Novel Mesoporous Solid Acid Catalyst UDCaT-4
COMMUNICATIONS
These results clearly show the stability of the UDCaT-4 calcined at 6508 for 3 to afford the catalyst called UDCaT-4;
anal.: Zr 9.01, Al 0.16%, S 1.1±%w/w.
in the presence of corrosive acids like HCl. The stability
of zirconia-based catalyst is questionable when water is
generated as a co-product. When fresh sulfated zirconia
is mixed with water, the pH of the suspension decreases
quickly as a result of sulfate group hydrolysis which is
confirmed by the identification of sulfate ions in the
Reaction Procedure and Analysis
Liquid-phase reactions were conducted in a glass reactor of
5
cm. i.d. and 10 cm height with four glass baffles and a four-
aqueous phase. A test for sulfate leaching was con- bladed disc turbine impeller located at a height of 0.5 cm from
ducted for fresh and reused catalyst by pH measure- the bottom of the vessel and mechanically agitated with an
ment[ and it was found that there was no leaching of electric motor. In a typical alkylation reaction, 0.5 mol toluene
2±7
was reacted with 0.05 mol benzyl chloride with a catalyst
sulfate ions from UDCaT-4. UDCaT-4 was found to
3
loading of 0.018 g/cm , 1000 rpm and 908C. The reaction
mixture was allowed to reach the desired temperature, the
retain its activity for isopropylation of mesitylene at
2
508C for more than 50 h with a zero drop in conversion
initial/zero time sample collected and catalyst added there-
after. Samples were withdrawn periodically and analyzed on a
Chemito GC equipped with a stainless steel column (dia. 1/8 in
and length 4 m) packed with a liquid stationary phase of 10%
OV-1± on Chromosorb WHP, and an FID detector.
Vapour-phase alkylation was conducted in a down-flow
fixed-bed haste alloy HC-2±6 reactor with 25.4 mm ID and
and selectivity. This study further supports that there is
no leaching of the sulfate ion from UDCaT-4 and that it
is a stable catalyst. These activity studies further bolster
the assumption drawn from the spectroscopic studies
regarding the generation of more acidic centers in
UDCaT-4 than in PAZ.
In conclusion, a novel mesoporous solid acid catalyst 300 mm length at atmospheric pressure, equipped with an
upstream vaporizer and a downstream condenser. The liquid
UDCaT-4 was synthesized with superior activity and
feed containing a 1:1 molar ratio of mesitylene and isopropyl
stability and high surface area and ordered mesoporos-
alcohol was fed by a double piston (Well Chrom HPLC-pump
ity. This catalyst exhibits superior activity than bulk PAZ
K-120) pump to the vaporizer using N as a carrier gas at a
2
in the liquid-phase alkylation of toluene with benzyl
chloride and vapour-phase alkylation of mesitylene with
isopropanol. It is being tested in several other organic
syntheses.
À1
WHSVof 20 h at 2508C and the effluent was analyzed by GC
GC1000 Chemito) equipped with stainless steel column of
(
3
.8 mm  4 m packed with 10% SE-30 on chromosorb WHP
and a FID detector.
In a typical run, 1 g catalyst was charged to the reactor and
stacked in between glass beads and ceramic wool. The reactor
was maintained under isothermal conditions during all runs.
Experimental Section
Acknowledgements
Catalyst Preparation
HMS: The hexagonal mesoporous silica (HMS) was prepared
using the following procedure. Dodecylamine (5 g) was
dissolved in ethanol (41.8 g) and distilled water (29.6 g).
Tetraethyl orthosilicate (20.8 g) was added under vigorous
stirring. The addition of ethanol improved the solubility of the
template. The reaction mixture was aged for 18 h at 308C. The
clear liquid above the white colored precipitate was decanted
and the precipitated HMS was dried on a glass plate. The
template was removed by calcining the resulting material at
GDY acknowledges Darbari Seth Professorship Endowment
for financial assistance and CSIR under NMITLI programme
(
2001 ± 03).
References
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asc.wiley-vch.de
¹ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
393