stable crystal form without change under the CO system, and further increases the surface oxygen vacancy active sites. , so that the ability of the catalyst to catalyze CO2→hydrogen-containing C1 species is greatly enhanced, the catalytic conversion rate of CO2 is improved, and finally the selectivity of aromatic chemicals is improved.

[0018] The process for synthesizing aromatic chemicals provided by the present invention, especially for the catalyst formed by the composite of LaFeO3 perovskite matrix and nano H-ZSM5 (used for catalyzing the conversion of H2 and CO2 into aromatic chemicals, with the selectivity of aromatics in hydrocarbon groups <70%), when a certain amount of CO is added to the H2 and CO2 reaction raw gas for catalytic conversion, the selectivity of aromatics in hydrocarbon groups can reach up to 82%, and is not less than 70%, and the improvement effect is very obvious whether it is the CO2 conversion rate or the improvement of the selectivity of aromatic chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The XRD patterns of LaFeO3 catalysts at different CO doping concentrations are shown; Figure 2 The concentration changes of oxygen vacancies on the surface of LaFeO3 catalyst under different CO doping concentrations are shown; Figure 3 The effect of space velocity on the aromatic chemical synthesis process provided by the embodiment of the present invention is shown; Figure 4 The effect of pressure on the aromatic hydrocarbon chemical synthesis process provided by the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments of the present invention, any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts falls within the scope of protection of the present invention. In addition, all other embodiments obtained by ordinary technicians in this field without carrying out creative work belong to the scope of protection of the present invention.

[0022] In the embodiment, no specific experimental steps or conditions are indicated, and the operation or conditions of the conventional experimental steps described in the prior art in this field can be carried out. The reagents used and other instruments that do not indicate the manufacturer are conventional reagent products that can be obtained commercially. In addition, the accompanying drawings are only schematic diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0023] Technologies, methods, and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the description of the present invention.

[0024] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0025] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] The present invention provides a process for synthesizing aromatic chemicals, and the specific synthesis process is as follows: A certain amount of CO is added to a mixture of H2 and CO2 in a volume ratio of 1:2-5 as a reaction raw material gas, and under the action of the first catalyst, the second catalyst or the third catalyst, the reaction raw material feed space velocity is controlled to be 500-2400 mL / h·gcat, the reaction temperature is 300-550°C, and the reaction pressure is 2-6 Mpa, catalytic conversion is carried out to obtain aromatic chemicals; wherein the first catalyst is formed by combining a lanthanide perovskite oxide with a chemical formula of ABO3 and a hydrogen-type molecular sieve with two-dimensional or three-dimensional pores; the A is selected from lanthanum or cerium, the B is selected from transition metals, or the B is composed of transition metals and noble metals, the mass fraction of the noble metal is 0.00wt% to 4wt%, the molar ratio of A to B is 0.8:1 to 1:0.8, the transition metal is chromium, manganese, iron, cobalt or nickel, and the noble metal is ruthenium, rhodium, palladium, iridium or platinum; the second catalyst is composed of a metal oxide with defect vacancies on the surface and a single metal atom, and the single metal atom is uniformly loaded on the surface of the metal oxide in the form of chemical bonds to form a regular surface atomic arrangement; the metal oxide is MnO x 、ZrO、MoO、ZnZrO x , ZnMoO or ZnCr2O x ; The single metal atom is Zn, Cu, Cr, Mn, Pd, Zr, Al, Mo, Ge, In, Ni, Au, Fe or Y; The mass of the single metal atom accounts for 0.01 to 10% of the mass of the metal oxide; The third catalyst is composed of an alkaline metal oxide and a molecular sieve in a weight ratio of 0.1:10, and the alkaline metal oxide includes MnO, CrO, ZrO, GeO, NiO, ZnCrO x 、ZnPdO x or ZnMoO x .

[0027] In specific implementation, the present invention adds a certain amount of CO to the reaction raw gas, and selects the first catalyst, the second catalyst or the third catalyst to catalyze the conversion of H2 and CO2 into aromatic chemicals; compared with the reaction atmosphere of pure H2 and CO2, the addition of CO greatly increases the concentration of oxygen vacancies on the catalyst surface, so that the ability of the catalyst to catalyze CO2→hydrogen-containing C1 species is greatly enhanced, the catalytic conversion rate of CO2 is improved, and ultimately the selectivity of aromatic chemicals is improved.

[0028] In some embodiments, in the first catalyst, the lanthanide perovskite oxide ABO3 is selected from LaFeO3, LaCoO3, LaNiO3, LaMnO3 or LaFe 0.97 Pd 0.03O3, the molecular sieve is H-ZSM5; as a preferred result, the lanthanide perovskite oxide ABO3 is LaFeO3, and the molecular sieve is H-ZSM5. The embodiment of the present invention is particularly directed to a catalyst formed by a composite of a LaFeO3 perovskite matrix and nano-H-ZSM5. When a certain amount of CO is added to the H2 and CO2 reaction raw gas for catalytic conversion, the selectivity of aromatics in the hydrocarbon group is not less than 70%, the C1 conversion rate is greater than 30%, and the C1 conversion rate is greater than 30%; the aromatic chemicals are mainly p-xylene and benzene; whether it is the CO2 conversion rate or the improvement of the selectivity of aromatic chemicals, the improvement effect is very obvious.

[0029] In some embodiments, in the second catalyst, the metal spontaneously falling catalyst may be a catalyst composed of Fe atoms uniformly supported on ZnCr2O x The double metal oxide support surface is formed. That is, the metal oxide is specifically ZnCr2O x , the single metal atom is specifically Fe, Fe accounts for ZnCr2O x The metal spontaneous deposition catalyst can also be a single metal oxide MnO uniformly loaded with Cr atoms. X The support surface is formed, that is, the metal oxide is specifically MnO X , the single metal atom is specifically Cr, Cr accounts for MnO X 5% of mass.

[0030] In specific implementation, the selection of the amount of CO added is very critical to improving the catalytic conversion rate of CO2. Through a large number of experimental studies, the embodiments of the present invention found that maintaining the volume proportion of CO in the reaction raw gas at 3-12% has a significant effect on improving the catalytic conversion rate of CO2. In particular, when the volume proportion of CO in the reaction raw gas is maintained at 4%, the catalytic conversion rate of CO2 is improved the most.

[0031] In the embodiment of the present invention, the preparation process of the first catalyst is as follows: a perovskite matrix and a molecular sieve are mixed in a mass ratio of 1:1, placed in a reducing atmosphere, and reduced at 0.5-2 MPa and 200-450° C. for 1-3 h to form a lanthanide perovskite oxide and molecular sieve composite catalyst; In the embodiment of the present invention, the preparation process of the second catalyst is as follows: a metal oxide precursor solution and a precipitant with a pH of not less than 8.5 are slowly mixed under continuous stirring to obtain a first mixed solution, and the temperature is maintained at 70°C to 100°C and the pH is maintained at 5.5-8.5 during the mixing process. After the mixing is completed, the mixture is transferred to a nitrogen atmosphere and continuously stirred for crystallization for 6-48 hours to obtain a second mixed solution; the second mixed solution is mixed with a carbon source template agent in a volume ratio of 1:0.01-0.1, stirred for 4-26 hours, and then filtered and calcined. A metal oxide with defect vacancies on the surface is obtained; a metal precursor solution is dripped into the metal oxide with defect vacancies on the surface, mixed evenly, subjected to ultrasonic treatment for 4-6 hours, and then subjected to secondary calcination to obtain a metal spontaneous deposition catalyst with a single metal element evenly distributed on the surface of the metal oxide; wherein the volume ratio of the metal oxide with defect vacancies on the surface to the metal precursor solution is 1:0.5-2.5; and the mass of the metal element in the metal precursor solution accounts for 0.01-10% of the mass of the metal oxide with defect vacancies on the surface.

[0032] In an embodiment of the present invention, the preparation process of the third catalyst is as follows: after evenly mixing the alkaline metal oxide and the molecular sieve in a weight ratio of 0.1-10, the mixture is pressed into tablets and granulated; the solid obtained by the pressing and granulation is placed in a reducing atmosphere calcining furnace, and calcined at 0.5-1Mpa and 150-350°C for 1-10h; and the third catalyst is obtained.

[0033] In order to enable those skilled in the art to understand the present application more clearly, a synthesis process of aromatic chemicals described in the present application is now described in detail through the following examples.

[0034] Example 1 This example uses the first catalyst to explore the synthesis process of aromatic chemicals, as follows: Step 1: Preparation of LaFeO3 perovskite matrix: 8.08g of lanthanum nitrate hexahydrate and 7.55g of ferric nitrate nonahydrate were added to 50ml of deionized water at room temperature, and stirred rapidly until completely dissolved. Then 23.1g of anhydrous citric acid was added. At this time, the solution was stirred at 550r / min, heated at 80°C, and ammonium carbonate solution was gradually added dropwise to adjust the pH value to about 7. The excess liquid was evaporated, stirred to form a viscous gel, and the magnet was taken out; then kept in an oven at 110°C for 24h, naturally cooled and ground to obtain a LaFeO3 precursor. The dried precursor perovskite was roasted in a muffle furnace at 450°C for 2 hours to obtain a LaFeO3 perovskite matrix; Step 2: Composite of LaFeO3 perovskite matrix and H-ZSM5: The obtained LaFeO3 perovskite matrix was mixed with nano-H-ZSM5 in a mass ratio of 1:1 and placed in a 10% reducing gas / N2 mixed gas, and reduced at 300°C, 0.5 MPa pressure, and 500 ml / min flow rate for 2 h.

[0035] Step 3: Using the LaFeO3-H-ZSM5 composite catalyst synthesized above, the synthesis process of aromatic chemicals was explored. The process is as follows: A mixed gas with a volume ratio of hydrogen to CO2 of 3 and different concentrations of CO (0%, 4%, 8%, and 12% by volume) was used as the raw gas. Catalytic conversion was carried out at a space velocity of 600 mL / h·gcat, a pressure of 3 MPa, and a temperature of 300°C.

[0036] Figure 1 The XRD patterns of LaFeO3 catalysts at different CO doping concentrations are shown in Figure 2. Figure 1 As shown in the figure, with the increase of CO doping content or the increase of reaction time, the perovskite phase structure of LaFeO3 catalyst has not changed significantly, which shows that the addition of CO atmosphere has no structural effect on the catalyst and the perovskite has a stable structure. This shows that it is reasonable and sustainable to add CO to the catalytic system on LaFeO3 to improve CO2 conversion rate and CO selectivity.

[0037] Figure 2 The concentration changes of oxygen vacancies on the surface of LaFeO3 catalyst under different CO doping concentrations are shown, among which, Figure 2 (a) shows the surface oxygen vacancy concentration of fresh LaFeOx metal oxide, Figure 2 (b) shows the oxygen vacancy concentration on the surface of metal oxides after the reaction without adding CO to the raw gas. Figure 2 (c) shows that the addition of 4% CO in the reaction feed gas significantly increases the concentration of oxygen vacancies on the metal oxide surface. Figure 2 (d) shows that the oxygen vacancies combine with hydrogen and the generated water is detected, proving the existence of oxygen vacancies; Figure 2 As shown in the figure, the addition of CO in the reaction atmosphere (H2 and CO2) can greatly enhance the oxygen vacancy concentration on the surface of the catalyst LaFeO3. This also explains why the addition of CO enhances the conversion rate of the catalyst CO2. When too much CO is added, the balance of the reaction system deviates in the opposite direction due to the increase of products, which is not conducive to the conversion of CO2.

[0038] Table 1 lists the reaction results of CO2 hydrogenation reaction of LaFeO3 perovskite matrix and nano H-ZSM5 composite catalyst in feed gas with different CO concentrations. It can be seen that when the CO concentration in the feed gas is 4%, the CO2 conversion rate and aromatics selectivity are both optimal.

[0039] Table 1 Carbon dioxide conversion and selectivity of mixed aromatic chemicals

[0040] This example further explores the effect of the space velocity of the reaction raw gas on the selectivity of aromatic chemicals, as follows: A mixed gas formed by a hydrogen to CO2 volume ratio of 3 and 4% CO was added as the raw gas. Under the conditions of pressure of 3 MPa and temperature of 300 °C, the reaction space velocity was adjusted to 600, 1000, 1200, 1500, 1800, and 2400 mL / h·gcat, respectively, and multiple catalytic conversions were carried out with a reaction time of 24 h.

[0041] The CO added to the reaction system in the early stage of the reaction significantly improves the reaction activity of the catalyst, and the reaction space velocity is further adjusted in the reaction conditions. Figure 3 The effect of space velocity on the synthesis process of aromatic chemicals provided by the embodiment of the present invention is shown, such as Figure 3 As shown, with the increase of reaction space velocity, the data showed a regular decrease in conversion rate, and no obvious catalyst deactivation and changes in product distribution occurred.

[0042] The present invention further explores the effect of pressure changes on the selectivity of aromatic chemicals during the reaction process, as follows: A mixed gas formed by a hydrogen to CO2 volume ratio of 3 and 4% CO was added as the raw gas. The reaction temperature was 300°C and the reaction space velocity was 600 mL / h·gcat. The reaction pressure was adjusted to 2, 3, 4, 5, and 6 MPa, respectively, and multiple catalytic conversions were carried out. The reaction time was 24 h.

[0043] The CO added to the reaction system in the early stage of the reaction significantly improves the reaction activity of the catalyst, and the pressure in the reaction conditions is further adjusted. Figure 4 The effect of pressure on the aromatic hydrocarbon chemical synthesis process provided by the embodiment of the present invention is shown. Figure 4 As shown, with the increase of pressure, the data showed a regular increase in conversion rate, and no obvious change in product distribution occurred.

[0044] Example 2 This example uses the second catalyst to explore the synthesis process of aromatic chemicals, as follows: Step 1: Preparation of bimetallic oxide supports with abundant oxygen vacancies and metal defect sites on the surface (1) Weigh 13.98 g of zinc nitrate hexahydrate and 37.61 g of chromium nitrate nonahydrate and dissolve them in beaker A containing 1000 g of deionized water. Then place beaker A in a heatable magnetic stirrer. Heat the magnetic stirrer to 60°C and continue stirring for 60 min until the solid salt is completely dissolved.

[0045] (2) Prepare a beaker containing 500 g of deionized water, referred to as Beaker B. Add 48.05 g of ammonium carbonate to Beaker B. Place Beaker B on a heated magnetic stirrer at 45°C and stir thoroughly until the solid is completely dissolved.

[0046] (3) Prepare a three-necked flask, slowly add the solutions in beaker A and beaker B into the three-necked flask, maintain the temperature of the mixed solution at 70-100°C, and control the pH of the mixed solution in the three-necked flask to be between 5.5 and 8.5 by adjusting the rate of adding the solution in beaker A or B. Stir continuously during the whole process; (4) After mixing is completed, stirring is continued and nitrogen is introduced to allow the mixture to crystallize for 8 hours under a nitrogen atmosphere.

[0047] (5) After crystallization in step 4, carbon nanotubes are added to the mixed solution in a ratio of 1:0.01. At the same time, the heating is turned off and stirring is continued. The mixture is cooled naturally and stirred for 2 to 6 hours until it reaches room temperature.

[0048] (6) The obtained metal oxide precursor was filtered and washed three times, dried at 110°C, and calcined at 450°C for 2 h under air atmosphere at a rate of 5°C / min. A ZnCrOx bimetallic oxide carrier with abundant oxygen vacancies and metal defect sites on the surface was obtained.

[0049] Step 2: The metal falls into place spontaneously (1) A certain amount of ferric nitrate nonahydrate was dissolved in deionized water and reacted under a microwave with a power of 300 W for 2 min to 5 min to prepare a uniformly dissolved single metal atom stock solution, in which the mass ratio of Fe to metal oxide was 0.03:1; (2) The ZnCrOx bimetallic oxide carrier prepared in step 1 was uniformly mixed with the single atom stock solution, and then subjected to ultrasonic treatment at a power of 600 W, a frequency of 40 kHz, and an ultrasonic time of 4 h. After the ultrasonic treatment, the temperature was raised to 350 °C at a rate of 1 °C / min in an air atmosphere and calcined for 2 h. A Fe metal spontaneously falling catalyst was obtained.

[0050] Step 3: Using the Fe metal spontaneous ablation catalyst (second catalyst) synthesized above, the synthesis process of aromatic chemicals was explored. The process is as follows: A mixed gas with a volume ratio of hydrogen to CO2 of 3 and different concentrations of CO (0%, 4%, 8%, and 12% by volume) was used as the raw gas. Catalytic conversion was carried out at a space velocity of 600 mL / h·gcat, a pressure of 3 MPa, and a temperature of 300°C.

[0051] Table 2 lists the reaction results of CO2 hydrogenation reaction over Fe metal spontaneously falling catalyst in feed gas with different CO concentrations. It can be seen that when the CO concentration in the feed gas is 4%, the CO2 conversion rate and aromatics selectivity are both optimal.

[0052] Table 2 Carbon dioxide conversion and selectivity of mixed aromatic chemicals

[0053] Example 3 This example uses the third catalyst to explore the synthesis process of aromatic chemicals, as follows: Step 1: Preparation of ZnCrO x Bimetallic Oxide (1) Weigh 13.98 g of zinc nitrate hexahydrate and 37.61 g of chromium nitrate nonahydrate and dissolve them in beaker A containing 1000 g of deionized water. Then place beaker A in a heatable magnetic stirrer. Heat the magnetic stirrer to 60°C and continue stirring for 60 min until the solid salt is completely dissolved.

[0054] (2) Prepare a beaker containing 500 g of deionized water, referred to as Beaker B. Add 48.05 g of ammonium carbonate to Beaker B. Place Beaker B on a heated magnetic stirrer at 45°C and stir thoroughly until the solid is completely dissolved.

[0055] (3) Prepare a three-necked flask, slowly add the solutions in beaker A and beaker B into the three-necked flask, maintain the temperature of the mixed solution at 70-100°C, and control the pH of the mixed solution in the three-necked flask to be between 5.5 and 8.5 by adjusting the rate of adding the solution in beaker A or B. Stir continuously during the whole process; (4) After mixing is completed, stirring is continued and nitrogen is introduced to allow the mixture to crystallize for 8 hours under a nitrogen atmosphere.

[0056] (5) The obtained metal oxide precursor was filtered and washed three times, dried at 110°C, and calcined at 450°C at a rate of 5°C / min for 2h in an air atmosphere. 54g ZnCrO was obtained. x Bimetallic oxide support.

[0057] Step 2: Preparation of surface-regular hydrogen-type ZSM-5 molecular sieve (1) Weigh the ZnCrO prepared in step 1x The same weight of nano ZSM-5 molecular sieve was stirred with 540 g of 2 mol / L ammonium nitrate solution at 80° C. for 2 h, and the solid was filtered out.

[0058] (2) The obtained solid was mixed with 800 g of 3 mol / L tetrapropylammonium hydroxide alkaline solution at 50° C. and stirred for 8 h. The mixture was filtered and the filter cake was collected and washed to neutrality.

[0059] (3) The obtained neutral filter cake was dried at 100°C for 12 hours; (4) The dried sample was calcined in a muffle furnace at 600 °C with a heating rate of 5 °C / min for 10 h.

[0060] Step 3: ZSM-5 molecular sieve and ZnCrO x Double metal oxide composite ZnCrO x After being mixed and ground with hydrogen-type ZSM-5 using a sand mill for 1 hour, the sample was pressed into tablets and granulated. The obtained sample was loaded into a special reduction roasting furnace, the roasting furnace temperature was increased to 380 °C at a rate of 10 °C / min, the pressure in the roasting furnace was increased to 1 MPa, and carbon monoxide gas was introduced into the roasting furnace at a flow rate of 50 ml / min. After the reducing gas carbon monoxide acted for 10 hours, the roasting furnace automatically released the pressure and formed a negative pressure of 0.1 MPa in the furnace. After continuing to roast under negative pressure conditions for 1 hour, the third catalyst (acid-base heterojunction catalyst) was synthesized.

[0061] Step 4: Using the third catalyst (acid-base heterojunction catalyst) synthesized above, the synthesis process of aromatic chemicals is explored. The process is as follows: A mixed gas with a volume ratio of hydrogen to CO2 of 3 and different concentrations of CO (0%, 4%, 8%, and 12% by volume) was used as the raw gas. Catalytic conversion was carried out at a space velocity of 600 mL / h·gcat, a pressure of 3 MPa, and a temperature of 300°C.

[0062] Table 3 lists the reaction results of the third catalyst (acid-base heterojunction catalyst) in the CO2 hydrogenation reaction in the feed gas containing different CO concentrations. It can be seen that when the CO concentration in the feed gas is 4%, the CO2 conversion rate and aromatics selectivity are both optimal.

[0063] Table 3 Carbon dioxide conversion and selectivity of mixed aromatic chemicals

[0064] Example 4 This embodiment uses the third catalyst (ZnCrO xThe synthesis process of aromatic chemicals was studied using a bifunctional microsphere catalyst prepared by combining with H-ZSM5, as follows: Step 1: ZnCrO x Preparation of composite bifunctional microsphere catalyst with H-ZSM5 (a) Preparation of phosphate ceramic glue modified with nano-yttria Add 338 g of 85% industrial phosphoric acid, 68 g of 320 mesh aluminum hydroxide powder, 6 g of silicic acid, 12 g of light magnesium oxide, 0.5 g of nano yttrium oxide, and 1000 g of pure water into a beaker in sequence, and slowly heat to 150°C while stirring until the solution becomes transparent to obtain nano yttrium oxide-modified phosphate ceramic glue.

[0065] (b) Weigh 1122.5 g of ZnCrOx spinel oxide prepared by co-precipitation and 1000 g of H-ZSM5 molecular sieve and mix them evenly; The components of step (a) and step (b) are mixed, stirred and heated to 80°C until the mixture becomes a gel state, and the gel component is dried at 120°C overnight.

[0066] (d) The powder obtained in step (c) is calcined in a special high-pressure reduction calcination furnace, the pressure is 0.5 MPa, the reducing gas is hydrogen, the flow rate is 100 ml / min, and the calcination is performed for 5 h.

[0067] (e) mixing 10 parts of the powder obtained in step (d) with 30 parts of a binder and an appropriate amount of water in a stirring tank; the binder is composed of a silica sol with a mass concentration of 45% and an aluminum hydrosol with a mass concentration of 10%, and the dry weight ratio of the two components in the binder is 1:0.25; then adding 20 dry weight parts of kaolin to the mixed suspension, stirring to obtain a suspension emulsion with a solid weight content of 35%; adjusting the pH of the suspension emulsion to 3.5 to make it gel-like; (f) granulating and drying the gel by a spray granulation method, with the inlet temperature of the granulation tower being 350°C and the outlet temperature being 200°C to prepare solid microspheres; (g) calcining the solid microspheres in the range of 300-450°C to prepare bifunctional microsphere catalysts for CO2 / CO1+H2 to produce aromatic chemicals / liquid fuels; Step 2: The third catalyst (ZnCrO x The bifunctional microsphere catalyst prepared by compounding with H-ZSM5) was used to explore the synthesis process of aromatic chemicals. The process is as follows: A mixed gas with a volume ratio of hydrogen to CO2 of 3 and different concentrations of CO (0%, 4%, 8%, and 12% by volume) was used as the raw gas. Catalytic conversion was carried out at a space velocity of 600 mL / h·gcat, a pressure of 3 MPa, and a temperature of 300°C.

[0068] Table 4 lists the third catalyst (ZnCrO x The reaction results of CO2 hydrogenation reaction in feed gas with different CO concentrations using bifunctional microsphere catalyst prepared by composite with H-ZSM5. It can be seen that when the CO concentration in the feed gas is 4%, the CO2 conversion rate and aromatics selectivity are both optimal.

[0069] Table 4 Carbon dioxide conversion and selectivity of mixed aromatic chemicals

[0070] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0071] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0072] The above is a detailed introduction to the aromatic hydrocarbon chemical synthesis process provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A process for synthesizing aromatic chemicals, characterized in that: The synthesis process comprises: A certain amount of CO is added to a mixed gas of H2 and CO2 in a volume ratio of 1:2-5 as a reaction raw material gas, and under the action of a first catalyst, a second catalyst or a third catalyst, the reaction raw material feed space velocity is controlled to be 500-2400 mL / h·gcat, the reaction temperature is 300-550°C, and the reaction pressure is 2-6 MPa, and catalytic conversion is performed to obtain aromatic chemicals; Wherein, the first catalyst is formed by combining a lanthanum perovskite oxide with a chemical formula of ABO3 and a hydrogen-type molecular sieve with two-dimensional or three-dimensional pores; the A is selected from lanthanum or cerium, the B is selected from transition metals, or the B is composed of transition metals and noble metals, the mass fraction of the noble metal is 0.00wt% to 4wt%, the molar ratio of A to B is 0.8:1 to 1:0.8, the transition metal is chromium, manganese, iron, cobalt or nickel, and the noble metal is ruthenium, rhodium, palladium, iridium or platinum; The second catalyst is composed of a metal oxide with defect vacancies on the surface and a single metal atom, wherein the single metal atom is uniformly loaded on the surface of the metal oxide in the form of chemical bonds to form a regular surface atomic arrangement; the metal oxide is MnO x 、ZrO、MoO、ZnZrO x 、MnCrO x , ZnMoO or ZnCr2O x ; The single metal atom is Zn, Cu, Cr, Mn, Pd, Zr, Al, Mo, Ge, In, Ni, Au, Fe or Y; the mass of the single metal atom accounts for 0.01 to 10% of the mass of the metal oxide; The third catalyst is composed of an alkaline metal oxide and a molecular sieve in a weight ratio of 0.1:10, and the alkaline metal oxide includes MnO, CrO, ZrO, GeO, NiO, ZnCrO x 、ZnPdO x or ZnMoO x .

2. The process for synthesizing aromatic chemicals according to claim 1, characterized in that: In the reaction raw material gas, the volume proportion of CO is 3-12%.

3. The process for synthesizing aromatic chemicals according to claim 2, characterized in that: In the reaction raw gas, the volume proportion of CO is 4%.

4. The process for synthesizing aromatic chemicals according to claim 1, characterized in that: The reaction raw material feed space velocity is 600 mL / h·gcat, the reaction temperature is 300° C., and the reaction pressure is 3 Mpa.

5. The process for synthesizing aromatic chemicals according to claim 1, characterized in that: The molecular sieve is selected from H-ZSM5, ZSM-5, ZSM-11 or ZSM-48.

6. The process for synthesizing aromatic chemicals according to claim 1, characterized in that: The ABO3 is LaFeO3, LaCoO3, LaNiO3, LaMnO3 or LaFe 0.97 Pd 0.03 O3.

7. The process for synthesizing aromatic chemicals according to claim 6, characterized in that: The ABO3 is LaFeO3.

8. The process for synthesizing aromatic chemicals according to claim 1, characterized in that: The molecular sieve is H-ZSM5, and the ABO3 is LaFeO3; The selectivity of the aromatic chemicals is not less than 70%, and the C1 conversion rate is greater than 30%.

9. The process for synthesizing aromatic chemicals according to claim 1, characterized in that: The aromatic chemicals converted by the catalytic conversion are mainly para-xylene and benzene.

10. The process for synthesizing aromatic chemicals according to claim 9, characterized in that: Paraxylene accounts for more than 80% of the aromatic chemicals.

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