Activity in hydrogenolysis

Earlier transition metals, as zirconium and hafnium, are still more active in hydrogenolysis, which allows zirconium hydrides to be used in depolymerization reactions (hydrogenolysis of polyethylene and polypropylene) [89], In this case, the zirconium hydride was supported on silica-alumina. Aluminum hydrides close to [(=SiO)3ZrH] sites would increase their electrophilicity and, thus, their catalytic activity. A catalyst prepared in this way was able to convert low-density polyethylene (MW 125000) into saturated oligomers (after 5h) or lower alkanes at 150°C (100% conversion). It was also able to cleave commercial isotactic polypropylene (MW 250000) under hydrogen at about 190 °C (40% of the starting polypropylene was converted into lower alkanes after 15 h of reaction). 

A neutral and non pyrophoric Pd catalyst active in hydrogenolysis of benzyl-N or O-benzyl bonds using Pd(OH)2 on carbon. 

The platinum-ruthenium combination has been of interest in fuel-cell technology, because ruthenium imparts some resistance to poisoning by carbon monoxide as with platinum-iridium, it is important to see whether joining metals of very different activities in hydrogenolysis creates binary centres having new properties. The few available studies ° ° all confirmed ruthenium s superior activity for hydrogenolysis (except for cyclopentane ) and its inability to do much else under normal circumstances. It does however induce other reactions characteristic of platinum at a temperature (493 K) well below that at which that metal would be active by itself. With Pt/AlaOs,X-ray absorption spectroscopy showed... 

The authors have previously [4] shown how the size of I Auioo., sols increased with decreasing x in line with expectation and that such sols were catalytically active in hydrogenolysis of alkanes. 

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