Copper oxide alumina composite via template assisted sol–gel method for ammonium perchlorate decomposition

https://doi.org/10.1016/j.jiec.2017.04.020Get rights and content

Highlights

  • Mesoporous copper oxide with high catalytic activity was synthesized.

  • Activity depended upon alumina concentration.

  • Mesostructures have 5.2 nm pore diameter.

  • Better substituent for currently used systems.

Abstract

The burning characteristics of solid propellants contain ammonium perchlorate (AP) as oxidizer can be modified by the addition of burn rate modifiers (BRM). Herein, we report the synthesis of a new class of BRM based on nano copper oxide (CuO) dispersed on alumina by a sol–gel method. The optimum concentration of CuO:Al2O3 was found to be 80:20 which shows highest catalytic activity for the thermal decomposition of AP due to the good dispersion of MCO over alumina thereby exposing most of the active sites, facilitating the rapid decomposition of AP.

Introduction

Composite solid propellants (CSP) are the major source of chemical energy for satellite launch vehicles and missiles, CSP is heterogeneous mixtures consisting of an oxidizer, usually ammonium perchlorate (AP), metallic fuel like aluminum powder and a fuel-cum-binder, generally hydroxyl-terminated polybutadiene [1], [2]. In addition, they contain curing agents, plasticizers, bonding agents and deoxidizers for improving their mechanical and storage properties and burn rate modifiers for improving burning rate. The thermal decomposition and hence burning characteristics of AP is influenced by the burn rate modifiers. Mainly transition metal oxides like iron (III) oxide, cobalt (III) oxide, manganese (IV) oxide, copper (II) oxide, and mixed metal oxides like copper chromite etc. are used as these types of catalysts. The physical characteristics of the metal oxides such as particle size, surface area and defects in the crystalline structure and chemical characteristics such as oxidation state and chemical composition affect its catalytic activity. In the case of fast decomposition/combustion reaction, such as propellant combustion a catalyst with low particle size, high surface area, and high porosity is well suited [3], [4].

Since the discovery of ordered mesoporous silica (e.g., MCM-41 and SBA-15) in the early 90s, mesoporous materials have attracted much interest owing to their wide range of applications. Although numerous methods have been developed to prepare silica mesostructures, the preparation of non-silica mesoporous materials is more challenging [5], [6]. The beginning of the 21st century saw considerable progress in the preparation of ordered non-silica mesoporous metal oxides (MMO) [7], [8]. MMO have been of pivotal importance in material science and their application has been widely demonstrated in various areas, including adsorption, catalysis, energy conversion and storage, optoelectronics and biological platforms [9]. Several synthetic strategies have been developed for the preparation of MMO [10], [11], [12], [13]. Among these methods, soft-templating routes that rely on the synergistic self-assembly of surfactant and metal oxide precursor, followed by calcination, generate mesoporous metal oxides with tunable mesostructure and pore size [14], [15], [16], [17], [18].

Preparation of mesoporous transition metal oxides possessing highly porous structure and large surface area and their application in the area of catalysis are well studied [19], [20], [21], [22], [23], [24]. Among these metal oxides, copper oxide (CuO) nanoparticles attract great interest due to their outstanding and distinct features in electronics, catalysis, and photonics. However, these are also very easy to get aggregated and thereby affecting their chemical and physical properties (e.g. catalytic activity) To avoid aggregation, these nanoparticles are dispersed on a substrate which acts as an anti-agglomerating agent [25]. From the viewpoint of materials science and technology, distributing these sensitive metal oxides over the surface of an inert material would be an effective and alternative strategy [26], [27]. These dispersed nanoparticles not only acquire remarkable stability but also promote physicochemical performances, which are so attractive and fascinating that they extend the breadth of practical applications of these nanoparticles. For example, Paulose et al. have studied the effect of graphite oxide support on the distribution and catalytic activity of Fe2O3 nanoparticles and concluded that dispersing iron oxide nanoparticles on graphite oxide surface not only decreases the tendency for aggregation of iron oxide but also increases its catalytic activity [28].

However, to the best of our knowledge, the use of mesoporous copper oxide dispersed on alumina as combustion catalysts for AP decomposition has not been studied well to date. Herein, we report the synthesis of mesoporous copper oxide, dispersed on alumina by the sol–gel process using block copolymer as a template. A series of mesoporous oxides of Cu and Al were prepared with different Cu:Al ratios. These mesoporous copper oxides dispersed on alumina (MCO) were characterized by different techniques and their catalytic activity for the thermal decomposition of AP was evaluated. Attempts were made to correlate the properties of MCO's with their catalytic activity.

Section snippets

Chemicals

All chemicals used in this study are of analytical grade. Copper nitrate trihydrate, aluminum nitrate nonhydrate, (SD Fine Chemicals, India) Citric acid (Merck, India) Pluronic 123 co-polymer (Sigma-Aldrich, USA Mol. Wt 5800) were used for the synthesis of catalysts. Ammonium perchlorate made in house with purity >99% was used for studying the catalytic activity.

Preparation of copper oxide dispersed on alumina

MCO was synthesized by a solvent-evaporation-induced self-assembly method using metal nitrates as the metal source and triblock

Elemental composition

Elemental composition of the samples was estimated by volumetric titration methods and the results are tabulated in Table 1 [29]. From Table 1 it can be seen that the experimental results are well matching with the theoretical values.

Powder X-ray diffraction

The crystal phase of the mesoporous CuO nanoparticles dispersed on Al2O3 was determined by powder XRD analysis and the diffractograms are shown in Fig. 1. From Fig. 1 it can be seen that the patterns and relative intensities of all diffraction peaks are matching

Conclusions

Copper oxide–alumina composites were prepared by polymer template assisted sol–gel method. Copper oxide particle prepared by this route are mesoporous in nature with a particle size of 20–30 nm. Effect of alumina on the catalytic activity of the synthesized copper oxide was studied in detail. The final products and distribution of copper oxide particles were strongly dependent on the alumina concentration. FESEM analysis shows that as the concentration of alumina increases the size of copper

Acknowledgments

The authors thank Director, VSSC, Deputy Director (PCM), VSSC for granting permission to publish this work and colleagues in Analytical and Spectroscopy Division, VSSC for their support. One of the authors (Sanoop Paulose) acknowledges ISRO for the fellowship.

References (37)

  • V.V. Boldyrev

    Thermochim. Acta

    (2006)
  • R. Zhang et al.

    Nano Today

    (2012)
  • N. Pal et al.

    Adv. Colloid Interface Sci.

    (2013)
  • J. Park et al.

    J. Mol. Catal. A: Chem.

    (2010)
  • A. Taguchi et al.

    Microporous Mesoporous Mater.

    (2005)
  • W. Li et al.

    Solid State Sci.

    (2007)
  • R.P. Rastogi et al.

    J. Catal.

    (1980)
  • A.P. Sanoop et al.

    Themochim. Acta

    (2015)
  • W. Yue et al.

    Nat. Sci.

    (2008)
  • A. Bansiwal et al.

    Microporous Mesoporous Mater.

    (2010)
  • H. Tanaka

    Thermochim. Acta

    (1995)
  • Y.X. Zhang et al.

    Int. J. Electrochem. Sci.

    (2013)
  • A. Davenas

    Solid Rocket Propulsion Pergamon Technology

    (1993)
  • G.P. Sutton

    Rocket Propulsion Elements

    (2010)
  • P.W.M. Jacobs et al.

    Chem. Rev.

    (1969)
  • Y. Ren et al.

    Chem. Soc. Rev.

    (2012)
  • S.M. Morris et al.

    J. Am. Chem. Soc.

    (2008)
  • P. Yang et al.

    Chem. Mater.

    (1999)
  • Cited by (32)

    • Fluorocarbon nanosheet@copper oxide microspheres: Simultaneous promotion the decomposition of ammonium perchlorate and ignition performance of aluminum

      2023, Journal of Physics and Chemistry of Solids
      Citation Excerpt :

      As a result, addition of FCN@CuO/Cu2O can effectively reduce the high-temperature decomposition of AP. Meanwhile, according to previous studies, the low-temperature decomposition process of AP starts from the inside AP particles and is difficult to affect by external composite [38]. Therefore, addition of FCN@CuO/Cu2O has no effect on the low-temperature thermal decomposition of AP.

    • Design of three dimensional flower-like MXene/manganese-cobalt spinel nanocomposites for efficient catalytic thermal decomposition of ammonium perchlorate

      2021, Ceramics International
      Citation Excerpt :

      The SEM images shown inFig. 2c1 and c2 indicated that ice template method could only disperse part of nano-sized MnCo2O4.5 on MXene nanosheets, which might partly improve the dispersion of MnCo2O4.5 nanoparticles and make it unable to further improve the catalytic performance of MnCo2O4.5 [44]. Moreover, MMC-W with 3D flower-like structure might have larger specific surface area, which might make it exhibit higher catalytic performance than MMC-P and MMC-I [45]. To analyze the influence of hydrothermal method on chemical states of elements, MMC-W nanocomposites and pure MnCo2O4.5 were investigated by XPS measurements.

    • Facile fabrication of well-dispersed Cu<inf>x</inf>O nanoneedle on porous carbonized nano sponge and its promising application in the thermal decomposition of ammonium perchlorate

      2021, Powder Technology
      Citation Excerpt :

      As shown in Fig. 8, a possible mechanism was proposed based on proton transfer theory and electron transfer theory. On the one hand, based on the proton transfer theory, the LTD of AP begins with the transfer of proton from NH4+ to ClO4−, which is to form NH3 and HClO4 [42–44]. Afterwards, HClO4 gradually decomposes and reacts with NH3.

    View all citing articles on Scopus
    View full text