Perovskite-type catalysts were widely used in the field of automobile exhaust purification due to their inherent physicochemical properties and excellent doping characteristics. A series of La1-xMxCo1-yNyO3 (M=Ce, Ca; N=Fe, Mn) perovskite-type catalyst samples were prepared by sol-gel method for the four-way purification of PM, NOx, CO, and HC emitted by diesel exhaust. The activity of catalyst samples was tested by simulation experiments and hydrogen temperature-programmed reduction (H2-TPR). Catalyst samples were characterized by means of XRD, FT-IR, SEM, BET, and XPS analysis. The results demonstrated that the perovskite-type catalyst samples with a particle pore size of 3–5 μm can be prepared by sol-gel method. When A-site of LaCoO3 perovskite-type oxide was doped by cerium ions, the catalyst samples produced small distortion. The doping of cerium ions to A-site was more conducive to the four-way purification of diesel exhaust than calcium ions. La0.8Ce0.2CoO3 perovskite-type samples showed the best purification efficiency, and the purification efficiencies of PM, NOx, CO, and HC were 90%, 85%, 94%, and 100%, respectively. When the B-site of La0.8Ce0.2CoO3 perovskite was doped with iron ions, the purification efficiency of catalyst samples for PM and NOx can be further enhanced. When the B-site of La0.8Ce0.2CoO3 perovskite was doped with manganese ions, the purification efficiency of the catalyst samples for PM can be further enhanced. It can be seen from the simulation experiments that La0.8Ce0.2Co0.7Fe0.3O3 perovskite was the best doping amount, and the purification efficiencies of PM, NOx, CO, and HC were 95%, 92%, 94%, and 100%, respectively.

No abstract

In this paper, LaCoO3 porous perovskite was synthesized using wood powder template combined with sol-gel process, while LaCoO3 prepared by traditional sol-gel method was used as a comparison. The catalysts prepared by different methods were characterized by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), N2 adsorption-desorption, and the particulate matter (PM) trapping and catalytic oxidation tests were carried out by engine bench test and thermogravimetric analyzer (TGA). The results showed that the porous LaCoO3 successfully replicated the structural features of wood powder from macroscopic to tracheid, forming a porous structure. Porous LaCoO3 exhibits better catalytic activity than powdered LaCoO3 with similar specific surface area, this can be attributed to the porous structure of LaCoO3, which increases the contact area and the number of contact points between PM and catalyst.

Biomorphic porous La0.8Ce0.2Fe0.3Co0.7O3 perovskite‐type catalysts are synthesized through a facile bio‐templating method taking wood fiber as template for achieving the four‐way purification of PM, NOx, CO, and HC emitted by automobile exhausts. The catalyst samples were characterized by X‐ray diffractometer, Fourier‐transform infrared spectroscopy, scanning electron microscope and Brunauer–Emmett–Teller analysis. The results showed that catalyst sample calcined at 700°C obtained high purity, high surface area (4.01 m2/g), wide pore size distribution and retained the initial wood fiber structure, which was suitable for purifying automobile exhausts. In addition, the performances for four‐way purification under the simulated exhaust were analyzed by simulation test bench. The highest purification efficiency of PM, NOx, HC, and CO can reach 92%, 92%, 98%, and 76%, separately. Moreover, four‐way purification mechanism was deduced according to the theoretical research of Mars‐van krevelen on the redox reaction mechanism and experimental result.