SO_2在N,N’-二(2-羟丙基)哌嗪硫酸盐水溶液中气液平衡数据的测定

采用静态法,在耐高浓度SO2腐蚀的常压装置中,测定SO2在N,N′-二(2-羟丙基)哌嗪(HPP)硫酸盐水溶液中的气液平衡数据。实验温度283.15~323.15 K,SO2分压7.50~101.12 kPa,HPP浓度5%~30%。研究结果表明,SO2溶解度随HPP浓度增大而显著增大,随气相中SO2浓度的增大而增大,随温度的升高而降低。在实验浓度范围内,同一温度及HPP浓度下,SO2分压增大,溶解度系数值相应增大,SO2在HPP硫酸盐溶液中的溶解过程不符合亨利定律。     

酸性组分对N,N′-二（2-羟丙基）哌嗪吸收/解吸SO2性能的影响

通过添加硫酸、盐酸和氢氟酸模拟研究了SO3、HCl和HF三种酸性气体对N,N’-二(2-羟丙基)哌嗪(HPP)吸收解吸SO2性能的影响。研究结果表明,随着吸收液中硫酸、盐酸和氢氟酸的浓度逐渐增大,吸收液的饱和吸收量和脱硫率逐渐降低,解吸率逐渐增大。添加相同浓度H+的硫酸和盐酸对HPP吸收SO2性能的影响效果基本相当,且大于相同浓度H+的氢氟酸。每摩尔吸收液中添加0.5 mol硫酸或1 mol盐酸,吸收液饱和吸收量减少0.47mol mol 1;每摩尔吸收液中添加1 mol氢氟酸,饱和吸收量减少0.44 mol mol 1,饱和吸收量的理论计算值与实验值偏差率小于±1%。     

低分压SO_2在N,N′-二(2-羟乙基)哌嗪水溶液中的溶解度

采用半动态法测定了在298,308 K下低分压SO2在N,N′-二(2-羟乙基)哌嗪水溶液中的溶解度,建立了该过程基于化学反应平衡和吸收相平衡的数学模型。结果表明:在较低的SO2分压下,SO2的溶解度随着分压的增加而急剧增加,当溶解度达到一定值时,溶解度随着分压的增加而缓慢增加;pH值越大、温度越低及N,N′-二(2-羟乙基)哌嗪浓度越高越有利于SO2的溶解,模型得出的溶解度与实验值符合较好。     

N,N′-1,4-二对甲苯磺酰高哌嗪合成研究

以N-甲基吡咯烷酮为溶剂,NaOH为缚酸剂,1,3-二氯丙烷为环合试剂,合成N,N′-1,4-二对甲苯磺酰基高哌嗪,探究反应时间、反应物物料比、反应温度和NaOH用量对N,N′-1,4-二对甲苯磺酰基高哌嗪产率的影响。结果表明,各因素影响顺序为：碱量>温度>反应物物料比,在5 mmol N,N′-二对甲苯磺酰乙二胺,7.969 mmol 1,3-二氯丙烷,0.548 g NaOH的条件下,123℃反应40 min,N,N′-1,4-二对甲苯磺酰基高哌嗪收率可达81.93%。利用二级反应机理,在115,125,135℃三个温度下,对N,N′-1,4-二对甲苯磺酰高哌嗪合成反应进行动力学分析,得到反应的活化能为76.233 kJ/mol。     

N,N'-二(2-羟丙基)哌嗪-硫酸钠-水三元体系相平衡测定与计算

采用等温溶解平衡法测定N,N′-二(2-羟丙基)哌嗪(HPP)?Na2SO4?H2O三元体系在273.15和298.15 K下的相平衡数据,采用湿渣法测定其平衡固相数据,绘制等温相图。用改进的单组分电解质Pitzer方程计算该体系中Na2SO4和Na2SO4?10H2O的溶解平衡常数,并对相平衡数据进行理论计算。结果表明,273.15 K时存在3个结晶区,298.15 K时存在4个结晶区。HPP的存在降低了Na2SO4和Na2SO4?10H2O的相转变温度,使298.15 K下的相图中存在Na2SO4的结晶区域,且273.15和298.15 K的相图中不存在纯HPP的结晶区域。理论计算与实验数据的均方根偏差不高于0.0290,表明相平衡数据计算值与实验值较吻合,证实了改进的单组分电解质Pitzer方程适用于该体系计算。     

烟气脱硫石膏溶液法制备α-半水石膏的工艺研究

研究了采用溶液法以烟气脱硫石膏制备α-半水石膏的工艺.结果表明,反应温度、pH值、盐溶液浓度、固液比等是影响烟气脱硫石膏脱水速度的主要因素,溶液pH值还影响α-半水石膏的形状;盐溶液浓度增大有利于α-半水石膏的生成,且在半水阶段停留时间长.在反应温度为110℃、pH值为6、盐溶液浓度为25%、固液比为1:(4～8)时,...     

1-(2-羟乙基)-4-(2-羟丙基)哌嗪基复合胺脱硫剂的合成与性能

以哌嗪(PZ)、环氧乙烷(EO)、环氧丙烷(PO)为原料,以水为溶剂,PZ先与EO反应后中间产物再与PO反应合成1-(2-羟乙基)-4-(2-羟丙基)哌嗪基复合胺脱硫剂.在PZ初始浓度为0.1 g/mL H2O,PZ:EO:PO摩尔比为1:0.8:1.2,PZ与EO、PO的反应温度分别为35℃、25℃,中间产物与PO在反应时间为150 min的优化条件下,所得复合胺脱硫剂成分为1-(2-羟乙基)-4-(2-羟丙基)哌嗪、N,N′-二(2-羟丙基)哌嗪、N-(2-羟乙基)哌嗪、N-(2-羟丙基)哌嗪、N,N′-二(2-羟乙基)哌嗪、N-(1-甲基-2-羟乙基)哌嗪和哌嗪,其对气体SO2的饱和吸收量为0.7218 mol/mol,解吸率为98.37％.     

N,N’-1,4-二对甲苯磺酰高哌嗪的合成

以甲醇钠为催化剂合成出N,N’-1,4-二对甲苯磺酰高哌嗪,考察了原料的物质的量比、反应时间、溶剂用量和相转移催化剂用量4种因素对反应收率的影响,较佳工艺条件为:N,N’-1,4-二对甲苯磺酰乙二胺0.02 mol时,N,N’-二对甲苯磺酰乙二胺和1,3-二溴丙烷的投料物质的量比1∶1.25,反应时间13 h,溶剂二甲基甲酰胺用量60 mL,苄基三乙基溴化铵用量0.6 g,总收率达65.65%。     

HPP吸收/解吸SO2气体工艺参数的研究

研究了N,N’-二(2-羟丙基)哌嗪(HPP)吸收/解吸SO2的工艺条件,考察了吸收液初始pH值和吸收温度对HPP吸收/解吸SO2性能的影响。结果表明,优化的HPP溶液吸收/解吸SO2的工艺条件为:吸收液初始pH值为6.00,吸收温度50℃,解吸方式为直接加热,解吸温度102℃,解吸时间2 h。其饱和吸收量为0.472 0 mol/mol,解吸率86.42%,氧化率为2.29%。     

用氨-酸法脱除工业烟气中低浓度SO2生产硫酸铵

简述用氨-硫酸法脱除烟气中低浓度SO2,并利用回收的SO2生产硫酸和硫酸铵的工艺过程;介绍利用该工艺技术在国内建成投产的第1套烟气脱硫工业装置的设计和运行概况.推荐将该项技术列为我国今后烟气脱硫的主要工艺技术加以推广.     

HPP吸收/解吸SO_2气体工艺参数的研究

研究了N,N’-二（2-羟丙基）哌嗪（HPP）吸收/解吸SO2的工艺条件,考察了吸收液初始pH值和吸收温度对HPP吸收/解吸SO2性能的影响。结果表明,优化的HPP溶液吸收/解吸SO2的工艺条件为：吸收液初始pH值为6.00,吸收温度50℃,解吸方式为直接加热,解吸温度102℃,解吸时间2 h。其饱和吸收量为0.472 0 mol/mol,解吸率86.42%,氧化率为2.29%。     

哌嗪类有机胺脱除二氧化硫性能及机理探讨

选择哌嗪（PZ）及其衍生物N,N'-双（2-羟乙基）哌嗪（BHEP）、N,N'-双（2-羟丙基）哌嗪（HPP）、1-（2-羟乙基）-4-（2-羟丙基）哌嗪（HEHPP）、1-（2-羟乙基）哌嗪（HEP）5种哌嗪类有机胺作为SO₂吸收剂,采用动态法在填料塔中吸收模拟烟气中的SO₂并对吸收剂进行热再生。4次循环吸收解吸实验结果表明：有机胺的碱性与位阻效应共同决定其脱硫性能。PZ的pK_a最大,对SO₂有较大的吸收容量,首次饱和吸收容量高达0.8428mol/mol,但难解吸且再生能耗高,首次解吸率仅为78.9%,4次循环后饱和吸收容量下降了54.3%,循环吸收能力较差;HEP吸收效果次于PZ,其解吸性能较PZ有所提高;双羟基哌嗪类二胺的pK_a最小,饱和吸收容量相对较低,平均不低于0.4mol/mol;解吸率高,平均保持在95%以上,且再生能耗低、稳定性好,其中HEHPP的脱硫性能介于BHEP和HPP之间。因此,双羟基哌嗪可作为新型高效脱硫剂。     

Stabilization of hydrogen peroxide using tartaric acids in Fenton and Fenton-like oxidation

The stabilization of hydrogen peroxide is a key factor in the efficiency of a Fenton reaction. The stability of hydrogen peroxide was evaluated in a Fenton reaction and Fenton-like reactions in the presence of tartaric acid as a stabilizer. The interactions between ferrous or ferric iron and tartaric acid were observed through spectroscopic monitoring at variable pH around pKa1 and pKa2 of the stabilizer. Ferric iron had a strong interaction with the stabilizer, and the strong interaction was dominant above pKa2. At a low pH, below pKa1, the stabilizing effect was at its maximum and the prolonged life-time of hydrogen peroxide gave a higher efficiency to the oxidative degradation of nitrobenzene. In Fenton-like reactions with hematite, the acidic conditions caused dissolution of iron from an iron oxide, and an increase in iron species was the result. Tartaric acid showed a stabilizing effect on hydrogen peroxide in the Fentonlike system. The stabilization by tartaric acid might be due to an inhibition of catalytic activity of dissolved iron, and the stabilization strongly depends on the ionization state of the stabilizer.     

Reduction of nitrogen dioxide by propene over acidic mordenites: influence of acid site concentration, formation of by-products and mechanism

The reduction of nitrogen dioxide to nitrogen by propene was studied over a variety of acidic mordenite zeolites differing in their Si : Al ratio and thus, in their concentration of acid sites. The formation of by-products was monitored applying an ion–molecule reaction (IMR) mass spectrometer. It was found that at fixed conditions the yield of nitrogen increases with increasing concentration of acid sites, confirming that acid sites are the active catalytic centres in the reaction. Apart from nitrogen and nitric oxide, acrylonitrile and ammonia are formed as nitrogen containing gas-phase products in the reaction. In separate experiments, it was shown that acrylonitrile is hydrolysed by water over the acidic zeolites to yield ammonia and acrylic acid. When acrylonitrile is used as reducing agent for nitrogen dioxide, formation of nitrogen is strongly enhanced in the presence of water. Water also has a promoting effect on the formation of nitrogen in the reaction between nitrogen dioxide and propene. Acrylonitrile and its product of hydrolysis, ammonia, are considered to be intermediates of nitrogen dioxide reduction to nitrogen by propene over acidic zeolites.     

Synthesis of cyclic carbonates from epoxides: Use of reticular oxygen of Al2O3 or Al2O3-supported CeOx for the selective epoxidation of propene

Reticular oxygen of Al₂O₃ or CeO_x supported on Al₂O₃ was used for the epoxidation of propene without any double bond cleavage. In batch reaction, Al₂O₃ alone was able to convert propene into propene oxide (PO) with 100% selectivity and 2% conversion of propene with a close to 3:1 ratio with respect to the number of Al(III) reduced to elemental Al. When Ce₂O₃/Al₂O₃ or CeO₂/Al₂O₃ was used, Al remained in its +3 oxidation state, while the Ce oxide was the oxidant as demonstrated by XPS analyses. CeO_x/Al₂O₃ was more active (propene conversion yield of 4–5%) but the selectivity was lower (70%) as PO was isomerized into acetone and propionaldehyde.

Interestingly the use of reticular oxygen very much improves the selectivity with respect to the use of pure O₂. In fact, while propene was more efficiently oxidized (10%) with O₂ in presence of Al₂O₃ or CeO_x/Al₂O₃, the selectivity was as low as 40% because C1 and C2 products were formed. However, the use of reticular oxygen represents a selective two-step technique for the use of molecular oxygen as oxidant of propene. The used oxides can be re-oxidized and the whole process can be further improved towards higher yields.

PO is quantitatively converted into propene carbonate by reaction with CO₂ in presence of Nb₂O₅.     

磺化石墨烯固体酸催化剂的制备及活性评价

石墨烯是由碳原子以sp₂杂化连接的单原子层构成的新型二维碳原子晶体,由于含有众多具有反应活性的碳碳双键,石墨烯纳米片表面很容易进行化学修饰键合有机官能团而改变其性质。采用改良Hummers法制备氧化石墨烯,通过磺化反应制备磺化石墨烯固体酸催化剂,通过FT-IR、元素分析和XPS等对其结构进行表征。将制备的氧化石墨烯和磺化石墨烯应用于催化纤维二糖的水解反应,以纤维二糖糖苷键的水解反应为模型考察其酸催化性能。结果表明,氧化石墨烯和磺化石墨烯中含有-COOH、-OH和-SO₃H等官能团,磺酸根密度分别为1.0 mmol·g^-1和2.2 mmol·g^-1,氧化石墨烯和磺化石墨烯具有与H₂SO₄相比拟的酸催化活性,尽管酸性强度和密度较低,但催化活性与H₂SO₄相当。     

Catalytic performance of indium-supported TiO2-ZrO2 for the selective reduction of nitrogen monoxide in the presence of oxygen

The catalytic activity of indium-supported TiO₂- ZrO₂ binary metal oxide for the selective reduction of NO with propene in the presence of oxygen was investigated. The supported indium caused a drastic enhancement of NO reduction activity of TiO₂-ZrO₂. It was suggested that the ``dispersed phase' of indium oxide, which is reduced at lower temperature in temperature-programmed reduction (TPR), is responsible for the high activity. Propene served as the most efficient reducing agent, while oxygenated hydrocarbons were not good ones. A reaction mechanism was proposed that N₂ is formed through the reaction of propene and NO₂, which was formed on the acid sites of TiO₂-ZrO₂, on the indium sites. This revised version was published online in July 2006 with corrections to the Cover Date.