Green catalysis by nanoparticulate catalysts developed for flow processing? Case study of glucose hydrogenation

Abstract

Heterogeneous catalysis, flow chemistry, continuous processing, green solvents, catalyst immobilization and recycling are some of the most relevant, emerging key technologies to achieve green synthesis. However, a quantification of potential effects on a case to case level is required to provide a profound answer, whether they can lead to a superior process compared to the industrial standard. To do so, holistic environmental assessment approaches are very useful tools providing insights and decision support during the process development phase. Herein, novel heterogeneous nanoparticulate ruthenium catalysts immobilized on hyperbranched polystyrene (HPS) and nitrogen-doped carbon nanotubes (NCNT) were investigated with respect to their potential environmental impacts and improvements if utilized in an industrially highly relevant process, namely glucose hydrogenation to sorbitol. The results of a comparative Life Cycle Assessment of the alternative catalytic systems under consideration of RANEY® nickel as benchmark catalyst revealed that in particular Ru nanoparticles on porous HPS beads processed under flow-chemistry conditions have the potential to improve the greenness of the overall synthesis, but the concentration of glucose in the reaction mixture is in fact the most influential parameter

Synthesis and Physicochemical Characterization of Shaped Catalysts of β and Y Zeolites for Cyclization of Citronellal

“…In the recent years, an increased attention has been paid to for the synthesis of fine chemicals in continuous mode. − Under such conditions, a compromise should be made between a pressure drop, favorable at large sizes of catalysts, and mass-transfer limitations. Catalyst deactivation as well as product distribution can be different from those obtained under kinetic regime with fine catalyst powders.…”

Production of Sorbitol via Catalytic Transfer Hydrogenation of Glucose

“…Nevertheless, the lower catalytic activity of nickel as compared to other precious-metal-based conventional hydrogenation catalysts, such as ruthenium, results in the need for high hydrogen pressure and harsh operating conditions. Consequently, a significant energy demand must be satisfied compared to that required when using more active hydrogenation catalysts and, thus, higher environmental impacts are associated with the use of Raney nickel catalysts [24].…”

“…Nevertheless, the lower catalytic activity of nickel as compared to other precious-metal-based conventional hydrogenation catalysts, such as ruthenium, results in the need for high hydrogen pressure and harsh operating conditions. Consequently, a significant energy demand must be satisfied compared to that required when using more active hydrogenation catalysts and, thus, higher environmental impacts are associated with the use of Raney nickel catalysts [24].This work focuses on gaining insights into a developing alternative reaction pathway to the conventional hydrogenation procedure used to transform glucose into sorbitol by exploring the feasibility of carrying out the transformation through catalytic transfer hydrogenation (CTH) using a hydrogen donor. CTH is, a priori, a more sustainable alternative to conventional hydrogenation with molecular hydrogen because of the lower requirements for high-pressure conditions.…”

Recent Developments in the Use of Flow Hydrogenation in the Field of Medicinal Chemistry

“…Flow hydrogenation is particularly useful in the reduction in alkene and alkyne bonds as is evident from the examples shown in Table 2. Gericke et al developed ruthenium-nitrogendoped carbon nanotubes (NCNT) and ruthenium-hyperbranched polystyrene-supported (HPS) catalysts, providing a more sustainable process [24]. Gericke et al suggested that HPSand NCNT-supported catalysts are a suitable alternative to Raney Ni and have an increased production rate per mole of catalyst compared to Raney Ni.…”