粉煤灰综合利用过程中汞的二次释放规律研究

我国粉煤灰年产生量4亿t左右,近年来利用率稳定在65%～68%,主要利用方式包括建材生产、道路施工、建筑工程和农业利用.建材生产包括高温工序,可能存在粉煤灰中汞的二次释放.本研究设计实验模拟了水泥生产、蒸养砖生产的主要环境因素,利用程序升温脱附的方法研究粉煤灰利用过程中的汞迁移转化规律,并对全国范围内粉煤灰利用过程汞的二次释放量做出估算.研究发现,粉煤灰中的汞以HgCl2(Hg2Cl2)、HgS和HgO的形式存在;水泥生产过程中,粉煤灰中98%以上的汞会释放;蒸养砖生产过程中,粉煤灰中汞的平均释放率为28%,释放率主要受到粉煤灰中的HgCl2(Hg2Cl2)比例的影响.我国粉煤灰利用过程中的汞二次排放量由2002年的4.07 t.a-1增至2008年的9.18 t.a-1,其中水泥行业的贡献率占到96.6%.     

新型低温Fe/AC脱硫剂的研究

将活性焦担载氧化铁制得Fe/AC脱硫剂用于烟气脱硫,在最经济的烟气脱硫温度窗口(120℃～250℃)显示出高的脱硫活性.考察操作条件对其脱硫活性的影响,并借助EXAFS和TPD表征技术对其内在原因进行探讨.Fe/AC脱硫剂在排烟温度下用于脱硫,其活性明显优于活性焦和纯Fe₂O₃,且载体炭无氧化烧损.Fe/AC吸硫后形成2种含硫物质:H₂SO₄和Fe₂(SO₄)₃,H₂O和O₂的存在可增加Fe/AC对SO₂的吸附硫容.由高比表面活性焦制得的Fe/AC有更高的脱硫活性,这源于活性组分Fe₂O₃在其上良好的分散性.Fe/AC用于脱硫应在适宜空速[(800L/(kg·h)]下操作.     

新型低温CuO/AC脱硫剂制备——煅烧温度对脱硫活性的影响

首次将炭载型ＣｕＯ／ＡＣ用于烟气脱硫,在最经济的烟气脱硫温度窗口（１２０～２５０℃）显示出高的脱硫活性．考查了煅烧温度和煅烧后脱硫剂的预氧化对脱硫活性的影响,并对脱硫剂进行了ＴＰＤ和ＥＸＡＦＳ表征．结果表明：经２５０℃煅烧的ＣｕＯ／ＡＣ脱硫剂具有最高的脱硫活性．２００℃煅烧,前驱体Ｃｕ（ＮＯ₃）₂未完全分解;高于２５０℃煅烧,活性组分ＣｕＯ被载体Ｃ部分还原为金属Ｃｕ 微晶,从而发生烧结、聚集,以上均导致脱硫剂活性的下降．尽管不同温度煅烧的ＣｕＯ／ＡＣ表现出大的脱硫活性差异,但吸硫后均生成同一反应产物ＣｕＳＯ₄．２５０℃煅烧的ＣｕＯ／ＡＣ脱硫剂Ｃｕ 以ＣｕＯ和Ｃｕ₂Ｏ形态存在,其中的Ｃｕ₂Ｏ在２００℃很容易氧化成ＣｕＯ     

Elemental mercury (Hg0) removal from coal syngas using magnetic tea-biochar: Experimental and theoretical insights

Mercury is ranked 3^rd as a global pollutant because of its long persistence in the environment. Approximately 65% of its anthropogenic emission (Hg⁰) to the atmosphere is from coal-thermal power plants. Thus, the Hg⁰ emission control from coal-thermal power plants is inevitable. Therefore, multiple sorbent materials were synthesized using a one-step pyrolysis method to capture the Hg⁰ from simulated coal syngas. Results showed, the Hg⁰ removal performance of the sorbents increased by the citric acid/ultrasonic application. T5CUF_0.3 demonstrated the highest Hg⁰ capturing performance with an adsorption capacity of 106.81 µg/g within 60 min at 200 °C under complex simulated syngas mixture (20% CO, 20% H₂, 10 ppmV HCl, 6% H₂O, and 400 ppmV H₂S). The Hg⁰ removal mechanism was proposed, revealing that the chemisorption governs the Hg⁰ removal process. Besides, the active Hg⁰ removal performance is attributed to the high dispersion of valence Fe₃O₄ and lattice oxygen (α) contents over the T5CUF_0.3 surface. In addition, the temperature programmed desorption (TPD) and XPS analysis confirmed that H₂S/HCl gases generate active sites over the sorbent surface, facilitating high Hg⁰ adsorption from syngas. This work represented a facile and practical pathway for utilizing cheap and eco-friendly tea waste to control the Hg⁰ emission.     

In situ IR,pulse reaction and TPD-ITD study of catalytic performance of room-temperature carbon monoxide oxidation on supported gold catalysts

With in situ IR, two different CO adsorption bands were detected on various chemical state gold catalysts. One band is attributed to the linear CO on an oxidized gold catalyst(2100 cm i ), the other one is ascribed to the bridged CO on metallic gold (2085 cm- i ). CO pulse reaction showed that Au/Fe203 catalyst had a room-temperature activity even in the presence of moisture. The produced CO2 was detained and more easily desorbed from supported gold catalyst than support oxide. TPD-IDT results indicated that the 02- superoxide ions are the possible active oxygen species.     

团絮状双效催化聚苯硫醚滤料反应参数及机理

以N-油酰基多肽表面活化聚苯硫醚滤料,以酸性KMnO₄在60~80℃操作温度下正向滴定,在氧化作用下实现活性组分氧化.实验研究了催化滤料的低温NO还原和Hg⁰氧化性能,并通过SEM、EDX及TPD表征手段对催化滤料物化结构进行分析.分别考察了（0.9）Mn-Ce-Fe-Co-O_x/PPS反应体系温度、气相O₂浓度、初始NO浓度、氨氮比（NSR）、入口SO₂浓度的最佳反应参数.结果表明,有效组分MnO_x、CeO_x、CoO_x、Fe₂O₃以团絮状均匀分散在纤维表面;在反应温度170℃、O₂≥5%、NO≤500×10^-6、氨氮比1.0、SO₂≤100 500×10^-6条件下,催化滤料对NO还原及Hg⁰氧化效率基本达到80%左右;程序升温脱附实验Hg-TPD结果表明SO₂的Hg⁰氧化促进作用机理于SO₃与Hg⁰非均相反应优于SO₂硫酸化反应,而NO-TPD结果则表明NO与O₂在PPS表面相互作用类型以吸附态亚硝酸盐为主,吸附态NO₂次之.     

Elimination of formaldehyde over Cu-Al2O3 catalyst at room temperature

Catalytic elimination of formaldehyde (HCHO) was investigated over Cu-Al2O3 catalyst at room temperature. The results indicated that no oxidation of HCHO into CO2 occurs at room temperature, but the adsorption of HCHO occurs on the catalyst surface.With the increase of gas hourly space velocity(GHSV) and inlet HCHO concentration, the time to reach saturation was shortened proportionally. The results of the in situ DRIFTS, Density functional theory calculations and temperature programmed desorption(TPD) showed that HCHO was completely oxidized into HCOOH over Cu-Al2O3 at room temperature. With increasing the temperature in a flow of helium, HCOOH was completely decomposed into CO2 over the catalyst surface, and the deactivated Cu-Al2O3 is regenerated at the same time. In addition, although Cu had no obvious influence on the adsorption of HCHO on Al2O3, Cu dramatically lowered the decomposition temperature of HCOOH into CO2. It was shown that Cu-Al2O3 catalyst had a good ability for the removal of HCHO, and appeared to be promising for its application in destroying HCHO at room temperature.     

离子交换分子筛对NO吸附的研究

在２７３Ｋ条件下，考察了不同阳离子交换的ＺＳＭ－５型和Ｙ型两种分子筛对ＮＯ的吸附性能，得出了在２７３Ｋ时的可逆及不可逆吸附量，并对不可逆吸附的ＮＯ进行了程序升温脱附研究；对样品吸附ＮＯ的本质进行了讨论。