Synthesize of magnetite Mg-Fe mixed metal oxide nanocatalyst by urea-nitrate combustion method with optimal fuel ratio for reduction of emissions in diesel engines

In the present study, Mg0.25Fe2.75O4 nanocatalyst for reduction of emissions in diesel engine was fabricated via urea-nitrate combustion method. The effect of urea concentrations as fuel on its structural characteristics and Oxygen Storage Capacity (OSC) was thoroughly investigated. The results of various characterization analyses showed that fuel ratio significantly affects crystallinity, textural, size and morphology of particles, and thermal stability of nanocatalyst. These are mainly due to increase in combustion temperature and duration. The Mg0.25Fe2.75O4 fabricated at fuel ratio of 2.5 times of stoichiometric ratio exhibited the lowest weight loss/high crystallinity (less than 1 wt %) and lowest lattice parameter (8.346 Å) which are related to well diffusion of Mg cations into ferric oxide as host. The Raman and FTIR analyses showed the existence of strong peaks correspond to formation of tetrahedral and octahedral sublattices and also the formation of spinel structure of MgFe2O4. The reduction in crystalline size, obtained with higher amount of fuel, resulted in a higher surface area (23.6 m2/g), higher pore volume (0.0950 cc/g) and proper particle size distribution (25–35 nm). These cause a better catalytic activity. Moreover, the enhanced OSC (8661 μmol H2/g) along with shifting the reduction peaks to lower temperatures, as major attributes in relation to catalytic technologies, confirmed the strong effect of fuel ratio of 2.5 on fabrication process of Mg0.25Fe2.75O4. Finally, the highest reduction in HC (33%), CO (14-17%), PM1.0 (16%), and CO2 (12%) achieved, using the optimum sample-mixed diesel fuel at 90 ppm.</p

Influence of doping Mg cation in Fe3O4 lattice on its oxygen storage capacity to use as a catalyst for reducing emissions of a compression ignition engine

Improving oxygen storage capacity (OSC) of metal oxides by doping with metal cations can produce a catalyst with superior properties to improve engine performance and reduce emissions. In this study, Mg cations were incorporated into a ferric oxide lattice to form Mg0.25Fe2.75O4 via the solution combustion method. The structure, texture, morphology, and oxygen storage capacity of the samples were deeply investigated. The catalytic activity of Mg0.25Fe2.75O4 was finally compared with Fe3O4 as a reference nanocatalyst in terms of its combustion emissions using a six-cylinder Cummins diesel engine. It was found that the doped catalyst presented high crystallinity containing a mixture of the spinel-type crystal lattice and α-Fe2O3 structure, which confirms the ability of the solution combustion method for the fabrication of well-crystalline catalysts. The crystalline structure, surface area, and porosities and vacancy of spinel structure of Mg doped catalyst compared to the inverse spinel structure of Fe3O4 affect OSC of the samples, such that a significant increase in OSC of Fe3O4 (7941 µmol/g) occurred by loading of Mg cations (8661 µmol/g). Based on the engine emissions results, synthesized nanocatalysts are beneficial for decreasing the hydrocarbon (HC), carbon monoxide (CO), and particle mass (PM1.0) emissions. More specifically, the effect of nanocatalysts OSC would be dominated by the impact of increased soot oxidation, leading to PM1.0 reduction

Effects of enhanced fuel with Mg-doped Fe3O4 nanoparticles on combustion of a compression ignition engine:Influence of Mg cation concentration

The present study focuses on the synthesis of novel catalytic nanoparticles and their effect on combustion, performance, and emission characteristics of a diesel engine. For this purpose, Mg cations were doped into a Fe3O4 lattice to form MgxFe(3-x)O4 (x = 0.25, 0.5, 0.75, and 1) using a solution combustion method. Comprehensive characterization studies were carried out to assess the oxygen storage capacity (OSC) and the properties of final powders. These synthesized samples were dispersed in a diesel-biodiesel blend fuel with a concentration of 90 ppm. Assessment of the structure of the samples proved the formation of MgFe2O4 structures, suggesting that Mg cations were embedded into the Fe3O4 and formed appropriate structures. The OSC was reduced from 8661 μmol/g (Mg0·25Fe2·75O4) to 7069 μmol/g (MgFe2O4) by introducing additional Mg cations. When run on a six-cylinder diesel engine, the fuel mixed from the synthesized samples did not significantly influence the indicated power (IP), brake specific fuel consumption (BSFC) or the brake thermal efficiency (BTE). In addition to the obtained result for the OSC of the sample, which declined by increasing the Mg concentration in the Fe3O4 lattice, using the sample with the highest concentration of Mg cations, a considerable reduction was detected in the major exhaust emissions such as HC (56.5%), PM1 (35%), and PN (37%) and a slight decrease occurred in CO (7%) compared to the engine fueled by pure fuel. Based on the experimental engine results, the MgFe2O4 sample can be considered as a useful nanocatalyst for mixing in the fuels for emissions reduction.</p

Synthesis and evaluation of catalytic activity of NiFe2O4 nanoparticles in a diesel engine : An experimental investigation and Multi-Criteria Decision Making approach

Exposure to gaseous and particulate matter (PM) emissions from engine combustion can result in severe human health risks. Although blending biodiesel-diesel fuel presents reduction in diesel engine emissions, mixing fuel with an oxidation catalyst with considerable oxygen storage capacity (OSC) characteristic might better reduce the harmful engine emissions. In the present study, NiFe2O4 nanoparticles were synthesized via the combustion method. X-ray diffraction analysis, Raman spectroscopy and temperature programmed reduction techniques were used to assess the structure and OSC of the nanoparticles. The data was collected using a diesel engine in fuel blends of "B20–NiFe2O4" under steady state conditions, at 25, 50 and 75% of engine full load, and at a constant engine speed of 1500 rpm. The Analysis of variance (ANOVA) approach was used to interrupt the engine outputs. The soot samples emitted from diesel engine fuel containing B20–NiFe2O4 were collected for transmission electron microscopy analysis to determine their morphology and nanostructure. NiFe2O4 nanoparticles showed spinel structure with an OSC of 13580 μmol/g. There was a considerable reduction in exhausted particles with the B20–NiFe2O4 blend. The average emission reductions for hydrocarbons, carbon monoxide, particle number, and particle mass were 44.3%, 12%, 26%, and 30%, respectively. The soot particle internal structure showed that for the B20–NiFe2O4 blend, particles were structurally arranged around the outer region of the core. Finally, the Technique for Order Performance by Similarity to Ideal Solution (TOPSIS) was performed using the experimental data (all investigated parameters) to rank the alternatives. The optimization result reveals that B20–NiFe2O4 is a good alternative for different conditions of engine loading. By using the TOPSIS ranking, the engine can be operated in the most optimal manner at 50% load using B20–NiFe2O4.</p