Preparation-Properties Relation of Mn-Cu Hopcalite Catalyst
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Copyright: © 2020 Ardita Mele, Ilo Mele and Altin Mele. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Problem statement: The Mn-Cu hopcalite catalyst was used for the conversion of CO to CO2 at low temperatures. It was the catalyst of choice in the gas masks for respiratory protection in mines, aircrafts, military, spatial laboratories. Approach: The efficiency of hopcalite catalyst depends on its surface parameters. Its surface characteristics can be influenced from the chosen way of the MnO2 and CuO precipitation and from the pressure of pelletizing. Results: The hopcalite samples has been prepared by precipitation of MnO2 and by adding CuSO4 further in the solution the adsorption of Cu2+ ions on MnO2 particles surface is achieved. After acidification of the solution up to pH = 3 the copper is precipitated in form of Cu (OH)2CuCO3 by adding NaHCO3. Precipitate was washed, dried, pressed, crushed, sieved (1-2 mm) and calcined at 180°C for 3 h. MnO2 and hopcalite samples were characterized by XRD. The activity was evaluated by determination of its protection time and it was 610 min, better than activity of a commercial catalyst. Specific surface area, pore volume and density were measured by nitrogen adsorption and mercury intrusion porosimetry. The X-Ray diffractograms shows that the only crystallinity of hopcalite comes from MnO2, which is present mainly in amorphous form. By increasing the pressure in the pelletizing step, a significant decrease in the specific surface area (247.64-147.77 m2 g-1) and in the total pore volume (446-278 mm3 g-1) is observed in the hopcalite samples. Conclusion: The obtained hopcalite catalyst by the two step precipitation method shows high catalytic activity. The increasing pressure increases the strength and reduces the specific surface area and pore volume. A pressure of 500 kg cm-2 is recommended for the hopcalite production procedure.
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- pelletizing pressure
- protection time