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analyze it.The experimental results show that coupling the photocatalytic reaction process and the ionic liquid extraction process can effectively remove organic sulfur in coal.Among them,the desulfurization rate of organic sulfur in the coal treated by [HO2MMim][HSO]-H2O-H2O2-TiOz (5:5:10:4)can reach 12.40%,in addition,an appropriate amount of water can improve the desulfurization rate of coal,but an excessive amount of aqueous solution will cause the concentration of hydrogen peroxide to decrease,and the organic sulfur desulfurization rate of coal will be lower.According Materials Studio analysis show that the hydroxyl radical (OH)generated by photocatalytic activity has strong oxidability,and the area near the oxygen atom ofOH is electronegative,which is easy to form S=O double bond with the positively charged S atom in thiophene by electrostatic attraction.In addition,the addition of ionic liquid makes the original lowest vacant orbital on the thiophene ring disappear and also lowers the energy level difference between the HOMO and the LUMO,making the reaction easier to proceed. Using COSMO analysis,it is found that the five-member heterocyclic structure of imidazole in [HO,MMim] [HSO]formed bonds with thiophene and sulfone molecules through van der Waals fofee.thus,sulfide was constantly extracted into the ionic liquid phase,and adding the oxidizer can make it easier for sulfone with higher chemical potential to enter the lower chemical potential ionic solution [HOMMim]S]than thiophene. KEY WORDS:photocatalytic oxidative desulfurization:thiophene.sulfone:hydroxyl radical:Materials Studio: COSMO 1引言 煤炭被认为是世界上最大的能源之一,但燃煤产性的硫化物是引发多种疾病和环境污 染的原因之一山。因此为了克服这些问题,煤必在使用前脱硫。总体来看,氧化脱硫具 有无耗氢、脱硫率高和对原料适应能力强等优点侬然是主要研究方法。它先利用氧化剂将 极性较弱的硫化物氧化为相应极性更高、茶子量更大的亚砜或砜类化合物,然后根据它们 不同的极性选择萃取或者吸附进行脱除。 光催化氧化作为高级氧化技术的一部分,它通过光催化剂吸收大于或等于半导体带隙 的入射光子能量,使体系中产生一种具有强氧化能力的羟基自由基,可以在低浓度下氧化 较难脱出的有机污染物,然后通过萃取将其分离2引。光催化氧化的萃取剂一般为有机溶剂, 易挥发,有毒,对人的身体损害很大。近年来由于离子液体具有挥发性低、稳定性高、萃 取能力强等特点受到关并泛应用于燃料中硫的高效脱除4山。作为萃取剂,离子液中像 咪唑环、吡啶环等基团有原子和共轭大π键,它们有很强的电荷吸引效应,而噻吩类硫 化物的π电子云密度他较大,离子液体与它接触后,会促使噻吩类的π键与离子液体的大π 键产生π-π络合效@从而增强离子液体与芳香硫化物之间的作用力:研究结果显示离 子液体能够有效溶胀、溶解并破坏煤结构,对煤的化学反应性产生一定的影响。鉴于离子 液体对煤结树的影响,国内外不少学者将离子液体用于煤脱硫脱灰,尤其是脱除有机硫的 实验研究何 计算机仿真在解决统计力学中的某些问题方面发挥着重要作用,利用美国Accelrys公 司开发的仿真软件“Materials Studio'”对结构的化学键理论、前轨道能量等进行分析,合理 解释脱硫机理和反应活性等。聂毅7采用Material Studio6.1中的Dmol3程序,研究了噻吩 在酸性离子液体作用下的脱硫机理,发现离子液体在作为萃取剂的同时还促进了加氢脱硫 过程中过渡态形成,起催化作用。目前己有少数文献通过COSMO-RS对萃取脱硫体系进行 了离子液体筛选,利用筛选出来的离子液体做萃取剂脱硫,同时可以预测性分析实践结果, 对化学反应进行机理研究。analyze it. The experimental results show that coupling the photocatalytic reaction process and the ionic liquid extraction process can effectively remove organic sulfur in coal. Among them, the desulfurization rate of organic sulfur in the coal treated by [HO2MMim][HSO4]-H2O-H2O2-TiO2(5:5:10:4)can reach 12.40%, in addition, an appropriate amount of water can improve the desulfurization rate of coal, but an excessive amount of aqueous solution will cause the concentration of hydrogen peroxide to decrease, and the organic sulfur desulfurization rate of coal will be lower. According Materials Studio analysis show that the hydroxyl radical (·OH) generated by photocatalytic activity has strong oxidability, and the area near the oxygen atom of ·OH is electronegative, which is easy to form S=O double bond with the positively charged S atom in thiophene by electrostatic attraction. In addition, the addition of ionic liquid makes the original lowest vacant orbital on the thiophene ring disappear and also lowers the energy level difference between the HOMO and the LUMO, making the reaction easier to proceed. Using COSMO analysis, it is found that the five-member heterocyclic structure of imidazole in [HO2MMim] [HSO4] formed bonds with thiophene and sulfone molecules through van der Waals force, thus, sulfide was constantly extracted into the ionic liquid phase, and adding the oxidizer can make it easier for sulfone with higher chemical potential to enter the lower chemical potential ionic solution [HO2MMim][HSO4] than thiophene. KEY WQRDS: photocatalytic oxidative desulfurization; thiophene, sulfone; hydroxyl radical; Materials Studio; COSMO 1 引言 煤炭被认为是世界上最大的能源之一,但燃煤产生的硫化物是引发多种疾病和环境污 染的原因之一[1]。因此为了克服这些问题,煤必须在使用前脱硫。总体来看,氧化脱硫具 有无耗氢、脱硫率高和对原料适应能力强等优点依然是主要研究方法。它先利用氧化剂将 极性较弱的硫化物氧化为相应极性更髙、分子量更大的亚砜或砜类化合物,然后根据它们 不同的极性选择萃取或者吸附进行脱除。 光催化氧化作为高级氧化技术的一部分,它通过光催化剂吸收大于或等于半导体带隙 的入射光子能量,使体系中产生一种具有强氧化能力的羟基自由基,可以在低浓度下氧化 较难脱出的有机污染物,然后通过萃取将其分离[2,3]。光催化氧化的萃取剂一般为有机溶剂, 易挥发,有毒,对人的身体损害很大。近年来由于离子液体具有挥发性低、稳定性高、萃 取能力强等特点受到关注并广泛应用于燃料中硫的高效脱除[4-11]。作为萃取剂,离子液中像 咪唑环、吡啶环等基团有N原子和共轭大 π 键,它们有很强的电荷吸引效应,而噻吩类硫 化物的 π 电子云密度也较大,离子液体与它接触后,会促使噻吩类的 π 键与离子液体的大 π 键产生 π-π 络合效应,从而增强离子液体与芳香硫化物之间的作用力 [12];研究结果显示离 子液体能够有效溶胀、溶解并破坏煤结构,对煤的化学反应性产生一定的影响。鉴于离子 液体对煤结构的影响,国内外不少学者将离子液体用于煤脱硫脱灰,尤其是脱除有机硫的 实验研究[13-16]。 计算机仿真在解决统计力学中的某些问题方面发挥着重要作用,利用美国 Accelrys 公 司开发的仿真软件“Materials Studio”对结构的化学键理论、前轨道能量等进行分析,合理 解释脱硫机理和反应活性等。聂毅[17]采用 Material Studio 6.1 中的 Dmol3 程序,研究了噻吩 在酸性离子液体作用下的脱硫机理,发现离子液体在作为萃取剂的同时还促进了加氢脱硫 过程中过渡态形成,起催化作用。目前己有少数文献通过 COSMO-RS 对萃取脱硫体系进行 了离子液体筛选,利用筛选出来的离子液体做萃取剂脱硫,同时可以预测性分析实践结果, 对化学反应进行机理研究[18]。 录用稿件,非最终出版稿
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