Modification of Activated Carbon KAU Surface Properties
The properties of oxidized activated carbon KAU treated at different temperatures in inert atmosphere were studied by means of DTA, Boehm titration, XPS and AFM methods and their catalytic activity in H2S oxidation was established. Three types of oxygen species exist on carbon catalysts surface. It...
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Brazhnyk, D.V. Bacherikova, I.V. Zazhigalov, V.A. Kowal, A. 2011-11-29T17:23:59Z 2011-11-29T17:23:59Z 2011 Modification of Activated Carbon KAU Surface Properties / D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal // Хімія, фізика та технологія поверхні. — 2011. — Т. 2, № 1. — С. 41-52. — Бібліогр.: 47 назв. — англ. 2079-1704 https://nasplib.isofts.kiev.ua/handle/123456789/29040 544.72 The properties of oxidized activated carbon KAU treated at different temperatures in inert atmosphere were studied by means of DTA, Boehm titration, XPS and AFM methods and their catalytic activity in H2S oxidation was established. Three types of oxygen species exist on carbon catalysts surface. It was shown that their catalytic activity in hydrogen sulfide oxidation correlated with relative content of OH-groups and charged oxygen species on carbons surface (O2.1 and O3.1 oxygen types with BE = 533.2–533.7 and 536.8–537.6 eV, respectively). The sample treated at 1000°C has very high activity in H2S oxidation and transforms up to 57 mmol H2S/g cat at 180°C. The vanadium/carbon KAU samples were prepared by three different methods (incipient wet impregnation and deposition-precipitation by NH4VO3 in aqueous medium, and in acetonitrile with VO(acac)2). It was established that synthesis in organic medium led to preparation of nanodispersed vanadia on carbon surface. The V/C samples were more active in H2S oxidation at 180° C than treated activated carbons. The sample prepared in organic medium had excellent activity in hydrogen sulfide oxidation and oxidized more than 132 mmol H2S/g cat without its deactivation. The formation of surface dense sulfur layer is the reason of catalysts deactivation in H2S selective catalytic oxidation. Методами ДТА, РФЕС, АСМ та титрування за Бьомом вивчені властивості окисленого активованого вугілля КАУ, термічно модифікованого при різних температурах в інертному середовищі. Каталітична активність синтезованих зразків досліджена в реакції окиснення H2S. На поверхні активованого вугілля встановлено присутність трьох типів кисневмісних частинок. Показано, що каталітична активність зразків в окисненні сірководню корелює з відносним вмістом ОН-груп та заряджених форм кисню на поверхні вугілля (О2.1 та О3.1 тип кисню з Езв. = 533,2-533,7 та 536,8-537,6 еВ, відповідно). Найактивніший зразок, модифікований при температурі 1000ºС, перетворив 57 ммоль H2S/г каталізатора при температурі реакції 180ºС. Зразки V/КАУ синтезовані трьома різними методами (просоченням по вологоємкості та осадженням з водного розчину NH4VO3, а також взаємодією с VO(acac)2 в середовищі ацетонітрилу). Було встановлено, що синтез в органічному середовищі спричиняє утворення нанодисперсних кластерів ванадію на поверхні активного вугілля. Зразки, які містять ванадій, більш активні в порівнянні з термічно модифікованим вугіллям в реакції окиснення H2S при температурі 180ºС. Зразок, синтезований в органічному середовищі, найактивнішій в реакції окиснення сірководню, перетворив більш ніж 132 ммоль H2S/г каталізатора без втрати активності. Покриття поверхні щільним шаром сірки, яка утворюється в результаті реакції, є причиною дезактивації каталізаторів в реакції селективного окиснення H2S. Методами ДТА, РФЭС, АСМ и титрования по Бёму изучены свойства окисленного активированного угля КАУ, термически модифицированного при различных температурах в инертной атмосфере. Каталитическая активность синтезированных образцов исследована в реакции окисления сероводорода. На поверхности активированного угля установлено присутствие трех типов кислородсодержащих частиц. Показано, что каталитическая активность образцов в окислении сероводорода коррелирует с относительным содержанием ОН-групп и заряженных форм кислорода на поверхности угля (О2.1 и О3.1 тип кислорода с Есв. = 533,2-533,7 и 536,8–537,6 эВ, соответственно). Наиболее активный образец, модифицированный при температуре 1000º С, окислил (превратил) 57 ммоль H2S/г катализатора при температуре реакции 180ºС. Образцы V/КАУ синтезированы тремя различными методами (пропиткой по влагоемкости и осаждением из водного раствора NH4VO3, а также взаимодействием с VO(acac)2 в растворе ацетонитрила). Было установлено, что синтез в органической среде обуславливает образование нанодисперсных кластеров ванадия на поверхности активного угля. Ванадийсодержащие образцы в реакции окисления H2S при температуре 180º С более активны в сравнении с термически модифицированным углем. Образец, синтезированный в органической среде, показал высокую активность в реакции окисления сероводорода, превратив более 132 ммоль H2S/г катализатора без его дезактивации. Покрытие поверхности сплошным слоем образовавшейся серы является причиной дезактивации катализаторов в реакции селективного окисления H2S. D.V. Brazhnyk thanks the financial support from National Academy of Sciences of Ukraine (grant for young scientists – resolution No 66, 06.04.05). The work was realized at partial support of NASU Program (Project No 12, 2006-2010). en Інститут хімії поверхні ім. О.О. Чуйка НАН України Хімія, фізика та технологія поверхні Modification of Activated Carbon KAU Surface Properties Mодификація властивостей поверхні активованого вугілля КАУ Модификация свойств поверхности активированного угля КАУ Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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| title |
Modification of Activated Carbon KAU Surface Properties |
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Modification of Activated Carbon KAU Surface Properties Brazhnyk, D.V. Bacherikova, I.V. Zazhigalov, V.A. Kowal, A. |
| title_short |
Modification of Activated Carbon KAU Surface Properties |
| title_full |
Modification of Activated Carbon KAU Surface Properties |
| title_fullStr |
Modification of Activated Carbon KAU Surface Properties |
| title_full_unstemmed |
Modification of Activated Carbon KAU Surface Properties |
| title_sort |
modification of activated carbon kau surface properties |
| author |
Brazhnyk, D.V. Bacherikova, I.V. Zazhigalov, V.A. Kowal, A. |
| author_facet |
Brazhnyk, D.V. Bacherikova, I.V. Zazhigalov, V.A. Kowal, A. |
| publishDate |
2011 |
| language |
English |
| container_title |
Хімія, фізика та технологія поверхні |
| publisher |
Інститут хімії поверхні ім. О.О. Чуйка НАН України |
| format |
Article |
| title_alt |
Mодификація властивостей поверхні активованого вугілля КАУ Модификация свойств поверхности активированного угля КАУ |
| description |
The properties of oxidized activated carbon KAU treated at different temperatures in inert atmosphere were studied by means of DTA, Boehm titration, XPS and AFM methods and their catalytic activity in H2S oxidation was established. Three types of oxygen species exist on carbon catalysts surface. It was shown that their catalytic activity in hydrogen sulfide oxidation correlated with relative content of OH-groups and charged oxygen species on carbons surface (O2.1 and O3.1 oxygen types with BE = 533.2–533.7 and 536.8–537.6 eV, respectively). The sample treated at 1000°C has very high activity in H2S oxidation and transforms up to 57 mmol H2S/g cat at 180°C. The vanadium/carbon KAU samples were prepared by three different methods (incipient wet impregnation and deposition-precipitation by NH4VO3 in aqueous medium, and in acetonitrile with VO(acac)2). It was established that synthesis in organic medium led to preparation of nanodispersed vanadia on carbon surface. The V/C samples were more active in H2S oxidation at 180° C than treated activated carbons. The sample prepared in organic medium had excellent activity in hydrogen sulfide oxidation and oxidized more than 132 mmol H2S/g cat without its deactivation. The formation of surface dense sulfur layer is the reason of catalysts deactivation in H2S selective catalytic oxidation.
Методами ДТА, РФЕС, АСМ та титрування за Бьомом вивчені властивості окисленого активованого вугілля КАУ, термічно модифікованого при різних температурах в інертному середовищі. Каталітична активність синтезованих зразків досліджена в реакції окиснення H2S. На поверхні активованого вугілля встановлено присутність трьох типів кисневмісних частинок. Показано, що каталітична активність зразків в окисненні сірководню корелює з відносним вмістом ОН-груп та заряджених форм кисню на поверхні вугілля (О2.1 та О3.1 тип кисню з Езв. = 533,2-533,7 та 536,8-537,6 еВ, відповідно). Найактивніший зразок, модифікований при температурі 1000ºС, перетворив 57 ммоль H2S/г каталізатора при температурі реакції 180ºС. Зразки V/КАУ синтезовані трьома різними методами (просоченням по вологоємкості та осадженням з водного розчину NH4VO3, а також взаємодією с VO(acac)2 в середовищі ацетонітрилу). Було встановлено, що синтез в органічному середовищі спричиняє утворення нанодисперсних кластерів ванадію на поверхні активного вугілля. Зразки, які містять ванадій, більш активні в порівнянні з термічно модифікованим вугіллям в реакції окиснення H2S при температурі 180ºС. Зразок, синтезований в органічному середовищі, найактивнішій в реакції окиснення сірководню, перетворив більш ніж 132 ммоль H2S/г каталізатора без втрати активності. Покриття поверхні щільним шаром сірки, яка утворюється в результаті реакції, є причиною дезактивації каталізаторів в реакції селективного окиснення H2S.
Методами ДТА, РФЭС, АСМ и титрования по Бёму изучены свойства окисленного активированного угля КАУ, термически модифицированного при различных температурах в инертной атмосфере. Каталитическая активность синтезированных образцов исследована в реакции окисления сероводорода. На поверхности активированного угля установлено присутствие трех типов кислородсодержащих частиц. Показано, что каталитическая активность образцов в окислении сероводорода коррелирует с относительным содержанием ОН-групп и заряженных форм кислорода на поверхности угля (О2.1 и О3.1 тип кислорода с Есв. = 533,2-533,7 и 536,8–537,6 эВ, соответственно). Наиболее активный образец, модифицированный при температуре 1000º С, окислил (превратил) 57 ммоль H2S/г катализатора при температуре реакции 180ºС. Образцы V/КАУ синтезированы тремя различными методами (пропиткой по влагоемкости и осаждением из водного раствора NH4VO3, а также взаимодействием с VO(acac)2 в растворе ацетонитрила). Было установлено, что синтез в органической среде обуславливает образование нанодисперсных кластеров ванадия на поверхности активного угля. Ванадийсодержащие образцы в реакции окисления H2S при температуре 180º С более активны в сравнении с термически модифицированным углем. Образец, синтезированный в органической среде, показал высокую активность в реакции окисления сероводорода, превратив более 132 ммоль H2S/г катализатора без его дезактивации. Покрытие поверхности сплошным слоем образовавшейся серы является причиной дезактивации катализаторов в реакции селективного окисления H2S.
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2079-1704 |
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https://nasplib.isofts.kiev.ua/handle/123456789/29040 |
| citation_txt |
Modification of Activated Carbon KAU Surface Properties / D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal // Хімія, фізика та технологія поверхні. — 2011. — Т. 2, № 1. — С. 41-52. — Бібліогр.: 47 назв. — англ. |
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Хімія, фізика та технологія поверхні. 2011. Т. 2. № 1. С. 41–52
_____________________________________________________________________________________________
* corresponding author zazhigal@ispe.kiev.ua
ХФТП 2011. Т. 2. № 1 41
UDC 544.72
MODIFICATION OF ACTIVATED CARBON KAU
SURFACE PROPERTIES
D.V. Brazhnyk1, I.V. Bacherikova1, V.A. Zazhigalov1*, A. Kowal 2
1 Institute for Sorption and Problems of Endoecology of National Academy of Sciences of Ukraine
13 General Naumov Street, Kyiv 03164, Ukraine
2 Institute of Catalysis and Surface Chemistry of Polish Academy of Sciences
8 Niezapominajek Street, Krakow 30-239, Poland
The properties of oxidized activated carbon KAU treated at different temperatures in inert atmosphere
were studied by means of DTA, Boehm titration, XPS and AFM methods and their catalytic activity in H2S
oxidation was established. Three types of oxygen species exist on carbon catalysts surface. It was shown
that their catalytic activity in hydrogen sulfide oxidation correlated with relative content of OH-groups
and charged oxygen species on carbons surface (O2.1 and O3.1 oxygen types with BE = 533.2–533.7 and
536.8–537.6 eV, respectively). The sample treated at 1000°C has very high activity in H2S oxidation and
transforms up to 57 mmol H2S/g cat at 180°C. The vanadium/carbon KAU samples were prepared by three
different methods (incipient wet impregnation and deposition-precipitation by NH4VO3 in aqueous medium,
and in acetonitrile with VO(acac)2). It was established that synthesis in organic medium led to preparation
of nanodispersed vanadia on carbon surface. The V/C samples were more active in H2S oxidation at 180°C
than treated activated carbons. The sample prepared in organic medium had excellent activity in hydrogen
sulfide oxidation and oxidized more than 132 mmol H2S/g cat without its deactivation. The formation of sur-
face dense sulfur layer is the reason of catalysts deactivation in H2S selective catalytic oxidation.
INTRODUCTION
A currently important aspect of environ-
mental policy is removal of sulfur-containing
species from various gases. Toxicity of sulfur-
containing compounds and their very low odor
threshold determine the development of efficient
desulphurization processes. Governments are
constantly tightening regulations to limit the
emission of sulfur compounds into air and this
makes necessary to enhance the level of sulfur
recovery from natural, refinery, gasification,
cracking, municipal, and other gases.
The most widely used method for H2S re-
moval is Claus process based on reaction of se-
lective transformation of H2S to elemental sulfur
2H2S + SO2 = (3/n)Sn + 2H2O.
The thermodynamic limitations of the Claus
equilibrium reaction fix the maximum hydrogen
sulfide conversion level at about 97%. The devel-
oped Superclaus process permits to reach effi-
ciency up to 99.5%. These processes are very ef-
fective at stable and large sources of raw material
(H2S). Their technological features, advantages
and disadvantages were summarized in reviews
[1, 2].
However, these processes lose their advantages
and efficiency at low H2S content (below 5%) in gas
mixtures or its not-stable source. Adsorption or
catalytic methods use for hydrogen sulfide removal
from a tail gas and the last technology based on di-
rect H2S selective oxidation by air oxygen to ele-
mental sulfur n H2S
+ O2 = n / 2Sn
+ H2O seems
more promising although the catalysts of this re-
action still need to be improved.
Catalysts on the base of metal oxides (bulk or
supported) proposed for direct hydrogen sulfide
selective oxidation at its low concentration [3–10]
and vanadium containing compositions were
among the most promising catalysts. However the
high activity of oxide catalysts leads to formation
of SO2 (dangerous pollutant also) and reduces the
selectivity of the reaction. Sulphatation of the
oxide catalysts or supports provokes decrease of
their activity or destruction.
Carbon containing materials also were pro-
posed as catalysts for the low temperature H2S
oxidation above or below the sulfur dew point
[e.g., 11–19]. It was shown [e.g., 18] that nickel
sulfide supported on high surface area SiC was
active and selective below dew point and oxidized
H2S at low oxygen concentration (O2/H2S
= 2.5)
D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal
_____________________________________________________________________________________________
42 ХФТП 2011. Т. 2. № 1
with sulfur storage of almost 120 wt.%
(1200 mg/g). This catalyst could be regenerated
by sulfur removal at 250–300°C in inert gas (He).
However, an increase of the reaction temperature
or oxygen concentration decreased the oxidation
selectivity and led to SO2 formation. The maxi-
mal values of the sulfur storage on carbon cata-
lysts were obtained at 200°C (690 mg/g) [11].
The unique surface properties of carbona-
ceous materials, such as high surface area and
pore volume, along with their chemical properties
and possibility of their modification make them
very attractive for preparation of catalysts with
better properties in direct selective H2S oxidation
at low reaction temperatures. The most common
ways [e.g., 20–23] for modification of carbon sur-
face are: impregnation with metal salts, controlled
oxidation and thermal treatment of carbons materi-
als. In this study carbon surface was activated by
HNO3 treatment as an effective method of oxy-
gen-containing groups introduction and surface
modification followed by their thermal treatment
in inert atmosphere at different temperatures and
by impregnation with vanadium salts.
Previous study [24] has shown that modifica-
tion of carbon surface by metals (V/C, Mn/C, Fe/C,
Co/C, Cu/C and Mo/C) changes its properties and
increases activity in hydrogen sulphide oxidation,
and that vanadium-containing sample (vanadium
content near 1 wt.%) was the most promising cata-
lyst for this process at low H2S concentration in air.
In this paper the influence of the preparation method
on the properties of the V/C system was studied.
EXPERIMENTAL
Activated carbon KAU prepared from peach
and apricot stones was used as raw material. It
was treated during 4 h in 2M solution of NaOH at
95–100°C washed in water to bring pH of solu-
tion down to 10, treated with hot hydrochloric
acid, washed with water to bring pH of solution
up to 4, then carbonized at 650–700°C and acti-
vated with steam at 800–850°C (KAUin). The
analysis of KAUin sample with Carlo Erba Stru-
mentazione elemental analyzer (mod. 1106)
showed the presence of C (94.3 wt.%),
H (0.5 wt.%) and O (5.2 wt.%). The content of
mineral admixtures was determined by ashing
carbon sample in furnace at 900°C. KAUin sam-
ple contained a smaller quantity of mineral ad-
mixtures (ash content = 0.4 wt.%). The analysis of
ash composition (EDXRS) showed that the base
elements were Ca and Na, and only traces of Al,
Si and Fe were determined. This initial carbon
was oxidized in 25% HNO3 at 95°C during 4 h,
washed with water and dried at 110°C for 4 h
(KAUox). The oxidized activated carbon KAUox
was calcined in argon flow at steadily increasing
temperature (2°C/min) and then the samples were
heated step by step in 2 h at the following tem-
peratures: 400°C (KAU400), 600°C (KAU600),
800°C (KAU800) and 1000°C (KAU1000).
Vanadium-containing catalysts were prepared
by three methods with KAUin as support: i) in-
cipient wet impregnation in water solution with
NH4VO3 (0.69 g of vanadium salt on 30 g of the
support) (Vaq/Ciw), ii) deposition-precipitation in
water solution with NH4VO3 (0.69 g of vanadium
salt on 30 g of the support) (Vaq/Cdp), iii) sup-
port impregnation with OV(C5H7O2)2 (1.56 g of
VO(acac)2 on 30 g of the support) in acetonitrile
medium (Vacac/C). The prepared samples (6 g of
each sample) were dried during 6 h in air at
110°C and calcined in flow of Ar in tubular
quartz reactor (Ø 25 mm and 50 cm in length) at
450°C for 4 h.
The textural characterization of the activated
carbon samples was based on the N2 adsorption
isotherm determined at –196°C with a Quanta-
chrome NOVA/2200e system. Prior to measure-
ment, samples were outgases overnight at 120°C
under nitrogen flow. The pore volumes and pore
size distributions were calculated using density
functional theory. Additionally, the surface areas
and pore volumes were calculated using the BET
and Dubinin–Radushkevich methods.
The surface groups were determined quantita-
tively following the Boehm titration method [25].
Thermal analysis of the samples was realized
with a Derivatograph Q-1500 "F. Paulik, J.
Paulik, L. Erdey" thermoanalytical instrument at
heating rate 5°C/min in air atmosphere.
The amount of vanadium in the catalysts was
measured by atomic absorption spectroscopy and
it was practically equal to 1 wt.% in all samples.
The surface composition of the catalysts was
obtained from XPS spectra recorded by a VG
Scientific ESCA-3 photoelectron spectrometer
using Al Kα1,2 radiation (1486.6 eV). The X-ray
source operated at 13 kV and 10 mA. The work-
ing pressure was lower than 2·10-8 Torr
(1 Torr = 133.3 Pa). All spectra were recorded at
the photoelectron take-off angle of 45º. Binding
energies were referenced to the C 1s peak at
Modification of Activated Carbon KAU Surface Properties
_____________________________________________________________________________________________
ХФТП 2011. Т. 2. № 1 43
284.8 eV from the graphitic peak (maximal inten-
sity). The spectrometer was interfaced with an
IBM PC AT microcomputer for data acquisition
and processing. The data published in [26–32]
were used for the correct identification of ob-
tained results.
The surface morphology of the samples was
studied by atomic force microscopy (AFM) with
a NanoScope E, Digital Instruments Scanning
Probe Microscope Controller.
The catalytic properties of the samples were
determined in reaction of hydrogen sulfide oxida-
tion using a flow type quartz reactor (8 mm di-
ameter and 45 cm in length) with cool flask be-
low reactor. The reaction was performed in tem-
perature range 20–180ºC with the reaction mix-
ture containing 1 vol.% H2S in air (O2/H2S
= 20).
The velocity of the reaction mixture was
50 cc/min and nearly 0.5 g of the catalyst (1 cm3)
was loaded into the catalytic reactor. The content
of hydrogen sulfide in the reactor inlet and outlet
was controlled by GC method and the appearance
of H2S traces (20 ppm) on the catalytic reactor
outlet was additionally qualitatively fixed by
change of color of the filter paper moistened in
1М solution of lead acetate. For the determination
of true catalytic properties of the carbon catalysts
without masked influence of catalytic properties
of sulfur and possible dissolution of H2S in de-
posited sulfur (see above), the activity of carbons
was determined as the quantity of oxidized hy-
drogen sulfide up to first appearance of H2S
traces in catalytic reactor outlet.
RESULTS AND DISCUSSION
DTA method shows that KAUin activated car-
bon sample is stable to oxidation by air up to tem-
peratures of 480–500°C (Fig. 1). Oxidation of this
activated carbon by HNO3 leads to the decrease of
its thermal stability – the surface oxidation of
KAUox begins at temperature of 100–120°C and
burning is observed at 180–200°C. Calcination of
KAUox in inert atmosphere independently on the
treatment temperature increases the thermal sta-
bility of the samples. Data presented in Fig. 1
show that the temperature of mass loss beginning
for the samples KAU600-KAU1000 is not so
much different from the value for KAUinit acti-
vated carbon. The deposition of vanadium on
carbon KAUin surface also increases its tempera-
ture of oxidation beginning up to 300°C for
Vaq/C samples and up to 350°C for Vacac/C
catalyst. These results demonstrate the stability of
the synthesized samples under the reaction condi-
tions used for hydrogen sulfide oxidation.
100
150
200
0 100 200 300 400 500 600
Temperature, 0C
W
ei
g
h
t o
f t
h
e
sa
m
p
le
, m
g
5
2
3
6
4,7
1
Fig. 1. Thermogravimetric data of activated carbons
oxidation by air; 1 – KAUinit, 2 – KAUox, 3 –
KAU600, 4 – KAU1000, 5 – Vaq/Ciw, 6 –
Vaq/Cdp, 7 – Vacac/C)
The characteristic isotherms of nitrogen ad-
sorption obtained on studied samples are pre-
sented in Fig.2.
100
150
200
250
300
350
400
0 0.2 0.4 0.6 0.8 1
Relative pressure, P/P0
V
o
lu
m
e,
c
c/
g
1
2
3
Fig. 2. The isotherms of nitrogen adsorption on
KAUox (1) and V/C samples: Vacac/C (2),
Vaq/Ciw (3)
The presence of type H4 (E in old classifica-
tion) of the hysteresis loop on the isotherms
shows the existence of some mesoporosity in the
samples. The curves of adsorption and desorption
are practically horizontal and parallel in wide
range of relative pressures that can indicate the
preferential microporosity of prepared materials
with slit-shaped pores. The deposition of vana-
dium on carbon surface leads to the shift of the
isotherm downward.
The textural parameters of the preparations
calculated from the isotherms of nitrogen adsorp-
tion are presented in Table 1. The obtained results
show that for all samples the specific surface area
D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal
_____________________________________________________________________________________________
44 ХФТП 2011. Т. 2. № 1
and micropore volume have the practically iden-
tical values. Thus the modification of KAUox
sample by high temperature treatment in an inert
atmosphere and KAUin by vanadium deposition
less influences on this parameters of the sample
porous structure.
Table 1. Textural parameters of the samples calculated
from nitrogen adsorption at -196ºC*
Sample SBET,
m2·g-1
Vtot,
cm3·g-1
Vmіc,
cm3·g-1
R,
nm
E0,
kJ·mol-1
Sex,
m2·g-1
Smic,
m2·g-1
KAUin 1240 0.55 0.52 0.88 – 20.1 1042
KAUox 1150 0.54 0.51 0.94 7.65 4.8 1100
Vaq/Ciw 1140 0.51 0.48 0.89 9.16 1.7 1126
Vaq/Cdp 1130 0.50 0.47 n.d. 9.12 12.6 0.45
Vacac/C 1170 0.54 0.52 0.89 8.97 15.0 1065
*S – specific surface area by BET method, Vmic and E0 –
micropore volume and the characteristic adsorption energy
calculated by DR method, R – average pore width deter-
mined by Dubinin method, Vtot – cumulative pore volume
determined from pores size distribution.
The distribution of the pores for KAUin sam-
ple demonstrates two maxima at the pore radius
equal to 2.4 and 7.0 Å (Fig. 3).
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 1 2 3
Pore radius, nm
d
V
, c
m
3
2
1
4
3
Fig. 3. Pore distribution of sizes for the KAUinit (1),
KAUox (2) and V/C samples: Vaq/Ciw (3),
Vacac/C (4)
Deposition of vanadium on KAUin from wa-
ter and organic solutions results in formation of
samples with different properties. Pore size dis-
tribution for a sample synthesized in non-aqueous
environment practically completely coincides
with initial activated carbon. It testifies that
VO(acac) 2 does not penetrate in micropores and,
most likely, concentrates on an external surface
of the carbon support. This assumption may be
confirmed by V/C atomic ratio calculated from
XPS data (Table 4). Vanadium concentration on
surface of Vacac/C sample is three times higher
than in Vaq/Ciw sample. The porous structure of
the sample Vaq/Ciw well corresponds to those of
the support up to pore sizes of 6 Å but the differ-
ence observes in micro- and mesoporous regions.
This fact can be connected with the penetration of
ammonium vanadate in the big radius pores only.
These data show that the vanadium deposits on
the walls of wide micro- and mesopores of carbon
support and partially fill up them.
The results of Boehm titration presented in
Table 2 suggest that all carbon samples possess
acid (i.e., carboxylic, lactonic and phenolic
groups) and basic functional groups. The amount
of both groups and especially strongly acid
groups (i.e., carboxylic groups) increased after
KAUin sample oxidation. Lactonic groups are
prevalent among acid sites on the KAUox sample
but their content essentially decreased with an
increase of the calcination temperature in inert
atmosphere.
Table 2. The concentration of surface functional
groups in carbons determined by Boehm
titration
Content of surface groups, meq/g
Sample рН carbo-
xylic
lactonic phenolic
total
acidic
total
basic
КАUinit 5.74 0.066 0.38 0.95 1.40 0.3
КАUox 3.78 0.526 1.48 0.49 2.50 1.2
KAU400 5.75 0.432 1.12 0.43 1.98 1.1
КАU600 6.62 0.232 0.37 0.36 0.96 1.0
КАU800 7.78 0.014 0.23 0.15 0.39 0.6
KAU1000 8.88 – 0.06 0.01 0.07 0.3
The data in Table 2 show that the concentra-
tion of the acid groups more decreases than that
of the basic ones and it is accompanied by an in-
crease of the pH of the carbon suspension. After
the sample treatment at 1000°C, the residual
amount of surface acid groups was below the de-
tection limit of the Boehm titration. This result
could be attributed to the higher thermal stability
of the basic surface groups compared to acid
ones. This corresponds to literature data [33]
which show that in lower temperature range
(120–500ºC) strong acid groups (carboxylic
groups) decompose easily than weak acids groups
(phenols and lactonic) and oxygen-containing
organic bases (500–800ºC).
The XPS study of the surface in prepared acti-
vated carbons show the some asymmetry of C 1s
peak. According to literature [26–32], the carbon
Modification of Activated Carbon KAU Surface Properties
_____________________________________________________________________________________________
ХФТП 2011. Т. 2. № 1 45
spectra were well fitted with five peaks which were
assigned to carbon atoms bound with carbon and/or
hydrogen atoms (BE = 284.8 eV, C1.1 peak), to car-
bon atoms with one (C2.1), two (C3.1) and three (C4.1)
bonds with oxygen atoms (BE = 286.2–286.3,
287.7–288.1 and 289.2–290.4 eV, respectively)
and to π–π*peak (C5.1, BE = 291.2–291.8 eV).
The treatment of activated carbon not much influ-
enced the electronic state of carbon atoms and
C1s binding energies. The oxidation of KAUinit
sample slightly decreased the intensity of C1.1 (the
main peak – 60–70% relative intensity of C 1s
peak) and C5.1 peaks and increased the area of the
peaks assigned to carbon-oxygen groups but the
thermal treatment of KAUox carbon in inert at-
mosphere reduced the content of oxygen contain-
ing groups (C2.1–C4.1).
The O 1s spectra of studied carbons were fit-
ted with three peaks and their binding energies
are reported in Table 3.
Тable 3. The binding energy of O 1s-electrons and
relative content of О1s peaks (XPS method)
on samples surface
BE of O 1s-electrons,
eV
Area of О1s peak,
%
Sample*
О1.1 О2.1 О3.1 О1.1 О2.1 О3.1
KAUinit 530.6 533.4 537.1 26.7 58.2 15.1
KAUox 530.6 533.3 536.9 43.8 49.6 6.6
KAU400 531.0 533.7 536.9 41.4 50.0 8.6
KAU600 530.9 533.7 536.8 38.2 50.9 10.9
KAU800 530.8 533.6 537.1 31.5 51.8 16.7
KAU1000 530.4 533.5 537.6 24.3 54.9 20.8
Vaq/Ciw-bc 530.8 533.2 537.5 33.6 56.3 10.1
Vaq/Cdp-bc 530.5 533.6 537.3 34.1 57.2 8.7
Vacac/C-bc 530.1 532.8 536.4 35.5 58.1 6.4
Vaq/Ciw-ac 531.4 533.0 537.1 47.4 47.8 4.8
Vaq/Cdp-ac 531.3 533.2 537.0 49.3 46.7 4.0
Vacac/C-ac 531.6 533.3 537.1 59.6 38.2 2.2
* V/C-bc and V/C-ac – the catalysts before and after
catalytic tests, respectivelly
In agreement with literature [26–29, 31–32]
the O1.1 peak with BE 530.4–531.0 eV was as-
signed to C=O type oxygen (C=O, COOR). The
second peak O2.1 (BE 533.2–533.8 eV) corre-
sponds to C–O type oxygen in C–OH and COOR
groups. Three assignments are possible for the
O3.1 peak with BE 536.8–537.7 eV. According to
published data, it may be due to adsorbed water
or oxygen [26, 28, 32], "charged" oxygen species
[29] or a shake-up peak [27]. The BE near to
539 eV is characteristic for shake-up peak [27].
On other hand, the binding energy of O
1s-electrons of adsorbed water were determined
in the range 535.0–536.0 eV while for adsorbed
oxygen BE = 537.3–537.6 eV were observed
[28, 32]. Therefore, the O3.1 peak may be assigned
to oxygen adsorbed on carbon surface. Taking
into account the possible transfer of π electrons
density from carbon at sorption of hetero-atoms
[34], this oxygen can have an excess of electron
density. The formation of adsorbed superoxide
O2
- on carbon surface with BE > 536.0 eV was
supposed in [35] and in [20] was proposed that π
electrons of carbon could activate oxygen to O2
2-
species which dissociate to O- species.
The relative content of different oxygen spe-
cies (see Table 3) shows that oxidation of KAUinit
with HNO3 increases the O1.1 peak area and de-
creases the area of O2.1 and O3.1 peaks. This corre-
sponds to the increase of the amount of carboxylic
and lactonic groups and to the decrease of the con-
tent of phenolic groups (determined by Boehm
titration – see Table 2). After treating KAUox in
inert atmosphere, the relative content of O1.1 oxy-
gen decreased while the amount of O2.1 and O3.1
species increased (Table 3). The decrease of rela-
tive intensity of the O1.1 peak corresponds to the
moving off of the quantity of carboxylic and lac-
tonic groups (Table 2) and their relative content.
The treatment of the sample in an inert gas at high
temperatures led to formation of unsaturated de-
fects at carbon surface [34]. They can adsorb oxy-
gen with charge transfer causing the increase of
O3.1 peak intensity (Table 3).
The data presented in Fig. 4 demonstrate an
approximately linear correlation between the
amounts of oxygen containing groups (acid
groups) determined by Boehm titration and the
sum of areas of O1.1 and O2.1 XPS peaks.
R2 = 0,8932
0
0,5
1
1,5
2
2,5
78 80 82 84 86 88 90 92 94
Relative area of O1.1+O2.1 peaks
C
o
n
te
n
t
o
f
a
ci
d
g
ro
u
p
s,
m
e
q
/g
Fig. 4. The content of acid groups on activated carbons
determined by Boehm titration vs the relative
area of oxygen containing functional groups
(O1.1+O2.1) from XPS spectra
D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal
_____________________________________________________________________________________________
46 ХФТП 2011. Т. 2. № 1
These results show that XPS data quite well
describe the chemical changes at the surface of
treated activated carbons.
The catalytic activity of the activated carbon
samples in hydrogen sulphide oxidation was de-
fined (see Experimental) as quantity of H2S trans-
formed (with conversion equal to 100%) until the
first appearance of hydrogen sulfide (20 ppm) in
the outlet of reactor. The data obtained (Fig. 5)
show that the reaction temperature strongly influ-
enced the catalytic activity of the carbons.
Fig. 5. The catalytic activity of activated carbons in
oxidation of hydrogen sulfide at different reac-
tion temperatures
Low activity in H2S oxidation at 25°C was
observed for all samples but the treatment in an
inert atmosphere at temperature more than 800°C
little increased the quantity of H2S oxidized. The
more active catalyst KAU1000 oxidizes 160 mg
H2S/g at 25°C. The increase of reaction tempera-
ture up to 100°C slightly influenced the catalytic
activity of the samples. The catalytic activity of
the carbons considerably increased at 180°C. On
the other hand, the activity of the samples in-
creased with increasing temperature of the car-
bons treatment in inert gas (Fig. 5) and KAU1000
at 180°C oxidized 1980 mg H2S/g of catalyst.
This quantity is more than two times higher that
described in literature [12].
The analysis of the gas mixture composition
in the outlet of the reactor did not show the pres-
ence of SO2. The XPS study of the carbons KAU
after catalytic tests showed the presence of one
peak only in the S 2p spectra at 164.0–164.3 eV
which is characteristic of elemental sulfur [36].
Absence of SOx in the reaction products and on
the catalysts surface shows that the reaction of
H2S oxidation under our conditions selectively
proceeds to the formation of elemental sulfur.
Quantity of sulfur formed from the H2S oxidation
at 25°C on KAU1000 catalysts (150 mg Sx/g) is
insufficient to fill fully the volume of pores (at
amorphous sulfur density 1.92 g/cm3 [37] near
20% of volume is filled up) or to form the
monolayer (amount of sulfur is near 3 atom/nm2)
but this amount is capable to cover and deactivate
the surface active centers of the catalyst. Increase
of the reaction temperature up to 180°C gives
more sulfur (1980 mg/g for KAU1000) which
quantity is sufficient to fill pores and cover sur-
face with more than monolayer (34 atom S/nm2).
At this temperature the sulfur partial pressure [37]
is not high enough and only a part of the formed
sulfur desorbs and condensates on cool walls and
flask below the reactor. However, most sulfur re-
mains on the catalyst surface and deactivates its.
The results obtained by us and the data pub-
lished in literature [38–41] allow to suggest that
hydrogen sulfide oxidation proceeds via dissocia-
tive adsorption of H2S with participation of sur-
face OH-groups (O2.1 type) and/or charged oxy-
gen species (O3.1 type). This conclusion agrees
with the data for KAU carbon catalysts in Fig. 6
which shows a good linear correlation between
the amount of hydrogen sulfide oxidized at 100°C
(R2 = 0.97) and 180°C (R2 = 0.93) and the relative
content of O3.1 oxygen species or O2.1 oxygen
type (R2 = 0.95 and R2 = 0.91 at 100 and 180°C,
respectively).
48 52 56
Relative area of O2.1 peak, %
0
1000
2000
H
2S
t
ra
n
sf
or
m
e
d,
m
g
H
2
S
/g
c
at
5 10 15 20 25
Relative area of O3.1 peak, %
Fig. 6. The amount of oxidized hydrogen sulfide at
100°C ( ○) and 180°C ( ● ) vs relative content
of O2.1 type ( ) or O3.1 type (○ ●) of oxygen on
carbon catalysts surface
Therefore, we can conclude that hydrogen
sulfide dissociation on carbon surface can pro-
ceed via following schemes
H2S + CxOH � HS-+ CxOH2;
Modification of Activated Carbon KAU Surface Properties
_____________________________________________________________________________________________
ХФТП 2011. Т. 2. № 1 47
H2S + CxO
σ-
� HS- + CxOH or S2- + CxOH2
and next oxidation on the film of water
HS- + O* � Sads + OH-.
These reactions lead to formation of hy-
droxyl group or adsorbed water and HS- or S2-
ions. The last species can transfer electron(s) to
the carbon surface becoming HS° or S° radicals. It
is known that two HS° or S° radicals can recom-
bine to S2 [42] quickly transformed to Sx [43].
Vanadium deposition on KAU surface less
influences on the shape of O 1s band (Fig. 7) and
the binding energies of the component oxygen
species (Table 3). However, independently on
preparation method the peak area of O1.1 species
increases while the relative content of O2.1 stay
unchangeable and O3.1 oxygen types decreases.
These results can give evidence that oxygen of
the vanadium deposited has the same nature, as
C=O type of carbon support oxygen. Stability of
O2.1 peak area testifies that this form of oxygen
does not participate during deposition of vana-
dium precursor on a carbon surface. The de-
creases of relative content of O3.1 peak in two-
three times in comparison with initial carbon
KAU suggest that vanadium oxides can be
formed on oxygen chemisorption places.
The binding energy of V 2p3/2-electrons is
517.4 eV for all samples independently on the
method of their preparation (Table 4).
Table 4. Surface properties of V/C catalysts before
and after catalytic tests determined by XPS method
Binding
energy, eV
Relative content of
elements, % Sample*
V 2p S 2p C O V S
Atomic
V/C
ratio
KAUox-bc – – 84.0 16.0 – – –
KAUox-ac – 164.2 84.6 14.3 – 1.1 –
Vaq/Ciw-bc 517.4 – 92.4 7.2 0.4 – 0.004
Vaq/Cdp-bc 517.3 – 91.5 8.0 0.5 – 0.005
Vacac/C-bc 517.4 – 89.3 9.4 1.3 – 0.014
Vaq/Ciw-ac 517.4
164.3;
169.0
81.7 16.0 0.7 1.6 0.008
Vaq/Cdp-ac 517.4
164.5;
169.1
81.4 16.1 0.7 1.8 0.009
Vacac/C-ac 517.3
164.6;
169.1
80.4 16.2 0.3 3.1 0.004
* V/C-bc and V/C-ac – the catalysts before and after
catalytic tests, respectivelly
This value points to the presence on carbon
surface of both V5+ and V4+ ions. It is also impor-
tant to note that the surface concentration of va-
nadium for sample prepared in organic medium
(Vacac/C) is three times greater than that in the
case of aqueous preparation used. This fact can be
connected with the different size of initial vana-
dium species in precursor solutions that leads to
difference in structure of vanadium species de-
posited at carbon surface from organic medium
and from water.
a
b
c
Fig. 7. The O 1s spectra (XPS) of activated carbon
KAU and V/C catalysts: a – KAUox , b –
Vaq/Ciw, c – Vacac/C
D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal
_____________________________________________________________________________________________
48 ХФТП 2011. Т. 2. № 1
a
b
c
d
e
Fig. 8. The morphology of V/C catalysts surface (AFM):
a – KAUox, b – Vaq/Cdp-bc, c – Vacac/C-bc, d –
Vaq/Cdp-ac (after 22 h of operation), e – Vacac/C-
ac (after 50 h of tests)
The AFM data confirmed this assumption. It
is necessary to note that amount of deposited va-
nadium (1 wt.%) is 0.1 at.V/nm2 being not suffi-
cient to cover the support surface with
monolayer. As Fig. 8 shows, deposition of vana-
dium from aqueous medium leads to the forma-
tion on carbon surface of thin layer of vanadia
islands. When organic vanadium compound and
organic medium were used in the synthesis,
nanosized vanadia particles were obtained
(Fig. 8c). The direct AFM measurement shows
that these particles have the diameter near 80–
100 nm and the height of 8–10 nm.
Catalytic properties of the V/C catalysts in
hydrogen sulfide oxidation present Fig. 9. As it is
seen the deposition of vanadium on activated car-
bon KAUox less influenced the catalytic activity
at low temperature. Under these conditions, the
amount of H2S transformed on V/C samples is
lower than in the case of KAU1000 catalyst. At
25оС the activity of V/C samples corresponds to
KAU1000 activity that indicates absence of va-
nadium catalytic activity at this temperature.
Fig. 9. The catalytic activity of V/C catalysts in oxida-
tion of hydrogen sulfide as compared with ac-
tivity of activated carbons at different reaction
temperature
At higher temperature of reaction (180°C)
the activity of V/C catalysts exceeds that one ob-
tained on other KAU carbon samples. Excellent
catalytic properties were demonstrated by Va-
cac/C catalyst (see Fig. 9) which transformed
more than 4500 mg H2S/g cat. without the cata-
lyst deactivation (catalytic tests were stopped af-
ter 50 h of continuous work). This result essen-
tially exceeds the data obtained on Vaq/C cata-
lysts prepared in aqueous medium and other
V-containing catalysts prepared by traditional
methods [44]. It worth to note that obtained re-
sults gives no ground to full explanation of the
vanadium-carbon catalysts activity in hydrogen
sulfide oxidation.
Modification of Activated Carbon KAU Surface Properties
_____________________________________________________________________________________________
ХФТП 2011. Т. 2. № 1 49
The AFM study of V/C catalysts surface after
catalytic tests shows (Fig. 8d,e) formation of an
elemental sulfur layer on it. It covers the surface
of samples prepared by traditional method in
aqueous medium (Vaq/C) and it can be the reason
of its deactivation in H2S oxidation. In the case of
Vacac/C sample the formation of sulfur also was
observed but a part of the surface with vanadium
nanoparticles remained free. These uncovered
vanadium particles probable still were active in
hydrogen sulfide oxidation.
The XPS study of V/C samples shows (Ta-
ble 4) that after catalytic tests the binding energy
of V 2p-electrons did not differ from that one in
the initial samples (oxidation state of vanadium
remained unchanged). The surface vanadium con-
tent after catalytic tests in the Vaq/C samples
slightly increased but it decreased by four times
in the Vacac/C catalyst. Simultaneously, the in-
crease of surface oxygen content in relation to
activated carbon after catalytic tests for all V/C
samples was observed independently on the
method of V/C catalyst preparation. Also the shift
of binding energy of O 1s-electrons toward higher
values for the main peak O1.1 type species was
established (Table 3) and it was practically the
same in all preparations. After catalytic tests the
O1.1 peak relative area increased and that ones of
O2.1 and O3.1 decreased (Table 3). However, these
results did not permit to determine the reason of
the high activity of Vacac/C catalyst in hydrogen
sulfide oxidation at 180°C.
In the products of H2S catalytic oxidation on
V/C samples (up to the catalyst deactivation) only
elemental sulfur and water were determined. The
absence of SO2 was verified by chromatographic
analysis and Ba(OH)2 test during catalytic run.
In the same time for all V/C catalysts after
catalytic tests at 180°C the presence of two XPS
peaks in the S 2p-band was found (Table 4). The
first peak at 164.3–164.6 eV is due to elemental
sulfur S0 while the second one at 169.0–169.1 eV
connected with presence of S6+ ions [36]. This
facts can be suggested that =SO2 species are
strongly bonded with the V/C catalysts carbon
surface and did not desorbed at these conditions,
as can be expected for high heat of SOx absorp-
tion (>80 kJ·mol-1) [45].
Thus, the modification of activated carbon
surface by vanadium deposition from organic va-
nadium compound in organic medium leads to
formation of nanosized vanadium on carbon sur-
face which has excellent catalytic activity and
high stability in the hydrogen sulfide oxidation.
All samples of activated carbon modified by va-
nadium contain increased amount of surface oxy-
gen (Table 4) but Vacac/C sample has the maxi-
mal content of the main oxygen peak O1.1 (Ta-
ble 3) which can be connected with the formation
of –V–O species highly reactive in oxidation
analogous to the case of mechanochemical acti-
vated V2O5 [46, 47].
ACKNOWLEDGEMENTS
D.V. Brazhnyk thanks the financial support
from National Academy of Sciences of Ukraine
(grant for young scientists – resolution No 66,
06.04.05).
The work was realized at partial support of
NASU Program (Project No 12, 2006-2010).
REFERENCES
1. Wieckowska J. Catalytic and adsorptive
desulfurization of gases // Catal. Today. –
1995. – V. 24, N 4. – P. 405–465.
2. Pieplu A., Saur O., Lavelley J.C. et al. Claus
Catalysis and H2S Selective Oxidation //
Catal. Rev. Sci. Eng. – 1998. – V. 40, N 4. –
P. 409–450.
3. Marshneva V.I., Mokrinskii V.V. Catalytic
activity of metal oxides in hydrogen sul-
fide oxidation by oxygen and sulfur diox-
ide // Kinet. Catal. – 1989. – V. 29, N 4. –
P. 854–858.
4. Li K.-T., Chien T.-Y. Effect of supports in
hydrogen sulfide oxidation on vanadium-
based catalysts // Catal. Lett. – 1999. – V. 57,
N 1–2. – P. 77–80.
5. Laperdrix E., Costentin G., Saur O. et al. Se-
lective Oxidation of H2S over CuO/Al2O3:
Identification and Role of the Sulfurated Spe-
cies formed on the Catalyst during the Reac-
tion // J. Catal. – 2000. – V. 189, N 1. –
P. 63–69.
6. Park D.-W., Park B.-K., Park D.-K., Woo H-C.
Vanadium-antimony mixed oxide catalysts
for the selective oxidation of H2S contain-
ing excess water and ammonia // Appl.
Catal. A. – 2002. – V. 223, N 1–2. –
P. 215–224.
7. Davydov A.A., Marshneva V.I., She-
potko M.L. Metal oxides in hydrogen sul-
D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal
_____________________________________________________________________________________________
50 ХФТП 2011. Т. 2. № 1
fide oxidation by oxygen and sulfur diox-
ide: I. The comparison study of the cata-
lytic activity. Mechanism of the interac-
tions between H2S and SO2 on some ox-
ides // Appl. Catal. A. – 2003. – V. 244,
N 1. – P. 93–100.
8. Rosso I., Galletti C., Bizzi M. et al. Zinc Ox-
ide Sorbents for the Removal of Hydrogen
Sulfide from Syngas // Ind. Eng. Chem.
Res. – V. 42, N 8. – P. 1688–1697.
9. Lee E.-K., Jung K.-D., Joo O.-S., Shul Y.-G.
Catalytic activity of Mo/MgO catalyst in the
wet oxidation of H2S to sulfur at room tem-
perature // Appl. Catal. A. – 2004. – V. 268,
N 1–2. – P. 83–88.
10. Sánchez J.M., Ruiz E., Otero J. Selective
Removal of Hydrogen Sulfide from Gaseous
Streams Using a Zinc-Based Sorbent // Ind.
Eng. Chem. Res. – 2005. – V. 44, N 2. –
P. 241–249.
11. Steijns M., Mars P. The role of sulfur trapped
in micropores in the catalytic partial oxida-
tion of hydrogen sulfide with oxygen //
J. Catal. – 1974. – V. 35, N 1. – P. 11–17.
12. Steijns M., Mars P. Catalytic Oxidation of
Hydrogen Sulfide. Influence of Pore Struc-
ture and Chemical Composition of Various
Porous Substances // Ind. Eng. Chem.
Prod. Res. Dev. – 1977. – V.16, N 1. –
P.35–41.
13. Richter E. Carbon catalysts for pollution con-
trol // Catal. Today. – 1990. – V. 7, N 2. –
P. 93–112.
14. Choi J.J., Hirai M., Shoda M. Catalytic oxi-
dation of hydrogen sulphide by air over an
activated carbon fibre // Appl. Catal. A. –
1991. – V. 79, N 2. – P. 241–248.
15. Mikhalovsky S.V. Zaitsev Yu.P. Catalytic
properties of activated carbons. I. Gas-phase
oxidation of hydrogen sulphide // Carbon. –
1997. – V. 35, N 9. – P. 1367–1374.
16. Primavera A., Trovarelli A., Primavera A.
et al. The effect of water in the low-
temperature catalytic oxidation of hydrogen
sulfide to sulfur over activated carbon //
Appl. Catal. A. – 1998. – V. 173, N 2. –
P. 185–192.
17. Meeyoo V., Lee J.H., Trimm D.L., Cant N.W.
Hydrogen sulphide emission control by com-
bined adsorption and catalytic combustion //
Catal. Today. – 1998. – V. 44, N 1–4. –
P. 67–72.
18. Keller N., Pham-Huu C., Crouzet C. et al.
Direct oxidation of H2S into S. New cata-
lysts and processes based on SiC support //
Catal. Today. – 1999. – V. 53, N 4. –
P.535–542.
19. Bagreev A., Bandosz T.J. On the Mechanism
of Hydrogen Sulfide Removal from Moist Air
on Catalytic Carbonaceous Adsorbents // Ind.
Eng. Chem. Res. – 2005. – V. 44, N 3. –
P. 530–538.
20. Atamny F., Blöcker J., Dübotzky A. et al. Sur-
face chemistry of carbon: activation of mo-
lecular oxygen // Mol. Phys. – 1992. – V. 76,
N 4. – P. 851–886.
21. Pigamo A., Besson M., Blanc B. et al. Effect
of oxygen functional groups on synthetic car-
bons on liquid phase oxidation of cyclohexa-
none // Carbon. – 2002. – V. 40, N 8. –
P. 1267–1278.
22. Szymaski G.S., Karpiski Z., Biniak S., Swiat-
kowski A. The effect of the gradual thermal
decomposition of surface oxygen species on
the chemical and catalytic properties of oxi-
dized activated carbon // Carbon. – 2002. –
V. 40, N 14. – P. 2627–2639.
23. Strelko V., Malik D.J., Streat M. Characteri-
sation of the surface of oxidised carbon
adsorbents // Carbon. – 2002. – V. 40, N 1. –
P. 95–104.
24. Zazhigalov V.A., Brazhnyk D.V., Zait-
sev Yu.P. et al. Activity of Me/carbon
supported catalysts in H2S oxidation //
CarboCat: Abstracts of I International
Symposium on Carbon for Catalysis (June,
2004, Lausanne, Switzerland). – P. 182.
25. Boehm H.P. Chemical identification of sur-
face groups // Advances in Catalysis / Eds.
D.D. Eley, H. Pines, P.B. Weisz. – New
York: Academic Press, 1966. – V. 16. –
P. 179–274.
26. Proctor A., Sherwood P.M.A. X-ray photo-
electron spectroscopic studies of carbon fibre
surfaces. I. carbon fibre spectra and the ef-
fects of heat treatment // J. Electron Spec-
trosc. Relat. Phenom. – 1982. – V. 27, N 1. –
P. 39–56.
27. Gardella J.A. Ferguson S.A., Chin R.L.
π*←π Shakeup Satellites for the Analysis of
Structure and Bonding in Aromatic Polymers
by X-Ray Photoelectron Spectroscopy //
Appl. Spectrosc. – 1986. – V. 40, N 2. –
P. 224–232.
Modification of Activated Carbon KAU Surface Properties
_____________________________________________________________________________________________
ХФТП 2011. Т. 2. № 1 51
28. Xie Y., Sherwood P.M.A. X-ray photoelec-
tron-spectroscopic studies of carbon fiber sur-
faces. 11. Differences in the surface chemis-
try and bulk structure of different carbon fi-
bers based on poly(acrylonitrile) and pitch
and comparison with various graphite sam-
ples // Chem. Mater. – 1990. – V. 2, N 3. –
P. 293–299.
29. Paal Z., Schlogl R., Ertl G. The surface state
and catalytic properties of Pt black after O2-
H2 cycles // Catal. Lett. – 1992. – V. 12,
N 2. – P. 331–344.
30. Albers P., Deller K., Despeyroux B.M. et al.
SIMS/XPS Investigations on Activated Car-
bon Catalyst Supports // J. Catal. – 1994. –
V. 150, N 2. – P. 368–375.
31. Darmsadt H. Roy C., Kaliaguine S. ESCA
characterization of commercial carbon blacks
and of carbon blacks from vacuum pyrolysis
of used tires // Carbon. – 1994. – V. 32,
N 8. – P. 1399–1406.
32. Burg P., Fydrych P., Cagniant D. et al. The
characterization of nitrogen-enriched acti-
vated carbons by IR, XPS and LSER meth-
ods // Carbon. – 2002. – V. 40, N 9. –
P. 1521–1531.
33. Papirer E., Dentzer J., Li Sh., Donnet J.B.
Surface groups on nitric acid oxidized carbon
black samples determined by chemical and
thermodesorption analyses // Carbon. –
1991. – V. 29, N 1. – P. 69–72.
34. Bradley R.H., Daley R., Le Goff F. Polar and
dispersion interactions at carbon surfaces:
further development of the XPS-based
model // Carbon. – 2002. – V. 40, N 8. –
P. 1173–1179.
35. Stöhr B., Boehm H.P., Schlögl R. Enhance-
ment of the catalytic activity of activated car-
bons in oxidation reactions by thermal treat-
ment with ammonia or hydrogen cyanide and
observation of a superoxide species as a pos-
sible intermediate // Carbon. – 1991. – V. 29,
N 6. – P. 707–720.
36. Moulder J.F., Stickle W.F., Sobol P.E., Bom-
ben K.D. Handbook of X-Ray photoelectron
spectroscopy. – Minnesota: Perkin-Elmer
Corp., 1992.
37. Schwefel W. Gmelins Handbuch der Anorga-
nishen Chemie. – 8th ed. – Weinheim: Verlag
Chemie, 1953. – 762 S.
38. Lin M.J., Lunsford J.H. An electron para-
magnetic resonance study of the hydrogen
sulfide (H2S2-) radical on magnesium ox-
ide // J. Phys. Chem. – 1976. – V. 80, N 18. –
P. 2015–2018.
39. Karge H.G., Raskó J. Hydrogen sulfide
adsorption on faujasite-type zeolites with
systematically varied Si-Al ratios // J. Col-
loid Interface Sci. – 1978. – V. 64, N 3. –
P. 522–532.
40. Liu C.L., Chuang T.T., Dalla Lana I.G.
The oxidizing properties of γ-alumina: In-
frared studies of the adsorption of H2S and
CS2 // J. Catal. – 1972. – V. 26, N 3. –
P. 474–476.
41. Karge H.G., Laniecki M., Zioek M. UV-
visible spectroscopic investigations of the
modified claus reaction on NaX zeolite cata-
lysts // J. Catal. – 1988. – V. 109, N 2. –
P. 252–262.
42. Clark P.D., Dowling N.I., Huang M. Pro-
duction of H2 from catalytic partial oxida-
tion of H2S in a short-contact-time reac-
tor // Catal. Comm. – 2004. – V. 5, N 12. –
P. 743–747.
43. Davis P.R., Bechtold E., Block J.H. Sulfur
surface layers on tungsten investigated by
field ion mass spectroscopy // Surf. Sci. –
1974. – V. 45, N 2. – P. 585–600.
44. Lee E.-K., Jung K.-D., Joo O.-S. Shul Y.-G.
Redox behavior of V/MgO catalyst in H2S
wet oxidation at room temperature // React.
Kinet. Catal. Lett. – 2004. – V. 83, N 1. –
P. 25–30.
45. Anurov S.A. Physical-chemical aspects of
sulfure dioxide adsorption by carbon sor-
bents // Uspekhi Khimii. – 1996. – V. 65,
N 8. – P. 718–732 (in Russian).
46. Zazhigalov V.A., Haber J., Stoch J. et al.
Influence of the mechanochemical treatment
on the reactivity of V-containing oxide
systems // Solid State Ionics. – 1997. –
V. 101–103, N 2. – P. 1257–1262.
47. Su D.S., Roddatis V., Willinger M. et al.
Tribochemical Modification of the
Microstructure of V2O5 // Catal. Lett. –
2001. – V. 74, N 3–4. – P. 169–175.
Received 26.01.2011, accepted 01.02.2011
D.V. Brazhnyk, I.V. Bacherikova, V.A. Zazhigalov, A. Kowal
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52 ХФТП 2011. Т. 2. № 1
Mодификація властивостей поверхні активованого вугілля КАУ
Д.В. Бражник, І.В. Бачерикова, В.О. Зажигалов, А. Коваль
Інститут сорбції та проблем ендоекології Національної академії наук України
вул. Генерала Наумова 13, Київ 03164, Україна
Інститут каталізу та фізико-хімії поверхні Польської академії наук,
вул. Незапоминаек 8, Краків 30-239, Польща
Методами ДТА, РФЕС, АСМ та титрування за Бьомом вивчені властивості окисленого активованого вугілля
КАУ, термічно модифікованого при різних температурах в інертному середовищі. Каталітична активність
синтезованих зразків досліджена в реакції окиснення H2S. На поверхні активованого вугілля встановлено при-
сутність трьох типів кисневмісних частинок. Показано, що каталітична активність зразків в окисненні сір-
ководню корелює з відносним вмістом ОН-груп та заряджених форм кисню на поверхні вугілля (О2.1 та О3.1 тип
кисню з Езв. = 533,2-533,7 та 536,8-537,6 еВ, відповідно). Найактивніший зразок, модифікований при темпера-
турі 1000ºС, перетворив 57 ммоль H2S/г каталізатора при температурі реакції 180ºС. Зразки V/КАУ синтезо-
вані трьома різними методами (просоченням по вологоємкості та осадженням з водного розчину NH4VO3, а
також взаємодією с VO(acac)2 в середовищі ацетонітрилу). Було встановлено, що синтез в органічному сере-
довищі спричиняє утворення нанодисперсних кластерів ванадію на поверхні активного вугілля. Зразки, які міс-
тять ванадій, більш активні в порівнянні з термічно модифікованим вугіллям в реакції окиснення H2S при тем-
пературі 180ºС. Зразок, синтезований в органічному середовищі, найактивнішій в реакції окиснення сірковод-
ню, перетворив більш ніж 132 ммоль H2S/г каталізатора без втрати активності. Покриття поверхні щіль-
ним шаром сірки, яка утворюється в результаті реакції, є причиною дезактивації каталізаторів в реакції се-
лективного окиснення H2S.
Модификация свойств поверхности активированного угля КАУ
Д.В. Бражник, И.В. Бачерикова, В.А. Зажигалов, А. Коваль
Институт сорбции и проблем эндоэкологии Национальной академии наук Украины
ул. Генерала Наумова 13, Киев 03164, Украина
Институт катализа и физико-химии поверхности Польской академии наук
ул. Незапоминаек 8, Краков 30-239, Польша
Методами ДТА, РФЭС, АСМ и титрования по Бёму изучены свойства окисленного активированного угля
КАУ, термически модифицированного при различных температурах в инертной атмосфере. Каталитиче-
ская активность синтезированных образцов исследована в реакции окисления сероводорода. На поверхно-
сти активированного угля установлено присутствие трех типов кислородсодержащих частиц. Показано,
что каталитическая активность образцов в окислении сероводорода коррелирует с относительным со-
держанием ОН-групп и заряженных форм кислорода на поверхности угля (О2.1 и О3.1 тип кислорода с Есв. =
533,2-533,7 и 536,8–537,6 эВ, соответственно). Наиболее активный образец, модифицированный при тем-
пературе 1000ºС, окислил (превратил) 57 ммоль H2S/г катализатора при температуре реакции 180ºС. Об-
разцы V/КАУ синтезированы тремя различными методами (пропиткой по влагоемкости и осаждением из
водного раствора NH4VO3, а также взаимодействием с VO(acac)2 в растворе ацетонитрила). Было уста-
новлено, что синтез в органической среде обуславливает образование нанодисперсных кластеров ванадия на
поверхности активного угля. Ванадийсодержащие образцы в реакции окисления H2S при температуре 180ºС
более активны в сравнении с термически модифицированным углем. Образец, синтезированный в органиче-
ской среде, показал высокую активность в реакции окисления сероводорода, превратив более 132 ммоль
H2S/г катализатора без его дезактивации. Покрытие поверхности сплошным слоем образовавшейся серы
является причиной дезактивации катализаторов в реакции селективного окисления H2S.
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