ABSTRACT
Slow progress in discovering new catalysts to circumvent the problem of ammonium bisulfate (NH4HSO4, ABS) poisoning has hindered further development of selective catalytic reduction (SCR) technology of NOx with ammonia (from numerous industrial processes) in afterburning systems at temperatures below dew point of ABS (typically between 280 °C and 320 °C). Recently, we have explored the use of atomically dispersed Mo species on TiO2 particles (hereafter denoted as MoO3/TiO2) as highly efficient catalyst for NH3-SCR reaction. In the present study, it will be shown that this type of catalyst is highly resistant to ABS poisoning for NH3-SCR reaction, overcoming a major issue afflicting the application of commercial V2O5-WO3/TiO2 catalyst at temperatures below the dew point of ABS. Aberration-corrected scanning transmission electron microscopy (STEM) suggests that most of the Mo species are present in atomically dispersed form in the MoO3/TiO2 catalyst. SO2 oxidation measurements show that the MoO3/TiO2 catalyst exhibits a substantially lower SO2 oxidation rate compared to the commercial V2O5-WO3/TiO2, mitigating ABS formation. Furthermore, decomposition of ABS on MoO3/TiO2 surface is found to be extremely facile. Temperature-programmed surface reaction (TPSR) with NO shows that the decomposition temperature of ABS over MoO3/TiO2 is 70 °C lower than that found on the commercial V2O5-WO3/TiO2 catalyst. Our investigations provide valuable information for the development of NH3-SCR catalysts with exceptional resistance to ABS poisoning for NOx emission control.
ABSTRACT
Our work sheds light on using the O 2p-band center as a useful electronic descriptor for understanding the variations in catalytic reducibility of transition metal oxides (TMOs) and the promotional effect of MnO2 during catalytic benzene combustion. The "volcano"-type activity plot, in conjunction with the reduction characteristic of the TMOs, ultimately reflects the Sabatier principle, which states that a good catalyst (i.e., MnO2) balances the capability of oxygen abstraction and uptake in the case of benzene combustion.
ABSTRACT
OBJECTIVE: To understand the perception on roles of gender and decision-making regarding family affairs among married women and its impact on the utilization of perinatal care. METHODS: Clustering sampling was conducted to select 1227 married women with at least a child aged from 0 to 7 years old, from Hebei, Hubei and Sichuan provinces. All women were interviewed using a uniform questionnaire during Nov.-Dec. 2004. RESULTS: The overall proportion of women who had relatively poor perception of gender role was 65.1%. 59.3% of the women agreed that "husband's health is more important than wife's in the family" versus 39.7% of interviewed women agreed that "man is more suitable for leadership than woman". In 46.2% of the families, wife and husband shared the responsibility of decision making on family affairs. In 16.2% of the families women played a decisive role, while 67.1% of interviewed women had to get the approval of her husband when spending money on daily necessities. When there were different opinions between the couples, husband usually made the final decision in 20.5% of all the families versus 17.4% of families where wife made the final decision. In total,the proportion of women who had somehow rights on family affairs was 64.1%. The coverage rate of antenatal care was 91.0%, and 65.3% women who received antenatal care got the first antenatal visit during the first trimester and the proportion of women who had at least five antenatal visits was 39.7%. The institutional delivery was 59.3% among all the women. Perception of gender role was not a predictor for antenatal care utilization, but it was predictive of institutional delivery. Education was quite a significant predictor on perinatal care utilization. CONCLUSION: Efforts should be strengthened to improve women's awareness and to increase their perception on gender role in the families so that more women could achieve quality perinatal care.
