02717nas a2200301   4500008004100000022001400041245010700055210006900162260007300231300001200304490000800316520171400324653001202038653001802050653002302068653001002091653000702101653001302108653002002121653001802141653002302159100001802182700001602200700002802216700001802244700003002262856012302292       2005                        eng d  a1381-116900aInsight into the mechanism of selective mono-N-methylation of aniline on Cu1-xZnxFe2O4: a DRIFTS study0 aInsight into the mechanism of selective monoNmethylation of anil  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR  a169-1800 v2313 a<p>Mechanism of selective mono-N-methylation of aniline with methanol on Cu1-xZn2FeO4 catalysts was investigated in detail. The interaction of reactants (aniline. methanol and methanol: aniline) and possible products (N-methylaniline (NMA), N,N-dimethylaniline (DMA) and o-toluidine (OT)) on catalysts surface was studied by temperature-dependent in situ FTIR spectroscopy. Methanol adsorbs dissociatively over catalysts surface at 373 K as methoxy species and is oxidized to formate species at high temperature through dioxymethylene and/or formaldehyde as a surface intermediate species. On the other hand, adsorption of aniline:methanol mixtures shows that methanol oxidation was completely hindered in the presence of aniline. Aniline adsorbs on the Lewis acid sites at &lt;= 373 K with phenyl ring oriented in a perpendicular manner to the catalyst surfaced however, N-H bond scission occurs above 373 K. A comparison of adsorbed NMA and methanol: am line (3:1) mixture on Cu0.5Zn0.5Fe2O4 shows NMA forms from the reaction mixture at 473 K. However, maximum activity at 573 K in catalytic reaction studies suggests that desorption limits the methylation kinetics. FTIR study displays stable aniline and methyl species on ZnFe2O4 even at 573 K; however. no methyl species is detected on Cr0.95Zn0.05Fe2O4 at 473 K due to methanol reforming reaction and that limits the overall reaction and hence low catalytic activity. It is proposed that methanol is protonated on catalysts surface by the labile H+ due to N-H bond scission. Co-adsorption of acidity probes with aniline and methanol indicates that aniline methylation takes place at single acid-base site. (c) 2005 Elsevier B.V. All rights reserved.</p>10aAniline10aCu1-xZnxFe2O410adesorption limited10aDRIFT10aIR10aMethanol10aN-methylaniline10aN-methylation10areaction mechanism1 aVijayaraj, M.1 aMurugan, B.1 aUmbarkar, Shubhangi, B.1 aHegde, S., G.1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/insight-mechanism-selective-mono-n-methylation-aniline-cu1-xznxfe2o4-drifts-study-002227nas a2200265   4500008004100000022001400041245014400055210006900199260009500268300001000363490000800373520126800381653001201649653001201661653002001673653001801693653001101711653001501722653002501737653000801762653000801770100002401778700003001802856012901832       2006                        eng d  a0021-951700aOn the ``Active spacer and stabilizer'' role of Zn in Cu1-xZnxFe2O4 in the selective mono-N-methylation of aniline: XPS and catalysis study0 aActive spacer and stabilizer role of Zn in Cu1xZnxFe2O4 in the s  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcJUL  a83-950 v2413 a<p>A systematic catalytic methylation study on ferrospinel materials led to the selective production of N-methylaniline (NMA) with Cu1-xZnxFe2O4. Aniline methylation was carried out on Cu1-xZnxFe2O4 with a feed composition of CH3OH:PhNH2:H2O = 3:1:1 at 513-633 K. NMA was formed selectively on all of the catalyst compositions, with trace amounts of secondary products under most of the conditions. Cu0.5Zn0.5Fe2O4 composition showed high catalytic activity and stability up to 100 h. Although the Cu2+ was responsible for methylation activity, Zn2+ enhanced the overall stability of the catalyst system. XPS investigations revealed that the degree of Cu2+ reduction decreased dramatically from x = 0.05/0.25 to 0.5/0.75 on spent catalysts. TPR studies indicated that the reducibility of Cu2+ decreased from fully reducible at 523 K with Cu-rich compositions to partially reducible at 573 K on x = 0.5. Stable activity observed on Cu0.5Zn0.5Fe2O4 can be attributed to the highly heterogeneous distribution of metal ions. This heterogeneous distribution indicates an important role of zinc, likely as an ``active spacer cum stabilizee' that hinders the reduction of active Cu2+ and contributes to prolonged activity. (c) 2006 Elsevier Inc. All rights reserved.</p>10aAniline10aFerrite10aN-methylaniline10aN-methylation10aspacer10astabilizer10asurface distribution10aTPR10aXPS1 aVijayaraj, Munusamy1 aGopinath, Chinnakonda, S.  uhttps://library.ncl.res.in/content/active-spacer-and-stabilizer-role-zn-cu1-xznxfe2o4-selective-mono-n-methylation-aniline-1