The effects of different mixtures of organic structure-directing agents (OSDAs) on the formation of SAPO-34 structure have been investigated. Different OSDAs, namely, triethylamine (TEA), tetraethylammonium hydroxide (TEAOH), and morpholine (Mor) and their combinations were used to synthesize SAPO-34 by a hydrothermal method. The template concentration was optimized by eliminating the competing phases to obtain the purest form of SAPO-34 phase. The as-synthesized samples were analyzed by XRD, FE-SEM/EDS, FT-IR, surface area/pore volume measurements, NH3-TPD, TG/DTA, and 29Si NMR MAS. The selection of template notably impacts the crystal size and physicochemical characteristics of as-synthesized SAPO-34. The sample prepared with 3 Mor : 3 TEA : 1 TEAOH exhibited the highest total acidity, smallest crystal size below 3 µm, and high surface area up to 697 m²/g.

SAPO-34 was prepared with a mixture of three templates containing triethylamine, tetraethylammonium hydroxide, and morpholine, which leads to unique properties for support and production cost reduction. Meanwhile, Cu/SAPO-34, Fe/SAPO-34, and Cu-Fe/SAPO-34 were prepared through the ion-exchanged method in aqueous solution and used for selective catalytic reduction (SCR) of NO_x with NH₃. The physical structure and original crystal of SAPO-34 are maintained in the catalysts. Cu-Fe/SAPO-34 catalysts exhibit high NO_x conversion in a broad temperature window, even in the presence of H₂O. The physicochemical properties of synthesized samples were further characterized by various methods, including XRD, FE-SEM, EDS, N₂ adsorption-desorption isotherms, UV-Vis-DRS spectroscopy, NH₃-TPD, H₂-TPR, and EPR. The best catalyst, 3Cu-1Fe/SAPO-34 exhibited high NO_x conversion (> 90%) in a wide temperature window of 250–600 °C, even in the presence of H₂O. In comparison with mono-metallic samples, the 3Cu-1Fe/SAPO-34 catalyst had more isolated Cu²⁺ ions and additional oligomeric Fe³⁺ active sites, which mainly contributed to the higher capacity of NH₃ and NO_x adsorption by the enhancement of the number of acid sites as well as its greater reducibility. Therefore, this synergistic effect between iron and copper in the 3Cu-1Fe/SAPO-34 catalyst prompted higher catalytic performance in more extensive temperature as well as hydrothermal stability after iron incorporation.

A series of Cu/ZSM-5, Fe/ZSM-5, and Cu-Fe/ZSM-5 catalysts (Si/Al in ZSM-5=25) were prepared by different metal loadings using the liquid ion-exchange method. Several characterization methods were conducted to explore the effects of metals on the physical and chemical properties of catalysts. Meanwhile, the electron paramagnetic resonance method is also used to assess the copper and/or iron elements coordination and valence state at intersections or in channels of ZSM-5. The metal-loading effects of all catalysts on the catalytic activities were studied for the removal of NO_x in a fixed-bed flow reactor using selective catalytic reduction with ammonia (NH₃-SCR). The results showed that the irons addition could markedly broaden the operation temperature range of the Cu/ZSM-5 catalyst for NH₃-SCR between 200 and 550°C due to the presence of more isolated Cu²⁺ ions as well as additional oligomeric Fe³⁺ active sites and Fe_xO_y oligomeric species. This paper gives a facile and straightforward way to synthesize the practical-promising catalyst applied in NH₃-SCR technology to control NO_x emissions.

During the course of this inquiry, an attempt has been made to understand the thermal decomposition characteristics and burning rate of ammonium perchlorate working as an oxidizer and polyvinyl chloride functioning as a fuel binder for high energy-carrying composite materials. The samples were examined for material morphology and elemental composition by scanning electron microscope and dispersive energy X-ray spectrometer methods. In addition, a NETZSCH simultaneous thermal analyzer comprising a differential scanning calorimeter and a thermogravimetric analyzer has also been utilized to ascertain the thermal decomposition method associated with each composition. The thermal decomposition process of the energy-carrying composite materials consisted of three distinct stages, and the mass loss rate during this process ranged from 100 °C to 500 °C, accounting for 99% of the sample mass. The enhanced catalytic activity of Fe2O3 in ECCMs significantly lowers the exothermic decomposition temperature and increases the total heat release. Besides, the burning rate studies have been conducted at ambient and different pressures with and without Fe2O3, providing valuable insights into the combustion behavior of ECCMs under varying conditions.