Regulation of Co2+ cations on the content of Brönsted acid site and oxygen vacancy of WOx to improve the epoxidation performance of 1-hexene
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摘要: 本研究采用动态溶剂热合成法,在WOx的制备过程中直接引入Co2+得到了Co-WOx催化剂,并将其用于1-己烯的催化环氧化。通过XRD、SEM、TEM、Raman、XPS等多种表征手段以及原位NH3-FTIR对Co2+引入前后WOx的结构进行了系统分析。结果表明,Co2+的引入对WOx的晶型和晶体主生长方向无明显影响,但有效减少了其表面Brönsted酸(B酸)含量,同时增加了其表面氧空位含量。在环氧化反应中,所得Co-WOx催化剂(Co/W=0.1)在1-己烯转化率降低5.3%的情况下,可以将1,2-环氧己烷的选择性从纯WOx的26.9%提高至55.7%。Co-WOx催化剂环氧化性能的提高主要归因于两个方面:一是,WOx表面B酸位点减少抑制了1,2-环氧己烷的开环水解;二是,WOx表面氧空位增多促进了H2O2的活化,保证了1-己烯转化率降幅不大,而且使氧化剂H2O2的利用率提高了13.5%。结合表征结果和反应数据,提出了以W−O−OH为活性中间体的1-己烯环氧化反应机理。
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关键词:
- WOx /
- Co2+掺杂 /
- Brönsted酸位 /
- 氧空位 /
- 1-己烯环氧化
Abstract: In this study, the Co-WOx catalyst was successfully prepared by directly introducing Co2+ dopant in a dynamic solvothermal synthesis process, and the obtained Co-WOx was used for the catalytic epoxidation of 1-hexene. The structures of WOx before and after the doping were analyzed by XRD, SEM, TEM, Raman, XPS as well as in-situ NH3-FTIR. The results show that the doping of Co2+ has not obvious effect on the crystal phase and main growth direction of WOx, but can effectively reduce the content of Brönsted acid (B acid) site on the surface of WOx catalyst and increase the content of oxygen vacancy at the same time. In the epoxidation reaction, the obtained Co-WOx catalyst (Co/W = 0.1) can increase the selectivity of 1,2-epoxyhexane from 26.9% of pure WOx to 55.7% with a 5.3% decrease in 1-hexene conversion. The improvement of Co-WOx performance is mainly attributed to two aspects: (1) the reduction of B acid site on the surface of WOx inhibits the ring opening hydrolysis of 1,2-epoxyhexane; (2) The increase of oxygen vacancies on the surface of WOx promotes the activation of H2O2, ensuring that the conversion rate of 1-hexene does not decrease significantly, and an increase in the utilization of oxidant H2O2 by 13.5%. Combined with the characterization results and reaction data, the epoxidation mechanism of 1-hexene with W−O−OH as active intermediate is proposed.-
Key words:
- WOx /
- Co doping /
- Brönsted acid site /
- oxygen vacancies /
- 1-hexene epoxidation
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表 1 纯WOx和Co-WOx-0.1的原位NH3-FTIR峰面积
Table 1 In-situ NH3-FTIR peak areas of pure WOx and Co-WOx-0.1
t/℃ WOx Co-WOx-0.1 AL AB AL/AB AL AB AL/AB 70 ℃ 1.92 5.00 0.38 7.20 5.51 0.77 100 ℃ 0.93 3.88 0.24 4.67 2.71 0.58 150 ℃ 0.55 2.75 0.20 5.08 2.05 0.40 200 ℃ 0.39 1.96 0.19 1.45 0.50 0.34 250 ℃ 0.20 1.75 0.11 1.42 0.45 0.32 表 2 H2O2的利用率和转化率
Table 2 Utilization rate and conversion rate of H2O2
Catalyst(0.05 g) Co-WOx-0.1 WOx n(H2O2):n(1-hexene) 0.5∶1 1∶1 2∶1 3∶1 1:1 H2O2 n/% 14.8 21.4 11.6 7.9 12.1 H2O2 x/% 18.5 25.63 53.6 61.8 22.5 -
[1] BREGANTE D T, FLAHERTY D W. Periodic trends in olefin epoxidation over group IV and V framework-substituted zeolite catalysts: A kinetic and spectroscopic study[J]. J Am Chem Soc,2017,139(20):6888−6898. doi: 10.1021/jacs.7b01422 [2] BREGANTE D T, PRIYADARSHINI P, FLAHERTY D W. Kinetic and spectroscopic evidence for reaction pathways and intermediates for olefin epoxidation on Nb in *BEA[J]. J Catal,2017,348:75−89. doi: 10.1016/j.jcat.2017.02.008 [3] JIN K, MAALOUF J H, LAZOUSKI N, CORBIN N, YANG D T, MANTHIRAM K. Epoxidation of cyclooctene using water as the oxygen atom source at manganese oxide electrocatalysts[J]. J Am Chem Soc,2019,141(15):6413−6418. doi: 10.1021/jacs.9b02345 [4] DISSANAYAKE S, VORA N, ACHOLA L, DANG Y L, HE J K, TOBIN Z, LU X X, MIRICH A, GAO P X, SUIB S L. Synergistic catalysis by Mn promoted ceria for molecular oxygen assisted epoxidation[J]. Appl Catal B: Environ,2021,282:119573−119584. doi: 10.1016/j.apcatb.2020.119573 [5] DEMENT’EV K I, SAGARADZE A D, KUZNETSOV P S, PALANKOEC T A. Selective production of light olefins from fischer–tropsch synthetic oil by catalytic cracking[J]. Ind Eng Chem Res,2020,59(36):15875−15883. doi: 10.1021/acs.iecr.0c02753 [6] SMIT E D, WECKHUYSEN B M. The renaissance of iron-based Fischer-Tropsch synthesis: on the multifaceted catalyst deactivation behaviour[J]. Chem Soc Rev,2008,37(12):2758−81. doi: 10.1039/b805427d [7] GALVIS H T, JONG K D. Catalysts for production of lower olefins from synthesis gas: A review[J]. ACS Catal,2013,3(9):2130−2149. doi: 10.1021/cs4003436 [8] ZHAI P, XU C, GAO R, LIU X, LI M Z, LI W Z, FU X P, JIA C J, XIE J L, ZHAO M, WANG X P, LI Y W, ZHANG Q W, WEN X D, MA D. Highly tunable selectivity for syngas-derived alkenes over zinc and sodium-modulated Fe5C2 catalyst[J]. Angew Chem Int Ed,2016,128:10056−10061. doi: 10.1002/ange.201603556 [9] 李德宝, 肖勇, 谭光军, 张国权, 廖廷君, 李勇, 贾丽涛, 陈从标. 一种合成长链α-烯烃的催化剂及其制备方法和应用: 中国, 2020104860290[P]. 2020-08-14.LI De-bao, XIAO Yong, TAN Guang-jun, ZhANG Guo-quan, LIAO Yan-jun, LI Yong, JIA Li-tao, CHEN Cong-biao. A catalyst for synthesizing long-chain alpha-olefins A catalyst for synthesizing long-chain alpha-olefins, its preparation method and application agent, and its preparation method and application: CN, 2020104860290[P]. 2020-08-14 [10] 林栋, 冯翔, 刘熠斌, DE Chen, 杨朝合. 钛硅分子筛催化剂高效钛位点的理性构筑与调控及催化烯烃环氧化的性能[J]. 中国科学: 化学, https://kns.cnki.net/kcms/detail/11.5838.O6.20220124.1411.002.html.LIN Dong, FENG Xiang, LIU Yi-bin, DE Chen, YANG Chao-he. Rational construction and regulation of efficient titanium sites on titanium-silicon molecular sieve catalysts and their catalytic performance for olefin epoxidation[J]. Sci China Chem, https://kns.cnki.net/kcms/detail/11.5838.O6.20220124.1411.002.html. [11] 常慧. 烯烃环氧化技术及其催化剂发展概述[J]. 石油化工技术与经济,2015,31(6):45−49. doi: 10.3969/j.issn.1674-1099.2015.06.012CHANG Hui. Overview of olefin epoxidation technology and its catalyst development[J]. Technol Econ Petrochem,2015,31(6):45−49. doi: 10.3969/j.issn.1674-1099.2015.06.012 [12] 张术栋, 徐成华, 冯良荣, 邱发礼. 烯烃环氧化及其催化剂的研究进展[J]. 合成化学,2003,11(4):294−299.ZHANG Shu-dong, XU Cheng-hua, FENG Liang-rong, QIU Fa-li. Progress of alkene epoxidation and its catalysts[J]. Chin J Syn Chem,2003,11(4):294−299. [13] LIANG J, ZHANG Q, WU H, MENG G, TANG Q, WANG Y. Iron-based heterogeneous catalysts for epoxidation of alkenes using molecular oxygen[J]. Catal Commun,2004,5(11):665−669. doi: 10.1016/j.catcom.2004.08.010 [14] AYLA E Z, POTTS D S, BREGANTE D T, FLAHERTY D W. Alkene epoxidations with H2O2 over groups 4–6 metal-substituted bea zeolites: reactive intermediates, reaction pathways, and linear free-energy relationships[J]. ACS Catal,2020,11(1):139−154. [15] SONG J, HUANG Z F, PAN L, ZOU J J, ZHANG X W, WANG L. Oxygen-deficient tungsten oxide as versatile and efficient hydrogenation catalyst[J]. ACS Catal,2015,5(11):6594−6599. doi: 10.1021/acscatal.5b01522 [16] WU P, TATSUMI T, KOMATSU T, YASHIMA T. A novel titanosilicate with MWW structure: II. catalytic properties in the selective oxidation of alkenes[J]. J Catal,2001,202(2):245−255. doi: 10.1006/jcat.2001.3278 [17] AHMADI M, MISTRY H, ROLDAN CUENYA B. Tailoring the catalytic properties of metal nanoparticles via support interactions[J]. J Phys Chem Lett,2016,7(17):3519−3533. doi: 10.1021/acs.jpclett.6b01198 [18] LOULOUDI M, KOLOKYTHA C, HADJILIADIS N. Alkene epoxidation catalysed by binuclear manganese complexes[J]. J Mol Catal A,2002,180(1/2):19−24. [19] ZHENG H, OU J Z, STRANO M S, KANER R B, MITCHELL A, KALANTAR-ZADEH K. Nanostructured tungsten oxide-properties, synthesis, and applications[J]. Adv Funct Mater,2011,21(12):2175−2196. doi: 10.1002/adfm.201002477 [20] LIU H, HUANG S, ZHANG L, LIU S L, XIN W J, XU L Y. The preparation of active WO3 catalysts for metathesis between ethene and 2-butene under moist atmosphere[J]. Catal Commun,2009,10(5):544−548. doi: 10.1016/j.catcom.2008.10.030 [21] MA J, ZHANG J, WANG S R, WANG T H, LIAN J B, DUAN X C, ZHENG W J. Topochemical preparation of WO3 nanoplates through precursor H2WO4 and their gas-sensing performances[J]. J Phys Chem C,2011,115(37):18157−18163. doi: 10.1021/jp205782a [22] AN X, YU J C, WANG Y, HU Y M, YU X L, ZHANG G J. WO3 nanorods/graphene nanocomposites for high-efficiency visible-light-driven photocatalysis and NO2 gas sensing[J]. J Mater Chem,2012,22(17):8525−8531. doi: 10.1039/c2jm16709c [23] GHOSH S, ACHARYYA S S, KUMAR M, BAL R. One-pot preparation of nanocrystalline Ag-WO3 catalyst for the selective oxidation of styrene[J]. RSC Adv,2015,5(47):37610−37616. doi: 10.1039/C5RA03803K [24] ZHANG M, SINGH V, HU X, MA X Y, LU J K, ZHANG C, WANG J P, NIU J Y. Efficient olefins epoxidation on ultrafine H2O-WOx nanoparticles with spectroscopic evidence of intermediate species[J]. ACS Catal,2019,9(9):7641−7650. doi: 10.1021/acscatal.9b01226 [25] MAHESEWRI R, PACHAMUTHU M P, RAMANATHAN A, SUBRAMANIAM B. Synthesis, characterization, and epoxidation activity of tungsten-incorporated SBA-16 (W-SBA-16)[J]. Ind Eng Chem Res,2014,53(49):18833−18839. doi: 10.1021/ie501784c [26] GAO R H, YANG X L, DAI W L, LE Y L, LI H X, FAN K N. High-activity, single-site mesoporous WO3-MCF materials for the catalytic epoxidation of cycloocta-1, 5-diene with aqueous hydrogen peroxide[J]. J Catal,2008,256(2):259−267. doi: 10.1016/j.jcat.2008.03.017 [27] SHIMA H, TATSUMI T, KONDO J N. Direct FT-IR observation of oxidation of 1-hexene and cyclohexene with H2O2 over TS-1[J]. Microporous Mesoporous Mater,2010,135(1/3):13−20. doi: 10.1016/j.micromeso.2010.06.005 [28] BORAH P, MA X, NGUYEN K T, ZHAO Y L. A vanadyl complex grafted to periodic mesoporous organosilica: A green catalyst for selective hydroxylation of benzene to phenol[J]. Angew Chem Int Ed,2012,51(31):7756−7761. doi: 10.1002/anie.201203275 [29] BU J, YUN S H, RHEE H K. Epoxidation of n-hexene and cyclohexene over titanium-containing catalysts[J]. Korean J Chem Eng,2000,17(1):76−80. doi: 10.1007/BF02789257 [30] HAMEED A, GONDAL M A, YAMANI Z H. Effect of transition metal doping on photocatalytic activity of WO3 for water splitting under laser illumination: role of 3d-orbitals[J]. Catal Commun,2004,5(11):715−719. doi: 10.1016/j.catcom.2004.09.002 [31] SONG H, LI Y G, LOU Z R, XIAO M, HU L, YE Z Z, ZHU L P. Synthesis of Fe-doped WO3 nanostructures with high visible-light-driven photocatalytic activities[J]. Appl Catal B: Environ,2015,166−167:112−120. doi: 10.1016/j.apcatb.2014.11.020 [32] FENG C, WANG S, GENG B. Ti(Ⅳ) doped WO3 nanocuboids: fabrication and enhanced visible-light-driven photocatalytic performance[J]. Nanoscale Adv,2011,3(9):3695−3699. doi: 10.1039/c1nr10460h [33] MUKHERJEE R, PRAJAPATI C S, SAHAY P P. Tin-incorporation induced changes in the microstructural, optical, and electrical behavior of tungsten oxide nanocrystalline thin films grown via spray pyrolysis[J]. J Therm Spray Technol,2014,23(8):1445−1455. doi: 10.1007/s11666-014-0134-x [34] CAO Y, WANG H X, DING R M, WANG L C, LIU Z, LV B L. Highly efficient oxidative desulfurization of dibenzothiophene using Ni modified MoO3 catalyst[J]. Appl Catal A: Gen,2020,589:117308−117317. doi: 10.1016/j.apcata.2019.117308 [35] MEHMOOD F, IQBAL J, JAN T, GUL A, MANSOOR Q, FARYAL R. Structural, photoluminescence, electrical, anti cancer and visible light driven photocatalytic characteristics of Co doped WO3 nanoplates[J]. Vib Spectrosc,2017,93:78−89. doi: 10.1016/j.vibspec.2017.09.005 [36] ABBAS F, IQBAL J, JAN T, GUL A, ABBASI R, MAHMOOD A, AHMAD I, ISMAIL M. Differential cytotoxicity of ferromagnetic Co doped CeO2 nanoparticles against human neuroblastoma cancer cells[J]. J Alloys Compd,2015,648:1060−1066. doi: 10.1016/j.jallcom.2015.06.195 [37] YU Y K, TANG Z M, WANG J, WANG R, ChEN Z, LIU H X, ShEN K X, HUANG X, LIU Y M, HE M Y. Insights into the efficiency of hydrogen peroxide utilization over titanosilicate/H2O2 systems[J]. J Catal,2020,381:96−107. doi: 10.1016/j.jcat.2019.09.045 [38] ZHANG H, HUANG C L, TAO R, ZHAO Y F, ChEN S, SUN Z Y, LIU Z M. One-pot solvothermal method to synthesize platinum/W18O49 ultrafine nanowires and their catalytic performance[J]. J Mater Chem,2012,22(8):3354−3359. doi: 10.1039/c1jm15726d [39] HE X J, YING Y, ZHAO X, DENG W F, TAN Y M, XIE Q J. Cobalt-doped tungsten trioxide nanorods decorated with Au nanoparticles for ultrasensitive photoelectrochemical detection of aflatoxin B1 based on aptamer structure switch[J]. Sens Actuators B,2021,332:1−8. [40] 辛勤, 罗孟飞. 现代催化研究方法[M]. 北京: 科学出版社, 2009.XIN Qin, LUO Meng-fei. Modern Catalytic Research Methods[M]. Beijing: Science Press, 2009. [41] GONZALEZ J, WANG J A, CHEN L F, MANRIQUEZ, M E, DOMINGUEZ J M. Structural defects, lewis acidity, and catalysis properties of mesostructured WO3/SBA-15 nanocatalysts[J]. J Phys Chem C,2017,121(43):23988−23999. doi: 10.1021/acs.jpcc.7b06373 [42] LEI Q F, WANG C, DAI W L, WU G J, GUAN N J, HUNGER M, LI L D. Tandem Lewis acid catalysis for the conversion of alkenes to 1, 2-diols in the confined space of bifunctional TiSn-Beta zeolite[J]. Chin J Catal,2021,42(7):1176−1184. doi: 10.1016/S1872-2067(20)63734-2 [43] ZHANG G Q, WANG D, FENG P, SH I S, WANG C X, ZHENG A D, LI G L, TIAN Z J. Synthesis of zeolite Beta containing ultra-small CoO particles for ethylbenzene oxidation[J]. Chin J Catal,2017,38(7):1207−1215. doi: 10.1016/S1872-2067(17)62853-5 [44] 张晓晶, 贾永芹. 分子筛负载CoOx催化剂用于苯的催化氧化[J]. 环境科学与技术,2018,41(9):28−32.ZHANG Xiao-jing, JIA Yong-qin. Catalytic oxidation of benzene over zeolites supported CoOx catalysts[J]. Environ Sci Technol,2018,41(9):28−32. [45] QIU L, CHENG Y, YANG C, ZENG G M, LONG Z Y, WEI S N, ZHAO K, LUO L. Oxidative desulfurization of dibenzothiophene using a catalyst of molybdenum supported on modified medicinal stone[J]. RSC Adv,2016,6(21):17036−17045. doi: 10.1039/C5RA23077B [46] RAMANATHAN A, ZHU H, MAHESWARI R, THAPA P S, SUBRAMANIAM B. Comparative study of Nb-Incorporated cubic mesoporous silicates as epoxidation catalysts[J]. Ind Eng Chem Res,2015,54(16):4236−4242. doi: 10.1021/ie504386g [47] YAN W J, ZHANG G Y, YAN H, LIU Y B, CHEN X B, FENG X, JIN X, YANG C H. Liquid-phase epoxidation of light olefins over W and Nb nanocatalysts[J]. ACS Sustainable Chem Eng,2018,6(4):4423−4452. doi: 10.1021/acssuschemeng.7b03101 [48] FRANCESCA BONINO A D, GABRIELE R, MARCO R, GUIDO S, RINO D, ADRIANO Z, CARLO L, CARMELO P, SILVIA B. Ti-Peroxo species in the TS-1/H2O2/H2O system[J]. J Phys Chem B,2004,108:3573−3583. doi: 10.1021/jp036166e [49] SILVIA B, ALESSANDRO D, FRANCESCA B, GABRIELE R, CARLO L, ADRIANO Z. The structure of the peroxo species in the TS-1 catalyst as investigated by resonant Raman spectroscopy[J]. Angew Chem Int Ed,2002,41(24):4734−4737. doi: 10.1002/anie.200290032 [50] YOON C W, HIRSEKORN K F, NEIDIG M L, YANG X Z, Tilley T D. Mechanism of the decomposition of aqueous hydrogen peroxide over heterogeneous TiSBA15 and TS-1 selective oxidation catalysts: Insights from spectroscopic and density functional theory studies[J]. ACS Catal,2011,1(12):1665−1678. doi: 10.1021/cs2003774 [51] BREGANTE D T, THORNBURG N E, NOTESTEIN J M, FLAHERTY D W. Consequences of confinement for alkene epoxidation with hydrogen peroxide on highly dispersed group 4 and 5 metal oxide catalysts[J]. ACS Catal,2018,8(4):2995−3010. doi: 10.1021/acscatal.7b03986 [52] SALEM I A, EL-MAAZAWI M, ZAKI A B. Kinetics and mechanisms of decomposition reaction of hydrogen peroxide in presence of metal complexes[J]. Int J Chem Kinet,2000,32(11):643−666. doi: 10.1002/1097-4601(2000)32:11<643::AID-KIN1>3.0.CO;2-C [53] NIJHUIS T A, MUSCH M, MAKKEE M, MOULIJN J. A. The direct epoxidation of propene by molten salts[J]. Appl Catal A: Gen,2000,196:217−224. doi: 10.1016/S0926-860X(99)00476-7 [54] MONNIER J R. The direct epoxidation of higher olefins using molecular oxygen[J]. Appl Catal A: Gen,2001,221:73−91. doi: 10.1016/S0926-860X(01)00799-2