摘要
为了提高高氯酸铵(AP)的热分解性能,采用蒸发诱导自组装的方法制备了Cu1/Al2O3单原子催化剂。采用X射线粉末衍射(XRD)、电感耦合等离子发射光谱(ICP‑OES)、透射电镜(TEM)、X射线吸收光谱(XAS)和X射线光电子能谱(XPS)对催化剂形貌和结构进行了表征,并利用差示扫描量热法(DSC)和热重分析法(TG)研究了其对AP热分解性能的影响。结果表明,活性金属铜以Cu—O键形式稳定在载体表面,呈现均匀的单原子分散状态,Cu负载量高达8.7%质量分数;当Cu1/Al2O3单原子催化剂用量为质量分数5%时,AP的高温分解峰温为319 ℃,与纯AP相比提前了85 ℃,催化效果明显优于前驱体Cu(NO3)2·3H2O以及常见的nano‑CuO催化剂,表明Cu1/Al2O3单原子催化剂对AP的热分解具有优异的催化作用。
图文摘要
To improve the thermal decomposition performance of ammonium perchlorate (AP), Cu1/Al2O3 single‑atom catalyst with high Cu loading of 8.7% was prepared and well characterized. Its effect on the thermal decomposition of AP was also investigated. Cu1/Al2O3 single‑atom catalyst exhibits superior catalytic performance.
关键词
高氯酸铵(AP)是当前复合固体推进剂中常用的氧化剂,一般占推进剂总质量的65%~7l%。而AP的热分解行为直接影响推进剂的点火、燃速、放热量等特性,因此降低AP的热分解温度对提高AP基固体推进剂燃烧性能有重要意
单原子催化剂(SACs)是一类活性组分以原子形式高度分散在载体表面的新型催化剂,具有均匀分散,100%金属利用率以及独特的不饱和配位环境等特点,2011年由中国科学家首次提出之
高氯酸铵,含量>99.0%,国药集团;Cu(NO3)2·3H2O,天津市大茂化学试剂厂;乙醇,天津市大茂化学试剂厂;乙酸乙酯,天津市大茂化学试剂厂,以上试剂为分析纯;Pluronic P123(Mav=5800,EO20PO70EO20),萨恩化学技术有限公司;异丙醇铝,化学纯,国药集团;Al2O3载体(自制);纳米氧化铜,金属含量99.5%,阿拉丁;质量分数67%硝酸,西陇科学股份有限公司。
XRD测试采用X′Pert‑Pro PW3040/60型X射线衍射仪,X射线的衍射源为Cu Kα靶,波长λ=0.15432 nm,测试电压为40 kV,测试电流为40 mA,扫描范围为10°~80°,扫描速度为10°·mi
活性金属铜负载量测试采用IRIS Intrepid II XSP型电感耦合等离子发射光谱仪(ICP‑OES)。
透射电镜测试采用JEM‑2100F型高分辨透射电镜(HR‑TEM),加速电压200 kV,EDS能谱采用上述透射电镜配带的EDS能谱仪;球差校正大角度环形暗场扫描透射电镜(HAADF‑STEM)型号为JEOL JEM‑ARM200F型。
X射线吸收光谱(XAS)包括扩展X射线吸收精细结构光谱(EXAFS)和K‑边X射线吸收近边结构光谱(XANES)在上海应用物理研究所,上海同步辐射光源测试。
X射线光电子能谱(XPS)(Thermo ESCALAB 250Xi型)用于测定活性金属价态。
X射线粉末衍射仪(Empyrean‑100型)用于获得的粉末XRD衍射谱图。
差示扫描量热仪DSC(Q1000型)和同步热分析仪TG(Q600型)用于AP热分解研究,试样量1~2 mg,铝质密封池,升温速率5 ℃·mi
利用蒸发诱导自组装的方法(EISA)制备Al2O3负载的单原子铜催化剂:室温下,称取0.44 g Cu(NO3)2·3H2O和2 g Pluronic P123(Mav=5800,EO20PO70EO20)溶解在20 mL乙醇中,得溶液A,另称取3.72 g异丙醇铝和3.2 mL质量分数67%硝酸同样溶解在20 mL乙醇中,得到溶液B,将A和B两溶液混合搅拌5 h,然后将混合液放入烘箱中,60 ℃蒸发溶剂。溶剂挥发完全,老化48 h得到浅绿色固体产物,将该产物放入马弗炉中空气气氛下焙烧,
采用机械研磨法制备Cu1/Al2O3和AP的混合样品:分别称取AP质量分数为2%,5%,10%的Cu1/Al2O3催化剂和1 g AP放到玛瑙研钵中,加入2 mL乙酸乙酯,常温下研磨使二者混合均匀,待溶剂挥发后再在40 ℃下真空干燥得到不同比例的Cu1/Al2O3和AP的混合样品。利用类似的方法,分别制备质量分数为5%的Al2O3和AP,Cu(NO3)2·3H2O和AP以及nano‑CuO和AP的混合样品。
采用X射线粉末衍射对载体Al2O3和催化剂Cu1/Al2O3的粉末结构进行了表征,结果如

图1 Al2O3载体和Cu1/Al2O3催化剂的粉末XRD谱图
Fig.1 Powder XRD patterns of Al2O3 and Cu1/Al2O3
利用透射电镜(TEM)对Cu1/Al2O3催化剂的形貌进行了表征分析,结果如

图2 Cu1/Al2O3催化剂的TEM和EDS图片。(a) Cu1/Al2O3催化剂的HR‑TEM图;(b) Cu1/Al2O3催化剂的HAADF‑STEM图; (c) Cu1/Al2O3催化剂EDS面扫区域图;(d‑h) Cu1/Al2O3催化剂的EDS谱图。图中圆圈代表铜单原子
Fig.2 TEM and EDS images of Cu1/Al2O3. (a) HR‑TEM images of Cu1/Al2O3; (b) HAADF‑STEM images of Cu1/Al2O3; (c) EDS mapping region of Cu1/Al2O3; (d‑h) EDS mapping images of copper, aluminium and oxygen. The circles in the figures represent the single Cu atoms
为了进一步验证催化剂中活性金属铜的存在形态,对Cu1/Al2O3催化剂进行了X射线吸收光谱(XAS)表征,结果如

a. EXAFS of Cu1/Al2O3, CuO, Cu2O and Cu foil

b. EXAFS fitting curve of Cu1/Al2O3

c. K edge XANES spectra of Cu1/Al2O3, CuO, Cu2O and Cu foil
图3 Cu1/Al2O3催化剂的X‑射线吸收光谱
Fig.3 X‑ray absorption spectra of Cu1/Al2O3

图4 Cu1/Al2O3催化剂的Cu 2p XPS谱图
Fig.4 Cu 2p XPS spectrum of Cu1/Al2O3

a. TG‑DTG curves of pure AP

b. TG‑DTG curves of AP+2% Cu1/Al2O3

c. TG‑DTG curves of AP+5% Cu1/Al2O3

d. TG‑DTG curves of AP+10% Cu1/Al2O3

e. DSC curves
图5 不同含量Cu1/Al2O3催化剂与AP混合物的TG‑DTG和DSC曲线
Fig.5 TG‑DTG and DSC curves for mixtures of AP and single‑atom Cu1/Al2O3 catalyst with different contents

a. TG‑DTG curves of AP+5% Al2O3

b. TG‑DTG curves of AP+5% Cu(NO3)2•3H2O

c. TG‑DTG curves of AP+5% nano‑Cu

d. DSC curves for mixtures of AP with different catalysts
图6 不同种类催化剂与AP混合物的TG‑DTG和DSC曲线
Fig.6 TG‑DTG and DSC curves for mixtures of AP with different catalysts
为了进一步评估单原子Cu1/Al2O3催化剂的催化活性,在相似的DSC测试条件下,将其与最近报道的铜纳米催化
Note: exothermic peaks (5 ℃·mi
AP的热分解是固‑气多相反应,包括低温和高温两个分解阶段,存在分解和升华竞争过程,如反应方程
(1) |
其中,AP低温分解阶段主要是固相反应,分解快慢的决定因素是ClO
(1)采用蒸发诱导自组装的方法制备了负载量高达8.7%质量分数的Cu1/Al2O3单原子催化剂,活性金属Cu以Cu—O键稳定在载体表面,并呈现均匀的单原子分散形态。
(2)Cu1/Al2O3单原子催化剂对AP的热分解具有优异的催化作用,当其用量仅为质量分数5%时,AP的高温热分解峰温提前了85 ℃,催化效果明显优于催化剂前体Cu(NO3)2·3H2O以及常见的nano‑CuO催化剂。
(3)Cu1/Al2O3单原子催化剂大大提高了金属利用率,增加了催化剂活性位点数量,降低了活性金属用量,对提高AP基固体推进剂的燃烧性能有一定的理论和应用价值。
参考文献
刘子如, 施震灏, 阴翠梅, 等. 热红联用研究AP与RDX和HMX混合体系的热分解[J]. 火炸药学报, 2007, 30(5): 57-61. [百度学术]
LIU Zi‑ru, SHI Zhen‑hao, YIN Cui‑mei, et al. Investigation on thermal decompostion of mixed systems of AP with RDX and HMX by DSC‑TG‑FTIR[J]. Chinese Journal of Explosives and Propellants, 2007, 30(5): 57-61. [百度学术]
顾克壮, 李晓东, 杨荣杰. 碳纳米管对高氯酸铵燃烧和热分解的催化作用[J]. 火炸药学报, 2006, 29(1): 48-51. [百度学术]
GU Ke‑zhuang, LI Xiao‑dong, YANG Rong‑jie. Catalytic action on combustion and thermal decomposition of AP with CNTs[J]. Chinese Journal of Explosives and Propellants, 2006, 29(1): 48-51. [百度学术]
Shusser M, Culock F E, Cohen N S. Combustion response of ammonium perchlorate composite propellants[J]. Journal of Propulsion and Power, 2012, 18(5): 1093-1100. [百度学术]
Ma Z Y, Li F S, Bai H P. Effect of Fe2O3 in Fe2O3/AP composite particles on thermal decomposition of AP and on burning rate of the composite propellant[J]. Propellants, Explosives, Pyrotechnics, 2006, 31(6): 447-451. [百度学术]
王蒙蒙, 马拥军. 花状α‑Co(OH)2的制备及其对高氯酸铵热分解的催化作用[J]. 火炸药学报, 2017, 40(3): 27-31. [百度学术]
WANG Meng‑meng, MA Yong‑jun. Synthesis of flower‑like α‑Co(OH)2 and their catalytic effect for thermal decompostion of ammonium perchlorate[J]. Chinese Journal of Explosives and Propellants, 2017, 40(3): 27-31. [百度学术]
FU Ting‑ming,LIU Fei‑quan,LIU Lin, et al. Catalytic thermal decomposition of ammonium perchlorate using manganese oxide octahedral molecular sieve (OMS)[J]. Catalysis Communications, 2008, 10(1): 108-112. [百度学术]
郝嘎子, 刘杰, 侯晓婷, 等. 纳米β‑Cu的制备及其对超细AP的催化性能[J]. 含能材料, 2015, 23(10): 947-951. [百度学术]
HAO Ga‑zi, LIU Jie, HOU Xiao‑ting, et al. Preparation of nano‑sized β‑Cu and its catalytic effects on ammonium perchlorate[J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2015, 23(10): 947-951. [百度学术]
李昊旻, 曹雄, 王保民, 等. 球磨法制备高氯酸铵基分子钙钛矿微纳米颗粒及安全性能分析[J].含能材料, 2020, 28(3): 203-207. [百度学术]
LI Hao‑min, CAO Xiong, WANG Bao‑min, et al. Preparation and safety performances of ammonium perchlorate‑based molecular perovskite micro/nano particles by ball milling [J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2020, 28(3):203-207. [百度学术]
霸书红, 才思雨, 冯璐. 金属氧化物半导体材料催化高氯酸铵热分解的研究进展[J]. 含能材料, 2021, 29(5): 460-470. [百度学术]
BA Shu‑hong, CAI Si‑yu, FENG Lu. Review on thermal decomposition of ammonium perchlorate catalyzed by metal oxide semiconductor materials[J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2021, 29(5):460-470. [百度学术]
冯杨, 何杰鑫, 鲁月文, 等. 纳米Mn3O4复合催化剂的制备及其对AP热分解性能的影响[J]. 含能材料, 2018, 26(12): 1025- 1030. [百度学术]
FENG Yang, HE Jie‑xin, LU Yue‑wen, et al. Preparation of nano‑Mn3O4 composite catalyst and it′s catalyst effect on the thermal decomposition performance of AP[J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2018, 26(12): 1025-1030. [百度学术]
董皓雪, 李国平, 张晨辉, 等. CuO/PG 纳米复合材料的制备及其对AP催化分解性能的影响[J]. 含能材料, 2018, 26(12): 1031-1037. [百度学术]
DONG Hao‑xue, LI Guo‑ping, ZHANG Chen‑hui, et al. Preparation of CuO/PG Nanocomposites and Their Effect on the Catalytic Decomposition Performance of AP [J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2018, 26(12): 1031-1037. [百度学术]
QIAO Bo‑tao, WANG Ai‑qin, YANG Xiao‑feng, et al. Single‑atom catalysis of CO oxidation using Pt1/FeOx[J]. Nature Chemistry, 2011, 3(8): 634-641. [百度学术]
Yang Xiao‑feng, Wang Ai‑qin, Qiao Bo‑tao, et al. Single‑atom catalysts: A new frontier in heterogeneous catalysis[J]. Accounts of Chemical Research, 2013, 46(8): 1740-1748. [百度学术]
Shan J, Li M, Allard L F, et al. Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts [J]. Nature, 2017, 551(7682): 605-608. [百度学术]
Lin L, Zhou W, Gao R, et al. Low‑temperature hydrogen production from water and methanol using Pt/α‑MoC catalysts [J]. Nature, 2017, 544(7648): 80-83. [百度学术]
Long R, Li Y, Liu Y, et al. Isolation of Cu atoms in Pd lattice: forming highly selective sites for photocatalytic conversion of CO2 to CH4[J]. Journal of The American Chemical Society, 2017, 139(12): 4486-4492. [百度学术]
LI Zhi, JI Shu‑fang, LIU Yi‑wei, et al. Well‑defined materials for heterogeneous catalysis: from nanoparticles to isolated single‑atom sites[J]. Chemical Review, 2020, 120(2): 623-682. [百度学术]
JI Shu‑fang, Chen Yuan‑jun, Wang Xiao‑lu, et al. Chemical Synthesis of Single atomic site catalysts[J]. Chemical Review, 2020, 120(21): 11900-11955. [百度学术]
Liu W, Chen Y, Qi H, et al. A durable nickel single‑atom catalyst for hydrogenation reactions and cellulose valorization under harsh conditions[J]. Angewante Chemie International Edition, 2018, 57(24): 7071-7075. [百度学术]
Li J, Chen S, Yang N, et al. Ultrahigh‑loading zinc single‑atom catalyst for highly efficient oxygen reduction in both acidic and alkaline media[J]. Angewante Chemie International Edition, 2019, 58(21): 7035-7039. [百度学术]
GUO Teng‑long, TANG Nan‑fang, LIN Feng, et al. High loading single‑atom catalyst supported on coordinatively unsaturated for selective synthesis of homoallylboronates[J]. Chem Sus Chem, 2020, 13(12): 3115-3121. [百度学术]
Wagner C D, Riggs W M, Davis L E, et al. Hand book of X‑ray photoelectron spectroscopy [M]. Eden Prairie: Perkin‑Elmer Corporation, 1979: 82-83. [百度学术]
Abdel‑Mageed A, Rungtaweevoranit B, Parlinska‑Wojtan M, et al. Highly active and stable single‑atom Cu catalysts supported by a metal‑organic framework[J]. Journal of the American Chemical Society, 2019, 141(13): 5201-5210. [百度学术]
Gromov A, Strokova Y, Kabardin A, et al. Experimental study of the effect of metal nanopowders on the decomposition of HMX, AP and AN[J]. Propellants, Explosives, Pyrotechnics, 2009, 34(6): 506-512. [百度学术]
Liu L, Li F, Tan L, et al. Effects of nanometer Ni, Cu, Al and NiCu powders on the thermal decomposition of ammonium perchlorate[J]. Propellants, Explosives, Pyrotechnics, 2004, 29(1): 34-38. [百度学术]
石晓琴,江晓红,陆路德,等. 铜/纳米金刚石复合物的结构及其对高氯酸铵热分解的催化作用[J]. 无机化学学报, 2006, 22(2): 316-320. [百度学术]
SHI Xiao‑qin, JIANG Xiao‑hong, LU Lu‑de, et al. Cu/UDD nanocomposite: structure and catalytic performance for thermal decomposition of ammonium perchlorate[J]. Chinese Journal of Inorgnic Chemistry, 2006, 22(2): 316-320. [百度学术]
Singh G, Kapoor IPS, Dubey S, et al. Effect of mixed ternary transition metal ferrites nanocrystallites on the thermal decomposition of ammonium perchlorates[J]. Thermo Chimica Acta, 2008, 477(1): 42-47. [百度学术]