1070-4272/03/7610-1615 $25.00 C 2003 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 76, No. 10, 2003, pp. 1615!1619. Translated from Zhurnal Prikladnoi Khimii, Vol. 76, No. 10, 2003,
Original Russian Text Copyright + 2003 by Vlasenko, Kochkin.
Direct Single-Stage Conversion of Synthesis Gas
Influence of the Sequence of Metal Introduction
into Cu, Pd-Zeolite Catalysts on the Degree of Cu
and Pd Reduction and Catalyst Acidity
N. V. Vlasenko and Yu. N. Kochkin
Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, Kiev, Ukraine
Received March 25, 2003
Abstract-The influence of the sequence of Cu and Pd introduction into zeolite matrice when preparing Cu,
Pd-zeolite catalysts on their acidity and degree of metal reduction was studied. The mutual influence of Cu
and Pd on their reducibility was analyzed. The selectivity of Cu, Pd-zeolite catalysts in conversion of syn-
thesis gas to different products was elucidated.
Dimethoxymethane (DMM) is a promising additive
to diesel oil . It is known  that this compound
can be prepared in high yield by condensation of
methanol with formaldehyde at 150-180oC and a pres-
sure of 1 MPa. Another promising route to this prod-
uct is the single-stage conversion of synthesis gas.
Thermodynamic calculations showed that this route
is feasible under fairly mild conditions (1803220oC,
pressure above 0.5 MPa). In this process, Pd, Cu-con-
taining zeolites can be used as catalysts. Under these
conditions, DMM can be prepared in a single stage
combining three reactions: hydrogenation of synthesis
gas to methanol, dehydrogenation of methanol to
formaldehyde, and DMM formation by condensation
of methanol with formaldehyde.
It is known [4, 5] that, in preparing supported cat-
alysts, the most uniform distribution of metals on
the support surface is achieved with ion-exchange sup-
ports by ion-exchange sorption of metals, e.g., from
aqueous solution of their ammine complexes [4, 5].
To obtain catalytically active surface, a metal-contain-
ing precursor is calcined and then reduced with hy-
drogen [6, 7]. In this treatment, the support surface is
dehydroxylated and deammonated, and the reduced
metals can be oxidized by reaction with the support.
A catalyst prepared by this technique is a polyfunc-
tional system containing catalytically active metallic
and free acid sites. Owing to the mutual influence
of these sites, the metal atoms can modify the acid
sites and, in turn, the acid sites can affect the valence
state of the metal . For reduced catalysts containing
several metals, their chemical composition is control-
led not only by interaction of the metals with the sup-
port surface, but also by interactions between different
metals. Thus, the features of physicochemical pro-
cesses occurring during catalyst preparation are re-
sponsible for the state of the catalyst surface, and, ulti-
mately, for the activity of the catalytic sites. The mu-
tual influence of copper and palladium has been main-
ly studied for catalysts prepared by simultaneous ap-
plication of these metals on a support surface [8, 9].
In these studies, due attention was not given to the in-
fluence of the sequence of the metal application. How-
ever, it is known that this factor can affect substantial-
ly the catalyst properties .
In this study, we analyzed how the sequence of in-
troduction of Cu and Pd in a zeolite catalyst designed
for single-stage conversion of synthesis gas to di-
methoxymethane affects both the catalyst acidity and
the degree of reduction of the metals.
When preparing Cu, Pd-zeolite catalysts, we used
Ps(60) and Ps(200) Pentasil zeolites as supports.
The Ps(60) and Ps(200) zeolites have the SiO
ratio of 60 an 200 and the cation-exchange capacity
(CEC) of 0.20 and 0.57 mg-equiv g