Carin Seechurn of Sinocompound looks at alternatives to precious metals in chemocatalysis
The rise of non-PGM catalysis
Carin Seechurn of Sinocompound looks at alternatives to precious metals in chemocatalysis
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Figure 1 - Industry-relevant processes where non-PGM catalysis provided advantage over PGM-catalysis |
Platinum-group metal ( PGM ) catalysis has been the standard in pharmaceutical synthesis for decades . The utility of PGM-catalysed reactions has been recognised with Nobel Prizes and countless commercial processes . The advantages are clear : PGM catalysts have high functional group tolerance , easily tuned phosphine ligands and well-researched reactions .
However , chemists and companies are increasingly aware of the drawbacks of PGM catalysts . PGMs are costly , and are found in much lower abundance than non-PGM metals . These factors , as well as growing global supply-chain issues , lead to supply insecurity .
Sustainability and toxicity are also cited as a reason to adopt non-PGM catalysts in manufacturing . Less toxic catalysts could conceivably allow more residual metal in the final API ,
although reviews of the toxicology data for various catalytic metals have not resulted in definitive conclusions as to which group is less toxic .
A sustainability-focused comparison of PGM and non-PGM catalysis is also difficult due to the large number of variables involved in these reactions ; however , studies have shown that the production of non-PGMs generates much less CO 2 than that of PGMs .
Non-PGM catalysts have been used industrially for a wide range of applications , including the production of syngas ( nickel ), the Fischer-Tropsch process for synthetic fuels ( cobalt and iron ), the water-gas shift reaction for hydrogen ( iron and copper ), the DuPont adiponitrile process for polyamide precursors ( nickel ), the production of sulfuric acid ( vanadium ), and electrochemistry ( nickel ).
The Haber-Bosch process produces ammonia using an iron catalyst , which is then used as a starting material for 450 million tonnes / year of nitrate fertiliser . DuPont ’ s nickel-catalysed adiponitrile process produces hundreds of thousands of tonnes / year . Polyethylene and other polymers are synthesised in the millions of tonnes using reactions catalysed by nickel and titanium .
Non-PGM catalysts are emerging as viable alternatives for pharmaceutical processes . These non-precious metals are much more abundant , less expensive and more sustainable , and have more easily managed waste streams . Cross-couplings , hydrogenations , oxidations , aminations , alkoxylations , hydrosilylations , C-H activations and other reactions have all been developed with non-PGM catalysts .
In support of this ongoing development , Sinocompound works
24 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981