CN114602499B - Anti-sintering PtCu-BO x /SiO 2 High-stability catalyst and preparation method and application thereof - Google Patents

Anti-sintering PtCu-BO x /SiO 2 High-stability catalyst and preparation method and application thereof Download PDF

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CN114602499B
CN114602499B CN202210234162.6A CN202210234162A CN114602499B CN 114602499 B CN114602499 B CN 114602499B CN 202210234162 A CN202210234162 A CN 202210234162A CN 114602499 B CN114602499 B CN 114602499B
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CN114602499A (en
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丘勇才
林家瑾
赵帅奇
陈光需
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South China University of Technology SCUT
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8926—Copper and noble metals
    • B01J35/40—
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Abstract

The invention discloses an anti-sintering PtCu-BO x /SiO 2 High-stability catalyst and its preparation method and application. The preparation method comprises the following steps: preparing a silicon dioxide carrier loaded with boron oxide by an isovolumetric impregnation method, and drying; roasting the dried material to obtain a carrier; mixing and grinding the carrier and copper acetylacetonate, and roasting the mixture after uniform grinding; reducing the roasted material in a reducing atmosphere to obtain the sintering-resistant PtCu-BO x /SiO 2 A high stability catalyst. The preparation method disclosed by the invention is simple in preparation process, low in cost, small in size of the obtained catalyst, uniform in morphology and high in dispersibility of the PtCu alloy formed on the carrier. The catalyst has a plurality of active sites, so that the catalyst has higher propane conversion rate and propylene selectivity at high temperature, and has better stability and sintering resistance due to the action of boron oxide serving as a third carrier, and can be effectively utilized in practical application.

Description

Anti-sintering PtCu-BO x /SiO 2 High-stability catalyst and preparation method and application thereof
Technical Field
The invention belongs to the technical field of thermocatalytic dehydrogenation and nanomaterials, and in particular relates to an anti-sintering PtCu-BO x /SiO 2 High-stability catalyst and its preparation method and application.
Background
Propylene is an important organic basic chemical raw material with the yield inferior to that of ethylene, is widely used for producing chemical products such as polypropylene, acrylonitrile, epoxypropane and the like, and is a basic raw material of three major synthetic materials (plastics, rubber and fibers). In recent years, with the continuous development of global economy, the demand for propylene downstream products has been increasing, so that the demand for propylene has also been increasing. Currently, the sources of propylene supply are mainly naphtha steam cracking and catalytic cracking processes, which are considered as the main routes for oil-to-propylene production. However, the conventional route technology for producing propylene from oil is difficult to meet the requirements of propylene production and life. Therefore, development of a novel propylene production technology with high efficiency and high selectivity is very important.
Propane Dehydrogenation (PDH) is one of the efficient industrial processes for producing propylene, and compared with the traditional naphtha propylene production route, the production process has the advantages of high propylene selectivity, simple product composition, easy separation and the like. It is becoming particularly important to develop efficient catalysts for converting propane into propylene, among which Pt-based catalysts are widely used in PDH reactions due to high reactivity, high propylene selectivity and low toxicity, relative to other catalysts such as metal oxides. However, pt particles or clusters are easy to sinter and grow up under high temperature conditions, and meanwhile, carbon deposition and inactivation are easy to occur, so that the stability is poor, and the application of the Pt particles or clusters in actual production is greatly limited. The design and preparation of the sintering-resistant Pt-based catalyst have important roles in the production of propylene in the actual industrial process.
In general, the Pt-based catalyst affects the catalytic activity and stability of the catalyst in terms of its electronic structure, geometric factors, interactions with the carrier, and the like, and the stability mainly includes stability in terms of sintering resistance and carbon deposit resistance. These properties are all related to the dispersion of Pt particles or clusters, size of the particles, the kind and amount of additives added, the nature of the support, etc. At present, a large amount of metal auxiliary agent and Pt form alloy particles or clusters so as to modulate the geometric characteristics and electronic structure of Pt and further modulate the catalytic activity and the anti-carbon performance. Wherein the common auxiliary agents of the Pt-based catalyst in the PDH reaction are Sn, cu, zn, ga and the like, and the research indicates that the PtCu alloy prepared is loaded on Al 2 O 3 The catalyst can effectively improve the activity and stability of propylene prepared by catalyzing propane [ Sun, G., zhao, ZJ., mu, R.et al, break the scaling relationship via thermally stable Pt/Cu single atom alloys for catalytic dehydrogenization. Nat Commun 9,4454 (2018).]However, the preparation method is complex, and the stability of the formed catalyst is still poor, and the catalyst is catalyzedIn the reaction process, ptCu alloy in an active center can be sintered and agglomerated, so that the activity is continuously reduced, the catalyst has poor general applicability and low catalyst utilization rate, and the cost is increased.
Thus, in view of these general problems, ptCu-SiO with higher activity 2 The third carrier boron oxide is introduced into the catalyst to form a plurality of metal-carrier interface interactions, so that the formed interface effect can effectively protect PtCu alloy nano particles or clusters serving as active centers, and meanwhile, the formed interface effect is neither too strong nor too weak due to the plurality of interactions, so that the sintering-resistant temperature of the bifunctional carrier catalyst is higher, and the PtCu alloy nano catalyst/double-active carrier combination has better activity and stability for preparing propylene by dehydrogenating propane. Meanwhile, as B element is introduced into the catalyst, the B element is BO in the system after roasting and reduction at high temperature x In the form of (a) BO formed x The PtCu alloy can be used as a protective layer to wrap the surface of PtCu alloy, so that agglomeration caused by sintering of PtCu in an active center in a high-temperature reaction process can be avoided to a certain extent, the activation capability of PtCu on a C-C bond can be reduced, the propylene selectivity is further improved, and the generation of carbon deposit is reduced.
Therefore, based on the above discussion, a material with high catalytic activity and high stability can be explored, and the material is expected to be widely used in practical production and application of propylene prepared by propane dehydrogenation.
Disclosure of Invention
The invention aims at overcoming various defects existing in the prior art and aims at providing the sintering-resistant PtCu-BO x /SiO 2 High-stability catalyst and its preparation method and application. The invention relates to an anti-sintering PtCu-BO x /SiO 2 The high-stability catalyst has the advantages of simple preparation process, low cost, good repeatability, mass production, high activity, high selectivity and good catalytic stability for preparing propylene by catalyzing propane dehydrogenation.
The invention is mainly realized by the following technical scheme.
The invention provides an anti-sintering PtCu-BO x /SiO 2 A method for preparing a high stability catalyst comprising the steps of:
(1) Preparing a silicon dioxide carrier loaded with boron oxide by using an isovolumetric impregnation method, and then drying;
(2) Roasting the material obtained by drying in the step (1) in air to obtain a corresponding carrier;
(3) Mixing the carrier in the step (2) with copper acetylacetonate, and roasting after uniformly grinding platinum acetylacetonate;
(4) Reducing the material obtained by roasting in the step (3) in a reducing atmosphere to obtain the sintering-resistant PtCu-BO x /SiO 2 A high stability catalyst.
Preferably, the mass ratio of boric acid to silicon dioxide used for preparing the silicon dioxide carrier loaded with boron oxide by the isovolumetric impregnation method in the step (1) is 1:100-5:100.
Preferably, the specific steps for preparing the silica carrier loaded with boron oxide by the isovolumetric impregnation method in the step (1) are as follows: boric acid is dissolved in water, and the concentration of the boric acid solution is 0.023mol/L to 0.124mol/L; then, boric acid solution was added dropwise to the fumed silica powder, the mass content of silica was 2g, and the mixture was subjected to an isovolumetric impregnation reaction.
Preferably, the concentration of the boric acid solution is 0.023mol/L to 0.094mol/L.
Preferably, in the step (1), the time of the isovolumetric impregnation is 10-30 min, and the temperature of the isovolumetric impregnation is 20-30 ℃.
Preferably, in the step (1), the time of the isovolumetric impregnation is 10-20 min, and the temperature of the isovolumetric impregnation is 20-25 ℃.
Preferably, in the step (1), the drying temperature is 60-90 ℃, and the drying time is 10-12 h.
Preferably, in step (1), the drying temperature is 60 ℃ to 80 ℃.
Preferably, in the step (2), the roasting temperature is 600-800 ℃.
Preferably, in the step (2), the roasting temperature is 600-700 ℃, and the roasting time is 1-2 h.
Preferably, in the step (3), the mass ratio of the carrier to the copper acetylacetonate is 1.86:1-29.76:1, the mass ratio of the carrier to the platinum acetylacetonate is 50:1-200:1, and the mass ratio of the copper acetylacetonate to the platinum acetylacetonate is 2.9:1-27:1.
Preferably, the grinding time in the step (3) is 15-25 min.
Preferably, in the step (3), the roasting temperature is 350-450 ℃, and the roasting time is 1-2 h.
Preferably, in the step (4), the reducing atmosphere is H 2 Ar atmosphere, H 2 The volume fraction was 5%.
Preferably, in the step (4), the temperature of the reduction is 550-650 ℃, and the time of the reduction is 0.5-4.0 h.
Preferably, in the step (4), the temperature of the reduction is 550-600 ℃, and the time of the reduction is 0.5-1.0 h.
The sintering-resistant PtCu-BO in the step (4) x /SiO 2 The carrier in the high-stability catalyst is composed of Cu 2 O,SiO 2 ,BO x Three-phase carrier, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
The invention provides the anti-sintering PtCu-BO prepared by the preparation method x /SiO 2 A high stability catalyst.
The invention also provides the sintering-resistant PtCu-BO x /SiO 2 The application of the high-stability catalyst in preparing industrial raw material propylene by directly dehydrogenating catalytic conversion propane at high temperature.
Preferably, the heating means in the application is direct heating.
Compared with the prior art, the invention has the following beneficial effects:
1. the preparation process is simple, the cost is relatively low, the size of the obtained catalyst is smaller (20 nm), the morphology is more uniform, the particle size of PtCu is smaller (1-2.5 nm), the dispersibility is higher, the repeatability is better, and the catalyst has higher thermocatalytic performance.
2. In PtCu-SiO with higher activity 2 Introduction of third Carrier BO into catalyst x The interface effect formed can effectively protect PtCu alloy nano particles or clusters serving as active centers, and the interface effect formed is neither too strong nor too weak due to the existence of the plurality of interactions, so that the sintering-resistant temperature of the dual-function carrier catalyst is higher, and the PtCu alloy nano catalyst/dual-activity carrier combination has better activity and stability for preparing propylene by dehydrogenating propane.
3. At a reaction temperature of 600 ℃, the partial pressure of propane is 0.19MPa, the gas volume ratio of propane to hydrogen is 1:1, N 2 To balance the gas, the total gas flow rate was 42mL per minute, and the space velocity was 4h -1 Under the condition of PtCu-BO x /SiO 2 The stability in the catalyst was optimal and the deactivation constant was minimal (-0.0056 h) -1 ) And PtCu-BO x /SiO 2 II has a starting point selectivity of 94% and the selectivity of the catalyst increases continuously with increasing reaction time. Further explaining that B element is introduced into the catalyst, and after roasting and reduction at high temperature, the B element is BO in the system x Form(s) of (a) form(s) a plurality of interfacial interactions on the one hand and BO(s) formed on the other hand x The PtCu alloy can be used as a protective layer to wrap the surface of PtCu alloy, so that agglomeration caused by sintering of PtCu in an active center in a high-temperature reaction process can be avoided, the activation capability of PtCu on C-C bond fracture can be reduced, the propylene selectivity is further improved, and the generation of carbon deposit is further reduced. The catalyst of the invention can be fully used in the practical application of propylene preparation by propane dehydrogenation.
Drawings
FIG. 1 is XRD patterns of the catalysts prepared in comparative example 1 and examples 1 to 3.
FIG. 2 shows PtCu-SiO obtained in comparative example 1 2 SEM image of the catalyst;
FIG. 3 shows PtCu-BO prepared in example 1 x /SiO 2 -SEM images of the catalyst.
FIG. 4 shows PtCu-BO prepared in example 2 x /SiO 2 -SEM pictures of the catalyst.
FIG. 5 shows PtCu-BO prepared in example 3 x /SiO 2 SEM pictures of the III catalyst.
FIG. 6 shows PtCu-SiO obtained in comparative example 1 2 TEM image of the catalyst.
FIG. 7 shows PtCu-SiO obtained in comparative example 1 2 HAADF-STEM diagram of catalyst.
FIG. 8 shows PtCu-BO prepared in example 2 x /SiO 2 -II TEM image of catalyst.
FIG. 9 shows PtCu-BO prepared in example 2 x /SiO 2 HAADF-STEM diagram of the catalyst.
FIG. 10 shows PtCu-SiO obtained in comparative example 1 2 Catalyst PtCu-SiO after propane dehydrogenation test 2 -a used TEM image.
FIG. 11 shows PtCu-SiO obtained in comparative example 1 2 Catalyst PtCu-SiO after propane dehydrogenation test 2 -HAADF-STEM map of used.
FIG. 12 shows PtCu-BO prepared in example 2 x /SiO 2 Catalyst PtCu-BO after propane dehydrogenation test of-II catalyst x /SiO 2 -TEM image of II-used.
FIG. 13 shows PtCu-BO prepared in example 2 x /SiO 2 Catalyst PtCu-BO after propane dehydrogenation test of-II catalyst x /SiO 2 II-used HAADF-STEM map.
Fig. 14 is an XRD pattern of the catalysts prepared in comparative example 1 and example 2 and the catalysts after propane dehydrogenation test.
FIG. 15 is a graph showing the conversion of propane by catalytic direct dehydrogenation to propylene for the catalysts prepared in comparative example 1 and examples 1-3, which were subjected to propane dehydrogenation at a reaction temperature of 600 ℃.
FIG. 16 is a graph showing the selectivity of the catalysts prepared in comparative example 1 and examples 1 to 3 for the catalytic direct dehydrogenation of propane to propylene at a reaction temperature of 600℃for 10 hours.
FIG. 17 is a graph showing the conversion of propane to propylene by catalytic direct dehydrogenation at 600℃for 10 hours using the catalysts prepared in example 2 and examples 4 to 5.
FIG. 18 is a graph showing the selectivity of the catalysts prepared in examples 2 and 4 to 5 for the catalytic direct dehydrogenation of propane to propylene at a reaction temperature of 600℃for 10 hours.
Detailed Description
The preparation method and application of the present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in understanding the invention without limiting it in any way. It should be noted that modifications and optimizations may be made by those of ordinary skill in the art without departing from the spirit and subject matter of the present invention. These are all within the specific scope of the present invention.
Comparative example 1
PtCu-SiO 2 Preparation of the catalyst:
(1) 1000mg of gas phase SiO was weighed 2 Grinding 268.3mg of copper acetylacetonate and 20mg of platinum acetylacetonate powder together for 25min, and then placing the powder into a muffle furnace for roasting at 450 ℃ for 2h;
(2) The material roasted in the step (1) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-SiO 2 。
Example 1
PtCu-BO x /SiO 2 -preparation of the catalyst:
(1) Weighing 20mg of boric acid, dissolving in 14mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -I；
(3) Weighing 1000mg of carrier SiO 2 -BO x Powder I, 268.3mg of copper acetylacetonate and 20mg of platinum acetylacetonate powder are ground together for 25min and then put into a muffle furnace for roasting at 450 ℃ for 2h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 -I, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
Example 2
PtCu-BO x /SiO 2 -II preparation of the catalyst:
(1) Weighing 50mg of boric acid, dissolving in 13.5mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -II；
(3) 1000mg of carrier SiO was weighed 2 -BO x Powder II, 268.3mg of copper acetylacetonate and 20mg of platinum acetylacetonate powder are ground together for 25min and then put into a muffle furnace for roasting at 450 ℃ for 2h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 -II, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
Example 3
PtCu-BO x /SiO 2 Preparation of the catalyst:
(1) Weighing 100mg of boric acid, dissolving in 13mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -III；
(3) 1000mg of carrier SiO was weighed 2 -BO x Powder III, 268.3mg of copper acetylacetonate and 20mg of platinum acetylacetonate powder are ground together for 25min and then put into a muffle furnace for roasting at 450 ℃ for 2h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 -III, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
As can be seen from FIG. 1, XRD (X-ray diffraction) patterns of the catalysts prepared in comparative example 1 and examples 1 to 3 are shown in FIG. 1, the catalysts are mainly composed of SiO 2 And the diffraction peak of the simple substance Cu is mainly, and no obvious diffraction peak of Pt is seen, which indicates that Pt in the catalyst of the system has good dispersibility. The XRD analysis of the catalyst after the boron oxide is introduced can be obtained, the diffraction peak of the catalyst after the boron oxide is introduced is not changed obviously, which indicates that the introduction of the boron oxide does not change the lattice system of the catalyst, and no obvious peak of Pt is seen, which indicates that Pt is not agglomerated and has higher dispersibility. SEM (scanning electron microscope) images of the catalysts prepared in comparative example 1 and examples 1 to 3 are shown in fig. 2 to 5, and it can be seen that the morphology of the catalysts prepared in comparative example 1 and examples 1 to 3 is relatively uniform, mainly particles with the size of about 20nm, and the morphology of the catalysts is not changed due to the introduction of boron oxides with different contents, which indicates that the morphology of the catalysts has relatively high repeatability.
The TEM (transmission electron microscope) and HAADF-STEM spectra of the catalysts prepared in comparative example 1 and example 2 are shown in FIGS. 6 to 9, and it can be seen from FIGS. 6 to 7 that PtCu-SiO 2 PtCu alloy nano particles or clusters formed in the catalyst have smaller size (1-2.5 nm) and higher particle dispersibility. As can be seen from fig. 8-9, the boron oxide is introduced into the catalyst, and the size and dispersibility of PtCu alloy nanoparticles or clusters are not significantly changed by using the boron oxide as the third carrier, which indicates that the distribution of active sites of the catalyst is not changed in the system by using the boron oxide as the third carrier, so that the catalyst still has higher catalytic activity. Comparative example 1 and examplesThe TEM and HAADF-STEM spectra of the catalyst prepared in example 2 after the catalyst was subjected to the propane dehydrogenation test under the same conditions are shown in FIGS. 10 to 13, and it can be seen from a comparison of FIGS. 10 to 11 and FIGS. 6 to 7 that PtCu-SiO 2 After the catalyst is subjected to propane dehydrogenation test at 600 ℃ for 10 hours, ptCu alloy nano particles or clusters are obviously agglomerated, the size is obviously enlarged, the active sites of the catalyst are reduced, and the activity of the catalyst is reduced. As can be seen by comparing FIGS. 12-13 with FIGS. 8-9, ptCu-BO x /SiO 2 After the propane dehydrogenation test of the II catalyst under the same 600 ℃ and 10 hours reaction condition, ptCu alloy nano particles or clusters are not obviously agglomerated and still have higher dispersivity, which indicates that the introduction of boron oxide as a third carrier can effectively prevent the PtCu alloy nano particles or clusters from agglomerating in the process of catalyzing propane dehydrogenation while the size of the PtCu alloy nano particles or clusters in the original catalyst is not influenced, so that the catalyst still has more active sites and maintains higher catalytic activity and catalytic selectivity for preparing propylene by propane dehydrogenation.
The XRD of the catalysts prepared in comparative example 1 and example 2 and the catalysts after propane dehydrogenation test are shown in FIG. 14, and it can be seen from FIG. 14 that PtCu-SiO after propane dehydrogenation test 2 Although the catalyst sees PtCu nanoparticles or clusters partially agglomerated according to TEM, no significant diffraction peak of Pt is seen in XRD of FIG. 14, and PtCu-BO is also seen x /SiO 2 The II catalyst also did not see a significant diffraction peak for Pt, indicating that Pt still has a higher dispersibility in both catalysts.
Propylene was prepared by catalytic dehydrogenation of propane using the catalysts prepared in comparative example 1 and examples 1-3, under the following reaction conditions: the partial pressure of propane under the test condition of 600 ℃ is 0.19MPa, the gas volume ratio of propane to hydrogen is 1:1, N 2 To balance the gas, the total gas flow rate was 42mL per minute, and the space velocity was 4h -1 The results of the test conversion under this gas condition are shown in fig. 15. As can be seen from FIG. 15, the catalysts of examples 1 to 3 were obtained by introducing boron oxide as the third carrierAlthough the initial conversion of propane to propylene is lower than PtCu-SiO 2 Catalysts (initial conversion 57%) but the catalysts of examples 1-3 have better stability and smaller deactivation constants, wherein PtCu-BO is prepared in the method of example 2 x /SiO 2 The stability in the catalyst was optimal and the deactivation constant was minimal (-0.0056 h) -1 ) The boron oxide is introduced into the catalyst as a third carrier, and the PtCu alloy nano particles or clusters can be effectively protected due to strong interaction among the carriers, so that aggregation of the PtCu alloy nano particles or clusters caused by long-time high temperature in the catalytic reaction process is prevented, and the catalytic activity is maintained in a higher state for a longer time. At the same time, BO is formed x The PtCu nano alloy particles or clusters are wrapped on the periphery of the PtCu nano alloy particles or clusters to play a role of a protective layer, so that the PtCu nano alloy particles or clusters have higher catalytic activity for converting propane into propylene and better stability. The results of the selectivity for the conversion of propane to propylene under these gas conditions are shown in FIG. 16, and it can be seen from FIG. 16 that the selectivity of the catalyst systems of examples 1-3 are all higher than 90%, wherein PtCu-BO x /SiO 2 The catalyst has 94% starting point selectivity, and the selectivity of the catalyst is continuously improved along with the extension of the reaction time, so that the boron oxide serving as a third carrier is beneficial to reducing the activity of PtCu alloy particles or clusters on C-C bond breakage while improving the catalytic stability, and further cracking of propylene is avoided, the catalytic selectivity is improved, and the catalyst provided by the invention can be fully and effectively utilized in practical application.
Example 4
PtCu-BO x /SiO 2 Preparation of the IV catalyst:
(1) Weighing 50mg of boric acid, dissolving in 13mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -II；
(3) 1000mg of carrier SiO was weighed 2 -BO x -II powder, 67.1mg copper acetylacetonate and 20mg platinum acetylacetonate powder together ground for 25min and then put into a muffle furnace for roasting at 450 ℃ for 2h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 -IV, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
Example 5
PtCu-BO x /SiO 2 -V preparation of the catalyst:
(1) Weighing 100mg of boric acid, dissolving in 13mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -II；
(3) 1000mg of carrier SiO was weighed 2 -BO x -II powder, 536.6mg copper acetylacetonate and 20mg platinum acetylacetonate powder together ground for 25min and then placed in a muffle furnace for 2h at 450 ℃;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 V, where BO x Wherein x represents oxygen content, 1<x<1.5。
Propylene was prepared by catalytic dehydrogenation of propane using the catalysts prepared in example 2, example 4 and example 5, the reaction conditions being: the partial pressure of propane under the test condition of 600 ℃ is 0.19MPa, the gas volume ratio of propane to hydrogen is 1:1, N 2 To balance the gas, the total gas flow rate was 42mL per minute, and the space velocity was 4h -1 The results of the test conversion under this gas condition are shown in fig. 17. It can be seen from FIG. 17 that the catalyst prepared in example 4 had an initial propane conversion of 57%, albeit higher, at different Pt and Cu levelsThe catalyst prepared by the method of example 2, but the catalyst prepared by the method of example 4 had a deactivation constant of 0.043h -1 The catalyst prepared in example 5 had an initial propane conversion of 41% and a deactivation constant of 0.041h -1 All are far greater than the deactivation constant of the catalyst prepared in example 2, indicating that the catalyst has optimal catalytic stability and minimal deactivation constant at an atomic ratio of Pt to Cu of 1:20. Meanwhile, the selectivity result of propane conversion to propylene under the gas condition is shown in fig. 18, and it can be seen from fig. 18 that the catalyst prepared in example 2 has better catalytic selectivity than the catalyst prepared in the methods of examples 4-5, which indicates that the catalyst has optimal propane conversion, propylene selectivity and catalytic stability in the presence of boron oxide when the atomic ratio of Pt to Cu is 1:20.
Example 6
PtCu-BO x /SiO 2 Preparation of the-VI catalyst:
(1) Weighing 50mg of boric acid, dissolving in 13mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -II；
(3) 1000mg of carrier SiO was weighed 2 -BO x -II powder, 67.1mg copper acetylacetonate and 10mg platinum acetylacetonate powder together ground for 25min and then put into a muffle furnace for roasting at 450 ℃ for 2h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 -VI wherein BO x Wherein x represents oxygen content, 1<x<1.5。
Example 7
PtCu-BO x /SiO 2 Preparation of the VII catalyst:
(1) Weighing 50mg of boric acid, dissolving in 13mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 25 ℃ for 20min, and drying at 80 ℃ for 12h in a forced air drying oven;
(2) Roasting the dried material in the step (1) in a muffle furnace for 2 hours at the temperature of 700 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -II；
(3) 1000mg of carrier SiO was weighed 2 -BO x -II powder, 33.6mg copper acetylacetonate and 5mg platinum acetylacetonate powder together ground for 25min and then put into a muffle furnace for roasting at 450 ℃ for 2h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing for 1h at 600 ℃ to obtain a catalyst PtCu-BO x /SiO 2 -VII, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
Through experiments, the partial pressure of propane under the test condition of 600 ℃ is 0.19MPa, the gas volume ratio of propane to hydrogen is 1:1, and N is obtained 2 To balance the gas, the total gas flow rate was 42mL per minute, and the space velocity was 4h -1 The catalyst prepared in example 6 had an initial propane conversion of 49% and a deactivation constant of 0.0079h -1 The catalyst prepared in example 7 had an initial propane conversion of 42% and a deactivation constant of 0.0115h -1 Comparison of the catalysts prepared in example 2 and examples 6-7 shows that the catalyst has the smallest deactivation constant and the optimal catalytic stability when the Pt content in the catalyst is about 1%.
Example 8
PtCu-BO x /SiO 2 Preparation of the-VIII catalyst:
(1) Weighing 50mg of boric acid, dissolving in 13mL of deionized water, dropwise adding into 2000mg of fumed silica to perform an equal volume impregnation reaction, performing ultrasonic impregnation at 20 ℃ for 10min, and drying at 60 ℃ for 10h in a forced air drying oven;
(2) Roasting the material dried in the step (1) in a muffle furnace for 1h at the temperature of 600 ℃ in air, and naturally cooling to obtain a carrier SiO 2 -BO x -VIII；
(3) 1000mg of carrier SiO was weighed 2 -BO x -VIII powder, 268.3mg copper acetylacetonate and 20mg platinum acetylacetonate powder were ground together for 20min and then placed in a muffle furnace for calcination at 350 ℃ for 1h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing at 550 ℃ for 0.5h to obtain the catalyst PtCu-BO x /SiO 2 -VIII, where BO x Wherein x represents oxygen content, 1<x<1.5。
Example 9
PtCu-BO x /SiO 2 Preparation of the IX catalyst:
(1) 50mg of boric acid is weighed and dissolved into 13mL of deionized water, then the solution is dropwise added into 2000mg of fumed silica to carry out an equal volume impregnation reaction, after ultrasonic impregnation is carried out for 15min at 22.5 ℃, the solution is dried at 70 ℃ for 11h in a blast drying box;
(2) Roasting the dried material in the step (1) in a muffle furnace for 1.5h at 650 ℃ to obtain a carrier SiO after natural cooling 2 -BO x -IX；
(3) 1000mg of carrier SiO was weighed 2 -BO x -IX powder, 268.3mg copper acetylacetonate and 20mg platinum acetylacetonate powder were milled together for 22.5min and then placed in a muffle furnace for calcination at 400 ℃ for 1.5h;
(4) The material roasted in the step (3) is treated by H 2 Ar atmosphere (5 vol.% H) 2 ) Reducing at 575 ℃ for 0.75h to obtain the catalyst PtCu-BO x /SiO 2 -IX, wherein BO x Wherein x represents oxygen content, 1<x<1.5。
Through experiments, the propane is obtained at 600 ℃, the partial pressure is 0.19MPa, the gas volume ratio of the propane to the hydrogen is 1:1, and N 2 To balance the gas, the total gas flow rate was 42mL per minute, and the space velocity was 4h -1 The catalyst prepared in example 8 had an initial propane conversion of 33% and a deactivation constant of 0.042h -1 The catalyst prepared in example 9 had an initial propane conversion of 35% and a deactivation constant of 0.026h -1 By comparison with the catalyst prepared by the method of example 2, a catalyst is shownThe preparation conditions of the catalyst have a certain influence on the catalytic performance.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that modifications and optimizations may be made by those skilled in the art within the scope of the claims without affecting the essential content of the invention.

Claims (8)

1. Anti-sintering PtCu-BO x /SiO 2 The preparation method of the high-stability catalyst is characterized by comprising the following steps of:
(1) Preparing a silicon dioxide carrier loaded with boron oxide by using an isovolumetric impregnation method, and then drying; the mass ratio of boric acid to silicon dioxide used for preparing the silicon dioxide carrier loaded with boron oxide by the isovolumetric impregnation method is 1:100-5:100; the method for preparing the silicon dioxide carrier loaded with the boron oxide by the isovolumetric impregnation method comprises the following specific steps of: boric acid is dissolved in water, and the concentration of the boric acid solution is 0.023mol/L to 0.124mol/L; then adding boric acid solution into the fumed silica powder drop by drop, mixing and then carrying out an isovolumetric impregnation reaction;
(2) Roasting the material obtained by drying in the step (1) in air to obtain a carrier;
(3) Mixing the carrier in the step (2) with copper acetylacetonate, and roasting after uniformly grinding platinum acetylacetonate; the roasting temperature is 350-450 ℃;
(4) Reducing the material obtained by roasting in the step (3) in a reducing atmosphere to obtain the sintering-resistant PtCu-BO x /SiO 2 A high stability catalyst.
2. The sintering-resistant PtCu-BO of claim 1 x /SiO 2 The preparation method of the high-stability catalyst is characterized in that in the step (1), the time of the equal volume impregnation is 10-30 min, and the temperature of the equal volume impregnation is 20-30 ℃.
3. The sintering-resistant PtCu-BO of claim 1 x /SiO 2 The preparation method of the high-stability catalyst is characterized in that in the step (1), the drying temperature is 60-90 ℃ and the drying time is 10-12 h.
4. The sintering-resistant PtCu-BO of claim 1 x /SiO 2 The preparation method of the high-stability catalyst is characterized in that in the step (2), the roasting temperature is 600-800 ℃, and the roasting time is 1-2 h.
5. The sintering-resistant PtCu-BO of claim 1 x /SiO 2 The preparation method of the high-stability catalyst is characterized in that the grinding time in the step (3) is 15-25 min; and (3) roasting for 1-2 hours.
6. The sintering-resistant PtCu-BO of claim 1 x /SiO 2 A process for producing a highly stable catalyst, characterized in that in the step (4), the reducing atmosphere is H 2 and/Ar atmosphere, wherein the reduction temperature is 550-650 ℃, and the reduction time is 0.5-4.0 h.
7. The anti-sintering PtCu-BO prepared by the preparation method of any one of claims 1-6 x /SiO 2 A high stability catalyst characterized in that x Wherein x represents oxygen content, 1<x<1.5。
8. The anti-sintering PtCu-BO of claim 7 x /SiO 2 The application of the high-stability catalyst in preparing propylene by catalyzing propane dehydrogenation.
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