Influence of chemisorbed carbon monoxide on subsequent physical adsorption of nitrogen

1957 ◽  
Vol 46 (2) ◽  
pp. 120-133 ◽  
Author(s):  
V. Srinivasan
Keyword(s):  
Carbon Monoxide ◽  
Physical Adsorption ◽  
Adsorption Of Nitrogen

scholarly journals Sorption and Diffusion Properties of H- and Modified Forms of ZSM-5 Zeolites

1996 ◽  
Vol 13 (6) ◽  
pp. 495-508 ◽  
Author(s):  
P. Hudek ◽  
D. Bobok ◽  
A. Smiešková ◽  
Z. Židek
Keyword(s):  
Physical Adsorption ◽  
Gravimetric Method ◽  
Equilibrium Concentration ◽  
Sorption Isotherms ◽  
Effective Diffusivity ◽  
Micropore Volume ◽  
Unit Cell ◽  
Adsorption Of Nitrogen ◽  
Effective Diffusivities ◽  
Modified Forms

The sorption properties of samples of H-ZSM-5 zeolite and their forms modified with P, B and Mg were determined by the physical adsorption of nitrogen and evaluated by BET isotherm and t-plot methods. The diffusivities of the samples were measured using a new flow gravimetric method involving the sorption of p- and o-xylenes. The BET specific surface area decreased from 358 m2/g to 35–90 m2/g mainly because of a decrease in micropore volume as determined by the t-plot method. The rate of sorption of p-xylene on all the samples investigated followed Fick's second law of diffusion, leading to an effective diffusivity of ca. 1.7 × 10−11 m2/s, irrespective of whether the H-form or the modified forms were investigated. The sorption isotherms for o-xylene showed some unusual steps. Values for the effective diffusivities decreased from 2.6 × 10−12 m2/s for the H-form to 2.0–2.3 × 10−12 m2/s for the modified forms. The equilibrium concentration of o-xylene at P/P0 = 0.1 was only 0.38–0.68 mol/unit cell, while that of p-xylene was 4.40–5.98 mol/unit cell.

Potential Evaluation of Gray Clay as Adsorbent of Heavy Metals Zinc (II) and Lead (II)

2014 ◽  
Vol 798-799 ◽  
pp. 622-627
Author(s):  
Wellington Siqueira Lima ◽  
José Vanderley Nascimento Silva ◽  
Aline Cadigna Lima Patrício ◽  
Guilherme Costa Oliveira ◽  
Meiry Glaúcia Freire Rodrigues
Keyword(s):  
Heavy Metals ◽  
Factorial Design ◽  
Metal Removal ◽  
Physical Adsorption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Removal Capacity ◽  
Adsorption Of Nitrogen ◽  
Potential Evaluation ◽  
Good Percentage

The problems caused by contamination of heavy metals generate a growing need to implement technologies to reduce or eliminate them. This work aims to evaluate the potential of gray clay, the process of removal of zinc and lead from synthetic effluents in finite bath system. The clay was characterized by: X-ray diffraction, X-ray Spectroscopy Energy Dispersive and Physical Adsorption of Nitrogen. The tests were performed finite bath following a 22 factorial design, with the variables: pH and initial concentrations of metal. The clays were evaluated for their removal capacity and rate of metal removal. After the characterization and evaluation, it was found that the gray clay comprises clay of the groups of kaolinite and mica. The results of the factorial design shown that the adsorption of the metals zinc and lead can be developed with good percentage of removal.

Synthesis and characterization of mesoporous molecular sieves

2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Michal Horňáček ◽  
Pavol Hudec ◽  
Agáta Smiešková
Keyword(s):  
Molecular Sieves ◽  
Physical Adsorption ◽  
Mesoporous Molecular Sieves ◽  
X Ray Diffraction ◽  
Synthesis Time ◽  
Adsorbed Pyridine ◽  
Adsorption Of Nitrogen ◽  
Temperature Programmed ◽  
Different Content ◽  
Mcm 41

AbstractIn the synthesis of mesoporous molecular sieves of the type MCM-41, different cationactive surfactants and sources of silicon were used. Moreover, Al-MCM-41 samples with different content of aluminium were synthesized. MCM-41 and Al-MCM-41 were synthesized at elevated temperature in stainless-steel autoclaves. Prepared mesoporous molecular sieves were characterized by powder X-ray diffraction (XRD), physical adsorption of nitrogen at the temperature of −197°C, sorption capacity of benzene, and by infrared spectroscopy (FTIR). Acidity was measured for Al-MCM-41 by temperature programmed desorption of ammonia (TPDA) and by FTIR of adsorbed pyridine. Acid catalytic activity of Al-MCM-41 was tested by isomerization of o-xylene. Influence of the synthesis reproducibility, surfactant used, source of silicon, synthesis time, source of aluminium, and Si to Al mole ratio on the properties of mesoporous molecular sieves were evaluated.

Adsorption Properties of ZSM-5 Zeolites

1998 ◽  
Vol 63 (2) ◽  
pp. 141-154 ◽  
Author(s):  
Pavol Hudec ◽  
Agáta Smiešková ◽  
Zdenek Židek ◽  
Milan Zúbek ◽  
Petr Schneider ◽  
...  
Keyword(s):  
Crystal Size ◽  
Physical Adsorption ◽  
Hysteresis Loops ◽  
Low Pressure ◽  
Adsorption Properties ◽  
Relative Pressure ◽  
Small Crystals ◽  
Bet Method ◽  
Adsorption Of Nitrogen ◽  
Microporous Solids

Adsorption properties determined by physical adsorption of nitrogen for a series of ZSM-5 zeolite samples with various Si/Al ratios and different crystal size were compared. In addition to the BET method, the t-plot method was used to determine the microporosity of samples. Very small crystals of ZSM-5 zeolites, generally below 1 μm, with Si/Al ratio between 14 and 21 exhibit adsorption isotherms typical for purely microporous solids. Samples with Si/Al ratios larger than (about) 95 show low-pressure steps and hysteresis loops and, depending on crystal morphology, also high-pressure hysteresis loops. The low-pressure steps were associated with steps on t-plots which showed two linear parts. Small increase of adsorption up to relative pressure 0.2 is characteristic for samples with Si/Al ratios between 25 and 50.

Synthesis of Ni-Mo-W Sulfide Nanorods as Catalyst for Hydrodesulfurization of Dibenzothiophene

2008 ◽  
Vol 8 (12) ◽  
pp. 6406-6413 ◽  
Author(s):  
F. Paraguay-Delgado ◽  
R. García-Alamilla ◽  
J. A. Lumbreras ◽  
E. Cizniega ◽  
G. Alonso-Núñez
Keyword(s):  
Electron Microscopy ◽  
Physical Adsorption ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Precursor ◽  
Transmission Electron ◽  
Adsorption Of Nitrogen ◽  
Diffraction Patterns ◽  
Scanning Electron

Two trimetallic sulfurs, MoWNiS and MoWSNi, were synthesized to be used as a catalyst in hydrodesulfurization reactions. The mixed oxide mesoporous nanostructured MoO3-WO3 with an Mo:W atomic ratio of 1:1 was used as the precursor. The first catalyst was prepared by impregnating nickel in the oxide precursor and then subsequent sulfiding with an H2S/H2 mix at 400 °C for 2 hours. The second catalyst was prepared by sulfiding the precursor and then impregnating the nickel, and finally reducing the material with a H2/N2 at 350 °C. In both catalysts the Mo:W:Ni atomic ratio was maintained at 1:1:0.5. The materials obtained were characterized by physical adsorption of nitrogen, X-ray diffraction, scanning electron microscopy, transmission electron microscopy. Furthermore, the materials obtained were evaluated by a dibenzothiophene hydrodesulfuration reaction. The diffraction patterns show that both materials are polycrystalline and mainly of MoS2 and WS2 phases.

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