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Effect of Humidity on the Sorption of H2S from Multicomponent Acid Gas Streams on Silica-Supported Sterically Hindered and Unhindered Amines
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-06-30 , DOI: 10.1021/acssuschemeng.0c02012
Claudia N. Okonkwo 1 , Hanjun Fang 1 , David S. Sholl 1 , Johannes E. Leisen 2 , Christopher W. Jones 1, 2
Affiliation  

The sorption of H2S on a silica-supported sterically hindered secondary amine and a supported unhindered tertiary amine is investigated using fixed bed breakthrough experiments. In situ Fourier transform infrared spectroscopy and computational analysis are used to elucidate the structure of the surface species formed during humid H2S sorption. Additionally, the cyclic stability of the amine-functionalized silica sorbent is assessed using NMR spectroscopy, N2 physisorption, and elemental analysis. For all sorbents under dry conditions, the physisorption of H2S on the amines led to low H2S sorption capacities, but under humid conditions, a strongly chemisorbed species is formed, which leads to an increase in the H2S sorption capacity. These findings are supported by density functional theory (DFT) calculations, which support the formation of a chemisorbed and stable HS species in the presence of H2O. As a result of the strongly bound species, the sorbents require humid temperature swing sorption–desorption cycles for efficient sorbent regeneration under the conditions studied, with temperature swings using dry gas failing to effectively desorb the H2S. For competitive H2S/CO2 sorption under mixed gas conditions (CH4/CO2/H2S/H2O), the selectivity for H2S sorption over CO2 is demonstrated to result from kinetic factors, with reaction barriers playing a major role under humid conditions. Overall, the structure of the silica framework and organic moieties are maintained for both sorbents after extended humid H2S exposure. The results in this work confirm the positive effect of humidity on the H2S sorption capacity of silica-supported sterically hindered and unhindered amines.

中文翻译:

湿度对多组分酸性气体流中H 2 S吸附在硅胶负载的位阻和无位胺上的影响

使用固定床穿透实验研究了H 2 S在二氧化硅负载的位阻仲胺和负载的无阻叔胺上的吸附。原位傅里叶变换红外光谱和计算分析被用来阐明在湿H 2 S吸附过程中形成的表面物质的结构。另外,使用NMR光谱,N 2物理吸附和元素分析评估胺官能化的二氧化硅吸附剂的循环稳定性。对于干燥条件下的所有吸附剂,H 2 S在胺上的物理吸附导致低H 2。S的吸附能力,但在潮湿条件下会形成强烈的化学吸附物质,从而导致H 2 S的吸附能力增加。这些发现是通过密度泛函理论支持(DFT)计算,其支持一个化学吸附和稳定HS的形成-在H的存在物种2 O.作为强烈结合物种的结果,吸附剂需要湿润变温吸附-要求的条件下有效的吸附剂再生解吸循环研究,在使用干燥气体不能有效解吸h温度波动2 S.对于竞争性ħ 2 S / CO 2混合气体的条件下吸附(CH 4 / CO 2/ H 2 S / H 2 O)中,H 2 S相对于CO 2的吸附选择性被证明是由动力学因素引起的,反应屏障在潮湿条件下起主要作用。总体而言,长时间暴露于湿H 2 S后,两种吸附剂的二氧化硅骨架和有机部分的结构均得以保持。这项工作的结果证实了湿度对二氧化硅负载的位阻胺和不受阻胺的H 2 S吸附能力的积极影响。
更新日期:2020-07-13
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