Effects of irradiation on the catalytic activity of metal oxides

[摘要] This work further develops a technique for changing the electronic and defect structure of magnesium oxide and silica gel catalysts.Relatively small doses of ultraviolet and neutron irradiation have been found to enhance greatly the catalytic activity of MgO for the reaction H 2 + D2 &rlhar2;2HD. The enhancement by radiation depends on the extent of degassing of the catalyst prior to irradiation; the less active samples are more sensitive to irradiation. For samples activated at 291°C, ultraviolet irradiated MgO reaches a precise saturation value of catalytic activity, while neutron irradiated samples continue to increase in activity upon further irradiation. Both types of irradiation produce a large initial increase in activity. Changes in activation energy depend on the thermal activation and type of irradiation. The activation energy either increases or remains unchanged for neutron irradiation, while ultraviolet irradiation does not cause a change. For this system, a simple model based upon Fe+3 as the irradiation induced site has been developed.

[发布机构] Rice University

[效力级别] engineering