The Modification Of Cordierite Supports And Its Effect On The Monolith Ru/cordierite Catalyst For Ammonia Synthesis

The effects of the three treatment methods for cordierite support, such as acid treatment, rare earth modification and the purification of carbon nanotubes, on the activity of catalyst were studied. We prepared Ru/cordierite catalysts with RuCl3, studied the activity for ammonia synethsis and discussed the effect of the concentration of ruthenium, barium, potassium and the rare earth on the activity of the Ru/cordierite catalyst.The results indicate that (1) the acid treatment increases the BET surface area, pore volume, and the meso-, micropores. The composition of the cordierite has also been changed after the acid treatment, which increases the acidity of the support. The activity of the ruthenium catalyst with acid treatment support is lower than that with untreated support.(2) La₂O₃,Pr₂O-3,Nd2O3 and Sm₂O₃ can improve the activity of Ru/cordierite catalyst, but the effect is unconspicuous. CeO2 can effectively increase the activity of Ru/cordierite catalyst which maybe result for the high specific surface area, suitable pore volume and a high dispersion of Ru caused by the morphology effect for CeO2.(3) The carbon nanotubes coated cordierite (CNTs-cordierite) was fabricated by pyrolysis of ethine on cordierite with iron catalyst. A significantly increase in the BET surface area, pore volume was observed and suitable pore-size distribution was obtained after methanation and nitric acid oxidation treatment. Function groups were also introduced by nitric acid oxidation treatment. All these improve the activity of Ru/CNT-cordierite catalyst and decrease the reaction temperature of the highest activity.(4) Both barium and potassium are effective promoters for Ru/cordierite catalyst, and have an optimal concentration. But the tendency of the activity for...