Novel non-noble bimetallic Cu-Zn/TiO2 catalysts for selective hydrogenation of butadiene

Supported Cu Nanoparticles as Selective and Stable Catalysts for the Gas Phase Hydrogenation of 1,3-Butadiene in Alkene-Rich Feeds

“…Partial alloying of Zn with Cu and passivation of TiO 2 surface Lewis acid sites by Zn species might play an important role in stabilizing the samples. 35 Further insights regarding the support effect on catalyst stability were recently reported by Masoud et al for Au-based catalysts. 37 SiO 2 -supported Au nanoparticles demonstrated much more stable catalytic performance than TiO 2 -supported ones (10% loss of the initial activity for Au/SiO 2 after 5 days on stream at 200 °C, while Au/TiO 2 loses 90% of its initial activity after 15 h on stream, same conditions).…”

“…A direct comparison between our systems and 5 nm Cu/TiO 2 described by Wang et al tested using the same reaction mixture, yet T = 90 °C, shows that the 5 nm Cu/TiO 2 catalyst lost all more than 90% activity after <10 h on stream. 35 Deactivation was mainly ascribed to significant “green oil” or coke poisoning (formation of C 4+ oligomers or carbonaceous deposit). 6 , 29 , 35 No results for Cu catalysts on SiO 2 have been reported previously; however, differences in stability between SiO 2 - and TiO 2 - supported catalysts were reported by our group for Au-based systems used in selective hydrogenation for the same reaction mixture.…”

“… 35 Deactivation was mainly ascribed to significant “green oil” or coke poisoning (formation of C 4+ oligomers or carbonaceous deposit). 6 , 29 , 35 No results for Cu catalysts on SiO 2 have been reported previously; however, differences in stability between SiO 2 - and TiO 2 - supported catalysts were reported by our group for Au-based systems used in selective hydrogenation for the same reaction mixture. 37 Higher stability was observed for Au nanoparticles immobilized on the silica support than on titania P25 (almost full retention of the activity for Au/SiO 2 catalyst after 16 h at 200 °C, versus 88% loss in activity for Au/TiO 2 tested in the same conditions).…”

“…Unfortunately, the stability of these catalysts was generally poor because of oligomer formation, often termed “green oil formation”, which limited further interest in this type of catalyst. 6 , 29 , 35 …”

“…Not only Pd alloys but also base metals and related alloys such as NiZn, FeZn, and monometallic Ni and Cu were predicted to be good catalysts. 36 Recent experimental developments on Cu-based catalysts were reported by the group of Louis et al 35 In particular, the authors showed that the addition of Zn species to TiO 2 -supported Cu catalysts helped to stabilize the catalytic performance. The monometallic copper lost more than 90% activity within 4 h on stream, while for the Cu 3 Zn 1 sample the decrease in activity was limited to ∼30% during 20 h on stream.…”