Catalyst for preparing ethylene and propylene by catalyzing bioethanol, and process and application thereof
阅读说明：本技术 一种催化生物乙醇制备乙烯和丙烯的催化剂及工艺与应用 (Catalyst for preparing ethylene and propylene by catalyzing bioethanol, and process and application thereof ) 是由 夏薇 王钧国 钱晨 黄娅新 马超 范瑜 候梦达 陈坤 黄飚 于 2021-01-29 设计创作，主要内容包括：本发明涉及生物乙醇催化转化制备低碳烯烃的应用领域,具体涉及一种催化生物乙醇制备乙烯和丙烯的催化剂及工艺与应用。为了解决目前乙醇制备烯烃的研究中均采用HZSM-5分子筛和改性分子筛催化剂,乙烯、丙烯的收率差且催化稳定性差(催化剂寿命小于8h)的问题,本发明提出一种催化生物乙醇制备乙烯和丙烯的催化剂,所述催化剂为ZrO-2/Cs-2O,所述催化剂中的含铯量为0.5mol％-10mol％,既能提高乙烯、丙烯的收率,又能保证催化剂的稳定性。(The invention relates to the application field of preparing low-carbon olefin by catalytic conversion of bioethanol, in particular to a catalyst for preparing ethylene and propylene by catalyzing bioethanol, a process and application thereof. In order to solve the problems that HZSM-5 molecular sieve and modified molecular sieve catalysts are adopted in the current research of preparing olefin from ethanol, and the yield of ethylene and propylene is poor and the catalytic stability is poor (the service life of the catalyst is less than 8 hours), the invention provides a catalyst for preparing ethylene and propylene from bioethanol, wherein the catalyst is ZrO 2 /Cs 2 O, the cesium content in the catalyst is 0.5 mol-10 mol%, can improve the yield of ethylene and propylene, and can ensure the stability of the catalyst.)
1. The catalyst for preparing ethylene and propylene by catalyzing bioethanol is characterized in thatThe catalyst being ZrO2/Cs2O。
2. The catalyst according to claim 1, wherein the cesium content in the catalyst is between 0.5% and 10%, preferably between 1% and 5%, more preferably 3%.
3. The method for preparing a catalyst according to any one of claims 1 to 2, comprising:
(1) dissolving a zirconium source and a cesium source in deionized water to obtain a mixed aqueous solution;
(2) adding a precipitant into the mixed aqueous solution under stirring;
(3) after the precipitant is added, the solution is continuously stirred and then is kept standing for precipitation;
(4) standing for precipitation, sequentially performing suction filtration, drying and roasting to obtain ZrO2/Cs2O。
4. The method of claim 3, wherein the molar ratio of the zirconium source, cesium source, and precipitating agent is 100: 1-10: 480-800.
5. The method of claim 3, wherein the zirconium source is ZrO (NO)3)2·2H2O and/or ZrOCl2·8H2O; the cesium source is cesium nitrate (CsNO)3) (ii) a The precipitant is one or more of ammonia water, sodium carbonate or sodium bicarbonate water solution.
6. The method for preparing the catalyst according to claim 3, wherein the precipitant is added dropwise to the mixed aqueous solution under vigorous stirring.
7. A process for the preparation of the catalyst according to claim 3, wherein after the addition of the precipitant, the stirring is continued for 0.5 to 1 hour, preferably 1 hour; then standing and precipitating for 12-36h, preferably 24 h.
8. A process for the preparation of the catalyst according to claim 3, characterized in that drying is carried out at 90 ℃ to 150 ℃ for 12h, preferably at 120 ℃ for 24 h.
9. The method of claim 3, wherein the dried sample is transferred to a muffle furnace and calcined at 500 ℃ to 700 ℃ for 5 to 8 hours, preferably at 540 ℃ to 640 ℃ for 5 to 6 hours, and more preferably at 540 ℃ for 6 hours.
10. The catalyst according to any one of claims 1-2 and/or the method of preparation according to claims 3-9 and the use of the catalyst prepared thereof for the preparation of ethylene and propylene.
Technical Field
The invention relates to the application field of preparing low-carbon olefin by catalytic conversion of bioethanol, in particular to a catalyst for preparing ethylene and propylene by catalyzing bioethanol, a process and application thereof.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
The low-carbon olefin (ethylene and propylene) is always the most important basic raw material in organic chemical industry and petrochemical industry, and the production level of the low-carbon olefin is an important index for measuring the development level of the national chemical industry. At present, ethylene and propylene mainly come from petroleum steam cracking and catalytic cracking processes, and in addition, other fossil resources (such as coal, natural gas and the like) can be used as raw materials to synthesize low-carbon olefins, but because fossil resources are increasingly deficient, a new technical approach must be found to increase the yield of ethylene and propylene on a large scale, and the contradiction between supply and demand of ethylene and propylene markets is relieved.
With the rapid progress of biological fermentation and biochemical technology, the technology for producing ethanol from biomass (especially lignocellulose and the like) has made an important breakthrough. Therefore, the production of petrochemical basic raw materials such as ethylene and propylene by using bioethanol becomes an important way for preparing low-carbon olefins in a non-fossil route, and the way not only expands the sources of ethylene and propylene, but also gradually weakens the excessive dependence on petroleum resources and can form a bio-chemical industry chain, so that the preparation of ethylene and propylene by using bioethanol draws wide attention of researchers and enterprises.
Transition metal oxides have an important position in industrial catalysis, in particular zirconium dioxide, which is the only metal oxide having acid, alkaline, oxidizing and reducing properties; the zirconium dioxide is a good carrier, can interact with active components, and has good catalytic effect. The acid and base centers on zirconium dioxide are weak, but they have a strong C-H bond cleavage activity, compared with SiO2The activity of MgO and the acid-base center are high, and the acid-base center has a synergistic catalytic effect and has good activity and selectivity for certain reactions. Therefore, the catalyst is widely applied to the aspects of alcohol dehydration, alkane isomerization and disproportionation, aromatization, methane oxidation, hydrocracking, polymerization, dehydrogenation, electrocatalysis and the like.
Most researchers have carried out ethanol-to-olefin conversion using H-ZSM-5 catalyst and ZSM-5 catalyst modified with metal or phosphorus, and it has been reported that alkali metal modified HZSM-5 molecular sieve catalyst has high performance in producing propylene from ethanol, Sr-HZSM-5 (SiO-HZSM-5) is synthesized under conditions of 500 ℃ and W/F ═ 0.03g · min/mL2/Al2O3184, Sr/Al 0.1, mole ratio) propylene yield on catalyst was about 32%; at 550 ℃, 0.1MPa, WHSV of 0.63h-1Under the condition of (Si/Al) on La modified HZSM-5 catalyst2＝280， La/Al22.2) propylene yield of about 31%; under the conditions of 823K, 0.1MPa, total flow rate of raw materials of 30mL/min and ethanol partial pressure of 50KPa, the P modified HZSM-5 catalyst (P/Al is 0.5, SiO2/Al2O380 mol ratio) was 32%, and in addition, in a Zr-modified HZSM-5 catalyst (SiO)2/Al2O380, molar ratio) the yield of propylene from ethanol was about 32%; converting ethylene to propylene using a SAPO-34 catalyst; converting ethylene to propylene and butene; converting ethanol into propylene by using HZSM-5/SAPO-34; thermodynamic evaluation of the reaction of ethanol to propylene. In summary, the catalysts used for preparing olefin from ethanol at present are mainly traditional solid acidsThe catalyst has the defects of unsatisfactory yield, poor stability of catalyst activity, easy loss of active components of the catalyst and the like in the conversion of ethanol to olefin.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a catalyst for preparing ethylene and propylene by catalyzing bioethanol, and a process and application thereof, which can ensure the conversion yield of bioethanol to ethylene and propylene and maintain good stability for a long time.
Specifically, the invention is realized by the following technical scheme:
in a first aspect, the invention provides a catalyst for catalyzing bioethanol to prepare ethylene and propylene, wherein the catalyst is ZrO2/Cs2O。
In a second aspect, the present invention provides a method for preparing a catalyst for catalyzing bioethanol to prepare ethylene and propylene, the method comprising:
(1) dissolving a zirconium source and a cesium source in deionized water to obtain a mixed aqueous solution;
(2) adding a precipitant into the mixed aqueous solution under stirring;
(3) after the precipitant is added, the solution is continuously stirred and then is kept standing for precipitation;
(4) standing for precipitation, sequentially performing suction filtration, drying and roasting to obtain ZrO2/Cs2O。
In a third aspect, the invention provides the catalyst for catalyzing bioethanol to prepare ethylene and propylene, a preparation method thereof, and application of the catalyst prepared by the preparation method in preparation of ethylene and propylene.
One or more embodiments of the present invention have the following advantageous effects:
1) the catalyst provided by the invention greatly improves the yield of ethylene and propylene, and has good activity and stability, and active components of the catalyst are not easy to lose.
2) At present, HZSM-5 molecular sieve and modified molecular sieve catalysts are adopted in the research of preparing olefin from ethanol, the ethylene yield is about 40%, the propylene yield is generally kept below 32%, and the catalytic stability is poor (the service life of the catalyst is less than 8 hours). The Cs-modified zirconium-based composite metal oxide synthesized by the method shows good selectivity and stability in the reaction from catalytic conversion of ethanol to ethylene and propylene, the yield of propylene is about 33.4%, the yield of ethylene is about 46.9%, and the yields of ethylene and propylene are greatly improved; and the stability of the catalyst is good within 100h, the ethylene yield is still kept about 40% within 100h, and the propylene yield is about 30%.
3) The preparation method is simple, and the Cs-doped zirconium-based composite metal oxide (ZrO) with both acid and alkali is synthesized by adopting a coprecipitation method2/Cs2O), it was found through studies that this zirconium-based composite metal oxide exhibits excellent selectivity and stability in the reaction of catalytically converting ethanol to ethylene and propylene.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 shows ZrO with different Cs contents2-Cs2XRD spectrum of O composite metal oxide;
FIG. 2 shows ZrO at various Cs contents2-Cs2NH of O-complex metal oxide3-a TPD spectrum;
FIG. 3 is a graph of the distribution of Cs-doped zirconium-based composite metal reaction products over time.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred embodiments and materials described herein are intended to be exemplary only.
In the prior art, HZSM-5 molecular sieve and modified molecular sieve catalysts are adopted in the research of preparing olefin from ethanol, the ethylene yield is about 40%, the propylene yield is generally kept below 32%, and the catalytic stability is poor (the service life of the catalyst is less than 8 hours).
In order to solve the problems, the invention provides a catalyst for catalyzing bioethanol to prepare ethylene and propylene, a process and application thereof, and specifically the invention is realized by the following technical scheme:
in a first aspect, the invention provides a catalyst for catalyzing bioethanol to prepare ethylene and propylene, wherein the catalyst is ZrO2/Cs2O。
In some embodiments, the cesium content of the catalyst is between 0.5% and 10%, preferably between 1% and 5%, and more preferably 3%, said percentages being expressed as molar percentages.
In a second aspect, the present invention provides a method for preparing a catalyst for catalyzing bioethanol to prepare ethylene and propylene, the method comprising:
(1) dissolving a zirconium source and a cesium source in deionized water to obtain a mixed aqueous solution;
(2) adding a precipitant into the mixed aqueous solution under stirring;
(3) after the precipitant is added, the solution is continuously stirred and then is kept standing for precipitation;
(4) standing for precipitation, sequentially performing suction filtration, drying and roasting to obtain ZrO2/Cs2O。
In some embodiments, the molar ratio of the zirconium source, cesium source, precipitating agent is 100: 1-10: 480-800.
In some embodiments, the molar ratio of the zirconium source, cesium source, and aqueous ammonia is 100: 1-10: 480-800.
In some embodiments, the zirconium source is ZrO (NO)3)2·2H2O and/or ZrOCl2·8H2O; the cesium source is cesium nitrate (CsNO)3) (ii) a The precipitant is one or more of ammonia water, sodium carbonate or sodium bicarbonate water solution.
In some embodiments, the mass fraction of the aqueous ammonia is 10% to 25%.
In some embodiments, the precipitant is added dropwise to the mixed aqueous solution under vigorous stirring.
In some embodiments, after the addition of the precipitant is complete, stirring is continued for 0.5 to 1 hour, preferably 1 hour; then standing and precipitating for 12-36h, preferably 24 h.
In some embodiments, drying is carried out at 90 ℃ to 150 ℃ for 12h, preferably at 120 ℃ for 24 h.
In some embodiments, the dried sample is transferred to a muffle furnace and calcined at 500 ℃ to 700 ℃ for 5 to 8 hours, preferably at 540 ℃ to 640 ℃ for 5 to 6 hours, and more preferably at 540 ℃ for 6 hours.
In some embodiments, an amount of ZrO (NO)3)2·2H2O and cesium nitrate (CsNO)3) Dissolving in deionized water, measuring appropriate amount of ammonia water, sodium carbonate or sodium bicarbonate water solution as precipitant (the precipitant capable of precipitating Zr and Cs completely is 1.2-2 times of theoretical dosage), and adding into beaker as precipitant. The precipitant was added dropwise thereto under vigorous stirring (the dropping speed was maintained at 1-2 drops/sec). After the dropwise addition, stirring is continued for 0.5h, and then standing and precipitating are carried out for 24 h. Pumping, drying at 120 deg.C for 24 hr, transferring the dried sample into a muffle furnace, and calcining at 540 deg.C (adjusted according to the experiment) for 6 hr to obtain ZrO2/Cs2And (3) an O catalyst.
In some embodiments, an amount of ZrO (NO)3)2·2H2O and cesium nitrate (CsNO)3) Dissolving in deionized water, precipitating with ammonia water, sodium carbonate and sodium bicarbonate, respectively, and ZrO (NO)3)2·2H2O and ZrOCl2·8H2Preparing the Cs-doped zirconium-based composite metal catalyst by taking O as a zirconium source, and adjusting the roasting temperature according to the experimental design.
In a third aspect, the invention provides the catalyst for catalyzing bioethanol to prepare ethylene and propylene, a preparation method thereof, and application of the catalyst prepared by the preparation method in preparation of ethylene and propylene.
Example 1
10g of ZrO (NO)3)2·2H2O and 0.07g of cesium nitrate (CsNO)3) Dissolving the mixture in 500ml of deionized water to obtain a mixed aqueous solution, measuring 17ml of 25% ammonia water as a precipitator, and dropwise adding the precipitator into the mixed aqueous solution under vigorous stirring (the dropwise adding speed is kept at 1-2 drops/second). After the dropwise addition, stirring is continued for 0.5h, and then standing and precipitating are carried out for 24 h. Pumping and filtering, putting into a drying oven, drying at 120 ℃ for 24h, transferring the dried sample into a muffle furnace, and roasting at 540 ℃ for 6h to obtain ZrO2/Cs2And (3) an O catalyst.
Example 2
10g of ZrO (NO)3)2·8H2O and 0.07g of cesium nitrate (CsNO)3) Dissolving the mixture in 500ml of deionized water to obtain a mixed aqueous solution, measuring 17ml of 25% ammonia water as a precipitator, and dropwise adding the precipitator into the mixed aqueous solution under vigorous stirring (the dropwise adding speed is kept at 1-2 drops/second). After the dropwise addition, stirring is continued for 0.5h, and then standing and precipitating are carried out for 24 h. Pumping and filtering, putting into a drying oven, drying at 120 ℃ for 24h, transferring the dried sample into a muffle furnace, and roasting at 640 ℃ for 6h to obtain ZrO2/Cs2And (3) an O catalyst.
Example 3
10g of ZrO (NO)3)2·8H2O and 0.21g cesium nitrate (CsNO)3) Dissolving in 500ml deionized water to obtain a mixed aqueous solution, measuring 18.6g of sodium bicarbonate to be dissolved in 30ml of deionized water as a precipitating agent, and dropwise adding the precipitating agent into the mixed aqueous solution under vigorous stirring (the dropping speed is kept between 1 and 2 drops per second). After the dropwise addition, stirring is continued for 0.5h, and then standing and precipitating are carried out for 24 h. Pumping and filtering, putting into a drying oven, drying at 120 ℃ for 24h, transferring the dried sample into a muffle furnace, and roasting at 540 ℃ for 6h to obtain ZrO2/Cs2And (3) an O catalyst.
Example 4
10g of ZrO (NO)3)2·8H2O and 0.35g cesium nitrate (CsNO)3) Dissolving in 500ml deionized water to obtain mixed water solution, measuring sodium carbonate 11.8g, dissolving in 30ml deionized waterAs a precipitant, the precipitant is added dropwise to the mixed aqueous solution under vigorous stirring (the dropping speed is maintained at 1 to 2 drops/sec). After the dropwise addition, stirring is continued for 0.5h, and then standing and precipitating are carried out for 24 h. Pumping and filtering, putting into a drying oven, drying at 120 ℃ for 24h, transferring the dried sample into a muffle furnace, and roasting at 640 ℃ for 6h to obtain ZrO2/Cs2And (3) an O catalyst.
Catalyst characterization
(1)BET
Using a Micromeritics ASAP2020 model automatic adsorption apparatus (N)2Adsorption-desorption method, i.e., BET method) to determine the specific surface area. The sample is degassed in vacuum at 350 ℃ for 10h, and then subjected to low-temperature N at the liquid nitrogen temperature (-196 ℃)2And (4) performing adsorption and desorption experiments, and calculating the specific surface area of the sample by using a BET equation.
Table 1 shows the results obtained with ZrO (NO)3)2Cesium nitrate and ZrO (NO) with Cs contents of 1, 3, and 5%, respectively, as starting materials3)2Zirconium-based composite metal oxide N prepared as raw material2The results were characterized by the adsorption-desorption (BET) method.
TABLE 1 ZrO at different Cesium contents2-Bi2O3BET characterization results of the composite Metal oxide
As can be seen from table 1, as the Cs content increases, the specific surface area increases first and then decreases, the pore volume increases first and then decreases, and the pore diameter gradually decreases.
(2) XRD spectrogram
The prepared catalyst was subjected to a crystal phase structure measurement of a solid powder sample on a Rigaku RINT 2000X-ray powder diffractometer (XRD) under conditions of ka monochromatic radiation of Cu (λ ═ 0.154178nm), tube voltage 40kV, tube current 40mA, and scanning range 10 to 90 °.
FIG. 1 shows the Cs contents of 1, 3, and 5% and ZrO (NO) respectively in the case of calcination at 600 ℃ with ammonia water as a precipitant3)2ZrO prepared as a starting material2The XRD spectrograms are compared, the characteristic peak of the prepared catalyst is obvious, and the crystallization is provedGood, added Cs2O and ZrO2A solid solution is formed and the incorporation of Cs does not change the crystal form.
(3) TPD spectrogram
FIG. 2 shows ZrO at various Cs contents2-Cs2NH of O-complex metal oxide3TPD spectrum, ZrO seen in FIG. 22And Cs-doped zirconia both have two desorption peaks at about 177 ℃ and 330 ℃, representing a weakly acidic site and a moderately strongly acidic site, respectively. After doping with Cs, the acid content of both acid sites decreased.
Testing of catalyst Performance
The catalytic performance test was carried out in a fixed bed reactor, nitrogen as a carrier gas, a mixture of ethanol and water was vaporized before entering the reactor, optimum reaction conditions were selected by adjusting the residence time of the reaction, the product was analyzed by gas chromatography, and the yield of the product was as shown in table 2:
TABLE 2 reaction results of Cs-doped zirconium-based composite metal oxide for catalyzing the conversion of bioethanol into ethylene and propylene
As can be seen from table 2, the Cs-doped zirconium-based composite metal oxide exhibited excellent selectivity in the reaction of catalytically converting ethanol into ethylene and propylene, with the yield of ethylene being about 46.9% and the yield of propylene being about 33.4%. And the stability is good.
FIG. 3 shows the distribution of the Cs-doped zirconium-based composite metal reaction product as a function of time, and it can be seen from FIG. 3 that the ethylene yield is still maintained at about 40% and the propylene yield is still maintained at about 30% within 100 h.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the scope of the present invention, therefore, the present invention is not limited by the appended claims.
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