CN113651671A - Method for simultaneously preparing propylene and synthesis gas by carbon dioxide propane oxide hydrodehydrogenation - Google Patents

Method for simultaneously preparing propylene and synthesis gas by carbon dioxide propane oxide hydrodehydrogenation Download PDF

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CN113651671A
CN113651671A CN202110861257.6A CN202110861257A CN113651671A CN 113651671 A CN113651671 A CN 113651671A CN 202110861257 A CN202110861257 A CN 202110861257A CN 113651671 A CN113651671 A CN 113651671A
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propane
carbon dioxide
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propylene
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CN113651671B (en
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刘忠文
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Shaanxi Normal University
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    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/42—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with a hydrogen acceptor
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    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
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    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0227—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step
    • C01B2203/0238—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being a carbon dioxide reforming step
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Abstract

The invention discloses a method for preparing propylene and synthesis gas simultaneously by oxidizing propane with carbon dioxide and dehydrogenating the propane in the presence of hydrogen, which is characterized in that carbon dioxide gas and hydrogen are simultaneously introduced in the process of preparing propylene by directly dehydrogenating propane, and the volume ratio of the introduced carbon dioxide gas to the introduced hydrogen to the propane is 0.5-5.0: 0.5-3.0: 1.0. On one hand, the method of the invention utilizes the carbon dioxide weak oxidant introduced into the reaction system to relieve the thermodynamic equilibrium limitation of direct dehydrogenation of propane, improves the conversion rate of propane, and simultaneously introduces H into the reaction system2Carbon deposit is inhibited, and the service life of the catalyst is prolonged; on the other hand, the aim of simultaneously preparing propylene and synthesis gas is achieved by utilizing a propane and carbon dioxide reforming reaction (CRP), a reverse water gas shift Reaction (RWGS) and a coupling effect of the CRP and the RWGS.

Description

Method for simultaneously preparing propylene and synthesis gas by carbon dioxide propane oxide hydrodehydrogenation
Technical Field
The invention belongs to the technical field of propylene preparation by propane dehydrogenation, and particularly relates to a method for preparing propylene and synthesis gas by simultaneously oxidizing propane with carbon dioxide and dehydrogenating the propane in hydrogen.
Background
Propylene is second only to ethylene, an important basic raw material used in the petrochemical industry, and the position in the modern petrochemical industry is very important. The downstream industrial chain of propylene is very diverse, mainly used for producing polypropylene, and also acrylic acid, propylene oxide, acetone and the like. In recent years, with the rapid increase in the downstream product demand of propylene, the consumption of propylene has also been steadily increasing in our country. For a long time, propylene is mainly produced by processes such as steam thermal cracking, catalytic thermal cracking and the like of naphtha, and the like, and has the problems of high equipment investment, low raw material processing capacity, high energy consumption and the like. The propane dehydrogenation process is a technological approach for preparing propylene with high added value and short market by dehydrogenating propane which is cheap and easy to obtain, and simultaneously solves two important problems of large propylene demand gap and low comprehensive utilization rate of propane, thereby having great significance for optimizing the energy industrial structure.
According to the dehydrogenation mode, the dehydrogenation of propane to propylene mainly comprises two routes of direct dehydrogenation and oxidative dehydrogenation. At present, although the direct dehydrogenation of propane to Propylene (PDH) has been industrially applied and the related technologies become more and more mature, due to the characteristics of strong endothermic reaction, thermodynamic equilibrium limitation exists, and the conversion rate with industrial application value can be achieved only at higher reaction temperature. This results in two disadvantages, namely: the energy consumption is increased and the carbon deposit of the catalyst is inactivated seriously due to higher reaction temperature. In contrast to direct dehydrogenation, for a system for preparing propylene by oxidative dehydrogenation of propane, molecular oxygen is added as an oxidant to oxidize hydrogen into water and convert the original endothermic reaction into an exothermic reaction, so that the preparation of propylene by oxidative dehydrogenation of molecular oxygen by propane does not have the problem of thermodynamic equilibrium limitation and can be carried out at a lower temperature. However, molecular oxygen inevitably oxidizes propane and product propylene to CO simultaneously with oxidizing hydrogen2And water, the selectivity of the target product is reduced. Therefore, although the dehydrogenation of propylene by molecular oxygen oxidation has many advantages such as no thermodynamic equilibrium limitation, low energy consumption and the like, and long-term research and exploration are carried out, the problem of low propylene yield still cannot be solved, and the industrialization cannot be realized until now. Adding CO compared with molecular oxygen strong oxidant2、N2The oxidative dehydrogenation of weak oxidants such as O and the like can relieve the thermodynamic equilibrium limitation of direct dehydrogenation to a certain extent while avoiding the problem of deep oxidation of molecular oxygen, so people can shift the eyes to CO with weak oxidizability2、N2Dehydrogenation of propane oxide such as O.
CO2Is a well-known greenhouse gas, CO, in the past half century2Result in significant global gasChange of temperature, the thermodynamically stable and kinetically inert CO2The catalytic activation is used as a weak oxidant, so that the problems of deep oxidation and the like in the dehydrogenation of propane by oxidizing oxygen are solved, the thermodynamic equilibrium conversion rate of direct dehydrogenation is improved, and the greenhouse gas CO can be realized2Has received wide attention because of resource utilization. Despite CO2Dehydrogenation of propane oxide to propylene (CO)2-ODP) has the advantages of high selectivity, environmental protection, energy conservation and the like, can overcome the problems of high investment, high energy consumption, lower raw material processing capacity and the like of PDH process equipment, and can realize greenhouse gas CO2The resource utilization is expected to become an energy-saving and environment-friendly green synthesis process, but CO2The molecules are very stable and difficult to activate, the oxidability is not strong, and the existing catalyst faces the challenging problems of low activity, rapid inactivation and the like.
As described above, although the production of propylene by dehydrogenation of propane is becoming important in alleviating the contradiction between supply and demand of propylene and in achieving high-value utilization of propane, and direct dehydrogenation of propane has been put to industrial use, direct dehydrogenation, oxidative dehydrogenation by molecular oxygen, and CO have been carried out in the past2The reaction approaches of oxidative dehydrogenation of weak oxidants and the like have common problems of low propylene yield, poor catalyst stability and the like.
Disclosure of Invention
The invention aims to provide a method for preparing propylene and synthesis gas simultaneously by the oxydehydrogenation of propane by carbon dioxide, which not only improves the conversion rate of propane and the service life of a catalyst, but also realizes the purpose of preparing propylene and synthesis gas simultaneously.
Aiming at the purposes, the method for simultaneously preparing the propylene and the synthesis gas by the carbon dioxide propane oxide hydrodehydrogenation adopted by the invention comprises the following steps: in the process of preparing propylene by direct dehydrogenation of propane, carbon dioxide gas and hydrogen are simultaneously introduced.
In the method, the volume ratio of the introduced carbon dioxide gas, the introduced hydrogen gas and the introduced propane is 0.5-5.0: 0.5-3.0: 1.0, and the volume ratio of the introduced carbon dioxide gas, the introduced hydrogen gas and the introduced propane is preferably 1-2: 1-1.5: 1.
In the above process, the catalyst used is preferably Pt-SnO2/Al2O3Or Pt-SnO2-CeO2/Al2O3。
In the above catalyst, it is preferable that the amount of Pt supported is 0.1% to 1.0% and SnO is contained in an amount of 100% by mass of the catalyst2The loading amount of the CeO is 0.5 to 5.0 percent2The loading amount of the catalyst is 0.1-5.0%.
In the above method, the reaction temperature is preferably 500 to 650 ℃ and the operation pressure is preferably 0.05 to 0.15 MPa.
The invention firstly proposes that CO is introduced into a direct propane dehydrogenation reaction system at the same time2And H2For short CO2Oxidative propane hydrodehydrogenation (CO)2-H2-PDH) reaction. CO 22-H2Thermodynamic equilibrium composition of propane and CO in a PDH reaction system2The percentage of (A) decreases with increasing temperature, indicating an increase in temperature, favoring propane and CO2This is understood to mean that the temperature increase favors the forward progress of the reaction of PDH and RWGS. At the same time, CO2-H2-H in PDH reaction System2The percentage of (d) increases with increasing temperature, indicating that the hydrogen evolved from the PDH reaction is not completely consumed by the RWGS reaction. That is, CO2-H2H addition to the PDH System2Not only is not consumed, but also H is generated2And generate H2The amount of (a) increases with increasing temperature. Comparative CO2-H2-PDH and CO2-propane and CO at the same temperature of ODP2In percent, CO can be found2-H2-PDH for propane and CO2The percentage content is less than CO2ODP, description of CO2-H2H in PDH2Contributing to both propane and CO2The transformation of (3). CO 22-H2-PDH thermodynamic equilibrium propane conversion higher than PDH, whereas thermodynamic equilibrium CO2The conversion is higher than RWGS, due to, on the one hand, the addition of H2The balance of the RWGS reaction is favorably moved to the positive direction, and the positive direction of propane dehydrogenation is pulled to be carried out; on the other hand, CO2And propane can be generated to CO and H2The reforming reaction of (a) finally favors propane simultaneouslyAnd CO2Without consuming H while producing propylene2And the synthesis gas is enriched. Thus, in one aspect, the process of the invention utilizes H introduced into the reaction system2Inhibiting the carbon deposition and inactivation of the catalyst; on the other hand, by reverse water gas shift Reaction (RWGS), propane and carbon dioxide reforming reaction (CRP) and coupling action thereof, the thermodynamic equilibrium limit of propane hydrodehydrogenation is relieved, and CO is increased2The conversion rate, the stability of the catalyst and the yield of propylene are improved, and meanwhile, the synthesis gas is enriched.
The invention has the following beneficial effects:
on one hand, the method of the invention utilizes the carbon dioxide weak oxidant introduced into the reaction system to relieve the thermodynamic equilibrium limitation of direct dehydrogenation of propane, improves the conversion rate of propane, and simultaneously introduces H into the reaction system2Carbon deposit is inhibited, and the service life of the catalyst is prolonged; on the other hand, the aim of simultaneously preparing propylene and synthesis gas is achieved by utilizing a propane and carbon dioxide reforming reaction (CRP), a reverse water gas shift Reaction (RWGS) and a coupling effect of the CRP and the RWGS.
Drawings
FIG. 1 shows 1 wt.% Pt-1.2 wt.% SnO in different reaction atmospheres in example 12/Al2O3Propane conversion and propylene selectivity profile for catalytic propane dehydrogenation.
FIG. 2 shows 1 wt.% Pt to 1.2 wt.% SnO in different reaction atmospheres in example 12/Al2O3Propylene yield from catalytic propane dehydrogenation.
FIG. 3 shows 1 wt.% Pt-1.2 wt.% SnO in different reaction atmospheres in example 12/Al2O3CO catalytic dehydrogenation of propane2And (4) a conversion rate chart.
FIG. 4 is 1 wt.% Pt-1.2 wt.% SnO2/Al2O3Catalysis of CO2ODP (curve a) and CO2-H2TG curve of the catalyst after 100min reaction of PDH (curve b).
FIG. 5 is 1 wt.% Pt-1.2 wt.% SnO2/Al2O3Catalysis of CO2ODP (curve a) and CO2-H2Of the catalyst after 100min of reaction with PDH (curve b)DSC curve.
FIG. 6 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 22-3wt.％CeO2/Al2O3Catalysis of CO2-H2Propane conversion and propylene selectivity profile for PDH.
FIG. 7 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 22-3wt.％CeO2/Al2O3Catalysis of CO2-H2Propylene yield plot of PDH.
FIG. 8 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 22-3wt.％CeO2/Al2O3Catalysis of CO2-H2CO of PDH2Conversion and H2/CO、H2/(CO+CO2) Figure (a).
FIG. 9 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 22-3wt.％CeO2/Al2O3Catalysis of CO2-H2H of-PDH2And (4) a conversion rate chart.
FIG. 10 is a graph of 1 wt.% Pt to 1.2 wt.% SnO for different reaction times in example 32-3wt.％CeO2/Al2O3And 1 wt.% Pt-1.2 wt.% SnO2/Al2O3Catalysis of CO2-H2Propane conversion and propylene selectivity profile for PDH.
FIG. 11 is a graph of 1 wt.% Pt to 1.2 wt.% SnO for different reaction times in example 32-3wt.％CeO2/Al2O3And 1 wt.% Pt-1.2 wt.% SnO2/Al2O3Catalysis of CO2-H2Propane yield plot of PDH.
FIG. 12 is a graph of 1 wt.% Pt to 1.2 wt.% SnO for different reaction times in example 32-3wt.％CeO2/Al2O3And 1 wt.% Pt-1.2 wt.% SnO2/Al2O3Catalysis of CO2-H2CO of PDH2And (4) a conversion rate chart.
FIG. 13 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 42-3wt.％CeO2/Al2O3Regenerated catalytic CO2-H2Propane conversion and propylene selectivity profile for PDH.
FIG. 14 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 42-3wt.％CeO2/Al2O3Regenerated catalytic CO2-H2Propane yield plot of PDH.
FIG. 15 is a graph of 1 wt.% Pt to 1.2 wt.% SnO in example 42-3wt.％CeO2/Al2O3Regenerated catalytic CO2-H2CO of PDH2And (4) a conversion rate chart.
Detailed Description
The invention will be further described in detail with reference to the following figures and examples, but the scope of the invention is not limited to these examples.
Pt-SnO used in the following examples2/Al2O3The catalyst is H2PtCl6·6H2O and SnCl2·2H2O as Pt and SnO2The precursor is prepared by adopting an immersion method, wherein the theoretical loading of Pt is 1 wt.%, and the theoretical loading of Sn is 0.6 wt.%, 1.2 wt.%, 1.8 wt.% and 2.4 wt.%, respectively. The preparation method comprises the following specific steps: h is to be2PtCl6·6H2O and SnCl2·2H2Dissolving O in ethanol to make the volume of the solution equal to the predetermined Al2O3Pore volume of (a). Then mixing the solution with Al2O3The powders were mixed and allowed to stand at room temperature for 12h to complete the equal volume impregnation. Then, the sample is dried in a blast oven at 110 ℃ for 10 hours and roasted in a muffle furnace at 600 ℃ for 4 hours to obtain different SnO2Content of Pt-SnO2/Al2O3A catalyst.
Pt-SnO used in the following examples2-CeO2/Al2O3The catalyst is H2PtCl6·6H2O、SnCl2·2H2O and Ce (NO)3)3·6H2O as Pt or SnO2And CeO2The precursor is prepared by adopting an impregnation method, wherein the theoretical loading capacity of Pt is 1 wt.%, the theoretical loading capacity of Sn is 1.2 wt.%, and the theoretical loading capacity of Ce is 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.% and 5 wt.%, respectively. Tool bodyThe preparation method comprises the following steps: h is to be2PtCl6·6H2O、SnCl2·2H2O and Ce (NO)3)3·6H2Dissolving O in ethanol to make the volume of the solution equal to the predetermined Al2O3Pore volume of (a). Then mixing the solution with Al2O3The powders were mixed and allowed to stand at room temperature for 12h to complete the equal volume impregnation. Then, the sample is dried in a blast oven at 110 ℃ for 10 hours and roasted in a muffle furnace at 600 ℃ for 4 hours to obtain Pt-SnO2-CeO2/Al2O3A catalyst.
In the following examples, the product was analyzed on-line by a GC-9560 gas chromatograph manufactured by huaai chromatography technologies ltd (shanghai), which is equipped with a TCD thermal conductivity detector and a FID hydrogen flame detector. The main product of the reaction is CO2、CO、CH4、C2H6、C2H4、C3H8、C3H6、H2. Using Ar as chromatographic column carrier gas, TCD for CO analysis2、CO、H2Content of (1), FID is CH analysis4、C2H6、C2H8、C3H6、C3H8The content of (a). The propane conversion and the selectivity of each main product were calculated by the internal standard method.
Example 1
500mg of 40-60 meshes of 1 wt.% Pt-1.2 wt.% SnO2/Al2O3The catalyst was packed in a quartz tube (length 40cm, inner diameter 6mm) of a mini fixed bed reactor, and H was fed into the reactor at a total gas flow rate of 50mL/min2And He, H2The volume ratio of the He and the reaction gas is 1:9, the temperature is raised to 500 ℃ from room temperature at the temperature raising rate of 5 ℃/min, the He is switched after reduction is carried out for 1h, the temperature is continuously raised to 600 ℃, and then the reaction gas and the argon gas are switched (the argon gas is used as an internal standard gas and is used for chromatographic quantitative analysis). The total flow of gas is 50mL/min, the operating pressure is 0.1MPa, and after the gas is stable, sampling analysis is started. Wherein the reaction gas is a mixed gas (volume ratio H) of hydrogen, helium and propane2/He/C3H81:1:1), orMixed gas of carbon dioxide, helium and propane (volume ratio of CO)2/He/C3H81:1:1), or a mixture of carbon dioxide with hydrogen and propane (volume ratio CO)2/H2/C3H81.5:0.5:1 or CO2/H2/C3H8＝1:1:1)，C3H8The volume ratio to Ar was 8: 1.
FIGS. 1 to 3 show 1 wt.% Pt and 1.2 wt.% SnO in different reaction atmospheres in sequence2/Al2O3Propane conversion and propylene selectivity, propylene yield, CO for catalytic propane dehydrogenation2Conversion yield plot wherein curve a is H2/He/C3H81:1:1 as reaction gas, curve b is CO2/He/C3H81:1:1 as reaction gas, curve c is CO2/H2/C3H81.5:0.5:1 as reaction gas, curve d is CO2/H2/C3H81:1:1 as reaction gas. Under the same catalyst, reaction conditions and total gas flow, it can be seen from the figure that under a hydrogen atmosphere (curve a), i.e. propane is dehydrogenated hydrodynamically, the initial conversion of propane at a reaction Time (TOS) of 13min is 35% and the propylene selectivity is 90%; after 85min of reaction, the propane conversion decreased slightly, propylene selectivity was essentially unchanged, and propylene yield decreased slightly from the initial 32% (TOS 13min) to 29% (TOS 85min), consistent with the results reported in the literature for Pt-based catalysts. In CO2Carried out under an atmosphere, i.e. CO2ODP (curve b), although the initial conversion of propane at TOS 13min (37.5%) is slightly higher than that at propane hydrodehydrogenation (35%), the propane conversion decreases rapidly with increasing TOS, and the conversion of propane at the end of the reaction (TOS 85min) is only 4.4%. Thus, in contrast to propane hydrodehydrogenation, Pt-based catalysts are in CO2Rapid deactivation during the ODP reaction. From the propylene selectivity, the propylene selectivity is maintained at about 92 percent within 85min, and is similar to the result of the dehydrogenating of propane in the presence of hydrogen; CO 22The propylene yield of the-ODP decreases rapidly with the prolongation of TOS, showing the characteristic of rapid deactivation. If CO in the reaction process is analyzed2The conversion rate can be increasedNow, it also showed a rapid decrease from 22% at TOS of 13min to 6% at the end of the reaction. Thus, CO2Rapid inactivation of ODP and its activation to convert CO2The ability of (A) to (B) decreases as the reaction proceeds. If at CO2A small amount of hydrogen was introduced into the ODP reaction system (curve c), and CO was significantly suppressed2Rapid deactivation of the catalyst during the ODP reaction, with CO during the entire reaction2The conversion of (a) stabilized at about 25%. If the amount of hydrogen fed is further increased (curve d), the initial conversion of propane is increased and at the same time the stability of the catalyst is significantly improved (after 85min of reaction, the conversion of propane is reduced from 44% at TOS of 13min to 30%, the yield of propylene is reduced from 40% to 28%, CO is reduced from 28%, and2the conversion rate is kept above 40%). The above results show that in CO2The stability of the Pt-based catalyst and the yield of propylene can be obviously improved by introducing hydrogen into an ODP reaction system. At the same time, from CO2The introduction of hydrogen accelerates the RWGS process from the standpoint that conversion increases with increasing hydrogen addition.
As can be seen from FIG. 4, the catalyst has two weight loss peaks, the first one occurs before 200 ℃ and can be attributed to the dehydration process of the catalyst, and the second one occurs between 200 ℃ and 500 ℃ and can be attributed to the combustion process of carbon deposit. Comparing curves a and b in FIG. 4, CO2-H2The carbon deposit amount of the catalyst after the reaction of-PDH is obviously less than that of CO2Carbon deposit on the catalyst after ODP reaction, indicated in CO2The introduction of hydrogen into the ODP reaction system can obviously reduce carbon deposition and inhibit the occurrence of carbon deposition reaction. CO 22-H2The exothermic peak of burning of coke on the DSC curve of the catalyst after the PDH reaction was not evident (FIG. 5), which is caused by too little amount of coke.
From the stoichiometric relationship and reaction principle of propane dehydrogenation and RWGS, if the reaction rate of propane dehydrogenation is equal to that of RWGS and other side reactions such as propane thermal cracking and carbon deposit do not occur, H is2Must equal the rate of CO generation2That is to say the invention is in CO2And H2The dehydrogenation reaction of propane under the coexistence condition is substantially to utilize the added CO2Consumption ofHydrogen, CO, formed by dehydrogenation of propane2-H2PDH is carried out by reactive coupling of PDH and RWGS with addition of CO2And H2The RWGS reaction rate is improved, and carbon deposition on the surface of the catalyst is inhibited, so that the propane conversion rate and the stability of the catalyst are improved.
Example 2
500mg of 40-60 meshes of 1 wt.% Pt-1.2 wt.% SnO2-3wt.％CeO2/Al2O3The catalyst was packed in a quartz tube (length 40cm, inner diameter 6mm) of a mini fixed bed reactor, and H was fed into the reactor at a total gas flow rate of 50mL/min2And He, H2And the volume ratio of the He to the reaction gas is 1:9, the temperature is raised from room temperature to 500 ℃ at the temperature rise rate of 5 ℃/min, the He is switched after reduction is carried out for 1h, the temperature is continuously raised to 600 ℃, then the reaction gas and the argon gas are switched, the total flow of the gas is 50mL/min, the operation pressure is 0.1MPa, and sampling analysis is started after the gas is stable. Wherein the reaction gas is CO2And H2、C3H8Mixed gas with volume ratio of 1:1:1, C3H8The volume ratio to Ar was 8: 1.
As can be seen in FIG. 6, 1 wt.% Pt to 1.2 wt.% SnO2-3wt.％CeO2/Al2O3With the highest propane conversion, decreasing from the initial 54% (TOS 5min) to 49% (TOS 80min), propylene yield was maintained at 45% over 80min (fig. 7). Simultaneous analysis of CO in the reaction process2The conversion can be found (FIG. 8), CO during the whole reaction2The conversion of (c) stabilized at about 47% (TOS ═ 80min), CO2With propane to CO and H2The reforming reaction of (a) ultimately favors both propane and CO2The transformation of (3). As can be seen from FIG. 9, H is present throughout the reaction2The conversion of (A) is negative, indicating that the reaction does not consume H while producing propylene2And the synthesis gas is enriched.
Example 3
Respectively mixing 500mg of 40-60 meshes of 1 wt.% Pt-1.2 wt.% SnO2/Al2O3And 1 wt.% Pt-1.2 wt.% SnO2-3wt.％CeO2/Al2O3Catalyst loading into micronIn a quartz tube (length 40cm, inner diameter 6mm) of a model fixed bed reactor, H was fed into the reactor at a total gas flow rate of 50mL/min2And He, H2And the volume ratio of the He to the reaction gas is 1:9, the temperature is raised from room temperature to 500 ℃ at the temperature rise rate of 5 ℃/min, the He is switched after reduction is carried out for 1h, the temperature is continuously raised to 600 ℃, then the reaction gas and the argon gas are switched, the total flow of the gas is 50mL/min, the operation pressure is 0.1MPa, and sampling analysis is started after the gas is stable. Wherein the reaction gas is CO2And H2、C3H8Mixed gas with volume ratio of 1:1:1, C3H8The volume ratio to Ar was 8: 1.
As can be seen from FIGS. 10 and 11, at 9h of reaction, 1 wt.% Pt to 1.2 wt.% SnO2-3wt.％CeO2/Al2O3The propane conversion of (a) was reduced from 56% to 38%, and the propylene yield was reduced from 45% to 33%; and when the reaction is carried out for 6 hours, 1 wt.% Pt-1.2 wt.% SnO2/Al2O3The propane conversion had decreased from 45% to 19% and the propylene yield from 40% to 18%. Thus, 1 wt.% Pt to 1.2 wt.% SnO2-3wt.％CeO2/Al2O3Has higher catalytic activity and stability. As can be seen from FIG. 12, 1 wt.% Pt to 1.2 wt.% SnO were reacted for 9h2-3wt.％CeO2/Al2O3CO of2The conversion can be stabilized above 45%, and when the reaction is carried out for 6 hours, 1 wt.% Pt-1.2 wt.% SnO2/Al2O3CO of2The conversion is around 40%, which indicates 1 wt.% Pt-1.2 wt.% SnO2-3wt.％CeO2/Al2O3Relative to 1 wt.% Pt-1.2 wt.% SnO2/Al2O3The deactivation rate of the catalyst is reduced, and high catalytic activity can be maintained for a long time.
Example 4
500mg of 40-60 meshes of 1 wt.% Pt-1.2 wt.% SnO2-3wt.％CeO2/Al2O3The catalyst was packed in a quartz tube (length 40cm, inner diameter 6mm) of a mini fixed bed reactor, and H was fed into the reactor at a total gas flow rate of 50mL/min2And He, H2The volume ratio of He to He is 1:9, and the temperature is raised at 5 ℃/minThe speed is increased from room temperature to 500 ℃, He is switched after reduction for 1h, the temperature is continuously increased to 600 ℃, then reaction gas and argon are switched, the total flow of the gas is 50mL/min, and the operation pressure is 0.1 MPa. Wherein the reaction gas is CO2And H2、C3H8Mixed gas with volume ratio of 1:1:1, C3H8The volume ratio to Ar was 8: 1. After the reaction is carried out for 9 hours, the catalyst is regenerated for 1 hour at 500 ℃ in the air atmosphere, and then the catalytic performance test under the same reaction conditions is carried out, and the result is shown in FIGS. 13-15.
As can be seen from fig. 13, the propane conversion of the regenerated catalyst was reduced, which is related to the increase of Pt particles of the regenerated catalyst, but the selectivity was improved compared to the fresh catalyst, and as can be seen from fig. 14, the propylene yield of the regenerated catalyst can return to the initial value (44%) with the change of the reaction time, and the propylene yield decreases from 44% to 27% (16h) with the progress of the reaction. Regenerated CO2The conversion rate was slightly lower than that of the fresh catalyst, but it was also stabilized at 40% or more (FIG. 15). Overall the catalyst regeneration performance is good.

Claims (6)

1. A method for preparing propylene and synthesis gas simultaneously by carbon dioxide propane oxide hydrodehydrogenation is characterized in that: the method is characterized in that carbon dioxide gas and hydrogen are introduced simultaneously in the process of preparing propylene by direct dehydrogenation of propane.
2. The method for simultaneously producing propylene and synthesis gas by the hydrodehydrogenation of propane oxide with carbon dioxide as claimed in claim 1, wherein: the volume ratio of the introduced carbon dioxide gas, the introduced hydrogen and the introduced propane is 0.5-5.0: 0.5-3.0: 1.0.
3. The method for simultaneously producing propylene and synthesis gas by the hydrodehydrogenation of propane oxide with carbon dioxide as claimed in claim 2, wherein: the volume ratio of the introduced carbon dioxide gas, the introduced hydrogen gas and the introduced propane is 1-2: 1-1.5: 1.
4. The carbon dioxide and oxygen as claimed in any one of claims 1 to 3The method for simultaneously preparing propylene and synthesis gas by dehydrogenating propane in the presence of hydrogen is characterized by comprising the following steps: the catalyst used in the method is Pt-SnO2/Al2O3Or Pt-SnO2-CeO2/Al2O3。
5. The method for simultaneously producing propylene and synthesis gas by the hydrodehydrogenation of propane oxide with carbon dioxide as claimed in claim 4, wherein: in the catalyst, the weight of the catalyst is 100%, the load of Pt is 0.1-1.0%, and SnO2The loading amount of the CeO is 0.5 to 5.0 percent2The loading amount of the catalyst is 0.1-5.0%.
6. The method for simultaneously producing propylene and synthesis gas by the hydrodehydrogenation of propane oxide with carbon dioxide as claimed in any one of claims 1 to 3, wherein: the reaction temperature of the method is 500-650 ℃, and the operation pressure is 0.05-0.15 MPa.
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