AMORPHOUS ALLOY CATALYSIS .7. ACTIVATION AND SURFACE CHARACTERIZATION OF AN AMORPHOUS CU-TI ALLOY CATALYST PRECURSOR IN THE DEHYDROGENATION OF 2-PROPANOL AND COMPARISON WITH CU-ZR

The activation and catalytic properties of Cu-Ti and Cu-Zr metallic glass precursors in the dehydrogenation of 2-propanol differ substantially. In contrast with Cu-Zr, Cu-Ti can only be activated with Up solution. The pretreatment of Cu-Ti results in catalysts with BET and copper surface areas one order of magnitude smaller than those of Cu-Zr under the same conditions. Cu-Ti exhibits decreasing catalytic activity, while Cu-Zr displays stable activity in the course of the reaction. Crystallization of the metallic glasses prior to HF treatment results in a weaker reactivity toward hydrogen fluoride for both alloys. Scanning electron micrographs of the alloys reveal that HF etching results in surfaces with deep grooves, and copper-rich flakes, a Raney-Cu-like catalyst. Auger electron spectroscopic studies show copper enrichment in the surface region on both alloys after HF treatment. On the surface of Cu-Ti, mostly Cu(II) is detected, whereas Cu(0) and Cu(II) coexist on Cu-Zr. (C) 1995 Academic Press, Inc.