CATALYSTS
Heraeus offers a broad portfolio of palladium complexes with various phosphine ligands
into the corresponding small building blocks , known as monomer and oligomer units , on an industrial scale . In cooperation with the Johannes Kepler University Linz , Heraeus Precious Metals has developed an industrial precious metal catalyst that precisely enables this splitting . The catalyst performance depends on the precious metal precursor solutions used and on the characteristics of the support . Various tests have proven that the special nature of a hydrotalcite ( HTC ) as a support material has a positive effect on the catalyst performance .
Furthermore , an HTC-based platinum catalyst leads to much better lignin conversions in comparison with the HTC support itself . The higher the platinum loading of the catalyst , the higher the preference towards the formation of monomeric and oligomeric structures . The addition of nickel strengthens this effect , with decreased coke formation . ( Figure 1 ).
The best conversion of lignin can be achieved by using a heterogeneous catalyst on HTC as a support material with a metal loading of 5 % platinum and 1 % nickel . This catalyst has already been registered for patent .
Homogeneous catalysts
The importance of effective drugs against novel pathogens has become more than clear worldwide in recent years . Many diseases that are not ( yet ) curable , and additional resistances and new pathogens underline the huge demand for new APIs .
However , assembling effective pharmaceuticals is a difficult task : not only the right molecule but also the right variant must be formed . Homogeneous precious metal catalysts are exactly the precision tools that pharmaceutical researchers use to work out their architecture down to the last detail .
In agrochemicals , the focus of politics and society on environmental protection creates the need for innovation . On the one hand , with constant population growth and against the backdrop of climate change , more and more food must be produced under increasingly difficult conditions . Crop protection products , on the other hand , must become more environmentally friendly . In addition , new trends in dietary and consumption habits arise – a playing field for fine chemistry .
Homogeneous catalysts have long been used in the chemical industry because of their exceptionally high reactivity . To solve current challenges , they are now being used especially in asymmetric hydrogenations or for the direct formation of carbon-carbon bonds , the so-called C-C couplings .
Asymmetric hydrogenation
Asymmetric hydrogenations are gaining importance because they offer a solution to the problem of chirality . Many biologically active molecules are chiral - they exist as an image and a mirror image , called enantiomers . Often only one of two enantiomers is biologically active . Conventional methods usually produce both . They must be separated at great expense and the inactive enantiomer must be disposed of .
Thanks to asymmetric hydrogenation with homogeneous precious metal catalysts , only the active enantiomer is produced . In organometallic iridium , rhodium or ruthenium complexes , the spatial environment of the catalyst is designed by specific ligand selection so that the hydrogen reacts with the target molecule from only one side . Cyclooctadiene complexes are often used in combination with chiral phosphines .
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