Synthesis of Co3O4/WO3 composite catalysts for visible-light-driven conversion of methane to methanol
-
摘要: 本研究通过水热合成法并结合表面浸渍过程制备了Co3O4/WO3复合催化剂,采用X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、透射电镜(TEM)、紫外-可见吸收光谱等测试技术对Co3O4/WO3复合物的结构组成与微观形貌进行系统表征,在室温可见光照射下研究了Co3O4/WO3对甲烷转化制甲醇的催化性能。结果表明,复合Co3O4可显著提升甲烷光催化转化性能,最优催化剂3.0% Co3O4/WO3在可见光照射2 h时的甲烷转化量为2041 μmol/g,对应的甲醇产生量及其选择性为1194 μmol/g和58.5%,分别为单一WO3的4.03倍和2.39倍,优于多数文献报道的甲烷转化异相光催化剂,且具有良好的循环稳定性。结合瞬态光电流与电子顺磁共振测试结果,揭示了引入Co3O4增强复合催化剂甲烷转化性能的内在机理,对设计光驱动甲烷转化制甲醇催化剂具有重要理论指导意义。Abstract: Direct and selective conversion of methane to methanol under mild conditions still faces grand challenges. In this study, Co3O4/WO3 nanocomposite catalysts were synthesized by facile hydrothermal method, combining with surface impregnation process. The structural composition and micro morphology of Co3O4/WO3 composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and UV-visible absorption spectrum. The catalytic performance of Co3O4/WO3 on the conversion of methane to methanol was investigated under visible light illumination at room temperature. The results show that incorporating Co3O4 can remarkably improve the photocatalytic performance of methane conversion. The optimal catalyst 3.0% Co3O4/WO3 exhibits a methane conversion of 2041 μmol/g after visible light irradiation for 2 h, and the according methanol productivity and selectivity reach 1194 μmol/g and 58.5%, which are 4.03 and 2.39 times of single WO3 respectively. This performance is superior to most reported heterogeneous photocatalysts for methane conversion, meanwhile possessing excellent cyclic stability. Combining the results of transient photocurrent and electron paramagnetic resonance (EPR) with the catalytic activity, the intrinsic mechanism of enhanced methane conversion via introducing Co3O4 is revealed, which is of theoretical significance to design light-driven catalysts for methane conversion to methanol.
-
Key words:
- methane /
- visible light catalysis /
- methanol /
- tungsten oxide /
- Co3O4
-
图 6 Co3O4/WO3光催化体系的(a)甲烷转化量、甲醇产生量及其选择性,(b)副产物乙烷与CO2生成量
Figure 6 (a) Methane conversion, methanol productivity and selectivity, (b) byproduct C2H6 and CO2 productivity in Co3O4/WO3 photocatalytic system Reaction conditions: 20 mg catalyst, H2O2 concentration 3.0 mmol/L, irradiation time 2 h, 300 W Xenon lamp with filter (420 < λ < 780 nm light intensity 100 mW/cm2)
图 7 H2O2浓度与入射光强对甲烷转化、产物生成与甲醇选择性的影响
Figure 7 Effects of H2O2 concentration and light intensity on CH4 conversion, products generation and CH3OH selectivity Reaction conditions: 20 mg catalyst, irradiation time 2 h, experimental temperature (20 ±1) ℃, 300 W Xenon lamp with filter (420 nm < λ < 780 nm)
表 1 光催化转化甲烷制甲醇各种催化剂的性能
Table 1 Performance comparison of various catalysts for photocatalytic conversion of methane to methanol
Photocatalyst CH3OH yield/(μmol·g−1) CH3OH selectivity/% Ref. Au/BP nanosheets 113.5 99 [14] La doped WO3 63 46 [18] Mesoporous WO3/FeCl3 135 59 [19] FeOx/TiO2 1056 90 [27] Bi2WO6 flowers 15 28 [34] Bipyramid BiVO4 112 85 [11] FeOOH/Li0.1WO3 342 55 [35] Bi-V-BEA zeolite 22 76 [36] g-C3N4@Cs0.33WO3 4 51 [37] 3.0% Co3O4/WO3 1194 58.5 this work -
[1] MCFARLAND E. Unconventional chemistry for unconventional natural gas[J]. Science,2012,338(6105):340−342. doi: 10.1126/science.1226840 [2] SCHWACH P, PAN X L, BAO X H. Direct conversion of methane to value-added chemicals over heterogeneous catalysts: Challenges and prospects[J]. Chem Rev,2017,117(13):8497−8520. doi: 10.1021/acs.chemrev.6b00715 [3] ZHAN C G, NICHOLS J A, DIXON D A. Ionization potential, electron affinity, electronegativity, hardness, and electron excitation energy: Molecular properties from density functional theory orbital energies[J]. J Phys Chem A,2003,107(20):4184−4195. doi: 10.1021/jp0225774 [4] DA SILVA M J. Synthesis of methanol from methane: Challenges and advances on the multi-step (syngas) and one-step routes (DMTM)[J]. Fuel Process Technol,2016,145:42−61. doi: 10.1016/j.fuproc.2016.01.023 [5] KWON Y, KIM T Y, KWON G, YI J, LEE H. Selective activation of methane on single-atom catalyst of rhodium dispersed on zirconia for direct conversion[J]. J Am Chem Soc,2017,139(48):17694−17699. doi: 10.1021/jacs.7b11010 [6] AGARWAL N, FREAKLEY S J, MCVICKER R U, ALTHAHBAN S M, DIMITRATOS N, HE Q, MORGAN D J, JENKINS R L, WILLOCK D J, TAYLOR S H, KIELY C J, HUTCHINGS G J. Aqueous Au-Pd colloids catalyze selective CH4 oxidation to CH3OH with O2 under mild conditions[J]. Science,2017,358(6360):223−227. doi: 10.1126/science.aan6515 [7] 于贵阳. 空间场效应提升半导体光催化产氢性能研究[D]. 长春: 吉林大学, 2019.YU Gui-yang. The study of spatial field effect on improving semiconductor photocatalytic hydrogen evolution[D]. Changchun: Jilin University, 2019. [8] YANG J, HAO J Y, XU S Y, WANG Q, DAI J, ZHANG A C, PANG X C. InVO4/β-AgVO3 nanocomposite as a direct Z-Scheme photocatalyst toward efficient and selective visible-light-driven CO2 reduction[J]. ACS Appl Mater Inter,2019,11(35):32025−32037. doi: 10.1021/acsami.9b10758 [9] LI H, SHANG J, AI Z H, ZHANG L Z. Efficient visible light nitrogen fixation with BiOBr nanosheets of oxygen vacancies on the exposed {001} facets[J]. J Am Chem Soc,2015,137(19):6393−6399. doi: 10.1021/jacs.5b03105 [10] 许振民, 卞振锋. 光催化甲烷转化研究进展[J]. 物理化学学报,2020,36(3):1907013. doi: 10.3866/PKU.WHXB201907013XU Zhen-min, BIAN Zhen-feng. Photocatalytic methane conversion[J]. Acta Phys-Chim Sin,2020,36(3):1907013. doi: 10.3866/PKU.WHXB201907013 [11] ZHU W L, SHEN M K, FAN G Z, YANG A, MEYER J R, OU Y N, YIN B, FORTNER J, FOSTON M, LI Z S, ZOU Z G, SADTLER B. Facet-dependent enhancement in the activity of bismuth vanadate microcrystals for the photocatalytic conversion of methane to methanol[J]. ACS Appl Nano Mater,2018,1(12):6683−6691. doi: 10.1021/acsanm.8b01490 [12] LIU H S, SONG C J, ZHANG L, ZHANG J J, WANG H J, WILKINSON D P. A review of anode catalysis in the direct methanol fuel cell[J]. J Power Sources,2006,155(2):95−110. doi: 10.1016/j.jpowsour.2006.01.030 [13] SONG H, MENG X G, WANG S Y, ZHOU W, WANG X S, KAKO T, YE J H. Direct and selective photocatalytic oxidation of CH4 to oxygenates with O2 on cocatalysts/ZnO at room temperature in water[J]. J Am Chem Soc,2019,141(51):20507−20515. doi: 10.1021/jacs.9b11440 [14] LUO L H, LUO J, LI H L, REN F N, ZHANG Y F, LIU A D, LI W-X, ZENG J. Water enables mild oxidation of methane to methanol on gold single-atom catalysts[J]. Nat Commun,2021,12:1218. doi: 10.1038/s41467-021-21482-z [15] YU L H, SHAO Y, LI D Z. Direct combination of hydrogen evolution from water and methane conversion in a photocatalytic system over Pt/TiO2[J]. Appl Catal B: Environ,2017,204:216−223. doi: 10.1016/j.apcatb.2016.11.039 [16] 詹瑛瑛, 康亮, 周玉常, 蔡国辉, 陈崇启, 江莉龙. 镁助剂改性Pd/Al2O3甲烷催化燃烧催化剂: Mg/Al物质的量比对催化剂载体及活性物种形成的影响[J]. 燃料化学学报,2019,47(10):1235−1244. doi: 10.3969/j.issn.0253-2409.2019.10.010ZHAN Ying-ying, KANG Liang, ZHOU Yu-chang, CAI Guo-hui, CHEN Chong-qi, JIANG Li-long. Pd/Al2O3 catalysts modified with Mg for catalytic combustion of methane: Effect of Mg/Al mole ratios on the supports and active PdOx formation[J]. J Fuel Chem Technol,2019,47(10):1235−1244. doi: 10.3969/j.issn.0253-2409.2019.10.010 [17] 杨欢, 王桂赟, 田伟松, 童春杰. 单斜相WO3的水热合成及其光催化性能的研究[J]. 燃料化学学报,2018,46(11):1359−1369. doi: 10.3969/j.issn.0253-2409.2018.11.010YANG Huan, WANG Gui-yun, TIAN Wei-song, TONG Chun-jie. Hydrothermal synthesis of monoclinic WO3 and its photocatalytic hydrogen production performance[J]. J Fuel Chem Technol,2018,46(11):1359−1369. doi: 10.3969/j.issn.0253-2409.2018.11.010 [18] VILLA K, MURCIA-LÓPEZ S, MORANTE J R, ANDREU T. An insight on the role of La in mesoporous WO3 for the photocatalytic conversion of methane into methanol[J]. Appl Catal B: Environ,2016,187:30−36. doi: 10.1016/j.apcatb.2016.01.032 [19] VILLA K, MURCIA-LÓPEZ S, ANDREU T, MORANTE J R. Mesoporous WO3 photocatalyst for the partial oxidation of methane to methanol using electron scavengers[J]. Appl Catal B: Environ,2015,163:150−155. doi: 10.1016/j.apcatb.2014.07.055 [20] 王冰, 赵美明, 周勇, 闫世成, 邹志刚. 光催化还原二氧化碳制备太阳燃料研究进展及挑战[J]. 中国科学: 技术科学,2017,47(3):286−296. doi: 10.1360/N092016-00434WANG Bing, ZHAO Mei-ming, ZHOU Yong, YAN Shi-cheng, ZOU Zhi-gang. Recent progress and challenge in research of photocatalytic reduction of CO2 to solar fuels[J]. Sci Sin Tech,2017,47(3):286−296. doi: 10.1360/N092016-00434 [21] 孙尚聪, 张旭雅, 刘显龙, 潘伦, 张香文, 邹吉军. 光催化全解水助催化剂的设计与构建[J]. 物理化学学报,2020,36(3):1905007. doi: 10.3866/PKU.WHXB201905007SUN Shang-cong, ZHANG Xu-ya, LIU Xian-long, PAN Lun, ZHANG Xiang-wen, ZOU Ji-jun. Design and construction of cocatalysts for photocatalytic water splitting[J]. Acta Phys-Chim Sin,2020,36(3):1905007. doi: 10.3866/PKU.WHXB201905007 [22] 陈鹏, 周莹, 董帆. 二维光催化材料电子结构和性能调控策略研究进展[J]. 物理化学学报,2021,37(8):2010010.CHEN Peng, ZHOU Ying, DONG Fan. Advances in regulation strategies for electronic structure and performance of two-dimensional photocatalytic materials[J]. Acta Phys-Chim Sin,2021,37(8):2010010. [23] WANG Z D, CHU Z, DONG C W, WANG Z, YAO S Y, GAO H, LIU Z Y, LIU Y, YANG B, ZHANG H. Ultrathin BiOX (X=Cl, Br, I) nanosheets with exposed {001} facets for photocatalysis[J]. ACS Appl Nano Mater,2020,3(2):1981−1991. doi: 10.1021/acsanm.0c00022 [24] 周文君, 沈伯雄, 张芹, 王欣怡, 卢凤菊. 负载CuO的Ti3+/TiO2催化剂制备及其光催化甲苯降解性能[J]. 燃料化学学报,2019,47(2):249−256. doi: 10.3969/j.issn.0253-2409.2019.02.015ZHOU Wen-jun, SHEN Bo-xiong, ZHANG Qin, WANG Xin-yi, LU Feng-ju. Preparation of the Ti3+/TiO2 supported CuO catalyst and its photocatalytic performance in the degradation of toluene[J]. J Fuel Chem Technol,2019,47(2):249−256. doi: 10.3969/j.issn.0253-2409.2019.02.015 [25] LIU J, KE J, LI Y, LIU B J, WANG L D, XIAO H N, WANG S B. Co3O4 quantum dots/TiO2 nanobelt hybrids for highly efficient photocatalytic overall water splitting[J]. Appl Catal B: Environ,2018,236:396−403. doi: 10.1016/j.apcatb.2018.05.042 [26] YANG J, WEN Z H, SHEN X X, DAI J, LI Y, LI Y J. A comparative study on the photocatalytic behavior of graphene-TiO2 nanostructures: Effect of TiO2 dimensionality on interfacial charge transfer[J]. Chem Eng J,2018,334:907−921. doi: 10.1016/j.cej.2017.10.088 [27] XIE J J, JIN R X, LI A, BI Y P, RUAN Q S, DENG Y C, ZHANG Y J, YAO S Y, SANKAR G, MA D, TANG J W. Highly selective oxidation of methane to methanol at ambient conditions by titanium dioxide-supported iron species[J]. Nat Catal,2018,1(11):889−896. doi: 10.1038/s41929-018-0170-x [28] MA M, ZHANG K, LI P, JUNG M S, JEONG M J, PARK J H. Dual oxygen and tungsten vacancies on a WO3 photoanode for enhanced water oxidation[J]. Angew Chem Int Ed,2016,55(39):11819−11823. doi: 10.1002/anie.201605247 [29] LIU D N, CHEN D Y, LI N J, XU Q F, LI H, HE J H, LU J M. ZIF-67-derived 3D hollow mesoporous crystalline Co3O4 wrapped by 2D g-C3N4 nanosheets for photocatalytic removal of nitric oxide[J]. Small,2019,15(31):1902291. doi: 10.1002/smll.201902291 [30] ZHANG H Y, GUO C F, REN J B, NING J Q, ZHONG Y J, ZHANG Z Y, HU Y. Beyond CoOx: A versatile amorphous cobalt species as an efficient cocatalyst for visible-light-driven photocatalytic water oxidation[J]. Chem Commun,2019,55(93):14050−14053. doi: 10.1039/C9CC07835E [31] PARK J, YOON H, CHOI S, SON J. Nanoscaffold WO3 by kinetically controlled polymorphism[J]. Cryst Growth Des,2019,19(1):479−486. doi: 10.1021/acs.cgd.8b01551 [32] LIU H, ZHANG J, AO D. Construction of heterostructured ZnIn2S4@NH2-MIL-125(Ti) nanocomposites for visible-light-driven H2 production[J]. Appl Catal B: Environ,2018,221:433−442. doi: 10.1016/j.apcatb.2017.09.043 [33] YUAN J L, WEN J Q, GAO Q Z, CHEN S C, LI J M, LI X, FANG Y P. Amorphous Co3O4 modified CdS nanorods with enhanced visible-light photocatalytic H2-production activity[J]. Dalton Trans,2015,44(4):1680−1689. doi: 10.1039/C4DT03197K [34] MURCIA-LÓPEZ S, VILLA K, ANDREU T, MORANTE J R. Partial oxidation of methane to methanol using bismuth-based photocatalysts[J]. ACS Catal,2014,4:3013−3019. doi: 10.1021/cs500821r [35] ZENG Y, LUO X, LI F, HUANG A H, WU H M, XU G Q, WANG S L. Noble metal-free FeOOH/Li0.1WO3 core-shell nanorods for selective oxidation of methane to methanol with Visible-NIR light[J]. Environ Sci Technol,2021,55(11):7711−7720. doi: 10.1021/acs.est.1c01152 [36] MURCIA-LÓPEZ S, BACARIZA M C, VILLA K, LOPES J M, HENRIQUES C, MORANTE J R, ANDREU T. Controlled photocatalytic oxidation of methane to methanol through surface modification of beta zeolites[J]. ACS Catal,2017,7:2878−2885. doi: 10.1021/acscatal.6b03535 [37] LI Y, LI J, ZHANG G K, WANG K, WU X Y. Selective photocatalytic oxidation of low concentration methane over graphitic carbon nitride-decorated tungsten bronze cesium[J]. ACS Sustainable Chem Eng,2019,7(4):4382−4389. doi: 10.1021/acssuschemeng.8b06270 [38] CHEN Z Q, CHEN P F, XING P X, HU X, LIN H J, ZHAO L H, WU Y, HE Y M. Rapid fabrication of KTa0.75Nb0.25/g-C3N4 composite via microwave heating for efficient photocatalytic H2 evolution[J]. Fuel,2019,241:1−11. doi: 10.1016/j.fuel.2018.12.011 [39] 成荣敏, 徐虹, 单瑞平, 詹从红. La掺杂钛酸钙光催化剂在可见光下分解水制氢的影响因素[J]. 高等学校化学学报,2020,41(6):1345−1351. doi: 10.7503/cjcu20190644CHENG Rong-min, XU Hong, SHAN Rui-ping, ZHAN Cong-hong. Influential factors of La-doped Calcium Titanate for photocatalytic H2 evolution under visible light[J]. Chem J Chin Univ,2020,41(6):1345−1351. doi: 10.7503/cjcu20190644 [40] ZHAO Z W, FAN J Y, DENG X Y, LIU J. One-step synthesis of phosphorus-doped g-C3N4/Co3O4 quantum dots from vitamin B12 with enhanced visible-light photocatalytic activity for metronidazole degradation[J]. Chem Eng J,2019,360:1517−1529. doi: 10.1016/j.cej.2018.10.239 [41] TANG C N, LIU E Z, WAN J, HU X Y, FAN J. Co3O4 nanoparticles decorated Ag3PO4 tetrapods as an efficient visible-light-driven heterojunction photocatalyst[J]. Appl Catal B: Environ,2016,181:707−715. doi: 10.1016/j.apcatb.2015.08.045 [42] HE W W, KIM H K, WARNER W G, MELKA D, CALLAHAN J H, YIN J J. Photogenerated charge carriers and reactive oxygen species in ZnO/Au hybrid nanostructures with enhanced photocatalytic and antibacterial activity[J]. J Am Chem Soc,2014,136:750−757. doi: 10.1021/ja410800y