scholarly journals Impact of Na+ and Ca2+ Cations on the Adsorption of H2S on Binder-Free LTA Zeolites

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Annika Starke ◽  
Christoph Pasel ◽  
Christian Bläker ◽  
Tobias Eckardt ◽  
Jens Zimmermann ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Fixed Bed ◽  
Exchange Equilibrium ◽  
Weakly Bound ◽  
Zeolite Lattice ◽  
Adsorption Sites ◽  
Sodium Cations ◽  
Cation Position ◽  
Binder Free ◽  
Exchange Degree

Hydrogen sulfide is removed from natural gas via adsorption on zeolites. The process operates very effectively, but there is still potential for improvement. Therefore, in this article, the adsorption of hydrogen sulfide was investigated on eight LTA zeolites with different cation compositions. Starting with the zeolite NaA (4 A), which contains only Na+ cations, the Ca2+ cation content was gradually increased by ion exchange. Equilibrium isotherms from cumulative breakthrough curve experiments in a fixed-bed adsorber at 25°C and 85°C at 1.3 bar (abs.) were determined in the trace range up to a concentration of 2000 ppmmol. From a comparison of the isotherms of the different materials, a mechanistic proposal for the adsorption is developed, taking into account the specific positions of the cations in the zeolite lattice when the degree of exchange is increased. The shape of the isotherms indicates two energetically different types of adsorption sites. It is assumed that two mechanisms are superimposed: a chemisorptive mechanism with dissociation of hydrogen sulfide and covalent bonding of the proton and the hydrogen sulfide ion to the zeolite lattice and a physisorptive mechanism by electrostatic interaction with the cations in the lattice. As the degree of exchange increases, the proportion of chemisorption sites seems to decrease. Above an exchange degree of 50%, only evidence of physisorption can be found. It is shown that this finding points to the involvement of weakly bound sodium cations at cation position III in the chemisorption of hydrogen sulfide.

Preparation of Sorbent Loaded with Nano-CuO for Room Temperature to Remove of Hydrogen Sulfide

2013 ◽  
Vol 475-476 ◽  
pp. 1329-1333 ◽  
Author(s):  
Fen Li ◽  
Jin Wei ◽  
Ying Yang ◽  
Guang Hui Yang ◽  
Tao Lei
Keyword(s):  
Grain Size ◽  
Hydrogen Sulfide ◽  
Metal Oxide ◽  
Copper Oxide ◽  
Calcination Temperature ◽  
Room Temperature ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Coconut Shell ◽  
Load Rate

In this paper, an efficient metal oxide sorbents for the deep removal of H2S were synthesized using equal volume impregnation (EVIM) method. Modified coconut shell charcoal was selected as support to deposite the particles of copper oxide onto the surface. And copper nitrate were selected as the active component precursors in the preparation process of sorbents. Sorption experiments were carried out at room temperature in fixed-bed reactor. The grain size and crystal form of loading metals were characterized by X-ray diffraction (XRD). We investigated the effects of modifier onto coconut shell charcoal, load rate of metal oxide and calcination temperature on the desulfurization activity of the sorbent. Results show that the best modifier for coconut shell charcoal is KOH, which is significantly better than the other modifiers. And the optimum load rate is 20%(wt), the optimum calcination temperature is 300°C. Copper oxide onto the surface of modified coconut shell charcoal proved to be monoclinic nanoparticles with grain size of 18.7nm. Sulfidation test was carried out on the condition of i) the concentration of hydrogen sulfide gas (mixed with nitrogen ) is 1024.2ppm and ii) gas velocity is 20ml/min, iii) 0.1g sample in the middle of the fixed-bed reactor (length: 450 mm, interior diameter: 5 mm) to test. The sample show excellent sulfur removal efficiency and its breakthrough time is up to 287 min on this condition.

scholarly journals Facile stabilization of a cyclodextrin metal–organic framework under humid environment via hydrogen sulfide treatment

RSC Advances ◽  
2019 ◽  
Vol 9 (32) ◽  
pp. 18271-18276 ◽  
Author(s):  
Duo Ke ◽  
Jun-Feng Feng ◽  
Di Wu ◽  
Jun-Bo Hou ◽  
Xiao-Qin Zhang ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Water Adsorption ◽  
Metal Organic Framework ◽  
Moisture Resistance ◽  
Adsorption Sites ◽  
Humid Environment ◽  
Metal Organic ◽  
Metal Ligand ◽  
Organic Framework

The moisture stable γ-CD-K-MOF was obtained by simply treating MOF with H2S gas. H2S acting as new water adsorption sites protected the metal–ligand bonds from water attack and thus enhanced the moisture resistance of γ-CD-K-MOF.

Removal of hydrogen sulfide by clinoptilolite in a fixed bed adsorber

2002 ◽  
Vol 41 (9) ◽  
pp. 785-792 ◽  
Author(s):  
Sena Yaşyerli ◽  
İrfan Ar ◽  
Gülşen Doğu ◽  
Timur Doğu
Keyword(s):  
Hydrogen Sulfide ◽  
Fixed Bed

scholarly journals Hydrogen Sulfide Adsorption by Iron Oxides and Their Polymer Composites: A Case-Study Application to Biogas Purification

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4725
Author(s):  
Camilla Costa ◽  
Matteo Cornacchia ◽  
Marcello Pagliero ◽  
Bruno Fabiano ◽  
Marco Vocciante ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Surface Area ◽  
Fixed Bed ◽  
Cost Effective ◽  
Chemical Precipitation ◽  
Breakthrough Curves ◽  
Operating Conditions ◽  
Precipitation Method ◽  
Inert Matrix ◽  
Biogas Purification

An experimental study of hydrogen sulfide adsorption on a fixed bed for biogas purification is proposed. The adsorbent investigated was powdered hematite, synthesized by a wet-chemical precipitation method and further activated with copper (II) oxide, used both as produced and after pelletization with polyvinyl alcohol as a binder. The pelletization procedure aims at optimizing the mechanical properties of the pellet without reducing the specific surface area. The active substrate has been characterized in its chemical composition and physical properties by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), thermogravimetric analysis (TGA) and N2 physisorption/desorption for the determination of surface area. Both powders and pellets have been tested as sorbents for biogas purification in a fixed bed of a steady-state adsorption column and the relevant breakthrough curves were determined for different operating conditions. The performance was critically analyzed and compared with that typical of other commercial sorbents based on zinc oxide or relying upon specific compounds supported on a chemically inert matrix (SulfaTreat®). The technique proposed may represent a cost-effective and sustainable alternative to commercial sorbents in conventional desulphurization processes.

scholarly journals Numerical Investigation of Process Enhancement Using a Bifunctional Catalyst in a Dual Fluidized-Bed Reactor

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 530
Author(s):  
Katarzyna Bizon ◽  
Krzysztof Skrzypek-Markiewicz ◽  
Mateusz Prończuk
Keyword(s):  
Fluidized Bed ◽  
Chemical Reaction ◽  
Active Sites ◽  
Physical Adsorption ◽  
Equilibrium Constants ◽  
Fixed Bed ◽  
Process Intensification ◽  
Fluidized Bed Reactor ◽  
Adsorption Sites ◽  
Dual Fluidized Bed

The paper outlines the concept of process intensification and integration, with a particular focus on sorption-enhanced, solid-catalyzed chemical processes. An alternative and attractive solution to a system of parallel fixed-bed apparatuses is evaluated, which utilizes the solids’ circulation in a dual fluidized-bed reactor–regenerator system. This allows for continuous mode operation and greatly simplifies the control procedures. To illustrate some aspects related to the steady-state operation of such a dual system, a simplified mathematical model of two interconnected fluidized beds operating in the bubbling regime was developed. A generic reversible chemical reaction of the overall second-order, catalyzed by bifunctional pellets, integrating catalytic active sites and adsorption sites, was considered as a test case. The model was used to study the effects of the bed hydrodynamics, as well as of the chemical reaction and physical adsorption equilibrium constants. It was shown how the superposition of various chemical, physical and hydrodynamical phenomena affects the performance of the system.

Sorption and Diffusion of n-Heptane in 5A Zeolite

1974 ◽  
Vol 52 (15) ◽  
pp. 2717-2724 ◽  
Author(s):  
I. H. Doetsch ◽  
D. M. Ruthven ◽  
K. F. Loughlin
Keyword(s):  
Activation Energy ◽  
Chemical Potential ◽  
Zeolite Lattice ◽  
Adsorption Sites ◽  
Localized Adsorption ◽  
5A Zeolite ◽  
Equilibrium Data ◽  
Reported Data ◽  
And Diffusion ◽  
Sorbate Concentration

Kinetic and equilibrium data for sorption of n-heptane in 5A zeolite are presented and discussed in relation to previously reported data for the C2–C4 hydrocarbons in the same zeolite.A satisfactory interpretation of the equilibrium data is obtained on the basis of a simple theoretical model in which it is assumed that there are, within each cavity of the zeolite lattice, two distinct and energetically different adsorption sites. These sites may correspond to the region close to the cavity wall in which adsorption is energetically favorable, giving rise to localized adsorption, and the central region of the cavity in which the sorbate is less strongly bound with greater rotational and translational freedom. The differential diffusivity increases strongly with sorbate concentration and, as with the lighter hydrocarbons, the form of this concentration dependence may be satisfactorily explained by considering the driving force for the transport process to be the gradient of chemical potential. The limiting diffusional activation energy for n-heptane is 7.5 kcal and this value is somewhat higher than the activation energy for the lighter paraffins.

Removal of hydrogen sulfide using palygorskite in a fixed bed adsorber

2012 ◽  
Vol 66 (8) ◽  
pp. 1794-1798
Author(s):  
T. Higuchi ◽  
Q. Zhang ◽  
M. Sekine ◽  
T. Imai ◽  
K. Yamamoto
Keyword(s):  
Hydrogen Sulfide ◽  
Adsorption Capacity ◽  
Low Cost ◽  
Fixed Bed ◽  
High Specific Surface Area ◽  
Raw Material ◽  
H2s Adsorption ◽  
Silicate Clay ◽  
Efficient Adsorbent ◽  
Aluminium Silicate

This work describes the use of a novel palygorskite, a type of magnesium aluminium silicate clay possessing a high specific surface area and pore surface activity, as a low cost and highly efficient adsorbent for hydrogen sulfide (H2S) removal. Adsorption of H2S on palygorskite pretreated with acid or base was investigated in a fixed bed adsorber. The samples after base pretreatment had better dynamic adsorption performances than raw material and samples pretreated with acid. The H2S adsorption capacity decreased with an increase in inlet H2S concentration. This can be interpreted by the fact that H2S adsorption on the surface of palygorskite is chemisorption. The adsorption capacity increased from 25 to 50 °C, then decreased from 50 to 100 °C, which indicates that chemisorption took place and its better reaction temperature was around 50 °C.

scholarly journals Influence of Substrate Concentration on Kinetic Parameters of Ethanol Dehydration in MFI and CHA Zeolites and Relation of These Kinetic Parameters to Acid–Base Properties

Catalysts ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 51
Author(s):  
Pavel Čičmanec ◽  
Jiří Kotera ◽  
Jan Vaculík ◽  
Roman Bulánek
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Catalyst Deactivation ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Ethanol Dehydration ◽  
Acid Base ◽  
Diffusion Limitations ◽  
Zeolite Lattice ◽  
Base Properties

The catalytic activity of zeolites is often related to their acid–base properties. In this work, the relationship between the value of apparent activation energy of ethanol dehydration, measured in a fixed bed reactor and by means of a temperature-programmed surface reaction (TPSR) depending on the amount of ethanol in the zeolite lattice and the value of activation energy of H/D exchange as a measure of acid–base properties of MFI and CHA zeolites, was studied. Tests in a fixed bed reactor were unable to provide reliable reaction kinetics data due to internal diffusion limitations and rapid catalyst deactivation. Only the TPSR method was able to provide activation energy values comparable to the activation energy values obtained from the H/D exchange rate measurements. In addition, for CHA zeolite, it has been shown that the values of ethanol dehydration activation energies depend on the amount of ethanol in the CHA framework, and this effect can be attributed to the substrate clustering effects supporting the deprotonation of zeolite Brønsted centers.

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