To accurately evaluate the phase effects of MnO x in Mn-Ce catalysts towards to low temperature NO x removal performance with NH 3 , MnCO 3 @CeCO 3 OH was synthesized firstly and decomposed to MnO 2 @CeO 2 , Mn 2 O 3 @CeO 2 and Mn 3 O 4 @CeO 2 with similar size and morphology, this will avoid the influence of size and morphology on the experimental results. Experimental results show that the MnO 2 @CeO 2 exhibiting the best NO conversion ratio, which achieved nearly 96.5 % at a low temperature of 150 °C, and the catalytic performance order of MnO x @CeO 2 is determined as: MnO 2 @CeO 2 > Mn 2 O 3 @CeO 2 > Mn 3 O 4 @CeO 2 below 200 °C, and MnO 2 @CeO 2 > Mn 2 O 3 @CeO 2 ≈Mn 3 O 4 @CeO 2 at range of 200 –400 °C. But the N 2 selectivity of Mn 2 O 3 @CeO 2 reaches 96 % at 100 °C which was higher than that of MnO 2 @CeO 2 and Mn 3 O 4 @CeO 2 . Characterizations including BET, XRD, SEM, H 2 -TPR, NH 3 -TPD and FTIR show that MnO 2 @CeO 2 has maximum specific surface area, a stronger redox ability, and more surface acid sites.
Tao Zhang,Guiqing Zhang,Zuoying Cao,Mingyu Wang,Wenjuan Guan,Shengxi Wu,Qinggang Li
Background The NH 3 , a clean reductant, generated by the thermolysis of NH 4 VO 3 , is not effectively utilized in the conventional process of vanadium metallurgy. Additionally, the preparation process of V 2 O 3 is both long and costly. Ammonia recovery is essential to prevent environmental issues resulting from ammonia release. By direct thermolysis of NH 4 VO 3 and effectively utilizing of active NH 3 , it is possible to achieve the short flow and green process for the production of V 2 O 3 . Method In an open NH 3 atmosphere, one end of the flange was connected to the liquid ammonia gas cylinder, while the other end was connected to the tail gas absorber. Furthermore, in a closed NH 3 atmosphere, both ends of the tube furnace were sealed with flanges, and the initial atmosphere in the tube was pre-injection NH 3 . The products of NH 4 VO 3 thermolysis were characterized using various techniques, including XRD, FT-IR, ICP-OES, SEM, XPS, and TG. Significant finding The thermolysis process of NH 4 VO 3 with pre-injection of NH 3 under the sealed condition was a simulation of the continuous production process of V 2 O 3 using a rotary kiln in industrial production. The rational utilization of ammonia resulted in the reduce of energy consumption, extra reductant consumption, and significant NH 3 emissions compared to the traditional V 2 O 3 production process. It was observed that V 2 O 3 was easily obtained through the thermolysis of NH 4 VO 3 with pre-injection of NH 3 under the sealed condition at 600 °C for 3 h, using a dosage of NH 4 VO 3 ranging from 2 g to 10 g. During this process, the NH 4 VO 3 went through the phase transition as follows: NH 4 VO 3 →NH 4 V 3 O 8 →(NH 4 ) 0.38 V 2 O 5 →V 6 O 13 →VO 2 →V 4 O 7 →V 3 O 5 →V 2 O 3 , and the relevant characterization of products showed that the V 2 O 3 obtained was qualified. These experimental results were of great significance to the industrial practice of vanadium metallurgy. Based on these results, short flow and green process of V 2 O 3 could be achieved in industry by partially improving the calcination process of NH 4 VO 3 in large-scale rotary kilns.
危险品化学品经营许可证（带存储）