論文

The authors developed eco-friendly non-chromium catalysts for acetaldehyde production through bioethanol dehydrogenation, consisting of copper and calcium silicate. Acetaldehyde selectivity was higher over copper calcium silicate catalysts with a CuO content of 40 wt % or more, because the number of acid sites on the calcium silicate was reduced, which helped prevent formation of byproducts. It was found that high ethanol conversion (39%-57%) and high acetaldehyde selectivity (91%-95%) could be achieved simultaneously at high temperature and high weight hourly space velocity conditions. Furthermore, it was shown that stable acetaldehyde production could be maintained over 20 h of time-on-stream. These catalysts were prepared from commercially available precursors and could be used in place of conventional copper chromite catalysts.

The reaction of methanol with silicon was carried out in a fixed-bed reactor at 463-533 K. In order to determine the kinetics of the reaction per reaction site on the silicon surface, a pressure- (or temperature-) transition method was employed. The reaction order with respect to methanol was 1.0 and 1.4 for the Si-CuC1 mixture preheated at 513 and 723 K, respectively, indicating that the rate-determining step is not the diffusion of silicon or copper species to the reaction site, but the chemical process involving methanol. Kinetics also indicate that the nature of the reaction sites changes with the preheating conditions of the mixture.

Hydrosilylation of acetylene with trichlorosilane or trimethoxysilane was carried out using a vapor-phase flow reactor with use of tetraammineplatinum(II) chloride in polyethylene glycol medium supported on silica gel as a catalyst, which is an active and thermally stable supported liquid-phase catalyst prepared readily from easily available materials, tetraammineplatinum(II) chloride, polyethylene glycol and silica gel.

The mesopore walls of ordered mesoporous silicas were coated with zirconia layers at room temperature using zirconia tetra-n-butoxide dissolved in dry toluene. It was found that coating the silicas three times with zirconia layers was sufficient to completely cover their pore walls with zirconia. The coated mesoporous silicas demonstrated high resistance to a 2 M sodium hydroxide solution at 0 °C. Prior to being coated three times with the zirconia layers, the silica walls were partially coated with 3-(2-aminoethylamino)propyltrimethoxysilane so that diamino groups could be grafted onto the pore walls; this was done so that they could be used as base-resistant adsorbents for copper(ii) ions that had been dissolved in basic solutions. The grafted diamino groups, which captured copper(ii) ions, were protected from the basic solution, as the silyl in the diamino groups was covered with zirconia layers.