Diesel Particulate Filters (DPFs), motivated by more and more stringent emissions regulations, have been widely used as the only economically and technically feasible means to meet the current and future Particulate Matter (PM) emissions limits.
Improving the Performance of Catalyzed Diesel Particulate Filter
The development of a safe, fast and cost-effective Diesel Particulate Filter (DPF) regeneration procedure is the main technological challenge in the use of this system. In the previous studies, it was shown that the simultaneous use of a specific catalyst loaded DPF and a microwave applicator, with 15%wt of CuFe2O4, enables the reduction of the energy, temperature and time needed for the DPF regeneration.
Starting from these promising results, the research is focused on additional enhancement of the performances of the catalyzed DPF with regard to catalytic activity, with the aim to reduce the microwave energy and the temperature needed for the regeneration. Therefore, the objectives of the research are to perfect the preparation procedure of the catalytic DPF, to explore the effect of the active species load and to confirm the feasibility of the microwave technology by evaluating the energy balance of the regeneration phase, and comparing it to the truly employed regeneration technologies.
Hiden Analytical System
In this study, hydrogen is one of the important characterization tests carried out on the prepared catalysts – Temperature Programmed Reduction (H2-TPR): these measurements are preformed using SiC catalytic monolith in a room temperature of 900 °C at a heating rate of 5 °C/minute in 5% H2/N2 flow. The reaction parameters (concentrations and temperature) are tracked using a customized Hiden Analytical system based on HPR-20 QIC R&D & Proteus Multi-stream Sampling Valve configuration, capable of sampling up to 20 discrete gas streams, which were subsequently analyzed using a mass spectrometer (Figure 1).
Figure 1. The Hiden Analytical System in the Lab
As an example, Figure 2 displays the result of a H2-TPR carried out using a SiC monolith loaded with 15%wt of CuFe2O4.
Figure 2. H2-TPR profile of a SiC monolith loaded with 15%wt of CuFe2O4
The H2-TPR profile reveals two pronounced reduction peaks that were observed at about 300 °C and 610 °C. The peaks are due to the reduction of CuFe2O4 to Cu and Fe3O4, and then of Fe3O4 to Fe. The two reactions are:
|3CuFe2O4 + 4H2 → 3Cu + 2Fe3O4 + 4H2O
|Fe3O4 + 4H2 → 3Fe + 4H2O
The total amount of H2 consumed per mole of Cu (H2/Cu ratio) was 4.4, which is found to be consistent with that of the full reduction of CuFe2O4 to Cu and Fe according to the following reaction:
|CuFe2O4 + 4H2 → Cu + 2Fe + 4H2O
The value of 4.4 relates to approximately 17%wt of CuFe2O4 which is consistent with the estimated 15%wt of CuFe2O4 on the monolith. Moreover, after the reduction, the Cu and Fe mixture is beneficial for the formation of CuFe2O4 at high temperature (about 800 °C in air), as reported in the literature. The TPR profile reveals that the catalyst-loaded monolith can act as a redox oxidation catalyst active in a temperature ranging from 300 °C to 800 °C due to the presence of good and homogeneous copper ferrite dispersion.
Project Summary by:
V. Palma & E. Meloni
University of Salerno, Department of Industrial Engineering
Via Ponte don Melillo, 84084 Fisciano (SA)
Paper Reference: V. Palma, P. Ciambelli, E. Meloni & A. Sin (2013) “Study of the catalyst load for a microwave susceptible catalytic DPF” Catalysis Today, 216, 185-193
This information has been sourced, reviewed and adapted from materials provided by Hiden Analytical.
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