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In this study, the characteristics of diesel engines were tested with in-house produced mahua biodiesel blended with diesel and copper oxide nanoparticles (CuO NP) catalyst. The preliminary investigation used mahua biodiesel-diesel blends (M10, M20, and M30) among them M20 outperformed. Further M20 and CuO NP with concentrations of 25, 50, and 75 ppm are studied. Finally, the response surface methodology (RSM) was used to determine the appropriate NP concentration for M20. The findings showed that the blend of M20 with 60 ppm NP at 80% load had the highest desirability (0.9740), and the developed RSM model predicted engine responses with a mean absolute percentage error (MAPE) of 3.0962% to the confirmation test confirming the model’s accuracy. The optimized M20NP60 blend demonstrated superior combustion, performance and emission characteristics.

Volatile organic compounds (VOCs) emitted from industrial processes have high stability, low activity, and toxicity which cause continuous harm to human health and the atmospheric environment. Catalytic combustion has the advantages of low energy consumption and low cost and is expected to be one of the most effective methods to remove VOCs. At present, the selection of low cost, high activity, and durability catalysts are still a difficult problem. Industrial emissions of VOCs contain a certain amount of aromatic hydrocarbons; these substances are highly toxic substances, and, once inhaled by the human body, will cause serious harm to health. In this paper, the principle, advantages, and disadvantages of VOCs processing technology are analyzed in detail, and the catalytic combustion of aromatic hydrocarbons in VOCs is reviewed, including catalyst, reaction conditions, catalyst selection, inactivation reasons, and structure use. In addition, the deactivation effects of chlorine and sulfur on catalysts during the catalytic combustion of VOCs are discussed in detail. Finally, on the basis of literature research, the prospect of catalytic combustion of VOCs is presented, which provides influential information for further research on VOCs processing technology.

The thermal decomposition characteristic of ammonium perchlorate (AP) represents a critical factor in determining the performance of solid propellants, which has aroused significant interest on the structure and performance improvement of kinds of catalysts. In this study, bimetallic metal-organic frameworks (MOFs), such as CuCo-BTC (BTC = 1,3,5-Benzenetricarboxylic acid, H3BTC), CuNi-BTC, and CoNi-BTC, were synthesized by solvothermal (ST) and spray-drying (SD) methods, and then calcined at 400 °C for 2 h to form metal oxides. The catalysts as well as their catalytic effects for AP decomposition were characterized by FTIR, XRD, SEM, XPS, TG, DSC, TG-IR, EIS, CV, and LSV. It was found that the rapid coordination of metal ions with ligands during spray drying may lead to catalytic structural defects, promoting the exposure of reactive active sites and increasing the catalytic active region. The results showed that the addition of 2 wt% binary transition metal oxides (BTMOs) as catalysts significantly reduced the high-temperature decomposition (HTD) temperature of AP and enhanced its heat release. Of particular significance is the observation that SD-CoNiOx, prepared by spray-drying, reduced the decomposition temperature of AP from 413.26 °C (pure AP) to 306 °C and enhanced the heat release from 256.79 J/g (pure AP) to 1496.82 J/g, while concomitantly reducing the activation energy by 42%. By analysing the gaseous products during the decomposition of AP+SD-CoNiOx and AP+ST-CoNiOx, it was found that SD-CoNiOx could significantly increase the content of high-valent nitrogen oxides during the AP decomposition reaction, which indicates that the BTMOs prepared by spray-drying in the reaction system are more conducive to accelerating the electron transfer in the thermal decomposition process of AP, and can provide a high concentration of reactive oxygen species that oxidize AP to high-valent nitrogen oxide-containing compounds. The present study shows that the structure selectivity of the spray-drying technique influences surfactant molecular arrangement on catalyst surfaces, resulting in their ability to promote higher electron transfer during the catalytic process. Therefore, BTMOs prepared by spray drying method have higher potential for application.

Combustion catalyst is a key modifier for the performance of composite solid propellant. To exploit high-efficiency combustion catalyst, a fascinating bimetallic metal-organic framework [MnCo(EIM)2(DCA)2]n (1) was constructed by an active dicyandiamide (DCA) linker, Mn2+, Co2+ centers, and an 1-ethylimidazole (EIM) ligand. 1 possesses good thermal stability (Tp = 205 °C), high energy density (Eg = 24.34 kJ/g, Ev = 35.93 kJ/cm3), and insensitivity to impact and frictional stimulus. The catalytic effects of 1 contrasted to monometallic coordination compounds Mn(EIM)4(DCA)2 (2) and Co(EIM)4(DCA)2 (3) on the thermal decomposition of AP/RDX composite were investigated by a DSC method. The decomposition peak temperatures of AP and RDX of the composite decreased to 335.8 °C and 206.4 °C, respectively, and the corresponding activation energy decreased by 27.3% and 43.6%, respectively, which are better than the performances of monometallic complexes 2 and 3. The gas products in the whole thermal decomposition stage of the sample were measured by TG-MS and TG-IR, and the catalytic mechanism of 1 to AP/RDX was further analyzed. This work reveal potential application of bimetallic MOFs in the composite solid propellants. [Display omitted] •The second metal and highly active anion DCA were introduced into the combustion catalyst.•DCA assembles energetic ligands and metal centers to prepare novel energetic MOF.•MOF can greatly reduce the decomposition temperature and activation energy of AP and RDX at the same time.•The action mechanism of MOF on AP and RDX was revealed.

A novel design of micro-aluminum (μAl) powder coated with bi-/tri-component alloy layer, such as: Ni–P and Ni–P–Cu (namely, Al@Ni–P, Al@Ni–P–Cu, respectively), as combustion catalysts, were introduced to release its huge energy inside Al-core and promote rapid pyrolysis of ammonium perchlorate (AP) at a lower temperature in aluminized propellants. The microstructure of Al@Ni–P–Cu demonstrates that a three-layer Ni–P–Cu shell, with the thickness of ∼100 nm, is uniformly supported by μAl carrier (fuel unit), which has an amorphous surface with a thickness of ∼2.3 nm (catalytic unit). The peak temperature of AP with the addition of Al@Ni–P–Cu (3.5%) could significantly drop to 316.2 °C at high-temperature thermal decomposition, reduced by 124.3 °C, in comparison to that of pure AP with 440.5 °C. It illustrated that the introduction of Al@Ni–P–Cu could weaken or even eliminate the obstacle of AP pyrolysis due to its reduction of activation energy with 118.28 kJ/mol. The laser ignition results showed that the ignition delay time of Al@Ni–P–Cu/AP mixture with 78 ms in air is shorter than that of Al@Ni–P/AP (118 ms), decreased by 33.90%. Those astonishing breakthroughs were attributed to the synergistic effects of adequate active sites on amorphous surface and oxidation exothermic reactions (7597.7 J/g) of Al@Ni–P–Cu, resulting in accelerated mass and/or heat transfer rate to catalyze AP pyrolysis and combustion. Moreover, it is believed to provide an alternative Al-based combustion catalyst for propellant designer, to promote the development the propellants toward a higher energy.

The ammonium perchlorate (AP) plays a key role in the production of highly energetic materials for application in aerospace propulsion; and the development of catalysts for the production of high burning rate (BR) propellants based on AP is an active field of research. Recently, the graphitic carbon nitrides have been used as a metal-free catalyst for the AP thermal decomposition. Following this line of C=N conjugated polymeric systems used as modifiers, herein, the thermal behavior and decomposition mechanism of AP in the presence of hydrogen cyanide (HCN)-based polymers are described. These novel functional materials can be synthesized from the HCN tetramer, diaminomaleonitrile (DAMN) by a very simple one-pot thermal bulk polymerization. In the present work, the morphological characterization of these DAMN polymeric products and their effect in the thermal decomposition of AP was performed by differential scanning calorimetry (DSC). They were shown to exhibit catalytic activity for the thermal decomposition of this relevant oxidizer. Thus, adding 10% by mass of these nitrogen-containing conjugated polymers to AP decreases both the maximum exothermic peak temperature of decomposition and activation energy ( E a ). In addition, thermogravimetry–mass spectrometry (TG–MS) analysis has allowed to evaluate the effect of these innovative activators on the AP thermal decomposition mechanism. Evolved gas analysis seems to indicate that nitrogenous species, such as N 2 and N 2 O, are increased in the presence of these two-dimensional (2-D) macromolecular combustion additives. As a result, the DAMN polymers show a notable potential as a new kind of activators for the development of more efficient AP-based composite propellants.

To enhance the catalytic activity of copper ferrite (CuFe2O4) nanoparticle and promote its application as combustion catalyst, a low-cost silicon dioxide (SiO2) carrier was employed to construct a novel CuFe2O4/SiO2 binary composites via solvothermal method. The phase structure, morphology and catalytic activity of CuFe2O4/SiO2 composites were studied firstly, and thermal decomposition, combustion and safety performance of ammonium perchlorate (AP) and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) with it affecting were then systematically analyzed. The results show that CuFe2O4/SiO2 composite can remarkably either advance the decomposition peak temperature of AP and RDX, or reduce the apparent activation energy at their main decomposition zone. Moreover, the flame propagation rate of RDX was promoted by about 2.73 times with SiO2 content of 3 wt%, and safety property of energetic component was also improved greatly, in which depressing the electrostatic discharge sensitivity of pure RDX by about 1.89 times. In addition, the effective range of SiO2 carrier content in the binary catalyst is found to be 3 to 5 wt%. Therefore, SiO2 opens a new insight on the design of combustion catalyst carrier and will promote the application of CuFe2O4 catalyst in solid propellant.

Cu–Mn mixed oxides are well known as active combustion catalysts. The common method for their synthesis is based on co-precipitation, with NaOH as a precipitant, and is burdened with the possibility of introducing undesired Na contamination. This work describes the use of two organic bases, tetrabutylammonium hydroxide and choline hydroxide, as precipitating agents in a novel alkali-free route for Cu–Mn–Al catalyst synthesis. To obtain fine crystalline precursors, which are considered advantageous for the preparation of active catalysts, co-precipitation was carried out in the presence of starch gel. Reference materials prepared with NaOH in the absence of starch were also obtained. Mixed oxides were produced by calcination at 450 °C. The precursors contained MnCO3 doped with Cu and Al, and an admixture of amorphous phases. Those prepared in the presence of starch were less crystalline and retained biopolymer residues. The combustion of these residues during calcination enhanced the formation of larger amounts of the Cu1.5Mn1.5O4 spinel phase, with better crystallinity in comparison to catalysts prepared from conventionally synthesized precursors. Tests of toluene combustion demonstrated that the catalysts prepared with starch performed better than those obtained in starch-free syntheses, and that the mixed oxides obtained by the alkali-free route were more active than catalysts prepared with NaOH. Catalytic data are discussed in terms of property–performance relationships.

Combustible gas leakage monitors (CGLMs) are widely used to detect gas leaks in factory buildings, catering, and gas pipelines. They are often exposed to various complex environments, particularly extreme temperature environments, which will lead to component failure, poor measurement accuracy, or even loss of function. However, there is still lacking of a systematic method to evaluate the environmental adaptability of CGLMs under extreme high- and low-temperature environments. In this paper, a comprehensive and innovative method to quantitatively estimate the environmental adaptability of CGLMs under extreme temperature environments through combining function, integrity, and safeguard capability parameters obtained from different measurements was proposed. The measurement performances and battery performance of laser methane sensor (LMS) and catalyst combustion methane sensor (CCMS) were investigated. It is revealed that the high-temperature condition even 75 °C has small effect on the measurement accuracy of the LMS and CCMS, and the measurement accuracy reduces about 6.67%, while the low-temperature condition has an obvious effect on the measurement performance of CCMS. The measurement accuracy of CCMS drops by 50% at − 35 °C. Based on the analytic hierarchy process, a comprehensive evaluation model has been developed to effectively evaluate the environmental adaptability of LMS and CCMS. The work provides engineering guidance for the application of CGLMs in an extreme environment.