Suitability of pyrolusite as additive to activated coke for low‐temperature NO removal

Abstract

BACKGROUND Pyrolusite was used as additive to prepare coal‐based activated coke (AC) for low‐temperature NO removal. The pyrolusite modified AC was prepared by a blending method, and the denitrification performance was evaluated in a lab‐scale simulated fixed‐bed reactor. RESULTS The blending of pyrolusite promoted the specific surface area and pore structure of AC, even though the MnO2 and Fe2O3 showed inhibitory effects when blended separately. Both the basic and acid sites of AC‐Mn(x) increased owing to the participation of the blended MnO2 during the activation, while the blending of Fe2O3 showed an inhibited effect. AC‐P10 showed the highest NO removal efficiency at 74.2%, which was 32.8%, 27.0% and 24.2% higher than that of AC, AC‐Mn4 and AC‐Fe6. The operating temperature adaptability and stability of catalysis activity of AC‐P10 are good. Manganese is the main catalyst of AC‐P(x), and Fe is an accelerant to stimulate the catalytic activity of Mn. The extremely high NO removal activity of AC‐P(x) was due to the synergistic effect of surface functional groups and metals, but the catalysis of metals played a more important role. CONCLUSION Pyrolusite is suitable to prepare the AC‐based denitrification catalyst (AC‐P(x)) for SCR NO removal because the Mn and Fe contained in the pyrolusite showed a synergistic effect. © 2017 Society of Chemical Industry

Co-blending modification of activated coke using pyrolusite and titanium ore for low-temperature NOx removal

“…To simplify the preparation and reduce costs, the blending method that integrates AC preparation and catalyzation modification in one step extend the applicability of the catalyst precursor to catch great attention in the past few years. Jiang had prepared the metal oxide-blended activated carbon from walnut shells for flue gas desulfurization 18 , as well as the coal-based AC 13,19 , and the recent work observed clear improvement of SCR activity of the blending-modified AC 20 . However, studies on the SCR application of the blending-modified AC is still in its infancy.…”

Enhancement of the denitrification efficiency over low‐rank activated coke by doping with transition metal oxides

“…At the same time, nitrogen‐containing groups (pyridine and pyrrole) on the AC surface as a catalyst can promote the selective catalytic reduction (SCR) of NO with NH 3 . However, compared with commercial V 2 O 5 /TiO 2 catalysts with a denitrification efficiency above 90%, activated coke still needs further improvement, as the denitrification efficiency is currently only 40% to 70% …”

“…A variety of modification methods are used to improve the denitrification performance of AC . The simplest and most commonly used method is to treat AC with nitric acid . After reacting with nitric acid, oxygen‐containing and nitrogen‐containing groups on the AC surface significantly increase.…”

“…The metal oxides loaded on AC can also improve denitrification activity significantly. The oxides of transition metals, such as V, Mn, Fe, Cr, and Ni, impregnated on AC can efficiently promote the removal of NO . The transition metal oxides can highly disperse onto an inert carrier to remove NO as active components and play a dominant role in NO oxidation .…”

The study on continuous denitrification, desulfurization of pyrolusite/activated coke hybrid catalyst

“…6,16 Natural minerals, rich in transition metals, showed great prospect due to its relatively low cost and the simple preparation procedure when it used as precursor, 17 and the catalytic activity and stability of some kinds of natural minerals for SO 2 and NO removal also have been proved. 18,19 However, it is noteworthy that the formation of metal sulphates during the desulfurization process on the surface of modied AC is unavoidable for almost all the transition metals, and they are difficult to be decomposed under commonly used regeneration temperatures (#500 C). 20 In our previous research, we had discussed the effects of MnSO 4 on SO 2 removal over MnO 2 modied AC by lending method (i.e.…”