Jiao Jing Zhang,Wen Yi Wang,Guo Jian Wang,Cheng Kai,Hua Song,Lu Wang
A model natural gas consisting of hydrogen sulfide, nitrogen and oxygen mixture was used to simulate materials to test the performance of an amine-modified MCM-41 adsorbent prepared by the impregnation method. The adsorbent was characterised by X-ray diffraction analysis, Brunauer–Emmett–Teller analysis, Fourier-transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The results showed that more molecules are able to penetrate the pores following modification, resulting in rapid structural collapse, thus lowering the diffraction intensity. Although the capacity of amine-modified MCM-41 decreased the physical adsorption, chemisorption increased significantly. (3-Aminopropyl)trimethoxysilane/MCM-41 was found to exhibit a good performance for H2S desulfurisation. At 45 °C the breakthrough time was 186 min, the saturated sulfur capacity was 134.38 mg g−1 and the degree of desulfurisation was 54.19%. The adsorption isotherm and kinetics were investigated and the relevant parameters were obtained. The results showed that the adsorption isotherm could be well fitted by the Langmuir model and the maximum adsorption capacities increased with increase of temperature. The adsorption kinetics could be represented by the Bangham model, which suggested that chemical reaction seemed significant in the rate-controlling adsorption step. The adsorption process was spontaneous and exothermic.
Yi Yuan,Lijia Huang,Murat Yılmaz,Tian C. Zhang,Yuan Wang,Shaojun Yuan
To improve their low-temperature desulfurization performance, the activated carbon-based materials have typically been modified by either metal oxide loading or nitrogen doping. However, most of the aforementioned materials are limited to only one of the above modification methods, resulting in relatively poor desulfurization performance. Herein, a novel MgFe 2 O 4 -loaded N -doped biochar (MgFe 2 O 4 @NBC) was fabricated by one-pot pyrolysis of a nitrogen containing precursor of g-C 3 N 4 , cooked rice waste, and metal salts for efficient low-temperature desulfurization of H 2 S. Different fabrication conditions such as pyrolysis temperature and the nitrogen mixing ratio (i.e., the mass ratio of cooked rice waste to g-C 3 N 4 ) have been extensively studied. The optimized MgFe 2 O 4 @NBC-500–2 sample delivered a superior breakthrough capacity of 1052.83 mg/g in an atmosphere of O 2 content of 20% and relative humidity of 80% at 25 °C, and demonstrated high tolerance and stability of desulfurization performance to harsh environmental conditions with 80% relative humidity and no oxygen. The desulfurization mechanism of H 2 S on the surfaces of the MgFe 2 O 4 @NBC composites was attributed to the synergistic effects of reactive adsorption and catalytic oxidation process. The composite also demonstrated excellent reusability, retaining 85% of the initial breakthrough capacity after 5 recycled uses. Therefore, the as-prepared MgFe 2 O 4 @NBC composite offers a potentially promising carbon-based desulfurizers for practical applications in the low-temperature desulfurization field.
Bin Meng,Erping Cao,Liwei Jia,Yuhua Zheng,Yanbin Cui
A variety of Cu-Fe oxide supported on Na 2 CO 3 -modified activated carbon (CuFeNaAC-X) catalysts were prepared via the impregnation and calcination methods and their desulfurization performance was evaluated at low-temperature. By optimizing the loading content of Cu-Fe, the sulfur capacity of the CuFeNaAC-5 reached a maximum of 430.09 mg/g, surpassing most activated carbon (AC) catalysts. EPR testing revealed that the loading of Cu-Fe oxide can activate oxygen to form superoxide radicals ( O 2 - ·), thereby promoting the catalytic oxidation of H 2 S. XPS testing revealed that upon loading of Cu-Fe oxide, the formation of FeOOH can facilitate the catalytic oxidation of H 2 S to sulfur (S) through a chain reaction. Combining EPR and XPS analyses, Na 2 CO 3 modification modulates the content of O 2 - ·, directing the formation of S and then significantly improving the catalyst’s desulfurization efficiency. Furthermore, CO 2 -TPD testing revealed that Na 2 CO 3 modification promotes the ionization of H 2 S to HS - , thereby enhancing the catalyst’s desulfurization performance. Based on the distribution of sulfur species in used catalysts, and the results of characterizations, a possible desulfurization mechanism of CuFeNaAC-X has been proposed.
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