desorption step
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Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 17
Author(s):  
Unni Engedahl ◽  
Adam A. Arvidsson ◽  
Henrik Grönbeck ◽  
Anders Hellman

As transportation continues to increase world-wide, there is a need for more efficient utilization of fossil fuel. One possibility is direct conversion of the solution gas bi-product CH4 into an energy-rich, easily usable liquid fuel such as CH3OH. However, new catalytic materials to facilitate the methane-to-methanol reaction are needed. Using density functional calculations, the partial oxidation of methane is investigated over the small-pore copper-exchanged zeolite SSZ-13. The reaction pathway is identified and the energy landscape elucidated over the proposed motifs Z2[Cu2O] and Z2[Cu2OH]. It is shown that the Z2[Cu2O] motif has an exergonic reaction path, provided water is added as a solvent for the desorption step. However, a micro-kinetic model shows that neither Z2[Cu2O] nor Z2[Cu2OH] has any notable activity under the reaction conditions. These findings highlight the importance of the detailed structure of the active site and that the most stable motif is not necessarily the most active.



2018 ◽  
Vol 36 (3) ◽  
pp. 031303 ◽  
Author(s):  
Sonam D. Sherpa ◽  
Peter L. G. Ventzek ◽  
Myungsuk Lee ◽  
Gyeong S. Hwang ◽  
Alok Ranjan


RSC Advances ◽  
2018 ◽  
Vol 8 (56) ◽  
pp. 32102-32110 ◽  
Author(s):  
Kaname Okura ◽  
Kazunari Miyazaki ◽  
Hiroki Muroyama ◽  
Toshiaki Matsui ◽  
Koichi Eguchi

Ni/SrZrO3 and Ni/BaZrO3 catalysts showed high activity for ammonia decomposition since these supports promoted the nitrogen desorption step.



2017 ◽  
Vol 24 (3) ◽  
pp. 264-274
Author(s):  
JP Cruz-Tirado ◽  
Arnold Cabanillas ◽  
Raúl Siche ◽  
J Espina ◽  
Leonardo Díaz-Sánchez ◽  
...  

This work studies the adsorption of colored compounds in cane juice using a food-grade macroporous adsorber resin without functional groups. The adsorption equilibrium was studied through the adsorption isotherms at 30, 40, and 50 ℃. The absorbance at 420 nm was used to measure the concentration of colored compounds, which enables correlation of the residual concentration with the adsorbed concentration. Furthermore, the efficiency of the adsorption process was studied, from which it was observed that there was an improvement in efficiency with increasing resin content, while the increase in temperature was less important in the process. The kinetic study was performed using the Ibarz model and intraparticle diffusion model, which correctly account for the kinetics of the adsorption process. The adsorption kinetic constant was always greater than the desorption kinetic constant, indicating that the adsorption step predominates over the desorption step.



2017 ◽  
Vol 36 (1-2) ◽  
pp. 732-742
Author(s):  
Minchao Feng ◽  
Xiaolong Zhou ◽  
Wei Hu ◽  
Wenyan Wang ◽  
Chenglie Li

An integrated process for separation and utilization of light naphtha stock in refineries is discussed in this paper. Normal paraffins present in light naphtha streams are first separated from nonnormal paraffins by adsorption technology. The adsorbed n-paraffins are recovered and can be used as an ideal feedstock for steam cracking, meanwhile iso-pentane or iso-pentane and iso-hexane blends are recovered by rectification of the nonadsorbed effluent and used as necessary components for modern gasoline or aviation gasoline products. From the results for a model feedstock, an isothermal adsorption and purging desorption approach is selected. Optimum parameters consist of adsorption and desorption duration of 30 min at 180℃ for each, nitrogen stream LHSV of 240 h−1 in the desorption step, the dynamic capacity of the adsorbent reaches 0.042 g/g.



2013 ◽  
Vol 781-784 ◽  
pp. 111-114
Author(s):  
Neng Sheng Ye ◽  
Ya Li Xie ◽  
Chang Liu ◽  
Jian Li

In this paper, graphene was used as the adsorbent for peptide enrichment, and followed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. To study the adsorptive property of graphene, peptide angiotensin II was chosen as the model target. The enrichment material was analyzed by MALDI-TOF MS directly without desorption step. As a result, graphene showed good adsorptive capacity for peptide. After enrichment, the peak intensity and the signal-to-noise ratio were obviously increased.



2008 ◽  
Vol 14 (5_suppl) ◽  
pp. 57-62 ◽  
Author(s):  
A. Ibarz ◽  
S. Garza ◽  
A. Garvín ◽  
J. Pagan

This paper deals with the effects of adsorbent resin upon kinetic process of peach juice adsorption de-coloration at different temperatures ranged from 10 °C to 50 °C. The adsorption equilibrium was quantified by means of adsorption isotherms in the range from 10 °C to 50 °C. Absorbance data at 420 nm were used to plot all the isotherms, which correlated reasonable well with the Freundlich and Langmuir isotherms. Also, the efficiency of the adsorption process was studied for different resin/juice ratios at different temperatures, from which it was observed that there was a notable improvement in efficiency as the resin content increased, while the increase in temperature was not so important in the process. The adsorption kinetics was also studied at 30 °C, for relationships of 1, 2, and 3 g resin/100g juice. A kinetic adsorption— desorption model in two simultaneous steps was proposed, where the adsorption step is considered as zero order and the desorption step as first order. This allows a global expression to be obtained that fits the experimental data appropriately to this kinetic type equation. The initial adsorption rate depended on the resin/juice relationship in such a way that the higher its value, the lower this relationship was. It was also shown that the equilibrium constant showed a similar tendency, its value being superior to the unit, which indicates that the retention stage over the resin prevails over the colored product desorption stage.



2006 ◽  
Vol 89 (3) ◽  
pp. 735-739 ◽  
Author(s):  
Pavlina Ivanova ◽  
Ditso Stratiev ◽  
Antoaneta Pavlova

Abstract A microcoulometric method is described for the determination of organic-halide pollutants at 2-2000 μg/L in natural, drinking, waste, and treated waters. The conditions for the adsorption of organic halides, using a microcolumn with activated charcoal-and for the desorption of inorganic halides-as well as for the pyrolysis process, were optimized for the successful determination of priority organic halide pollutants. An appropriate criterion was proposed to stop the desorption step. The mean recovery was 100.3%, and the mean relative standard deviation was 9.9%. The detection limit based on 3 times the standard deviation of the blank sample was 2 μg/L.



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