**3. Results**

*Global Warming and Climate Change*

abilities of the catalysts [12].

**2.2 Catalyst preparation**

≥99.9% purity) were obtained from Alfa Aesar.

**2. Methodology**

**2.1 Materials**

Thus, the catalyst is required to increase the rate and decrease the time of the process. Various catalysts are proposed, and perovskites are discussed in detail. Because oxidation and reduction reactions must co-occur, perovskites are efficient owing to their high redox properties and high oxygen storage capacity (OSC) in some perovskites. In this work, we prepared a series of LaFe1-xCuxO3 perovskitetype nanopowder by sol–gel auto-combustion technique following calcination under the same experimental conditions. The metal nitrates and EDTA along with citric acid were dissolved in water, the homogeneous mixtures then added with ammonia to balance pH and kept to form a gel, and later combusted and calcined in the air at last. The as-prepared samples were characterized by XRD, FE-SEM, BET, particle size, TGA/DTA, and carbon dioxide analysis techniques to investigate the effect of the introduction amount of Cu2+ on the morphology, structure and redox

Lanthanum nitrate hexa-hydrate (La(NO3)3·6H2O, ≥99.9% purity), copper nitrate (Cu(No3)2, ≥99.9% purity), and iron nitrate nonahydrate (Fe(NO3)3·9H2O,

All catalyst powders were prepared using the EDTA-citrate auto combustion method [5]. Metal nitrates were employed as desired metal pre-cursors for support. A 2 g-scale preparation for LaFe1-xCuxO3-Δ is described below as an example. Lanthanum nitrate (La(NO3)3·6H2O) was dissolved in deionized water (100 mL), followed by mixing into an aqueous solution of copper and iron nitrates in stoichiometric ratios at room temperature. EDTA (3.8 g) dissolved in an aqueous NH3 solution was then dropped into the mixed solution, followed by the addition of solid citric acid (3.7 g) upon stirring. Molar ratio of total metal ions (La + Fe-Cu), EDTA, and citrate is 1.0:1.0:1.5, respectively. NH4OH was used to adjust the pH of the solution to the desired value of 11 [12–14]. The solution was then heated above 80°C slowly and became dark brown after being brown-orange at the beginning.

**82**

**Figure 3.**

*XRD plot of LaFeO3 doped with copper on B site.*

As shown in **Figure 4**, doping of copper of the perovskite did not affect the crystal structures of LaFe1-xCuxO3 samples (LFCO-10–LFCO-20). The peaks were in negligible deviation to the peaks of LFO. The characteristic diffraction peaks were at 22.6°, 32.2°, 38.0°, 39.6°, 46.3°, 53.3°, 57.4°, 67.4°, and 76.7° in the diffraction data of all samples can be correlated to the indices of the crystal planes of (101), (121), (112), (220), (141), (311), (240), (242), and (204), signifying that the fabricated samples were finely crystallized with three-dimensional orthorhombic structure (JCPDS No. 37-1493) [15, 16]. **Figure 4** zooms in the XRD graph of LFCO-10 and contrasts it with the pure LFO synthesized in-situ and in agreement with the JCPDS data.

**Table 1** shown below depicts the a, b, c values for lattice constants of the perovskite LaFeO3 and [17] LaFe1-xCuxO3. The introduction of Cu(II) with a larger ionic radius (0.730 Å) to replace Fe(III) with smaller ionic radius (0.645 Å) did not result in the expansion of LFO unit-cell [18, 19]. The smaller cell volume of LaFe1-xCuxO3 might be caused by the defects in the form of anionic vacancies, which maintained the electroneutrality in LaFe1-xCuxO3 [17, 20–26]. In **Table 1**, the crystallite sizes of Cu-doped LFO samples were smaller than that of undoped sample and decreased with increasing amount of Cu dopant.

This concurs with the literature, it shows that increasing Cu doping could cause lattice distortion and hinders the growth of large crystallites in the samples. The large degree of crystallinity with minute defects fosters the reduction in the recombination of electron–hole pairs, leading to enhanced efficiency of the soot oxidation reaction [15].

**Figure 4.** *Zoomed in image of XRD LFCO-10.*


### **Table 1.**

*Lattice parameter and cell volume calculations inferred from XRD analysis.*


### **Table 2.**

*Calculations obtained from BET analysis about structural properties.*

The information can be observed from **Table 2**, the prepared samples exhibited similar morphology, relating to the pore size consisting of nano and spherical particles. That the Cu-doping did not significantly affect the morphology and particle size of sample. The decrease in the pore size signifies that the Cu ions have been inserted into the lattice. On the other hand the XRD shoes no distortion into the lattice, which in turn explains the possible structural acceptance capability of the LFO towards favorable Cu doping.

TGA analysis results shown below proves that the catalyst is acting on the soot to reduce the carbon black particles in the controlled environment (here fixed air velocity was used) (**Figure 5**).

**85**

**Figure 6.**

*Reducing Green House Effect Caused by Soot via Oxidation Using Modified LaFe1-xCuxO3…*

The focus of the research is to dissect the problem of global warming by understanding scope doping of copper on the LFO structure, then to analyze the effect on the properties of the LFO and correlate them with the performance characteristics of the catalyst with the reaction of soot oxidation. Following the results, we are attempting to circumnavigate the altered properties of LFCO to the catalytical

Firstly, no crystalline Cu peaks were observed and the congruent, perovskite phase formed in all cases (LFO-10Cu–LFO-30Cu). However, the amount of Cu doping in the inverse proportion with the intensity of diffraction peaks because it

> *Cell volume can be calculated for orthorhombic structure as V = abc. For the LFCO-10- (since a = c), V = (5.554^2)\*7.845 A°m^3 = 242.16 A°m^3 and so on Which gives the below inverse relation*

The cell volume of LaFe1-xCuxO3 is marginally smaller than that of LFO; this

We can observe the trend in the BET analysis when synthesized at maximum Cu doping concentration; the particles may have fused to form large convolutions, This may also explain the more significant pore volumes and sizes for the samples of LFO-10Cu and LFO-20Cu when compared with others [8]. Increasing pore volume is the indication of more room for oxygen ions to combine with carbon, following reaction will spread light on the intricacies of the steps involved. Now as we see in the culmination of discussion, we are relating how the catalyst could have acted on the UHC (soot) and where rate-limiting step where the most unstable species carbon trioxide is formed and exactly in that step the LFO-Cu will facilitate the conversion in the diesel particulate filter (DPF) It will lower the temperature required for reaction to attain 50% conversion. From the TGA, we could infer the temperature to be around 350°C which is significantly lower than 600°C observed

The chemical aspects of soot oxidation as discussed earlier indicated a need for catalyst. Here we can infer from TGA data that indeed the 50% conversion temperature of the catalyzed reaction is near to the exhaust temperature of the diesel engine, which in turn follows the possibility of soot oxidation reaction in the DPFs. Once installed the catalyst will reduce the amount of soot exiting the exhaust. The decrease in soot

*DOI: http://dx.doi.org/10.5772/intechopen.90460*

value decreased with increasing Cu doping.

in reality and 500°C observed in the 0.

The controlled environment of the TGA equipment.

*Possible reaction mechanism and role of catalyst—soot oxidation.*

**4. Discussion**

performance.

was broadening them.

*Reducing Green House Effect Caused by Soot via Oxidation Using Modified LaFe1-xCuxO3… DOI: http://dx.doi.org/10.5772/intechopen.90460*
