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The unique value of the Raney® catalyst is revealed through surface modifications that have extended this familiar platform into novel materials with enhanced productivity in practical hydrogenations. The illustrative examples each yielded new compositions through use of non-nickel metals: as efficient dopants (Pd, Pt), as an inexpensive alloy diluent (Fe) and substrate for plating, or as the primary catalyst metal (Raney® Cu) in a recently identified process upgrading a renewable feedstock. A perspective on the surface chemistry of metals links the various approaches. [ABSTRACT FROM AUTHOR]

Net propylene glycol (1,2 propanediol) yields of up to 94% at 100% glycerol conversion have been achieved over a fixed bed Raney® Cu catalyst in trickle bed mode, at relatively low total pressure, 14 bar (200 psig), and minimal feedstock dilution (20 wt% water). The main identified byproducts are ethylene glycol and ethanol (each <2%), with methanol and 1,3 diol both <1%. The other key operating parameters for high yields are a narrow optimum in temperature (near 205 °C), and a high H2/liquid flow ratio, about 375/0.05 by volume. The effects of chromium promotion have also been studied for effects on side reactions and rates. Our evidence points to initial dehydrogenation as the rate-limiting step in a likely three step mechanism. [ABSTRACT FROM AUTHOR]