Y. Maki et al., STRUCTURES OF H3PO4 SIO2 CATALYSTS AND CATALYTIC PERFORMANCE IN THE HYDRATION OF ETHENE/, Applied catalysis. A, General, 170(2), 1998, pp. 269-275
The hydration of ethene was carried out over H3PO4/SiO2 having various
amounts of H3PO4. The rate of the ethanol formation increased markedl
y with the increasing H3PO4 loadings, in particular above 60-70 wt%. B
y X-ray diffraction (XRD), and P-31 and Si-29 MAS NMR methods, it was
revealed that various silicon phosphates were produced in the preparat
ion of the catalysts. The structures of the phosphates depended on the
H3PO4 loadings. It was suggested that Si(HPO4)(2) . H2O species which
formed at higher H3PO4 loadings were hydrolyzed to H3PO4 and SiO2 dur
ing the course of the reaction, yielding the catalysts with high perfo
rmance. The bulk phase of the H3PO4 was involved in the reaction. (C)
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