Dr. SÁRKÁNY, JÁNOS
senior researcher
PERSONAL INFORMATIONS:
Name, family name: Dr.
János Sárkány, C.Sc. (Candidate of Science, Chemistry)
Date of Birth:
Place of Birth:
Office Address: Department
of Organic Chemistry,
(before
2000:
Dóm
tér 8, H-6720 Szeged, Hungary
Phone:
+36 (country) 62 (city) 544-511
Fax: (+36)-62-544-200
E-mail: sarkany@chem.u-szeged.hu
Home page: http://www.staff.u-szeged.hu/~sarkany
EDUCATION:
C.Sc. (Candidate of Science): 1990, chemistry,
Hungarian
Dissertation: "Using adsorption features to study
catalysts and catalytic reactions"
Ph.D. (in Chemistry): 1977,
Dissertation: "Formation and reaction of surface
isocyanate on alumina-supported Pt, Pd and Rh catalysts"
(supervisor:
Prof. Frigyes Solymosi)
M.Sc. (in Chemistry): 1973,
chemistry,
Dissertation: "Effect of additives on the burning rate
of the mixtures of ammonium perchlorate, metal and polystyrene"
(supervisor:
Prof. Frigyes Solymosi)
Student: 1968-1973,
chemistry,
[1969-1973, resident in Eötvös Loránd Kollégium
(Residence Hall) of
Compulsory service: 1967-1968,
military service at Gábor Áron Tank Unit,
Secondary Shcool: 1963-1967,
Nagy Lajos Grammar-School (special chemical-physical classes),
Pécs,
POSITIONS:
1991- to day senior research worker, Department of
Organic Chemistry,
1985-1991 research worker, Department of Organic
Chemistry,
1977-1984 research assistant,
Department of Organic Chemistry,
1973-1977 research assistant, Reaction Kinetics
Research Group,
FELLOWSHIPS:
visiting research scientist: 1992-1993 (1 year),
Sinclair Laboratory,
Department
of Chemistry,
(supervisor:
Prof. Kamil Klier)
visiting research scientist: 1992 (3 months), Sinclair
Laboratory,
Department
of Chemistry,
(supervisor:
Dr. Robert P. Eischens)
visiting research scientist: 1991-1992 (1 year), V.N.
Ipatieff Laboratory, Center for Catalysis and Surface
Science,
Department of Chemistry, Northwestern University,
(supervisor:
Prof. Wolfgang M. H. Sachtler)
postdoctoral fellow: 1980-1982
(1.5 years), Department of Chemistry,
(supervisor:
Prof. Richard D. Gonzalez)
postdoctoral fellow: 1978-1979
(3 months), Institute of Isotopes, Hungarian
(supervisor:
Prof. László Guczi)
MEMBERSHIPS IN PROFESSIONAL SOCIETIES:
Hungarian
Chemical Society
Catalysis
Club of the
TEACHING EXPERIENCE:
Organic Chemistry: practice
for chemical and pharmaceutical students (from 1982)
Organic Chemistry (in
English): practice for pharmaceutical students (1995-1997)
Basic Chemistry: practice
for chemical students (1990)
Special Course: lecture
"IR spectroscopy in catalysis" for chemical students (from 1995)
HONORS AND AWARDS:
1983 Presidential
Academic Award for research
●
Hungarian
1996 Best
Practical Teacher award
●
1997 Best
Practical Teacher award
●
2004 Great Minds of the 21st Century -
inclusion
●
American Biographical Institute, Inc. (
2004 2000
Outstanding Scientist of the 21st Century (with Honours List) - inclusion
●
International Biographical Centre (
2004 Universal
Award of Accomplishment
●
American Biographical Institute, Inc. (
2004 International
Scientist of the Year 2004
●
International Biographical Centre (
2004 Citation
of Meritorious Achivement
●
International Biographical Centre (
2004 International
Order of Merit (membership for life, right to use the letters IOM after my
name)
●
International Biographical Centre (
2004 Honorary
Member of the Research Board of Advisors - International Division
●
American Biographical Institute, Inc. (
2004 Outstanding
Professional Award (for Achievements in Chemistry)
●
American Biographical Institute, Inc. (
2004 Key
Award (Achievement in Research Award)
●
American Biographical Institute, Inc. (
2004 Hall
of Fame
●
International Biographical Centre (
2004 Lifetime
Achievement Award
●
International Biographical Centre (
2004-2005 Leading
Intellectuals of the World (The Genious Elite) - inclusion
●
American Biographical Institute, Inc. (
CITATION NUMBER (by Science Citation Index, SCI) up to
for
all publications appeared up to 2004.
RESEARCH:
All
of my scientific publications can be seen under Publications All.
Research in detail:
(A)
BEFORE DIPLOMA (1970-1973): (a)
Effects of oxide catalysts and Al metal on the burning rate of the mixture of
ammonium perchlorate + polystyrene (AP + PS) in N2 atmosphere. (b) High-temperature catalytic
decomposition (explosion) of AP + PS, effect of additives. (c) Catalytic decomposition of perchloric acid.
(B) AFTER
DIPLOMA (from M.Sc., 1973-):
(1) Development of new methods. (a) A new, alternative method to
estimate metal (for example supported
Pt) surface areas based solely on either eluted H2 or CO peak hights
was developed. The fraction of H2 and CO reversibily adsorbed was
determined from the peak heights of the eluted pulses. For Pt-SiO2 and Pt-Al2O3, 13%
of the H2 and 4.4% of the adsorbed CO were found to be reversibly
adsorbed. (b) For the IR spectra
obtained in transmittance by simple analog spectrophotometers having no
built-in possibilities to convert electronically the spectra to absorbance
scale, a novel evaluation method was elaborated to determine band position
based on a specially modified base line. This approaching procedure was mostly
useful for weak and broad bands with sloping base line. (c) The extinction coefficients of CO linearly adsorbed on
different Pt-SiO2 catalysts were measured at various temperatures as
a function of CO coverage using a new GC-IR combined pulse method. (d) The oxidation (ionic) state of
copper introduced into ZSM-5 by ion-exchange was monitored by FT-IR technique
based on that finding that the local perturbation-caused shift of the internal
antisymmetric T-O-T stretching vibration depends on the effective charge
towards the framework of the copper species being inside the zeolitic channels.
Hence, the complexation of copper (or other guest) cation turned to be an
important factor as well. (Publications
1.)
(2) Formation, stability and
reactivity of surface -NCO related to NO + CO ® N2 + CO2 reaction. Noble
metal-based supported catalysts used for NOx abatement in the
reaction NO + CO ® N2 + CO2 produce surface -NCO
complex, too. IR spectroscopy, combined IR-MS technique and gravimetric
adsorption method (electronic vacuum microbalance) were used to study the
formation, stability and reactivity of surface -NCO on supported Pt, Pd and Rh
catalysts. The migration of surface -NCO
species from the metal to support was found for SiO2-, Al2O3-,
MgO- and TiO2-supported Pt. The reaction of surface -NCO with NO, O2,
H2 and H2O was also investigated. The reaction of -NCO
with H2O or H2 resulted in, among others, gaseous NH3.
(Publications 2.)
(3) Adsorption-desorption
hysteresis of CO, features of CO(A), CO(D), production of CO IR doublet,
CO(DA), on Pt/SiO2. On an adsorption-thermal desorption cycle,
the frequency of the stretching
vibration of CO, n(CO), adsorbed on Pt-SiO2, for
example, varied according to a hysteresis. In the case of lower CO coverages, QCOs,
two types of adsorbed CO [called CO(A) and CO(D)] could be produced (a) by CO
adsorption on an empty Pt surface at 298 K or (b) by partial desorption of a
CO-covered Pt surface. Since at QCO » 0.35 n[CO(A)] = 2070 and n[CO(D)] = 2047 cm-1 were found, thus
the combination of these two bands, i.e.,
a CO IR doublet [denoted as CO(DA)], was also producable. The features of
CO(A), CO(D) and CO(DA), their interactions (reactions) with different gases
and the role of Pt surface were studied in detail. The adsorption of CO in
islands was indirectly improved for CO(A), while the opposite tendency was true
for CO(D). The properties of CO(DA) basically derived from the features of
CO(A) and CO(D). (Publications 3.)
(4) CO indication method:
coadsorption of CO and oxa- and dioxacycloalkanes on Pt-SiO2. The value of n(CO) of the linearly preadsorbed CO on Pt-SiO2
depended very much on the electron donation ability of the after-adsorbed Lewis
base (LB). This observation was the basis of the so-called CO-indication method
when the adsorption of LB on supported Pt could be indirectly studied. [Unlike
CO, LBs are also adsorbed on SiO2 of high surface area (200-250 m2
g-1) which makes difficult the direct study of their
adsorption on supported Pt.] For a series of oxa- and dioxacikloalkanes, the first
ionization potential (IP), the molecular structure and the adsorbed form proved
to be fundamental to interpret the obtained Dn(CO) shifts. At low QLB values, local dipolar decouplings between the CO
molecules were suggested on the basis of the changes in the intensity and shape
of the CO(A) band. In the case of CO(D) + LB, the much higher red shifts in n(CO) supported the much lower QCO(local)
for CO(D) compared to that for CO(A). (Publications 4.)
(5) Interaction between Lewis
bases and surface OH groups of SiO2. Transmission
IR spectroscopy revealed strong H-bonds between Lewis bases (diethyl ether and
various oxa- and dioxacycloalkanes) containing one or two sp3 hybridized
O atoms and the surface OH groups of Cab-O-Sil. The n(OH) band shifted by 385-520 cm-1 to
the lower wavenumbers while the intensity and the half-width significantly
increased, depending on the adsorbate. The results were explained on the basis
of charge-transfer theory from which the sequence of electron-donating ability
was also established for the LBs examined. (Publications 5.)
(6) NO adsorption on variously
pretreated Pt-SiO2 catalysts, occurrence of band-collapse. Like CO,
NO is strongly chemisorbed on supported Pt. Transmission IR spectrometry was
used to study NO adsorption at 298 K on variously pretreated Pt-SiO2
samples. Three distinct NO species were proposed: linearly adsorbed NO
(1770-1800 cm-1), NO(l), bridge-bonded NO (1570-1600 cm-1),
NO(b), and vibrationally coupled NO, NO(vc). The IR spectra depended very much
on the surface structure rather than on Pt dispersion. For a freshly reduced 5
wt% Pt-SiO2, only NO(l) and NO(b) were obtained, and the intensities
of the related bands gradually increased with increasing NO surface coverage.
On the contrary, the "collapse" of band NO(l) was found at higher QNO
for a used catalyst or a sample with prolonged treatment in H2 at
673 K, promoting with this the formation of vibrationally coupled NO. On the
other hand, a sustained treatment in O2 at 673 K hindered the
collapse of band NO(l), i.e., the
propagation of NO(vc) species. On the experiments (preadsorbed NO + CO) and
(preadsorbed CO + NO), the variations of NO(l)/NO(b) ratio and n[NO(l)] with increasing QCO
and QNO,
respectively, showed dose sequence-dependent features. (Publications 6.)
(7) Characterizations of SiO2-
and Al2O3-supported Pt and Pt-Sn catalysts; support and dispersion
effect, migration of Pt from SiO2 to Al2O3, interaction between Pt and Sn, test
reactions. Prior to the reduction in H2
stream, the effect of initial pretreatment on Pt dispersion was more pronounced
for the Al2O3-supported Pt catalysts than for the SiO2-supported
ones. When Pt-SiO2 or Pt-Al2O3 catalysts were
diluted with either pure Al2O3 or SiO2
previuos to pretreatment, extensive interparticle diffusion of Pt precursor
occurred. The interparticle transfer of Pt from SiO2 to Al2O3
during pretreatment for a series of
Pt-SiO2 : Al2O3 mixtures was studied by
both selective (CO and H2) chemisorption and IR spectroscopy. In
addition to the lower CO/H ratios for chemisorption, the presence of bridged
CO, CO(b), at around 1825-1830 cm-1 and the more complex spectra for
linearly adsorbed CO species, CO(l), in the range 2100-2000 cm-1
suggested that the structures of Pt particles on Al2O3
were different from those on SiO2. For the test reaction CO + H2
® CH4 + H2O the Pt-Al2O3,
while for the reaction CO + O2 ® CO2 the Pt-SiO2 catalysts
showed higher turnover frequencies. The variation of Pt dispersion resulted in
much smaller effect on both the catalytic reduction and oxidation of CO than
the change of support did. IR spectroscopy uncovered a greater reactivity of
CO(b) species with O2 relative to that of CO(l) forms, in accordance
with the higher activities obtained for the catalysts with larger Pt particles
characterized by higher CO(b)/CO(l) ratios. Interaction between Sn and Pt
supported on Al2O3 depended on the metal loading and the
surface area of Al2O3. For the SiO2-supported
catalysts, the Sn-Pt interaction started at much lower metal loadings,
according to the IR results observed for the adsorption of
(8) Ethane-deuterium exchange on
various Pt catalysts. The study of ethane-deuterium exchange on
different Pt-silica gel and Pt-Cab-O-Sil catalysts revealed that the rate of
H-D exchange depended on the type of SiO2 support used, but did not
depend on the Pt dispersion. Therefore, the H-D exchange on Pt-SiO2
for ethane might be classified as demanding and structure-insensitive reaction.
(Publications 8.)
(9) Catalytic oxidative coupling
of CH4 on modified SrO-La2O3 catalysts. While CH4
is an excellent gaseous fuel, it is desirable to convert it via 1-step process
to higher molecular weight products for transportation, storage and utilization
as chemical feedstocks. Many substances were scrutinized in this respect in
several laboratories. Among others, SrO-La2O3 catalyst
has been reported to be active in the formation of methyl radicals and
therefore of C2 hydrocarbons. Acid doping of the strongly basic 1
wt% SrO-La2O3 catalyst with sulfate promoted both the
conversion and selectivity in the oxidative coupling of CH4 to C2
hydrocarbons (C2H6, C2H4). The
sulfate content was optimized to get the largest promotional effect. The CH4
conversion and C2 selectivity varied in a close relationship. (Publications 9.)
(10) Redox chemistry of
over-exchanged Cu-ZSM-5. The catalytic reduction of NOx is
still a big challenge because new, possibly non-noble metal-based catalysts should
be developed for the lean-burn engines. Over-ionexchanged Cu-ZSM-5 proved to be
one of the most promising catalyst in the low temperature catalytic
decomposition of NO to N2 and O2. Thus, the basic study
of the redox chemistry of this type of catalyst is significant to get a better
view for the mechanism of catalytic NOx abatement. FT-IR
spectroscopy was a useful technique in this work. It was demonstrated that the
internal asymmetric stretching vibration, ν(int,as)(TOT), of the ZSM-5 (nSi/nAl
= 20, nCu/nAl = 0.75) framework depended on the charge of
the intrazeolitic copper ion, and its complexation with extraframework
ligand(s). The effect was attributed to a guest cation-caused local skeletal
perturbation. On the reduction of copper ions to Cuo atoms by H2,
for example, this perturbation disappeared, along with the formation of
zeolitic OH groups. The reverse process, i.e.,
the H+-assisted reoxidation of Cuo atoms to ionic species
could be monitored as well. Similarly, the autoreduction of CuII-oxo
species to isolated Cu+ ions in Ar (of which degree strongly
depended on the amount of water in the Ar stream) or the interactions of Cu+
ions with O2 could also be followed in this way. (Publications 10.)
(11) CO-TPR-like FT-IR study of
over-exchanged, O2-calcined CuII-ZSM-5.
Over-exchanged, O2-calcined CuII-ZSM-5 (nSi/nAl
= 20, nCu/nAl = 0.75) was treated with flowing CO/He
mixture, with stepwise increases of the temperature from 293 to 773 K. The
(partial) reduction was followed by the changes in the spectral features of
intrazeolitic Cu+ mono- and di-carbonyls and skeletal vibrations of
ZSM-5, related mainly to different ν(CO) and (locally easily perturbable)
ν(int,as)(TOT) bands. Evaluation of temperature-dependent changes in the
integrated band intensities (BCO)
and some other features of the different Cu+-carbonyls resulted in
more significant inferences. Three main sections could be distinguished in the
formation of carbonyls. Along with the ν(12CO) carbonyl bands,
relevant ν(13CO) side bands were also obtained due to the ca.
1.11 % 13C content in the nature. The presence of water
significantly decreased the adsorbed amount of CO at 293 K which could not be
attributed to displacement of CO(ads) by H2O, but certain
(undesirable) surface reaction(s) of copper species with water. (Publications 11.)
(12) Effect of water and
ion-exchanged counterion on the FT-IR spectra of ZSM-5 [along with H-bonding with OH groups of zeolite,
formation of H+(H2O)n]. Depending on the amount, H2O
markedly influenced almost the whole FT-IR spectra of NaH-ZSM-5 and [Cu+(CO)n]-ZSM-5
(nSi/nAl = 20, nCu/nAl = 0.75).
Three main processes could be distinguished: (i) physical adsorption of H2O,
(ii) coordination of Na+ ion or Cu+-CO by H2O
and (iii) interaction of (remainder) zeolitic OH groups with H2O
molecules resulting in strongly H-bonded interactions (with Fermi resonance at
certain conditions) or/and protonated water, H+(H2O)n.
At high H2O concentration, the H2O ligands in the
aquacomplex completely screened the positive charge of Na+ or Cu+
(in Cu+-CO) ions, disappearing with this for a short time the local
perturbation of the internal (T-O-T) antisymmetric stretching lattice
vibration. In the case of [Cu+(CO)2]-ZSM-5, the second CO
ligand was easily displaced with H2O at 293 K, on the contrary to
the first CO ligand. (Publications
12.)
(13) NO adsorption on
over-exchanged Cu-ZSM-5 using FT-IR spectroscopy. Partly in
accordance with others, "NO adsorption" proved to be quite complex
due to the possible surface processes based on the available species in an O2-calcined,
over-exchanged CuII-ZSM-5 (nSi/nAl = 20, nCu/nAl
= 0.75) sample. In addition, some changes in the FT-IR spectra revealed more or
less time-dependency, too, related to alterations in the surface species. (Publications 13.)
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